ALBERT

Notes: Various mechanisms which have been proposed for the reaction between ferrous iron and hydrogen peroxide are reviewed. Two of these mechanisms appear equally satisfactory on the basis of present evidence: that of Bray and Gorin, involving formation of tetravalent (ferryl) iron, and that of Haber and Weiss, involving formation ofhydroxyl and perhydroxyl radicals. Mechanisms involving these intermediates have been developed for the ferric iron-catalyzed decomposition of hydrogen peroxide; the mechanism of Bray and Gorin appears satisfactory, while that of Haber and Weiss leads to certain inconsistencies. A mechanism with ferrous iron and hydroxyl and perhydroxyl radicals as intermediates is presented, which accounts for the experimental observations in the ferric iron-catalyzed decomposition of hydrogen peroxide. The reaction between hydrogen peroxide and ferrous iron induces the reaction between hydrogen peroxide and various organic compounds; this induced reaction (termed a Fenton reaction) is a chain reaction which is initiated by the active intermediates (ferryl iron or hydroxyl radical) formed in the primary reaction. The determination of hydrogen peroxide by reaction with ferrous iron, if carried out in the presence of various organic compounds (termed promoters), gives incorrect results, due to induced oxidation of the promoters; other compounds, termed suppressors, reduce the extent of this induced oxidation of promoters. It appears that both types of compounds react with ferryl iron or hydroxyl radical to form radicals, which if formed from promoters, reduce ferric iron or hydrogen peroxide, while the radicals formed from suppressors oxidize ferrous iron. These considerations are of particular importance in the determination of organic hydroperoxides. The reaction between hydrogen peroxide or organic peroxides and ferrous iron can induce, or initiate, the polymerization of vinyl monomers; this is an example of redox polymerization, which is of considerable practical importance at present.

Notes: Cellobiose wird als Glykolsäure-glykosid nach der Azid-methode mit Protein kondensiert. Ferner werden aus Lacto-bionsäure und Proteinen nach der Azid-methode Lacto-bionyl-proteine synthetisiert.

Notes: 2-Chlorbutadien-1,3 (Chloropren) bildet schon bei niedrigen Temperaturen mit molekularem Sauerstoff ein Peroxyd. Die Bildungsgeschwindigkeit dieses Peroxyds ist so groß, daß es schwierig ist, peroxydfreies Chloropren herzustellen. Dies gelingt durch sorgfältige Destillation unter reinstem Stickstoff.Die Versuche zur Isolierung des Chloroprenperoxyds ergaben wegen seiner leichten Zersetzlichkeit keine befriedigenden Ergebnisse. Die quantitative Bestimmung des Peroxyds in Chloropren gelingt nach den üblichen Methoden nicht oder nur sehr schwierig. Chloroprenperoxyd oxydiert Antioxydantien, wie z. B. Phenyl-β-naphthylamin, zu gefärbten Produkten. Da Phenyl-β-naphthylamin die weitere Autoxydation des Chloroprens unterbindet, kann auf dieser Grundlage eine photometrische Bestimmung des Peroxyds durchgeführt werden.Die Geschwindigkeit der Sauerstoffaufnahme von Chloropren bei 0°C wurde volumetrisch gemessen. Die Sauerstoffaufnahme ist ein autokatalytischer, gleichförmig beschleunigter Vorgang. Er wird von Tetralinperoxyd stark beschleunigt, nicht aber von Benzoylperoxyde. Es wurden andere katalytisch wirkende Stoffe und der Einfluß des Lichtes untersucht.Da Chloroprenperoxyd die Polymerisation des Chloroprens auslöst und stark beschleunigt, ist es zweckmäßig, für die Stabilisierung dieser ungesättigten Verbindung solche Stoffe anzuwenden, die nicht nur die Polymerisation, sondern auch die Autoxydation hemmen. Die stabilisierende Wirkung der Antioxydantien wird bei Anwesenheit von Chloroprenperoxyd und Chlorwasserstoff nach einer Induktionsperiode durchbrochen. Dies kann dadurch erklärt werden, daß Phenyl-β-naphthylamin im Falle des Chloroprenperoxyds durch Oxydation, im Falle des Chlorwasserstoffs als Salz unwirksam gemacht wird.

Notes: Es wird ein einfaches Verfahren angegeben, den Transport von Wasser durch Textilfaserschichten zu messen, die einerseits in Wasser tauchen und andererseits an Luft mittlerer relativer Feuchtigkeit grenzen. Proteinfasern transportieren das Wasser langsam, Baumwolle rascher und Viskosekunstfasern sehr rasch.

Notes: Es wird der Einfluß von Seitenketten auf die Höhe der Viskositätszahl Zη von niedermolekularen Estern untersucht. Bei Dicetylmalonestern und Dicetylessigestern hat die Länge der Estergruppe keinen Einfluß auf die Höhe der Viskositätszahl. Bei substituierten Malonsäuredicetylestern resp. Disterylestern ändert sich dagegen die Viskositätszahl mit der Länge der in die CH2-Gruppe substituierten Alkylreste, und zwar ist sie bei kurzkettigen Substituenten kleiner, bei langgliedrigen größer als bei den unsubstituierten Verbindungen gleicher Kettenlänge. Das gleiche Verhalten zeigen β-alkylsubstituierte Stearinsäureester. Es wird weiter versucht, inwieweit das Einsteinsche Viskositätsgesetz in veränderter Fassung zur Klärung dieses Viskositätsverhaltens herangezogen werden kann.

Notes: Da nach den üblichen technischen Verfahren die Isolierung von Pektinen unvermeidlich mit einem gewissen Abbau verbunden ist, wurden die schonendsten Bedingungen festgestellt, unter denen es noch möglich ist, Pektin aus dem Fruchtfleisch von Äpfeln in ausreichender Menge zu gewinnen. Durch Wahl des günstigsten Reifezustandes, Ausschaltung einer Enzymtätigkeit, Einhaltung möglichst neidriger Extraktionstemperaturen und eines geeigneten pH konnte ein wenig abgebautes Pektin crhalten werden, dessen Methoxylgehalt dem für eine vollständig veresterte Polygalakturonsäure berechneten sehr nahe kommt. Die Molekulargröße wurde viskosimetrisch an einem aus diesem Material gewonnenen Pektinnitrat bestimmt, das nach einer schonenderen Nitrierungsmethode als der bisher üblichen hergestellt war. Die erhaltenen Werte liegen über den bisher beobachteten. Das im Apfelsaft vorhandene „freie Pektin“ wurde als niedriger molekular befunden.

Notes: Aus einer Zusammenstellung von Viskositätsmessungen an niedermolekularen Kettenmolekülen mit Doppelbindungen geht hervor, daß die trans-Formen eine höhere und die cis-Formen eine niedrigere Viskosität haben als die analogen gesättigten Verbindungen. Die verschiedene Viskosität von trans-, cis- und gesättigten Verbindungen kann mit der verschiedenen Form und Elastizität der Kettenmoleküle erklärt werden. Maleinsäureester und Maleinsäurepolyester lassen sich mit Brom als Katalysator in die entsprechenden Fumarester umlagern.

Notes: Es wurde die Polymerisationsgeschwindigkeit des Vinylchlorids bei 50° unter Zusatz verschiedener Mengen Benzoylperoxyd als Katalysator untersucht, indem der Umsatz das Molekulargewicht und die Zeitdauer beginnender Trübung durch Ausfallen des Polymerisats bestimmt wurde.Der Umsatz steigt zunächst langsam, dann schneller mit der Zeit an; über 80 - 90% nimmt er nur noch sehr langsam zu, so daß die letzten 1 - 2% praktisch nicht mehr polymerisieren. Mit sinkender Katalysatorkonzentration wird die Reaktion langsamer, derart, daß sich die Umsatzzeitkurven durch Dehnung der Zeitachse proportional der Wurzel aus der ursprünglichen Katalysatorkonzentration zur Deckung bringen lassen. Bis zu 70 - 80% läßt sich der Umsatz durch die Gl. u = (eat  -  1)b gut darstellen, wobei b = 0,1 und a = 0,240 · √c20 zu setzen ist.  -  Gegen Ende der Reaktion ließ sich im restlichen Monomeren Salzsäure nachweisen.Das Molekulargewicht nimmt mit steigender Menge Benzoylperoxyd und Sauerstoff deutlich ab; bei mäßigen Peroxydkonzentrationen wird dieser Effekt in der Streuung der Versuchswerte nicht sichtbar.  -  Die Zeit bis zur beginnenden Trübung ändert sich umgekehrt proportional der Wurzel aus der Katalysatorkonzentration und ist ferner unter reinem Sauerstoff größer, unter Stickstoff kleiner als unter Luft.Der Katalysator verschwindet während der Polymerisation, und zwar in um so stärkerem Maße, je höher seine ursprüngliche Konzentration, und um so weniger, je größer die Menge an Sauerstoff ist.  -  Mit Kaliumpersulfat erfolgt die Polymerisation nur in der wäßrigen Phase.Mit den Beobachtungen im Einklang steht das folgende Reaktionsschema (B = Benzoylperoxyd, M = monomeres Vinylchlorid). Die Hemmung der Polymerisation durch eine Anzahl von dritten Stoffen wurde orientierend, etwas eingehender die durch Styrol untersucht. Schwache Reduktionsmittel, Vinylderivate und einige anorganische Stoffe hemmen die Polymerisation, während chemisch indifferente Stoff sie nicht beeinflussen. Die Hemmung beruht vermutlich auf vorzeitigem Kettenabbruch.

Notes: Der bei Pektinpräparaten festzustellende P2O5-Gehalt in der Asche stammt teils von anorganischen und organischen Begleitstoffen (Phosphatiden), teils aber auch von Veresterungen der Pektinketten durch H3PO4; im Protopektin der Pflanzen hat man Vernetzungen der Pektinketten durch H3PO4-Brücken zu „Übermolekülen“ anzunehmen, die zahlenmäßig jedoch gegenüber den Vernetzungen durch mehrwertige Metallionen über die Karboxylgruppen zurücktreten.

Notes: 1Die Untersuchungen von Ohara (1933) über das polarisationsoptische Verhalten des Seidenfibroins wurden einer kritischen Betrachtung unterzogen und dabei Abweichungen von der Wienerschen Theorie festgestellt.2Die Hauptbrechungsindizes von Fibroinfäden, die 40 Stunden bei 100°C über P2O5 getrocknet worden waren, wurden nach der Immersionsmethode von Becke gemessen und zu für eine Wellenlänge von 589 mμ gefunden. Daraus resultiert eine Doppelbrechung von 0,0506 und für den Schwerpunkt des weißen Lichtes bei 550 mμ eine solche von 0,0514.3Imbibitionsversuche an trockenem und feuchtem Fibroin ergeben eindeutig das Fehlen eines Stäbchendoppelbrechungseffektes. Dies steht im Gegensatz zu den Untersuchungen von Ohara. Der mit Hilfe der Imbibitionsmethode gefundene Wert der Doppelbrechung stimmt mit dem der Immersionsmethode gut überein.4Die Abweichungen von diesem Wert in Wasser und wäßrigen Gemischen als Imbibitionsmedien lassen sich weitgehend mit Hilfe der Quellung erklären.5Durch Quellung und nachfolgende Imbibition kann keine Verstärkung eines etwa nur schwach entwickelten Stäbchendoppelbrechungseffektes erreicht werden.6Elektronenoptische Aufnahmen vermitteln Einblick in den Feinbau des Fibroins, welches aus feinen Fibrillen mit ganz verschiedenen Durchmessern besteht, die sehr fest und dicht gepackt sind.

Notes: Die molekulare Ultraschallgeschwindigkeit ist eine additive Eigenschaft für substanzen mit niedrigem Molekulargewicht und ergibt sich mit großer Annäherung aus der Summe der Geschwindigkeiten der verschiedenen Radikale, die das Molekül bilden.Die Übereinstimmung zwischen der experimentell festgestellten Geschwindigkeit und der auf Grund der Geschwindigkeiten der Radikale berechneten scheint besser zu sein als die auf Grund der Bindungsgeschwindigkeiten nach Lagemann und Corry berechneten. Wie schon von diesen Forschern angegeben, liefern die Bindungsgeschwindigkeiten zufriedenstellende Ergebnisse nur für unverzweigte Verbindungen.In den Verbindungen mit niedrigen Molekulargewichten führt die Gegenwart von Verzweigungen in den Molekülen zu einer Erniedrigung der molekularen Ultraschallgeschwindigkeit, die jedoch sehr geringfügig ist (12 Einheiten für die Methyl- und 20 für die Äthylgruppe in anderen Stellungen als  - 1 und  - 2).Für Verbindungen mit hohem Molekulargewicht und unverzweigter Kette stimmt der Wert der grundmolekularen Ultraschallgeschwindigkeit, d. h. bezogen auf die Grundgruppe, mit den auf Grund der Bindungsgeschwindigkeiten und auch mit den auf Grund der Radikalgeschwindigkeiten berechneten überein. Für verzweigte Moleküle ist die Übereinstimmung für die Radikalgeschwindigkeit besser, wobei die Erniedrigung der grundmolekularen Geschwindigkeit infolge der Verzweigungen höher ist im Falle von Verbindungen mit hohem als mit niedrigem Molekulargewicht.Die Bestimmung des Verhältnisses zwischen der experimentellen und berechneten Geschwindigkeit kann ein Mittel darstellen, um Anzahl und Größe der Verzweigungen zu bestimmen. Diesem Verhältnis ist die Bezeichnung „Formfaktor“ gegeben worden.Der Formfaktor ist gleich 1 oder etwas höher für die unverzweigten oder wenig verzweigten Verbindungen mit hohem Molekulargewicht (Paraffine, Polyäthylene, Polyäthylenoxyd, Nylon), niedriger als 1 für die verzweigten Verbindungen: 0,90 im Naturgummi, der eine Methylverzweigung an jedem vierten Kohlenstoffatom in den langen Ketten trägt, und 0,79-0,80 in den Polyisobutylenen mit zwei Methylverzweigungen an jedem zweiten Kohlenstoffatom in der Kette.Niedrigere Werte als der Naturgummi und unwesentlich höhere als die Polyisobutylene weisen die Formfaktoren des Polyalfabutylens und des Polystyrols auf (0,82), die eine äthylische, bzw, eine phenylische Gruppe auf jedes zweite Kohlenstoffatom in der langen Kette besitzen; dies beweist auch einen Einfluß der Länge der Verzweigungen auf den Formfaktor in dem Sinne, daß letzterer um so mehr erniedrigt wird, je größer die Verzweigung ist.Der Einfluß der Häufigkeit der Verzweigungen und ihrer Länge auf den Formfaktor wird beim Polymethylmetakrylat bestätigt, da diese Verbindung den niedrigsten von uns festgestellten Formfaktor aufweist; diese Verbindung besitzt nämlich zwei Verzweigungen an jedem zweiten Kohlenstoffatom der Kette, und zwar eine Methylgruppe und eine methylierte Karboxylgruppe.Die Übereinstimmung der Formfaktoren des Buna und des hydrierten Buna mit dem des Polyalfabutylens ist ein weiterer Beweis, daß die nicht bei niedriger Temperatur ausgeführte Polymerisierung des Butadiens in den Stellungen 1 - 2 oder 2 - 3 und nicht in der Stellung 1 - 4 stattfindet. Dies steht im Einklang mit den kürzlich mitgeteilten Versuchsergebnissen von Hanson und Halverson bei gestrecktem Buna.Der niedrige Formfaktor des Polyvinylisobutyläthers (0,79) kann ein Zeichen für den Einfluß der sekundären Verzweigungen auf den Formfaktor sein.Schließlich bestätigt die Unveränderlichkeit des Formfaktors für alle untersuchten Polyisobutylene mit verschiedenen Molekulargewichten, daß für hochmolekulare Verbindungen die grundmolekulare Ultraschallgeschwindigkeit und demzufolge der Formfaktor vom Molekulargewicht unabhängig ist.

Notes: Durch Untersuchung der Kettenlängenverteilung von oxydative in Kupferoxydammoniaklösung abgebauten Buchen- und Fichtencellulosen wird gezeigt, daß ebenso wie bei Baumwoll- und Ramiecellulosen eine Vereinheitlichung bei Polymerisationsgraden zwischen 400 und 500 eintritt. Auch bei hydrolytisch abgebauten Produkten ist dieser Effekt zu bemerken, läßt sich jedoch wegen der Viskositätsanomalien nicht quantitativ auswerten. Aus den Befunden wird geschlossen, daß auch in Holzcellulosen im Abstand von ca. 500 Glucoseresten Lockerstellen vorhanden sind, die durch Oxydationsmittel und Säuren erheblich schneller gespalten werden als die β-glucosidischen Bindungen. Diese periodische Struktur ist für alle bisher untersuchten Cellulosearten im Abstand der Lockerstellen identisch, jedoch unterschieden durch das Verhältnis der Spaltungsgeschwindigkeiten. Aus elektronenmikroskopischen Aufnahmen wird geschlossen, daß die Lockerstellen in Ebenen senkrecht zur Faserrichtung angeordnet sind.

Notes: The relationships which exist between the solvation and shape of colloid particles, as well as between solvation and viscosity, are discussed. From the most important experiments on these subjects the following conclusions may be drawn. Solvation is dependent on the size and shape of the particles and on the chemical relationship of the dispersion medium to the dispersed portion. True or chemical solvation is generally very small and there is no reason to speak of a thick and tightly bound solvent layer. The solvation of compactly formed particles of spherocolloids is greater, the smaller the particles (all other conditions being equal). Solvation is greater, the more loosely the particles are formed (for dispersion mediums having similar chemical properties and for similar dispersed or dissolved substances). Solvation increases when a corpuscular particle is transformed into a rodlike or threadlike particle; the viscosity also increases; if the threads are further broken down into smaller fragments, then the viscosity decreases, but a further increase in the chemical solvationis supposed to occur. The stability of many lyophilic sols, especially the proteins, depends very little on the solvation; it is mainly dependent on the chemical characteristics of the atomic groups which are found on the surfaces of the particles; the least stability is found for surfaces which contain heteropolar groups - that is, surfaces which have the same number of positive and negative ions.

Notes: The conductance in diphenyl ether at 35°C. and 60 cycles of the picrate of a 4-vinylpyridine-styrene copolymer (10:90) has been measured. The equivalent conductance, based on the nitrogen content, is of the same order as that of picoline picrate, and varies with concentration in accordance with the law of ion association.

Notes: A polyvinyl acetate polymer of medium viscosity was fractionated into sixteen fractions (first series) and three of the larger of these further separated into twenty subfractions (second series). The intrinsic viscosities and the osmotic pressure molecular weights were determined at 25°C. and the relation between them was found to be expressed by the equations: first series: [η] = (1.88 × 10-4) M0.69; second series: [η] = (1.76 × 10-4) M0.68. The data indicate that little, if any, increase in homogeneity is to be expected by further successive fractionations and that the equations applicable to the second fractionation series are representative of essentially homogeneous polyvinyl acetates in acetone. An equation applicable to fractionated and unfractionated vinyl acetate polymers is described that is useful in obtaining the intrinsic viscosity from a single viscosity measurement. Several unfractionated materials from different sources were also studied and the calculated ratios of the viscosity-average to the number-average molecular weight indicate that the degree of heterogeneity of chain-length distribution increases with increasing average molecular weight.

Notes: The rate of emulsion copolymerization of butadiene and styrene, with soap as emulsifier and potassium persulfate as catalyst, is extremely small at 50°C. The presence of very small amounts of high-molecular mercaptans promotes the copolymerization reaction. The promoting effect is at a maximum for primary, secondary, and tertiary dodecyl mercaptans and decreases for mercaptans of either higher or lower molecular weight. The promoting effect is independent within wide limits of the amount of mercaptan added after the minimum quantity has been exceeded. Mercaptans which are poor promoters may be so because they fail to bring about chain initiation or because they aid in chain termination. The low-molecular mercaptans which are poor promoters prevent the high-molecular mercaptans from exerting their good promoting effect when a mixture of both types of mercaptans is used. The mechanism of the promoting effect of mercaptans upon the emulsion copolymerization of butadiene (75 parts) and styrene (25 parts) or upon the polymerization of butadiene alone is not yet clear.

Notes: An empirical equation is described which predicts the intrinsic viscosities of 75:25 butadiene-styrene emulsion copolymers from data on mercaptan consumption. The form of the equation is as follows: \documentclass{article}\pagestyle{empty}\begin{document}$$\left[ \eta \right] = \left[ {\frac{{aP}}{{R_0 R}} + \frac{b}{{R_0 }}\int_0^P {\frac{{dP}}{{dR}}dP} } \right]^c $$\end{document} where [η] is the intrinsic viscosity, P is the conversion, R is the fraction of mercaptan consumed, R0 is the mercaptan charged, and a, b, and c are constants equal to 0.22, 1.12, and 0.66, respectively. Evidence is given that the intrinsic viscosity of mutual-recipe polymers can be described satisfactorily in terms of mercaptan consumption.

Notes: The calculation of the “theoretical” minimum modifier requirement, TMMR, for butadiene-styrene (75:25) copolymers of given intrinsic viscosities at various conversions is described. The TMMR of 75% conversion polymer of intrinsic viscosity 2.0 is R0 = 0.28, which is only about 60% of the value of R0 for commercial primary dodecyl mercaptan (C.M.) in large-size reactors. The efficiency, E, of a modifier for 75:25 butadiene-styrene copolymerization using soap as emulsifier and persulfate as catalyst has been defined by and calculated from the equation: \documentclass{article}\pagestyle{empty}\begin{document}$$E = \frac{{P\left( {0.2 + P} \right)}}{{R_0 \left( {M_v \times 10^{ - 5} } \right)}}$$\end{document} where Mv is the intrinsic viscosity molecular weight of the polymer at conversion, P, with an amount of mercaptan, R0, charged with the monomers. For all modifiers the efficiency is low at low conversions and gradually increases to a maximum with increasing conversion. For different modifiers this maximum may be as at low as 10% conversion or at higher than 80% conversion. After the maximum the efficiency decreases with further increase of conversion. The most efficient modifier for the production of polymers of intrinsic viscosity, [η], at conversion, P, will meet the following conditions, R = 1 at conversion, P, and dP/dR is constant. Inefficient modifiers may be made more efficient by changing the conditions or procedure of polymerization in such a way that the modifier more nearly complies with the above conditions.

Notes: The swelling of vulcanized natural rubber, Buna S, neoprene, Perbunan, and Perbunan Extra was measured in various organic liquids. The essential influence of polarizability and polarity on the swelling equilibrium is illustrated by comparing series of solvents and polymers with gradually changing geometrical and chemical structure. Experiments on the influence of temperature and of strain on the swelling equilibrium are reported. The swelling properties of ebonites and similar derivatives allow some conclusions on the amount of cross linking in these polymers.

Notes: This and a following article review the literature from 1910-1945 on polymerization of olefins and diolefins in suspension and emulsion, and present a number of new measurements not published to date. The subject is considered mainly from the point of view of scientific information on the mechanism of polymerization in aqueous suspensions and emulsions, but brief mention is also made of the more important disclosures in the patent literature. The new data presented in this article refer to (1) initial rates of polymerization of styrene, methyl methacrylate, vinyl acetate and acrylonitrile in aqueous suspensions and in soap emulsions as a function of catalyst concentration, temperature, and soap concentration; (2) influence of water-soluble activators, such as sodium bisulfite; (3) influence of initial size of monomer droplets on initial rates of monomer consumption; (4) study, with the aid of the electron microscope, of size of monomer droplets and polymer particles throughout polymerization; and (5) a few experiments on side reactions in the domain of higher conversions. No attempt is made in this paper to review and appraise the very large number of recent patents (from about 1930 on), which protect special procedures on the use of various promoting, regulating, or modifying ingredients. A complete digest of this practice does not exist at present, but reference may be made to the excellent chapter on emulsion polymerization in the book of Talalay and Magat (55), to the very valuable compilation of patents by Hosch in “India Rubber World” (27), and to the enumeration of a selected number of patents in the book of Scheiber (50) on pages 210-213.

Notes: In this paper it is emphasized that density is a typically macroscopic concept which cannot be transferred to small particles or bodies with small pores. This fact has not been duly accounted for in earlier work on the density of cellulose fibers. The usual interpretation of density determinations in various media is criticized and the point of view that cellulose fibers should be considered as porous bodies is dropped. The pore system occurring in native fibers is coarse enough not to interfere with density determinations in indifferent organic liquids.It is shown experimentally that even substances like water and glycerol penetrate very slowly into dry cellulose and that indifferent organic liquids do not penetrate at all. In the experiments with water vapor a new phenomenon, the heterogeneous course of absorption, is observed, giving rise to sharp microscopically visible boundary lines between the wet and the dry portion of the fiber.

Notes: Accurate determinations of the density and refractive power of various types of model filaments prepared from viscose in the bone-dry state were made. The molecular refraction, according to the formula of Gladstone and Dale, was calculated and shown to correspond within three parts per thousand with the refraction calculated from atomic refractions. It is concluded that the liquid used for the density determinations (mixtures of carbon tetrachloride and nitrobenzene) does not penetrate into the fiber substance. The technique of the experiments is described in detail. The immersion liquids used in the optical measurements were standardized mixtures of butyl stearate and tricresyl phosphate; contamination with moisture during the measurements was definitely excluded.

Notes: Nitrogen was introduced into cellulose acetate by the incorporation of amino acid groups. Some of the mixed esters were soluble in organic solvents. Cast films were examined for dyeing properties with wool-type dyes. Many of the mixed esters containing above 1% nitrogen dyed well with xylene brilliant blue, a typical wool-type dye, Mixed cellulose acetate esters were synthesized containing glycine, dl-α-alanine, β-alanine, and α-isoaminobutyric, d-glutamic, and p-aminobenzoic acids. The amino groups were protected by acetylation prior to use. The N-acetyl amino acids were treated with cellulose diacetate in dioxane solution containing chloroacetic anhydride and magnesium perchlorate as impellor and catalyst, respectively. Cellulose acetate metanilate was prepared by use of the aminosulfo acid chloride. An attempt was made to prepare 6-aminocellulose by the reaction of aqueous ammonia, and also sodamide in liquid ammonia on 6-iodotosylcellulose acetate. Only traces of nitrogen were introduced by this procedure and the recovered products showed signs of extreme degradation.

Notes: A micromethod is described for density determinations of artificial cellulose fibers by the floating method, in carbon tetrachloride in a dry and air-free atmosphere, permitting an accuracy of one part per thousand. The density is derived from the temperature at which the samples neither sink nor float. This temperature varies, with the kind of fiber, between 45° and 65°C. Measurements of the refractive power were carried out simultaneously. The refractivity calculated according to Gladstone and Dale yields slightly lower figures than those found for model fibers in the preceding communication (Part II). The average difference amounts to seven parts per thousand and is ascribed to a systematic error in the density determinations, due to a slight absorption of carbon tetrachloride by the fibers at elevated temperatures. This explanation is supported by experiments. The density of native ramie, of contracted and reoriented ramie, and of several series of rayon fibers spun with increasing stretch, is given. The conclusion is reached that the density is a measure of the percentage of crystalline substances in the fiber and it is shown that there is a correlation between density and sorptive capacity toward water vapor. The percentage of crystalline matter is estimated to be 55-60% in native ramie and 20-25% in rayon.

Notes: In the following paper the crystallization of submicroscopic cellular strands from multimolecular, cellulose films is illustrated by electron micrographs.

Notes: The ultraviolet absorption of polystyrene, with maximum absorption at 262 mμ, is due to the presence of phenyl residues in the polymer. The specific extinction coefficient is constant, i.e., independent of the molecular weight of the polymer. This shows that the extinction of the phenyl residues is additive. On the basis of this fact, it is shown that the styrene content of a butadiene-styrene copolymer (such as GR-S rubber) can be determined by ultraviolet spectrophotometry. The relative precision of the determination is about 1%, the probable relative accuracy is about 3%.

Notes: The chief result of irradiation of cellulose acetate-butyrate with ultraviolet light is cleavage of the cellulose chains so that the average molecular weight is lowered. The exposed material dissolves more slowly in common solvents than the unexposed. The acyl content and carbon and hydrogen contents are not altered appreciably. The rate of the reaction is independent of the type of common mineral impurities, the concentration of expected decomposition products, such as acetic and butyric acids, and the molecular weight of the cellulose ester. Ultraviolet light is necessary for appreciable reaction. Wave lengths shorter than 3500 Å. are most effective; longer wave lenghts are much less active.

Notes: The polymerization of dienes under the influence of heat, of diazoaminobenzene, and of benzoyl peroxide, has been studied. Diazoaminobenzene probably acts as a slow, but continuous, source of free radicals giving quantitative yields of methyl rubber of good quality from dimethylbutadiene after a few days to a few weeks at 100-125°C. The effect of diazoaminobenzene on butadiene is the same, but the rate of the uncatalyzed dimerization of butadiene at 100°C. is as fast as that of dimethylbutadiene at 150°C. and, therefore, dimerization interferes much more strongly with the polymerization of butadiene. Only 60% of polybutadiene has been obtained. A few experiments with isoprene showed its position between the two other dienes. The effect of benzoyl peroxide on the polymerization of the dienes appeared to be much smaller than was expected from its known catalytic action on the polymerization of vinyl compounds, e.g., styrene, for in this case its activity is about 100-1000 times greater than that of diazoaminobenzene. It is assumed that a larger number of radicals, produced by the fast decomposition of benzoyl peroxide, causes this difference. Diazoaminobenzene has about the same effect on the polymerization of styrene and acrylonitrile as on that of the dienes. The catalytic effect of benzoyl peroxide on the polymerization of the dienes is, on the contrary, 10,000-100,000 times smaller than on that of the vinyl compounds. This difference can be understood by the assumption that the catalyst is quickly used up by oxidizing the dienes and their polymers. While methyl rubber and the polyisoprene resemble raw natural rubber, polybutadiene, prepared under comparable conditions, is hard, swells moderately, and has a tendency to become brittle as a result of oxidation (aging). Abbreviations used are DAB (= diazoaminobenzene) and BP (= benzoyl peroxide).

Notes: The molecules of high-molecular substances, for instance, those present in rubber, can be treated statistically in two ways. On the one hand, these molecules are such complicated structures that it is possible to attribute a separate entropy and free energy to each giant molecule. On the other hand, solutions of high-molecular substances represent systems in which the single chain molecule is the elementary particle, and to which statistical considerations and concepts such as entropy and free energy can be applied. Depending upon the parameter considered, the same chain molecule must sometimes be treated as a complicated system and at other times as an elementary particle. The problems originating from the simultaneous existence of two stages in the statistical treatment are examined. It is shown that the entropy of an assembly of many chain molecules is not simply equal to the sum of the entropies of the separate chain molecules. This becomes apparent particularly when determining the distribution function with respect to a particular parameter (e.g., distance between the two end points of a molecule) from a statistical consideration of the single molecule on the one hand, and from a consideration of an assembly of identical molecules on the other hand. The relations between entropy and free energy of the individual particle and the a priori probabilities on which the treatment of an assembly is to be based are explained. It is further shown that the same particle can give rise to a macroscopic phenomenon in two ways and to approximately the same extent: first, as a complicated system, and second, as an element in a large assembly of identical particles. This applies in particular to the elastic retractive force and to the strain birefringence in rubber and related substances.

Notes: The initial rate of polymerization of highly purified styrene in bulk has been measured dilatometrically at 38.4, 56.4 and 70.1°C. For conversions up to one per cent a well-reproducible rate was observed for samples handled in complete absence of atmospheric gases. For samples saturated with air an equally reproducible, though higher rate, was observed initially. The duration of this higher rate decreases with increasing length of storage between saturation and measurement. After polymerization at higher rate, the sample continues to polymerize at the rate observed for the air-free samples.

Notes: The chemical reactivity of vinyl and diene polymers manifested during aging and degradation is similar to the reactivity manifested during polymerization; namely, the activated intermediates are radicals and the reaction proceeds by a chain mechanism. A discussion of the possible types of aggregative and disaggregative processes involved in aging is presented. On the basis that polymerization and degradation occur by means of the same radical mechanism, experimental evidence is given to indicate that under certain conditions both reactions may occur simultaneously. Viscosity changes of solutions of mono- and polystyrene and methyl methacrylate were studied under varying conditions of heat, oxygen, catalysts, light, and photosensitizers. An analysis of the concurrent aggregative and disaggregative reactions involved in aging may be obtained by isolating one reaction from the other, either by various physical methods, such as intermittent and continuous stress relaxation, or by such classical methods as sol-gel determinations and aging in solution. A comparative study of the rate of oxygen absorption of a large number of polymer types was undertaken to evaluate the factors affecting oxidation. Evidence is presented to show that these factors may be specified by the following: (1) chemical structure of the polymeric material, (2) presence of antioxidants, and (3) compounding and vulcanization. The oxidizability of polymeric materials was also studied in a circulating oxygen absorption apparatus in order to determine the effect of evolved, gaseous oxidation products. A preliminary study of the effect of light on the aging of butyl and GR-S rubber as measured by oxygen absorption and stress relaxation is presented.

Notes: The correlation between structure and properties of elastomers prepared from dienes, natural rubber, gutta-percha, as well as those of some significant derivatives of natural rubber, are discussed. The similar influence exerted by methyl groups on the brittle point, elastic recovery, and permeability to gases is demonstrated and separated from the effect caused by insertion of  - CH2 - CHR -  groups in straight-chain polybutadiene, which takes place during copolymerization or 1,2 addition. The preponderant influence of an unbranched-chain structure on tensile strength at elevated temperatures and in the swollen state is illustrated. Complex compounds with silver nitrate provide further evidence for the particular symmetry of the natural rubber chain: They are rein forcing agents for synthetic elastomers. The brittle points of hydrochlorides from natural rubber, gutta-percha, and polyisoprene are compared with those of polyvinyl compounds. Correlation between the structure of molecular units in a polymeric paraffin derivative and its elasticity is pointed out.

Notes: Various problems related to the determination with x-rays of the atomic configuration of organic fibers are discussed. Because of the approximate nature of the underlying theory, too far-reaching conclusions should be avoided, especially since, in the case of organic fibers, the situation is much less simple than in the case of sodium chloride powder or metallic wires, for example. Because of these facts, and because of the relative poorness of fiber patterns, the atomic coordinates as well as the space group of the structure can be found only within certain limits. Though the use of macroscopic models is very helpful in visualizing the spatial arrangement, no conclusions of a quantitative nature can be reached with their aid because the assumptions embodied in these models are too numerous and too inexact to justify speculations on details of the structure. In the case of cellulose fibers, it is shown that the problem cannot yet be solved completely; the outlook for a really unique solution is not hopeful. The structure proposed by Meyer and Misch is still the best approximation available. More recent propositions are shown to be less well founded; the atomic configuration introduced by Peirce, being at variance with chemical, crystallographic and x-ray evidence, is to be discarded.

Notes: Intrinsic viscosity, calculated in accordance with the empirical relation established by Schulz and Huggins, deviates considerably from its true value in the case of increasing viscosities. The introduction of a simple corrective, second degree term η2sp/150, applicable to most of the polymers, permits the direct computation of intrinsic viscosity based upon polymer solutions of various concentrations. Specific viscosities may vary to a great extent and reach a value as high as 15; the use of high concentrations permits the reduction of experimental errors and the determination, to within an average of one per cent, of the intrinsic viscosity of the polymer sample, and thus of its molecular weight.

Notes: A solvent prepared by mixing 70 parts by volume of ethanol, 30 parts of toluene, and 10 parts of water is found to be a suitable solvent for the extraction of organic nonrubber material from GR-S. The presence of the water has no effect on the rate of extraction of the nonrubber, while it reduces the extractibility of low molecular polymer to one-tenth of that found in the absence of water in the solvent. A procedure is described for the determination of small amounts of GR-S in the extracts. This procedure is based on the quantitative precipitation of the ICl addition product of the rubber from a chloroform solution by addition of ethanol. A routine procedure for the determination of the amount of rubber in GR-S is given.

Notes: A turbidimetric method has been developed for determining the styrene content in water and soap solution. The solubility of styrene in distilled water was 0.022% while in 2.0% potassium oleate solution it was 0.65 to 0.88%. The course of the polymerization of a saturated solution of styrene in 2% potassium oleate was followed by a colorimetric analysis based on reaction with dilute potassium permanganate. The rate of polymerization decreased rapidly after 50% conversion. The activation energy was estimated to be 17,000 kcal., somewhat less than in solution. The molecular weight of the polymer produced was 200,000. Occasional erratic results were ascribed to possible influence of various amounts of air sealed in the polymerization mixtures.

Notes: It has been demonstrated that the homogeneity in respect to molecular weight of emulsion copolymers of butadiene and styrene can be increased by the use of certain derivatives of n-dodecyl mercaptan rather than the mercaptan itself. These derivatives decompose and relase n-dodecyl mercaptan at an even rate during the polymerization reaction. Several new derivatives of n-dodecyl mercaptan are described.

Notes: Precise analytical methods are developed using iodine monochloride for the determination of unsaturation in polybutadiene and polyisoprene and their copolymers with styrene. The complicating side reactions, splitting out and substitution, as well as the influence of the solvent employed are investigated in detail. It is concluded that GR-S at various conversions has the theoretical unsaturation. Emulsion polybutadiene exhibits 97 to 98% of the theoretical unsaturation, emulsion polyisoprene 97% sodium polybutadiene 92%, and sodium polyisoprene 85%. The amount of unsaturation in these last two polymers as well as in the sodium copolymer of butadiene and styrene (75:25) is considerable less than theoretically expected.

Notes: Crystalline soybean trypsin inhibitor has been inactivated by ultraviolet light (λ2537 Å.) with a quantum yield of 0.0088 based upton loss of ability to inhibit the action of trypsin on casein. Inactivation involves a “one-hit” process.

Notes: Solid polyhexamethylene adipamide prepared by slow cooling of a melt is opaque as a result of formation of spherulites. Spherulites may also be formed by slow evaporation of a phenol solution of polyhexamethylene adipamide. Transparent, nonspherulitic polymer of a low degree of lateral order can be formed by cooling the polymer rapidly. Heat treatment or aging of this polymer increases the lateral order without the formation of microscopically visible spherulites. Spherulites usually reduce tensile strength, increase opacity, and decrease workability.

Notes: Die Geschwindigkeitskonstante der thermischen Polymerisation von Inden bei 150° und 175° in Abwesenheit von Sauerstoff wird zu 6.0 × 10-6 und 3.16 × 10-5 min.-1 resp., bestimmt. Der durchschnittliche mittlere Polymerisationsgrad war etwas geringer als 4 bei beiden Versuchstemperaturen.

Notes: The densities of undrawn and drawn nylon filaments (6-6 Nylon) are found to be 1.1339 and 1.1384, respectively, at 25°C. Annealing either the drawn or undrawn forms to the highest temperature possible short of melting increases the room temperature density to 1.1564, the most rapid increase in density with temperatures annealing coming at 210°C. The temperature coefficient of the density as measured at room temperature is greater for the drawn form of the nylon than the undrawn after annealing has taken place. The density of nylon calculated by Bunn and Garner from x-ray diagram data is 1.24, considerably higher than the highest value obtained by us on annealing, namely 1.156.

Notes: Eine Übersicht wird gegeben für die Argumente, die für das Vorhandensein eines regelmässigen, langperiodischen Aufbaus von Einheiten von 500 Glukoseresten in Fasercellulosen sprechen. Die Uneinheitlichkeit des Gewichtsdurchschnittes kann in ihrer Abhängigkeit vom Abbaugrad gemessen werden und nimmt viel langsamer ab als unter der Annahme von statistischer Spaltung. Die Interpretierung der kinetischen Studien mit Hilfe der Gleichung von Ekenstam führt zu zwei verschiedenen Geschwindigkeitskonstanten und Aktivierungsenergien für die Zerfallsreaktion. Schliesslich zeigen elektronenmikroskopische Aufnahmen charakteristische Unterschiede zwischen Fasern die durch Nassmahlung und durch Hydrolyse gewonnen wurden.

Notes: The inhibiting action of several phenols on the GR-S 10 (rosin soap) recipe for synthetic 2,5-Di-t-butylhydroquinone is shown to be a particularly powerful inhibitor rubber is reportor in this recipe.

Notes: An expression for the amount of chain transfer occurring in a copolymerization carried out in solvent media can be derived in a manner similar to the composition-kinetic treatment for tripolymer formation. As a result, the relative reactivity of the chain-transfer solvent can be determined.

Notes: The fine structures of emulsion polybutadiene prepared at temperatures ranging from 55°C. to -20°C. and of various butadiene-styrene copolymers prepared at -20°C. have been studied by x-ray methods. The ability of emulsion-polymerized butadiene to crystallize was found to depend to a large extent on the temperature of polymerization. Butadiene polymerized at 30°C. and above showed no evidences of crystallization when cooled unstretched to -70°C. as observed by x-ray diffraction methods; however, butadiene polymerized at 20°C. and below showed crystallization effects when cooled unstretched to -70°C. These crystallization effects became more pronounced for samples polymerized at lower temperatures. Layer-line diffraction patterns of butadiene polymerized at 30°C. and below were obtained by stretching the polymer at about 0°C. From these patterns the geometrical repeat distance along the polymer chains was found to be 5.1 ± 0.1 Å. This corresponds to a fully extended butadiene unit in the trans configuration. An anomaly was observed in the diffraction patterns of crystallizable polybutadiene stretched at 0°C. Some of the layer-line spots varied in position with per cent elongation of the sample. This suggests that the molecules in crystallites of the polymer are inclined to the stretch axis at low elongations and that they become more nearly parallel to the stretch axis at higher elongations. A small addition of styrene as comonomer at -20°C. polymerization temperature did not prevent crystallization and preferred orientation effects in the polymer, since these effects could still be found in a 90/10 charge copolymer. Larger amounts of styrene did prevent crystallinity and preferred orientation as shown by the amorphous nature of an 80/20 charge copolymer. The ability of a compounded vulcanizate of a given polymer to crystallize is less than that of the purified polymer under the same conditions. This may be due to the combined effects of milling, vulcanization, and the presence of carbon black particles in the polymer. A description of the apparatus and techniques used for cooling and stretching these polymers is given.

Notes: The rates of decomposition of benzoyl, lauroyl, bis(p-chlorobenzoyl), and bis(2,4-dichlorobenzoyl) peroxides, 0.0133 molar in styrene, have been determined at 34.8, 49.4, 61.0, 74.8, and 100°C., and the corresponding rates of polymerization of styrene have also been determined. Assuming the initial rate of polymerization of styrene, produced by benzoyl peroxide at an initial concentration of 0.0133 m./l. at each of the five temperatures used to be unity, the relative initial rates of polymerization produced by the peroxides studied are as follows: bis(2,4-dichlorobenzoyl) 2.15, lauroyl 1.52, and bis(p-chlorobenzoyl) 0.87. The rate data have been subjected to an approximate kinetic analysis, from which one may conclude that the order of intrinsic effectiveness of the peroxides as chain-initiating agents in styrene is benzoyl 〉 bis(p-chlorobenzoyl) 〉 lauroyl 〉 bis(2,4-dichlorobenzoyl), and that the effectiveness increases with increasing temperature. The activation energy for the peroxide-initiated polymerization of styrene was found to be 21 kcal. per mole. The molecular weight of polystyrene appears to be an inverse function of the temperature, the polymerization rate, the peroxide decomposition rate, and the extent of wasteful decomposition of the peroxide.

Notes: Eine Probe von Polyindol (mittleres Molekulargewicht 400) wird sorgfältig in 9 Fraktionen von steigendem Molekulargewicht von 300 bis 800 zerlegt. Die Beobachtung von Whitby und Katz, dass Bromtitrierung zu einer Doppelbindung pro Polymermolekül führt wird bestätigt. Diese Doppelbindung ist aber nicht länger zur Polymerisation fähig, da sich die Molekulargewichte verschiedener Fraktionen nicht mehr wesentlich änderten, wenn sie Polymerisationsbedingungen - Erhitzen für 500 Stunden bei 175° in Stickstoffatmosphäre - ausgesetzt wurden.

Notes: The evidence for the nature of the side chains in lignin resulting from investigations of the reactions of model substances has been summarized. The studies have involved investigation of the reactions with (a) sulfite, (b) alkali and nitrobenzene, and (c) hot alkali. (a)Reaction with sulfite occurs readily for model substances with β-hydroxyl or α,β unsaturated keto groupings (“aldol type”). Hydroxyl groups adjacent to a ring are somewhat reactive but or-hydroxyketo groupings (“acyloin type”) do not react.(b)Alkaline oxidation to aldehyde or carboxyl with nitrobenzene is effective in degrading a side chain para to a free hydroxyl group having an oxygen atom on the α-carbon atom. Conversion of the para-phenolic hydroxyl to a methyl ether neutralizes its promoting influence.(c)Cleavage to an aldehyde with hot alkali in the absence of air is specific for the “aldol type” grouping in the side chain. This is regarded as a reverse aldol condensation and it has been demonstrated that acetaldehyde can be isolated from such degradations.These results, together with the behavior of lignin and its derivatives, are interpreted in terms of probable structures for the side-chain units in lignin.

Notes: A large-scale precise fractionation of GR-S (X-55) was performed using the fractional precipitation technique at 25°C. 9 fractions, each weighing approximately 150 g. and comprising approximately 11% by weight of the original unfractionated sample, were obtained and a detailed study was made showing the effect of number-average molecular weight and related sol-gel properties on various physical and chemical properties of the crude and vulcanized fractions. Using a Santocure tread-type recipe, preliminary compounding work indicated the sulfur ratios required to give vulcanizates with 300% modulus values of 1000 p.s.i. All fractions were recompounded using these indicated optimum sulfur values. Generally, as the number-average molecular weight increased, better stress-strain and quality index data were obtained. These and other physical properties of the vulcanizates of these fractions are discussed in detail. As found in past fractionation studies pertaining to unsaturated high polymers, the higher molecular weight fractions, obtained from the unfractionated sample which was totally soluble in benzene, undergo considerable gelation when isolated and vacuum dried at 25°C. in the dark. As the indicated molecular weight of the fraction increased, higher per cent gel contents were obtained. Compared to unfractionated butadiene-styrene copolymers of similar gel contents, the gel portions of the higher molecular weight fractions had unusually high swelling indices. indicating qualitatively that the average molecular weights between points of effective cross linking in the three-dimensional gel structure were higher than those encountered in the past in unfractionated samples of similar gel contents. Other data are given pertaining to these fractions, such as the bound styrene content, per cent shrinkage of the compounded unvulcanized stocks, and the rate of gel breakdown with cold milling.

Notes: Polymere Oxydationsprodukte des Indens verhalten sich in Bezug auf Polymerisationsreaktionen wie typische Peroxyde. Ihre verhältnismässig hohe Stabilität bedingt eine relative geringe Reaktionsbeschleunigung, wobei Bruchstücke des zerfallenden Peroxyds in die polymere Molekel eintreten.

Notes: A refractometric technique for determination of second-order transition temperatures (Tm) of polymers has been extended to include a series of alkyl acrylate and methacrylate polymers with transitions at temperatures down to -50°C. A convenient technique for determining refractive index down to -75°C. is described. Certain long-chain alkyl polymers are birefringent below Tm. Correlations of brittle point with Tm and relations between viscosity and Tm are reported.

Notes: The Verdet constants of nine polyethylene glycols, three polypropylene glycols, and nine silicone polymers have been measured at 25°C. It was found that the Verdet constant increases with increase in molecular weight in each of the series, and approaches a constant value. A similar increase in the molecular magnetic rotation was noted. The results are in contrast with those on polystyrene, and the effect of end groups on the measurements is discussed in explanation.

Notes: The fundamental basis of our work is the application of statistics involving both the energy of interaction between solute and solvent molecules and the effect of steric hindrances: the statistics of freely rotating chains (sometimes called the statistics of Kuhn) are a special limiting case. Using this we can show that in the law [η] = KNα the coefficient is a function of N having a value close to 2 for small values of N, and approaching on first approximation a value of 0.5 when N increases infinitely. This statistical method has the advantage of permitting an approach to the important problem of the variation of the intrinsic viscosity as a function of the temperature T. The behavior of intrinsic viscosity with degree of polymerization and temperature as predicted by the theory check with experiment, and, in the case of the hemipolystyrenes, it has been possible to obtain very satisfactory quantitative verification. In view of numerous experiments which show that, at a given temperature, the limiting value of α for very large N is greater than 0.5, we have altered the theory of the equivalent particle accordingly. As a basis for the change the concept of porosity is examined with several other concepts, and it is shown that it is likely to apply only with reservations when the molecular structure of the solvent is taken into account.

Notes: The decrease of the limiting viscosities of unfractionated and fractionated polystyrene with time has been studied over a range of temperatures from 248 to 340°C. in vacuo. Distribution curves of several degraded samples have been determined. It has been established that the theory of random breaking of links is not applicable in the case of polystyrene. Three major deviations from the random theory have been found. The experimental results have been evaluated employing the weak link theory. The mechanisms proposed account satisfactorily for the deviations from the random theory, and give a fair representation of the experimental results, only the experimental distribution curves still showing deviations from those predicted by theory. The elementary steps for the degradation in vacuo have been discussed and the role of oxygen during polymerization has been indicated.

Notes: Additional data relating to the mechanism of the emulsion copolymerization of styrene and copolymerization of styrene and acrylonitrile are presented. These results show the influence of varying the emulsifier and of varying the water-monomer ratio upon the relationship between monomer composition and the composition of the initial copolymer molecules formed. The composition of the initial copolymer produced in emulsion is the same as that which would be predicted if polymerization occurred in the oil droplet.

Notes: Butadiene and styrene have been copolymerized by the use of sodium sand as a catalyst. The copolymers containing 75 parts of butadiene and 25 parts of styrene and made at 30° and 50° are soluble in benzene and have intrinsic viscosities ranging from 2.5 to 7.5. The copolymers has a very nearly constant composition throughout the course of the polymerization. The amount of butadiene which has entered the chain by 1,2 addition is greater than in the case of the emulsion copolymer.

Notes: Mixed cellulose acetate-ethers were prepared which contain basic-type nitrogen groups whose films were dyed by xylene brilliant blue. β-Aminoethoxylcellulose acetate was prepared from cellulose diacetate and yarn-type cellulose acetate-propionate using ethyleneimine. β-Cyanoethoxylcellulose acetate was prepared from β-cyanoethoxylcellulose and from cellulose acetate using acrylonitrile with an organic base as catalyst. The solubilities of the mixed ether-esters containing basic type nitrogen groups were less than those of cellulose esters and ethers of comparable degrees of substitution.

Notes: Whatever additional factors may be concerned in the production of good vulcanizates from natural rubber by the action of sulfur, there is no doubt that the action of sulfur on olefinic materials in general at the ordinary vulcanization temperature is a chemical one, the primary course of which is determined largely by the constitution of the olefin, and hence may be profitably studied by experimentation with olefins of different unsaturation patterns. Unaccelerated reaction between sulfur and simple monoolefins leads almost exclusively to cross linking of the separate olefin molecules, mostly in pairs, by groups of sulfur atoms. When, however, two or more olefinic units occur in the same molecule, as in the disoprenic hydrocarbons, intramolecular cross linking, i.e., cyclization, at once becomes possible, and the result of sulfur action consists partly in the cross linking of separate molecules as with the monoolefins, but largely in cyclization of the individual olefinic chains, thereby forming sulfur-containing rings. These changes entail a certain loss of unsaturation, from which deductions can be made as to the mechanism of the reaction.

Notes: Hydrogen sulfide has often been thought to play an important role in the sulfur vulcanization of natural rubber. A study has therefore been made of the reaction of hydrogen sulfide with olefins, including polyisoprenes, with special reference to the capacity of the reagent to react with olefins in the presence of free sulfur. Comparison of the products so obtained with those derived (a) by light-catalyzed reaction of hydrogen sulfide and (b) by reaction of free sulfur with polyisoprenes has greatly assisted the understanding of the course of sulfur reaction in vulcanization processes.

Notes: A series of experiments on the elastic behavior of various textile materials was carried out. All results are described with the aid of a mechanical model. For this purpose it is necessary to introduce the possibility of a blockade of a part of the model. The elastic properties are characterized by the values of seven independent fundamental constants of the model. The value of one of these constants associated with the blockade can be determined experimentally in a direct way; it is found to be independent of the moisture content. The most important properties of the model correspond with the molecular image of Hermans.

Notes: Experimental data are presented on the monomer composition of copolymers of butadiene and styrene prepared by emulsion polymerization at 50°C. The composition of the copolymers is shown to be unaffected by variations in the amount of emulsifier, of mercaptan, and of the nature of the water-soluble polymerization catalyst. The composition of the copolymers formed from a charge containing 25% styrene (by wt.) can be represented accurately over the entire conversion range by the approximate theory according to which each monomer disappears by a first order reaction with the growing chain of the polymer, without taking into account the fact that the end of the growing chain to which the monomer adds may be a radical derived from either of the two monomer molecules. If the ratio of monomers in the charge is varied within wide limits, however, it is found that the simple theory is not adequate and it is necessary to consider that the chain may end with different radicals. The analysis of the experimental data shows that a butadiene molecule adds more rapidly than a styrene molecule to a radical derived either from a butadience or a styrene molecule.

Notes: Squalene containing six isoprene units is more free of end-group effects and less limited in the range of space-distributional contortions of its carbon chain than mono- and diolefins. Hence it is more comparable with rubber than the latter group where matters of chemical reactivity are concerned. Nevertheless, in its reaction with sulfur, squalene pursues a course very similar to that followed by the diisoprene, dihydromyrcene, in that intramolecular sulfide linkages as well as intermolecular polysulfide linkages are formed. Taking into consideration the amount of sulfur which would suffice for the establishment of some given number of the simplest possible intermolecular linkages (i.e., monosulfide linkages), the efficiency of sulfur as a cross-linking reagent during the vulcanization of squalene is seen to be of a rather low order; this condition might be expected to hold for rubber in the absence of auxiliary mechanisms. So far as can be determined by direct experiment the action of sulfur in forming cross links is not essentially different from that encountered with squalene, since there are indications that both intra- and intermolecular sulfide linkages are formed - the latter being of both dialkenyl and dialkyl sulfide type, and, possibly also of alkenyl alkyl type. Under the influence of small amounts of zinc oxide or of various nitrogen-containing organic accelerators, sulfur reacts with the thiol groups of organic mercaptans forming di- and polysulfides, together with hydrogen sulfide. In the presence of rubber the same reaction occurs without actual liberation of hydrogen sulfide and it thus appears that if any thiol groups are formed as intermediates in vulcanization reactions, they will undergo ready conversion into intermolecular di- and polysulfide linkages. This may well represent an important auxiliary mechanism of cross linking.

Notes: In the emulsion polymerization of butadiene, styrene, or both, potassium persulfate is often used as the catalyst. A convenient concentration of potassium persulfate in the aqueous layer of the charge is 0.10-0.2%; the method of analysis should therefore be suitable for very small persulfate concentrations. Three methods have been investigated. In the volumetric method the persulfate is allowed to react in an acid medium with an excess of standard ferrous iron, the excess being back-titrated after a given period of time with standard ceric cerium solution. The recommended procedure was found accurate and precise within 0.5%, even at such small concentrations as 5 mg. of potassium persulfate per 100 ml. When latex is analyzed by this method, the polymer is first removed by coagulation with sulfuric acid and the persulfate determined in the filtrate. In order to obtain reliable results the reaction between the persulfate and ferrous iron in the filtrate must be carried out in the absence of oxygen, although this is not necessary in solutions of pure persulfate. The interference by oxygen is attributed to substances of peroxidic character in the fatty acid soaps used as emulsifiers in the emulsion polymerization. The colorimetric method (“Becco” method) is based upon the oxidation of the leuco base of commercial wool green BSMA to a green dye by the persulfate and (colorimetric) measurement of the dye formed. The various factors affecting the accuracy and precision of this method have been investigated and a procedure is given for the analysis of latex. For several reasons, the volumetric and polarographic methods are superior to the colorimetric method. Persulfate in a latex can be determined accurately by polarographic analysis of the latex filtrate after removal of the polymer with sulfuric acid. The polarographic determination can be carried out, in the presence of oxygen, with simple equipment. The method is rapid and precise.

Notes: An elementary theory is given for the rolling of polymeric materials, for the case in which the deformation is largely an irreversible flow of the viscous type. The theory treats the rolling process as the homogeneous deformation of volume elements over the arc of contact and neglects frictional forces that may exist at the roll surface. A numerical example is given of the calculation of roll pressure, which agrees with available data to a factor of two or better. A more complete test will require parallel measurements of viscosity and roll pressure on the same material.

Notes: By treating potato juice with acid it was found that potato globulin is converted to albumin and an insoluble casein-like protein. Potato albumin, salted out with ammonium sulfate and purified by dialysis, is very similar to ovalbumin; it is reconverted into a globulin-like protein by alkali. Solutions of potato albumin in water, as well as in acids and alkali, have a very low viscosity. Alkaline solutions of globulin have a greater viscosity than those of albumin; the viscosity numbers of the difficulty soluble protein are even greater. On the basis of the viscosity data, it was concluded that the albumin particles are corpuscular, the globulin molecules are longitudinal, and that the dissymetry is greatest for the difficulty soluble protein particles. On the basis of the different solubilities of all three proteins (which apparently have approximately the same chemical composition), it was concluded that the albumin molecule was the smallest and the difficulty soluble protein molecule the largest. An aqueous solution of potato albumin is denatured when heated to 50-60°, the viscosity thereby increasing more than 100-fold. The solutions become only slightly turbid, but do not flocculate. This unusual viscosity rise can be explained by the transformation of globular albumin molecules into fibrous, elongated particles. Only a slight viscosity increase is observed when alkaline solutions of albumin are heated. Albumin, in the presence of small amounts of salt, is precipitated at 50-60°; the salts also lower the turbidity point. However, very small concentrations of calcium chloride have a stabilizing effect. Albumin is not coagulated at room temperature by 1-2 N salt solutions. The experiments on the effect of cold on potato albumin showed that albumin, after congealing and thawing out, was more easily precipitated than the control solution. The viscosity of the cold-damaged albumin was somewhat less than that of the control solution. It was ascertained that the deaminated product of potato albumin was very similar to deaminated ovalbumin (solutions of high viscosity; linear colloid).

Notes: Polyvinyl alcohol may be reacted with methoxyacetaldehyde, 2-methoxyethoxyacetaldehyde, 2-methoxyethoxyacetaldehyde, 2-n-propoxyethoxyacetaldehyde, tetrahydrofurfuryloxyacetaldehyde, or 3-methoxypropionaldehyde, or with mixtures of these aldehydes, to yield thermoplastic resins which are soluble in cold water below specific temperatures peculiar to each resin, and which are soluble in most organic solvents except aliphatic hydrocarbons.

Notes: The refractive index-temperature data for polyvinyl acetate show a second-order phase transition temperature of 24°C.

Notes: Rubber hydrocarbon irradiated in vacuo is decomposed by ultraviolet light of wave length less than 4000 Å. The rubber very rapidly becomes insoluble, and liberates a gaseous mixture which consists mainly of hydrogen when the irradiation temperature is less than 150°C. The reaction characteristics have been investigated and point to the occurrence of dissociation processes similar to those deduced for comparable simple olefins. When irradiated above 150°C., small but significant amounts of isoprene appear in the volatile product, thereby providing an experimental means of determining the activation energy for the separation of isoprene from a polyisoprene chain terminated by an allyl radical.

Notes: The addition of silver nitrate to polymerizable systems containing butadiene can result in increased over-all rates of conversion. When butadiene is the only monomer and a cationic soap is used the addition of silver nitrate causes* a significant decrease in rate. The most active system studied was one which contained butadiene, styrene, a cationic soap, a peroxide, and silver nitrate. Comparison runs in a GR-S type formulation with silver nitrate and potassium ferricyanide indicate that the silver salt is the more effective in producing higher over-all rates of conversion.

Notes: The viscoelastic properties of plasticized Vinylite VYNW were studied over a wide range of time scale by means of the tensile creep test. A number of different plasticizers were compared as to their plasticizing effectiveness. It was found that different plasticizers imparted distinctly different shapes to the creep curve of the plasticized ferent plasticized resin. The flat creep curve, characteristic of trioctyl phosphate, is considered to be superior to the steep creep curve of tricresyl phosphate. Mixtures of plasticizers were also studied. A number of conjectures are advanced concerning the molecular mechanism of plasticizer action. One important characteristic of a plasticized formulation of the polyvinyl chloride types of resin is the existence of a three-dimensional gel structure of great permanence which prevents the occurrence of irrecoverable viscous flow.

Notes: The preparation of perbenzoic acid has been investigated in a n attempt to obtain standard solutions of perbenzoic acid suitable for the amlyszk of unsaturated compounds. Some modifiations of the procedure given by Braun for the preparation of a solution of perbenzoic acid in a n organic solvent are recommended. A study has been made of the stability of solutions of perbenzoic acid in chloroform and in benzene. Benzene or benzene-chloroform mixtures are recommended as solvents for perbenzoic acid. Chloroform solutions of perbenzoic acid which do not contain inhibitors for decomposition have been found to be definitely undesirable in analytical work because perbenzoic acid catalyzes the decomposition of chloroform by oxygen. construction Finance Corporation, in connection with the Government Synthetic Rubber Program.

Notes: The conductance of a series of salts made by the addition of n-butyl bromide to 4-vinylpyridine-styrene copolymers (1.5 to 90 mole per cent vinylpyridine) has been measured in dioxane (∊′ = 2.2), ethylene dichloride (∊′ = 10.2), and a series of nitromethane-dioxane mixtures (16.0 ≤ ∊′ ≤ 39.4). Three independent arguments deduced from the data show that ionic association under the influence of interionic electrostatic forces must occur in solutions of polyelectrolytes in such a way that a certain average fraction of the counter ions accompany the large polycation and contribute nothing to conductance. First, the conductance at fixed copolymer composition and fixed salt concentration decreases with decreasing dielectric constant of the solvent medium. Second, at a given counter ion concentration in a given solvent, the conductance decreases with increasing pyridonium content of the chain. Third, for a given salt and solvent, the conductance decreases with increasing salt concentration at a rate much slower than that characteristic of simple electrolytes.

Notes: The method for the evaluation of the percentage crystallinity in cellulose preparations from x-ray intensity measurements, previously described in detail (J. Appl. Phys., in press) is reviewed briefly and new material presented consisting of crystallinity percentages between 8% and 70%. Cotton, flax, and ramie possess equal crystallinity (70%) and so do the majority of rayons, independent of their degree of orientation and including cuprammonium and Lilienfeld rayons. Cellulose acetates saponified under varying conditions also yield almost the same value as rayon (40%). The New product Fiber G (du Pont) holds an exceptional position with 53% crystalline substance. In the series of native celluloses, wood pulp has about 65%, Valonia 65-70%, and bacterial cellulose about 40%. By dry grinding of rayon, a powder was obtained containing only slightly less than 10% crystalline substance, which on recrystallization in water, yields 2 product having the same crystallinity as rayon. The difference between the heats of wetting of the criginal and the recrystallized powder affords additional support of the results obtained.

Notes: The discrepancies in the published work on the interaction of acetone and cellulose nitrate are discussed and explained. Vapor phase adsorption isotherms for the adsorption of acetone by cellulose nitrate have been determined with an adsorption balance. They have been shown to be independent of the crystalline-amorphous ratio of the polymer but dependent upon its nitrogen content. In cellulose nitrates which are completely soluble in acetone, no limiting adsorption has been found. Adsorption analysis (a modification of chromatography) has been applied to the determination of the liquid phase adsorption by cellulose nitrate of acetone from mixtures with petroleum ether. In terms of the liquid mixture concentrations, there appears to be limited adsorption, but this is shown to be due to the nonideal nature of the solutions of acetone and petroleum ether. When allowance is made for this, the liquid and vapor phase isotherms are the same within experimental error and do not support the existence of compounds of acetone and cellulose nitrate.

Notes: By means of chain transfer agents such as dodecyl mercaptan, polyisoprenes whose number-average molecular weights range between 300-1200 and which are liquid at room temperature have been prepared. The structure and physical properties of these substances have been investigated. Vulcanization of these liquids to rubberlike materials at room temperature and above is described.