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Digitale Medien

A rheometer for measuring the viscoelastic response of polymer melts in arbitrary planar and biaxial extensional flow fieldsBased on a paper presented at the VIIIth International Congress of Rheology, Gothenburg, Sweden (1976) (1980)

Denson, C. D. ; Hylton, D. C.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 20 (1980), S. 535-539

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ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: In this paper we describe the operation of a rheometer that is capable of measuring the viscoelastic response of a polymer melt in a biaxial or planar extensional flow field under circumstances wherein the deformation history can be varied in an arbitrary manner. The principal feature of this rheometer is the use of a closed loop feedback system to control the inflation of a flat, molten polymer sheet clamped around its periphery. The feedback system is especially designed so that either stress or strain can be used as the reference point, thus permitting the deformation history to be varied arbitrarily. Illustrative data are presented on the viscoelastic response of a molten acrylonitrile-butadiene-styrene copolymer subjected to a planar extensional flow for the following deformation histories: constant stress, constant strain, constant strain rate, oscillatory stress and oscillatory strain.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760200804

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2

Digitale Medien

Thermally stimulated creep of polyethylene, polypropylene, copolymers, and blends (1984)

Demont, P. ; Chatain, D. ; Lacabanne, C. ; [weitere]

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 24 (1984), S. 127-134

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ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The technique of Thermo Stimulated Creep (TSC) has been applied to the study of anelastic properties of polyethylene, polypropylene, their copolymers and blends. In the temperature range -200 to 100°C, complex TSC peaks were observed in all samples, namely around 0°C, about the same temperature as for the homopolypolymer polypropylene. By applying “fractional stresses”, with a convenient choice or the loading program, these peaks have been experimentally resolved. Two components can be distinguished: 1. The “low temperature” component is characterized by mechanical retardation times following a compensation law. It has been attributed to microbrownian motions of polypropylene sequences liberated at the glass transition of the “true” amorphous regions. 2. The “high temperature” component which is influenced by thermal treatment has been assigned to microbrownian motions of polypropylene sequences liberated at the glass transition of the “constrained” amorphous regions. In block polymers, an additional TSC peak is observed around -50°C: it has been associated with the glass transition of ethylene-propylene-rubber (EPR) interphase. The coupling of this interphase with polyethylene and polypropylene phases is insured by diffusion of some ethylene and propylene sequences in-EPR. At about -140°C, a TSC peak associated with the low temperature component of the glass transition of polyethylene can be distinguished in all the materials studied.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760240210

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3

Digitale Medien

Effects of residual stress and orientation on the fatigue of injection molded polysulfone (1981)

Mandell, J. F. ; Smith, K. L. ; Huang, D. D.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 21 (1981), S. 1173-1180

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ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The tensile fatigue behavior of unnotched injection molded polysulfone specimens has been investigated. The effects of orientation and residual stress were studied by comparing asmolded specimens with annealed or annealed and quenched specimens with a known residual stress pattern. The treatments are shown to have differing effects at high stresses, where failure is by shear yielding and necking, and at intermediate stresses, where failure is by fatigue crack propagation. The geometries of fatigue cracks are described for each case. An attempt is made to separate the effects of crack and craze initiation from crack propagation, and cyclic loading from cumulative time under load.

Zusätzliches Material: 8 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760211711

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4

Digitale Medien

Thermoplastic interpenetrating polymer networks of a triblock copolymer elastomer and an lonomeric plastic. II. Mechanical behavior (1981)

Siegfried, D. L. ; Thomas, D. A. ; Sperling, L. H.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 21 (1981), S. 39-46

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ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Thermoplastic interpenetrating polymer networks, IPN's, are defined as combinations of two physically crosslinked polymers. A styrene-b-ethylene-co-butylene-b-styrene (SEBS) triblock elastomer was combined with an ionomer prepared from a random copolymer of styrene, methacrylic acid, and isoprene (90/10/1 by volume), and subsequently neutralized. Two subclasses of the thermoplastic IPN's were identified. A sequential polymerization method yielded the chemically blended thermoplastic IPN's (CBT IPN's). Melt blending of the separately synthesized polymers produced the mechanically blended thermoplastic IPN's (MBT IPN's). Stress-strain and Rheovibron characterization revealed that the CBT IPN's exhibited greater tensile strength and higher elongation at break, but lower moduli than the MBT IPN materials of the same overall composition. Analysis of moduli data with the theories of Takayanagi, Davies, Budiansky, and Kerner disclosed more equal dual phase continuity for the MBT IPN's than the CBT IPN's at each composition. The low modulus of the more rubbery CBT IPN compositions was attributed to a decrease in the effective chain end-to-end distance between crosslinks in the elastomeric (EB) center block, brought about by the synthetic method.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760210107

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5

Digitale Medien

The melting behavior of a low density polyethylene powder in a screw extruder (1981)

Cox, A. P. D. ; Williams, J. G. ; Isherwood, D. P.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 21 (1981), S. 86-92

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ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: An experimental investigation into the performance in general and the melting behavior in particular of a single screw extruder running with a low density polyethylene power has been carried out and the results compared with those for a granular feedstock of low density polyethylene having similar melt properties. It was found that the tendency was for the output rate, pressure generated and specific power consumption to be lower for the powders, and that the removal of barrel heating near the feed hopper increased these parameters. Two melting mechanisms were observed in powder extrusion; one being the classic “Maddock” type, and the other such that the solid bed and melt pool were in reversed positions relative to the Maddock case. There was a trend for this latter mechanism to operate with low screw speeds, shallow channels and full heating. Melt initiation occurred nearer the feed end and melting was completed much more quickly with powders. An explanation of the mechanisms is proposed which is based on the observation of early melt initiation, and the industrial practices of feed zone cooling and increasing feed pressure generation to improve the performance of extruders running with powders are seen to be consistent with this proposition.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760210206

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6

Digitale Medien

Optimization of fiber drawing processes in terms of the filament state variables (1982)

Butler, R. H. ; Prevorsek, D. C. ; Kwon, Y. D.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 22 (1982), S. 329-344

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ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: A new method of optimizing the fiber drawing process involving the feed roll, the heated elements and the take-up roll is presented. In this method, the process is described in terms of the filament temperature and filament extension in the drawing zone. This is in contrast to the conventional approach in which the machine control variables such as the heated element temperature, fiber feed velocity and the total draw ratio were used to describe the process. It is shown that the drawing process seldom proceeds by a simple yielding mechanism and that a one-step drawing process usually involves a yield draw followed by a post-yield stretching. Using the drawing of nylon 6 fibers as an example, it is shown that the most critical factors related to achieving the highest fiber strength in drawing from a given precursor are the yarn temperature and yarn extension at yielding and during the post-yield drawing.

Zusätzliches Material: 17 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760220602

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7

Digitale Medien

Interlaminar shear properties of graphite fiber, high-performance resin compositesPresented in part at Symposium on Interfacial Interactions and Properties of Composites, Division of Organic Coating and Plastics Chemistry, American Chemical Society, Las Vegas, March 1982. (1983)

Varma, D. S. ; Needles, H. L. ; Kourtides, D. A. ; [weitere]

Brookfield, Conn. : Wiley-Blackwell

Polymer Composites 4 (1983), S. 98-103

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ISSN: 0272-8397

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Maschinenbau

Notizen: Shear properties of laminates consisting of graphite fiber (Celion 6000, Celion 3000, and T-300) and several resins (epoxy, hot melt-bismaleimide, solvent bismaleimide, polyimide, and polystyrylpyridine (PSP)) were measured using the short-beam test. The interlaminar shear strength of epoxy composites was hightest. All other resin composites showed considerably lower shear properties. The shear strengths deereased with temperature, with the loss up to 100°C being more pronounced. The PSP composites did not show a loss in strength in the temperature range investigated (room temperature to 250°C). Boiling the composite samples in water for 24 h resuled in negligible reduction in shear strength in all cases. The interlaminar shear properties depended on the fiberresin interfacial bond, the wetting characteristics of the resin, and the resin meechanical properties. Attempts were made to determine to what extent each of these factors controlled the shear properties of the composites studies. Thus, the interfacial bond between the resin and the single fiber was determined. Results showed that the lower shear strength of polyimide, bisimides and PSP composites, as compared to epoxy resin composites, seemed to be due to their corresponding low interfacial bond strengths. The subsequent decrease in shear strength with temperature appeared to be directly correlated to the decrease in bond strength. The wettability of carbon fiber tow with all these resins was also determined. The small variations in wetting characteristics of the resin did not seem to justify the rather large differences in shear-strength properties observed.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pc.750040204

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8

Digitale Medien

Fatigue of glass and carbon fiber reinforced engineering thermoplasticsPresented at 35th Annual Conf., SPI Reinforced Plastics/Composites Institute, New Orleans (February, 1980). (1981)

Mandell, J. F. ; Huang, D. D. ; McGarry, F. J.

Brookfield, Conn. : Wiley-Blackwell

Polymer Composites 2 (1981), S. 137-144

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ISSN: 0272-8397

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Maschinenbau

Notizen: Cyclic tension fatigue S-N curves are given for injection moleded Nylon 6/6, polycarbonate, polysulfone, polyphenylene sulfide, and poly(amide-imide) matrices with glass and carbon fibers as well as for unreinforced material. The S-N curves for most composites appear linear, with no evidence of a fatigue limit up to 106 cycles. Some nonlinearity is evident with the Nylon 6/6 composities, and these appear to fail at a cumulative strain similar to the ultimate static strain. The remainder of the composites appear to fail by a crack propagation mechanism. The glass reinforced materials all degrade at a similar rate in fatigue, while the carbon reinforced materials with brittle matrices degrade more slowly than do those with ductile matrices. The latter effect may be due to greater integrity of the cracked regions for brittle matrix systems.

Zusätzliches Material: 15 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pc.750020311

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9

Digitale Medien

Some effects of matrix and interface properties on the fatigue of short fiber-reinforced thermoplastics (1983)

Mandell, J. F. ; McGarry, F. J. ; Huang, D. D. ; [weitere]

Brookfield, Conn. : Wiley-Blackwell

Polymer Composites 4 (1983), S. 32-39

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ISSN: 0272-8397

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Maschinenbau

Notizen: The fatigue behavior of injection-molded tensile bars of short-fiber-reinforced theromplastics is described and related to the fatigue behavior of the matrices and the strength of the fiber/matrix interface. A brittle matrix system based on polyphenylene sulfide is shown to behave in a similar manner to long-fiber composites. Glass-fiber reinforcement in this matrix gives fatigue sensitivity that correlaes with that of unimpregnated glass fiber strands, while carbon-fiber rein-forcement gives better fatigue resistance. A well-bonded, due-tile matrix system based on nylon 6,6 gives matrix-controlled fatigue sensitivity. Fatigue data for glass- and carbon-fiber-reinfoced nylon 6,6 superimpose on the matrix fatigue data when normalized by the ultimate tensile strength. Another ductile matrix, polyetherther ketone, is very fatigue-resistant, but its composite progressively loses its reinforcing effect in fatigue, apparently due to interface failure. A transitional matrix, polysulfone, shifts from ductile to fatigue-crack-dominated failure as the cyclic stress is reduced. Its composites show an analogous failure mode shift, and the high cycle-fatigue response is correlated with fatigue-crack-growth data.

Zusätzliches Material: 11 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pc.750040106

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10

Digitale Medien

Plastic composites for electromagnetic interference shielding applications (1983)

Bigg, D. M. ; Stutz, D. E.

Brookfield, Conn. : Wiley-Blackwell

Polymer Composites 4 (1983), S. 40-46

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ISSN: 0272-8397

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Maschinenbau

Notizen: Research in the past eight years has established the ability of polymer composites made with sufficient electrical conductivity to be suitable as shields against electromagnetic interference (EMI). A number of conductive fillers have been used to produce such composites. These include carbon black, carbon fibers, metal fibers, metal flakes, and metal-coated glass fibers. Each filler offers its own set of advantages and disadvantages. An important aspect of developing polymeric composites for EMI shielding applications is measuring their shielding ability in areliable, easy-to-use test facility. Once a reliable test has been developed, basic data relating the bulk conductivity (or surface conductivity of coatings) can be generaated. The objective of this article is to discuss the relative utility of the different types of fillers commonly used, present an analysis of the utility of different testing approaches, and show data correlating volume resistivity with shielding effectiveness.

Zusätzliches Material: 14 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pc.750040107

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