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  • 11
    Electronic Resource
    Electronic Resource
    Influence of functional rubbers on the curing process of unsaturated polyester resins (1988)
    Springer
    Journal of thermal analysis and calorimetry 34 (1988), S. 441-450 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Der Einfluß einer elastomeren Zweitphase auf die Kinetik der Aushärtung und der Gelierungszeit eines als Standard dienenden ungesättigten Polyesterharzes wurden mittels isothermer und dynamischer DSC untersucht. Insbesondere wurden zwei unterschiedliche Gummis (hydroxylendständiges und isocyanatendständiges Polybutadien) untersucht, die die Kinetik der Aushärtung des Polyasterharzes in unterschiedlicher Weise beeinflussen: hydroxylendständiges Polybutadien verringert, isocyanatendständiges dagegen erhöht die Reaktionsgeschwindigkeit.
    Abstract: Резюме Используя изотермич ескую и динамическую ДСК, а также термопару, изу чено влияние эластомерно й вторичной фазы на ки нетику реакции отверждения и время гелеобразова ния обычной ненасыщенно й полиэфирной смолы. Д обавка полибутадиенового каучука с различными концевыми группами (гидроксильной и изоц ианатной) оказывает различное влияние на полную реакцию отвер ждения полиэфирной смолы: ка учук с концевой гидроксильной групп ой понижает скорость реакции, а каучук с изотиоциана тной группой — увелич ивает.
    Notes: Abstract The influence of an elastomeric second-phase on the kinetics of the curing reaction and the gel-time of a standard unsaturated polyester resin, by using the isothermal and dynamic techniques of differential scanning calorimetry (DSC) and a thermocouple was investigated. In particular we examined two different rubbers (polybutadiene hydroxyl-terminated and polybutadiene isocyanate-terminated), that, in the presence of polyester resins, affect the overall curing reaction kinetics in two ways: the former reduces the rate of reaction whilst the latter increases it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01913183
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  • 12
    Electronic Resource
    Electronic Resource
    New formulations for unsaturated polyester resins and their interactions with low-profile agents and glass fibres (1996)
    Springer
    Journal of materials science 31 (1996), S. 5135-5145 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Special anhydrides, such as hexahydrophthalic, methyl-hexahydrophthalic, nadic, methylnadic and methyl-tetrahydroxyphthalic, have been polycondensed with glycols such as propylene and di-propylene, to obtain new formulations for unsaturated polyesters. The properties of these resins, such as tensile behaviour and ultraviolet resistance, neat or mixed with anti-shrinkage additives have been examined and compared to standard polyester resins. Particular attention was paid to the study of the influence of low-profile agents on the resulting phase structures of cured systems. Moreover, the role played by the different phases on the fibre/matrix addition in composite materials reinforced with coated glass fibres was also investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00355916
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  • 13
    Electronic Resource
    Electronic Resource
    Hybrid C/Pet/epoxy composites (1995)
    Springer
    Journal of materials science 30 (1995), S. 1545-1550 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Hybrid carbon/PET/epoxy composites were prepared by a wet layup technique and characterized by standard methods of fracture and impact tests. The influence of PET fibre surface treatment with polyfunctional amine on the composite properties has been studied in order to determine the role of the fibre/matrix interface. The state of the fibre/matrix interface has been examined by several techniques, such as SEM, differential scanning calorimetry (DSC) and contact angle measurements. A significant hybrid effect of the PET/aminated fibres on the curing reaction and T g of the epoxy matrix in the composites was established. It is probably due to the reaction between the amine groups of the fibre surface and the epoxy component of the resin, as determined by DSC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375262
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  • 14
    Electronic Resource
    Electronic Resource
    Polypropylene reinforced with silicon carbide whiskers (1997)
    Springer
    Journal of materials science 32 (1997), S. 2411-2416 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thermal, crystallization and mechanical behaviour of isotactic polypropylene (iPP) reinforced with advanced silicon carbide whiskers (SiCw) has been investigated. It is well established that the existence of chemical and physical interactions between the matrix and the reinforcement enhances the cohesive strength at the interphase thus improving the mechanical performance of the composite. In order to improve chemico-physical interactions between the components of the inorganic–organic composite system, their affinity has been enhanced in two ways: by coating the whiskers with a thin layer of acrylate-grafted polydivinylbenzene and by using as matrix a chemically modified polypropylene. The mechanical properties of the resulting composite materials have been compared and related to the dispersion grade of the whiskers within the matrices and the morphology of the samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018561308695
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  • 15
    Electronic Resource
    Electronic Resource
    Review Properties of blends and composites based on poly(3-hydroxy)butyrate (PHB) and poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) copolymers (2000)
    Springer
    Journal of materials science 35 (2000), S. 523-545 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Poly(3-hydroxy)butyrate (PHB) and poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) copolymers are microbial polyesters presenting the advantages of biodegradability and biocompatibility over other thermoplastics with useful mechanical properties. However, their costs and performances must be adjusted by blending with suitable polymers. In this article the miscibility, morphology, mechanical behaviour and other prominent characteristics of a representative number of blends and composites of PHB and PHBV are summarized. In particular, blends with a few polyethers, polyesters, polyvinylacrylates and polysaccharides are illustrated. Furthermore, a brief paragraph deals with PHB/vegetal fiber composites. A wide range of properties emerges by blending with polymers having very different molecular structures and characteristics, such as crystallinity, glass transition and melting temperatures. The microstructure of the blends, resulting from thermodynamic and kinetic factors, is regarded as an important factor in controlling the mechanical and the biodegradation behaviours. Moreover, some considerations upon the nature of the “driving force” of the miscibility have been made in order to explain miscibility behaviour differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004740522751
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  • 16
    Electronic Resource
    Electronic Resource
    Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and wheat straw fibre composites: thermal, mechanical properties and biodegradation behaviour (2000)
    Springer
    Journal of materials science 35 (2000), S. 829-836 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The thermal and mechanical behaviour of a biotechnological polyester (poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) reinforced with wheat straw fibres has been investigated. In order to improve chemico-physical interactions between the components, the reinforcing agent has been previously submitted to a treatment with high temperature steam leading to fibres richer in cellulose and more reactive. The addition of straw fibres has been found to increase the rate of PHBV crystallisation, while it does not affect the crystallinity content. Furthermore, the comparison of the mechanical properties has shown that the composites exhibit higher Young moduli and lower values of both the stress (σB) and strain (∈B) to break than the neat matrix of PHBV. The biodegradability in different environments by means of short and long term tests has been studied. It has been observed that the presence of straw does not affect biodegradation rate evaluated in liquid environment and in long term soil burial tests. In the composting simulation test the rate of biodegradation is reduced for composites with more than 10% of straw content. The morphology of the composites has also been investigated and correlated to the biodegradation process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004773603516
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  • 17
    Electronic Resource
    Electronic Resource
    Measurement of branchial vascular space of trout, Oncorhynchus mykiss: effects of adrenaline (1991)
    Springer
    Journal of comparative physiology 161 (1991), S. 265-269 
    Details
    ISSN: 1432-136X
    Keywords: Fish ; Gill ; Adrenaline ; Hemodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using the isolated-perfused head preparation at a constant flow rate, hemodynamic effects of adrenaline were studied in trout gills. The calculation of the vascular spaces was performed with the isotopic pulse technique allowing measurement of the distribution space of the tracer. The results show that the branchial arterial circuit was cleared more quickly than the branchial venous and cephalic circuits. Adrenaline addition significantly increased the volume of the branchial arterial circuit at the expense of the venous circuit, illustrating the closing of arterio-venous sphincters under catecholamine control. The increase of the arterial volume could be explained by a vasodilation of the arterial circuit, rather than resulting from lamellar recruitment. Furthermore, the flow rate of the cephalic circuit represented 5% of the total branchial flow rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262307
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  • 18
    Electronic Resource
    Electronic Resource
    Effects of starvation on valine and alanine transport across the intestinal mucosal border in sea bass, Dicentrarchus labrax (1992)
    Springer
    Journal of comparative physiology 162 (1992), S. 430-435 
    Details
    ISSN: 1432-136X
    Keywords: Teleost ; Amino acid transport ; Fish intestine ; Starvation ; Sea bass, Dicentrarchus labrax
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary kinetics of intestinal transport of l-alanine and l-valine (substrates of the A-system and the L-system, respectively, in mammals) across the brush-border membrane in sea bass, Dicentrarchus labrax, were studied on intact mucosa using a short-term uptake technique. When fish were starved for 4–8 weeks, total influx (mucosa-to-cell) of valine fell owing to disappearance or modification of the diffusion component. The maximum influx rate of saturable component increased but its affinity (reflected by the Michaelis constant) decreased. Alanine transport by Na+-dependent and diffusion pathways was unchanged after starvation Fasting also induced an almost 20% decrease in the length of intestinal microvilli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00258965
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  • 19
    Electronic Resource
    Electronic Resource
    Poly(butyl acrylate) inclusive polymerization in the presence of bacterial polyesters, 1. Synthesis and preliminary mechanical and morphological characterization (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 151-160 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Lineare Polyester (PHB) aus 3-Hydroxybuttersäure und dessen Copolyester (PHBV) mit 3-Hydroxyvaleriansäure werden durch Fermentation von Glucose durch das Bakterium Alcaligenes Eutrophus hergestellt. Ihre wirtschaftliche Nutzung ist derzeit sehr eingeschränkt, bedingt durch die hohen Kosten, einen engen Verarbeitungstemperaturbereich und vor allem wegen ihrer durch die hohe Kristallinität vrursachten geringen Schlagzähigkeit bei Raumtemperatur und darunter sowie eine relativ hohe Glastemperatur.Durch “reactive blending”, d. h. Einpolymerisieren von 30 Gew.-% Butylacrylat, läßt sich PHBV schlagzäh modifizieren. Es besteht ein Zusammenhang zwischen dem mechanischen Verhalten und der Morphologie der Blends.
    Notes: Linear polyesters of 3-hydroxybutyric acid (PHB) and its copolymers with 3-hydroxyvaleric acid (PHBV) are produced by the fermentation of glucose by the bacterium Alcaligenes Eutrophus1,2. Their large-scale commerical development is severely limited, until recently, by the prohibitive cost, narrow processability window (Tdeg-Tm), and, above all, the low impact resistance around room temperature and below due to very high crystallinity and relatively high glass transition temperature.This paper reports on an attractive route to impact modification of PHBV by a reactive blending method. Interesting improvements are obtained by using 30 wt.-% of acrylate rubber. Correlations are found between mechanical response and morphology of blends.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050113
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  • 20
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    Fertilization with acrosome-reacted mouse sperm: Implications for the site of exocytosis (2011)
    National Academy of Sciences
    Details
    Publication Date: 2011-12-05
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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