Blend Decreases (blend + decrease)

Distribution by Scientific Domains
Polymers and Materials Science75%

Selected Abstracts

Hydrogen-bonding interaction between poly(,-caprolactone) and low-molecular-weight amino compounds

POLYMER INTERNATIONAL, Issue 4 2001
Takumi Watanabe
Abstract The specific interactions between several low-molecular-weight diamino compounds and poly(,-caprolactone) (PCL) have been investigated by FT-IR. It was found that PCL and 3,3,-diaminodiphenylmethane (3,3,-DADPM) interact through strong intermolecular hydrogen bonds in the blend. Thermal and mechanical properties of PCL/3,3,-DADPM blends were investigated by DSC and tensile measurements, respectively. The glass transition temperature of the blend increases while both the melting point and the elongation-at-break of the blend decrease with the increase of 3,3,-DADPM content. Besides 3,3,-DADPM, several other low-molecular-weight compounds containing two amino groups, such as o -phenylenediamine or 1,6-diaminohexane, were also added into PCL and the corresponding blend systems were investigated by FT-IR and DSC. The effect of the chemical structure of the additives on the properties of PCL is discussed. © 2001 Society of Chemical Industry [source]

Viscoelastic properties of extrusion cast sheets of natural and synthetic aliphatic polyesters

POLYMER ENGINEERING & SCIENCE, Issue 10 2005
Mrinal Bhattacharya
The objective of this study was to determine the viscoelastic properties of natural (starch and protein) blends and synthetic biodegradable aliphatic copolyester blends. Blends of natural and synthetic biodegradable poly(butylene succinate) were cast into sheets using a coathanger die and then subjected to stress relaxation and creep tests at various temperatures. The natural content was varied at 10%, 30%, and 50% by weight. In some formulations a small (5% by weight) amount of compatibilizer was added. The materials were blended using a twin screw-extruder, pelletized, and sheeted using a coathanger die. The decay of stress upon the imposition of constant strain showed two regions, an exponential and power law; the stresses relaxed sharply at the initial stage and then decayed at a reduced rate for the duration of the experiment. The addition of compatibilizers increased the time required for the stress to relax compared to uncompatibilized blends of the same composition. Similarly, as the natural content increased the time taken to relax to a specified stress level decreased. Increased temperature enhanced the relaxation process. The initial strain of the creep curves was affected by the natural content; the higher the natural content, the lower the initial strain for the samples upon imposition of a constant stress. Similarly, the presence of compatibilizer in the blend reduced the initial strain for samples containing the same natural content. As the natural content of the blend decreases, the time required to attain the plateau compliance is reduced. The equilibrium compliance increased with temperature. These behaviors are described in terms of blend morphology. The empirical Struik and power law models can be used to fit the compliance data well. POLYM. ENG. SCI., 45:1452,1460, 2005. © 2005 Society of Plastics Engineers [source]

Effects of epoxy content on dynamic mechanical behaviour of PEI-toughened dicyanate,novolac epoxy blends

POLYMER INTERNATIONAL, Issue 9 2004
Dr Baochun Guo
Abstract By varying the cyanate/epoxy ratio, three polyetherimide(PEI)-modified bisphenol A dicyanate,novolac epoxy resin blends with different epoxy contents were prepared. The effects of epoxy content on the dynamic mechanical behaviour of those blends were investigated by dynamic mechanical thermal analysis. The results showed that the glass transition temperature of the cyanate,epoxy network (Tg1) in the modified blend decreases with epoxy content. When the epoxy content increases, both the width of the glass transition of the cyanate,epoxy network and its peak density are depressed substantially. Although the tangent delta peak value of PEI is basically independent of epoxy content, the Tg of PEI (Tg2) decreases with epoxy content. Tg1 is independent of the PEI loading. When Tg1 is lower than Tg2, however, the Tg1 in the blend with revised phase structure is substantially lower than other blends. Copyright © 2004 Society of Chemical Industry [source]

Optimization of physico-mechanical properties of silica-filled NR/SBR compounds

ADVANCES IN POLYMER TECHNOLOGY, Issue 4 2009
D. Salimi
Abstract In this extended study, the effect of silica reinforcement on natural rubber (NR) and NR/styrene,butadiene rubber (SBR) compounds was studied. The silica surfaces were treated with bis(3-triethoxysilylpropyl)-tetrasulfide, which is a silane-coupling agent, to chemically bond the silica to the rubber. Optimum levels of silane were determined according to the silica loading in NR compounds. Results in NR/SBR compounded with optimum levels of silane show that the cure time decreases with increasing NR content. Also, the tensile properties of the NR/SBR blends decrease with increasing SBR content. This study further confirmed that filler materials affect the physical and mechanical properties of these blends. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:224,232, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20169 [source]