Two‐ and three‐component polypropylene (PP) blends and composites were prepared to study their structure/property relationships. Butadiene‐styrene (BDS) copolymers of low compatibility formed large particles of poor adhesion in PP resulting in inferior mechanical properties. Better miscibility of ethylene‐propylene‐diene (EPDM) elastomer results in more finely dispersed particles and the experimental results indicate a transition to an interpenetrating network (IPN)– like structure with increasing elastomer content. Effective impact modification can be achieved only with EPDM elastomers of sufficient miscibility. Mutual wettability and adhesion of the components determine the structure and properties in PP/elastomer/filler systems. Modification of PP by acrylic acid grafting promotes PP/filler adhesion which, in turn, results in the separate dispersion of the components. In an unmodified PP matrix, a significant amount of the filler is encapsulated by the elastomer. At low filler content, better low temperature impact strength is achieved in the case of separately dispersed components, while encapsulation is more advantageous at high filling grades.

Polycarbonate (PC) blended with acrylonitrile-butadiene-styrene (ABS) has the maximum notched Izod impact strength, which is 58 kg cm cm 01 for PC/ABS1 and 66 kg cm cm 01 for PC/ABS2, at a ratio of 80/20 in this study. We selected the ratio of 80/20 to prepare flame-retardant PC/ABS alloys. The compatibility of flameretardant PC/ABS alloy was examined by differential scanning calorimetry (DSC). The flame-retardant PC/ABS alloy had two values of the glass transition temperature (T g ), indicating that the alloy was not compatible. Three kinds of compatibilizers, methacrylate-butadiene-styrene (MBS), ethylene-vinyl acetate (EVA), and styrene-maleic anhydride (SMA) were used to improve the phenomenon. DSC measurement revealed that after compatibilization the alloy had only one value of T g , meaning that the alloy became more compatible. Samples were frozen in liquid nitrogen to look at their morphology. We found that the domain sizes were reduced and the surface boundaries were closed and blurred, a feature that could promote the mechanical properties of the alloy. In this study, we also compared the effects of mechanical properties on differential compatibilizers for the flame-retardant PC/ABS alloy. Cycoloy 2800 is a commercial-grade flame-retardant product and was chosen to compare it with our prepared alloys in this study.

SynopsisTo improve adhesion between polypropylene (PP) and mica in PP composites, acrylic acid (AA) is graft-copolymerized onto PP by a melt-mixing method. At the same time, applying a silane coupling agent to treat the surface of inorganic filler enhances the mechanical, thermal, and electrical properties, as well as decreases mold shrinkage and color difference of the composites.

Carbon dioxide and propyleneimine were allowed to copolymerize without using any catalyst to give a polyurethane with a carbon dioxide content of 10–35 mole‐%. The polymer yield, the specific viscosity, and the content of carbon dioxide in the copolymer increased with increasing polymerization temperature. The infrared spectrum of the copolymer showed the characteristic peak assignable to a cyclic urethane(4‐methyl‐oxazolidone‐2) at 1750 cm−1 as well as the peak characteristic of the urethane linkage at 1700 cm−1. The relative intensity ratio of the former absorption to the latter decreased markedly with increasing polymerization temperature. Propyleneimine did not polymerize at all in the absence of carbon dioxide. Polymerizations were also carried out with the use of various solvents. On the basis of these results, a probable reaction scheme of the copolymerization was proposed.

A conductive plastic was compounded in a twin screw extruder by incorporating conductive carbon fiber (CF) into an acrylonitrile‐butadience‐styrene (ABS) copolymer. The effects of various processing parameters prior to injection molding were investigated; then, the electromagnetic interference shielding effectiveness (EMI SE), fiber length, processability, and mechanical properties of the composite were studied. Results showed that the EMI SE of the composite increased as the final fiber length increased. The longer final fiber was produced by feeding fibers into the ABS melt at 240°C and 60 rpm. A more conductive network was formed by adding lubricants to the composite to reduce fiber damage and increase fiber dispersion. The increase of the fiber content affected processability. When the fiber content was higher than 40 phr (parts per hundred resin) in the composite, the average fiber length shortened. This study shows that better shielding can be obtained by adding a fiber at a rate higher than 30 phr. The best shielding obtained is about 30 decibels (dB).