SYNOPSISThe effect of the ethylene-methylacrylate copolymer as a chemical compatibilizer in the 50 : 50 blend of low-density polyethylene (LDPE) and polydimethylsiloxane rubber (PDMS) has been studied in detail. Ethylene-methylacrylate (EMA) reacted with PDMS rubber during melt-mixing a t 180°C to form EMA-grafted PDMS rubber (EMA-g-PDMS) in situ, which acted as a compatibilizer in the LDPE-PDMS rubber blend. An optimum proportion of the compatibilizer (EMA) was found to be 6 wt % based on results of dynamic mechanical analysis, adhesion studies, and phase morphology. Lap shear adhesion between the phases increased significantly on incorporation of 6 wt % of EMA. Dynamic mechanical analysis showed a single glass transition (T,) peak at -119OC. This was further supported by Xray diffraction studies, which exhibited a remarkable increase in the degree of crystallinity and phase morphology and showed a drastic reduction in the size of the dispersed phase at the optimum concentration of EMA. 0 1993 John Wiley & Sons, Inc.

The effect of three different compatibilizers — ethylene methylacrylate copolymer (EMA), ethylene vinyl acetate copolymer (EVA), and silane grafted polyethylene (VMX) — on the physical properties, ageing behavior, thermal stability, morphology, and dynamic mechanical properties of a 50/50 blend of silicone/EPDM has been studied. Improvement in physical properties is in line with the level of technological compatibilization. Strength of adhesion for silicone-EPDM joints is significantly enhanced by the compatibilizers due to the increase in surface energy of silicone and reaction of the rubbers with the compatibilizers. Morphology study shows smaller domain size for the compatibilized blend. Dynamic mechanical analysis also reflects strong interaction of the compatibilizer with the blend components. Ageing properties are improved with the addition of the compatibilizers. Thermogravimetric analysis indicates an increase in activation energy of degradation and hence marked improvement in the thermal stability of the blends containing compatibilizer.

Experiments were carried out to study the mechanical properties of concrete modified by Carboxylated styrene-butadiene rubber (X-SBR) polymer, using mortar samples with various styrene butadiene ratios. The incorporation of X-SBR improved the mechanical properties of the concrete. The data suggest that admixing X-SBR led to denser and more refined microstructure of the cured cement mortar. Compressive strength and Flexural strength graph confirmed such improvements in the pore structure and the formation of an interpenetrating network structure of X-SBR and cement hydrate phases at relatively higher styrene butadiene ratios.