Graft copolymer Tensile strength

Sarraf ef al. studied PE/PVC blends compatibilized by copolymers prepared by the ozonization and grafting technique. Tensile strength data are available from this study for 50/50 wt% composition mixtures, containing 5 wt% copol5aner (Table 2). 

A new process to develop interface vulcanization is grafting of selective accelerators onto a polymer chain, which in the subsequent process of vulcanization acts as an effective cure accelerator for the second polymer component in the blend. Beniska et al. [6] prepared SERFS blends where the polystyrene phase was grafted with the accelerator for curing SBR. Improved hardness, tensile strength, and abrasion resistance were obtained. Blends containing modified polystyrene and rw-1,4-polybutadiene showed similar characteristics as SBS triblock copolymers. 

Percent of graft copolymer Stress at 50% elongation (N/mm) Stress at 100% elongation (N/mm) Stress at 130% elongation (N/mm) Tensile strength (N/mm ) Elongation at break (%)... 

Compatibility and various other properties such as morphology, crystalline behavior, structure, mechanical properties of natural rubber-polyethylene blends were investigated by Qin et al. [39]. Polyethylene-b-polyiso-prene acts as a successful compatibilizer here. Mechanical properties of the blends were improved upon the addition of the block copolymer (Table 12). The copolymer locates at the interface, and, thus, reduces the interfacial tension that is reflected in the mechanical properties. As the amount of graft copolymer increases, tensile strength and elongation at break increase and reach a leveling off. 

The graft polymers were diluted with an SAN copolymer to 20 and 30 wt % substrate. The dry blends were mixed on a two-roll mill for a maximum of 5 minutes (165° 175°C) without added lubricants. Compression-molded samples from the milled slabs were evaluated for impact and tensile strength. Figure 5 is a schematization of this procedure. 

Tensile Strengths. Table VI contains the tensile strengths of the polyblends corresponding to the impact values of Table V. Fluctuations are small since the weight ratio of grafted copolymer to substrate is reasonably constant. Tensile strengths of the 1100 A substrate polyblends... 

Impact strength of ABS graft resins will increase with increasing particle size of the substrate latex when the substrate surface area per grafted copolymer chain is maintained at equivalent values. At 20 wt % substrate levels the increase in impact strength appears linear with increasing particle size, but at 30 wt % substrate, nonlinearity is indicated wjien the substrate particle is less than 1100 A. The inverse relationship of tensile and impact strength is preserved. 

Unexpectedly, when films were cast from these poly (vinyl chloride-g-2-ethylhexyl acrylate/acrylonitrile) solutions, they were crystal clear with very low haze values. Table IV lists some of the physical properties of these poly (vinyl chloride-g-2-ethylhexyl acrylate/acrylonitrile) cast films values for a solution blend of the acrylic copolymer and PVC are also included. While tensile strengths of the 1.0/1.5 and 1.0/4.0 acrylic copolymer/PVC-graft/blend films were about 80-90% that of the homopolymer PVC film, they were significantly higher than that of the blend polymer. Furthermore, the crescent tear strengths were higher than those of the blend and the PVC film. Most importantly, the haze values of the graft blend films were much improved over that of the blend polymer, and they more nearly approached that of the homopolymer PVC. 

---