Rubber blend composites physical properties

Rubbers have physical characteristics and a chemical composition that precludes their successful identification by infrared spectroscopy due to their inherent elasticity and highly filled composition. In contrast, no such difficulties are encountered with Py-GC. Crime scene rubber evidence from automotive tires and rubber vehicle components is found in hit-and-run cases and in soles of shoes worn by offenders in offenses against property. Discrimination of vehicle bumper rubbers by Py-GC has been reported. Volatile and polymeric components of rubbers and other polymers have been analyzed by Py-GC and the inorganic residue recovered for subsequent analysis. The technique may also be used to quantitate rubber blends by measuring the ratios of characteristic pyrolysis products. Figure 8.8 shows examples of the pyrograms of three common types of rubber. 

While polymer blends are used for a wide variety of purposes, those related to toughness or impact resistance constitute the largest tonnage. Similar results are seen with composites note the effect of carbon black on rubber, and glass fibers on plastics. However, specific applications depend on physical properties and morphology, treated next. 

Metallocene-based polyolefins blends can be developed which combine the performance characteristics of rubber, while maintaining a plastic s inherent ease of processibility. The extremely narrow molecular weight distributions and uniform comonomer composition result in improved and consistent physical properties. 

Polymer/sihca composite blends, not only improve the physical properties, snch as the mechanical properties and thermal properties of the materials, but they can also exhibit some unique properties that have attracted strong interest in many industries. Besides common plastics and rubber reinforcanent, many other potential and practical applications of this type of nanocomposites have been reported coatings, flame-retardant materials, optical devices, electronics and optical packaging materials, photo resist materials, photo-luminescent conducting film, per-vaporation membrane, ultra-permeable reverse-selective membranes, proton exchange membranes, grouting materials, sensors and materials for metal uptake, etc. As for the colloidal polymer/sihca nanocomposites with various morphologies, they usually exhibit enhanced, even novel, properties when compared with the traditional nanocomposites and have many potential applications in various areas. 

Wu and Chen [84] blended reclaimed rubber powder from waste tyres with fly ash and a coupling agent (aminopropyl triethoxysilane) and investigated the physical and morphological properties of the resulting blends. In addition to investigating the influence that the amount of fly ash had on these properties, they also evaluated the effect of adding different cure systems (peroxide and sulfur types) and the temperature of cure. The results showed that the fly ash was an excellent filler and could be used as a replacement for silica fillers in reclaimed rubber powder composites of this type. 

Acrylonitrile/Butadiene/Styrene (ABS) Acry-lonitrile/butadiene/styrene (ABS) polymers are not true terpolymers. As HIPS they are multipolymer composite materials, also called polyblends. Continuous ABS is made by the copolymerization of styrene and acrylonitrile (SAN) in the presence of dissolved PB rubber. It is common to make further physical blends of ABS with different amounts of SAN copolymers to tailor product properties. Similar to the bulk continuous HIPS process, in the ABS process, high di-PB (>50%, >85% 1,4-addition) is dissolved in styrene monomer, or in the process solvent, and fed continuously to a CSTR where streams of AN monomer, recycled S/AN blends from the evaporator and separation stages, peroxide or azo initiators, antioxidants and additives are continuously metered according to the required mass balance to keep the copolymer composition constant over time at steady state. 

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