Plastics, poor high temperature

TPEs prepared from rubber-plastic blends usually show poor high-temperature properties. This problem could be solved by using high-melting plastics like polyamides and polyesters. But, often they impart processing problems to the blends. Jha and Bhowmick [49] and Jha et al. [50] have reported the development and properties of novel heat and oil-resistant TPEs from reactive blends of nylon-6 and acrylate rubber (ACM). The properties of various thermoplastic compositions are shown in Table 5.4. In this kind of blend, the plastic phase forms the continuous phase, whereas... 

Polypropylene has a chemical resistance about the same as that of polyethylene, but it can be used at 120°C (250°F). Polycarbonate is a relatively high-temperature plastic. It can be used up to 150°C (300°F). Resistance to mineral acids is good. Strong alkalies slowly decompose it, but mild alkalies do not. It is partially soluble in aromatic solvents and soluble in chlorinated hydrocarbons. Polyphenylene oxide has good resistance to ahphatic solvents, acids, and bases but poor resistance to esters, ketones, and aromatic or chlorinated solvents. 

Equipment may get washed with a steam jenny and allowed to air dry on plastic in a more remote area. We need to keep in mind that steam cleaners have the potential to cause substantial physical harm. The combination of high-pressure water and high temperatures can be dangerous. Wlien this is coupled with a worker standing on visquine or plastic, it becomes a slip, trip, and fall situation. Situations compounded with respiratory and whole-body protection, such as saranex or rubber suits and gloves, add in the potential for poor vision, heat stress, and the lack of physical dexterity. Keep these issues in mind prior to steam cleaner activity. 

Polymeric plasticizers are generally polyesters with a relatively low molecular weight. They rue used where resistance to high temperatures and freedom from migration and extraction are required. Polymeries are more difficult to incorporate, have poor low-temperature properties, and are expensive. 

Following the successful development of epoxidized soybean oil( 5), mainly as a stabilizer adjuvant with high permanence but poor low temperature plasticizing properties, the epoxidized fatty acid esters were introduced. These included the C8 mono-hydric alcohol esters — octyl epoxystearate and octyl epoxy-tallate. They also acted as stabilizer adjuvants but with outstanding low temperature plasticizing properties. The epoxy stabilizer/plasticizers have grown to over 50,000 tons/year in the U.S. in 1978, with the epoxidized soybean oil type predominating. 

Polypropylene is somewhat similar to HDPE in general properties. It exists as a homopolymer and a copolymer with ethylene and other hydrocarbons. It can also be blended with polyisobutylene. PP is one of the lowest density plastics, translucent to natural milky white with a highly crystalline structure. PP homopolymer has poor low-temperature resistance but this has largely been overcome by copolymerisation with ethylene. 

Phosphate plasticizers such as tritolyl phosphate and trixylyl phosphate are generally used where good flame resistance is required, such as in insulation and mine belting. These materials, however, are toxic and give products with poor low-temperature resistance, i.e., with a high cold flex temperature (typically, -5°C). 

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