Polyethylene plastic vulcanizable

The changes in physical properties include decreased plastic flow, reduced surface tackiness, increased elasticity, much greater tensile strength, and considerably less solubility. More recently, certain thermoplastics (e.g., polyethylene) have been formulated to be vulcanizable. 

Measurements as a function of pressure are available in a few cases. Qualitatively, the speed increases as the pressure increases. Most studies have only gone as high as 200 MPa. Measurements have been made on polystyrene (122), poly(methyl methacrylate) (122), polyethylene (122), polyisobutylene (123), natural rubber vulcanizate (124), plasticized poly(vinyl chloride) (125), and poly-chlorotrifluoroethylene (67). Other measurements have been made up to 300 MPa for high density polyethylene (126), and up to 500 MPa for poly(methyl methacrylate) (127). Fiually, measiu-ements to 1 GPa have been made for polystyrene (126) and poly(methyl methacrylate) (128). For the latter, dwi/dp = 2.66 m/(s MPa) and d s/dp = 1.07 m/(s MPa). 

For many years chlorinated polyethylenes have been used mainly as additives to PVC. However in the 1970s rubber grades were introduced (e.g. Hostaprene—Hoechst, Dow CM—Dow Chemical). The polymers are cross-linked by peroxides, such as dicumyl peroxide, and plasticized with plasticizers of the types commonly used with PVC, e.g. diisooctyl phthalate. The vulcanizates are claimed to provide heat resistance in air and oil at temperatures up to 150 C at a lower cost than possible with older established polymers. 

Measurements as a function of pressure are available in a few cases. Qualitatively, the speed increases as the pressure increases. Most studies have only gone as high as 200 MPa. Measurements have been made on polystyrene (122), poly(methyl methacrylate) (122), polyethylene (122), polyisobutylene (123), natural rubber vulcanizate (124), plasticized poljKvinyl chloride) (125), and... 

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