Addition of Perbunan 26 or Perbunan 35 to a vinyl chloride resin decreases the amount of ester type plasticizers necessary to obtain equivalent or better physical proper-Tensile, lb./sq. in. 2450 2030 1380 1050 320 Ultimate elongation, % 310 360 330 375 155 Shore durometer hardness 83 83 79 73 69steam to about 280-3000 F. The resin was then fluxed about 2 minutes and allowed to mill with a rolling bank for 5 minutes with occasional cutting. To this plastic at about 280°F. was added the rubber. Mill mixing was continued for about 12 minutes at 280 °F. The batch was then sheeted off the mill at 0.075to 0.15-inch thickness.Molding Method. This operation was carried out in a standard A.S.T.M. four-cavity mold (D15-41) yielding slabs 6 X 6 X 0.075 inch. The molding cycle was 10 minutes at minimum ram pressure at 280°F ., then 10 minutes at 900 pounds per square inch at 280°F. The stock was cooled under pressurein the mold.
Molecular weight control for alfin catalyzed 1,3-diene polymers by 1,4-diene straight chain or cyclic hydrocarbons (and their derivatives) has been demonstrated. The microstructure of these moderated polymers is identical to the polymers obtained without molecular weight control. From the wide series of copolymers preparable with this improved polymerization method four were chosen for their evaluation after laboratory testing for processability, physicals, and economics. Copolymers of butadiene—isoprene (90/10 and 97/3) and butadiene—styrene (85/15 and 95/5) virgin or oil extended have been shown to be economically attractive and to give superior wear, traction, and adequate heat build up.
1. 1,3-Butadiene-acrylonitrile copolymers were mill-mixed with benzothiazoyl disulfide, sulfur, litharge, and vinyl resins, such as Vinylite (VYNW), and Saran and cured to compounds with good tensile strength, modulus, hardness, solvent resistance, and blocking temperature. 2. Results show that higher acrylonitrile type of copolymers give cured Vinylite-rubber blends with higher tensile strength, higher 100 per cent modulus, and greater ultimate elongation to break than low acrylonitrile copolymers. 3. The low temperature properties of the cured blends improve as the acrylonitrile content of the synthetic rubber is reduced. 4. An effective cure at 287° F is obtained in 15 to 30 minutes by using 2 parts of accelerator and 2 parts of sulfur per hundred parts of 1,3-butadieneacrylonitrile type copolymer-Vinylite blends. Added amounts of sulfur, and accelerator did not improve the properties or decrease the cure time at 287° F. 5. Some of the cured blends studied are free of tackiness at temperatures as high as 230° F. 6. Some stabilizers for vinyls tested as well as sodium acetate can be used to activate sulfur cures in 1,3-butadiene-acrylonitrile copolymer-Vinylite blends to formulate light-colored transparent products.
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