1 сентября, 2015 
Pokraskin Block copolymer-based PSAs are generally extrusion-processed or melt-processed without the use of any solvents. The molecular weight of these elastomers is considerably lower than that of natural rubber. The two primary block copolymers used for PSAs are A-B-A block copolymers made from polystyrene end blocks (molecular weight 10 000-50 000) and polyisoprene or polybutadiene middle blocks (molecular weight 30 000-150 000). Typical formulations contain about 40% block copolymers, 50% hydrocarbon resin, 9% plasticizer oil, and 1% antioxidants.
Care must be taken in the selection of the resins to ensure that they are compatible with the blocks. Aromatic resins such as coumarone-indene or poly(alpha-methyl — styrene) resins are compatible with the aromatic polystyrene phase, and they may have a positive or a negative effect on the Tg of this phase. Aliphatic resins such as
terpene and rosin have a better compatibility with the middle block and thus increase tack and shear strength.
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