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In the mid-to-late-1950s, atactic polypropylene (APP) was a by-product of the synthesis of isotactic polypropylene (iPP) using first and early second generation Ziegler–Natta catalysts (Z-N catalysts), which typically produced about 10-15 wt% of APP.
Polypropylene can be categorized as atactic polypropylene (aPP), syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP). In case of atactic polypropylene, the methyl group (-CH 3 ) is randomly aligned, alternating (alternating) for syndiotactic polypropylene and evenly for isotactic polypropylene.
ASTM D6222 / D6222M-16 Standard — Specification for Atactic Polypropylene (APP) Modified Bituminous Sheet Materials Using Polyester Reinforcements. [11] Type 1; Type 2; Grade G, surface coated granules; Grade S, smooth surface (uncoated) The Canadian Standards Association standards are: CSA A123.3 Asphalt Saturated Organic Roofing Felt
Copolymers commonly used to modify asphalt include atactic polypropylene (APP), styrene-butadiene-styrene (SBS), styrene-butadiene rubber (SBR), and styrene-ethylene-butylene-styrene (SEBS). [ 4 ] Advantages Over asphalt flat roofing systems
Atactic polymers such as polystyrene (PS) are technologically very important. [ citation needed ] If a special catalyst [ clarification needed ] is used in its synthesis, it is possible to obtain the syndiotactic version of this polymer, but most industrial polystyrene produced is atactic.
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For example, atactic polypropylene is usually amorphous and transparent while syndiotactic polypropylene, which has crystallinity ~50%, is opaque. [30] Crystallinity also affects dyeing of polymers: crystalline polymers are more difficult to stain than amorphous ones because the dye molecules penetrate through amorphous regions with greater ease.
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