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In case of atactic polypropylene, the methyl group (-CH 3) is randomly aligned, alternating (alternating) for syndiotactic polypropylene and evenly for isotactic polypropylene. This has an impact on the crystallinity (amorphous or semi-crystalline) and the thermal properties (expressed as glass transition point T g and melting point T m ).
The word plastic derives from the Greek πλαστικός (plastikos), meaning "capable of being shaped or molded;" in turn, it is from πλαστός (plastos) meaning "molded." [8] As a noun, the word most commonly refers to the solid products of petrochemical-derived manufacturing. [9]
The amorphous polyalphaolefins are synthesized by a catalyst system based on a Z-N supported catalyst and an alkyl aluminum co-catalyst. The polymerization process produces a mostly amorphous polymer with low crystallinity. Crystallinity depends on the catalyst system and on the use of co-monomers.
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.
All polymers (amorphous or semi-crystalline) go through glass transitions. The glass-transition temperature ( T g ) is a crucial physical parameter for polymer manufacturing, processing, and use. Below T g , molecular motions are frozen and polymers are brittle and glassy.
Sildenafil citrate (the active ingredient in Viagra) isn’t linked to physical addiction, meaning you won’t develop a physical dependence on it or develop withdrawal symptoms if you stop using ...
From his launch video and constantly after, the main focus of the story Stein and his campaign told was grounded in his record clearing the state’s rape kit backlog and prosecuting fentanyl crimes.
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is characteristic of a crystal. The terms " glass " and "glassy solid" are sometimes used synonymously with amorphous solid; however, these terms refer specifically to amorphous materials that undergo ...