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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 ).
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.
[not verified in body] The regularity of the macromolecular structure influences the degree to which it has rigid, crystalline long range order or flexible, amorphous long range disorder. [ not verified in body ] Precise knowledge of tacticity of a polymer also helps understanding at what temperature a polymer melts , how soluble it is in a ...
For crystalline or semicrystalline polymers, anisotropy plays a large role in the mechanical properties of the polymer. [7] The crystallinity of the polymer can be measured through differential scanning calorimetry. [8] For amorphous and semicrystalline polymers, as stress is applied, the polymer chains are able to disentangle and align.
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 ...
Therefore, the polypropylene product generally did not require additional purification steps to remove the atactic or low crystalline fraction. This meant that the APP supply from polypropylene plants using standard first- and early second-generation Z-N catalysts decreased as commercial plants adopted the new catalysts.
A plastic crystal is a ... In a powder pattern this intensity appears to resemble an amorphous ... The molecules that give rise to liquid crystalline behavior often ...
3.3 Amorphous plastics and crystalline plastics. 3.4 Conductive polymers. ... Between 1950 and 2017, 9.2-billion metric tons of plastic are estimated to have been ...