Molecular Structure

On the pp, how about the material Polypropylene – a polymer of propylene (propene). Polypropylene obtained by polymerizing propylene in the presence of metal catalysts, for example, Ziegler-Natta catalysts (eg, mixture of TiCl4 and AlR3): nCH2 = ch (CH3) -CH2-CH (CH3) – n settings required for polypropylene, similar to those used to make low-pressure polyethylene. In this case, depending on the particular catalyst, can receive any type of polymer or mixtures thereof. Polypropylene is available as a white powder or granules with a bulk density of 0,4-0,5 g / cm . Polypropylene is produced stable, painted and unpainted Molecular Structure by type of molecular structure can be divided into three main types: isotactic, syndiotactic and atactic.

Isotactic and syndiotactic polypropylenes are called stereoregular polymers. Isotactic polypropylene – polymers in which methyl groups are directed to one side of an imaginary plane of the main chain, syndiotactic – methyl groups are strictly alternate; atactic – methyl groups are located randomly; Physico-mechanical properties in contrast to polyethylene, polypropylene, less dense (density 0.90 g/cm3, which is the smallest value in general for all plastic), the harder (resistant to abrasion), more heat-resistant (starting soften at 140 C, the melting point of 175 C), almost never exposed to stress corrosion cracking. Has a high sensitivity to light and oxygen (the sensitivity is reduced with the introduction of stabilizers). Behavior polypropylene under tension to an even greater extent than polyethylene depends on the rate of load application and temperature. The lower the rate of expansion of polypropylene, the higher the mechanical properties.