Polypropylene post-processing properties

In terms of product properties, the molecular weight distribution is an important characteristic of polymers. In the polymer industry often a post-processing step is applied to alter the molecular weight of the polymers eg, the peroxide-induced degradation of polypropylene (53). In this process, fracture of the polymer chain occurs at a random site. An alternative method is ultrasound-induced polymer scission, which involves a much better controlled, nonrandom process (7). This enables a relatively straightforward production of the desired molecular weight as well as the formation of block copolymers, as described in the previous section. 

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