Homopolymer and impact-modified grades

The homopolymer has a crystalline melting temperature of 168-170°C a byproduct is the non-crystallizable variant, atactic polypropylene, (contaminated with low-molecular-weight crystalline polymer), which has little commercial value. This was inevitably isolated in the diluent-based polymerization, but recent manufacture, with more discriminating catalysts, seeks to exploit the whole product. The early polypropylene was of very high molecular weight and was almost impossible to process there was even 

Sample cooled (°C min Crystallization temperature (°C) Melting temperature (°C)  

A particular application, the marine battery lid, is treated in greater detail below. Propylene-based plastics exhibit the chemical inertness associated with paraffin hydrocarbons, of which class they are high-molecular-weight members this allows their use in contact with a wide variety of liquids, both domestic and industrial. In view of their structure, propylene polymers have excellent electrical properties, including very low dielectric losses. 

On unusual feature of the structure-properties relationship is the existence of a number of crystalline forms of PP. This might have remained a scientific curiosity, except that some dyestuffs used for colouring the plastic nucleate the unusual crystalline form, the jS-form, which is associated with type III spherulites, and inferior mechanical properties. Some batches of PP, particularly propylene-ethylene sequential copolymers, have a propensity to form 

The properties detailed above lead to the following main areas of application. 

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