Plastic Properties of Polypropylene (PP)

Polypropylene (PP), a polymer prepared catalytically from propylene which differs from HDPE by having an isostatic replacement of a hydrogen atom by a methyl group on alternate carbon atoms in the main chain. Although largely unreactive chemically the presence of the methyl groups makes Polypropylene slightly more susceptible to attack by strong oxidizing agents than HDPE. A major advantage is Polypropylene’s higher temperature resistance, this makes PP particularly suitable for items such as trays, funnels, pails, bottles, carboys and instrument jars that have to be sterilized frequently for use in a clinical environment. Polypropylene is a translucent material with excellent mechanical properties and it has gradually replaced the polyethylenes for many purposes.

PP Resistance: Excellent resistance (no attack) to dilute and concentrated Acids, Alcohols, Bases and Mineral Oils. Good resistance (minor attack) to Aldehydes, Esters, Aliphatic Hydrocarbons, Ketones and Vegetable Oils. Limited resistance (moderate attack and suitable for short term use only) to Aromatic and Halogenated Hydrocarbons and Oxidizing Agents.

Polypropylene Quick Facts:

Maximum Temperature: 275°F 135°C

Minimum Temperature: 32°F 0°C

Autoclavable: Yes

Melting Point: 338°F 170°C

Tensile Strength: 4,500 psi

Hardness: R95

UV Resistance: Poor 
Translucent

Rigid

Specific Gravity: 0.90

Polypropylene Fabrication: Great chemical resistance makes Polypropylene a popular choice for plating and chemical tanks, as well as laboratory cabinetry and semi-conductor bench tops. This material machines well and is available in many profiles. Propylene is autoclaveable for usage in biohazardous environments. Other uses include fittings and connectors, storage containers, sinks, and hoods. The best joining method is hot air or nitrogen welding. Can be mechanically joined with screws or rivets. Ultrasonic inserts work well.