Polypropylene is one of widely used polyolefin which its low density, excellent outstanding resistance to heat, low taste and odor and especially good chemical and solvent resistance make it differs from other commodity thermoplastics.
Some of the features which make polypropylene valuable sheet extrusion material are:
1- Light Weight:
With a specific gravity of 0.9-0.91, polypropylene has the lowest density of all the commodity thermoplastics, its high strength to weight ratio makes it attractive in many applications requiring greater rigidity than that possible using other polyolefin.
2- Heat Resistance:
Polypropylene has better heat resistance than any other low cost thermoplastics. It is suitable for continuous low stress applications up to 275°F (135°C). Also this property makes it particularly suitable for thermoforming items such as cups, trays and food containers and give it following properties:
Excellent vacuum forming properties
Excellent heat resistance, suitable to microwave oven (max. 125 C)
Material burn out non-toxicity
3- Stress Cracking:
Polypropylene is normally not susceptible to environmental stress cracking.
The “see-through” clarity properties of polypropylene are the maximum obtainable among the polyolefin. Nucleation and new clarifiers, specially in thin sheet and the final formed part enhance this clarity.
5- Solvent & Chemical Resistance:
At both elevated and ambient temperatures polypropylene exhibits excellent resistance to direct attack from non-oxidizing inorganic chemicals, detergents, low boiling hydrocarbons and alcohols. However, caution should be exercised in the presence of halogenated solvents and hydrocarbons, which may permeate and soften polypropylene. Testing to simulate extreme use conditions is strongly recommended.
Polypropylene homopolymer is widely used for sheet extrusion. However homopolymer grades favor the stiffness side of the impact/stiffness balance and becomes brittle at temperatures of 41°F (5°C) and lower. Utility at these temperatures is drastically reduced if impact resistance is required. Polypropylene impact resistant copolymers (copolymer with rubber) are recommended when greater impact strength is needed.
7- Suitable for food packaging:
The majority of polypropylene sheet production is thin sheet ( 0.5mm < thickness < 3.175mm) intended for rigid packaging application. The polypropylene used in these applications must meet FDA requirements and must have good organoleptic properties.
Polypropylene and material burn out are not toxic.
1-Cups and Food containers
3- Boxes with and without printing