Flame-retardant polypropylene (PP) sheets are plastic sheets made from PP resin. They are manufactured through processes such as extrusion, calendaring, cooling, and cutting, with various functional additives incorporated. PP is a semi-crystalline material that is harder and has a higher melting point than polyethylene (PE). Since homopolymer PP becomes brittle at temperatures above 0°C, most commercial PP materials are random copolymers (with 1–4% ethylene) or block copolymers with higher ethylene content. Compared to homopolymer PP, copolymer PP has a lower heat distortion temperature (about 100°C), lower transparency, lower gloss, and lower stiffness, but significantly better impact strength.
So, how can we distinguish the quality of flame-retardant PP sheets?
As the saying goes, "Good products speak for themselves." The same applies to flame-retardant PP sheets. Here are some practical tips for identifying high-quality PP sheets:
- Check the Surface Gloss
Poor gloss usually indicates the use of recycled plastic. - Observe Flexibility and Toughness
Sheets made from virgin materials have excellent toughness and can bend slightly without breaking. - Inspect the Cut Surface
When cutting recycled plastic, you may notice various colored impurities in the cross-section. - Check the Density
The density of polypropylene is about 0.92–0.93 g/cm³. Genuine PP sheets float on water, whereas many other plastics sink. - Test by Heating and Welding
Recycled plastic sheets often emit smoke when heated or welded, while virgin PP emits little or no smoke. - Transparency
Sheets made with recycled materials tend to have poor light transmittance. - Toughness
Recycled PP sheets generally have significantly lower toughness. - Float Test for Density
Drop the sheet into water. Virgin PP will float, while most recycled materials will sink.
These simple tests can help you identify the authenticity and quality of flame-retardant PP sheets.
