Views: 1 Author: Site Editor Publish Time: 2025-11-27 Origin: Site
Flame-retardant PP is a halogen-free polypropylene material enhanced with phosphorus–nitrogen flame-retardant elements. It relies on a charring and intumescent mechanism to achieve excellent fire resistance. The material can reach UL94 V-0 ratings at 0.75 mm, 1.5 mm, and 3.0 mm, and passes GWIT 750°C and GWFI 960°C glow-wire tests. Compared with traditional flame-retardant plastics, flame-retardant PP offers low density, reduced smoke generation, and minimal mold corrosion, making it suitable for a wide range of electrical, automotive, and household applications.
Below are the six fundamental properties of flame-retardant polypropylene.
1. Mechanical Properties
Polypropylene has high crystallinity and a highly regular molecular structure, giving it excellent mechanical strength. Its tensile strength, hardness, and elasticity are all higher than those of HDPE.
One of PP’s most outstanding features is its superior flexural fatigue resistance. Living hinges made from PP can endure up to 70 million bending cycles (7×10⁷) without visible damage.
Its dry friction coefficient is also comparable to that of nylon, providing stable wear resistance.
2. Physical Properties
PP is a non-toxic, odorless, and tasteless high-crystallinity polymer with a molecular weight between 80,000 and 150,000.
Key physical characteristics include:
Low density (0.90–0.91 g/cm³) — one of the lightest plastics on the market
Highly hydrophobic — water absorption is only 0.01% after 24 hours
Excellent moldability, although the shrinkage rate is high, and thick-wall parts may sink
Good surface gloss and easy to color
3. Chemical Resistance
Polypropylene shows exceptional chemical resistance.
It is stable against most chemical reagents except concentrated sulfuric acid and concentrated nitric acid.
Low-molecular-weight aliphatic hydrocarbons, aromatics, and chlorinated solvents may soften or swell PP, but its chemical stability increases with higher crystallinity.
Due to these features, flame-retardant PP is widely used in chemical pipes, fittings, and corrosion-resistant components.
4. Thermal Performance
PP offers strong heat resistance with a melting point of 164–170°C.
Finished products can withstand sterilization above 100°C, and even at 150°C, they maintain shape without external stress.
Its brittle temperature is –35°C, and the material becomes brittle below this threshold.
5. Weatherability
Polypropylene is naturally sensitive to UV radiation.
Adding stabilizers such as zinc oxide, dilauryl thiodipropionate (DLTDP), carbon black, or similar fillers can significantly improve its aging and weather resistance.
This is crucial for outdoor flame-retardant PP applications.
6. Electrical Properties
PP exhibits excellent high-frequency electrical insulation, with a high dielectric constant that increases with temperature.
It offers:
High breakdown voltage
Strong resistance to electrical stress and arc discharge
Good performance for heated electrical insulation components
However, it can undergo accelerated aging when in direct contact with copper (known as “copper catalysis”).
Summary: Why Choose Flame-Retardant PP?
Flame-retardant PP combines light weight, mechanical strength, chemical resistance, heat stability, electrical insulation, and UL94 V-0 safety performance.
Its halogen-free formulation ensures low smoke, minimal mold corrosion, and safer processing — making it an ideal material for electrical housings, appliances, automotive parts, industrial components, and more.
NANJING HAISI is professional manufacturer of Plastic Extruder Machine, we supply Twin Screw Extruder, Single Screw Extruder, Plastic Recycling Extruder, Two Stage Extruder, Lab Scale Extruder, Mixing and Feeding Machine, Cooling and Pelletizing Machine, Crushing Machine and so on.
