PE PVC PP Plastic Comparison | Performance & Burning Test | pp for plastic

PE, PVC and PP are three most widely used general thermoplastics in the plastic industry. Their molecular structures determine distinct practical performances. A simple burning experiment can quickly identify each material.

Polypropylene (pp for plastic) has the lowest density of 0.89–0.91g/cm³, ranking the lightest among all general plastics. High-isotactic PP features high crystallinity and strong rigidity.

Polyethylene is divided into two grades: LDPE (0.910–0.940g/cm³) is soft and flexible; HDPE (0.940–0.970g/cm³) delivers higher hardness and structural strength.

PVC has the maximum density. Rigid PVC ranges from 1.35 to 1.45g/cm³, while plasticized soft PVC drops to 1.20–1.35g/cm³.

PP takes the leading position in heat resistance. Its melting point is 160–170°C, allowing long-term service at 100°C and short-term resistance up to 120–150°C. It is qualified for microwave-safe food containers.

PE cannot withstand temperature over 100°C. LDPE softens and deforms under heat, so it is forbidden for microwave heating and only fits normal/low-temperature packaging.

Standard PVC softens at 75–90°C and decomposes toxic hydrogen chloride under heat. Modified CPVC improves heat resistance to 90–125°C but still cannot touch hot food directly.

PE owns the best cold resistance. HDPE keeps intact without cracking at -70°C, and LDPE maintains flexibility down to -100°C, ideal for cold pipelines and cold chain packages.

PP becomes extremely brittle below 0°C, with impact strength dropping sharply. It is not suitable for outdoor facilities in freezing winter environments.

Soft PVC gains decent low-temperature flexibility via plasticizers, but rigid PVC cracks easily in cold conditions without additives.

PP shows outstanding mechanical performance with tensile strength of 30–40MPa. It resists millions of repeated bending fractures, well-known as the “hinge plastic”.

HDPE has moderate hardness, while LDPE is soft and poor in deformation resistance, mainly applied for flexible products.

Rigid PVC reaches 40–60MPa in tensile strength, yet it is fragile and breaks quickly under cyclic bending stress.

Rigid PVC has the broadest anti-corrosion range against strong acids, alkalis, salt solutions and oils, widely adopted in industrial chemical drainage pipes.

PP ranks second in chemical resistance, stable against dilute sulfuric acid and concentrated hydrochloric acid, only damaged by fuming nitric acid and concentrated sulfuric acid.

PE resists common chemicals weakly. Strong oxidizing acid causes swelling and cracking after long-term immersion, not recommended for chemical pressure vessels.

PVC performs best in outdoor anti-aging and UV resistance. With stabilizers added, PVC pipes and cable sheaths can serve outdoors for more than 10 years.

PE outperforms PP in natural aging resistance. Farm mulch films and water supply pipes made of PE degrade slowly under sunlight with minor UV additives.

PP contains tertiary carbon on molecular chains, which accelerates oxidation when contacting copper metals. It is prone to pulverization outdoors without anti-oxidant modifiers.

High crystallinity gives PP the lowest water vapor and gas permeability, offering superior sealing for food packaging requiring oxygen and moisture isolation.

Loose molecular structure makes PE more permeable to air and water, only used for ordinary plastic bags and stretch wraps.

PVC has medium barrier properties but is rarely used in food packaging due to toxic environmental hazards.

PP requires molding temperature above 160°C with relatively high shrinkage rate, covering injection molding, fiber drawing and extrusion processes.

PE has a wide processing temperature window. LDPE has excellent film blowing performance with low production cost for plastic film manufacturing.

PVC has poor thermal stability and needs heat stabilizers during production, leading to complicated processing control.