Polyethylene[3]

Updated: 2026-09-16

Overview

Polyethylene (PE) is a thermoplastic polymer composed of ethylene monomer units. It accounts for over 30% of global plastic production due to its cost-effectiveness and adaptability. First synthesized in 1933, PE is classified by density: Low-Density PE (LDPE) for flexible films and High-Density PE (HDPE) for rigid containers. Its molecular structure allows for variations like Linear Low-Density PE (LLDPE) and Ultra-High Molecular Weight PE (UHMWPE), each tailored for specific industrial needs. PE is recyclable (resin ID code 2 or 4) but faces environmental challenges due to persistence in landfills.

Physical and Chemical Properties

PE’s properties vary by crystallinity and branching. LDPE (branched chains) is softer (density ~0.91 g/cm³) and more transparent, while HDPE (linear chains) is stiffer (density ~0.96 g/cm³) and opaque. Both types exhibit excellent resistance to acids, alkalis, and alcohols but swell in aromatic hydrocarbons. Thermal stability ranges up to 80°C for LDPE and 120°C for HDPE. PE is non-conductive and has low friction coefficients, making UHMWPE ideal for wear-resistant parts. Additives like antioxidants or colorants modify properties for specialized applications.

Main Applications

PE dominates packaging, with LDPE used for grocery bags and shrink wraps, while HDPE is molded into milk jugs and detergent bottles. In construction, HDPE pipes resist corrosion and are used for water/gas distribution. LLDPE enhances puncture resistance in agricultural films. Healthcare relies on sterilizable HDPE for syringes, and UHMWPE replaces metal in joint implants. Consumer goods range from toys to furniture. Recent innovations include PE composites for lightweight automotive parts and biodegradable PE blends to reduce environmental impact.

Safety and Storage

PE is generally safe under normal conditions but emits volatile organic compounds (VOCs) when heated above 200°C. Processing requires ventilation to avoid fume inhalation. Powdered PE poses dust explosion risks; static control is critical during handling. Storage should avoid direct sunlight to prevent UV degradation. Bulk PE pellets are typically stored in silos or sealed bags with desiccants. Firefighting for PE fires requires dry chemical or CO₂ extinguishers—water intensifies molten PE splatter.

B2B Procurement Guide

Buyers should specify parameters: density (e.g., 0.941 g/cm³ for HDPE), melt flow index (MFI, indicating viscosity), and regulatory compliance (e.g., FDA-approved for food contact). Custom additives (e.g., flame retardants) affect pricing and lead times. Suppliers often price by metric ton, with bulk discounts. Verify certifications like ISO 9001 and request Material Safety Data Sheets (MSDS). Regional price fluctuations occur due to ethylene feedstock costs; Asian markets often offer competitive rates for standard grades.