by Polyolefin resins have become one of the most widely used polymer families in the world. With their versatility and cost-effectiveness, polyolefin resins are utilized in a variety of applications across many industries. This article aims to provide an overview of polyolefin resins, their major types, properties, uses and production methods.
What are Polyolefin Resins?
Polyolefin resins, also known as polyolefins, are a type of plastic made from polymers of olefin monomers. The simplest olefin is ethylene (C2H4) and other common olefins used include propylene (C3H6). Polyolefin resins are produced by polymerization of simple olefins into long molecular chains. Depending on the type of monomer used, polyolefins can be classified into polyethylene, polypropylene and other variants.
Major Types of Polyolefin Resins
– Polyethylene (PE): Made from ethylene monomer, polyethylene is the most widely used plastic globally due to its versatility and low cost. It exists in several forms like LDPE, HDPE, LLDPE etc. based on polymer structure and density.
– Polypropylene (PP): Produced from propylene monomer, polypropylene is second only to PE in terms of production volumes. It has good chemical resistance and stiffness compared to PE.
– Ethylene-Vinyl Acetate (EVA): A copolymer produced by addition of vinyl acetate to ethylene during polymerization. EVA has good flexibility and clarity ideal for film and coating applications.
– Ethylene-Propylene Rubber (EPR): Also known as ethylene-propylene copolymer, EPR has properties between rubber and polyethylene. It finds use in automotive hoses, gaskets and roofing membranes due to oil and weather resistance.
Properties and Applications of Major Polyolefin Resins
Polyolefin resins are highly versatile materials with a balance of properties contributing to their extensive use across many industries globally.
Polyethylene:
– Properties: Chemical and stress crack resistance, clarity, low moisture absorption
– Applications: Food packaging films, carrier bags, bottles, pipes, wire and cable insulation
Polypropylene:
– Properties: Stiffness, heat resistance, chemical resistance, good moisture barrier
– Applications: Automotive components, living hinges, lids and caps, textiles, packaging
EVA:
– Properties: Strength, flexibility, transparency, hot tack, low temperature sealing
– Applications: Hot melt adhesives, medical devices, wire and cable jacketing, toys, boots
EPR:
– Properties: Elasticity, weather resistance, flexibility over a wide temp range
– Applications: Automotive parts, medical tubing, roofing membranes, hoses and gaskets
Production of Polyolefin Resins
Polyolefin resins are produced commercially using catalytic polymerization of olefins. The predominant method used today is gas phase polymerization over a supported chromium or Ziegler-Natta type catalyst. This allows producing polyolefins with tailored properties for specific applications. Propylene polymerization for PP also utilizes Phillips catalyst system for isotactic structure. Major polyolefin plants use fluidized bed or stirred tank reactors to achieve high polymerization rates and productivities.
With excellent balance of properties like durability, flexibility and chemical resistance coupled with low cost, polyolefin resins have emerged as one of the most useful plastic materials globally. Major types of polyolefins like PE, PP, EVA and EPR are used extensively across industries for a variety of applications. Advances in catalyst and process technologies continue to enhance polyolefin properties for more specialized uses. Going forward, polyolefin resins will remain integral plastics with increasing production volumes to meet global demand.
