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Polyurethanes Information

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POLYURETHANES INTRODUCTION

Polyurethane , commonly abbreviated PU, is any polymer consisting of a chain of organic units joined by urethane (carbamate) links. Polyurethane polymers are formed through step-growth polymerization by reacting a monomer containing at least two isocyanate functional groups with another monomer containing at least two hydroxyl (alcohol) groups in the presence of a catalyst.

Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities. These materials include:

  • Low-density flexible foam used in upholstery and bedding 
  • Low-density rigid foam used for thermal insulation and RTM cores 
  • Soft solid elastomers used for gel pads and print rollers 
  • Hard solid plastics used as electronic instrument bezels and structural parts 

Polyurethanes are widely used in high resiliency flexible foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires, automotive suspension bushings, electrical potting compounds, high performance adhesives and sealants, Spandex fibers, seals, gaskets, carpet underlay, and hard plastic parts.

Polyurethane products are often called "urethanes". They should not be confused with the specific substance urethane, also known as ethyl carbamate. Polyurethanes are not produced from ethyl carbamate, nor do they contain it.

Polyurethanes are part of a very versatile group of materials that find uses in a wide range of applications, both domestic and industrial. Polyurethanes are widely used in many applications such as paints and lacquers, foam mattresses, medical implants, and industrial applications such as rollers, electrical encapsulation, engineering components, shoe soles, seals, and in the mining industry.

Polyurethanes are organic polymers that contain the urethane group in the structure. They are typically made by the reaction of a polyol with a diisocyanate.
Depending on initial reaction, the final product may require the addition of additives such as chain extenders, catalysts, and blowing agents.

By careful arrangement of the chemistry, the entire process can be carried out in one step. Polyureas are similar in reaction to polyurethanes. They are made from polyamides and not polyols. They contain urea groups in place of urethane groups.