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Merits & Limitations of Polychloroprene Rubber

Polychloroprene rubber is a synthetic polymer used as a substitute for natural rubber in a long list of applications that include conveyor belts, linings, hoses and as an adhesive. Each year approximately 300,000 tons of polychloroprene is consumed across the globe. Polychloroprene rubber was first industrially produced in 1932 by DuPont and is commercially known as Neoprene. Polychloroprene rubber has a distinctive balance of merits and limitations to its name, which warrants notice.

  1. Production

    • Polychloroprene rubber is produced via a polymerization process, involving the combination of chlororprene with other monomers such as methacrylic acid and 2,3 dichloro 1,3-butadiene. This is a catalytic reaction, which was once conducted using a cationic, anionic or Ziegler-Natta method, though it is more recently carried out using free radical emulsion. There are different grades of polychloroprene including normal linear, pre-crosslinked, sulfur-modified and slow crystallizing.

    Adhesive

    • One of the most prevalent uses of polychloroprene is as a contact adhesive. It is used in both a solvent and aqueous form, and its application ranges from lamination to foam bonding, and extends to use in automotive systems. When applied, components bond instantly, which enables immediate processing in the absence of any fixturing or clamping. Before polychloroprene is used as an adhesive, a metallic oxide such as zinc oxide must be added.

    Advantages

    • The abrasion and mechanical properties of polychloroprene rubber give it several advantages. It is highly resistant to oxidation via exposure to ozone or oxygenated environments, conditions that are hazardous to other rubbers. It is less susceptible to aging in extreme heat and is relatively inflammable. It also has resistance to the effects of oils, fuels and other solvents including inorganic chemicals. Its ability to adhere to various substrates allows for use as an adhesive.

    Disadvantages

    • A major disadvantage to polychloroprene rubber at one time was its high production cost. This was due to chloroprene synthesis via the acetylene process, which was very resource-intensive. Acetylene has since been replaced by the use of butadiene, thus reducing the expense. Despite its resistance to heat aging, polychloroprene degradation still occurs at temperatures above 212 degrees F. It has a considerably high water absorption rate and is poorly resistant to hydrocarbons. Some polychloroprene grades also crystallize at low temperatures.

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