In the industry there are common terminologies used to describe a particular process, material, mixture. Below is a list of terms and their meaning. Polymer is a general term used to describe rubbers and plastics. Polymers are formed from small molecules that chemically bond to other monomers. Elastomer is a general term used to describe all natural and synthetic polymeric materials, which have rubbery or elastic properties. Bloom. Many chemicals that are added to rubber have a limited solubility and if they exist in a cured rubber at levels higher than their solubility they will leach out onto the surface of the rubber. Bloom usually appears as a white or light colour deposit on the surface of the rubber. Thermoset is any material that softens on heating but then undergoes a permanent chemical change after which it is heat stable. (i.e. it will degrade on excessive heating rather than melt.) Compound is a general word used to describe a particular formulation for un-vulcanised rubber. Formulation is a term used to describe a rubber recipe. E.g. Rubber, carbon black, accelerators. Backgrinding is the breaking up of the rubber normally observed around tool split lines and gates. It results from the rubber shrinking during cure and tearing away at points, where mouldings are held. Undercure is a rubber, which has begun to undergo vulcanisation but has been removed from the mould before vulcanisation is complete. Vulcanisation is the permanent chemical change that a rubber undergoes on heating Thermoplastic is capable of being repeatedly softened by increases in temperature and hardened by decreasing the temperature. These changes are physical rather than chemical. |