Elastomer Systems>>ELATOMERS-Glossary o

TermsDefinitions
ADDITIVEA material which does not take part in the chemical reaction but is included to alter the final product eg. Fillers, pigments, flame retardants etc.
CASTINGThe filling of essentially open moulds with liquid polyurethane.
CATALYSTAn ingredient in polyurethane systems which initiates a chemical reaction or increases the rate of chemical reaction.
CHAIN REACTIONLengthening of the main chain or backbone of polymer molecules by end to end attachment.
COMPONENTA separately metered stream of liquid which will be directly introduced into the mixing head.
CROSS LINKINGThe formation of chemical links between the molecular chains.
CUREA term which refers to the completeness of the chemical reaction.
CURING AGENTA component that results in chemical activity between the components, with an increase in the rate of cure.
CYCLE TIMEA term most commonly used in situations where many items are being manufactured on an automatic or semi-automatic production line. It includes the time required for mould preparation, including release agent application, dispensing of components, reaction, cure and demould.
DEGRADATIONThe deterioration of a substance caused by contact with its environment.
DEMOULD TIMEThe time between dispensing the liquid components into the mould and removing the article being produced.
DEW POINTThe temperature at which a vapour begins to condense.
ELASTOMERA flexible or semi-rigid rubber-like material not necessarily made from what is conventionally thought of as a rubber.
ELONGATIONThe increase in length of a specimen at the instant before rupture occurs. Expressed as a percent of original length.
EXOTHERMHeat generated by a chemical reaction.
FLAME RETARDANTA substance which is added to a polymer formulation to reduce or retard its tendency to burn.
HARDNESSThe surface property relating to the resistance of indentation.
HYDROXYL GROUPThe combined oxygen and hydrogen radical (-OH) which forms the reactive group in polyols.
IMPACT RESISTANCEAbility to withstand mechanical or physical blows without the loss of protective properties.
ISOCYANATEThe family name of chemical compounds having one or more NCO groups attached to the main chain.
MDIAn abbreviation for diphenylMethane Di Isocyanate.
MICROCELLULARAn elastomer of cellular or foam structure.
MILOne thousandth of an inch, 0.001 inch. A unit used to measure coating thickness.
MOULDINGThe process of producing a finished article from a closed mould.
NDINapthalene Di Isocyanate.
NCONitrogen, Carbon, Oxygen. The chemical formula for an isocyanate group.
POLYESTERPolymeric compound, with the reactive hydroxyl groups containing ester linkages.
POLYETHERPolymeric compounds with reactive hydroxyl groups containing ether linkages.
POLYMERA high molecular weight compound, natural or synthetic, whose chemical structure can be represented by a repeated small unit.
POLYOLA chemical compound with more than one reactive hydroxyl group attached to the molecule.
POST CUREThe period of cure after the product has been removed from the mould. In some cases, accelerated curing at elevated temperatures is used.
POT LIFEThe length of time after mixing together of the two components during which the polymer remains sufficiently liquid to be processed.
PREPOLYMERA chemical intermediate manufactured by reacting all the isocyanate with part or all of the polyol.
PTMEGPoly Tetra Methylene Ether Glycol
PUAbbreviation for Polyurethane.
RELEASE AGENTApplied to a mould to allow the foam to be demoulded easily.
RIMReaction Injection Moulding. A process of injecting a reacting mixture of polyurethane into a mould.
SYSTEMA rather ambiguous term used to describe almost any combination of mechanical parts or chemicals which have some relationship to each other. Often used to describe the supply of all chemical components needed to produce a polyurethane.
TDIAn abbreviation for Toluene Di Isocyanate.
THERMOSETA polymer that irreversibly cures from a liquid state to a solid state.
THERMOPLASTICA polymer that turns to a liquid when heated and freezes to a solid state when cooled.
THIXOTROPICHaving the property of decreasing viscosity with increasing shear stress. A coating is thixotropic if it thins with stirring or pumping but thickens back up when movement decreases.
VISCOSITYA measure of the thickness of a liquid. The lower the number the thinner the liquid.
VOLATILE ORGANIC COMPONENTS (VOC)Organic materials which evaporate at normal temperatures and pressures, organic materials which have vapour pressure greater than 0.1 mmHg at one atmosphere.