| Amine |
chemical terminology: NH2, different types used as curatives or catalysts
|
| Angle of parallax |
make sure that the point of observation is correct or errors may occur. |
| Cheesiness |
cheesy-like feel of a casting |
| Combustible |
will burn |
| Curative |
substance used to react with the prepolymer to gel it |
| Diamine |
molecule with two amine (NH2) groups |
| Diisocyanate |
molecule with two isocyanate (NCO) groups |
| Dimer |
chemical reaction: two isocyanate groups reacted together |
| Diol |
molecule with two hydroxyl (OH) groups on it |
| Flammable |
will burn |
| Flash point |
lowest temperature at which a substance gives off combustible vapour to produce
a flash of fire if a small flame / spark is near |
| Gel |
irreversible solidification of substance; solid / reacted casting after curative is added |
| Glycol |
1,2-ethanediol; a type of diol |
| Isocyanate |
molecule with an NCO- group on it |
| Inflammable |
same as flammable; will burn |
| MDI |
chemical name: diphenylmethane diisocyanate. There are many grades |
| Meniscus |
curved upper surface of a liquid at the sides where in contact with the mould / container. This curve will remain after gellation. Measurements are read at the central flat portion. |
| Mix ratio |
the constant proportions in which the substances are mixed |
| MOCA/ MBCA |
amine curative: 4,4-methylene-bis orthochloroaniline |
| Plasticizer |
ingredient which can be added to urethane systems to modify systems but weakens the properties considerably; also used for flushing machinery or testing ratios |
| Polycaprolactone |
chemical term: similar to polyester, but with better hydrolysis resistance |
| Polyester |
chemical term: high molecular weight substances containing the ester group –O-CO- |
| Polyether |
chemical term: high molecular weight substances containing the ether group –O-
There are two types: PPG (POPG) & PTMG (PTMEG) |
| PPG / POPG |
chemical term: polypropylene glycol; low cost polyether |
| Pressure |
force applied to a surface, which is measured as force per unit area e.g. psi or bars
or pascals or Kg per square meter |
| PTMEG / PTMG |
chemical term: polytetramethylene ether glycol; high cost ether |
| Release agent |
silicone based substance / surfactant applied to mould to prevent sticking |
| Resin |
refers to blends and partially reacted urethanes, esters, ethers, isocyanates |
| Shore A/D |
measurements of hardness; shore A being the softer range, D the harder |
| Shot size |
size / weight of each dose of resin |
| Solvent |
liquid used to dissolve a substance; often used to clean machinery, often flammable |
| Stoichiometry |
the science of calculating the quantities of substances to be mixed together based on
their reactivity |
| Substrate |
the object or surface one is casting on |
| Tear resistance |
force necessary to tear a sample of urethane. Test results may vary according to the
method used. |
| Temperature |
the measurement of ‘hotness’ or ‘coldness’ of a substance |
| Tensile strength |
the breaking strength of a sample when subjected to tensile / stretching force which
is measured in force per unit area |
| Vacuum |
the absence of air, usually in a sealed container |
| Vapour |
gaseous phase of a liquid |
| Viscosity |
The resistance of fluid to flow. |
| Wet spots |
parts on the surface of a casting that are ‘wet’ usually due to poor mixing |
