Glossary - Introduction to Polymeric Composites with Rice Hulls - page 153

Formula - a list of components for the production of composites.
Formulation - working out correct quantities of chemicals/components to achieve
the desired results.
Functionality - the number of reactive groups attached to a single molecule.
G
Gas loss - net weight loss between chemicals used and final weight of foam.
Gelation rate - the speed with which chain extensions and crosslinking reactions
occur.
Gel strength - the stability of the foaming mass.
Gelling reaction - the increase in viscosity of the foaming mass caused by
polymerisation of the liquids.
Grinders - machines that produce small particles (also called shredders, cutters and
hammer mills).
H
Hand batching - the practice of weighing all ingredients by hand separately.
Hard spots - high-density areas formed in a moulded composite product.
Haze - smoke or fumes released from the foaming mass during the reaction.
Helix mixer - a mixer that uses a helical spiral mixing technique.
High shear mixer - a mixer with a blade or impeller that transfers a large amount
of mechanical energy to a chemical mix in the form of heat.
Holding tanks - storage tanks in which stable premixes are made and stored
before use.
Humid ageing - accelerated aging test for composites under high humidity and
temperature.
Hydraulic - a system by which energy is transferred from one place to another by
compression and flow of fluid.
Hydraulic mixing head - a mixing device in which the primary mixing is the
turbulence created by the flowing streams of chemical components.
Hydrophobic - water repellent.
Hydrophilic - affinity for water (composites with large open cells are more
absorptive sponges).
Hydroxyl group - the combined oxygen and hydrogen radical that forms the
reactive groups on polyols.
I
Indentation force deflection index - indicates support value of a foam based on
compression. This value is the ratio of 65% divided by 25% (compression
value). Index values >2 are considered good and values <1.75 considered poor
for urethane foam.