Additives cross-linking agents

In some cases it may be desired to increase the cross-link density and hence the rigidity independently of the isocyanate-water reaction. Compounds such as glycerol, pentaerythritol and various amines have been employed as additional cross-linking agents. 

The tensile modulus of polysulphide polymers is enhanced with additional cross-linking agent and filler loading. It decreases with plasticisation. The presence of suitable reinforcing pigments gives adequate tensile and elongation properties. 

New resins, solvents, additives, cross-linking agents, and other paint components are subjected to toxicological tests to determine any possible health-hazard effects before they are used in commercial formulations. 

Hardener hard-n9r (1611) n. Additive (cross-linking agent, resin, or other modifier) used to promote or control the hardening or curing reaction of a coating, plastic, adhesive or resin system. G Harter m, F durcisseur m, S endurecedor m, I induritore m. Odian GC (2004) Principles... 

This type of material, based on hydrocolloids is generally not very resistant to water and their moisture barriers properties are poor. In some cases, water solubility or sensitivity to water is a functional advantage, e.g. for die formulation of soluble sachets to carry chemicals such as fertilisers or pesticides. For die majority of uses, the improvement of water resistance and water barrier properties is of first importance. Chemical modification of biopolymers and development of specific additives (cross linking agents or plasticisers) adapted to the polymer structure are then proposed. Regarding these developments, protein rich materials which have a non monotonous complex structure with very large potential fimctional properties are promising (Cuq et al, 1998). 

On curing, amino resins not only react with the nucleophilic sites (hydroxyl, carboxyl, amide) on the other film formers in the formulation, but also self-condense to some extent. Highly alkylated amino resins have less tendency to self-condense (33,34) and are therefore effective cross-linking agents, but may require the addition of a strong acid catalyst to obtain acceptable cure even at bake temperatures of 120—177°C. 

The manufacture of the majority of fluorocarbon elastomer gums includes the addition of an incorporated cure system comprising an organic onium cure accelerator, such as triphenylbenzylphosphonium chloride [1100-88-5] and a bisphenol cross-linking agent, such as... 

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