Additives, e.g. filling and reinforcing substances, can improve the properties of rubber articles or plastics. Their usage can lead to cost savings because plastic is the most expensive part. Practically all of these mostly inorganic components are only compatible with polymers after adding organosilanes. These organosilanes are able to chemically bond to the surface of filling and reinforcing substances. If these organosilanes do not possess non-functional alkyl groups, then the created hydrophobisation of surfaces is sufficient for significantly improving dispersibility. Higher process speeds, higher filling levels and in many cases even improved mechanical properties are achieved. Additional chemical bonding to the polymer is possible if silanes are functionalised with reactive organic groups. In these cases, silanes act as adhesive agents between the inorganic and organic matrix. Small quantities of silane are sufficient in order to achieve significant improvements because the bonds are chemically stable and function at a monomolecular level, a benefit already being commercially utilised in numerous applications. Meanwhile, used silane quantities significantly exceed 100,000 annual tonnes. Quantities on a scale of > 10 million tonnes/year result when calculated for compounds. The tyre industry is the leading industry in terms of quantities.
Glass fibre-reinforced plastics, in short GFP, are based on glass fibres that are treated with silanes.
Examples of filling and reinforcing substances include glass, titanium dioxide, kaolin, glimmer, aluminium and magnesium hydroxide, talcum, silicates, corundum, metal oxides or metal powder.
A whole range of physical properties can be improved with additives for the processing of polymer materials including mechanical resistance, scratch resistance, tensile strength, hardness, cohesion, ageing resistance and moisture resistance.
Additives also produce reduced water absorption of polymers and increased hydrophobia (= organophilia). Flame retardants such as Al(OH)3 or Mg(OH)2 achieve a sufficient flame delay.
Additives not only improve the end product. The manufacturing process is also optimised:
- Lower viscosity and/or higher throughput
- Simplified processing
- Reduced agglomerisation
- Higher filler content
- Lower total costs
So-called silane crosslinking is a large-scale technologically deployed variant for improving the mechanical properties of polymers. Vinylsilanes are grafted onto polymers, mostly polyethylenes or copolymerised with ethylene. The product can be crosslinked with moisture after formation. This is often used in order to improve the thermal stability of cable isolations or hot water pipes.
The usage of silanes is not just limited to thermoplastics. Artificial stones and synthetic resin concrete (epoxy, methacryl) or foundry resins (phenolic, furan resins, etc.) are typical applications for thermosetting plastics.
The addition of special silanes for catalytic propylene production creates a higher isotacticity, synonymous with increased crystallinity.