Replacing metal by plastic parts has two additional advantages: Plastics do not corrode, and they can be efficiently processed by injection molding into parts of highly complex shape. Production of metal parts of similar complexity is extremely time- and labor-intensive; the use of plastics in the design of complex components therefore gives design engineers and parts developers considerably greater freedom.
For durable functioning of composites, particularly under dynamic load, strong bonding between the hard and soft components is of prime importance. This is usually achieved by the use of adhesion promoters. Combinations of all standard rubber grades with most metals and suitable plastics are possible. Apart from the additional work steps needed for application of the adhesion promoter, the process requires measures for protecting against emissions of the solvents generally used, and for their environmentally correct disposal.
Bonding without Adhesion Promoters
By contrast, the plastic/rubber composites patented by Evonik (K&K composites) do not use adhesion promoters: The specialty molding compounds allow strong and durable bonding to suitable rubber mixtures without the need for special pretreatment. Composites of this type are found in a wide variety of applications, for example as shock-absorbing bearings in the chassis of motor vehicles, in switch cams, and as reinforced seals in engines and machines.
The following VESTAMID® molding compounds have been specially developed for plastic/rubber composites:
- VESTAMID® DX9321 - contains 20% glass fibers, impact modified
- VESTAMID® DX9322 - contains 15% grounded glass fibers
- VESTAMID® DX9323 - contains 35% glass fibers impact modified
- VESTAMID® DX9325 - contains 40% glass fibers, impact modified
- VESTAMID® X7099 - contains 20% glass fibers
VESTORAN® - Evonik's first POLYMER for plastic-rubber composites
1985 to 1986 the first samples of the polyphenylene ether VESTORAN® were delivered and paves the way for the market launch of plastic/rubber composites (K&K composites) patently produced without the aid of an adhesion promoter. At the K´86 plastics trade fair, this cost-effective and environmentally friendly process was brought to the attention of a large number of visitors for the first time.