Modified plastics

Fibre reinforced and composite materials

The property profile of a plastic can be selectively altered by introducing additives or fillers designed to achieve specific characteristics. The resulting plastic compounds allow for different (usually increased) thermal, mechanical, electrical, optical or other characteristics to be enhanced beyond what is typically seen in the unmodified base polymer. The most common fillers and additives, besides colourants, are reinforcement fibres, stabilisers, and friction reducing additives.

Reinforcing fibres

In fibre reinforced polymers, the reinforcement fibres determine the compound's material properties. In many cases, the strength of the fibres is greater than the matrix materials - and frequently also higher than the tensile strength of metallic materials. The density of the most commonly used fibres, in contrast, is usually lower than that of aluminium, which allows for greater potential in designing parts for lightweight construction. In most cases, glass, carbon and aramid fibres are used in fibre reinforced plastics. From the designer's point of view, the mechanical characteristics of the material are particularly important.

Glass filled plastics

Glass fibres are the most frequently used reinforcing fibres in reinforced polymers. Compared to the base polymer, glass filled materials provide improved mechanical properties such as higher rigidity or strength and may also have improved surface hardness.

Carbon reinforced plastics

Carbon fibre reinforced polymers are extremely strong and lightweight. 

They can be expensive to produce, but are mostly used wherever high strength to weight ratio and rigidity are required. These modifications are frequently applied in fields like aerospace, automotive and many other technical applications.

Aramid fibres

Aramid fibres are a class of heat resistant and strong fibers that are used in applications where extreme requirements are imposed in terms of impact strength, material damping and abrasion resistance, and where low weight is also a requirement.

Other fillers

Other fillers generally offer no or only minimal technical benefits and primarily serve to reduce cost or weight. Ensinger offers chalk, talcum, or hollow glass spheres, for example.

Ensinger also offers ceramic filled plastics in yet another innovative compound solution that increases physical properties and machining characteristics, among other things.



Friction and abrasion reducing fillers

In addition to the well known sliding material PTFE (TeflonĀ®), the classic friction bearing materials PA and POM are also often used in their unfilled state due to their good sliding friction properties. It is possible, of course, to improve the properties of all materials, including PA and POM, in terms of their friction and wear properties, by using various additives that can be mixed into the polymer matrix. The four most common types of additive are listed here:

Graphite

Graphite is pure carbon, which, when added in finely ground form, demonstrates a significant lubricant effect. By working graphite evenly into a plastic the coefficient of friction can be reduced dramatically, especially in damp environments.

Polyethylene

The addition of polyethylene results in a similar effect as achieved when using PTFE. The frictional properties are improved, but not quite to the same degree as with PTFE. 

Molybdenum sulphide

Molybdenum sulphide is used predominantly as a nucleating agent and forms a fine crystalline structure, even when added only in small quantities. As a result of the higher crystallinity, plastics achieve greater abrasion resistance as well as a reduced coefficient of friction. Ensinger can also offer specially formulated compounds that combine low friction additives. One example is Ensinger's PVX family of materials, which contains 10% each of PTFE, graphite and carbon fibre. The combination of PTFE and graphite gives the material excellent sliding friction properties, while the addition of carbon fibres results in higher strength and abrasion resistance. These materials also offer extremely good dry and emergency running properties under heavy load.

Polytetrafluorethylene

PTFE is a high temperature resistant fluoroplastic that also has pronounced anti adhesive behaviour. Under compressive stress, abraded material from PTFE filled plastics forms a fine polymer film on the mating surfaces. This phenomenon results in very low coefficients of friction being achieved. With suitable modification, it is also possible to reduce what is referred to as stick slip effect, or avoid it altogether.

Composite material

Within the TECATEC family, Ensinger offers a PEEK composite material. TECATEC offers extreme mechanical strength and thermal dimensional stability due to the woven carbon fibre fabric that is bonded to the base PEEK polymer under pressure. It also provides high resistance to superheated steam and chemicals, making TECATEC ideal for use in medical technology applications. TECATEC is available with a content of 50 or 60% carbon fibre fabric. Its special manufacturing process achieves excellent fibre and matrix integration.