Highlights from TPE 2005

The Eighth International Conference on TPEs, TPE 2005, was held in Berlin on the 14th and 15th September 2005. It was well attended with delegates from 21 countries covering all global regions.

The Eighth International Conference on TPEs, held in Berlin on the 14th and 15th September 2005, was well attended with delegates from 21 countries covering all global regions.

Papers were presented on new material developments, automotive applications, processing and a new session on TPEs from recycled materials.

New and improved grades continue to be developed; some are highlighted below.

Multibase (Dow Corning) has entered the highly competitive market offering a PP/EPDM (Multiflex TEV), claiming good compression set and stress relaxation performance.

For improved high temperature performance Du Pont presented process details of a 'Vamac/Hytrel' TPV launched at K2004.

The relatively soft material has been specifically developed for extruded products.

GLS has developed a nylon over-mould TPE that can be used for all nylon grades and formulations and does not need the nylon insert to be pre-dried prior to moulding.

No details of the polymer were provided other than it being a polymer alloy.

Liquid polyisobutylene can be used in SEBS formulations as a flow promoter for soft touch applications without loss in frictional performance.

Softer TPU grades are entering the market.

Elastogran now has aromatic and aliphatic versions from 65 Shore A.

Bayer now has an aromatic TPU grades from 60 Shore A.

To widen material choice within the TPE industry, the development of 'compatibilisers' is being pursued.

Kuraray has developed compatibilisers for use between polar polymers (for example, TPU) and non-polar polymers (for example SBC).

Two materials were presented: TU-Polymer, a HSBC-TPU block copolymer and 'TM-Polymer, a HSBC-PC block copolymer.

These materials were shown to have good potential for polymer modification, compatibilisation and adhesion.

BASF has developed a styrene-butadiene block copolymer, Styroflex.

It is more polar, and bridges the gap between SBS and TPV.

The product was originally developed as substitute for PVC cling film but due to its intermediate polarity it shows good compatibility and adhesion to many different polymers.

One of the difficulties of using any rubber phase in TPV elastomers is that a different crosslinking system can be required.

Dow Corning presented details of Hydrosilylation based on organosilane technology, which is well established in the rubber industry.

The product is still in development but offers improves adhesion both to the polymer matrix and to any substrate as part of two-shot moulding.

About 90% of automotive sealing applications still use EPDM.

Opportunities to introduce TPEs depend on the design and performance requirements of the seal.

In working towards TPV foams achieving the dynamic seal requirements, Trexel and Exxon Mobil Chemicals have developed a TPV grade for use with a supercritical fluid, Mucell technique.

The use of nitrogen creates a closed cell microcellular structure, which dramatically reduces water absorption and offers a better surface aspect.

One approach being used by material suppliers to introduce TPEs into sealing applications is to show test data after initial loading.

Performance is significantly improved but a change in design philosophy is required to accommodate the initial set on first loading.

For automotive airbags covers, two solutions were presented to facilitate painted surfaces to be used while still achieving the -40C deployment test criteria.

Sumitomo has developed a TPO that can be coloured in-mould and simultaneously painted.

DSM has developed a new system (paint, primer and TPV) through understanding of the material property requirements and the development and identification of appropriate test methods.

The ELV directive is driving the greater use of recycled materials but applications remain non-structural.

Vita Thermoplastic Compounds has successfully developed a TPE incorporating post-consumer polypropylene waste and tyre crumb (tread).

The final material can contain up to 80% recyclate.

The material has been accepted by the automotive industry and examples of commercial applications were presented (mud-flaps, wheel arch liners).

The grades are currently only available in black, however, Faru has developed TPEs incorporating up to 50% tyre crumb, which permits some colouring.

Limited technology was presented on the former materials, however, research from the Semenov Institute of Chemical Physics, Russia, showed that the particle size of the ground rubber has a significant influence on properties.

Particles less than 0.1mm in size offer the best mechanical and rheological properties.

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