MODIFICATION | WEAR RESISTANCE
Figure 9: Typical performance of different polymers in wear applications Polyamide (PA6, PA66)
Polyoxymethylene (POM) n Lower thermal stability than PA
n High shrinkage, but dimensionally stable
n Glass fibres bond poorly in matrix
n Fibres breaking out on surface cause higher abrasion
n Dimensional change of PA due to swelling has to be considered
n Compatibility of PA towards lubricants has to be checked
n Higher thermal stability than POM
Polyphenylene sulphide (PPS) n Dimensionally stable
n Shrinkage depends on crystallinity and operating temperature
n Very little water absorption
n Works very well in and under water, especially combined with carbon fibres
Source: Albis
crystalline thermoplastics are more suitable for wear applications; pairing of the same polymers in dry running applications should be avoided; smooth metallic surfaces are suitable for POM; rough metallic surfaces are more suitable for PA; glass fibre reinforcement increases abrasion on the sliding partner; electrical conductivity has to be considered when using carbon fibre.
Below: Squeaks in air vents can be prevented using new modified ABS-based grades from ELIX Polymers
Braking innovation Independent compounder Lati Industria Termo- plastici has a range of low friction and wear resistant grades branded Latilub. Luca Posca, Technical Assistance & Marketing Director with the company, says its Latilub 62-02M compound based on a modified PA6 containing MoS2
and propri-
etary lubricants has proved superior to a PA12 containing MoS2
in a cable coating for a new drum
brake for Continental Brakes Italy. The 62-02M grade has been shown to offer better heat resist- ance and also costs less.
n Appropriate for applications in medium, very good chemical resistance
Last year, ELIX Polymers introduced some new anti-noise materials for key applications, mostly but not exclusively in automotive interiors. The spe- cialty grades of regular and high-heat ABS, PC/ABS and ABS/PC are said to reduce squeak and rattle generated by the contact of plastic parts with other plastics parts, as well as with leather and other products. Typical auto parts affected by this include door handles, seating, cup holders, and air vents, according to Fabian Herter, Industry Manager Auto- motive at the company. The new grades have been submitted to
stick-slip tests according to VDA 230-206 at several automotive OEMs. These were conducted with different forces (10N, 40N) and speeds (1mm/s and 4mm/s) at several temperatures. Results are given on a 10-point scale, where 10 is the worst behav- iour, and all grades scored 1. Herter says the new compounds provide the
same key performance and processing properties as regular grades, so new approvals at OEMs are not needed. Significant cost savings are possible, he says, because fabrics or grease that have in the past been added to component systems afterwards to reduce squeak and rattle are no longer needed.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.dsmep.com �
www.tribotecc.com �
www.luh.de �
www.ltu.se (Luleå University) �
www.leeds.ac.uk (University of Leeds) �
www.omya.com �
www.wittenburggroup.com (Witcom) �
www.eurostar-ep.com �
www.sabic.com �
www.albis.com �
www.lati.com �
www.elix-polymers.com
36 COMPOUNDING WORLD | February 2020
www.compoundingworld.com
IMAGE: ELIX POLYMERS
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