TECHNOLOGY | IMPACT MODIFICATION
components that require high impact resistance or feature fasteners such as snap fits.” Potential applications include connectors with snap fits, heat sinks, heat exchangers and mounting plates for electronic components. The new compounds are filled with 67-77 wt%
of an inorganic functional high thermal conductivity filler. Thermal conductivity is said to be near isotropic – virtually the same in all directions. In the direction of flow, this is 1.1 or 1.8 W/m K (Nanoflash process). Both materials are optimised with regard to flow and, as demonstrated in tests conducted in the Lanxess technical centre, are also less abrasive and gentler on tools during processing. In addition to toughness (in its conditioned
state, for example, Durethan BTC67ZH3.0EF is around five times more impact-resistant than the company’s existing Durethan BTC65H3.0EF grade), the materials also feature other good mechanical properties. The elongation at break of Durethan BTC77ZH3.0EF in its conditioned state, for exam- ple, is more than double that of the previous Durethan BTC75H3.0EF, which is filled with 75 wt% of thermally conductive mineral. This means the material can absorb more energy during deforma- tion, which in turn prevents the component from breaking so quickly under load.
Phase inversed TPO Using its Catalloy process, LyondellBasell has developed a “phase inversed” structure in its Hiflex TPO resins where the elastomer acts as the matrix and the polypropylene (PP) as the modifier for improved impact resistance. Hiflex TPO resins combine the properties of existing Hifax and Adflex
TPO resins, including easy processing, recyclability, flexibility, weatherability, weight reduction, high thermal resistance and low gloss together with improved impact, stiffness and shrinkage perfor- mance balance when used in a compound. According to the company, Hiflex TPO resins enable customers to meet challenging require- ments on performance, recyclability and process- ability as they offer an alternative to high-priced flexible polymers, engineering resins or metallo- cene polyolefin elastomers (for example, C2 C2
C4 C8 or
). Hiflex TPO resins can be used directly or as a building block in compounds for a wide variety of applications. In particular, Hiflex CA7600A is optimised for polymer modification applications, providing good compatibility with other polyolefins and a variety of other thermoplastics. It can be used as an impact modifier but can also enhance stiffness and adjust shrinkage, according to the company. It is supplied in a granule form and is said to flow well in materi- als handling systems and hopper feeders at typical ambient plant temperatures. LyondellBasell adds that its TPO resins provide
improved impact at low temperature. Unlike conventional TPOs that are mechanical blends of elastomers or plastomers in a polypropylene matrix, it says that its TPO is an alloy of rubber and polypropylene produced simultaneously in the polymerisation reactor. It claims this creates a better dispersion of the rubber in the material, which has a direct effect on the processing consist- ency and end-use properties. Compared to elastomers or plastomers, the
Catalloy family of TPO resins – which includes the Hifax, Adflex and Softell lines - do not necessarily require additional off-line blending with polypro- pylene. It says this minimises complexity and manages the risk of inconsistencies in blends. Catalloy TPO technology is also claimed to enable control of key properties such as: stiffness and impact balance; low specific gravity; thermal resistance; low-temperature flexibility; optical properties; dimensional stability; softness; compat- ibility with polyolefins; and ease of processing
Performance characteristics of the latest thermally conductive Durethan PA compounds from Lanxess, compared to previous grades Source: Lanxess
58 COMPOUNDING WORLD | April 2020
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.kraton.com �
www.milliken.com �
www.aaroninc.com �
www.mitsuichemicals.com �
www.clariant.com �
www.sabic.com �
www.lanxess.com �
www.lyondellbasell.com
www.compoundingworld.com
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