MATERIALS | HIGH PERFORMANCE COMPOUNDS
used for the incorporation of glass fibres are suitable for the processing of Tremin 939, with a co-rotating twin-screw extruder preferable. Systems for the incorporation of less hard fillers such as talc are also suitable for Tremin where wear protection measures are employed, it says.
Compounding care In order to maintain the length of the wollastonite needles, the company says dosing should take place downstream into the molten polymer. Moderate shear forces are sufficient for dispersion. Depending on machine conditions, 20 – 30 % by weight of Tremin 939 can be dosed “in free fall” but higher filling levels require forced dosing via a stuffing box. With PA 6T/6, the incorporation of mineral fillers significantly increases the tensile strength and modulus of elasticity with respect to unfilled PA6T/6. Trefil 1232-400 is said to be very good in terms of strength, stiffness and HDT. Tremin 939-600 AST is also good in tensile properties, but better in impact. Kaolin TEC 110 AST offers a good compromise between price and performance. PSU shows an increase in modulus of elasticity due to incorporation of mineral fillers. HPF says when using Trefil 1232-400, PSU displays more than twice the modulus of elasticity of unfilled PSU. Tremin 283-600 AST yields a very high impact strength in PSU, it says, despite the increase in the modulus of elasticity. And the heat distortion temperature is significantly increased by the incorporation of high-performance fillers. As far as PPS is concerned, modulus of elasticity is also increased by compounding with functional fillers — with Trefil 1232-400 and Tremin 939-300 AST the modulus is doubled, according to the com- pany. In addition, the mineral fillers increase the tensile strength and significantly increase the heat deflection temperature. Glass fibres have also been developed that are particularly suitable for high-performance plastics.
Table 1: Typical mechanical properties of 30% StarRov 853 in PPS (MA-510 from DIC) evaluated by roving extrusion compounding and injection moulding
Tensile Strength Tensile Modulus Flexural Strength Flexural Modulus Charpy, Notched Charpy, Unnotched
Source: Johns Manville
At Johns Manville, Plastics Technical Service Manager Michael Willis picks out Roving StarRov 853, which is characterised by its silane sizing, as the most suitable for the reinforcement of PPS/PPA/ PBT/PC/styrenic resins. It was originally developed for long fibre thermoplastics (LFT) compounding. Long glass fibre reinforced PPS has high
strength, wear resistance, high temperature resistance, and dimensional stability, which is important when considering it as an alternative to metals and thermosets for use in automotive parts (Table 1).
Above: EVs are a potential market for Lati’s latest Laramid T line of PA9T compounds
60 COMPOUNDING WORLD | November 2021
Compound interest Numerous material producers and compounders are extending their offerings in high-performance materials. BASF, for example, has expanded its Ultramid Advanced portfolio with carbon-fibre reinforced grades with loadings of 20, 30 and 40%. The company says they make for extreme light- weight parts, can safely replace aluminium and magnesium without loss in stiffness or strength, and are electrically conductive. “The new grades combine these properties with the advantages of Ultramid Advanced N, which makes them unique among carbon-fibre reinforced PPAs already available in the market: high dimensional stability due to low water uptake, excellent chemical and hydrolysis resistance, high strength and modulus,” says the company. The new grades are particularly suitable for automotive structural parts for pumps, fans, gears, and com- pressors in industrial applications, and for ultra- lightweight components in consumer electronics. Mechanical performance can be tuned by the choice and the content of the carbon fibre as well as through the additive technology. Ultra- mid Advanced N3HC8 with 40% carbon fibre content is said to show better strength and modulus at 80°C (conditioned) than either magne- sium or aluminium.
www.compoundingworld.com
132 MPa 11 GPa
211 MPa 10 GPa
13.9 kJm2 56 kJm2
IMAGE: SHUTTERSTOCK
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