MATERIALS | REINFORCING FIBRES
Figure 3: The effect on impact strength of PP of coupling agent used with different glass fibre grades Source: Owens Corning
Figure 4: Graph showing key performance characteristics of Hydrosize Link coupling agent grades U470 and U480 in a PA composite formulation Source: Michelman
polyamides used in engine compartment applica- tions achieve necessary resistance to hydrolysis and glycols, providing improvements in impact perfor- mance, fatigue resistance, and also colour stability. Hydrostrand 276, meanwhile, supports the move to vehicle electrification as a reinforcement for PBT used in connectors, sensors and the like. Gende- bien discussed the improvements in the mechani- cal performance of PP compounds possible with grades like CS248 and Performax 249. He pointed out how it is possible to use much less coupling agent than with alternative grades to achieve the same impact strength (Figure 3).
Additives advance The interface between matrix and reinforcement is critical in any successful reinforcement application,
44 COMPOUNDING WORLD | October 2017
contributing hugely to immediate and long term performance. Michelman, which specialises in surface additives and polymeric binders, says its newest portfolio of polyurethane film formers, Hydrosize Link, meet under-the-hood challenges faced by PA-based composites, particularly in terms of long-term resistance to hydrolysis and to ethylene glycol solutions at high temperatures. They are added during the fibre manufacturing process and are activated during compounding to increase the interfacial adhesion between the fibre and polymer matrix (Figure 4). Michelman also highlights a broad array of sizing solutions formulated for use with reclaimed and recycled carbon fibre. These include Hydrosize grades U2-04, HP3-02 and PA845H. It says the formulations are compatible with most common thermoplastics. BYK is another company offering surface enhancement additives for various types of fibres. When it introduced Scona TPPP 9212 in 2015, a coupling agent with a high level (1.8%) of chemi- cally bonded maleic anhydride, it was aiming it at polypropylene compounds reinforced with glass fibres, noting that the MA groups react with the amino groups of the silane of the glass fibre size. At JEC World in May this year, it was also highlighting the suitability of the product for improving the mechanical properties in polypropylene carbon fibre compounds. “E modulus, tensile strength and heat deflection temperature can all be consider- ably improved,” it says. BYK was also touting Scona TSPP 10213 GB, an adhesion promoter developed to improve the mechanical properties of PP compounds contain- ing glass, carbon and natural fibres, as well as fillers. It contains 2.1% MA. The company says its high flow makes the product especially suitable for composites with high fibre contents.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.southernresearch.org �
www.cytec.com (Solvay) �
www.westernresearch.org �
www.ornl.gov �
www.rmxtechnologies.net �
www.4mio.com �
www.calitzler.com �
www.zoltek.com �
www.procotex.com �
www.agy.com �
www.jm.com (Johns Manville) �
www.owenscorning.com �
www.michelman.com �
www.byk.com
www.compoundingworld.com
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