materials | Automotive
Right: Photo of typical
prospective engine cover application for new Chemlon compounds
drop the driving range of vehicles. PolyOne is collabo- rating with carmakers interested in its Therma-Tech thermally conductive materials to help solve these battery-related challenges.
Fire fighting Another compounder noting the increasing importance of flame retardance in engine compartments is Teknor Apex Company. It says two new glass fibre-reinforced polyamide compounds exhibit outstanding flame retardance and exceptional thermal stability for UTH parts such as engine covers. Chemlon 904-13 GVNH and 204-13 GVNH compounds with low halogen content meet the UL-94 V-0 standard at a thickness of 0.8 mm. “Conventional halogenated compounds achieve this
degree of flame retardancy only with high levels of flame retardant and synergistic filler that make processing difficult, yield poor surfaces, and increase product density,” says the company. “In contrast, the new Chemlon compounds yield a smooth surface, are 15% less dense than conventional counterparts, and are readily processed for parts with long flow paths or thin walls.”
Equally valuable for under-hood applications is the
thermal stability of the new compounds, according to Jeff Schmidt, automotive industry manager for the Nylon Division of Teknor Apex. “Chemlon 904-13 GVNH is an especially high-temperature material, with a heat deflection temperature of 245°C and a high degree of property retention at elevated temperatures,” says Schmidt. “In fact, this compound provides a continuous use temperature that is much higher than specification.” Lead acid battery casings have for a long time been the primary application in automotive for UL FR rated products, says a representative for a third compounder, A. Schulman. Other applications include fuse boxes and convoluted tubing for wiring harnesses. “There is an increasing trend to utilize more UL rated materials though in other applications: rechargeable battery
Typical properties of new Chemlon grades from Teknor Apex 204-13 904-13
Compound Density, g/cm3 (ISO 1183/A)
Charpy notched impact strength at 23°C, kJ/m2 Charpy notched impact strength at -30°C, kJ/m2 Tensile stress at break, MPa (ISO 527) Elongation, % (ISO 527)
Flex modulus, MPa (ISO 178)
Heat deflection temperature (1.8 MPa), °C (ISO 75) Flammability @ 0.8 mm(UL94)
Flammability @ 0.8 mm after 3,000 hrs at 140°C (UL-94) 22 INJECTION WORLD | May/June 2017 (ISO 179) ( ISO 179)
GVNH GVNH 1.31 3.5 3.0 85
1.31 4.5 3.7
3.0
6,000 185 V-0 V-0
105 3.0
6,000 245 V-0 V-0
casings, battery trays, electronic junction boxes and heat shields,” the spokesperson says. “We would also expect that there will be a push to move away from halogenated FR materials to non-halogenated FR materials.”
Sensor solutions
Going hand in hand with the increasing electrification of cars is the rapid growth in the use of sensors. Cars being built today can have 100 or more sensors on board – many of them in and around the engine compartment – monitoring multiple vehicle functions and picking up external data. Before long, that number could double, according to one source. By 2020, annual production of automotive sensors could be over 20 billion. The performance requirements for these sensors are also growing. Protection is particularly important for sensors that are exposed to harsh environments and must stand up against chemicals such as road salt and other materials that can damage the sensors.
No surprise then that several plastics suppliers are upping their game on development of materials to encase these sensors. One of the latest examples comes from A. Schulman, which has just launched Schulamid 612 GF 33 H2, a tailored PA612 grade which is said to provide superior protective performance for automotive sensor housings. The new grade has much lower moisture absorption than lower molecular weight polyamides, improving dimensional and mechanical stability as well as reliability. “While conventional housing materials such as PA 66
show environmental stress cracking in contact with road salts like calcium chloride, A. Schulman’s new grade raises the chemical resistance of the housing and provides enhanced protection,” the company claims. It also offers a high-flow grade, Schulamid 612 GF 33 H2 SF, which enables lower injection pressures to be used,
www.injectionworld.com
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