Automotive applications impact resistance

Polycarbonate properties that contribute to automotive applications include resistance to brittle fracture, clarity and optical precision, dimensional stabihty, impact strength, scratch resistance, and temperature resistance. 

Rubber-modified styrene-acrylonitrile copolymers (ABS) This material has a continuous SAN phase with about 15 wt.% rubber modification, generally polybutadiene. In most applications, impact resistance is the reason for the selection of ABS. Applications include housings and covers for appliances and tools, plus a variety of automotive moldings. 

The use of ABS has in recent years met considerable competition on two fronts, particularly in automotive applications. For lower cost applications, where demands of finish and heat resistance are not too severe, blends of polypropylene and ethylene-propylene rubbers have found application (see Chapters 11 and 31). On the other hand, where enhanced heat resistance and surface hardness are required in conjunction with excellent impact properties, polycarbonate-ABS alloys (see Section 20.8) have found many applications. These materials have also replaced ABS in a number of electrical fittings and housings for business and domestic applications. Where improved heat distortion temperature and good electrical insulation properties (including tracking resistance) are important, then ABS may be replaced by poly(butylene terephthalate). 

Polycarbonate is an extremely versatile polymer with a wide range of applications. Its stiffness, high heat distortion temperature, impact resistance, and clarity make it a favorite choice for durable goods tvith demanding application requirements. Its high modulus allows it to be used in many automotive, medical and domestic applications. 

Glass-filled, toughened polyethylene terephthalate) (PET) resins can be readily moulded into highly impact-resistant structural parts for appliances and automotive components. The PET-based compounds are also suitable for construction (e.g. as structural members), equipment housings (e.g. printer and copier parts), agricultural applications (e.g. mower and tractor engine covers), materials handling (e.g. pallets and trays), furniture (e.g. office chair bases), as well as electrical and electronic applications. 

When thermoplastics are reinforced with short fibres, both stiffness and strength may be increased, but these improvements are accompanied by a reduction of the ultimate strain for high concentrations of fibres [1-5]. This brittle behaviour is incompatible with growing engineering applications in which tlie parts are subjected to cyclic loadings or impacts, as in automotive under-the-hood applications. Thus, very tough nylon thermoplastics with enhanced creep and impact resistances have been produced by the introduction of a rubbery phase to the... 

The most important commercial blends of BPA-PC are poly(acrylonitrile-butadiene-styrene) (PC/ABS) and polybutylene terephthalate (PC/PBT) or polyethylene terephthalate (PET). Commercial grades of PC/ABS include CYCOLOY (GE), Bayblend (Bayer), and PULSE (Dow). PC/ABS blends exhibit improved flow and processability and enhanced low-temperature impact strength in comparison to PC (Fig. 3). These blends are widely used in applications requiring enhanced impact resistance, such as interior automotive parts and computer and electronics applications such as computer housings and cell phones. Non-halogenated flame-retardant PC/ABS blends are widely available. Poly(acrylic-styrene-acrylonitrile) (PC/ ASA) blends (GELOY , GE Luran , BASF) provide improved weatherability for outdoor applications such as exterior automotive parts, but exhibit reduced impact performance at low temperatures in comparison to PC/ABS. PC/PBT or PET blends (XENOY , GE Makroblend , Bayer) provide enhanced chemical resistance and weatherability for applications such as lawn and garden equipment and automotive bumpers and fasdas. 

The impact resistance of polypropylene at low temperature has been improved by polyblending with EPDM or E-P rubber to make possible the application of this material in the automotive industry. The low-temperature properties of polyamides such as nylon 6 and nylon 66 have been improved by polyblending with ethylene copolymers or specially grafted polybutadiene (45). 

Blends of PPE and PA-66 are suited for exterior automotive applications, where they produce class A surface on body panels, because they combine the processing and solvent resistance of polyamides with the moisture resistance and dimensional stability of PPE. Therefore, they have good heat resistance, impact resistance, moldabUity, paint adhesion and chemical resistance. 

Alloys made by combining polyarylamide with PA and polypropylene (which could be hghtly glass reinforced) offer low water absorption, even at high PP levels, good impact resistance, and lower density, which reduces price per volume. Targeted applications include automotive body panels, and electrical components. 

Typical automotive applications include gas cap covers, fan blades, shrouds for cooling systems, gears, fasteners, clips, emission control canisters, oil pans, shields, etc. Toughened polyamides are also used in sports and recreational equipment, lawn and power tool housings and components where impact strength, heat and chemical resistance are the primary criteria for their choice. With an estimated consumption of 25 Mton/y in the USA, impact modified PAs... 

Acrylonitrile-Butadiene-Styrene (ABS) Terpolymer. The acrylonitrile and styrene copolymer is grafted onto polybutadiene. The properties of SAN are combined with a greatly improved impact resistance and heat distortion resistance. ABS terpolymers And application as engineering plastics, in household appliances, luggage, telephone housings, automotive parts, and many more. 

Even though tire use is small, automotive applications are still the largest market for ethylene-propylene elastomers. They are used predominantly in radiator and heater hoses, seals, gaskets, grommets, and weather stripping. Blends of polypropylene and EPDM are used as material in the manufacture of car bumpers, fender extensions, and rub strips. Other applications of ethylene-propylene elastomers include appliance parts, wire and cable insulation, and modification of polyolefins for improved impact and stress resistance. 

ISO 11343, 1993, Adhesives—Determination of dynamic resistance to cleavage of high strength adhesive bonds under impact conditions- Wedge impact method The method is mainly aimed for the characterisation of metal substrates suitable for automotive applications. An instrumented impact testing machine (pendulum type) of 50-300 J and. 3-5.5ms maximum capacity is required for this test. A blunt wedge of approximately 1 mm tip radius and included angle of 8 is impact driven into a bonded joint at 3 ms" for aluminum alloy adherends and 2 ms" for steel adherends. The impact event should be... 

Thermoplastic matrices, is particularly attractive for automotive applications PP, for example, is economical, it can be processed quickly and can provide much better mechanical properties such as impact resistance, (i.e., bumpers, body panels [11]). PA are successfully applied in both under hood (i.e., inlet manifolds, radiator fans) and interiors (instrument panels, doors, front-end structures). For better temperature performance and mechanical properties, in some special application areas (motor racing sector, gearbox parts), polyether ether ketone and polyphenylene sulfide ( high performance thermoplastics ) are also used as matrices. 

Super-tough poly(sulfone)s can be produced by blending PES with acrylate rubber and a polycarbonate as an impact modifier. From this high impact strength composition, films and molded articles are useful in automotive applications, durable goods and appliances, medical and plumbing applications where resistance to hot, humid environments may be particularly important, and safety equipment and protective gear. 

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