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472 Plastics Engineering

TABLE VI Application of Plastics in the Automotive Industry
Application Properties sought Typical materials used
Bumpers, fenders, side protection bars Impact resistance, paintability (or Class A finish) Polypropylene, alloys of PC, PPE/PA alloys
Fascias Rigidity, good surface detail Polypropylene
Body panels Rigidity, energy absorption, Class A finish Reinforced PP or PET, SMC or alloys of PC/PBT
Wheel arches UV resistance, impact strength, abrasion resistance PP, HDPE
Electrical components, gears, etc. High modulus, dimensionally stable PPS, PBT, polyacetal, reinforced nylons
Fuel tanks Impact resistance, low permeability HDPE, multi layers
Seat foams, soft touch trim Lightweight, flexible, durable Polyurethane
Grills Stiff, dimensionally stable, easily molded ABS, polypropylene
Cable sheathing Electrical and thermal resistance, impermeable to water PVC and cross-linked PE
Fuel lines Low permeability, flexible, tough Nylons, multi layer materials
Transparent fittings Clarity, surface hardness, toughness Polycarbonate acrylic (PMMA)
Washer bottles Tough, inert to chemicals, impermeable HDPE, PP
Headlights Tough, good optical properties Polycarbonate
Intake manifolds Stiff, high temperature and oil/fuel resistance Nylons
Safety belts High strength, flexible, tear resistant Nylons

trays, and dental tools. Polyetheretherketone (PEEK) is limbs to be repaired or replaced by a synthetic material
sterilizable by autoclave, gas, or high-energy radiation that is accepted by the human body and encourages new
and offers good chemical resistance. Common uses in- tissue growth.
clude catheters, disposable surgical instruments, and ster- Plastic/fiber composites are also being used very ef-
ilization trays. Polyurethane can be sterilized using dry fectively to meet the tough weight and strength demands
heat, gas, or radiation, and its applications include tubing, made by artificial limbs. In this application lightness is
catheters,connectors/fittings,pacemakerleads,tensioning crucial because if, for example, a patient needs to have
ligatures, wound dressings, and transdermal drug-delivery a whole leg replaced, the prothesis acts like a pendulum
patches. Polycarbonate and its blends are capable of being and is difficult to control if it is too heavy. The success-
sterilized by all the common methods, and its uses include ful development of fiber composites in artificial limbs has
equipment housings and reservoirs. Liquid-crystal poly- meant that patients are able to adapt and use the new limb
mers (LCPs) can also be sterilized by all the common quickly and easily and without pain or discomfort.
methods and are used in products such as dental tools,
surgical instruments, and sterilizable trays.
D. Electrical Applications
Examples of life-saving devices based on the unique
properties of plastics are evident in every hospital ward The effects caused by static (electrostatic discharge, ESD)
andoperatingtheater.Sometypicalexamplesaretheuseof and electromagnetic/radiofrequency interference (EMI/
carbon-fiber-reinforced plastics in operating tables, NMR RFI) are familiar as sparks jumping from fingertips to
imagers, and radiotherapy simulators. In these applica- a doorknob or clothing and electronic noise in com-
tions the combination of lightness, strength, stiffness, and munications networks. In some cases these are just an
good fatigue resistance are supplemented by relatively low inconvenience (or can be used to advantage such as in
absorption of X-rays. This means that much clearer, packaging cling film), but when they are present in, on,
sharper images are obtained with lower dosages of ra- or near electronic circuitry or flammable environments,
diation. they create hazards that must be or eliminated. ESD can
In general, the drive to reduce healthcare costs and the damage or destroy electronic components, erase or al-
need to use disposable medical supplies are important ter magnetic data storage, and initiate explosions or fires.
factors generating a higher demand of medical plastics. Electromagnetic and radiofrequency waves radiate from
New materials, with improved properties, are being computer circuits, radio transmitters (including cellular
developed in order to satisfy the requirements of infection phones), fluorescent lamps, electric motors, lightning, and
control standards. Current research is being conducted to many other sources. In most cases they are harmless but
determine the biological reactivity of polymeric materials. they become undesirable when they interfere with other
Some new types of polymeric material can match very electrical equipment. An example of this is interference
closely the performance of bone. This enables broken with medical devices such as pacemakers.