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Acrylics modified by halogen-containing comonomers such as vinyl chloride or
vinylidene chloride are classified as modacrylics. Chlorine imparts a notable flame
resistance to the fibre, an advantage that makes modacrylics desirable for such
products as children's sleepwear, blankets and tents.
Acrylic fibres are also used as precursors for the production of carbon and graphite
fibres, as replacements for asbestos in cement, fiber reinforced concrete, hollow
fibers for reverse osmosis, hot gas filtration systems and in industrial filters and
battery separators.
Copolymers of acrylonitrile are also used as Plastics - Polystyrene-acrylonitrile
(SAN) and polyacrylonitrile-butadiene-styrene (ABS),
20) Acrylonitrile Butadiene Styrene (ABS) :
This material is a terpolymer of acrylonitrile, butadiene and styrene. The material
properties can be tailored to get specific desired properties: the acrylonitrile
component gives chemical resistance and heat stability, the butadiene gives
toughness and impact strength and the styrene gives rigidity and processablity.
Varying the A-B-S ratios will change the properties significantly and the number of
grades available is almost limitless.
The ABS material itself can also be 'alloyed' with other materials such as PC,
PMMA, PBT, PA, polysulfones and even PVC. This creates an even greater choice
of properties and processing opportunities. Additives enable ABS grades that are
flame retardant, transparent, high heat-resistance, foam-able or UV-stabilized.
Density 1.02 - 1.21 g/cm 3
Glass transition temperature 90 - 102 °C
Max / Min continuous Service temperature 86 - 89 °C / 60 - 80 °C
Melting Point 210 - 270°C
ABS can be processed by Injection, Blow, and Extrusion methods. ABS is ivory
naturally but wide colour range available.
Pre-drying is not always needed. Signs of moisture are stripes, streaks or bubbles in
the product for injection moulding. Pre-drying 4 hours at 80°C is generally sufficient.
Mould temperature of 40-70°C is recommended. For Extrusion L/D ratio of 25-30 is
recommended.
Strengths : High rigidity, outstanding impact resistance even at low temperatures,
easily processed good weldability, good abrasion and stain resistance, High
dimensional stability (low water absorption), easy to bond with adhesives, painted
and also electroplate, excellent resistance to sterilization (gamma radiation), good
machinability, easy to thermoform
Limitations : Poor weathering resistance, ordinary grades burn easily and non self
extinguishing, Poor solvent resistance, particularly aromatic, ketones and esters,
Hygroscopic - needs drying before processing, stress cracking in the presence of
some greases
Applications : Safety helmets, Dashboard components, Instrument panels, Seat
belt components, Rear light housings, electroplated in fascia panels, radiator
grilles, Consumer goods like Food containers, luggage shells, housings for vacuum
cleaners, food processors and hair driers, vacuum formed refrigerator door liners
and internal trays, telephone set, computer housings, machine housings, pipes and
fittings, Small boat hulls, Medicine boxes, Nebulisers and others.

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