ABS
The structure of ABS is based on 3
monomers - acrylonitrile, butadiene and styrene. It is therefore
defined as a terpolymer. Its manufacture is
essentially based on the graft polymerisation of
polybutadiene latex (the rubbery phase) with
styrene acrylonitrile polymer (SAN the plastic
phase). Varying the proportions of the three
monomers, and the way in which they are combined,
means that a wide spectrum of ABS plastics can be
produced, with properties 'tailored' to meet
specific requirements.
In addition to this great versatility, ABS
plastics in general are distinguished by great
toughness and high impact strength (even at low
temperatures), good dielectric properties and
excellent dimensional stability. To this is added
extremely fine gloss appearance, very wide
colouring possibilities and ready availability.
All these attributes mean that when ABS was
introduced in the mid 1950s, plastics could for
the first time offer real competition with many
traditional materials such as metals, for making
highly durable mouldings with great consumer
appeal.
ABS was in fact the first 'engineering'
thermoplastic and major outlets were soon found
in the automotive industry, furniture (the
Kartell one-piece chair) and especially in a huge
variety of electrical and electronic appliances,
from telephones to typewriters, calculators, adio-visual
units and kitchen equipment.
Thermoforming extruded ABS sheet led to some
spectacular uses, notably the body of the Citröen
Méhari jeep-like car. Almost 145,000 were built
between 1968 and 1987, easily a record for a
plastics-bodied car. Not all applications were so
massive: the first important European application
was the famous Lego brick from Denmark.
Although now augmented by other engineering
thermoplastics with more specific properties, (e.g.
acetals, polycarbonates, thermoplastics
polyesters, polyphenylene oxide, etc.) ABS
remains a very important - and versatile! -
plastics material.
|