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Limitations: Cost, Anisotropic, High processing temperatures
Application: Pump rotors, bushings and gears, aircraft Interior parts, pump
manifold, cable conduits, ventilation wheels, automotive under hood parts,
Transmission Thrust Washers, electronics, flexible PCB, deep water application
parts, medical devices, endoscopes, dental and other term implants.
50) Cellulose acetate (CA):
Is a natural plastic, which is manufactured from purified natural cellulose - is derived
primarily from two sources, cotton linters and wood pulp. Natural cellulose is
reacted with acetic anhydride to produce Cellulose Acetate, outcome is flakes
which are then ground to a fine powder. CA in powder form can only be processed
by dissolving in a solvent and spinning or casting. However it to be processed by
normal plastics processing techniques is blended with a suitable combination of
plasticizers and additives and melt compounded to get Cellulose Acetate Granules.
Density 1.26 - 1.34 g/cm 3
Glass transition temperature 95 - 110 °C
Max/Min continuous Service temperature 45 - 80 °C / -30 °C
Melting Point Tm 138 - 175°C
Processing temperature: 175 to 250°C
Drying before processing is highly recommended: 2-3 hr. at 70°C.
Injection Moulding: mould temperature of 40-70°C is recommended. It is important
that cellulosic plastics be cooled slowly to minimize strains in the moulded article.
Extrusion: A L/D of around 30 is recommended.
CA is a high performance thermoplastic with high transparency, surface gloss and
aesthetic appeal, have high impact and mechanical strength, high dielectric
constant and excellent machineability. They are fairly resistant to chemicals, are
compatible with human skin and can be variedly coloured.
Strength: high transparency (transmitting >90% light), excellent colourability, good
scratch resistance and dimensional stability, no problem of dust accumulation due
to weak electrostaticity.
Limitations: Poor weather resistance, Sensivity to moisture, poor chemical
resistance (attacked by alcohols, ketones and concentrated acids), mechanical
properties highly differ with plasticizer level, poor heat resistance.
Applications: Ophthalmic sheets, Tool Handles, candy wrappers, apparels
buttons, sunglasses, Pressure sensitive tape, sealants.
51) Cellulose acetate butyrate (CAB):
Is little more expensive than the cellulose acetate, is somewhat tougher, is resistant
to ultraviolet rays and has lower moisture absorption. It has relatively good
weatherability and excellent transparency.
Density 1.16 - 1.31 g/cm 3
Glass transition temperature 98 - 107 °C
Melting Point Tm 188 - 235°C
Butyrate, as it is commonly known, is a cellulose ester modified by using butyric and
acetic acids producing CAB. Unlike other common, the cellulosic plastics are not
polymerized; instead, they are produced by the chemical modification of cellulose, a

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