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Shaping Processes of Polymer
ElastomersIt contains long chain molecules that are cross linked. They owe their impressive elastic properties to combination of two features:(i) Long molecule tightly kinked when unstretched(ii) Degree of cross‐linking is substantially below that of thermosets
Curing is required to effect cross –linking in the elastomers. The term curing is known as VULCANIZATION involving the formation of chemical cross‐linking of polymer chains .
Elastomers
• ViscosityViscosity is defined as resistance to fluid flowMeasure of internal friction
• ViscoelasticityCombination of viscosity and elasticityStrain gradually increases under applied stress and also decays gradually whenthe stress is removed
Properties of polymer melts
Elastomers
Natural Rubber ‐High molecular weight of ISOPRENE (C5H8)n‐ Sticky in hot weather‐Brittle in cold weather
VULCANIZATION leads to improvement of the property‐ High tensile strength‐Resilience‐Tear strength‐Resistance to wear and tear
Synthetic Rubber‐STYRENE –BUTADINE rubber : (C8H6)n(C4H6)m‐Predominant raw material is PETROLIUM
Extrusion
Normal Extrusion
Polymer Extrusion
Extruded Products
Extruded Product
Blown Film Extrusion
Polymer Fibre: Melt Spinning
Injection Moulding
Injection Moulding
Injection Moulding
Screw type
Plunger type
Compression Moulding
Compression Moulded Products
Blow Moulding
Stretch Blow Moulding
Rotational Blow Moulding
Rotational Blow Moulding
Rotational Blow Moulding
Mobile Phone Shells
Thermoforming
Thermoforming
Semiconductor, consumer electronics and electrical, data storage, telecommunications, and medical industries.
Polymer Sheet
Chill Rolling
Transfer Moulding
Polymer Foams
Polymer Foaming