UNIT-V MANUFACTURING OF PLASTICS In general many organic materials are used in Engineering Industries. Organic material is matter (stuff) that has come from a once-living organism(creature); is capable of decay.matterorganism How Organic Matter is created All living and growing matter on this planet contains organic components. Different types of matter include humans, animals, plants, and microorganisms. After the living matter dies, it decomposes.humansmicroorganisms Eg: ( Compostable Material, Food Waste)

Organic materials are classified into two types: Natural organic materials ( Coal, wood, petroleum and natural rubber) Synthetic organic materials (plastics, ceramics glass and synthetic rubber) These are called polymers (polymer is something made of many units. The units or “monomers” are small molecules that usually contain ten or less atoms in a row.)

POLYMERS Polymers are long chain molecules formed by polymerization process. – Linked polymers – Branched polymers – Cross-linked polymers – Network polymers

POLYMERIZATION PROCESS – The combination of many small molecules to form large molecules. It is achieved by 1.Addition polymerization 2. Condensation polymerization An addition polymer is a polymer which is formed by an addition reaction, where many monomers bond together via rearrangement of bonds without the loss of any atom or molecule. addition reactionmonomers Two or more unlike monomers are linked and there is a repetitive releasing small molecules as by-products such as water or methanol. This by - product formation is known as condensation.methanol

TYPES OF PLASTICS Thermoplastics and Thermosetting polymers. Thermoplasticsermosetting polymers Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be moulded again and again. Examples are polyethylene, polypropylene, polystyrene, polyvinyl chloride and polytetrafluoroethylene (PTFE).polyethylenepolypropylene polystyrenepolyvinyl chloride polytetrafluoroethylene Thermosets can melt and take shape once; after they have solidified, they stay solid.

MOULDING OF THERMOPLASTICS Injection moulding Blow moulding Rotational moulding Film blowing Sheet forming process PROCESSING OF THERMOSETS Compression moulding Transfer moulding

INJECTION MOULDING

Torpedo Band Heaters Shooting Pot Nozzle Hopper Plunger Screw meters plastic, plunger provides pressure Band Heaters Shooting Pot Nozzle Hopper Reciprocating Screw

TRANSFER MOULDING Transfer Molding (Resin Transfer Molding) is a process in which a pre-weighed amount of a polymer is preheated in a separate chamber (transfer pot) and then forced into a preheated mold through a sprue, taking a shape of the mold cavity and performing curing due to heat and pressure applied to the material.polymer Typical parts: Electrical and electronic components, rubber and silicone parts.

COMPRESSION MOLDING Compression Molding is a process in which a molding polymer is squeezed into a preheated mold taking a shape of the mold cavity and performing curing due to heat and pressure applied to the material.polymer Examples: Dishes, Handles, Electrical Components, Fittings and housings

BLOW MOLDING Blow Molding is a process in which a heated hollow thermoplastic tube ( parison ) is inflated into a closed mold conforming the shape of the mold cavity. thermoplastic There are three principal techniques of Blow Molding, differing in the method by which parisons are prepared: Extrusion Blow Molding Extrusion Blow Molding Injection Blow Molding Injection Blow Molding Stretch Blow Molding Stretch Blow Molding

ROTATIONAL MOLDING TYPICAL PARTS : Tanks, trash cans, boat hulls, buckets, housings, toys, carrying cases, and footballs.

EXTRUSION Extrusion process Most common manufacturing of plastic resin. Combines pigments, additives and resin. High heat, high pressure  molten mixture. Pushed through die. Create warm plastic for possible further “finishing” operation such as pelletizing, calendaring, or molding.

CALENDARING

THERMOFORMING