1a)Thermoset plastics are similarto ferrous metals by way of strengthening as it is heated. However, they cannotbe remolded after initial heat-forming.
The polymer structure is highly linkedand are joined together by chemical bonds. A downside of that is poor elasticity.Examples of thermoset applications are below:· Plastic kitchen utensils · Tool handles· Keyboard buttons· Coating materialsThermosets are used were properties suchas stiffness, hardness, strength and electric insulation are required.1b)Thermoplastic materials melt whenthey are heated and are soluble in certain solvents. Different approaches canbe taken in developing thermoplastics which will lead to different properties.They can be developed to be either weaker and elastic by having a high concentrationof polymers with amorphous structures, or strong and rigid with a highconcentration of polymers with a crystalline structure.
Thermosets are used asthe following applications:· Insulation for electricalcables· Ropes· Belts· PVC piping1c)Elastomer is the scientificword for rubber. It has viscoelasticity making it both viscous and elastic. Thepolymer structure is only slightly crosslinked. They are flexible and elastic.Elastomeric materials have properties which make them either ThermosetElastomers that do not melt, or Thermoplastic Elastomers which melt whenheated. Applications for elastomers areas follows:· Diving wet suits · Car tires· Pencil erasers · Shoe outsoles 2) Moldingprocesses are simple, efficient, and versatile. Here are details and advantagesfor its use: a.
Enhanced StrengthWhile molding, it is possible toutilize fillers to add properties of strength to the final part. In plasticinjection molding, it is possible to use fillers in the injection molds. b. High EfficiencyOnce the molds and presses havebeen designed and programmed to spec, the actual molding process happens veryquickly. This allows many parts to be manufactured in quick succession from asingle mold. The high production rate makes molding cost effective andefficient.
c. Automation reduces labor andmanufacturing costThe injection moldingprocess is performed by machines and robots where a single operator can controland manage the proceedings. Using automation significantly reduces overhead whichin effect reduces manufacturing costs. Additionally, with reduced labor force,the overall cost of manufacturing the parts is reduced.
This cost savings canbe translated to a reduction for the customer as well. Molding is also cheaperthan plastic machining in the long run. Furthermore, Computer aided design(CAD) and computer aided manufacturing (CAM) allow minute tolerances during themaking of the molds.
d. Complex GeometryInjection molds are subjected toextremely high pressure. This results in the plastic within the mold to bepressed harder against the mold. Because of this excessively high pressure, itis possible to add a large amount of detail into the design of the part. Thisalso allows for complex and intricate shapes to be designed and manufacturedwhich otherwise would have been too complicated and expensive to manufacture.
To conclude, the molding processand particularly injection molding, reduce and sometimes eliminate the need forfurther working of the part post molding. This is due to the part being ejectedfrom the mold with a finished appearance. In this way, it ensures the partsmanufactured hardly require any work after the production.