Dielectric material: plastics, Physics

Plastics are polymers, meaning they are made up of molecules from many different elements. By utilizing different combinations, new polymers are made that can be manipulated from many different things. Plastics are organic materials of higher molecular weight and are capable of being formed into a desired shape during or after their manufacture. However, organic materials may to be the sole constituents of plastics. The term plastic is used very frequently in common terminology even for materials which are not really plastics if viewed from the definition given above. Resin is the substitute world normally used in insulation technology in place of plastic. Plastics are synthetic resins obtained basically in two different ways, by linear polymerization and by poly condensation. The recurring chemical reaction by which molecules weight composition is called "POLYMERIZATION", and the linear polymerization is a reaction is chemical in which high molecular compound is obtained from a lower molecular compound. Without evolution of a by product in linear polymerization several monomers are linked to one another and form a single polymer molecule. These molecules are relatively easy to recycle. The polymers achieved through linear polymerization are known as "Thermoplastics". Thermoplastics can be melted and reformed any number of times. Thus they are relatively easy to recycle. When the reacting molecules combine in such a way that there is evolution of a by product of the molecular weight, like water, the process is called 'Condensation Polymerization "and this irreversible chemical reaction between different low molecular compounds. There are two general types of the linear and the spatial condensation. Thermosetting plastics are melting on heating but are converted into a rigid solid mass if maintained at an elevated temperature long enough. They become unable to maintained melt after this and hence become insoluble in any solvent.

Spatial polymers are characterized by:

  1.    Insolubility and poor insulating properties
  2.    Hardness and brittleness
  3.    Not capable of fibre formation
  4.    Good mechanical properties
  5.    High Hygroscopicity

Linear polymers are characterized by:

  1.    Good solubility and good insulating properties
  2.    Flexibility and elasticity
  3.    Capability of fibre formation
  4.    Poor mechanical properties
  5.    Low Moisture content

Posted Date: 7/7/2012 6:05:15 AM | Location : United States







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