In today’s modern era of science and technology plastics have become one of the most widely used products all over the globe. Plastic is an organic substance and it consists of natural or synthetic binders or resins with or without moulding compounds. In general plastics are compounds of carbon with other elements such as hydrogen, nitrogen and oxygen. The materials designated as rubber, fibers, resins and plastics are of a similar molecular structure, and by appropriate chemical and physical treatment it is possible to interconvert any one of them. In architecture plastics were first looked upon as synthetic building materials which would give answers to all difficulties encountered in using existing materials.
Classification of plastics
Behavior with respect to heating
structure
Physical and chemical properties
Thermo plastic
Thermo setting
Rigid plastic
Semirigid plastic
Soft Elastomers plastic
homogenous
hetrogenous
Ts they are converted to a cured or infusible form through application of heat and cannot be remelted again. Tpsoftened when heated and regain original state upon cooling. They are soluble in wide range of organic solvents and cannot be used under high temperatures. Rphigh moe , retains shape under exterior stresses Srpmedium moe, elongates under pressure, normal when pressure removed Sp low moe, elongates under pressure, slowly normal when pressure removed Elastomerssoft with low moe, deform under load at room temp,return when load removed Homoonly carbon compounds Heterocontains c,o2,n Resins or binders Tp and ts Tpralkyd, cellulose, cumarone-indene, methyl methacrylate, styrene, vinyl Tsrcasein, melamine-formaldehyde, phenol formaldehyde, phenol furfuraldehyde, urea formaldehyde