Plastic

Published on February 2017 | Categories: Documents | Downloads: 67 | Comments: 0 | Views: 744
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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. Tpsoftened when heated and regain original state upon cooling. They are soluble in wide range of organic solvents and cannot be used under high temperatures. Rphigh moe , retains shape under exterior stresses Srpmedium moe, elongates under pressure, normal when pressure removed Sp low moe, elongates under pressure, slowly normal when pressure removed Elastomerssoft with low moe, deform under load at room temp,return when load removed Homoonly carbon compounds Heterocontains c,o2,n Resins or binders Tp and ts Tpralkyd, cellulose, cumarone-indene, methyl methacrylate, styrene, vinyl Tsrcasein, melamine-formaldehyde, phenol formaldehyde, phenol furfuraldehyde, urea formaldehyde

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