Natural Rubber Natural rubber is an excellent example of a natural polymer and an elastomer in particular. Elastomers are substances that can be readily stretched. They retract rapidly to their original form when released. It undergoes long range reversible extension under relatively small applied force. This elasticity makes it valuable for variety of uses. Natural rubber is also called plantati...

Polyesters Polymers with ester linkage are called polyesters. Terylene or Dacron Terylene or Dacron is manufactured from ethylene glycol and terephthalic acid. The reaction is carried out at 420 - 460 K in the presence of catalyst zinc acetate and antimony trioxide. Properties Terylene forms strong fibers. It is crease resistant, has high moisture absorption and has a high tensile strength....

Rocket Propellants Propellants are the fuels used in rockets for propulsion. For example, alcohol, liquid hydrogen, liquid ammonia, kerosene, hydrazine and paraffin can be used as propellants. To burn them, rocket fuels require an oxidising agent. Examples are: liquid oxygen, liquid fluorine, dinitrogen tetroxide (N2O4), nitric acid (HNO3), a nitrate, chlorate or perchlorate. There are two type...

Dry cleaning is any cleaning process for clothing and textiles using an organic solvent rather than water. The solvent used is typically tetrachloroethylene (perchloroethylene), abbreviated "perc" in the industry and "dry-cleaning fluid" by the public. Dry cleaning is necessary for cleaning items which would otherwise be damaged by water and soap or detergent. It may be used ifhand washingneeded...

Chemotherapy Chemotherapy is the use of chemicals or drugs to selectively destroy infectious micro-organisms without destroying the live tissues or the host. Paul Ehrlich called drugs as magic bullets and the first milestone of his research was the discovery ofSalvarsan for curing syphilis, in 1909. In 1935, Gerhard Domagk, administered a dose of a dye called prontosil (inhibits the growth of str...