Question

Three samples of flexible tubing are subjected to the following tests:

(a) Held in burner flame. Tubes A and C burn.

(b) Soaked overnight in chloroform. Tube A swells, B becomes very stiff and

somewhat smaller on drying out, and C is unaffected.

(c) Immersed in a lead nitrate solution, A turns black; B and C are unaffected.

Which of the three is vulcanized rubber, polyethylene, or plasticized PVC?

Answer 1

A. Vulcanized rubber: It will burn in burner flame, swells in chloroform and turn lead nitrate black when immersed in lead nitrate solution. This happens because it has sulphur in vulzanized form.

B. Plasticized Poly(vinyl chloride): It will not burn and on soaking with chloroform extraction procedure will take place and plasticizer will be disscolved leaving away unplasticized poly(vinyl chloride) which will be stiff and somewhat smaller on drying out.

C. Poly(ethylene) will burn but not get affected by soaking in chloroform solution and immersing in lead nitrate solution.