Question

Please answer the polymers questions below clearly.

10. Explain why poly(n-butyl acrylate) (below left) has a lower than poly(methyl methacrylate) (below right). tan 0 - 0 --CH, 11. You are using flexible PVC tubing in your laboratory to run water from the tap to keep your reaction vessel cool. One day, your idiot of a lab partner runs an organic solvent through this tubing. It becomes stiff and cracks. Explain why. 12. Explain why the crystallite size of a poly- mer varies with the degree of undercooling.

Answer 1

1.Butyl acrylate is the principle acrylic ester monomer polymerized with methyl methacrylate, styrene, and vinyl acetate monomer to obtain the requisite degrees of hardness, flexibility and toughness in a copolymer system. MMA (Tg 105°C) and styrene (Tg 100°C) increase hardness and cohesive strength and reduce tack. In the copolymer composition, BA (Tg -45°C) increases flexibility, toughness, elongation, tack, and low-temperature properties. Increasing the BA content will also reduce the minimum film forming temperature to below room temperature.thats why it has lowe Tg.

2.As PVC is water resistant it runs water without any effect because it contains chlorine,but organic solvent dissolves PVC or swelled that tubing due to that it removes polymer chain of tubing and after a time it stiffs and crack down.

3.Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid.

  As temperature decreases, the corresponding increase in chain orientation at a given shear rate leads to an absolutely faster crystallization. At the same time, however, a temperature decrease makes the flow-induced driving force to crystallization relatively less influent with respect to the intrinsic kinetics.and it's directly affect to the size of polymer.