Question

The following figure describes the cooling process of polyethylene (PE). Determine whether the following statements are true or false. Liquid Rubbery State Specific Volume Glassy State Temperature Tg Tg (a) The cooling rate of 2 is faster than the cooling rate of 1. True ()? or False ()? (b) The solid PE created by the process 1 has a higher density than the solid PE created by 2. True ()? or False ? (c) The solid PE created by the process 1 is likely to contain more crystalline-like structures than the solid PE created by the process 2 True ()? or False ()? (d) The process 1 may be describing the solidification process for HDPE while the process 2 is describing the solidification process for LDPE. True ()? or False ( )? (e) The solid PE created by the process 2 is mechanically stronger than the solid PE created by the process 1. True ()? or False ()? (f) The glass transition temperature of this polymer will be increased when the polymer chains are cross-linked. True ()? or False ()? (g) HDPE is likely to be more viscous as liquid when compared to LDPE because of the larger van der Waals forces induced by a bigger amount of crystallinity. True ()? or False ( )? (h) Adding plasticizers will increase the glass transition temperature for this polymer. True ( )? or False ( )?

Answer 1

& liguid fast cooling slow cooling Slower cooling Tg, Tg2 T o is from above diagram cooling rate faster than cooling rate 2 . AAS false If it cools slowly, it get time to relax, transition occurs at lower temperature, change in temperature is slow, solid form at slow cooling is more denger than solid form at fast cooling 3. Solid PE created by ® has high density than solid Pe created by 0 CFast cooling " Ans false

c) solid PE formed by slow Cooling will tend to be crystalline and solid PE formed by fast cooling will tend to be amorphous in nature Solid PE by process € is more crystaline than solid PE created by process ☺ ie fast cooling . Ans false d) High Density polyethylene require High Density solid, which is form at slow cooling se proces © tow Density polyethylene require low Density solid, which is form at fast cooling le process o Process describe solidifation process of LDPE & ě process b describe solidification process of HOPE Ans: False

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