| Abstract: | Removal of the ultrahigh molecular weight fraction in high-density polyethylene by hydrodynamic crystallization and analysis of the subsequent drawing behavior leads to the conclusion that the small portion of extremely long chains present in polymers with a log-normal molecular weight distribution is not necessary for the achievement of high draw ratios, that is, in excess of 30×. Furthermore, a certain minimum weight, and therefore chain length, is required for the attainment of high draw ratios. For example, paraffins with a molecular weight of 23,000 draw only up to about 5×. A logical extension of these concepts to other polymer systems is presented. |
