| 摘要 |
<p>An ethylene polymer comprises 50-97 mole % ethylene units, 3-50 mole % 3-18C 1-alkene units and optionally other comonomer units. The polymer has density at most 910 Kg/cu.m., at least two melting points, one between -80 deg. C and (120-3x) deg. C but not above 100 deg. C and another between (120-3x) and 140 deg. C and at least two crystallisation points, one between -90 deg. C and (110-3x) deg. C but not above 90 deg. C and another between (110-3x) and 130 deg. C, where x is the total mole % of comonomers. The deviation Wc in enthalpy, defined by the formula (I), where ha and hc are the theoretical values of the specific enthalpies of 100% amorphous and 100% crystalline polypropylene resp. and h is the specific enthalpy of the polymer, is at least 1% at (120-3x) deg. C and at 23 deg. C is at most 0.87 of the Wc at -70 deg. C.</p> |
