超高分子量聚乙烯的红外光谱的特性研究

研究了超高分子量聚乙烯(M_w>1×10⁵)的红外光谱-温度特性.3条非晶谱带(1368、1352和1304cm^-1)的吸收强度均随温度升高而增大,但都比普通分子量聚乙烯增加的小,尤以高于140℃更甚.分子链中次甲基的近程构象序列分布随温度的变化不受分子量的影响,但旁式构象序列分布则随温度升高而增大.升温和降温过程的红外光谱均表明1352和1304cm^-1两谱带随结晶状态的变化比1368cm^-1更敏感.

Studies on the Infrared Spectral Behavior of Ultra-high Molecular Weight Polyethylene

The change of infrared spectral behavior of ultra-high molecular weight polyethylene (M_w>10×10⁵) with temperature was studied.It was found that the absorption strengthes of three bands (1368, 1352.and 1304 cm^-1) arised from amorphous regions were increased with increasing temperature, but the increasements were less than those of the conventional molecular weight polyethylene (M_w= 10×10⁴), especially in the case of temperature range higher than 140℃.The change of short-range conformation distributions of methylenes in molecules with temperature was independent of molecular weight while the gauche conformation distribution of methylenes was increased with the increase of temperature.Both the spectral results obtained in heating and cooling processes showed that the bands of 1352 and 1304 cm^-1 were more sensitive to the change of the state of the crystalline phase than the band of 1368 cm^-1.