A MOLECULAR MECHANICS INVESTIGATION INTO THE MECHANISM OF THE LOW-TEMPERATURE RELAXATIONS OF 3 POLY(ALKYL METHACRYLATES)

被引：10

作者：

BAAS, JMA ^{[1
]}

VANDEGRAAF, B ^{[1
]}

HEIJBOER, J ^{[1
]}

机构：

[1] TNO,CTR POLYMER MAT,2628 VK DELFT,NETHERLANDS

来源：

POLYMER | 1991年 / 32卷 / 12期

关键词：

MOLECULAR MECHANICS; POLY(ETHYL METHACRYLATE); POLY(ISOPROPYL METHACRYLATE); POLY(CYCLOHEXYL METHACRYLATE); CONFORMATIONAL ANALYSIS; MECHANICAL LOSS; BARRIERS TO ROTATION; SIDE GROUP MOTIONS;

D O I：

10.1016/0032-3861(91)90037-J

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

The enthalpy curves for the rotation of the ester groups around the O-alkyl bonds in three-unit all-anti models of syndiotactic poly(ethyl methacrylate), poly(isopropyl methacrylate) and poly(cyclohexyl methacrylate) have been calculated using molecular mechanics. The abundance of conformers and the enthalpies of activation for their interconversion at 50 K have been related to the mechanical loss processes at low temperature with Hoffman's theory for a three site model with two equienergetic sites. The calculated activation energies compare well with the experimental values of the delta-relaxations. The mechanical loss process is in all cases caused by the exchange of ester side chain positions by partial rotation around the O-alkyl bond.

引用

页码：2141 / 2145

页数：5

共 16 条

[1]

ALLINGER NL, 1981, QUANT CHEM PROGRAM E, V13, P395

[2]

BURKERT U, 1982, MOL MECHANICS, P224

[3] RELAXATION PROCESSES IN THE GLASSY STATE - MOLECULAR ASPECTS [J].