有机玻璃“全去偶极子极化”现象研究

Study on phenomena of "whole dipole-depolarization" of PMMA

实验中观察到用作塑料光纤纤芯材料的纯有机玻璃(聚甲基丙烯酸甲酯)在加速热老化和紫外老化过程中其相对电容率急剧下降至大约等于其折射率的平方,即有机玻璃由极性聚合物变为非极性聚合物(“全去偶极子极化”现象)。对此现象的解释机理提出了“孔洞”与“极性基团断裂”两种假设。通过其他实验(如红外光谱、测量密度、测量折射率、测量体积电阻率)的相互对比,基本上肯定了有机玻璃“极性基团断裂”的热老化模型。

During the accelerated thermal aging and ultraviolet radiation aging of PMMA which is used as the core materials of fiber in POF, it was found that the relative permittivity of PMMA decreased significantly to approximately equal to its square refractive index. That means PMMA has changed from polar polymer to non-polar polymer. In order to explain the phenmena, two supposes of ＂hole＂ and ＂polar-group rupture＂ are proposed.according to the tests of IR, density, refractive index, conductor volume resistivity, the aging model of PMMA is confirmed likely.