共聚酯薄膜单轴拉伸中的折射率椭球在线测量

On-line measurement of refractive index ellipsoids in uniaxial stretching of co-polyester films

聚酯膜的光学性能取决于其化学组成以及在特定工艺条件下形成的结晶、取向结构,拉伸过程中聚酯结晶、取向结构演化的相关研究,对高品质聚酯光学膜的生产具有重要意义。将一束强度随时间交变的激光源分为参考光、直射测量光、斜射测量光三路,利用测量光通过介质时的光学延迟能够通过测量光和参考光的强度-时间曲线的相位差来反映的原理,组建可在线测量介质折射率椭球变化的装置,在此基础上,对改性共聚酯膜单轴拉伸过程中的应力-光学行为进行研究,考察分子链刚性对聚酯分子应力诱导取向效应的影响。结果显示,分子刚性较大的共聚酯对单轴拉伸载荷的响应更为敏感,能够更快地在拉伸方向形成较高的取向,但分子刚性较大的共聚酯垂直于载荷方向的取向调整能力变弱。

The optical properties of polyester films depend on their chemical composition and the crystalline/oriented structures formed under specific process conditions.Studies related to the evolution of polyester high sub-structures during the stretching process are of great significance for the production of high-quality polyester optical films.A laser source with alternating intensity over time is divided into three channels,namely,reference light,direct measurement light and oblique measurement light.Then a device for on-line measurement of refractive index ellipsoid change of the medium is set up by the principle that the optical delay of measurement light through the medium can be reflected by the phase difference between the intensity-time curves of measurement light and reference light.The stress-optical behavior of modified polyester films during uniaxial stretching was investigated using the device,and the influence of molecular chain rigidity on the stress-induced orientation effect of polyester molecules was examined.The results show that co-polyesters with greater molecular rigidity are more sensitive to the response to uniaxial stretching load and can form higher orientation in the stretching direction more quickly,but the orientation adjustment ability perpendicular to the load direction becomes weaker for co-polyesters with greater molecular rigidity.