摘要
本文用玻璃丝伸长法对Na_2O-Li_2O-P_2O_5玻璃熔体在10~9～10^(13)dPa·s粘度范围内的定向双折射现象及其弛豫时间进行了研究.研究表明该系统玻璃丝在外张力作用下伸长时显示出了极高的双折射效应.当P_2O_5含量由60mol%向47mol%变化时,出现了从牛顿到非牛顿流体性质的变化,使外张力对双折射弛豫时间也产生了不同的影响.在一定温度下,对应于一定外张力的双折射和粘度的平衡值,实际上是内部链状结构单元缠结与部分解结以及伴随的瞬变现象建立动平衡后定向的结果.在所测粘度范围内熔体的链状结构单元未发生变化.双折射弛豫时间系由缠结链团的变形定向过程(或反过程)τ_1和缠结团内链状结构单元的定向过程(或反过程)τ_2两部分所组成.
The orientational birefringence and the relaxation time of ternary sodium-lithium phosphate glass melts have been investigated in the viscosity range from 10~9 to 10^(13) dPa·s by using the fibre elongation method. The fibres under applied tension show very high birefringence and their flow behaviour changes from Newtoniar to non-Newtonian with the change in compositions from 60 mol% to47mol% P_2O_5, which has different influences upon the relaxation time of the birefringence under appliee tensile stress. The values of birefringence and viscosity in a certain temperaturn and corresponding tensile stress are considered as the result of orientation in dynami equilibrium for the entanglement and partly disentanglement in the chains with the bone switching process. In the viscosity range measured, the type of the chain structura unit in the glass melt has no change. The relaxation time of birefringence include two parts, τ_1 and τ_2, the one corresponding the orientation (or disorientation of the deformation of the tangled chains and the other the orientation (or disorien tation) of the chains in the tangle.
关键词
磷酸盐玻璃
熔体结构
双折射
orientation
birefringence
relaxation time
tangle
structure a glass melts
