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在30～130℃温度范围内测量了聚苯乙烯(PS)样品中的正电子素湮没寿命,据此计算了样品中自由体积的大小和自由体积分数,发现在不同的温度范围,它们随温度变化的斜率不同,由此确定了PS的玻璃化转变温度为80℃.同时,还研究了不同压强对PS的自由体积的大小、浓度及分布的影响.实验结果发现,压强从6MPa增大到20MPa时自由体积分布变窄.同时,当压强超过100MPa,o-Ps寿命分布由单峰变成双峰.这说明高的外力场作用下,样品中分子链构型发生变化,导致分子链堆积密度增加及局部有序区域的形成.
The positron annihilation lifetime in polystyrene (PS) samples was measured at a temperature in the range of 30-130 ° C. From this, the free volume fraction and free volume fraction in the sample were calculated and found to vary with temperature The results show that the glass transition temperature of PS is 80 ℃ .At the same time, the influence of different pressure on the size, concentration and distribution of free volume of PS is also studied.The experimental results show that the pressure increases from 6MPa to 20MPa, the free volume distribution becomes narrower.At the same time, when the pressure exceeds 100MPa, the life distribution of o-Ps changes from unimodal to bimodal.This shows that under the action of high external force field, the molecular chain configuration changes in the sample, leading to the accumulation of molecular chains Increased density and the formation of locally ordered regions.