10-290K环境下聚酰亚胺纤维导热性能研究

Thermal conductivity of polyimide fibers at 10-290 K

为探究聚酰亚胺纤维的热导率随温度变化的规律及成因,利用瞬态电热技术得到聚酰亚胺纤维在不同温度下的热导率。实验研究表明,当温度处于10~290 K范围内,随着温度的降低,聚酰亚胺纤维的热扩散系数逐渐升高,热导率逐渐降低。从晶格振动(声子)导热为主入手,通过研究温度与晶格振动、声子浓度、声子平均自由程等实验参数之间的关系,在排除宏观方面例如气孔等材料瑕疵造成的影响后,得出结晶率是影响聚酰亚胺纤维在玻璃化转变温度附近热导率随温度变化的主要因素,而晶格振动是影响聚酰亚胺纤维在德拜温度附近热导率随温度变化的主要因素。因此可以通过改变结晶率、改善工艺条件等方法,制备满足不同生活、生产、科研需要的聚酰亚胺纤维。

In this experiment,the thermal conductivity of polyimide fibers at different temperatures is obtained by using transient electrothermal technology in order to explore the rule and cause of the variation of the thermal conductivity of polyimide fibers with temperature.The experimental results show that when the temperature is in the range of 10-290 K,with the decrease of temperature,the thermal diffusion coefficient of polyimide fiber increases gradually,and the thermal conductivity decreases gradually.In this paper,we start from the lattice vibration(phonon)thermal conductivity,and study the relationship between temperature and lattice vibration,phonon concentration,phonon mean free path and other experimental parameters.After excluding the influence of macroscopic defects such as pores,it is concluded that the crystallization rate is the main factor affecting the thermal conductivity of polyimide fibers near the glass transition temperature while the lattice vibration is the main factor affecting the thermal conductivity of polyimide fibers near the Debye temperature.Therefore,polyimide fibers can be prepared by changing the crystallization rate and improving process conditions to meet the needs of different life,production and scientific research.