摘要
聚对苯二甲酰对苯二胺(PPTA)能溶于浓硫酸(H_(2)SO_(4)),在一定的温度和浓度范围内呈现液晶相,可以经干喷湿法工艺纺丝制得对位芳纶。PPTA/H_(2)SO_(4)溶液的相行为和流变行为是决定对位芳纶加工工艺和性能的关键因素,但是缺乏便捷的研究工具。本研究为旋转流变仪设计并制作了能够耐受浓硫酸的平行板夹具,揭示不同分子量PPTA/H_(2)SO_(4)溶液的相转变和剪切流变行为。通过偏光显微镜观察PPTA/H_(2)SO_(4)溶液的液晶织构,结合流变的线性黏弹性,确定相转变温度和边界。通过流变的振荡扫描以及稳态剪切,探索温度、质量分数和PPTA分子量与溶液的储能模量、松弛时间和黏度的关系。结果表明:更高浓度的PPTA/H_(2)SO_(4)溶液具有更宽的向列相(N)的温度范围,并且相转变临界温度也更高;模量、松弛时间和黏度随着浓度增加呈现非单调的变化;高浓度溶液在稳态剪切中表现出非线性流变行为。进一步理解PPTA/H_(2)SO_(4)溶液的相转变条件以及剪切流变行为,将会对对位芳纶纺丝工艺参数的指导与改进有着重要意义。
Poly(p-phenylene terephthalamide)(PPTA)can be dissolved in concentrated sulfuric acid(H_(2)SO_(4))and exhibits a liquid crystalline phase within a certain temperature and concentration range.It can be spun into para-aramid fibers through the dry-jet wet spinning process.The phase behavior and rheological behavior of PPTA/H_(2)SO_(4) solutions are key factors determining the processing technology and performance of para-aramid fibers.However,there is a lack of convenient research tools.In this paper,a parallel plate fixture resistant to concentrated sulfuric acid was designed and fabricated for a rotational rheometer to reveal the phase transition and shear rheological behavior of PPTA/H_(2)SO_(4) solutions with different molecular weights.The liquid crystalline texture of PPTA/H_(2)SO_(4) solutions was observed by polarizing microscopy,and the phase transition temperature and boundaries were determined in combination with the linear viscoelasticity of rheology.The relationship between temperature,mass fraction,PPTA molecular weight and the storage modulus,relaxation time and viscosity of the solution was explored through rheological oscillation scanning and steady shear.The results show that higher concentration PPTA/H_(2)SO_(4) solutions have a wider temperature range of the nematic phase(N)and a higher critical temperature for phase transition;the modulus,relaxation time and viscosity show non-monotonic changes with increasing concentration;high concentration solutions exhibit nonlinear rheological behavior in steady shear.A further understanding of the phase transition conditions and shear rheological behavior of PPTA/H_(2)SO_(4) solutions will be of great significance for guiding and improving the spinning process parameters of para-aramid fibers.
作者
赵鸣
唐凯
雒瑞银
李京津
马千里
刘庚鑫
滕翠青
ZHAO Ming;TANG Kai;LUO Rui-yin;LI Jing-jin;MA Qian-li;LIU Geng-xin;TENG Cui-qing(State Key Laboratory of Advanced Fiber Materials,Center for Advanced Low-dimension Materials,College of Materials Science and Engineering,Donghua University,Shanghai 201620,China;Ningxia Taihe Aramid Fiber Co.,Ltd.,Ningxia 750411,China;Tayho Advanced Materials Group Co.,Ltd.,Yantai 264006,China;State Key Laboratory of Advanced Fiber Materials,College of Materials Science and Engineering,Donghua University,Shanghai 201620,China)
出处
《高分子通报》
北大核心
2025年第8期1291-1298,共8页
Polymer Bulletin
基金
国家重点研发计划(项目号2021YFB3700102)
国家自然科学基金(基金号22473025)
上海市科技创新行动计划自然科学基金(基金号22ZR1401300)。
关键词
聚对苯二甲酰对苯二胺
相转变
模量
稳态剪切黏度
Poly(p-phenylene terephthalamide)
Phase transition
Modulus
Steady-state shear viscosity
