以丙烯酰胺(AM),2-丙烯酰胺-2-甲基丙磺酸钠(AMPSNa)和甲基丙烯酸十六烷基酯(MPA)为单体[n(AM)∶n(AMPSNa)∶n(MPA)=35∶4.5∶0.5],0.1%过硫酸钾/亚硫酸氢钠为引发剂,于35℃聚合4 h合成了一种疏水缔合聚合物型压裂液增稠剂(AF),其形貌...以丙烯酰胺(AM),2-丙烯酰胺-2-甲基丙磺酸钠(AMPSNa)和甲基丙烯酸十六烷基酯(MPA)为单体[n(AM)∶n(AMPSNa)∶n(MPA)=35∶4.5∶0.5],0.1%过硫酸钾/亚硫酸氢钠为引发剂,于35℃聚合4 h合成了一种疏水缔合聚合物型压裂液增稠剂(AF),其形貌和增稠性能经TEM和流变仪表征。结果表明:AF在水溶液中可形成密集的空间网络结构;CACAF为1 200 mg·L-1。以白油为外相,甲醇为内相,AF为增稠剂,制备了油醇浓缩缔合聚合物压裂液增稠剂CAF,其性能经流变仪和表面张力仪表征。结果表明:0.65%CAF于140℃/170 s-1剪切1 h,表观黏度为77.1 m Pa·s,高温抗剪切性较好;于95℃破胶3 h,破胶液表观黏度,表面张力和残渣含量分别为1.32 m Pa·s,26.9 m N·m-1和25.8 mg·L-1,破胶返排性较好。展开更多
Eight 6FDA-TFDB polyimide(PI)samples with absolute molecular weights ranging from 1.25 × 10^5 g mol^-1 to 3.11 × 10^5 g mol^-1 are obtained by precipitation fractionation.Rheological experiments are conducte...Eight 6FDA-TFDB polyimide(PI)samples with absolute molecular weights ranging from 1.25 × 10^5 g mol^-1 to 3.11 × 10^5 g mol^-1 are obtained by precipitation fractionation.Rheological experiments are conducted to determine the influence of molecular weight on the associating behavior of PI in A/X-dimethylformamide(DMF)solutions in a broad volume fraction,including abnormal steady shear flow,solution heterogeneity,and scaling behavior.Abnormal flow behaviors,i.e.,multi-region shear thinning and weak shear thickening,are studied,and these behaviors have not been reported in literature.The heterogeneity of PI/DMF solutions is examined by dynamic rheological test.By plotting qsp versus four concentration regions of l-IV can be distinguished for all PI samples with various molecular weights.The scaling results in different concentration regions are in good agreement with the associative polymer theory proposed by Rubinstein and Semenov.The scaling exponents do not show molecular weight dependence in concentration regions I and II.In concentration regions Ⅲ and Ⅳ,the scaling exponents change little when the molecular weight is below 242 k but increase when the molecular weight increases from 242 k to 311 k.This work can help us to understand polyimide solution properties from dilute to semidilute entangled solutions,and will guide the polyimide solution preparation for different processing.展开更多
文摘以丙烯酰胺(AM),2-丙烯酰胺-2-甲基丙磺酸钠(AMPSNa)和甲基丙烯酸十六烷基酯(MPA)为单体[n(AM)∶n(AMPSNa)∶n(MPA)=35∶4.5∶0.5],0.1%过硫酸钾/亚硫酸氢钠为引发剂,于35℃聚合4 h合成了一种疏水缔合聚合物型压裂液增稠剂(AF),其形貌和增稠性能经TEM和流变仪表征。结果表明:AF在水溶液中可形成密集的空间网络结构;CACAF为1 200 mg·L-1。以白油为外相,甲醇为内相,AF为增稠剂,制备了油醇浓缩缔合聚合物压裂液增稠剂CAF,其性能经流变仪和表面张力仪表征。结果表明:0.65%CAF于140℃/170 s-1剪切1 h,表观黏度为77.1 m Pa·s,高温抗剪切性较好;于95℃破胶3 h,破胶液表观黏度,表面张力和残渣含量分别为1.32 m Pa·s,26.9 m N·m-1和25.8 mg·L-1,破胶返排性较好。
基金the National Basic Research Program of China(No.2014CB643604)the National Natural Science Foundation of China(No.51173178).
文摘Eight 6FDA-TFDB polyimide(PI)samples with absolute molecular weights ranging from 1.25 × 10^5 g mol^-1 to 3.11 × 10^5 g mol^-1 are obtained by precipitation fractionation.Rheological experiments are conducted to determine the influence of molecular weight on the associating behavior of PI in A/X-dimethylformamide(DMF)solutions in a broad volume fraction,including abnormal steady shear flow,solution heterogeneity,and scaling behavior.Abnormal flow behaviors,i.e.,multi-region shear thinning and weak shear thickening,are studied,and these behaviors have not been reported in literature.The heterogeneity of PI/DMF solutions is examined by dynamic rheological test.By plotting qsp versus four concentration regions of l-IV can be distinguished for all PI samples with various molecular weights.The scaling results in different concentration regions are in good agreement with the associative polymer theory proposed by Rubinstein and Semenov.The scaling exponents do not show molecular weight dependence in concentration regions I and II.In concentration regions Ⅲ and Ⅳ,the scaling exponents change little when the molecular weight is below 242 k but increase when the molecular weight increases from 242 k to 311 k.This work can help us to understand polyimide solution properties from dilute to semidilute entangled solutions,and will guide the polyimide solution preparation for different processing.
