Utilization of supercritical CO2 as a processing aid for preparation of ultrahigh molecular weight polyethylene/functionalized activated nanocarbon fibers

Abstract

This is the first investigation to report the processing and properties of ultrahigh molecular weight polyethylene (UHMWPE)/functionalized activated nanocarbon (FANC) gel solutions with the aid of supercritical carbon dioxide (scCO2). The ultradrawing and ultimate tensile properties of scCO2UHMWPE and scCO2UHMWPE/FANC fibers were found to improve considerably compared to those of UHMWPE and UHMWPE/FANC fibers prepared in the conventional way. The maximum achievable draw ratio obtained for the optimal scCO2UHMWPE/FANC fibers drawn at 95°C reached 445. The highest tensile tenacity (σf) of the fully drawn scCO2UHMWPE/FANC fiber reached an extraordinary high value of 104 g/d, which is about 3.2 and 1.1 times of that of the optimal UHMWPE and UHMWPE/FANC fully drawn fibers, respectively. The σf obtained for the optimally fully drawn scCO2UHMWPE/FANC fiber is about 25 times of those of steel fibers and is the highest tensile tenacity ever reported for single‐stage drawn polymeric fibers. Considerably lower dynamic transition temperatures and evaluated thinner crystal lamellae nucleated off of extended chains or FANC nucleants were found for as‐prepared scCO2UHMWPE and scCO2UHMWPE/FANC fibers compared with UHMWPE and UHMWPE/FANC fibers, respectively. Specific surface area, morphological, and Fourier transform infrared analyses of the activated nanocarbon (ANC), acid‐treated activated nanocarbon (ATANC) and FANC nanofillers and investigation of thermal, morphological, and orientation factor properties of the as‐prepared and drawn UHMWPE, UHMWPE/FANC, scCO2UHMWPE, and scCO2UHMWPE/FANC fibers were performed to understand the remarkable ultradrawing, dynamic transition, and ultimate tensile properties obtained for scCO2UHMWPE and scCO2UHMWPE/FANC fibers. POLYM. ENG. SCI., 59:1462–1471 2019. © 2019 Society of Plastics Engineers