Ultradrawing and ultimate tensile properties of novel ultra-high molecular weight polyethylene composite fibers filled with nanoalumina fillers

Novel ultra-high molecular weight polyethylene (UHMWPE)/nanoalumina (F(100)A(y)), UHMWPE/acid-treated nanoalumina (F(100)A(ox%-8-y)) and UHMWPE/functionalized nanoalumina (F(100)A(ox%-8)(1)PE(g-MAH)(y)(x)) as-prepared nanocomposite fibers were prepared by gel-spinning processes. The rod-like features of the original nanoalumina fillers were significantly etched into broken/shorter nanorods and/or shreds by oxalic acid solutions as their concentrations and/or treating time increased. As evidenced by Fourier transform infrared and transmission electron microscopy analysis, PEg-MAH molecules were successfully grafted onto acid-treated nanoalumina fillers through the reaction of the hydroxyl groups of nanoalumina fillers with the maleic anhydride groups of PEg-MAH molecules during their modification processes. The specific surface areas of each A(ox%-8)(1)PE(g-MAH)(y)(x) functionalized nanoalumina filler reached a maximum value (470m(2)/g), as the weight ratios of PEg-MAH to acid-treated nanoalumina approached the optimal value at 8. The achievable draw ratio (D-ra) values of F(100)A(y), F(100)A(ox%-8-y) and/or F(100)A(ox%-8)(1)PE(g-MAH)(y)(x) as-prepared fibers approach a maximal value as the original, acid-treated and/or functionalized nanoalumina contents reach the optimal values at 0.1, 0.1 and 0.075phr, respectively, in which, the maximal D-ra values obtained for F(100)A(ox%-8)(1)PE(g-MAH)(0.075)(x) as-prepared fiber specimens are significantly higher than those of the F(100)A(0.1) and F(100)A(ox%-8-0.1) drawn fiber specimens prepared at the same draw ratios. Moreover, the maximal D-ra values obtained for F(100)A(ox%-8)(1)PE(g-MAH)(0.075)(x) as-prepared fibers reached another maximal value as the functionalized nanoalumina fillers were modified using the optimal weight ratio of PEg-MAH to acid-treated nanoalumina at 8. Further investigation revealed that excellent orientation and tensile properties of the UHMWPE nanocomposite fibers can be obtained by ultradrawing the F(100)A(ox%-8)(1)PE(g-MAH)(y)(x) as-prepared fibers with proper amounts of well-dispersed functionalized nanoalumina fillers.