Combined effects of nanoparticle and stretch‐induced orientation on crystal structure and properties of UHMWPE/TiO₂ composite microporous membranes

Abstract

The nanocomposite microporous membrane of ultra-high molecular weight polyethylene (UHMWPE) and nano-titanium dioxide (nano-TiO 2 ) system was prepared by combining the thermally induced phase separation (TIPS) technique with the extrusion-casting process using liquid paraffin (LP) as the diluent. The effects of variations of TiO 2 content and melt draw ratio on the properties of composite microporous membranes were studied and the optimal processing parameters were further investigated. ATR-FTIR demonstrated that nanocomposite microporous membranes were successfully prepared. The crystallization behavior and morphological evolution of membranes were systematically investigated by WAXD, 2D-SAXS, and SEM. It was found that the stretch-induced orientation of UHMWPE was promoted and the shish-kebab structure was formed for the reason of addition of TiO 2 . The mechanism of combined effects of nanoparticles and stretch-induced orientation on the crystallization behavior of UHMWPE was further discussed and explained. Compared to pure UHMWPE film, the permeability of the optimum performance film was significantly improved, with porosity of 49% and pure water flux of about 193 L m À2 h À1 . Mechanical studies showed that nanoparticles and DR have significant effects on tensile strength and elongation at break. In addition, the thermal stability of composite microporous membranes was found to be improved with the increase of TiO 2 content and melt draw ratio. Thus, this investigation delivers inspiration for the expansion of excellent performance microporous membranes used for battery separators and filtration devices.

Engineering Polymer-Based Porous Membrane for Sustainable Lithium-Ion Battery Separators

“…In recent years, scientists have focused primarily on functionalizing PE membranes through surface modification to enhance properties including wettability, strength, and thermal and dimensional stability, encompassing both inorganic and organic coatings [ 23 , 81 , 178 , 179 ]. Specifically, inorganic reinforcement materials, such as SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 and so on, can be incorporated into the PE matrix to prevent membrane deformation under elevated temperature conditions and further enhance the safety of LIBs, due to their excellent heat resistance and function as a physical skeleton [ 81 , 173 , 180 ].…”

“…Notably, UHMWPE has occupied a substantial market share in commercial LIB separators, owing to its superior microporous structure, puncture resistance, mechanical strength, chemical resistance, cost-effectiveness, thermal stability, and so on [ 173 , 174 , 175 , 176 , 177 ]. Just like conventional PE-based components, the performance of a UHMWPE membrane can also be enhanced when used as a battery separator through the introduction of inorganic materials (e.g., SiO 2 , Al 2 O 3 , TiO 2 , and ZrO 2 ) and organic materials (e.g., PVDF, PMMA) to enhance thermal stability and improve the safety of LIBs [ 173 , 180 ]. As an illustration, Babiker et al [ 99 ] efficiently engineered and industrialized UHMWPE/SiO 2 nanocomposite membranes for the first time by means of a biaxial stretching without additional post-modifications.…”

Experimental and numerical investigations of VO2‐UHMWPE polymer composite plates across phase change temperature

“…5,6 Among the pool of polymers, ultrahigh molecular weight polyethylene (UHMWPE) is extensively explored for biomedical [7][8][9] and ballistic applications. [10][11][12][13][14][15][16] Owing to high tensile strength and flexibility, UHMWPE has a low melting temperature (<155 C) and is viscoelastic, thus can only be utilized in a low-temperature window. 17,18 VO 2 -based UHMWPE polymer composite was recently explored for its high-temperature mechanical strength by the split Hopkinson pressure bar test by Verma et al 19 It was shown that above 75 C, the VO 2 -based UHMWPE exhibits increased dynamic mechanical strength, because of the phase transition of VO 2 from monoclinic to tetragonal, consequently leads to an increase in elastic modulus and hardness.…”