Preparation and performance of ultrafiltration membranes based on stretch⁃expanded polyethylene separators

doi:10.19491/j.issn.1001-9278.2025.11.007

Abstract

Abstract:

Conventional polyethylene （PE） membranes show promise as substrates for ultrafiltration and reverse osmosis membranes but are limited by poor hydrophilicity， low porosity， and consequently low water flux. To address these issues， this study investigates the effects of pore expansion via stretching and hydrophilic modification on the pore structure and water flux of PE membranes. Pore structure was tailored through a stretch⁃expansion process， which increased porosity and pore size while reducing pore tortuosity， thereby enhancing filtration efficiency. Additionally， hydrophilic modification was achieved by crosslinking the membrane with a sodium polyacrylate coating. The modified membranes maintained a high bovine serum albumin （BSA） retention rate while demonstrating significantly improved water flux. The results indicated that a stretch ratio of 2 yielded optimal membrane properties， with porosity increasing to 80% and pore tortuosity decreasing to 1.6. The stretched and coated PE membranes exhibited markedly enhanced hydrophilicity， water flux， and BSA retention compared to unmodified PE membranes. The modified PE porous membrane can be directly applied as an ultrafiltration membrane and also provides a smooth， suitable surface for interfacial polymerization， making it a promising substrate for reverse osmosis membranes.

Key words: polyethylene, separator, expanding holes, hydrophilic modification, sodium polyacrylate, ultrafiltration membrane

CLC Number:

TQ325.1⁺2

HU Yutao, ZHANG Lun, QIAO Mengjiao, MA Ke, SONG Hongqin, WANG Li, WAN Caixia. Preparation and performance of ultrafiltration membranes based on stretch⁃expanded polyethylene separators[J]. China Plastics, 2025, 39(11): 41-46.

Figures/Tables 8

样品编号	拉伸倍率	拉伸温度/℃	拉伸速率/mm·s^-1
L1	-	-	-
L1.5	1.5	125	2
L2	2.0	125	2
L2.5	2.5	125	2

Tab.1. Stretching process parameters

Fig.1. Schematic diagram of preparation of ultrafiltration membrane using PE porous membrane

Fig.2. Changes in pore structure of PE porous membrane after hole enlargement

Fig.3. Changes in through⁃hole diameter before and after expansion

Fig.4. The apparent morphology of L1［（a）、（b）］ and L2［（c）、（d）］ membranes

Fig.5. Fourier transform infrared spectroscopy （a） and contact angle （b） of L2 and L2+PAAS membranes

Fig.6. The surface morphology of L1+PAAS （a） and L2+PAAS （b） samples

Fig.7. Water flux and retention rate for BSA of PE porous membrane ultrafiltration membrane before and after hole enlargement

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