Preparation of iPP/PE⁃HD/iPP Trilayer Microporous Membranes Through Viscous Encapsulation

doi:10.19491/j.issn.1001-9278.2020.05.002

Abstract

Abstract:

The mechanisms of phase separation and control method of multiphase system in the flow field were studied by capillary rheometer, and then a series of isotactic polyethylene (iPP)/polyethylene (PE?HD)/iPP trilayer blend membranes were prepared by a casting method according to a viscous encapsulation principle. The blend membranes with different phase structures were obtained by premixing iPP with PE?HD. The results indicated that the actual area of PE?HD in the blend membranes was 94 % and the porosity of blend membranes was as high as 51.82 %. The blend membrane containing 25 wt% iPP exhibited a more uniform distribution in pore size, and its macropore content was 84 % when the draw ratio reached 50 times. The study of formation mechanism for complex pores indicated that there was a complexity in the formation of intermediate layer in the blend membranes. Moreover, this work also confirmed the importance of crystalline structure and microporous morphology of the interfacial layer upon the properties of the blend membranes.

Key words: trilayer microporous membrane, viscous encapsulation, phase separation

CLC Number:

TQ325.1

Ya ZHANG, Chao DING, Wenbo CHEN, Mingbo YANG. Preparation of iPP/PE⁃HD/iPP Trilayer Microporous Membranes Through Viscous Encapsulation[J]. China Plastics, 2020, 34(5): 9-15.

Figures/Tables 12

Fig.1. Rheological properties of the selected materials

Fig.2. PLM of samples with different ratios of length to diameter

Fig.3. Ap of samples with different ratios of length to diameter

Fig.4. Encapsulation structures from different methods

Fig.5. The influence of annealing time on the porosity of the trilayer microporous membrane

Fig.6. The cross section of tri?layer microporous membrane of this method and coextrusion

Fig.7. Surface morphology of different iPP/PE?HD blends with different mass ratios

Fig.8. SEM of surface morphology of precursor film and microporous membrane of specimens P50 and P25 with different draw ratios

Fig.9. DSC curves of the precursors P25 with different draw ratios

牵引比	PE?HD		iPP
牵引比	T_m/℃	X_C/%	T_m/℃	X_C/%
30	128.89	61.25	165.89	44.50
40	129.36	61.80	165.80	46.96
50	129.50	63.30	165.58	44.91

Tab.1. The melting point and crystallinity of PE?HD and iPP of the specimens P25 with different draw ratios

Fig.10. Surface morphology of two kinds of microporous membranes

Fig.11. The micropore analysis of blend microporous membrane and trilayer microporous membrane

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