Influence of annealing treatment on the structure and properties of poly(4‐methyl‐1‐pentene)‐based films and membranes

Abstract

The poly(4‐methyl‐1‐pentene) casting films were prepared by melt extrusion and annealed below the melting temperature. The effect of annealing conditions on the structure and properties of casting films and stretched membranes was discussed. In this work, a new peak around annealing temperature, as shown in melting curves, revealed the increase in thickness of lamellar structure. Annealing treatment led to improvements of amorphous thickness and crystal orientation. And the thickness of crystal phase correlated with the logarithm of annealing time. The increase in annealing temperature or time led to the improvements of the hard elasticity of samples. Additionally, the larger porosity of stretched membranes was observed as the annealing time and temperature increased. An optimum annealing condition to prepare microporous membranes was 30 min, 200 °C. This work also discussed the importance of annealing treatment in the preparation of microporous membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46491.

Influence of crystal orientation on stretching induced void formation in poly(4‐methyl‐1‐pentene) investigated by in‐situ small‐angle and wide‐angle X‐ ray scattering

“…It can be found that f H was 0.49 and the crystallinity was 0.38 in P4MP1‐ref, and they were enlarged to 0.52 and 0.40, respectively, when T h was 150°C. As shown in Figure 2, no additional melting peak arose, so the increase of f H and the crystallinity was probably caused by the lamellae perfection and molecular chains rearrangement in the amorphous phase 25,41,42 . As T h was higher than 223°C and lower than 234°C, part of the previously existed crystals was melted.…”

“…For the P4MP1 precursor film, the optimum annealing temperature and time were 205°C and 20 min, and the best cold and hot stretching temperatures were 70 and 180°C 23 . In the later work by Yin et al, 24–26 P4MP1 precursor film with different draw ratios was obtained and the optimum annealing parameters and stretching parameters were discussed. It was found that the crystallinity of the precursor film declines with increasing draw ratios.…”

“…During extrusion, a larger molecular weight, higher extrusion speed, and a larger quench height promote the formation of planar stacked lamellar texture and higher main-chain crystalline orientation factor. 21 For the P4MP1 precursor film, the optimum annealing temperature and time were 205 C and 20 min, and the best cold and hot stretching temperatures were 70 and 180 C. 23 In the later work by Yin et al, [24][25][26] P4MP1 precursor film with different draw ratios was obtained and the optimum annealing parameters and stretching parameters were discussed. It was found that the crystallinity of the precursor film declines with increasing draw ratios.…”

“…The optimum annealing temperature and time were 200 C and 30 min. 25 The variation of the optimum annealing condition is of great possibility caused by the different molecular weight and extrusion parameters. In the stretching stage, low temperature and faster stretching speed resulted in more voids and larger void sizes.…”

“…During the annealing treatment, the thickness of the crystalline phase is a function of annealing time. The optimum annealing temperature and time were 200°C and 30 min 25 . The variation of the optimum annealing condition is of great possibility caused by the different molecular weight and extrusion parameters.…”