Anisotropic polyimide (PI)/graphene composite aerogels were fabricated by unidirectional freezing. A poly­(amic acid) (PAA) ammonium salt/graphene dispersion was first synthesized by mixing together PAA, H2O, triethylamine (TEA), and graphene and then was successively subjected to one-way freezing, freeze-drying, and thermal imidization. The one-way growth of ice crystals endowed the composite aerogels with highly arranged tubular pores. The PI/graphene composite aerogels possessed anisotropic conductivity, electromagnetic interference (EMI) shielding, heat transfer, and compression performance. Moreover, the composite aerogels with low density (0.076 g·cm–3) exhibited high EMI shielding effectiveness (SE) of 26.1–28.8 dB, and its specific EMI SE value achieved 1373–1518 dB·cm2·g–1 when the graphene content was 13 wt %. The main electromagnetic interference shielding mechanism of these composite aerogels was microwave absorption. The composite aerogels had excellent thermal stability, and their 5% weight loss temperature was higher than 546 °C in nitrogen. This research provided an easy and environmentally friendly approach to prepare lightweight and anisotropic PI-based composite aerogels.

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The dynamic rheological behavior of low‐density polyethylene (LDPE)/ultra‐high‐molecular‐weight polyethylene (UHMWPE) blends and linear low‐density polyethylene (LLDPE)/UHMWPE blends was measured in a parallel‐plate rheometer at 180, 190, and 200°C. Analysis of the log–additivity rule, Cole–Cole plots, Han curves, and Van Gurp curves of the LDPE/UHMWPE blends indicated that the blends were miscible in the melt. In contrast, the rheological properties of LLDPE/UHMWPE showed that the miscibility of the blends was decided by the composition of LLDPE. The differential scanning calorimetry results and scanning electron microscopy photos of the LLDPE/UHMWPE blends were consistent with the rheological properties, whereas with regard to the thermal and morphological properties of LDPE/UHMWPE blends, the results reveal three endothermic peaks and phase separation, which indicated a liquid–solid phase separation in the LDPE/UHMWPE blends. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Some oxygen containing groups (mainly the CO group) are formed on the molecular chain of high density polyethylene (HDPE) during electron beam irradiation in air. The affinity between HDPE and sericite‐tridymite‐cristobalite (STC), the dispersion of STC in the HDPE matrix, and the mechanical properties of the HDPE/STC blend are improved quite a lot by the introduction of polar groups. Compared with HDPE, the tensile and impact strength of electron beam irradiated HDPE (30 kGy)/STC (60/40) are increased to 29.0 MPa and 518 J/m, respectively, from 24.5 MPa and 215 J/m; the tensile and impact strength of irradiated HDPE (30 kGy)/STC (50/50) are 31.1 MPa and 424 J/m, respectively. The Ceast impact test showed that the increase of impact strength was mainly due to the strong interfacial adhesion between irradiated HDPE and STC, thus preventing the spreading of cracks over wide areas. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 243–249, 2000