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Melt spinning and stretching process was used to prepare polyurethane/poly(vinylidene difluoride) (PU/PVDF) blend hollow fibre membrane in this study. Rheological properties of melts of PU, PVDF and their blends were studied by observing their melting viscosity changing with shear rate and temperature. Morphologies of PU/PVDF blend hollow fibre membranes with different mass ratios were also observed by SEM and results showed that PU/PVDF mass ratio of 3:1 was relatively better condition for membrane preparation. The forming mechanism of the interfacial microvoids in PU/PVDF blends was also investigated and PU/PVDF blend hollow fibre membrane with water flux of ∼2174 L m−2 h−1 was finally obtained under the pressure of 0·1 MPa.

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A dual‐scale ablation model was developed to address the lack of research on the influence of weaving parameters of gradient 3D woven composites on the ablation performance. It consists of a mesoscale heat transfer model and a macroscale ablation model, and they are effectively connected by parametric conduction. By comparing with experimental results, the accuracy of the model was demonstrated. The effect of yarn spacing, recession resistant layer thickness on the thermal protection performance of gradient 3D woven composite was investigated. Furthermore, the effect of each weaving parameter on the integrated performance of ablation resistance, thermal insulation and light‐weight level is evaluated. The results show each weaving parameter has a substantial impact on thermal protection performance, with weft spacing and binder yarn spacing being the most significant influence. Reasonable design of these parameters can facilitate the comprehensive performance of composites. These results serve as a useful reference for refinement design of thermal protection materials.

Surface emissivity is an essential parameter for thermal radiation, which greatly influences thermal protection materials (TPMs) under high temperature. In the present study, dual-scale models of 2.5D woven carbon fiber fabric reinforced resin-based composites are built with different weaving parameters of fabric, to investigate the meso-structure influence on the surface emissivity, and the surface emissivity for different composites is calculated based on discrete ordinate method (DOM). Two morphological indexes are proposed to further analyze the effect of meso-structure characteristics on emissivity. The results show that the surface emissivity is mainly determined by the ablated woven composite within a certain depth. More compact in-plain weaving architecture improves surface emissivity, while more compact through-thethickness weaving architecture reduces the surface emissivity of 2.5D woven ablative composites. The meso-structure with a lower roughness factor and a higher specific surface area leads to intense surface radiation. This study can provide scientific guidance for the design of 2.5D woven ablative composite for thermal protection.

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