This article presents the mechanical properties of polyvinylchloride-coated fabrics with Precontraint® technology. First, groups of off-axial tests are carried out, and the corresponding strength criteria are discussed. Then, the biaxial tests are carried out on the material without initial loading and the material after cyclic loading, and the corresponding stress–strain surfaces are studied. Finally, the effects of temperature on the mechanical properties are studied. Results show that this material is typically orthotropic and its strength can be predicted by the Tsai–Hill strength criterion. The differences between the mechanical properties of the warp and the weft are not significant, because the Precontraint® technology used in the processing reduces significantly the discrepancies, compared with common plain woven fabrics. The material without initial loading is nonlinear and viscoelastic, and after cyclic loading it becomes linear and its stiffness increases. The biaxial tensile behaviors are affected by biaxial loading significantly, and then different constitutive relations should be conducted regarding to different service conditions. With temperature increasing, the tensile strength and the elastic modulus gradually decreases, and the breaking strain increases.

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In this study, paraffin/red mud phase change energy storage composites were fabricated at 4 mix proportions with paraffin to red mud ratios of 0.4:0.6, 0.45:0.55, 0.5:0.5, and 0.55:0.45 by a mixed mill-heating method. Scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) results reveal that paraffin flows well into red mud pores and has good compatibility. The differential scanning calorimetry (DSC) results reveal that the melting temperatures of the paraffin/red mud phase change energy storage composite vary from 75℃ to 85℃, and the latent heat 2 value is approximately 25~40J/g. High thermal stability is observed by the thermogravimetric analysis (TG) method. The Brunauer Emmett Teller (BET) isotherms, laser particle sizer, X-ray diffraction analysis (XRD), and laser Raman spectrograph (LRS) show that the phase change energy storage composite does not produce a new material from the raw materials and that the material has a stable performance. Furthermore, the paraffin/red mud phase change energy storage composite was incorporated into the cement-based and gypsum-based materials at 10%, 20%, and 30% weight. The heat storage performance can be improved remarkably with an increase in the addition of phase change energy storage composite replacement. The compressive strength change is minimal with the addition of 10% and 20%, and the compressive strength decreases by nearly 40% with the addition of 30%. The paraffin/red mud phase change energy storage composite has a large influence on the flexural strength.

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