Polyester nonwoven fibrous material is widely used in construction and automobile industries for thermal insulation purposes. It is worthy and meaningful to understand the effect of structural parameters on the thermal property. Fiber orientation, as one of the most vital parameters, has a significant effect on thermal property. However, there has been little quantitative analysis focusing on this aspect. This paper theoretically and experimentally analyzes the thermal conductivity of samples with varying fiber orientation. Existing models were selected to predict the thermal conductivity of polyester nonwoven samples. Two different apparatus were applied to carry out the experimental measurements. The relative differences between the predicted and measured results were compared. One commonly used model was modified for accurate prediction. It was shown that some existing models under- or overestimate the thermal conductivity compared to the measured values. The results indicate that the modified model can accurately predict the thermal conductivity of polyester nonwoven materials within a 0.2% relative difference.

The development of environmentally friendly, multifunctional conductive membranes is an ideal candidate for future new electronic components. Some cellulose-based electronic sensors have been studied, such as pressure sensors, hydrothermal sensors, flexible sensors, optoelectronic devices, and electrochemical energy storage, etc. However, there are very few studies on cellulose-based conductive materials in Joule heating. In this study, we adopted a simple and environmentally friendly silane crosslinking method to crosslink cellulose and graphene oxide (GO) together. The cellulose/GO hybrid membrane were characterized by FTIR, Raman, SEM, AFM, TGA, surface wettability, self-cleaning, surface resistance, Joule heating and other tests. Results showed that the covalent bond between cellulose and GO was formed by vinyltrimethoxysilane (VTMS), and GO was successfully cross-linked on the surface of the cellulose membrane. The cellulose/GO hybrid membrane has good thermal stability, strong hydrophobicity and self-cleaning properties. When the GO concentration was 3 w/w%, the Young's modulus of the film reached the maximum (47.38% higher than that of the original sample). In addition, it also exhibited extremely low surface resistivity (720.69 Ω), controllable Joule heating capability, extremely fast thermal response (heating process and cooling process within 5 s) and good electrothermal stability. It showed great potential in multi-functional electronic products such as electric heating electronic devices, electric heating sensors, and smart clothing in the future.

The cellulose/polyvinyl alcohol (PVA)/expanded graphite (EG) 3D porous foam, which has wide application prospects in cost-effective dye removal, was prepared by physical crosslinking and foaming technology. The prepared foam material has an obvious 3D network and porous structure, exhibiting excellent removal efficiency for methylene blue (MB) in an aqueous solution. The largest MB adsorption capacity of the foam is 110.81 mg/g. The adsorption process follows the pseudo-2^nd order kinetics and the Freundlich isotherm model, indicating that the adsorption process is controlled by active surface sites and the physical adsorption process. Thermodynamic studies have shown that the adsorption process is a spontaneous and exothermic reaction. After five cycles of adsorption experiments, the composite material still exhibited a more than 70% dye removal rate. Results show that cellulose/PVA/EG 3D porous foam is an effective, promising, and recyclable adsorbent, which can be used to remove MB from aqueous solutions.

Based on the current rapid development of electronic products, the development of light-weight, processable, environmentally friendly, long-life, durable, less corrosive, and tunable conductive composite materials with multiple applications may be the development direction of next-generation electronic devices. In this work, for the first time, we employed 3-Mercaptopropyltrimethoxysilane (3-MT) to modify viscose nonwovens and enhance the copper plating process. The prepared samples were characterized by Fourier transform infrared, Wide-angle X-ray diffraction (WAXD), scanning electron microscope + energy dispersive X-ray spectroscopy (SEM + EDS), thermogravimetric analysis (TGA), electrical resistivity, anti-corrosion, Joule heating, and electromagnetic interference (EMI) shielding. Results showed that 3-MT was covalently bound to the viscose surface through hydrolysis and condensation reactions and introduced SH groups. WAXD confirmed that the thiol modification did not change the internal crystal structure of viscose and copper ions. TGA and surface morphology analysis confirmed that the modified viscose promoted the deposition of metal particles in the copper plating process due to the affinity of thiol to metal so that copper particles almost completely wrapped the viscose fibers. In addition, 3MT@Cu@Viscose exhibits extremely low surface and volume resistivity (346.6 and 333.2 mΩ·m), improved corrosion resistance (corrosion rate reduced by 58% compared to the unmodified sample), fast Joule heating response (within 10 s) in low voltage (1 V) and excellent EMI shielding effectiveness (EMI SE > 50 dB). It showed great potential in future multi-functional electronic products such as electric heating sensors, smart clothing, and EMI shielding barrier.