Porous materials hold great potential in the field of sound absorption, but the most abundantly used materials, such as Polyurethane (PU) foam and polyvinyl chloride (PVC) foam, would inevitably bring environmental harms during fabrication. In this study, the nontoxic addition-molded room temperature vulcanized silicone rubber is chosen as the matrix, and NaCl particles are chosen as the pore forming agent to prepare open cell foams via the dissolve-separating foaming method. The effect of different amounts of NaCl (0–100 phr) on the cell structure, mechanical and sound absorption properties is investigated and analyzed. The results indicate that the cell structure could be tailored via changing the addition amount of NaCl, and open cell silicon rubber foams could be achieved with more than 20 phr NaCl addition. Open cell silicon foams show the most effective sound absorption for sound waves in middle frequency (1000–2000 Hz), which should be attributed to the improved impedance matching caused by the open cell structures. Additionally, the mechanical properties, including hardness, tensile strength and corresponding elastic properties, gradually decay to a steady value with the increasing addition amount of NaCl. Therefore, open cell silicone rubber foams are capable of sound absorption in middle frequency.

Polyaniline/bentonite was used in this study to investigate its adsorption behaviors of reactive green 19. Influencing factors including contact time, pH, temperature and inorganic salts were investigated.The adsorption kinetic data fitted the pseudo-second-order model better than the pseudo-first-order and Elovich models, and the Langmuir model was better than the Freundlich model to describe the adsorption process. Thermodynamic studies indicated that the adsorption of reactive green 19 by polyaniline/bentonite was an endothermic and spontaneous process. Experimental data indicated that both NaCl and Na 2 SO 4 could improve the reactive green 19 adsorption as a result of aggregation of the dye molecules in solution induced by the inorganic salts, and an increase of pH value from 5 to 9 caused a slight decrease in reactive green 19 adsorption.

No abstract

Flexible epoxy‐dispersed liquid crystal membranes (EDLC‐v membranes) with high thermal conductivity were successfully prepared by using of high voltage orientation molding. Liquid crystal monomer (LCM) was uniformly dispersed into flexible epoxy polymers cured by trimethylolpropane tris(3‐mercaptopropionate) (TTMP) or pentaerythritol tetra(3‐mercaptopropionate) (PETMP). In‐plane thermal conductivity (TC//) of EDLC‐v membranes reached to 1.47 W m−1 K−1 with LCM content of 30 wt%, which was 5.65 times higher than that of epoxy polymers without LCM (0.26 W m−1 K−1). In addition, the tensile strength and elongation at break of EDLC‐v membranes were up to 27.9 MPa and 92.8%, respectively. The main reasons for high TC// and flexibility of EDLC‐v membranes are molecular chains' ordered arrangement, crosslinking in epoxy polymers, hydrogen bond interaction, and high voltage orientation molding. This work provided a new and feasible way to prepare intrinsic high thermal conductive polymer materials, as well as flexible epoxy polymers.

The practical application of polymer composites in the electronic and communications industries often requires multi-properties, such as high thermal conductivity (TC), efficient electromagnetic interference (EMI) shielding ability with low electrical conductivity, superior tribological performance, reliable thermal stability and excellent mechanical properties. However, the integration of these mutually exclusive properties is still a challenge, ascribed to their different requirement on the incorporated nanofillers, composite microstructure as well as processing process. Herein, a well-designed boron nitride nanosheet (BN)/graphene nanosheet (GNP)/polyphenylene sulfide (PPS) composite with a dual-segregated structure is fabricated via high-pressure molding. Rather than homogenous mixing of the hybrid fillers, GNP is first coated on PPS particles and followed by encapsulating the conductive GNP layers with insulating BN, forming a BN shell-GNP layer-PPS core composite particles. After hot-pressing, a dual segregated structure is constructed, in which GNP and BN are distinctly separated and arranged in the interfaces of PPS, which on the one hand gives rise to high thermal conductivity, and on the other hand, the aggregated BN layer can act as an “isolation belt” to effectively reduce the electronic transmission. Impressively, high-pressure is loaded and it has a more profound effect on the EMI shielding and thermal conductive properties of PPS composites with a segregated structure than that with homogenous mixed-structure composites. Intriguingly, the synergetic enhancement effect of BN and GNP on both thermal conductive performance and EMI shielding is stimulated by high pressure. Consequently, PPS composites with 30 wt% GNP and 10 wt% BN hot-pressed under 600 MPa present the most superior comprehensive properties with a high TC of 6.4 W/m/K, outstanding EMI SE as high as 70 dB, marvelous tribological performance, reliable thermal stability and satisfactory mechanical properties, which make it promising for application in miniaturized electronic devices in complex environments.