Volume 42, Issue 6

Magnesium ion conducting eco-friendly biopolymer electrolyte based on gellan gum has been developed by solution casting technique and characterized by XRD, FTIR, DSC, AC impedance analysis and LSV. Amorphous nature of the polymer electrolyte has been confirmed by XRD analysis. FTIR analysis confirms the complex formation between gellan gum and magnesium nitrate salt. Glass transition temperature of the polymer electrolytes have been found in DSC analysis. Ionic conductivity of polymer electrolyte membrane has been analysized by AC impedance studies, polymer electrolyte 1.0 g gellan gum with 0.7 wt% Mg (NO 3 ) 2 has highest ionic conductivity 1.392 × 10 −2  S/cm at room temperature. Evan’s polarization method attributes Mg + cationic transference number as 0.342 for high conducting polymer electrolyte. The high conducting polymer membrane has electrochemical stability 3.58 V. Using this high conducting polymer electrolyte, magnesium ion battery is constructed and the battery performance was studied. The open circuit voltage is found as 1.99 V.

In this work, we analyzed the pH, temperature, and salt effects of the charged polypeptide and its size, poly- d -lysine (PDL) molecules while applying dynamic light scattering (DLS), Zeta potential, and rheology techniques to assess the most important characteristics of PDL. The experimental results showed that the structural transitions of PDL were a result of a competition between electrostatic interaction, which promotes an extended state, and the hydrophobic effect, which favors a compact state. Moreover, by exploiting the electrokinetic charge on the PDL molecules the zeta potential was determined. We tried to find an analogy between size, viscosity, and conformational changes of PDL so to serve as a guide for polypeptide aggregation in solution.

To modify polyvinylchloride membranes for carbon dioxide gas separation, six polyvinyl chloride- g -polyionic liquid ionomers such as polyvinylchloride- g -poly1-vinyl-3-hexylimidazolium bromide (PVC- g -P[VHIm][Br]), polyvinylchloride- g -poly1-vinyl-3-hexylimidazolium thiocyanate (PVC- g -P[VHIm][SCN]), polyvinylchloride- g -poly1-vinyl-3-hexylimidazolium tetrafluoroborate (PVC- g -P[VHIm][ BF 4 ]), polyvinylchloride-g-poly1-vinyl-3-octylimidazolium bromide (PVC- g -P[VOIm][Br]), polyvinylchloride- g -poly1-vinyl-3-octylimidazolium thiocyanate (PVC- g -P[VOIm][SCN]) and polyvinylchloride- g -poly1-vinyl-3-octylimidazolium tetrafluoroborate (PVC- g -P[VOIm][ BF 4 ]) were synthesized. The polyvinyl chloride- g -polyionic liquid ionomers were characterized using elemental analyzer (CHN) and Fourier transform infrared spectroscopy (FTIR) techniques. CO 2 adsorption onto these ionomers was measured by quartz crystal microbalance (QCM) and the experimental data were correlated by the sorption model. The parameters obtained imply that CO 2 adsorption has an exothermic and physisorption nature. Also, the investigations point to that the PVC- g -P[VHIm][SCN] has better performance for CO 2 separation.

A novel synergy flame retardant system of poly(ethylene terephthalate) (PET)/organic-Zn(H 2 PO 2 ) 2 /lithium containing polyhedral oligoheptyl silse-squioxane (Li-Ph-POSS) composites was prepared by the melt-blending method to improve the flame retardancy of PET. The synergistic effect of organic-Zn(H 2 PO 2 ) 2 and Li-Ph-POSS on the flame retardancy, thermal, and mechanical properties of the PET composites was investigated by the limiting oxygen index, vertical burning test, cone calorimeter, thermogravimetric analysis, differential scanning calorimeter, tensile tester, and dynamic mechanical analysis, respectively. The results show that the synergistic flame retardant effect between organic-Zn(H 2 PO 2 ) 2 and Li-Ph-POSS improves both the flame retardancy and the crystallization of PET. Moreover, the Li-Ph-POSS has a positive effect on the mechanical property of PET. This work provides a promising strategy for mitigating the fire hazard of PET using this synergy flame retardant system.

Various dimensional structured inorganic nanoparticles have different ways of improving mechanical properties of polymeric materials. However, there are limited studies on hybridization of different nanoparticles with different dimensional structures for optimal enhancement of mechanical properties of polymer matrix. Therefore, this study combined nanoparticles with 0D (barium titanate [BT]), 1D (carbon nanotubes [C]), and 2D (graphene [G] and boron nitride [BN]) to significantly promote the hardness, elastic modulus, tensile strength/modulus, heat deflection and Vicat softening temperature of polypropylene (PP) nanocomposites. The nanoparticles were surface functionalized to take care of good interfacial interaction with the PP matrix. The nanocomposites were fabricated via melt compounding techniques. Although all the developed nanocomposites showed enhanced mechanical and thermomechanical properties, the ones containing hybrid of carbon and ceramic nanoparticles with different dimensional structures showed superior responses. For instance, optimal hardness, elastic modulus, heat deflection and Vicat softening temperature of about 269.5 MPa, 2.9 GPa, 100.7 °C, and 160 °C were measured for the hybrid PP/3 wt%BNG/3 wt%BTC nanocomposite, which are about 239.4%, 77.7%, 19 °C, and 11 °C higher than that of the pure PP, respectively. The significant enhancement in the measured properties is attributed to effective mechanical interlocking and network structural hardening of the PP matrix.

To overcome the pollution to the environment with the application of flame retardants in automobiles, complete environment-friendly flame retardants have aroused wide concern. Furthermore, natural fibers have replaced artificial fibers in various fields due to their excellent performance and environmentally friendly. Thus, in this work, modified hemp fiber (HF-P) via phytic acid was obtained and used as a green flame retardant for automobile parts containing unsaturated polyester resins (UPR). The flame retardance of UPR composites were tested by thermogravimetric analysis, limiting oxygen index (LOI), and cone calorimeter test. A total of 3 wt% HF-P imparted UPR matrix excellent flame retardancy. The LOI value of UPR/HF-P-3 composites was increased from 18.9% of pure UPR to 22.1%, and the values of AHRR and THR were reduced to 401.9 kW/m 2 and 150.6 MJ/m 2 , respectively. TGA test shows that HF-P can effectively improve the carbon-forming ability of UPR composites, which provides a material basis for condensed phase flame retardancy. For mechanical properties, the incorporation of HP-F endows a better enhancement on flexural strength of UPR composite.

Insulating materials with heat dissipation are urgently required for modern electronic devices and systems. In this study, 4,4-methylene diphenyl diisocyanate was used as the coupling agent, and nano-diamond (ND) particles were grafted onto the surface of carbon fibers (CFs) to prepare CF-ND/silicone rubber (SR) composites. The ND acted as a “bridge” among CFs, which can reduce the interface thermal resistance between CFs because the dot-like ND can increase the interfacial area of CFs, making it easier to form heat-conducting networks between SR. When the content of CF-ND (1:6) was 20%, the thermal conductivity of the SR composite was 0.305 W/(m·K), 69% higher than that of pure SR. The ND between CFs can improve the dynamic mechanical properties by acting as a crack pinhole. In addition, the CF-ND/SR composites also exhibited excellent thermal stability. This work has enormous potential for advanced electronic devices.

The application of plastics in the food and agriculture industries as packaging materials is immense. However, the damage caused to the environment by accumulating such non-biodegradable plastics has led to the development of better alternatives. This has caused an increase in the use of synthetic polymers and proteins for the production of biodegradable films as an alternative to packaging plastics. In this study, a novel approach for the fabrication of homogenous and biodegradable films using PVA/galactomannan/gelatin (PGG) composite has been developed. The in-situ synthesis of silver nanoparticles (Ag NPs) was attained by hydrothermal reduction. The formation of Ag NPs within the PGG composite imparted substantial antimicrobial properties to the films. The optical properties of Ag NPs-PGG composite and its films were characterized using UV–vis spectrophotometry, Fourier transfer infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The Ag NPs-PGG films were evaluated for their physical and mechanical properties and cytotoxicity and were found to have high tensile strength, flexibility and biocompatibility. The films were also subjected to an in-door soil burial test for 15 days and were observed to decompose rapidly. The developed Ag NPs-PGG composite films with bactericidal properties have potential use in food packaging and various biomedical applications.

The physical properties of plastic products, such as local strength, wear resistance and electrical properties, can be improved by adding embedded parts in the appropriate position of the products, and the precision of plastic parts can also be improved. However, due to the addition of inserts, the flow and shrinkage around inserts will be affected. Compared with traditional injection molding products, the quality is difficult to predict. To solve this problem, the injection molded parts with inserts (electrostatic test box) was used as an example, according to the product structure, three objectives of volume shrinkage, warpage in the X direction, and warpage in the Z direction were optimized. A generalized regression neural network (GRNN) model was established with molding parameters as input and quality objectives as output. Improved fruit fly optimization algorithm (IFOA) was proposed to select the optimal smoothing parameters dynamically. Through the prediction of samples, the experimental results show that the model is superior to two comparative models. Non-dominated sorting genetic algorithm (NSGA-II) was used to solve the model, and the Pareto-optimal front was obtained. The entropy TOPSIS method was used to evaluate the Pareto-optimal front, and the optimal solution was obtained. The results show that IFOA-GRNN-NSGA is a reliable multi-objective optimization method.