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3D printing technology has emerged as a high value-added industry with high efficiency that has dramatically broken away from the existing material and manufacturing industry’s human-based production system. These technologies, ranging from small parts to large structures, are rapidly developing due to the challenge of various filament materials, whereas there are significant concerns about waste filler materials, and complimentary research is needed to improve them. Polylactic acid (PLA), the representative polymer of 3D printing, contributes to minimizing environmental risks. However, although thermoplastic PLA has excellent reversible properties for heat in terms of sustainable resources, it is degraded as a low value-added material afterward. Therefore, in this study, the effect of repetitive recycling on the mechanical and thermal properties of PLA filaments was analyzed to verify and re-evaluate PLA as a renewable resource. As a result, recycled PLA has decreased tensile and flexural strength by up to 69% and 53%, respectively, compared to initial neat PLA with the increase of the number of repetitive recycling, and this demonstrates the change in the thermal properties of recycled PLA.

Silicene sheet is prepared by atomistic multiscale modeling using molecular dynamics (MD) simulations to evaluate thermal properties of silicene at different temperatures and variable sample sizes. In this paper, by MD simulation study, we have estimated coefficient of linear and surface expansion between a temperature range from 318 K to 398 K, specific heat at constant volume and pressure, melting point, heat of fusion and thermal conductivity of silicene at different sample sizes by both equilibrium molecular dynamics (EMD) and non-equilibrium molecular dynamics (NEMD) approaches. The presented multiscale modeling approaches could guide experimental studies to design silicene sheet with required thermal properties for operation under specific conditions.

In order to supply high quality silver source to photothermographic material based on silver carboxylate, silver plamitate was prepared by chemical deposition method using palmitic acid, sodium hydroxide, silver nitrate as raw materials and PVP as surfactant in water system. The morphology, crystal structure and thermal properties of silver palmitate were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and Thermogravimetry (TG). The results indicate that silver palmitate has good purity and well-defined layer structure with triclinic phase. The diameter of fiber-like silver palmitate is about 200 nm, which shows excellent dispersion properties. DSC curves demonstrate that silver palmitate has seven endothermic peaks below 240°C. Five endothermic peaks below 190°C assign to different phase transitions. Silver palmitate decomposed step-by-step at 204.1, 223.6, and 253.9°C.

The electronic structure, mechanical property and thermal expansion of yttrium oxysulfide are calculated from first-principles using the theory of density functional. The calculated cohesive energy indicates its thermodynamic stable nature. From bond structure, the calculated bandgap is obtained as 2.7 eV; and strong covalent bonds exist between Y and O atoms intra 2D [Y–O] layer in material, while relatively weak covalent bonds also exist inter 2D [Y–O] layer and S atoms. From simulation, it is found that the bulk modulus is about 119.4 GPa for the elastic constants, and the bulk modulus shows weak anisotropy because the surface contours of them are close to a spherical shape. The calculated B/G clearly implies its ductile nature, and the Y₂O₂S phase can also be compressed easily. The temperature dependence of thermal expansions is mainly caused by the restoration of thermal energy due to lattice excitations at low temperature. When the temperature is very high, the thermal expansion coefficient increases linearly with temperature increasing. Meanwhile, the heat capacities are also calculated and discussed by thermal expansion and elasticity.

The thermal and degradable properties of carbodiimide (EDC) or glutaraldehyde (GTA) cross-linked gelatin membranes have been investigated in order to evaluate the effects of different concentrations of two kinds of cross-linking reagent on the stability of membranes. In the thermogram recorded from a gelatin membrane cross-linked with EDC solution, the endothermic peak of 0.8% EDC cross-linking gelatin was centered at about 61°C that was higher than other samples treated with EDC solutions. Denaturation temperature (Td) of gelatin samples increased on increasing EDC concentration (0.2% to 0.8%), in agreement with the simultaneous increased of the extent of cross-linking. But increasing GTA concentration from 0.05% to 0.6%, the Td values of gelatin samples were decreased from 66.2°C to 56.3°C . In addition, two endothermic peaks were observed in 0.4% and 0.6% GTA cross-linking groups because of the GTA concentration was too high to complete cross-linking reaction. Therefore, partial of gelatin membrane was cross-linked completely but others were not. In the thermogravimetric analysis, the proportion of cracking endothermic peak of 0.6% GTA cross-linking gelatin (g15G0.6) was higher than the peak of 0.6% EDC cross-linking gelatin (g15C0.6). Therefore, g15G0.6 cracked to smaller molecules has to absorb more calorific capacity than g15C0.6. The increase in the strength of covalent binding on increasing the proportion of endothermic peak was evident. The results of degradable rate were in agreement with the lower concentration of cross-linked reagent the faster degraded rate of gelatin membrane. The MTT assay showed that 15% gelatin cross-linked by 0.8% EDC has the least cytotoxicity, and cell activity of this group was similar to control group (blank dish). As the concentration of GTA in gelatin membranes was down to 0.05% or 0.1% the cell viability was returned to approach the value of control group.

The Vac-veova latex coatings was a good type of film-forming material in intumescent fire retardant coatings, it had good properties in high thermal stability, so it was very suitable to serve as the film-forming material of IFR coatings for structural steel to improve its fire resistance. According to the research results, the different ratio between each component had obvious difference for fire prevention effect, in the APP/PER/MEL/EG for IFR coatings, the best ratio of APP/PER/MEL/EG was 5.25:2:2:1.25, and the best content ratio between IFR and Vac-veova latex emulsion was 35/25. According to the chosen component ratio in IFR, its intumescent ratio could reach 22.68%, the fire-resistant time reached 149s. After burnt out, the residual weight reached 47.12% at 75kW/m².

Unvulcanized polar graft-modified rubbers, including maleic anhydride grafted ethylene propylene diene monomer (MAH-g-EPDM) and 49% methyl methacrylate grafted natural rubber (MMA-g-NR, i.e. MG49 rubber), were empolyed to toughen polystyrene (PS). The results showed that Charpy impact strength of the unnotched PS specimens at room temperature was improved by addition of the graft-modified rubbers. Moreover, Charpy impact strength of the composite increased with increasing content of polar graft-modified rubbers in this study, and the incorporation of MAH-g-EPDM enhanced impact strength of PS more markedly than that of MG49 did. The result of thermogravimetric analysis (TGA) indicated that the addition of MAH-g-EPDM improved the thermal stability of PS, while the incorporation of MG49 reduced it. The result of thermal mechanical analysis (TMA) indicated that the glass transition temperatures of their corresponding PS-based blends increased with the addition of either MAH-g-EPDM or MG49. The glass transition temperatures of PS-based blends increased with increasing polar graft-modified rubbers content. This may be due to the incorporation of the polar grafts. This work may also provide some information for oil-resistant modification of PS due to the polar groups grafted onto the backbone of rubbers.

3D printing technology has emerged as a high value-added industry with high efficiency that has dramatically broken away from the existing material and manufacturing industry’s human-based production system. These technologies, ranging from small parts to large structures, are rapidly developing due to the challenge of various filament materials, whereas there are significant concerns about waste filler materials, and complimentary research is needed to improve them. Polylactic acid (PLA), the representative polymer of 3D printing, contributes to minimizing environmental risks. However, although thermoplastic PLA has excellent reversible properties for heat in terms of sustainable resources, it is degraded as a low value-added material afterward. Therefore, in this study, the effect of repetitive recycling on the mechanical and thermal properties of PLA filaments was analyzed to verify and re-evaluate PLA as a renewable resource. As a result, recycled PLA has decreased tensile and flexural strength by up to 69% and 53%, respectively, compared to initial neat PLA with the increase of the number of repetitive recycling, and this demonstrates the change in the thermal properties of recycled PLA.