The study involves the preparation of foam concrete using fly ash modified by silane coupling agents, and investigates the effects of the amount of modified fly ash added on the waterproof and thermal insulation performance of the foam concrete. The results showed that when the mass fraction of silane coupling agent modified fly ash was 1.5%, the dry density of foam concrete decreased by 5.85%, the porosity increased by 3.67%, the water absorption decreased by 23.62%, and the thermal conductivity reached the lowest, 0.029 W/(m·K). Therefore, the proper addition of modified fly ash can effectively improve the thermal insulation performance and waterproof performance of foam concrete, but lead to a small loss of the mechanical properties of foam concrete. The 1.5% addition mass fraction of silane coupling agent can improve the thermal insulation performance and try to maintain the compressive strength of foam concrete.

Phenolic resin is modified to improve its defect of poor acid resistance in high temperature environment. Under the condition of alkaline catalyst, furfural, phenol and formaldehyde were subjected to co-polycondensation reaction to produce thermosetting furfural-phenol-formaldehyde co-polymerization resin (FPF). P-toluenesulfonic acid was selected as the curing agent for curing the synthesized FPF, and the FPF curing compounds were prepared. The effects of synthesis conditions on FPF viscosity, solid content, and high-temperature and strong-acid resistance of FPF cured products were investigated. The results showed that when the reaction temperature was 95 ℃, the amount of catalyst was 6% of the mass of phenol, and the replacement rate of furfural to formaldehyde was 15%, the viscosity of FPF was 1 200 mPa∙s, and the solid content was 87.7%. Thermal weight loss test of FPF cured material showed that its maximum decomposition rate was 2.883%/min in the rapid decomposition stage, which was 33.1% lower than the decomposition rate of conventional phenolic resin (PF). The mass retention of FPF cures treated with high temperature and strong acid environment was 96.56%, which was 6.44% higher compared to the mass retention of PF cures. Furfural as a substitute for part of the formaldehyde to modify phenolic resins has improved acid resistance and thermal stability, and the modified phenolic resins can be applied in environments with strong acids and high temperatures.

Polyvinyl chloride (PVC), the most widely used halogen-containing plastic, presents challenges in terms of the emission of dangerous gases like chlorinated hydrocarbons and dioxins during the recycling process, as well as damage to equipment and pipelines. Pyrolysis technology has the potential to both dechlorinate PVC-containing waste plastics for safe disposal and transform waste into valuable chemicals and fuels, thereby enhancing product yield and quality. Pyrolysis technology is one of the promising industrial technologies for waste plastic treatment. The paper focuses on the research progress of pyrolysis dechlorination technology at home and abroad. It comprehensively sorts out the dechlorination mechanisms of different technologies, including stepwise pyrolysis, adsorption pyrolysis, catalytic pyrolysis, co-pyrolysis, and combined pyrolysis. Additionally, it summarises various factors that affect the dechlorination effect of pyrolysis, such as the types and modes of action of additives, placement modes, and types of admixtures. It analyses the advantages and disadvantages of each technology and its industrial application prospects to provide a reference for the industrialisation of dechlorination and recycling of waste plastics.

Increasing or broadening the thermal conductivity path by constructing a thermal conductivity network is one of the common ways to prepare high thermal conductivity composites. The interlacing or orientation of copper nanowires with one-dimensional structure can be connected into a network structure, which greatly improves the heat dissipation performance of composites. In this paper, three preparation methods of copper nanowires were introduced: Template electrodeposition method, liquid phase reduction method, and direct impregnation method. The vertically oriented and network structure copper nanowires were prepared by different methods with high thermal conductivity, which can significantly improve the thermal conductivity of the materials as thermal conductive fillers. Six preparation methods of copper nanowire composites were introduced: Physical blending method, freeze-drying method, magnetic field orientation method, hot pressing method, solution casting method, and vacuum filtration method. The principles of each method wereintroduced, the influencing factors of thermal conductivity of various composite molding methods were analyzed, the different preparation methods were summarized, and the thermal conductivity properties of different preparation methods were summarized. Finally, the thermally conductive composites filled with copper nanowires were summarized and prospected.

Polyglycolic acid (PGA) has excellent degradation performance and mechanical strength, but its poor toughness limits its further application to some extent. In order to fully utilize the excellent degradation performance and mechanical strength of PGA, and to improve its toughness and processing performance, a copolymer of poly(glycolide-co-caprolactone) copolyesters (PGACL) was prepared through the ring-opening polymerization of glycolide and ε-caprolactone, starting from the molecular chain structure. The properties of PGACL were further regulated by the chain extender 1,4-butanediol glycidyl ether (BDE). By determining the optimal amount of initiator, the effects of the content of glycolide and chain extender on the mechanical properties, thermal properties, and degradation performance of copolyesters were studied. The results showed that increasing the glycolide content significantly enhanced the thermal properties, crystallinity, and mechanical strength of the copolyester. The introduction of the chain extender greatly improved the toughness of PGACL, while the synthesized PGACL copolymer maintained good degradability.

Polyether polyols with molecular weights of 12 000 g/mol and 18 000 g/mol were synthesized with propylene glycol as starting agent and bimetallic cyanide complex (DMC) as catalyst. The structure of the product was characterized by Fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance spectroscopy (¹H-NMR) and gel permeation chromatography (GPC). Ultra high molecular weight polyether polyols have the characteristics of narrow molecular weight distribution and low unsaturation. The effects of initiator moisture content, feed rate, polymerization temperature and stirring speed on polymerization activity and product indexes were discussed. When the water content of propylene glycol initiator is \le 0.06%, the PO feed rate is 220~250 g/h, the polymerization temperature is controlled between 130~135 ℃, and the catalyst concentration is 30 mg/kg, the product quality can be ensured. Silane modified polyether resin (MS resin) was synthesized from the prepared ultra high molecular weight polyether polyol and MS glue was prepared. The results show that MS resin has moderate viscosity and excellent properties.

Carbon-based materials have large specific surface area, well-developed pores, and a large number of oxygen-containing functional groups on the surface, which have excellent mechanical properties. Introducing carbon-based materials into the hydrogel system can increase adsorption sites, improve mechanical properties, enrich network structure, realize complementary advantages, and overcome performance defects, which is the main idea for developing high-performance hydrogel adsorbents. In this paper, the structural characteristics of different types of carbon based composite hydrogels were summarized, and the mechanism of carbon based materials to enhance the performance of hydrogels was emphatically introduced. The preparation methods of composite hydrogels and their applications in the field of water purification were reviewed. The prospects, limitations and future research potential of carbon based composite hydrogels adsorbents were analyzed.

To alleviate the problem of white pollution caused by non-biodegradable plastic waste, the development of biodegradable plastics as a partial substitute for non-biodegradable plastics is a hot research topic. The article provides an overview of biodegradable plastics, introduces the characteristics and research progress of petrochemical-based biodegradable plastics and bio-based biodegradable plastics. It also summarizes their applications in medicine and healthcare, packaging, and agricultural mulch films. It is pointed out that the current development of biodegradable plastics is significantly constrained by limitations in cost and performance, such as barrier properties, mechanical properties, and thermal resistance. However, the optimization of processing techniques and selecting suitable additives can enhance the overall performance of biodegradable plastics. Future research should ensure the performance of biodegradable materials and reduce their production costs.

After altering ground tire rubber(GTR) with formic acid and hydrogen peroxide, the epoxidation product (EGTR) was produced. The poly(lactic acid) (PLA)/EGTR blends were then made using the melt blending method, and their micro-morphology, crystalline behavior, and mechanical properties were all carefully examined. The results showed that the carbon-carbon double bond on the GTR molecular chain was successfully oxidized to an epoxy group by formic acid and hydrogen peroxide. The EGTR particles were evenly distributed throughout the PLA matrix, demonstrating good compatibility between the two phases. Furthermore, low levels of EGTR promote PLA crystallization, while high levels of EGTR inhibit PLA crystallization. The PLA/5% EGTR blends had the highest crystallinity of 11.1%, which was 4.8 times higher than that of pure PLA. The blends tensile strength declined as the EGTR content increased, while the impact strength and elongation at break showed a tendency of first increasing and then decreasing. When 10% EGTR was added, the blends had the maximum elongation at break and impact strength, with good toughening effect and tensile strength, showing the best overall mechanical properties. The study provides a basis and technical foundation for modifying PLA with GTR as a toughening material and promotes the recycling of waste rubber.

A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for the simultaneous determination of the specific migration amounts of di(2-ethylhexyl) phthalate (DEHP), di(2-ethylhexyl) isophthalate (dioctyl isophthalate, DOIP) and di(2-ethylhexyl) terephthalate (dioctyl terephthal, DOTP) in plastic food contact material and products. 1.00 mL of the well-mixed 10% ethanol, 3% acetic acid, 4% acetic acid, 20% ethanol and 50% ethanol or isooctane soaking solution sample of plastic food contact material products was accurately pipetted into a 10 mL volumetric flask, the volumetric flask was made up to the mark with isopropanol and mixed well, and then the solution of the volumetric flask was passed through a needle filter membrane into an injection vial for testing. Using methanol and 0.1% formic acid water as mobile phases, the baseline separations of DEHP, DOIP and DOTP were achieved in a C₁₈ column within 16 minutes, and the tandem mass spectrometry was operated in ESI and MRM modes. In the food simulant soaking solutions of 10% ethanol, 4% acetic acid, 50% ethanol or isooctane of polypropylene (PP) plastic cups, the recovery rates of DEHP, DOIP and DOTP at three spiking levels were ranged from 83.8% to 113.0%, with relative standard deviations (RSDs) from 1.4% to 8.3%. The linearities of DEHP, DOIP and DOTP were good with R≥0.999 4 in the concentration range of 0.010~0.200, 0.100~2.000, 0.500~10.000 µg/L respectively, and the quantitative limits of DEHP, DOIP and DOTP were 0.020, 0.300, 1.300 mg/kg respectively. The method is fast, simple and accurate, and the quantitative limits also meet the requirements of standards and regulations. It can effectively avoid the confusing errors in detection results caused by incomplete chromatographic separation of isomers with different limits and similar mass spectrometry confirmation ion pairs. It has been applied in the detection of DEHP, DOIP and DOTP in actual samples.

In order to prepare high-performance high damping composites, high damping petroleum resin C5/CIIR composites were prepared by blending petroleum resin C5 with chlorinated butyl rubber (CIIR), and the mechanical and damping properties of the composites were studied. The results show that with the increase of C5 content, the tensile strength of the composites gradually decreases, while the elongation at break gradually increases, and the compression permanent deformation continuously increases. Moreover, the content of petroleum resin C5 in high damping rubber composites should not exceed 40%. The addition of petroleum resin C5 improves the damping performance of composites. When the content of petroleum resin C5 accounts for 30% of the CIIR mass, a high damping petroleum resin C5/CIIR composites with good comprehensive performance can be prepared. Compared with the material without petroleum resin C5, although the tensile strength of the composites is reduced and the compression permanent deformation is increased, it still meets the relevant standard requirements. The elongation at break of composite materials is increased by 54.6%, and the enclosed area of loss factor-temperature curve (A _T) is increased by 14.0%.

Hydrophobic nano-ZnO(s) and pure nano-ZnO(u) were melt blended with polylactic acid (PLA) through a twin-screw extruder to obtain PLA/ZnO nanocomposites. The effects of surface activity and addition amount of nano-ZnO on the properties of PLA/ZnO nanocomposites were investigated. The results show that the comprehensive properties of PLA/ZnO(s) nanocomposites prepared by surface treated nano-ZnO(s) are better than those of PLA/ZnO(u) nanocomposites. Nano-ZnO has a catalytic effect on the thermal degradation of PLA molecular chains under high temperature conditions. When the amount of nano-ZnO is continuously increased, the crystallization ability and mechanical properties of PLA/ZnO(s) and PLA/ZnO(u) nanocomposites are continuously decreased. The surface-treated nano-ZnO(s) will inhibit the depolymerization reaction of PLA molecular chain and the occurrence of intermolecular transesterification reaction at high temperature. When the amount of nano-ZnO is the same, PLA/ZnO(s) nanocomposites have higher crystallization ability and better mechanical properties. When the addition amount of nano-ZnO is 1 phr, the impact strength of PLA/ZnO(s)-1 nanocomposite reaches 5 533.8 J/m² and the tensile strength reaches 64.0 MPa, which are higher than the impact strength (4 711.0 J/m²) and tensile strength (58.1 MPa) of PLA/ZnO(u)-1 nanocomposite.

The high-dose ultraviolet (UV) aging test of high density polyethylene (HDPE) composites modified by different contents of compound light stabilizer was tested by UV aging test chamber with UV irradiation intensity of 500 W/m². Fourier transform infrared spectroscopy (FTIR) test showed that the carbonyl index was positively correlated with the aging degree of HDPE. The aging rate of HDPE was significantly reduced by the addition of ultraviolet additives. The molecular weight of modified HDPE was analyzed by rotating rheology, which could found that the crosslinking reaction rate of HDPE was inhibited more with the increase of ultraviolet additives in the early aging period. Combined with the above analysis and mechanical test results, it was found that when the modified HDPE material needed to withstand the total ultraviolet irradiation of 200 kWh/m², the modified HDPE material could maintain good properties by only adding 1.2 phr compound light stabilizer in 100 phr matrix. The retention rates of elongation at break, tensile strength and notch impact strength were 57.7%, 63.8% and 105.0%, respectively.

To investigate the synergistic effects during the pyrolysis process of waste plastics in municipal solid waste, a TG-FTIR-MS coupling analysis method was utilized to systematically study the thermogravimetric behavior, functional group changes, and gaseous product characteristics during the pyrolysis of polyvinyl chloride (PVC), polystyrene (PS), and their co-pyrolysis. On this basis, the differences in pyrolysis characteristics between pure PVC and PVC/PS mixtures were analyzed, along with the reasons for these differences. The results showed that the main gaseous products of PVC pyrolysis were hydrogen chloride (HCl) and small amounts of chlorinated hydrocarbons. In the PS pyrolysis process, the main reactions were depolymerization into styrene monomers and a small amount of random chain scission. There was a strong synergistic effect during the co-pyrolysis of PVC and PS, which could be divided into two stages. In the first stage (235~326 ℃), the primary products were HCl and chlorinated hydrocarbons, while in the second stage (326~516 ℃), the main products were alkanes, olefins, and small amounts of aromatic compounds. Therefore, dechlorination treatment could be carried out within the temperature range of 235~326 ℃. Compared with the pyrolysis of pure PVC, chlorine release was inhibited during the co-pyrolysis of PVC and PS, resulting in reduced HCl production and increased chlorine content in the solid products. The findings can provide support for the development of municipal solid waste pyrolysis technology.

A new spectroscopic method for the determination of microplastics based on the principle of dye-gain absorption has the advantages of simplicity, rapidity, high sensitivity and selective detection of micro-nano fragments. Different particle sizes and types of plastics were used as test materials, and the results showed good gain absorbance. The applicability of the method showed that for the microplastic particles and fiber mixtures with the particles larger than 1 μm, the concentration could be determined by staining, centrifugation, and then taking a quantitative solution on a hemocyte counting plate by microfluorescence counting. For the nanoplastics with the particles lower than 1 μm, the spectrophotometric method can be employed for measurement by utilizing the linear relationship between the concentration of the suspended phase after staining and its absorbance. The method was applied to actual water samples from a wastewater treatment plant, and the results showed that the spiked recoveries of the actual samples ranged from 99.00% to 107.00%, and the detection limit of the method was up to 1.53 mg/L.The present study will provide a convenient method for the quantitative detection of micro-nano plastics in the environment, which has good applicability and wide application prospects.

In order to reduce the environmental pollution caused by plastic waste, research is being conducted on the photocatalytic degradation and recycling of plastics, utilizing the degradation mechanism of solar photoinitiation and photocatalysis to convert plastics into water and carbon dioxide, or further into hydrogen fuel and high-value chemicals. The article introduces the effects of catalyst characteristics, plastics, and degradation conditions on photocatalytic degradation, summarizes the applications of different types of inorganic metal, non-metal materials, and organic-inorganic composite photocatalysts in photocatalytic degradation and recycling, and aims to improve photocatalytic efficiency through catalyst modification and synergistic effects with electrocatalysis, thermocatalysis, and biocatalysis. The article points out the problems in the pre-treatment and post-treatment of photocatalytic degradation plastic recycling technology, providing a reliable basis and research direction for the recycling and treatment of waste plastics.

In this study, the structure and properties of two surface-roughened films of biaxially oriented polypropylene (BOPP) before and after oil immersion were investigated. The roughening morphology of BOPP was characterized by optical microscopy, the crystal structure and crystallographic behavior were inspected by DSC and WAXD, and the orientation structure was evaluated by polarized infrared technology. The tensile mechanics, thermal oxidation stability and breakdown strength of the films were tested. The results show that the crystal structure of BOPP films prepared by two kinds of polypropylene with different chain characteristics does not change significantly before and after oil immersion. The orientation parameters θ _j and f_j suggest that the orientation of the amorphous chains is decreased by oil immersion. In addition, the oil immersion improved the breakdown strength of the film. For example, the breakdown strengths of the high tacticity and narrow distribution films are 737 V/μm (before oil immersion) and 863 V/μm (after oil immersion). These results indicate that soaking in the insulating oil medium for a long time, the orientation relaxation in the amorphous region can eliminate the structural defects caused by internal stress and increase the breakdown strength of BOPP films.

In order to investigate the effect of the polyolefin elastomer (POE) chain structure difference on the structure and properties of polypropylene/polyolefin elastomer (PP/POE) composites, POE with different chain structure, talc masterbatch (Talc) and PP were melt blended to prepare PP/POE composites. The structure and properties of PP composites were characterized by a melt flow rate tester, an electronic universal tester, a cantilever impact tester, a thermogravimetric analyzer (TG), a differential scanning calorimeter (DSC) and a field emission scanning electron microscope (FESEM). The results show that compared with an ethylene-1-butene copolymer (POE-C4), an ethylene-1-octene copolymer (POE-C8) not only maintains the tensile strength of PP/POE composites, but also improves the toughness of the composites. The difference in POE chain structure has no obvious effect on the thermal stability of PP/POE composites.

The non-isothermal crystallization behavior and kinetics of PBAT, PBAT/talc powder composites was studied by differential scanning calorimentry combined with the Avrami equation. The modified Avrami theories of Jeziorny and Mo's method were used to analyze the data. The activation energy of non-isothermal crystallization of PBAT and PBAT/talc powder composites were calculated by Kissinger's method. The results showed that proper talc powder had the effect of heterogeneous nucleation in crystallization, increased the crystallization temperature and crystallization rate of PBAT, and decreased the grain size. When the mass fraction of talc powder were 20%, the crystallization rate and absolute value of non-isothermal crystallization activation energy reached the highest value. However, when the talc content is too high, the melt viscosity of the composites increases significantly, the movement of the PBAT molecular chain is blocked, and the speed of regular and orderly arrangement decreases, resulting in a decrease in the crystallization rate and the absolute value of non-isothermal crystallization activation energy.

Polybutylene adipate-terephthalate/thermoplastic starch/organic montmorillonite (PBAT/TPS/OMMT) biodegradable materials have attracted wide attention in recent years. However, the conventional twin-screw processing technique leads to material degradation and makes it difficult to achieve good stripping of OMMT. In order to improve its mechanical properties, PBAT was chain expansion modified by ADR-4468, and PBAT/TPS/OMMT containing different contents of modified PBAT (A-PBAT) were prepared by melt extrusion using a perturbation ring dual-speed twin-screw extruder, and the effects of different contents of A-PBAT on the microstructure, rheological properties, compatibility, water absorption and mechanical properties of the composites were analyzed. The results showed that the chain extender effectively improved the mechanical properties of PBAT, and the dual-speed twin-screw could strip OMMT well and make TPS uniformly dispersed and distributed in PBAT. With the increase of A-PBAT content, TPS transforms from continuous phase to dispersed phase, the water absorption of the composite material gradually decreases, and the tensile strength gradually increases, reaching its maximum at a mass fraction of 60% A-PBAT, with a slight decrease in elongation at break. 20% A-PBAT can effectively improve the compatibility between TPS and PBAT.

Light curing 3D printing technology has become an emerging technology in the manufacturing industry because of its high precision, rapid prototyping, and complex parts can be formed. Photosensitive resin is the main consumable of light curing 3D printing technology, and its mechanical properties, heat resistance, precision and strength are not ideal enough to meet the needs of industrial production. In order to obtain the photosensitive resin with high mechanical strength and function, it must be modified. In this paper, the modification of photosensitive resin for photocuring 3D printing is introduced. Starting with the principle of SLA photocuring rapid prototyping technology, the various components of photosensitive resin are introduced, and the modification of photosensitive resin is shown from the two aspects of reaction type and addition type. Finally, the development trend of photosensitive resin is prospected. It is pointed out that in the future, on the basis of perfecting the existing photosensitive resin materials, more new materials for 3D printing will be developed, resin formula will be expanded, and more in-depth research will be carried out on the modification of photosensitive resins, so as to develop more high-performance, higher-strength, and greener resin systems.

Polypropylene (PP) is a widely used material with excellent properties. The mechanical strength, thermal stability, wettability, and anti-aging properties of PP can be further improved, especially for secondary recycled PP. Therefore, the study aimed to improve the properties of PP by waste PP and preparing talc-filled PP blends via a simple melt plasticization and re-cooling process. Through the addition of talc, hydrogen bonds were formed between the —OH groups in talc and the —CH₃ groups on the PP carbon chain, resulting in a significant improvement in mechanical properties compared to virgin PP. The addition of 10% talc increased the fracture energy of the blends by nearly 142%. Therefore, the addition of talc in the secondary recycling of PP can effectively improve the performance of PP blends and enhance their sustainability in practical applications.

In this experiment, water soluble polyester (WSPET) was synthesized by two-step esterification with terephthalic acid (PTA), isophthalic acid (IPA), sodium phthalic acid-5-sulfonate (5-SSIPA), ethylene glycol (EG) and dihydroxymethyl propionic acid (DMPA) as raw materials, tetrabutyl titanate as catalyst. BOPET/WSPET composite membrane was prepared by emulsion crosslinking with hexa(methoxymethyl) melamine (HMMM) as crosslinking agent by the coating method. The effects of different amounts of 5-SSIPA and DMPA on the contact angle, thermal properties, boiling resistance, optical properties and physical properties of the samples were investigated. The result shows that with the increase of the amount of 5-SSIPA, the hydrophilicity of the water-soluble polyester increases, the glass transition temperature increases, and the boiling resistance decreases. With the increase of the amount of DMPA, the hydrophilicity of the water-soluble polyester is enhanced, the boiling resistance is enhanced, and the pencil hardness and adhesion of the composite membrane are significantly improved, but the flexibility is reduced. When the addition amount of 5-SSIPA is 50% (relative to IPA mole ratio) and the addition amount of DMPA is 250% (relative to IPA mole ratio), the comprehensive performance of the sample is the best.

Super absorbent resins have excellent water absorption and water retention properties, but they are difficult to be degraded by water absorption and swelling, which may cause pollution to the ecological environment, leading to a certain limitation of their application. The super absorbent resin synthesized with cellulose as graft skeleton has excellent degradability. This paper introduces the research progress, advantages, and disadvantages of the synthesis methods of cellulose-based super absorbent resin such as ⁶⁰Co-γ ray initiation, ultrasonic initiation, solution polymerization, and emulsion suspension polymerization. The research progress of cellulose-based derivatives carboxymethyl cellulose and hydroxypropyl methyl cellulose super absorbent resin in recent years is described in detail, and the application prospects of cellulose-based super absorbent resin in agriculture, sanitary products, medicine, and heavy metal adsorption are analyzed and prospected.

PBAT is a popular biodegradable plastic, which has good ductility and flexibility, but the strength of PBAT is not high, which leads to the limitation of its application. In order to improve the strength of PBAT, it is necessary to modify it. In this paper, the research progress of PBAT modification was reviewed from the aspects of blending and polymerization. The melt blending modification of PBAT with biodegradable polymers, inorganic particles, and natural polymers, and the polymerization modification of PBAT were summarized. In the future, the compatibility between the modified filler and the matrix should be further improved in the blending modification. The polymerization modification should be designed through the polymer chain structure to control the proportion and distribution of rigid and flexible groups and the topology of the polymer chain, so as to improve the strength of PBAT. The research provides ideas for preparing high strength PBAT composites.

Polylactic acid (PLA), as a polymer with good biodegradability and biocompatibility, has shown extensive application potential in many fields such as aerospace, biomedical, food packaging, and so on. However, PLA also has some application limitations, such as high brittleness, low strength, and slow degradation rate. In order to overcome these limitations and further improve the performance of PLA, researchers have proposed various modification strategies, including adding nanomaterials for modification, adding biodegradable materials for modification, adding fiber materials for modification, crystallinity modification, compatibilization modification, functionalization modification, and copolymer grafting modification. The article briefly introduces the structure and two synthesis principles of polylactic acid (PLA) composite materials, and systematically reviews the principles of these modification methods and the effects of modified composite materials on mechanical properties and crystallinity. Finally, the future research directions of PLA composite material modification technology are prospected.

Polyethylene terephthalate-1,4-cyclohexane dimethyl ester (PETG) can be used as a preferred polymer material for 3D printing due to its excellent properties, which has been favored by scholars. In this paper, the printing process of PETG was studied, and it was found that the printing direction, printing thickness, printing temperature, printing speed and filling density, and other process parameters would have a significant impact on the performance of the product. The modification of 3D printed PETG material was studied by blending modification methods such as fiber, polymer, and graphene to improve the fatigue resistance, mechanical and thermal properties of the material. The application research of 3D printing PETG in biomedicine, machining and marine fields as well as the feasibility study of recycling were reviewed in detail. Finally, the development prospect of 3D printing PETG in the future was predicted. It is expected to provide guidance for the industrial application of 3D printed PETG materials.

In order to design a set of injection molds for the housing of electrical instruments that can realize automatic demoulding, Moldflow analysis technology is used to determine the optimal gate position. With the goal of reducing the warpage deformation of plastic parts, the best cooling scheme was determined through a comparative analysis. In order to realize the automatic separation of the gating system, the three-plate mold base is selected for mold opening. Combined with the optimization results, the gating system and cooling system of the mold were designed using UG NX software. According to the structural characteristics of the outer side hole of the plastic part, the slider is placed on the moving die side and the fixed die side in two forms, and the outer core pulling action is completed with the bent pin respectively. There is an inverted buckle structure on the back of the plastic part, and the inclined top structure is used for inner core pulling. The actual production verification shows that the mold structure design is reasonable, the purpose of automatic demoulding is realized, and the plastic parts have better molding quality and can meet the production requirements.

The prepolymer was synthesized using hydroxyl-terminated polybutadiene (HTPB), poly(butylene adipate) (PBA2000), isophorone diisocyanate (IPDI), 1,4-butanediol (BDO), ethylenediamine (EDA), and 2,2-dimethylolpropionic acid (DMPA) as the main raw materials. The prepolymer was then neutralized with triethylamine (TEA) to obtain HTPB-modified waterborne polyurethane. In the prepolymerization process, the molar ratio of isocyanate group (—NCO) and hydroxyl group (—OH) in the polyol was fixed 2.3∶1, the content of DMPA was 3.8%, and the waterborne polyurethane emulsion with a solid content of 38% (measured value) was finally prepared by adjusting the proportion of HTPB in the polyol. The effects of HTPB content in polyols on the particle size of emulsion, storage stability of emulsion, water resistance, mechanical properties, thermal stability were studied. The results show that with the gradual increase of the proportion of HTPB in polyols, the average particle size of waterborne polyurethane emulsion also increases, the stability gradually decreases, the glass transition temperature decreases first and then increases, and the lowest glass transition temperature can reach -46.84 ℃. The water absorption of the produced polyurethane films first increases and then decreases, while the water resistance first decreases and then increases, and the elongation at break and low-temperature flexibility both increase with the increase of the proportion of HTPB in the polyol.

Thermosetting materials are widely used due to their excellent performance, but their difficulty in reshaping leads to resource waste and environmental pollution. By introducing the dynamic covalent bond into the cross-linking network of polymers, vitrimers with thermosetting properties and recyclable properties are prepared. In the article, the synthesis characteristics of different covalent bond exchange types of vitrimers are summarized, and the reaction mechanism, advantages and disadvantages of transesterification, disulfide exchange and imine exchange are emphasized. According to the research status of vitrimers, the application prospects in the fields of self-healing and weldability are analyzed. Finally, according to the current market demand and material properties, the future development prospects of vitrimers are prospected.

Polyphenylene oxide (PPO) composites were prepared by surface modification of carbon fibers with polydopamine(PDA). The modified carbon fibers were used as fillers to investigate the effects of different filler ratios on the mechanical and friction properties of the composites. The results show that the mechanical properties and wear resistance of PPO composites are improved by adding PDA modified carbon fiber. When the amount of modified carbon fiber added is 4%, the tensile strength of PPO composite increases by 20% compared to pure PPO material, and the elongation at break is maintained at 123%, the impact strength is 14.5 kJ/m²， and the interlayer shear strength is 32 MPa. As the amount of modified carbon fiber added increases, the friction coefficient of the composites shows a trend of first increasing and then decreasing, and reaches its highest point when the amount of modified carbon fiber added is 4%.

In order to elucidate the effect of chain structure characteristics on the surface roughening and bulk properties of biaxially oriented polypropylene films (BOPP). The crystallization behavior and homogeneous polycrystallinity of three polypropylene (PP) granules with different chain structures were compared. The porosity, roughness, tensile mechanics, thermal shrinkage, dielectric properties and electrical breakdown field strength of BOPP films at different temperatures were tested. The results show that the chain structure with low tacticity (96.2%) and wide molecular weight distribution (5.35) is conducive to the formation of β crystals and uniform spherulite morphology, ensuring the ideal roughening morphology. Although the roughening form of BOPP film prepared by high-tacticity (97.4%) and narrow-distribut (4.34) granules is not optimal, the porosity is 9% and the surface roughness is 0.42 μm, which can meet the requirements of the capacitive film industry standard. Compared with the control films, the transverse tensile strength is 269 MPa, the transverse elastic modulus is 3 692 MPa, and the breakdown field strengths are 668 V/m (25 ℃) and 518 V/m (125 ℃). Appropriate adjustment of the PP chain structure can take into account the surface roughening and bulk performance, and provide useful inspiration for the design and development of high-performance roughening film for oil-immersed AC capacitors.

The pyrolysis kinetics of silicone rubber insulators (SiR) in nitrogen (N₂) and air environments were studied by thermogravimetric analysis (TGA). Three transformation models, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman (FR) methods, were applied to calculate activation energy and pre-exponential factors. The average activation energies of FWO, KAS, and FR methods under N₂ atmosphereare were 421.46, 431.60, 433.98 kJ/mol, respectively. The pre-exponential factor ranged from 10⁹ to 10¹⁶, which illustrated that the pyrolysis was independent of surface area. Under the air atmosphere, the average activation energies of FWO, KAS, and FR methods were 127.21, 120.93, 123.38 kJ/mol, respectively. The value of pre-exponential factor ranged from 10⁸ to 10⁹, and pyrolysis was controlled by surface area. The thermodynamic properties of the reaction under N₂ atmosphere, such as enthalpy changes (ΔH), Gibbs free energy (ΔG) and entropy change (ΔS) were much higher than that under air atmosphere, confirming the complexity of the reaction in N₂. The results of the study contribute to a deeper understanding of the combustion mechanism of SiR and provide a reference for its feasibility as a more effective high-temperature resistant material.

In order to improve the toughening efficiency of polypropylene (PP) and study its toughening mechanism, PP/HDPE/EPDM blends were prepared by melt blending with PP/HDPE blends as matrix and ethylene propylene diene monomer (EPDM) as toughening modifier. The results show that the core-shell structure of EPDM and HDPE is dispersed in the matrix, and the interaction force between EPDM and matrix is enhanced. EPDM promotes the crystallization of PP, but inhibits the crystallization of HDPE, thereby refining the dispersed phase of the core-shell structure. With the increase of EPDM content (4%~12%), the impact strength of PP/HDPE/EPDM blends is enhanced, and EPDM can toughen PP while slowing down the rapid decline of PP tensile strength. When the EPDM content is up to 16%, the impact strength of the blend reaches 11.18 kJ/m², which is 158% higher than the PP/HDPE blends. The toughening mechanism of PP/HDPE/EPDM blend is the cavitation effect of EPDM shell and HDPE core structure, which enhances its energy absorption.

Na-GMMT/TPS pellets (TPS for short) were prepared with sodium montmorillonite as filler. TPS was blended with PBAT in different proportions, and TPS-PBAT composites were prepared by twin-screw extruder. The structure and properties of TPS-PBAT composites were characterized by universal material testing machine, X-ray diffraction (XRD), thermogravimetric analyzer (TG) and scanning electron microscope (SEM). The results show that when TPS is used as matrix, the tensile strength of the composites can be greatly improved while maintaining good elongation at break. The elongation at break of TPS-PBAT-4 composites is 233.3% and the tensile strength is 18.9 MPa. With the increase of TPS content, the diffraction peaks of the composites gradually flatten, indicating that the addition of TPS reduces the crystallinity of the composites. The addition of TPS improves the thermal stability of corn starch and PBAT. When PBAT is used as matrix, the compatibility between TPS and PBAT is poor. When TPS is used as matrix, there is no obvious boundary between TPS and PBAT, and it shows better compatibility.

Waterborne antioxidant is a necessary additive in the flocculation stage of acrylonitrile butadiene styrene (ABS) resin production process, which can improve the thermal oxidative aging of ABS resin. The addition process and flocculation process of waterborne antioxidant have an important influence on the performance of ABS resin. ABS graft copolymer latex with a core-shell ratio of 60∶40 was prepared by emulsion graft polymerization. The effects of temperature of waterborne antioxidant and flocculant composition on thermal oxidative aging properties of ABS graft copolymer were studied. ABS resin was prepared using melt blending technology. The effects of temperature of waterborne antioxidant and flocculant composition on mechanical properties and apparent properties of ABS resin were investigated. The results show that the ABS graft copolymer has better thermal oxidative aging properties when the temperature of waterborne antioxidant is higher than 60 ℃. The oxidation induction period of ABS graft copolymer prepared using sulfuric acid flocculant is longer than that prepared using magnesium sulfate flocculant. The addition temperature of antioxidant and the composition of flocculant have no effect on the mechanical properties of ABS resin, but have an obvious effect on its apparent properties such as whiteness and yellow index.

Functionalized graphene modified by silane coupling agents was added to phenolic resin to prepare phenolic resin composites, and the effects on the flame retardancy, thermal properties, and mechanical properties of the composites were investigated. The results showed that the phenolic resin composite with a 30% mass fraction of functionalized graphene had a limiting oxygen index (LOI) of 46.6% and an UL-94 rating of V-0. The tensile strength and flexural strength of the material were increased by 34.42% and 13.27% respectively compared with pure phenolic resin. At the same time, the thermal stability was also effectively enhanced.

The rotating disc of the disc-screw microinjection molding machine determines its plasticizing performance, but the structural design of the rotating disc often depends on designer's experience and lacks theoretical basis. In this study, the multiphysics coupling finite element model of the plasticizing unit with a rotating disc was established, and the rotating discs with different structural parameters were simulated under the same process parameters, aiming at plasticizing performance to obtain the optimal structure of the rotating disc. Furthermore, the new rotating disc optimized for rapid processing by metal 3D printing was used for experimental verification. Polypropylene (PP), polylactic acid (PLA) and high-density polyethylene (HDPE) were respectively used for injection mass repeatability experiments, tensile experiments and thermodynamic properties experiments. The experimental results were analyzed to verify that the new rotating disc had better plasticizing properties. The results show that the multiphysical field simulation can provide quantitative analysis basis for the optimal design of the rotating disc structure of the disc-screw microinjection molding machine, and the metal 3D printing can provide technical means for the rapid development of the rotating disc.

The performance stability of automotive nylon 12 (PA12) tube under typical working conditions is very important for the reliability of automotive tube. The paper aims to explore the influence factors of temperature and humidity conditions on the dimensional characteristics and mechanical properties of PA12 tube. After gradient time treatment of four kinds of PA12 tubes under six different temperature and humidity conditions, a series of mechanical properties tests were carried out, and the effects of temperature and humidity and treatment time on the length, diameter change rate and tensile strength of four kinds of PA12 tubes were analyzed. The results show that higher temperature and humidity and longer treatment time will lead to greater dimensional change, and the dimensional change rate of PA12 five-layer tube is significantly lower than that of single-layer tube and double-layer tube. With the increase of temperature and humidity and the extension of treatment time, the tensile strength of the five-layer tube showed a decreasing trend, and the change of tensile strength of the five-layer tube was stable. The influence of temperature on the tensile properties of PA12 tube is lower than that of humidity. The research results provide a reference for the application of PA12 material in automotive industry.

The frost resistance of geopolymer rubberized concrete (GPRC) with 0, 5%, 10%, and 15% of mass fraction of rubber content was investigated through mechanical property tests and freeze-thaw cycle tests. The optimal rubber content for the best frost resistance of GPRC was explored by comparing and analyzing the appearance damage, mass loss, relative dynamic elastic modulus loss, and strength loss. Compared with GPRC without rubber, the compressive strength of GPRC with 5%, 10%, and 15% rubber content decreased by 6%, 13%, and 22%, respectively. The splitting tensile strength decreased by 17%, 21%, and 35%, respectively. The flexural strength decreased by 6%, 12%, and 31%, respectively. As the number of freeze-thaw cycles increased, higher rubber content resulted in less appearance damage and better integrity of GPRC. After 100 freeze-thaw cycles, the mass loss rates of GPRC0 to GPRC15 were 6.5%, 6.3%, 3.7%, and 1.7%, respectively. The relative dynamic elastic modulus losses were 46.77%, 44.09%, 29.81%, and 20.69%, respectively. GPRC10 and GPRC15 showed stable mass loss and relative dynamic elastic modulus loss after 75 freeze-thaw cycles. The compressive strength, splitting tensile strength, and flexural strength all gradually decreased with increasing freeze-thaw cycles. However, the loss rate decreased with increasing rubber content. The increase in rubber content could slow down the loss rate of GPRC except for the splitting tensile strength. For GPRC with more than 10% rubber content, the splitting tensile strength would accelerate the decline after 75 freeze-thaw cycles. The study indicates that the addition of rubber can effectively improve the frost resistance of GPRC, and the higher the content, the better the frost resistance. However, the strength of the concrete is reduced at the same time. From the perspective of frost resistance, without considering the decay of splitting tensile strength, 15% is the optimal rubber content. Considering the splitting tensile strength, 10% is the optimal rubber content. Taking into account the actual application, a rubber content of 10% is recommended.