Industry Analysis
XIE Jinzhao, XIE Pengcheng
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The K 2025 International Plastics and Rubber Exhibition in Düsseldorf， Germany concluded successfully， showcasing new ideas， technologies， and products in the injection molding field from exhibitors worldwide. With the theme “The Power of Plastics： Green⁃Smart⁃Responsible” K2025 focused on hot topics such as sustainable development （circular economy， low⁃carbon initiatives）， smart manufacturing， and industry responsibility. The event presented innovative solutions in the injection molding industry related to circular economy， digital intelligence， and cost⁃efficiencypetpla.netpetpla.net. In this paper， we review the technological releases and application cases from exhibitors along the main themes of K2025， highlight key innovations， and further explore future development trends of the injection molding industry.
Materials and Properties
CHEN Yijie, ZHANG Zhen, JIANG Lai, ZHAO Shicheng
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In this study， low⁃molecular⁃weight poly（butylene succinate） （PBS） was chain⁃extended through reactive extrusion using benzoyl peroxide （BPO） as a radical initiator in a twin⁃screw extruder. The influence of BPO content on the viscosity⁃average molecular weight， melt flow rate， crystallization behavior， mechanical properties， and rheological characteristics of the modified PBS was systematically investigated. Results showed that the addition of a small amount of BPO significantly increased the viscosity⁃average molecular weight from 103 878 g/mol to 147 475 g/mol， while the melt mass flow rate decreased from 21.1 to 4.5 g/10 min. Moreover， the melt crystallization temperature rose markedly from 63.1 to 94.3 ℃. In terms of mechanical performance， the modified PBS exhibited substantial improvements： tensile strength， flexural strength， impact strength， and flexural modulus increased by 13.2 %， 53.9 %， 40.5 %， and 40.0 %， respectively. Concurrently， its melt rheological behavior was notably enhanced， indicating improved melt strength and processability. This work not only presents an effective and scalable strategy for PBS chain extension but also offers valuable insights for optimizing the processing and expanding the application potential of bio⁃based PBS materials.
WANG Yu, HUANG Ying, LIU Zhongping, HAO Xiaofei, MAO Chaoying
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To overcome the inherent limitations of shear⁃thickening fluids （STFs）， notably their fluidity and susceptibility to leakage under ambient conditions， we developed a novel solid⁃like shear⁃thickening gel film by encapsulating an STF composed of SiO2 nanoparticles and poly（ethylene glycol） （PEG） within a poly（vinyl alcohol） （PVA） matrix via solution blending. This strategy leverages the formation of a three⁃dimensional physically cross⁃linked network， effectively immobilizing the STF while simultaneously enhancing the mechanical performance of the composite. Microstructural analysis revealed that in the wet gel state， the composite containing 50 wt% SiO2 exhibited a hierarchical dispersion morphology， featuring monodispersed nanoparticles （~360 nm） coexisting with micron⁃scale agglomerates （0.8~10 μm）. Upon dehydration， the SiO2 nanoparticles self⁃assembled into a heterogeneous concentration gradient along the pore walls of the PVA porous skeleton， thereby preserving the interconnected porous architecture. Notably， increasing the SiO2 loading to 67.5 wt% promoted stronger van der Waals interactions and interfacial hydrogen bonding， leading to the formation of larger agglomerates （20~110 μm） and a ~36 % reduction in average pore diameter compared to the 50 wt% system. Mechanical testing demonstrated exceptional performance for the 50 wt% SiO2 composite： it exhibited a 1.43⁃fold increase in tensile strength， an 8.4⁃fold enhancement in elongation at break， and a remarkable 9.2⁃fold improvement in toughness relative to pristine PVA. These improvements are attributed to four synergistic reinforcement mechanisms： （i） the formation of an extensive hydrogen⁃bonding network at the PVA⁃SiO2， PEG⁃PVA， and PEG⁃SiO2 interfaces； （ii） stress field superposition induced by rigid SiO2 nanoparticles； （iii） the plasticizing effect of PEG， which facilitates polymer chain mobility and rearrangement； and （iv） reversible energy dissipation enabled by the dynamic shear⁃thickening behavior of the embedded STF.
HA Enhua, CHEN Yuhong, JI Jianchao, ZHANG Xuan, YAN Luke
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This study presents the development of an organic⁃inorganic hybrid peelable protective coating tailored for poly（methyl methacrylate） （PMMA） aeronautical transparent components. A water⁃based polyurethane resin served as the organic matrix， while nano⁃silica particles were synthesized via the sol⁃gel method to form the inorganic phase. To enhance compatibility and dispersion， the nano⁃silica particles were surface⁃modified using the silane coupling agent 3⁃methacryloxypropyltrimethoxysilane （MPS）. The microstructure and chemical interactions within the nanocomposite were characterized by transmission electron microscopy and Fourier⁃transform infrared spectroscopy. Results confirmed that the methacryloxy groups of MPS chemically reacted with the waterborne polyurethane， establishing strong interfacial bonding between the organic and inorganic phases. When the nano⁃silica loading was 5 wt%， the coating exhibited a 180° peel strength of 0.12 kN/m， a 42 % increase in tensile strength， and a 21 % improvement in abrasion resistance compared to the neat polyurethane coating. These enhancements demonstrate the potential of this nanocomposite system as a high⁃performance， removable protective layer for sensitive optical surfaces in aerospace applications.
ZHENG Yanan, WANG Bofeng, WANG Ruiqi, WANG Rui, ZU Lei, LIU Yang, WANG Xiaodong, LIAN Huiqin
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Polyaniline （PANI）/black phosphorus （BP） composites were synthesized via in situ polymerization， using aniline as the monomer and BP as a functional filler. Both half⁃cells and full⁃cells were assembled with the PANI/BP composites serving as the anode material for lithium⁃ion batteries. The effect of PANI content on electrochemical performance was systematically investigated through cyclic voltammetry， electrochemical impedance spectroscopy， and long⁃term cycling stability tests. The results confirm the successful fabrication of PANI/BP composites， with PANI uniformly coating the surface of BP particles and forming strong interfacial interactions. The electrochemically inert PANI matrix effectively mitigates BP oxidation and suppresses its large volume expansion during lithiation/delithiation. Electrochemical characterization revealed that the electrical conductivity of the composites increased with higher PANI content， thereby enhancing overall electrode conductivity. In cycling tests， the composite containing 20 wt% BP delivered the best performance， achieving a high specific capacity of 794.7 mAh/g after 1 000 cycles at a current density of 4 A/g. These findings highlight the potential of PANI/BP composites as high⁃performance， stable anode materials for next⁃generation lithium⁃ion batteries.
LIU Jiahuan, ZHANG Kun, GAO Yuanyuan, WANG Ruoying, XIE Jazhuo, XU Jing
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In this study， polycarbodiimide （PCDI） was melt⁃blended with poly（butylene adipate⁃co⁃terephthalate） （PBAT） exhibiting a high initial acid value of 36.16 mg KOH/g （equivalent to 36.16 mol/t） to fabricate composite films. An indoor accelerated aging test was conducted to simulate environmental degradation， and the structural and performance changes of the films before and after aging were systematically characterized. The results revealed that increasing PCDI content effectively reduced the acid value of PBAT； with the addition of 1 wt% PCDI， the acid value decreased to 7.71 mol/t. Concurrently， the mechanical and barrier properties of the composite films were significantly enhanced： tensile strength increased by 132.6 % （transverse direction） and 30 % （machine direction）， elongation at break improved by 81.3 % and 95.4 %， respectively， and water vapor barrier performance was enhanced by 64.9 %. Accelerated UV aging tests further demonstrated that an appropriate amount of PCDI markedly improved the weatherability of PBAT⁃based biodegradable films. Based on comprehensive evaluation， the optimal PCDI loading for PBAT with an acid value of approximately 30 mol/t was determined to be 1 wt%.
LIU Jun, CHEN Jianping, WANG Weichen, YANG Fei, MA Jinglong, LIAN Meng
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This study explores the effect of various surfactants on the morphology， thermal stability， and performance of aluminum diethylphosphinate （ADP） nanoparticles in epoxy resin （EP）. Using scanning electron microscopy， X⁃ray diffraction， Fourier⁃transform infrared spectroscopy， and thermogravimetric analysis， it was found that sodium dodecyl benzene sulfonate effectively suppressed nanoparticle agglomeration， while cetyltrimethylammonium bromide induced a morphological transformation of ADP from irregular particles to well⁃defined rod⁃like structures. This structural evolution enhanced both the crystallinity and thermal stability of ADP. More importantly， surfactant⁃mediated morphology control significantly improved the dispersion and interfacial compatibility of ADP within the EP matrix. As a result， the modified composites exhibited simultaneous improvements in mechanical properties and flame retardancy. These findings demonstrate that rational selection of surfactants offers an effective strategy to tailor the morphology and functionality of ADP nanoparticles， thereby optimizing their dual role as flame retardants and toughening agents in epoxy systems.
ZHOU Xiangyang, WANG Yashi, XIAO Min
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In this study， agricultural waste straw underwent alkalization treatment followed by solid⁃phase grafting modification. The modified straw， in combination with starch， was utilized as the base material for producing composite foaming materials. Sodium bicarbonate （NaHCO3） served as the foaming agent， calcium carbonate （CaCO3） as the nucleating agent， and glycerol and urea acted as plasticizers. These components were processed into modified straw/starch/polyvinyl alcohol （PVA） composite foaming materials using an extrusion injection molding foaming process. The impact of varying glycerol content， NaHCO3， and CaCO3 concentrations on the apparent density and porosity of the resulting foaming materials was systematically investigated. Furthermore， the influence of modified straw content on the mechanical properties， contact angle， apparent density， and microstructure of the starch/PVA foamed materials was assessed. Results indicated that an optimal formulation mass ratio of starch：modified straw∶PVA∶CaCO3∶NaHCO3∶glycerol at 1∶0.3∶0.25∶0.1∶0.12∶0.15 yielded materials with superior mechanical performance， enhanced processability， and a high degradation weight loss rate. The modified straw/starch/PVA foaming material exhibited a static contact angle of 90.74 ° and achieved an oil absorption capacity of 9.6 g/g， demonstrating significant potential for applications in oil⁃water separation.
Processing and Application
ZHONG Shanbin, CHEN Ke, XUE Ping, ZHAO Rong, HAN Minyuan, ZHANG Shuai, HAN Jingjing
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In this study， physical and mathematical models were developed for the feeding， plasticizing， and homogenizing sections of a parallel counter⁃rotating twin⁃screw extruder. The extrusion process of modified double⁃base propellant was simulated using a combination of EDEM， ANSYS Fluent， and Polyflow software. The influence of key geometric parameters⁃specifically， the screw intermeshing clearance and the screw⁃barrel clearance⁃on critical extrusion variables such as temperature and pressure was systematically investigated. The simulation results provide valuable insights into the relationship between screw clearance design and process stability， offering practical guidance for optimizing twin⁃screw extruder configurations. This work contributes to enhancing the safety and reliability of the modified double⁃base propellant molding process by enabling more precise control over thermal and mechanical conditions during extrusion.
YU Zhong, SHANGGUAN Yuanshuo, LIU Zhiqing, HUANG Yibin, ZHANG Kai, LIU Hesheng, KUANG Tangqing, SHI Huiping, XU Zhechen
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This study investigates the impact of key process parameters in overflow⁃type water⁃assisted injection molding on short glass fiber blockage within the molded part’s internal channels. Experimental results reveal that melt temperature in the range of 230~240 ℃ significantly affects fiber blocking behavior. Specifically， increasing the melt temperature from 230 to 240 ℃ shifts the blockage location from the entire main cavity flow path to the distal end of the flow channel. Similarly， a water injection delay time of 3~5 s exerts a pronounced influence： extending the delay from 3 s to 5 s causes the blockage zone to migrate from the mid⁃section of the flow channel toward its proximal half. Additionally， injection pressure in the range of 6~8 MPa shows a clear effect， raising the pressure from 6 to 8 MPa relocates the blockage from the latter half of the channel to several discrete segments near the middle. These findings provide valuable insights into controlling fiber distribution and mitigating blockage in water⁃assisted injection molding of fiber⁃reinforced polymers.
WANG Zhenchao, XIANG Aimin, LIU Le, XU Lu, YOU Qijiang, QIE Jichun, ZHANG Qiuju
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Based on the theories of polymer crystallization kinetics and molecular chain reptation， this study elucidates the microstructural mechanisms governing butt fusion welding in polyethylene （PE） pipes. It identifies the initial temperature field at the welding interface， and its dynamic evolution， as the central factor dictating the mechanical integrity of the welded joint. By approximating the interfacial thermal behavior as a two⁃dimensional heat transfer model， a quantitative relationship was established between key process parameters and the spatiotemporal distribution of the temperature field throughout the welding cycle. Using thermal simulation software and a controlled⁃variable methodology， the study systematically quantified the effects of ambient conditions， including ambient temperature， wind speed， and heat source removal time， on the peak temperature and minimum interface temperature during welding. The research demonstrates that interfacial forces play a dominant role in shaping the initial temperature field. Furthermore， it reveals a nonlinear coupling between the maximum temperature in the molten zone and the minimum temperature at the interface. Notably， singularities in the temperature gradient were observed during the dynamic evolution of the thermal field in thick⁃walled pipes under varying environmental conditions， phenomena not previously reported in the literature. These findings provide a robust theoretical foundation for optimizing both welding protocols and on⁃site environmental controls in the fabrication of thick⁃walled PE pipe joints， ultimately enhancing weld quality and structural reliability.
Additive
WANG Hongkun, REN Yueqing, SUN Xiaojie, DONG Yang, LI Yafei, WU Fumei
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Crosslinking agents play a pivotal role in determining the powder stability， processing behavior， and final properties of rotationally molded crosslinked polyethylene （RM⁃XLPE）. This study systematically investigates the melting behavior and thermal decomposition characteristics of three distinct crosslinkers， and further evaluates their impact on the storage stability of RM⁃XLPE powders， crosslinking kinetics， and rotational molding performance of polyethylene/crosslinker blends. Results show that Crosslinker 1# exhibits the lowest peak melting temperature （Tpeak） and onset volatilization temperature （Tonset）， along with a rapid volatilization rate. While this leads to poor powder storage stability， it yields rotationally molded parts with smooth inner surfaces and excellent processability. In contrast， Crosslinker 3# demonstrates higher Tpeak and Tonset， offering superior thermal stability and initiating crosslinking at a relatively low temperature （140 ℃）； however， it results in uneven inner wall morphology and compromised processing characteristics. Crosslinker 2# strikes an optimal balance， featuring relatively high Tpeak and Tonset， a slow volatilization rate， good powder stability， smooth inner surface finish， and favorable processing behavior. Based on this comprehensive evaluation， Crosslinker 2# is identified as the most suitable crosslinking agent for RM⁃XLPE applications， offering an effective compromise between storage stability， processability， and product quality.
ZHANG Qinghai, CHEN Rupan, WANG Yuling, WANG Xiaojun
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In this study， a sustainable and eco⁃friendly phosphorus/nitrogen⁃containing bio⁃based flame retardant （denoted by PN） was synthesized from phytic acid and nicotinamide， and subsequently incorporated into epoxy resin （EP） composites. The results demonstrate that the addition of PN significantly enhances the flame⁃retardant properties of EP： the peak heat release rate and total heat release were reduced by 41.9 % and 34.5 %， respectively. Moreover， PN effectively suppressed smoke production and the release of toxic gases while promoting the formation of a robust char residue. Mechanistic investigations indicate that PN operates through a dual⁃mode action⁃catalyzing the formation of a dense， protective char layer in the condensed phase， and scavenging free radicals while diluting flammable gases in the gas phase. These synergistic effects underscore PN’s potential as a high⁃performance， bio⁃derived flame retardant， offering a promising pathway toward environmentally benign flame⁃retardant materials.
Plastic and Environment
LIU Tianyuan, JI Junhui, YAN Guochun, HUANG Dan
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This review systematically examines biodegradation detection methods in relation to the progressive stages of degradation， ranging from residual polymers and disintegrated fragments to intermediate metabolites and fully mineralized products， with a focus on accurately quantifying the extent of biodegradation. Existing analytical techniques are comprehensively compared and evaluated in terms of their accuracy， sensitivity， and practical efficiency in determining degradation degrees. The analysis provides critical guidance for selecting appropriate biodegradation assessment strategies tailored to specific materials and environmental conditions. Notably， the review advocates for redefining the endpoint of “complete biodegradation” not solely by the presence of mineralized end⁃products， but by the formation of biologically assimilable intermediates that can be readily utilized by microorganisms. This paradigm shift holds significant potential to shorten testing cycles and paves the way for the development of accelerated， biologically relevant biodegradation detection protocols.
CHEN Caohong, CHI Dequan, WANG Jinggang, LIU Fei, ZHU Jin
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In this study， a bio⁃based amorphous polyester with a high glass transition temperature （Tg） was employed as the hard segment to develop a novel thermoplastic polyether ester elastomer by incorporating a polyether soft segment. Starting from the renewable monomer 2，5⁃furandicarboxylic acid， an amorphous polyester （denoted by PCEF） was synthesized via copolymerization with ethylene glycol and 2，2，4，4⁃tetramethyl⁃1，3⁃cyclobutanediol， achieving a Tg as high as 110 ℃. Building upon this polyester， a series of bio⁃based thermoplastic polyether ester elastomers （PCEF⁃PTMG） were prepared by introducing poly（tetramethylene glycol） （PTMG） as the soft segment. Mechanical testing revealed that when the PTMG content reached 30 wt%， the resulting material exhibited characteristic thermoplastic elastomeric behavior， with a tensile modulus of 139 MPa， tensile strength of 47 MPa， and elongation at break exceeding 500 %. This study demonstrates the feasibility of using high⁃Tg， bio⁃based amorphous polyesters as effective hard segments for high⁃performance thermoplastic elastomers. Further structural optimization holds promise for the development of next⁃generation， sustainable thermoplastic polyether ester elastomers.
Machinery and Mould
TANG Yuxuan, YANG Weimin, WANG Tao, HU hemin, DING Yumei
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To enhance energy efficiency in injection molding， this study proposes and experimentally evaluates an innovative integrated circulation system that combines mold cooling with plastic material preheating. In this system， waste heat recovered from the mold cooling circuit is effectively repurposed to preheat and dry raw plastic pellets. Experimental results demonstrate that the heat exchanger rapidly reduces surface moisture during the initial preheating stage， achieving a peak drying rate of 0.29 %/min. In contrast， the conventional electric dryer excels at removing internal moisture， reliably lowering the final moisture content to 0.02 %. Energy consumption analyses reveal significant differences during the preheating phase. For example， drying 500 g of polycarbonate with an initial moisture content of 0.40 % consumes approximately 15 kW·h when using the dryer alone， the highest among all tested configurations. By contrast， preheating exclusively via the combined circulation system requires only about 8 kW·h， representing the lowest energy demand. A hybrid approach （using both systems） yields intermediate consumption. Notably， power usage during the actual production （injection molding） stage shows negligible variation across the three preheating methods； thus， total energy savings are predominantly attributed to the preheating phase. The influence of initial moisture content on overall energy consumption is relatively minor， whereas increasing material mass leads to a substantial rise in energy demand， though the heat recovery system maintains consistent energy⁃saving benefits. The system′s applicability is further validated through trials with polyamide 66， where it achieves a 4 kW·h reduction in electricity consumption after 60 min of preheating， confirming its potential for broad industrial adoption.
YE Weiwen, JIANG Bingchun, FENG Jing, CHEN Zhensen
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This study addresses the challenges associated with mold design for plastic straight⁃pipe water chambers used in automotive heat exchange systems. An innovative mold featuring a sliding⁃block and dual⁃angled ejector composite structure is proposed. Through a detailed analysis of the component’s geometry and molding complexities， a comprehensive mold design strategy is developed， encompassing critical aspects such as gating system layout， demolding mechanism， and parting line configuration. The operational sequence of the mold is also thoroughly described. In comparison with conventional mold designs， this approach demonstrates notable innovations in both structural configuration and pre⁃deformation compensation techniques. Furthermore， the defect rate and practical applicability of the proposed mold are evaluated. The results show that the new design effectively resolves key molding issues for straight⁃pipe water chamber components， significantly enhancing product quality and manufacturing efficiency. This work offers valuable insights and a novel methodology for the mold design of complex automotive plastic parts.
FEI Qiang, ZHANG Weihe
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Guided by the structural features of the glove compartment cover in new energy vehicles， an innovative mold design was developed with a focus on four key dimensions： part quality， production efficiency， cost⁃effectiveness， and environmental sustainability. By implementing a shape⁃conforming reinforcement structure aligned with vehicle light weighting requirements， the average wall thickness of the plastic component was reduced from 2.5 mm to 2.0 mm， achieving approximately 15 % material savings. The surface quality of the molded parts was significantly enhanced， and fully automated production was realized. Through mold flow analysis， an optimized gating system， combining a hot runner， a conventional cold runner， and an arc⁃shaped submarine gate， was adopted， reducing the scrap rate from 5 % to 1 %. Furthermore， dimensional accuracy was improved to meet the MT3 tolerance grade specified in GB/T 14486—2008. The cycle time was shortened from 35 s to 26 s， and cooling efficiency increased by 25 %， thanks to the integration of partitioned conformal cooling channels and a closed⁃loop temperature control system. Collectively， these advancements have doubled the overall production capacity of the mold， demonstrating a robust and sustainable approach to high⁃performance injection molding for automotive interior components.
Review
WANG Xiaoyang, LI Shuhong, WANG Xiangdong
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This article presents a comprehensive overview of the synthesis strategies， structural characteristics， and multifunctional properties of polysilazane⁃based porous materials. Emphasis is placed on their emerging applications in high⁃temperature ceramic foams， lightweight yet high⁃strength structural components， thermal insulation systems， electromagnetic wave absorbers， as well as lubricious and antifouling coatings. The review highlights the significant scientific potential and promising market prospects of these materials， underscoring their versatility and growing importance in advanced material science and engineering.
WU Yingkui, QI Wen
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This review summarizes recent progress in the development and application of hydrogels for marine antifouling. The primary drivers of marine biofouling， and associated material degradation， are analyzed， followed by an overview of key advances in hydrogel⁃based antifouling strategies. Hydrogels exert their antifouling effects mainly through surface hydrophilicity and low interfacial energy， which create a hydration barrier that effectively resists the adhesion of marine organisms. Both natural polymer， based hydrogels （e.g.， starch， cellulose， sodium alginate， chitosan， and protein⁃derived systems） and synthetic polymer， based hydrogels ［e.g.， poly（acrylic acid）， polyacrylamide， poly（ethylene glycol）， and poly（vinyl alcohol）］ have demonstrated promising antifouling performance in marine environments. However， the complexity and harshness of real⁃world marine conditions， such as high salinity， dynamic hydrodynamics， UV exposure， and microbial activity， pose significant challenges to the long⁃term stability and functionality of hydrogel coatings. Future research should focus on designing multifunctional， intelligent， and eco⁃friendly hydrogel materials to address the challenges of marine antifouling.
