Materials and Properties
LIU Lin, SHOU Tao, LIAO Feiyang, ZHENG Zikang, FENG Xinhe, ZHAO Xiuying
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106 )
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Bio⁃based thermoplastic polyurethanes （BPUs） were synthesized using bio⁃derived 1，5⁃pentanediyl diisocyanate and poly（1，3⁃propanediol）， with either isosorbide （IS） or a combination of IS and 3⁃allyloxy⁃1，2⁃propanediol （APD） as chain extenders. These BPUs were employed to toughen polylactic acid （PLA） via dynamic vulcanization. The influence of chain extender composition and structure on the toughening performance of PLA/BPU blends was systematically investigated. The PLA/BPU⁃IS/APD blend demonstrated superior mechanical properties， achieving tensile strength of 47.22 MPa， elongation at break of 133.8 %， and impact strength of 54.21 kJ/m²， while maintaining a high bio⁃based content of 99.4 %.
ZHAO Xiaohuan, WANG Yansen, SUN Jingshan, DENG Jingqian, QI Liya, HOU Dandan, WANG Chunyao, TAN Xinyu
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52 )
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DDAB⁃PLA nano⁃microparticles were synthesized via an improved emulsification method， with particle size controlled by adjusting the oil/water phase ratio and emulsifier concentration. The cytotoxicity of DDAB⁃PLA particles with varying cationic contents was also evaluated. The resulting particles exhibited a nano⁃ to micro⁃scale size distribution， with an average diameter of approximately 490 nm. By modulating the aqueous phase volume and emulsifier concentration， the particle size could be precisely tuned within the range of 169~786 nm. Furthermore， DDAB⁃PLA nano⁃microparticles demonstrated negligible cytotoxicity toward L929 cells and DC， indicating excellent biocompatibility.
HUANG Geng, Bekbolatovich Sagin Abay, WU Daming, WANG Xiaojie, GAO Xiaolong, SUN Jingyao, HUANG Yao, XU Hong, ZHENG Xiuting
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95 )
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This study reported an investigation on the effects of gamma⁃ray irradiation modification above the melting point on the wear resistance of polytetrafluoroethylene （PTFE）. The crystalline structure and tribological properties of PTFE before and after irradiation were characterized using differential scanning calorimetry， scanning electron microscopy， X⁃ray diffraction， Fourier⁃transform infrared spectroscopy， and tribological testing. Results demonstrated that irradiation significantly enhanced PTFE's crystallinity. Under optimized conditions， the modified PTFE exhibits a 3.31⁃fold improvement in wear resistance and a 78 % reduction in friction coefficient， demonstrating superior tribological performance.
LE Deliang, WU Qimin, LIN Zhonghua, PEI Kemei
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61 )
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Underwater concrete repair materials are specialized substances designed for restoring submerged concrete structures. Epoxy resin， with its rapid underwater curing capability， high strength， and superior adhesion properties， serves as an ideal base material for such applications. This study developed a water⁃based epoxy adhesive system and systematically investigated the factors affecting its repair performance. The research examined the influence of component ratios， curing conditions， interface roughness， concrete strength， and surface environment on the composite material's bonding properties. Results indicated that optimal bonding strength was achieved after 7 days of underwater curing at 25 ℃， compared to shorter curing periods at higher temperatures. The study identified an optimal resin⁃to⁃curing agent ratio of 3.5∶1 and demonstrated that increased interface roughness and surface permeability significantly enhanced bonding performance. Furthermore， surface conditions such as extract presence or microorganism colonization were found to moderately affect interface adhesion. These findings provide valuable guidance for optimizing underwater concrete repair applications.
LI Yaxin, XIE Junlong, LI Chenghao, CAI Shaojun
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112 )
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A UV⁃cured PAA⁃PAM copolymer hydrogel was synthesized using acrylic acid and acrylamide as monomers， N，N'⁃methylenebisacrylamide as a crosslinker， and Irgacure™ 2959 as a photo⁃initiator. The hydrogel properties were comprehensively characterized using FTIR， SEM， mechanical testing， and rheological analysis. This study systematically investigated how glycerol incorporation affects the hydrogel's mechanical strength， viscoelasticity， water retention， adhesion， and temperature resistance. Results indicated that glycerol significantly enhanced the hydrogel's performance， improving its elongation at break （631.8 %）， tensile strength （53.0 kPa）， adhesion， and extreme temperature tolerance. Optimal properties were achieved with an acrylic acid⁃to⁃acrylamide molar ratio of 4∶6， 1 ‰ crosslinker concentration， and 60 vol% glycerol content. The developed hydrogel exhibits excellent comprehensive performance， making it promising for various applications requiring flexibility， durability， and environmental adaptability.
YE Xiangyu
Abstract (
60 )
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This study investigated the effects of partially replacing magnesium hydroxide with melamine cyanurate （MCA） in flame⁃retardant polyethylene cable materials. The replacement ratio was varied while maintaining the total flame retardant content. The modified materials were evaluated for mechanical properties， melt flow rate， volume resistivity， limiting oxygen index （LOI）， and UL94 vertical burning performance. Results indicated that as MCA substitution increased： （1） mechanical properties gradually declined； （2） MFR and volume resistivity remained relatively stable； （3） LOI improved before reaching a plateau； and （4） flame retardancy significantly enhanced， achieving V⁃2， V⁃1， and V⁃0 ratings at 4 %， 6 %， and 9 % MCA replacement levels （by total mass）， respectively. The findings demonstrated that optimal MCA incorporation could improve flame retardancy while maintaining acceptable material properties for cable applications.
LI Manlin, YAN Yu, GAO Bingbing, HU Zanjun, ZHANG Shuidong
Abstract (
59 )
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A high⁃adhesion thermoplastic starch⁃based hot melt adhesive （HMA） was prepared using a two⁃step method involving tartaric acid⁃modified thermoplastic starch （TPSTA1）. Ethylene⁃vinyl acetate （EVA）， rosin， and aluminum powders were incorporated into HMA via melt blending. The effects of varying EVA， rosin， and aluminum powder content on the adhesive's flow properties， adhesion strength， viscoelasticity， and compatibility were systematically investigated. Experimental results indicated that increasing the HMA （a blend of EVA and rosin） and aluminum powder contents initially enhanced adhesive strength， flowability， and surface energy， followed by a subsequent decrease. Optimized formulations significantly improved adhesive strength in copper lap joints， aluminum foil peel tests， and nonwoven fabric peel tests. Furthermore， incorporating HMA and aluminum powders disrupted the hydrogen bonding network within TPSTA1， enhancing starch chain molecular mobility. This caused a shift from predominantly viscoelastic to more viscous behavior， thereby improving the adhesive system's stability. Microstructural analysis indicated limited compatibility between TPSTA1 and rosin at high HMA contents， resulting in a sea⁃island morphology. EVA acted as a compatibility enhancer， improving interfacial adhesion. Aluminum powders dispersed uniformly at low concentrations but exhibited agglomeration tendencies at higher levels. This study provides theoretical support for optimizing the performance and expanding the application potential of thermoplastic starch⁃based hot melt adhesives.
Processing and Application
WANG Wenhao, QIU Siyuan, LI Yajiao, SUN Jingyao, WU Daming, WANG Shuyuan, XU Hong, GAI Yunqing
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67 )
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This study investigated the mechanical behavior of reinforced thermoplastic composite pipes （RTP） under internal pressure using finite element analysis. A Python⁃based parametric modeling script was developed to establish the reinforcement layer model in ABAQUS， incorporating the Hashin progressive failure criterion to predict damage initiation and progression. The simulation analyzed the effects of reinforcement layer configuration and fiber winding angles on pipeline performance. Results demonstrated that a four⁃layer reinforcement design withstood 10 MPa internal pressure with a safety margin， exhibiting only 1468 MPa stress in the innermost fibers （Hashin criterion <1）. Furthermore， fiber orientation significantly influences mechanical performance： at ±75 ° winding angles， maximum stress reduces by approximately 48 % compared to ±35 ° configurations （816.3 MPa vs. 1 569 MPa）， with the Hashin criterion decreasing to 0.278. These findings provide valuable insights for optimizing RTP design parameters to enhance structural integrity under operational pressures.
HU Yanlei, SUN Jin, HU Fa, WU Zhijun, LI Yue, WU Xiaohan
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79 )
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This study evaluated the fatigue resistance of polyethylene （PE） pipe materials using cracked round bar cyclic loading tests. A systematic investigation was conducted to assess the effects of manufacturing method （compression molding vs. extrusion）， specimen geometry， loading parameters （stress range， frequency， load ratio）， and temperature on fatigue performance. Results indicated that compression⁃molded specimens exhibited superior fatigue resistance compared to extruded pipes. Fatigue life was significantly influenced by test conditions： （1） increasing specimen diameter reduced fracture cycles， （2） higher stress ranges reduced fatigue life， with a brittle⁃ductile transition occurring at 16 MPa， （3） elevated frequencies accelerated failure， （4） increased load ratios improved fatigue resistance， and （5） higher temperatures reduced cycle counts. These findings provide critical insights for optimizing PE pipe design and performance under cyclic loading conditions.
GAO Yonghong, HE Jiale, JIN Qingping
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77 )
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This study examined the effects of elevated temperatures （20⁃220°C） on the axial compressive behavior of concrete⁃filled glass fiber reinforced polymer （GFRP） tubular columns. Experimental investigations were conducted on GFRP tubes， concrete cubes， and composite columns with two different specifications， subjected to heating durations of 2 and 4 hours. The study evaluated circumferential tensile properties of GFRP tubes， compressive strength of concrete， and their combined influence on column performance. Results indicated that at ambient temperature， GFRP confinement enhanced the ultimate bearing capacity of concrete columns by 4.75 times compared to unconfined specimens. However， elevated temperatures significantly degraded the mechanical compatibility between GFRP tubes and concrete， leading to progressive reductions in both ultimate bearing capacity and strain. At 220 ℃， the bearing capacity decreased by 18.73 % （2⁃hour exposure） and 20.21 % （4⁃hour exposure）. Temperature elevation proved more detrimental to axial performance than exposure duration， highlighting the importance of thermal considerations in GFRP⁃confined concrete column design.
SUN Yueying, TANG Xiaolong, ZOU Zhongyi, WANG Mengqiao, LIU Jitao
Abstract (
70 )
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This study employed molecular dynamics simulations to investigate the microstructural evolution of polyvinylidene fluoride （PVDF） during shear deformation. The effects of chain length， mixed polymerization degree， and shear strain rate on the shear behavior of PVDF were systematically examined， with analysis focusing on stress⁃strain response， end⁃to⁃end distance， mean square displacement， and radial distribution function. Results revealed that the shear deformation process exhibited three distinct stages： elastic deformation， stress yield， and stress softening. Longer polymer chains demonstrated greater resistance to unwinding， requiring higher shear stresses and exhibiting more pronounced changes in end⁃to⁃end distance. For systems with mixed polymerization degrees， the shear response was predominantly governed by long⁃chain molecules， leading to increased shear modulus and chain⁃length⁃dependent variations in end⁃to⁃end distance. Furthermore， higher strain rates necessitated greater shear stresses， induced larger changes in molecular conformation， and impeded chain unwinding. These findings provide molecular⁃level insights into the shear⁃induced structural evolution of PVDF， offering valuable guidance for optimizing its processing and performance.
HONG Xueyin, GAO Shang
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56 )
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This study systematically investigated the influence of ten fused deposition modeling process parameters on the tensile properties of ABS parts using a Latin hypercube experimental design. The examined parameters include layer height， wall thickness， top/bottom thickness， top/bottom line direction， infill density， infill line direction， printing speed， extrusion temperature， bed temperature， and workspace temperature. Three machine learning approaches， artificial neural network （ANN）， random forest （RF）， and gradient boosting （GB）， were compared for their predictive accuracy of tensile strength and elongation at break. Results demonstrated that GB outperformed other methods， achieving superior correlation coefficients （R=0.975 9~0.981 2） and the lowest mean square errors （MSE=1~10）. RF showed intermediate performance （R=0.913 6~0.924 0， MSE=3~20）， while ANN yielded the lowest accuracy （R=0.883 5~0.892 4， MSE=5~24）. Feature importance analysis revealed infill density as the most influential parameter， contributing approximately 80 % to GB predictions compared to 40 % in RF. Other significant factors included wall thickness， infill line direction， and layer height. These findings provide valuable insights for optimizing FDM process parameters and selecting appropriate machine learning techniques for mechanical property prediction.
ZHAO Dan, SUO Shuwu, SHEN Jiyong, WANG Peng, LI Haibin, LI Zhigang
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88 )
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Straw carbon （SC）， as a sustainable material derived from agricultural waste， offers a novel approach for resource utilization in asphalt pavement applications. This study investigated the composite modification of base asphalt using SC and styrene⁃butadiene⁃styrene （SBS） through comprehensive performance evaluation， including fundamental property tests， high/low⁃temperature rheological assessments， and aging resistance analysis. Results demonstrated that SC's large specific surface area and porous structure enhanced asphalt interaction by increasing contact area and absorbing light components. At optimal concentrations （4 wt% SBS and 12 wt% SC）， the SBS⁃SC modified asphalt （SBS⁃SCMA） exhibited significant improvements in penetration， softening point， viscosity， complex shear modulus， and phase angle， achieving superior high⁃temperature performance. Notably， SC enhanced aging resistance by mitigating high⁃temperature performance degradation in SBS⁃modified asphalt. However， reduced 5 ℃ ductility， increased creep stiffness （S）， and decreased creep rate （m） indicate compromised low⁃temperature performance， suggesting this composite is particularly suitable for asphalt pavements in warmer climates. These findings provide valuable insights for sustainable asphalt modification using agricultural waste materials.
LIU Shuang, HAN Meizhao
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73 )
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This study developed triethylenetetramine⁃functionalized graphene oxide microchips （TETA⁃GOs） through covalent grafting and employed them as curing agents for epoxy⁃modified asphalt binders. The investigation focused on the influence of TETA⁃GOs on the rheological properties of the modified asphalt system. Characterization revealed that TETA⁃GOs effectively cured the epoxy resin， resulting in the formation of larger resin particle domains within the asphalt matrix. The incorporation of GOs into the epoxy crosslinking network significantly enhanced the binder's deformation resistance， elevated its high⁃temperature performance grade， and improved rutting resistance. While these modifications led to a marginal reduction in elastic recovery and an increased viscous component， the overall rheological improvements demonstrate the potential of TETA⁃GOs/epoxy resin composites for high⁃strength pavement applications. These findings provide a promising approach for developing advanced asphalt binders with superior mechanical performance.
Additive
LI Zihan, SONG Chaobo, ZHANG Jinjin, LIANG Dali, LIN Huajie
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50 )
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This study investigated calcium salt nucleating agents for enhancing the crystallization and mechanical properties of polybutene⁃1 （PB⁃1）， with particular focus on accelerating the crystal form II⁃I transformation. Three selected calcium salt nucleators were evaluated using differential scanning calorimetry to analyze thermodynamic crystallization behavior and non⁃isothermal crystallization kinetics. Results demonstrated significant improvements in crystallization properties for all modified PB⁃1 composites. Powder X⁃ray diffraction analysis revealed that calcium salt nucleators markedly accelerated the phase transition from form II to form I crystals. Furthermore， mechanical property testing showed substantial enhancement in PB⁃1 performance with calcium nucleator incorporation. These findings provide valuable insights for developing high⁃performance PB⁃1 materials through nucleating agent modification.
Plastic and Environment
FENG Shuo, LIN Xiaoqi, ZHU Yanli, GAO Weichang, WENG Yunxuan, ZAHNG Caili
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87 )
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As poly（butylene succinate⁃co⁃butylene terephthalate） （PBAT） gains widespread use as a leading biodegradable plastic， its chemical recycling has emerged as a critical component in environmental sustainability and circular economy strategies. This review comprehensively examined the current state， technological challenges， and future prospects of PBAT chemical recycling. Various approaches including hydrolysis， alcoholysis， thermochemical recovery， and biocatalytic conversion were analyzed for their ability to transform PBAT waste into valuable chemical feedstocks. The study incorporated life cycle assessment （LCA） to evaluate the environmental and economic impacts of different recycling methods. Furthermore， the paper discussed the catalytic role of policy frameworks in advancing PBAT recycling and identify existing technological and implementation barriers. The analysis concluded by highlighting the substantial potential of PBAT chemical recycling， emphasizing the synergistic importance of technological innovation， market development， and policy support in establishing a sustainable PBAT recycling ecosystem.
LIANG Yonghuang, LIU Jing, GE Dongqi
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168 )
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The resource recovery and circular utilization of waste plastics represent a critical pathway for addressing global plastic pollution and resource scarcity. Chemical recycling technologies offer distinct advantages over conventional physical methods， enabling the conversion of low⁃value plastic waste， including materials unsuitable for mechanical recycling， into valuable feedstocks through environmentally benign processes. This approach effectively transforms "white pollution" into a "white oilfield，" positioning chemical recycling as a pivotal direction for the plastic waste management industry. This review systematically analyzed current chemical recycling technologies and their industrial applications， identifies key challenges hindering China's plastic chemical recycling sector， and proposes targeted solutions. Furthermore， a forward⁃looking analysis of development trends in China's plastic chemical recycling industry was presented， highlighting its potential to drive sustainable waste management and circular economy initiatives.
SUN Ying, BAI Lin, WANG Rong, WENG Yunxuan
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101 )
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Fruits and vegetables， while nutritionally essential， face significant postharvest challenges including ongoing cellular respiration， transpiration， mechanical damage， and microbial contamination that accelerate spoilage and contribute to substantial food waste. Preservation technologies have thus become critical for extending shelf life and reducing losses. In the context of global “dual carbon” objectives and plastic restriction policies， biodegradable materials have emerged as a sustainable solution for food packaging applications. This review examined the principles of modified atmosphere packaging （MAP） and classifies current biodegradable substrate materials. The review also systematically analyzed recent advances in MAP⁃combined biodegradable packaging systems for fruit and vegetable preservation， highlighting their dual benefits in food quality maintenance and environmental protection. Finally， future development directions in this field were discussed， aiming to provide theoretical foundations and practical insights for next⁃generation sustainable preservation technologies.
WANG Zheng, XIAO Dong, HUANG Rui, SUN Xiaoqian
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47 )
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This study investigated the effects of recycled polyvinyl chloride （RPVC） particles on concrete properties by replacing 20 %~50 % of natural sand with RPVC aggregate. Specimens were subjected to six distinct humidity⁃controlled curing environments to evaluate the combined influence of RPVC dosage and curing conditions on mechanical performance. Results indicated that RPVC incorporation reduced concrete's compressive strength， with maximum reduction （50 % replacement） observed under continuous indoor curing. Both 28 day splitting tensile strength and elastic modulus consistently decreased with increasing RPVC content， showing similar curing⁃condition dependence as compressive strength. An empirical formula was derived to estimate the elastic modulus of RPVC⁃modified concrete. The enhanced deformation resistance is attributed to RPVC particles' high tensile strength， superior elastic deformation capacity， and confining pressure effect from lateral expansion. These findings provide fundamental insights for optimizing RPVC⁃recycled concrete in sustainable construction applications.
Review
LIU Wenlong, LOU Shuang, ZHENG Hao, MA Xiuqing
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59 )
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This review systematically examined recent advances in polyoxymethylene （POM） reinforcement using various fiber fillers. The reinforcing effects and mechanisms of carbon fibers， glass fibers， whiskers， basalt fibers， and natural fibers in POM composites were comprehensively analyzed. Through comparative evaluation of different filler systems， key structure⁃property relationships and performance characteristics were identified. The discussion encompassed interfacial bonding mechanisms， mechanical enhancement effects， and processing considerations for each fiber type. Finally， future perspectives on emerging trends in fiber⁃reinforced POM composites were presented， highlighting potential directions for material development and industrial applications. This work provides valuable insights for designing high⁃performance POM composites through targeted filler selection and optimization.
FENG Zhi, WANG Jin, TONG Zhe
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56 )
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Fiber fabric⁃reinforced polymer composites exhibit exceptional specific strength and tunable structural properties， enabling the design of materials with low friction coefficients and high wear resistance through careful fiber architecture and composition optimization. These characteristics make them particularly promising for aerospace and automotive applications. This review systematically reported recent advances in the tribological performance of fiber fabric/polymer composites， analyzing their lubrication and wear mechanisms across different operational conditions. The friction characteristics of various fiber types were compared and their influence on lubrication behavior and wear patterns were elucidated. Furthermore， how fabric structure governs the tribological response of composites was investigated. Finally， three critical research challenges were identified： （1） contact scale dynamics and friction stability， （2） interface optimization and modification， and （3） thermal conductivity enhancement. This work provides fundamental insights to guide the development of high⁃performance tribological polymer composites for demanding engineering applications.
DONG Shengye, CHEN Xinggang, WANG Qihao, YAO Yu, LI Ruoxuan, CHANG Jiabin, SONG Jiacheng
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Self⁃healing polymer materials， capable of autonomously repairing minor damage， have gained significant attention in medical applications. However， their performance in diverse service scenarios remains limited. This review systematically classified self⁃healing polymer materials and critically analyzes current research progress， focusing on key performance metrics including mechanical strength， toughness， and durability. Their medical applications in wound healing， drug delivery systems， bone tissue engineering， and biomedical coatings were comprehensively examined. Finally， current challenges and future development directions were discussed， providing insights for the design of next⁃generation self⁃healing polymers with enhanced clinical applicability.
Special discussion
CHANG Jiwen, LI Jianjun, MOU Bin, ZAHNG Jialong
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The global plastic pollution crisis has intensified focus on sustainable alternatives， with non⁃grain bio⁃based degradable plastics emerging as a critical solution that aligns with green development goals while safeguarding food security. While Europe and North America have progressed from technical demonstration to commercial⁃scale production， China has developed a distinctive industrial landscape led by polylactic acid （PLA） and polyamide materials， with multiple bio⁃based technologies advancing rapidly. However， significant challenges persist in four key areas： （1） comprehensive utilization of non⁃grain biomass feedstocks， （2） core industrialization technologies， （3） large⁃scale production cost reduction， and （4） policy standard implementation. To accelerate China's industry development， we proposed a four⁃pronged strategy： （i） breakthrough innovation in core technologies with enhanced commercialization pathways， （ii） optimized industrial planning for rapid capacity expansion， （iii） accelerated standards development to facilitate market adoption， and （iv） whole⁃industry⁃chain cultivation coupled with improved management and recycling systems. These recommendations aim to elevate China's bio⁃based degradable plastics industry to global leadership while addressing critical sustainability challenges.
