Materials and Properties
WANG Shuo, YUAN Wenbo, CHENG Yichong, ZANG Yuntao, LENG Dongliang, LI Haiyan, ZHAO Ling, HU Dongdong
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196 )
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Polypropylene （PP） with varying degrees of branching was prepared using dicumyl peroxide （DCP） as an initiator and tetramethyl thiuram monosulfide （TMTM） combined with pentaerythritol triacrylate （PETA） as dual monomers. The modified PP was foamed via supercritical CO₂ molding， and the influence of branching degree on molecular weight， molecular weight distribution， melt crystallization， rheological behavior， and foaming performance was systematically investigated. Results indicated that the crystallization temperature of PP gradually increased with higher branching degrees， while crystallinity degree decreased compared to linear PP. Enhanced branching also improved melt viscoelasticity， prolonged relaxation time， and intensified shear thinning and strain hardening effects. Furthermore， the foaming temperature window expanded by 12 ℃. Under optimal conditions （15 MPa CO₂， 152 ℃）， the modified PP achieved a maximum expansion ratio of 30⁃fold， exhibiting a more uniform cell structure. The foam with a 25⁃fold expansion ratio demonstrated superior mechanical properties， with compression and tensile moduli reaching （18.94±0.55）MPa and （3.51±0.06）MPa， respectively， outperforming the E02ES™ foam at the same expansion ratio.
NIU Kai, ZHANG Run, LIU Mingfei, FU Chenchao, XUE Ping, WU Jiajun
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66 )
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In this study， the visco⁃elastic⁃plastic deformation behavior of ultra⁃high⁃molecular⁃weight polyethylene （PE⁃UHMW） were systematically investigated under thermo⁃mechanical coupling conditions. Through comprehensive mechanical characterization including elastic modulus measurements， creep tests， and stress relaxation analysis， the temperature⁃dependent evolutions of key parameters， including tensile modulus， viscosity coefficient， and relaxation time， were quantified. Experimental results indicated a significant thermo⁃sensitive behavior， with the tensile modulus decreasing from 134.26 to 20.96 MPa， viscosity coefficient from 325.61 to 224.66 GPa·s， and relaxation time from 937.83 to 830.29 s as temperature increased from 50 to 120 °C. A novel parallel physical model combining spring， Kelvin， and viscous pot elements was developed to accurately describe the deformation mechanisms under constant strain conditions. This model provides fundamental insights into the complex visco⁃elastic⁃plastic behavior of PE⁃UHMW， establishing quantitative relationships between thermal conditions and mechanical response.
YAN Wanhua, ZHAI Ming, RUAN Shilun, SHEN Changyu
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113 )
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This study investigated the crazing mechanism in glassy polyethylene using coarse⁃grained molecular dynamics simulations with the LAMMPS package. A bead⁃spring model was employed to examine the microstructural evolution and stress⁃strain behavior under tensile deformation at varying strain rates. The analysis included quantification of entanglement density along the original chain paths and characterization of entanglement network evolution through energy landscape mapping. Results indicated significant strain rate dependence in the crazing initiation process. The craze growth mechanism was demonstrated to be fundamentally governed by chain disentanglement. Furthermore， temperature⁃dependent simulations revealed a self⁃healing capability of crazes at elevated temperatures. These findings provide molecular⁃level insights into the deformation mechanisms of glassy polymers under mechanical stress.
LIU Wei, PEI Wenyu, FU Zhongyu
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99 )
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In this study， the effects of thermal treatment on polyacrylonitrile （PAN） powder and its subsequent impact on membrane properties were investigated. PAN powders were heat⁃treated under air/vacuum conditions， enabling the preparation of a series of PAN membranes. The thermal treatment promoted both intramolecular and intermolecular cross⁃linking while facilitating the formation of hydrophilic imide structures. This modification effectively exhibited the phase separation rate of PAN solutions in water， yielding membranes with enhanced hydrophilicity and density. Optimal performance was achieved with membranes prepared from PAN powders treated at 140 °C for 2 h in air. The resulting 9 wt% PAN film presented a water contact angle of 47 ° （4.8 ° reduction） and dry film tensile strength of 5.591 MPa （132 % increase） compared to untreated controls. Furthermore， these membranes demonstrated excellent separation performance， with water flux reaching 1 500 L/（m²·h） and n⁃hexadecane rejection of 99.4 %. These findings highlight the significant potential of thermal pretreatment for improving PAN membrane properties for separation applications.
CHEN Xi, DONG Jinming, WANG Yatao, BAI Ruyi, SHI Tao, LIU Huan, MA Xiaofeng, WANG Xiaodong
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135 )
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In this study， polyoxymethylene （POM）/cellulose nanofiber （CNF） composite aerogels were fabricated via vacuum freeze⁃drying， and the influence of fiber length on their structure and properties was systematically investigated. Nano⁃silica （SiO₂） was incorporated at varying mass percentages to produce POM/CNF/SiO₂ composite aerogels， and their radiative cooling performance was evaluated. Temperature variations of the aerogels were monitored under direct sunlight and shaded conditions on a clear day. Results indicated that the POM/CNF aerogel prepared with 1 mm fibers achieved a maximum sub⁃ambient cooling of 8.7 ℃ under direct sunlight. With the addition of nano⁃SiO₂， the composite aerogel exhibited enhanced cooling performance， reaching a maximum temperature reduction of 12.2 ℃. Under shaded conditions， the temperature drops were 2.5 and 1.6 ℃ for the POM/CNF and POM/CNF/SiO₂ composite aerogels， respectively. Notably， the optimal incorporation of nano⁃SiO₂ significantly improved solar reflectance （up to 92.44 %） and compressive strength while maintaining high infrared emissivity （82.56 %） and low thermal conductivity ［0.048 W/（m·K）］. These findings indicate that POM⁃based composite aerogels exhibit exceptional radiative cooling performance and favorable mechanical properties， offering a viable strategy for energy⁃efficient cooling applications and the development of high⁃performance radiative cooling textiles.
LIN Minghua, WANG Hua, GUO Jianbing, ZHENG Bin, WANG Yao
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119 )
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In the present study， the effects of varying proportions of epoxy soybean oil （ESO）/tung oleic anhydride （TOA） gel on the properties of polylactic acid （PLA）/lignin （LM） composites were investigated. The mechanical properties， crystallization behavior， dynamic mechanical performance， and thermal stability of the composites were characterized using scanning electron microscopy， dynamic mechanical analysis， thermogravimetric analysis， and rotational rheometry. The results indicated that the ESO/TOA gel was dispersed effectively in the PLA matrix， reacting with both PLA and lignin to improve compatibility and toughness. The gel enhanced molecular chain mobility， increasing composite crystallinity， though it slightly reduced thermal stability. The fracture elongation of the composites rose significantly with higher TOA content， increasing from 6 % （pure PLA） to 32 %. At an ESO∶TOA ratio of 5∶5， the gel particles achieved optimal dispersion， yielding the best overall performance， including an impact strength of 4.1 kJ/m².
REN Baixia, CHEN Xuelian, LI Yafei, ZHANG Wenxiu, GUO Chuangyue
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121 )
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The modification of polyethylene （PE） and maleic anhydride （MAH）⁃grafted PE were investigated using the peroxide crosslinking agent 1，3⁃bis（tert⁃butylperoxyisopropyl）benzene （BIPB）. The crosslinked materials were systematically characterized through FTIR spectroscopy， surface oxygen content analysis， mechanical testing， and thermal analysis. Results revealed distinct oxygen sources in crosslinkable versus crosslinked materials： while MAH and BIPB contributed oxygen in uncrosslinked powders， only MAH⁃derived oxygen remained after crosslinking due to BIPB decomposition. Increasing crosslinking degree led to MAH enrichment at material interfaces and the formation of distinctive interfacial morphology， accompanied by a decrease in crystallization onset temperature from 116.99 to 113.17 °C. As BIPB content increased from 0.1 to 0.5 phr， significant property changes were observed as follows： crystallinity decreased from 49.4 % to 42.2 %， tensile strength declined from 13.2 MPa to 11.1 MPa， and bonding strength reduced from 4.01 MPa to 3.53 MPa. These findings provide crucial insights into the structure⁃property relationships of peroxide⁃crosslinked PE systems， particularly regarding the competing effects of crosslinking density and crystallinity on mechanical performance.
XIE Wei, DENG Zhonghui, YAN Yu
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128 )
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In this study， a type of bilayer film was fabricated for monitoring minced pork freshness using raw or cooked purple sweet potato powders as the base material， combined with sodium alginate， titanium dioxide， and citric acid， through a layer⁃by⁃layer self⁃assembly technique. Eight distinct film formulations were comprehensively characterized for their structural， optical， mechanical， antioxidant， and ammonia⁃responsive properties， including X⁃ray diffraction， scanning electron microscopy， water vapor permeability， and controlled release performance. Among these， the STNPR film demonstrated optimal overall performance， exhibiting an opacity of 7.18 mm⁻¹， tensile strength of 2.93 MPa， elongation at break of 39.2 %， moisture content of 26.78 %， water vapor permeability of 0.000 3 g/（mm·d）， water solubility of 50.97 %， swelling ratio of 362.99 %， and DPPH radical scavenging activity of 56.79 %. When applied to monitor minced pork freshness， the STNPR film displayed a visible color transition from eggplant purple to dark eggplant purple and finally to blue⁃black， correlating with pork quality degradation. This colorimetric response provides a simple， reliable， and visually intuitive method for real⁃time freshness assessment， offering practical utility for consumers.
LIN Conglong
Abstract (
81 )
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In this study， the self⁃lubricating thermoplastic vulcanizate （TPV） materials for automotive applications were investigated， focusing on friction coefficient， substrate adhesion， and physical properties of various lubricant formulations. Experimental results demonstrated that TPV compounds incorporating 5.0 phr （parts per hundred rubber） of high⁃molecular⁃weight polydimethylsiloxane exhibited optimal performance， achieving a surface friction coefficient of ≤0.75 while maintaining excellent bonding strength and mechanical properties. These characteristics make the developed material particularly suitable for automotive glass trim applications， offering significant potential for improved performance in demanding decorative applications.
ZHENG Shilun, ZHOU Qiwei, LIU Bin, LIANG Xuzhi, YUAN Mingyuan
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145 )
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This study investigated the effects of hyperbranched polyester （HBP H202 and H204） surface modification on carbon nanotubes （CNTs） and their subsequent impact on waterborne unsaturated polyester （WUPR） composites. Successful grafting was confirmed through FTIR， XRD， and XPS characterization. Comparative analysis indicated that while unmodified CNTs slightly enhanced WUPR's mechanical properties， HBP⁃modified CNTs （CNTs H202 and CNTs H204） demonstrated superior performance. Notably， CNTs H204 showed the most significant mechanical improvement. SEM analysis confirmed better CNT dispersion in WUPR after HBP modification. Friction tests indicated that modified CNTs substantially reduced mass wear compared to both pure WUPR and unmodified CNT composites. DMA test results showed enhanced storage modulus and glass transition temperature， with CNTs H202 exhibiting particularly strong interfacial interactions due to its smaller molecular size and higher grafting density. These findings demonstrated that HBP surface modification effectively improved CNT dispersion and interfacial bonding in WUPR， leading to superior composite performance. This work provides valuable insights for developing high⁃performance WUPR composites and broadening their industrial applications.
Processing and Application
HAN Yusheng, YANG Jianjun, ZHENG Ying, WANG Yaxiao
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87 )
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To address the challenges of interfacial separation and poor tensile properties in discrete functional gradient substrates， this study proposed a novel substrate structure based on interface design. Using PDMS⁃based materials as an example， functional gradient flexible substrates were fabricated via extrusion⁃based 3D printing. Six distinct interface structures were evaluated for their tensile properties， with the island structure demonstrating the most effective suppression of interfacial delamination. Orthogonal experiments were conducted to optimize the island structure parameters， using tensile ratio as the key performance metric. The optimal configuration was determined as follows： 4 islands per unit length， an island⁃to⁃bridge length ratio of 1， a width ratio of 1.75， and an edge margin ratio of 0.07. The results indicated that the island structure significantly enhanced interfacial cohesion， improving the tensile ratio by 1.82 times compared to conventional designs.
XU Feng, LI Yingjie, YANG Juyi, LI Xuan, CHU Chenglin
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88 )
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In this study， the thermal oxidative aging behavior of polyethylene gas pipelines was investigated under combined high⁃temperature and mechanical loading conditions. A specialized experimental apparatus was developed to simulate aging under these operational stresses. The effects of external loading on mechanical properties， microstructure， and thermal characteristics were systematically evaluated using tensile testing， scanning electron microscopy， Fourier⁃transform infrared spectroscopy， and differential scanning calorimetry. Results demonstrated that prolonged high⁃temperature exposure led to decreased elongation at break and reduced oxidation induction time， while increasing both carbonyl index and material crystallinity. Notably， applied external loads significantly accelerated the aging process. At a 1 000 N load， the aging rate increased by factors of 1.8 （elongation）， 1.17 （carbonyl index）， and 1.3 （oxidation induction time） compared to unloaded samples. These findings quantitatively established the synergistic degradation effects of thermal and mechanical stresses on pipeline polyethylene， providing critical insights for material service life prediction and maintenance strategies.
LIU Yinglan, XIAO Jianhua, GAO Yanfeng, XU Shikang
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129 )
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In this study， a novel high⁃temperature， high⁃pressure gas⁃assisted 3D printing method was proposed to enhance interlayer bonding strength in polymer additive manufacturing. Using thermoplastic polyurethane （TPU） as a model material， the effects of this approach on the temperature field distribution， tensile strength， cross⁃sectional morphology， and surface chemistry of printed parts were systematically investigated. Experimental results indicated that the gas⁃assisted process achieved a uniform， elevated temperature field in TPU filaments， promoting effective interlayer fusion while maintaining low porosity （≤2 %）. This optimization leads to a 96 % improvement in tensile strength compared to conventional 3D printing methods. Furthermore， surface characterization confirmed that high⁃temperature oxygen exposure did not induce thermal oxidation or chemical degradation of the printed material. These findings established an effective strategy for significantly improving the mechanical performance of polymer 3D⁃printed components without compromising material integrity.
LYU Bingjin, YAN Feng, LI Junjie, BAO Lingchen, HUANG Kaiyong
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85 )
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This study investigated the adhesion mechanism between iron tailings and asphalt modified with anti⁃stripping agents. Three commercial anti⁃stripping agents （XT⁃1， PA⁃1， and ZL⁃16） were incorporated into 70# base asphalt to prepare modified binders. The road performance of iron tailings asphalt mixtures was evaluated， while surface free energy analysis and Fourier⁃transform infrared spectroscopy were employed to characterize the interfacial adhesion properties. Results indicated that all anti⁃stripping agents significantly enhanced mixture performance， with PA⁃1⁃modified asphalt showing the most notable improvements： 14.3 % increase in residual stability， 17.7 % enhancement in freeze⁃thaw splitting strength ratio， and 61.4 % improvement in high⁃temperature stability compared to the control. The surface free energy and chemical bonding analysis revealed the underlying mechanisms for the improved interfacial adhesion between iron tailings and modified asphalt.
LI Wei, TANG Pengfei, PAN Dong, SHI Tuo, MO Shubei
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89 )
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In this study， the burst pressure calculation methods for PVC⁃UH pipes were investigated through experimental and theoretical analysis. Burst tests were conducted on four types of small⁃to⁃medium diameter pipes to evaluate the applicability and accuracy of various burst pressure calculation theories. Based on the material characteristics of PVC⁃UH， a new calculation method was proposed using a plastic deformation criterion. The results indicated that conventional metal pipe formulas were unsuitable for PVC⁃UH pipes. When using nominal yield strength as the calculation parameter， the TSSY criterion， modified Nadai， Bailey⁃Nadai， Welling⁃Uebing， Turner， Bailey， ASME， Barlow series， maximum stress guidelines， maximum shear stress guidelines， and Zhu⁃Leis method are appropriate. For true breaking strength， the Tresca criterion， Marin⁃2， Svenson， Bohm， and API methods are recommended. The most accurate results were obtained using the average of nominal yield strength and true fracture strength. A 0.4 % residual strain failure criterion was proposed， which demonstrated through twofold elastic deformation analysis that PVC⁃UH pipes fail at 1.7 % circumferential strain. The derived plastic deformation⁃based formula shows excellent agreement with experimental data， providing reliable technical support and theoretical basis for PVC⁃UH pipe burst pressure calculation.
Additive
LI Zhiwei, QIAN Xiumin, ZHANG Lanlan, LIN Huazhen, DING Enen, QIN Yumei, LAI Chaokun
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In this study， a reliable gas chromatography⁃mass spectrometry method was developed for simultaneous determination of five novel flame retardants， including 4⁃tert⁃butylphenyl diphenyl phosphate （MDPP）， 2⁃ethylhexyltetrabromobenzoate （TBB）， bis（4⁃tert⁃butylphenyl）phenyl phosphate （DBPP）， tris（p⁃t⁃butylphenyl）phosphate （TBPP）， and bis（2⁃ethylhexyl）⁃2，3，4，5⁃tetrabromophthalate （TBPH）， in recycled plastics. The method employed ultrasonic⁃assisted methanol extraction， followed by separation on a DB⁃5HT capillary column （15 m×0.25 mm×0.10 μm） with temperature programming. Identification and quantification were performed using both full scan and selected ion monitoring modes with external standard calibration. The method demonstrated excellent linearity （R²>0.998） across a concentration range of 0.05~10 mg/L. Method validation showed detection limits of 0.12~0.18 mg/kg and quantification limits of 0.40~0.60 mg/kg. Average recoveries at three spiking levels （0.5， 20 and 100 mg/kg） ranged from 95.7 % to 106.4 %， with relative standard deviations （RSDs， n=7） between 0.2 % and 5.1 %， confirming the method's accuracy and precision for analyzing these emerging contaminants in plastic matrices.
Plastic and Environment
YANG Fan, HU Yihong, YANG Fayong, HU Bin, JING Hongjun, LI Haibin
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94 )
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This study investigated the application of modified waste polyethylene terephthalate （PET） pellets as an asphalt modifier for road construction. PET⁃modified asphalt was prepared with varying modifier contents （4.5 %~6.5 % by mass of base asphalt） and systematically evaluated. Comprehensive testing identified 6.0 % PET content as the optimal modifier content， demonstrating significant performance improvements： a 33.3 % reduction in penetration degree， 21.1 % increase in softening point， and decreased ductility compared to base asphalt. Subsequent mixture evaluation through rutting tests， low⁃temperature bending tests， water immersion Marshall tests， and freeze⁃thaw splitting tests revealed enhanced performance characteristics. The modified mixture exhibited 151.1 % greater dynamic stability， along with 5.6 % and 3.0 % improvements in residual stability ratio and freeze⁃thaw splitting strength ratio， respectively. While low⁃temperature crack resistance decreased marginally （5.3 % reduction in flexural tensile strength and 6.7 % in strain）， the results indicated that PET modification substantially improved high⁃temperature stability and water resistance of asphalt mixtures. This study validates the technical feasibility of using waste PET in road engineering while providing an effective recycling solution for plastic waste， contributing to sustainable infrastructure development.
NIU Zhong, WU Zunhong, DONG Haijun
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142 )
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In this study， a novel compound additive （DSAE） was developed through physical blending of decanedioic acid bis（benzoylhydrazide） （DSA） and erucamide， which was incorporated into recycled PA6 （rPA6） via melt blending to fabricate high⁃performance composites. Comprehensive characterization revealed that erucamide preserved DSA's molecular structure while DSA functioned as an effective heterogeneous nucleating agent， elevating the crystallization temperature， crystallinity degree， and crystallization rate of rPA6. The DSAE formulation further enhanced these effects through improved matrix dispersion. Both additives significantly improved tribological and mechanical properties， with DSAE demonstrating optimal performance： 28.4 % reduction in friction coefficient， along with 51.6 % and 16 % increases in notched impact strength and flexural strength， respectively， compared to commercial badminton net material. The rPA6/DSAE composite achieved an exceptional balance of wear resistance， stiffness， and toughness， making it particularly suitable for high⁃dynamic⁃load applications. This work pioneers a sustainable “net⁃to⁃net” recycling strategy， transforming waste fishing nets into high⁃value sports equipment materials while establishing a circular economy paradigm for engineering plastics.
ZHANG Mengling, LUO Yadan, LIU Mingchang, WANG Mujie, PENG Zheng, WU Yajun
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94 )
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This study evaluated regulatory enforcement requirements for former hexabromocyclododecane （HBCD） producers and downstream enterprises in the plastics industry. By analyzing key regulatory enforcement priorities and identifying critical market supervision targets， the review paper provides technical and policy support for developing a robust market supervision framework. The review aims to facilitate compliance with international chemical conventions， ensuring effective phase⁃out implementation and sustainable chemical management in the plastics sector.
Machinery and Mould
YANG Fan, ZHANG Weihe
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125 )
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To meet the structural requirements of a car rearview mirror bracket， characterized by high dimensional accuracy， complex geometry， large lateral buckle size， and directional tilt， a large， high⁃precision， and complex injection mold was designed. In this mold， a fixed⁃mold spring block mechanism was used to prevent sticking between the fixed mold and molded parts. A near⁃conformal water temperature control system was designed to eliminate weld lines and part deformation. An increased slider safety distance was designed to avoid collisions during demolding. The mold achieved a successful first trial， operating smoothly in production with molded parts meeting MT2 precision （GB/T14486—2008）. The injection cycle was reduced by 10 % to 30 s， demonstrating the mold’s advanced， scientific， and innovative design.
Review
YAN Lijun
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This paper comprehensively reviewed the novel steel⁃fiber⁃reinforced polyethylene composite pipe， focusing on its structural characteristics， manufacturing processes， and connection technologies. The paper also analyzed the current production status and application landscape of this composite pipe in China， while critically discussing existing challenges in its development. Furthermore， the promising future applications and growth potential for this advanced piping material were highlighted. This review paper provides valuable insights for both industry practitioners and researchers working with reinforced polymer composites for piping systems.
