Materials and Properties
WEI Xuewei, ZHANG Xinwen, YE Haimu, XU Jun, GUO Baohua
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191 )
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Poly（ethylene succinate⁃co⁃ethylene oxalate） （PESOx） is an environmentally friendly， biodegradable polyester whose practical application is hindered by its slow crystallization kinetics following copolymerization. To address this drawback， we incorporated the organic nucleating agent dibenzoyl hydrazide sebacic acid （TMC⁃300） into PESOx via solution blending. While TMC⁃300 did not alter the crystal structure or thermal stability of the polymer， it remarkably enhanced its crystallization properties. The nucleating agent significantly increased the crystallization temperature and enthalpy， shortened the half⁃crystallization time， and accelerated the overall crystallization rate. Isothermal crystallization kinetics indicated that the efficacy of TMC⁃300 is concentration⁃dependent， with an optimal promotion effect observed at 1 wt%， suggesting a saturation concentration within the polymer matrix. Polarized optical microscopy confirmed a substantial increase in nucleation density， leading to smaller spherulite sizes and a faster crystallization rate. These findings demonstrate TMC⁃300's effectiveness in improving the processability of PESOx for commercial applications.
MENG He, JIANG Li, ZHANG Kai, YANG Mingbo
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65 )
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Poly（L⁃lactic acid） （PLLA） has attracted significant attention due to its environmental friendliness， processability， and mechanical properties. However， its low toughness and melt strength greatly limit its use as a blown film material. To solve this problem， we synthesized a graft copolymer， poly（vinyl alcohol） （PVA）⁃g⁃poly（D⁃lactic acid） （PDLA）， via the reaction of PDLA with PVA. This copolymer was then blended with PLLA/PVA using both direct and masterbatch melt blending methods. The crystallization behavior， rheological properties， relaxation behavior， and impact properties of the resulting blends were further investigated. The results indicated that， compared to the direct method， the masterbatch method produced blends with more and smaller stereo⁃complex crystals. This enhanced the melt strength， improved the relaxation behavior （increasing the characteristic relaxation time at 180 °C）， and induced clear strain hardening in extensional rheology. Additionally， the masterbatch blends exhibited superior impact toughness， with an impact strength of 6.03 kJ/m². This value is 3.8 times and 2.5 times higher than that of pure PLLA and the direct⁃method blend， respectively.
ZHENG Xinyuan, HUANG Xiao, YAN Guangming, ZHANG Gang, YANG Jie
Abstract (
68 )
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Semi⁃aromatic polyamides combine the desirable properties of both aromatic and aliphatic polyamides. In this study， a novel difluorobenzamide monomer， N，N’⁃（1，4⁃Piperazinediyldi⁃3，1⁃propanediyl） bis（4⁃fluorobenzamide） （FDC⁃200）， was synthesized via a facile interfacial reaction between 1，4⁃bis（3⁃aminopropyl）piperazine and 4⁃fluorobenzoyl chloride. A series of polyamides incorporating piperazine rings were subsequently prepared from this monomer through nucleophilic substitution polymerization. The chemical structures of the monomer and polymers were confirmed by FTIR and ¹H⁃NMR spectroscopy. These novel polyamides exhibited outstanding thermal properties， with glass transition temperatures ranging from 149.0 to 171.4 ℃ and a 5 % weight loss temperature exceeding 385 ℃. The incorporation of a diphenyl sulfone moiety was found to significantly enhance multiple material properties. Specifically， it improved tensile strength （exceeding 60 MPa）， increased hydrophobicity （water absorption as low as 3.7 % for sample SPAS⁃50）， and enhanced solubility， thereby broadening processability. Furthermore， the diphenyl sulfone structure imparted excellent flame retardancy， with sample SPAS⁃50 achieving a UL 94 V⁃1 rating. This work demonstrates a promising strategy for developing high⁃performance semi⁃aromatic polyamides with a versatile property profile.
HOU Qinzheng, LIU Wenlong, LI Changjin, QIN Liu, DING Yumei, LI Haoyi, YANG Weimin, HOU Zhengyuan
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69 )
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Low⁃density polyethylene （PE⁃LD） microfiber membranes are promising materials for medical， protective， and construction applications due to their corrosion resistance， hydrophobicity， and flexibility. However， conventional manufacturing processes face limitations. This study introduces a novel method for producing PE⁃LD membranes using supercritical carbon dioxide （SC⁃CO₂） as a plasticizing agent in a melt⁃blowing process. We systematically investigated the effects of key process parameters， including SC⁃CO₂ impregnation， hot air temperature， hot air flow rate， and metering pump speed， on the fiber morphology， crystallization behavior， and resulting properties. The results indicated that SC⁃CO₂ treatment， elevated hot air temperature， increased air flow， and reduced pump speed all contributed to a significant reduction in fiber diameter， achieving an average of 3.88 µm. Furthermore， SC⁃CO₂ and higher temperatures enhanced crystallinity. The optimized membrane exhibited excellent performance after hot⁃pressing： a filtration efficiency of 72.9 % with a remarkably low⁃pressure drop of 51.4 Pa， tensile strength of 4.5 MPa， and elongation at break of 30 %. This work establishes the SC⁃CO₂⁃assisted melt⁃blowing process as a highly effective and novel strategy for manufacturing high⁃performance PE⁃LD microfiber membranes with tunable properties.
SHI Liqiang, JIANG Zhenchun, HAO Weigang, GAO Wentao, MAO Lei, SHANG Weiwei, WANG Yingsai
Abstract (
63 )
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This study investigates the effect of reed powder particle size and morphology on the mechanical properties of polylactic acid （PLA） composites. The impact strength and flexural modulus were optimized at a particle size of 50 μm， achieving notched Izod impact strength of 3 kJ/m² at 23 °C and a flexural modulus of 3 690 MPa. Conversely， the 20 μm particles yielded the poorest performance. Furthermore， the use of a reed masterbatch （pre⁃compounded with white oil） was explored as a strategy to enhance processability. While the masterbatch effectively improved the melt flow rate of the composite， it resulted in a trade⁃off： impact performance increased compared to composites with directly added reed powder， but flexural strength decreased. The flexural modulus， however， exhibited a more pronounced increase. The investigation of masterbatch loading （10~30 wt%） demonstrated that increasing content led to higher density and flexural modulus， but reduced bending and tensile strength. Scanning electron microscopy of impact fracture surfaces indicated strong interfacial adhesion between the reed powder and the PLA matrix， confirming the potential of reed as a viable bio⁃filler for enhancing specific properties of PLA composites.
NI Jia, CHEN Zhangcheng, DUAN Kaige, CHEN Xiaodie, HU Yixuan, MEI Zhenwei, ZHOU Chaoxi, YU Dongming
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69 )
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This study developed a thermally conductive and heat⁃resistant polyethylene （PE） pipe through the melt blending and extrusion of PE with graphite. The effect of graphite content on the thermal conductivity was systematically investigated， and the resulting hydrostatic and mechanical properties were evaluated. The results indicated that an optimal loading of 12 phr of 300⁃mesh graphite yielded a composite with a thermal conductivity of 0.73 W/（m·K）， significantly enhancing the base polymer's heat transfer. Crucially， the composite pipe retained excellent pressure resistance， successfully passing standard hydrostatic tests at 20 °C for 1 h and at 95 °C for 22 h， 165 h， and 1000 h. This work confirms that graphite is an effective filler for fabricating PE pipes suitable for low⁃to⁃medium⁃temperature heat transfer applications without compromising mechanical integrity.
LI Xinyu, LU Shulai, WANG Liwei, XU Chao, NIU Jingpeng, MA Xiaokun
Abstract (
98 )
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To enhance the compatibility of polycarbonate （PC）/acrylonitrile⁃butadiene⁃styrene （ABS） blends， a modified ABS was synthesized via emulsion grafting polymerization with glycidyl methacrylate （GMA）. This GMA⁃modified ABS was subsequently melt⁃blended with PC. The epoxy groups of GMA were found to react effectively with the terminal hydroxyl and carboxyl groups of the PC chains， serving as a compatibilizer at the polymer interface. This reaction significantly improved the miscibility between the two phases. The optimal mechanical properties were achieved with a GMA loading of 10 g， resulting in a PC/ABS alloy with notch impact strength of 55.5 kJ/m² and elongation at break of 70 %. These values represent an 18 % increase in impact strength and a 46 % improvement in ductility over the uncompatibilized control blend. This work demonstrates an effective reactive compatibilization strategy for developing high⁃performance PC/ABS alloys.
CHEN Fei, LI Haodong, YU Min, HUA Haitao, LI Qingzhou, DONG Chunfa, XU Lei, WANG Zhiyong, HE Wuqing, YU Shengrui
Abstract (
71 )
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This study aims to optimize the microcellular injection molding （MIM） process for producing polymer components with uniform cell structure and enhanced mechanical properties. Using a combination of single⁃factor and orthogonal experimental designs， the effects of melt temperature， injection velocity， supercritical fluid （SCF） concentration， injection pressure， and nano-silica （SiO₂） content on cellular morphology and mechanical performance were systematically investigated. Matrix analysis was employed for multi⁃objective optimization based on cell diameter， cell density， tensile strength， and flexural strength. Results show that SCF concentration most significantly affects cellular structure， reducing cell diameter and increasing cell density with increasing concentration. Injection velocity has the greatest impact on mechanical properties， causing tensile strength to first decrease and then increase， while flexural strength decreases monotonically. The optimized process yields components with a cell diameter of 36.82 μm， cell density of 1.40×10⁶ cells/cm³， tensile strength of 19.69 MPa， and flexural strength of 36.49 MPa. These represent a 79.27 % reduction in cell diameter， an 8 135.29 % increase in cell density， and improvements of 39.94% in tensile strength and 12.87 % in flexural strength over pre⁃optimized values. Furthermore， all four metrics are enhanced by 1.47 %， 3.70 %， 3.09 %， and 0.69 %， respectively， compared to the best orthogonal experimental result.
SUN Jingru, CHEN Yang, YANG Xiangchun, JI Hui, WANG Li, DOU Hongxing
Abstract (
67 )
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This study compares the properties of microporous membranes fabricated from two domestic polytetrafluoroethylene （PTFE） resins with different molecular weights against two commercial benchmarks （Daikin F⁃106 and F⁃104C）. The influence of molecular weight on the microscopic morphology， thermomechanical properties， and mechanical performance of the stretched membranes was systematically investigated. The results indicated a strong structure⁃property relationship： the high molecular weight （HMW） PTFE resin facilitated the formation of a microstructure characterized by short fibers and small junctions. This structure yielded a membrane with a small pore size （0.22 μm）， high tensile strength （7.1 MPa）， but lower air permeability. Conversely， the low molecular weight （LMW） resin produced long fibers and large junctions， resulting in a membrane with a larger pore size （0.71 μm）， higher gas permeability ［33 L/（m²·s）］， and lower strength （3.3 MPa）. Furthermore， crystallinity analysis revealed that the HMW membrane had a lower crystallinity （69.72 %） compared to the LMW membrane （82.82 %）， suggesting greater crystal structure damage and weaker recrystallization ability during processing. These findings demonstrate that molecular weight is a critical parameter for tailoring PTFE microporous membranes for specific applications， with HMW resins favoring small⁃pore， high⁃strength membranes and LMW resins enabling high⁃permeability variants.
LIU Zhongping, XIAO Yinhe, GE Huijun
Abstract (
80 )
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This study investigates the root cause of cracking in the screw areas of a polycarbonate （PC） connector assembled within a device. A combination of analytical techniques， including differential scanning calorimetry， thermogravimetric analysis， gas chromatography⁃mass spectrometry （GC⁃MS）， and Fourier⁃transform infrared spectroscopy， was employed to compare cracked and normal samples. GC⁃MS analysis identified dibutyl phthalate （DBP）， a plasticizer， exclusively in the cracked components. The source of the DBP was traced to a polyvinyl chloride （PVC） soft tube installed through the connector. Hansen solubility parameter analysis confirmed a high affinity between DBP and PC （with a relative energy difference， RED， of 0.72）， indicating DBP's capability to solubilize and plasticize the PC matrix. The failure mechanism was identified as environmental stress cracking （ESC）： DBP migrated from the PVC tube into the PC housing， reducing its cohesive strength and enabling brittle fracture initiation under the stress concentrated at the screw threads. This case provides a classic example of ESC and highlights the critical need for compatibility screening between adjacent polymer components and their additives.
SU Yuhang, LU Xiuqiang, MAO Jianquan, YIN Wanglin, LIU Xiang, KE Junmu, LIN Yuanzhi
Abstract (
67 )
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This study developed a novel anaerobic biodegradable polypropylene （PP） film by incorporating ethyl acrylate⁃grafted chitin via a three⁃layer cast co⁃extrusion process. The successful grafting of ethyl acrylate onto chitin， confirmed by nuclear magnetic resonance， Fourier⁃transform infrared， and Raman spectroscopy， significantly enhanced its thermal stability， increasing the decomposition temperature to 340 °C. The modified chitin was compounded into a masterbatch with PP. The incorporation of 3 % monoglycerides as a compatibilizer improved the fluidity and dispersion of the masterbatch containing 10 % chitin. In the final extruded films， modified chitin content at or below 1.5 % acted as a heterogeneous nucleating agent， increasing the crystallinity， melting point， and crystallization rate of PP. At a 2 % loading， the film exhibited optimal tensile strength of 12.8 MPa， although elongation at break decreased. This formulation also demonstrated excellent optical properties， with a light transmittance of 87.6 % and haze of 4.6 %， surpassing the clarity requirements of the national BOPP film standard. Crucially， anaerobic composting tests revealed that films with 1.5 % modified chitin achieved an average biodegradation rate of 9.19 % over 56 days， confirming the effectiveness of this approach in enhancing the anaerobic biodegradability of PP films without severely compromising their mechanical and optical properties.
Processing and Application
JIN Qingping, WU Bo, YI Jianming
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56 )
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This study experimentally investigated the effect of end restraint conditions on the axial compressive performance of concrete⁃filled glass fiber⁃reinforced polymer （GFRP） tube long columns. Monotonic axial compression tests were conducted on specimens under three distinct boundary conditions： both ends fixed， one end fixed and one end hinged， and both ends hinged. The failure modes， load⁃strain responses， ultimate bearing capacity， and lateral displacement were systematically analyzed. The results indicated that there was a transition in failure mode from a brittle end failure in fixed⁃fixed columns to global bending instability in columns with hinged ends. The fixed⁃fixed configuration demonstrated the highest ultimate bearing capacity and ductility. In contrast， the ultimate bearing capacity for the one⁃end⁃hinged and both⁃ends⁃hinged configurations decreased by 23.9 % and 25.5 %， respectively， while their ultimate axial strains were reduced by 53.4 % and 65.8 %. The lateral displacement was most pronounced in the both⁃ends⁃hinged configuration， with its peak value at ultimate load being 41.4 % and 35.8 % higher than that of the fixed⁃fixed and fixed⁃hinged configurations， respectively. The experimental data correlated well with an ideal buckling curve model. Furthermore， predictions from an existing stability factor model for ultimate bearing capacity showed good agreement with the test results. These findings underscore the critical importance of end restraint conditions in the design and stability analysis of concrete⁃filled GFRP long columns.
GUAN Tianmin, LI Xin, GUO Zefang, WU Guanying, ZHAI Yun
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73 )
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This study investigates the tensile behavior of C⁃shaped thin⁃walled structural parts fabricated via unsupported fused deposition modeling （FDM）. Combining finite element simulation with static tensile testing of ABS and PC specimens， the influence of intrinsic structures on mechanical properties， stress distribution， and failure mechanisms was systematically analyzed. An orthogonal experimental design， fracture morphology analysis， and three⁃factor ANOVA were employed to evaluate the effects of geometry. Key findings established a minimum allowable unsupported printing angle of 16.53 °. Among the geometries tested， concave structures exhibited the highest elastic modulus. An optimal wall thickness of 5 mm was identified， outperforming 3⁃ and 4⁃mm configurations. While the slope of the structure had no significant effect on the elastic modulus， the height （and consequently the rotation radius） was a critical factor. This difference in rotation radius dictated the failure location： fractures initiated at smaller radii in straight and convex structures， but at larger radii in concave structures. This study provides crucial design guidelines for optimizing the mechanical performance of unsupported FDM thin⁃walled structures.
LI Yanjun, LI Tong, JIN Miao, YIN Duoyuan, LIU Rui
Abstract (
71 )
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The true impact rate （TIR）， a key metric for assessing the impact resistance of thermoplastic pipes， is defined as the ratio of failures to the total number of impacts in a test batch. This paper proposes a rigorous statistical methodology for TIR analysis by modeling it as a binomial parameter. A large⁃sample theory was employed to construct confidence intervals using both normal and Poisson approximations. Furthermore， hypothesis testing procedures was derived， presenting the results in readily applicable critical value tables and charts. This framework enables rapid and reliable assessment of TIR data， offering a standardized approach that streamlines quality control in industrial settings and provides a valuable reference for impact testing protocols across materials science.
ZHANG Xu, MA Hua
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63 )
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This study conducts a systematic analysis of the global patent landscape for biodegradable occluders. By examining application trends， major applicants， and key technology distributions， we map the technological evolution and competitive dynamics of this field. The analysis identifies leading innovators， critical patented technologies， and associated commercial products， providing a clear technology roadmap.
Standard and Test
LI Nanyang, XU Mei, WU Jiangang, LI Xiaofeng
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51 )
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The quality of retort pouch plastic composite films is critical to food safety. However， the dominant Chinese standards， GB/T 10004—2008 and GB/T 21302—2007， were published over fifteen years ago. These standards are now misaligned with international benchmarks and contain internal inconsistencies in key performance indicators， failing to meet modern health， safety， and environmental requirements for food⁃contact materials. This study employs a standardized digital platform to conduct an intelligent retrieval and big data analysis of relevant domestic and international product standards. Through a systematic comparison of standard indicators， we summarized the current development status and elucidated the similarities and differences between Chinese， Japanese， and other international standards. The findings aim to provide a data⁃driven reference for the comparative analysis of standard indices， the revision of outdated Chinese standards， and the overall improvement of retort pouch product quality and safety.
Plastic and Environment
PANG Yue, FU Ye, WENG Yunxuan
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72 )
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The urgent need to control global plastic pollution has driven the vigorous development of biodegradable plastics as a solution to prevent waste at the source. Poly（butylene adipate⁃co⁃terephthalate） （PBAT）， renowned for its flexibility， impact resistance， and biodegradability， has emerged as one of the most widely used polymers in this class. It is extensively applied in producing biodegradable films， packaging materials， and disposable tableware. This review comprehensively summarizes the current progress in PBAT biodegradation. The known microbial strains and enzymes capable of degrading PBAT were categorized， and their respective degradation efficiencies were evaluated. The key environmental and material factors influencing the degradation rate were discussed， and the underlying microbial mechanisms were elucidated. Finally， critical challenges and future directions were addressed， including the need for standardized evaluation methods， the development of specialized microbial consortia， and the exploration of efficient enzymatic systems for large⁃scale bioremediation applications.
QUAN Shumiao, ZHANG Zhe, YU Dan, DU Runping
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52 )
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Polymer⁃based radiative cooling materials represent a promising technology for passive thermal management， leveraging spectral control to achieve substantial energy savings and multi⁃scenario applicability. This review elucidates the fundamental principles of radiative cooling and expounds on the unique advantages of electrospinning technology for preparing high⁃performance cooling membranes. The critical strategies to optimize cooling efficiency through material choice， nano⁃micro structural design， and membrane architecture was emphasized. Furthermore， the applications of electrospun radiative coolers in smart textiles， personal equipment， and energy⁃efficient buildings were examined. The review concluded by identifying prevailing challenges and prospective research directions for scalable manufacturing， thereby addressing the path toward industrialization.
WANG Qiong, XU Fang, WENG Yunxuan
Abstract (
57 )
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The escalating production and application of polylactic acid （PLA） have intensified the need for efficient recycling methods for its post⁃consumer waste. This review comprehensively summarized recent advancements in PLA synthesis， depolymerization， and chemical recycling. Various depolymerization techniques were critically analyzed with a focus on their reaction mechanisms， catalytic systems， and the resulting product streams. Furthermore， the advantages and limitations of each chemical recycling pathway were evaluated， and future research directions and challenges in establishing a circular economy for PLA were discussed.
Machinery and Mould
ZHAO Liping, YANG Zhanpeng, CHEN Yinghua, CHENG Yu, HUANG Qiye, QIN Ruiliang
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58 )
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This study presents the design of a high⁃precision injection mold for a complex automobile storage box component. To meet the part's strict technological requirements， a single⁃cavity structure and a tailored gating scheme were adopted， complemented by a dedicated mold balancing device for smooth operation. Two design schemes were compared to determine the optimal parting surface location， resulting in a two⁃parting⁃plane structure and a long⁃stroke， two⁃stage core⁃pulling system. The first parting plane （PL1） offers two key advantages： firstly， it facilitates the early removal of the fixed mold core insert to prevent the part from adhering to the stationary side； secondly， it employs an angled pin mechanism for the initial breakaway of the core to overcome high pellet packing forces. A hydraulic cylinder then executes a second core⁃pulling stage to achieve reverse withdrawal. This approach guarantees cylinder stability during the final ejection phase， leading to marked improvements in both production efficiency and product quality.
Review
ZHAO Lin, YANG Gaopin, YANG Weimin
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67 )
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This paper comprehensively reviews the current understanding of residence time distribution （RTD） within the plasticizing system of screw extruders. The core principles and characteristics of RTD were explained， and the primary influence factors were discussed. An overview of contemporary measurement techniques was also provided. The review highlighted the role of RTD as a robust indicator of mixing uniformity during extrusion and underscored its broad application potential in novel extrusion processes. Ultimately， investigating RTD offers innovative approaches for driving the extrusion industry toward greater precision and intelligent manufacturing.
QIN Huai, YANG Kuan, WU Jing, WANG Shulei, YANG Chenxin
Abstract (
66 )
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This review summarizes recent advancements in the development of photo⁃crosslinked methacrylic acid （MA） hydrogels for wound repair. The review began by detailing the common materials used to fabricate these hydrogels. Furthermore， the application of photo⁃crosslinked MA hydrogels was discussed， with a specific focus on their efficacy in promoting wound healing through controlled drug delivery. This analysis highlights the significant potential of these smart materials in advanced wound management.
LI Yan, WANG Xinyan, ZHUANG Chuanlong, CHEN Jie, LIU Ye
Abstract (
57 )
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Polymer⁃based radiative cooling materials represent a promising technology for passive thermal management， leveraging spectral control to achieve substantial energy savings and multi⁃scenario applicability. This review elucidates the fundamental principles of radiative cooling and expounds on the unique advantages of electrospinning technology for preparing high⁃performance cooling membranes. The critical strategies to optimize cooling efficiency through material choice， nano⁃micro structural design， and membrane architecture was emphasized. Furthermore， the applications of electrospun radiative coolers in smart textiles， personal equipment， and energy⁃efficient buildings were examined. The review concluded by identifying prevailing challenges and prospective research directions for scalable manufacturing， thereby addressing the path toward industrialization.
