Polymer Testing最新文献_第3页

Interfacial-engineered 3D nano-carbon networks for synergistic enhancement of thermal–electrical transport and anisotropic heat dissipation 界面工程三维纳米碳网络协同增强热电传输和各向异性散热

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-12-12 DOI: 10.1016/j.polymertesting.2025.109078

Lide Yang , Sisi Chen , Jia Chen , Jianmin Yuan , Guowen He , Hui Fu

Despite recent advances in flexible thermal management materials, achieving simultaneous high thermal conductivity (k) and mechanical flexibility remains fundamentally challenging. A bioinspired method is demonstrated through the design of sandwich-structured cellulose nanofiber (CNF) composite films incorporating high-loading functionalized graphene nanosheets (GNS) and carbon nanospheres (CSs). CNF-GNS-MWCNT/CMC-CS/CNF-GNS-MWCNT composite (CNFGs) films are prepared by vacuum-assisted assembly followed by thermal lamination and show sandwich-like composite structure. In this composite film, a continuous three-dimensional thermal/conductive network—where vertically aligned CSs bridge horizontally organized GNS layers—is constructed, achieving superior in-plane/through-plane k (10.63/3.02 W/m·K) and efficient thermal management capabilities, effectively mitigating heat accumulation in practical applications (e.g., reducing LED chip temperatures by ∼23 °C). Furthermore, the superior Joule heating performance of CNFGs is demonstrated due to their high electrical conductivity (σ, 762 S/m in-plane; 265 S/m through-plane), with a saturated temperature of 113 °C achieved at 2.8 V, highlighting their potential for advanced thermal management and electrothermal conversion applications. Concurrently, thanks to surface-functionalized GNS/CS serving as dynamic anchoring sites for CNF chains, the composite films achieve long-range interconnectivity, retaining excellent mechanical flexibility (∼3.5 % elongation at break at 60 wt%, approaching pure CNF) while preserving over 97 % of the original k even after 1000-fold folding cycles. This work presents a simple yet effective strategy for designing high-performance flexible conductive/heat conduction polymer composites, offering new insights into interface-engineered carbon-based hybrid materials for next-generation electronics and energy devices.

尽管柔性热管理材料最近取得了进展，但同时实现高导热系数(k)和机械柔韧性仍然具有根本性的挑战性。通过设计含有高负载功能化石墨烯纳米片（GNS）和碳纳米球（CSs）的三明治结构纤维素纳米纤维（CNF）复合膜，展示了一种生物启发方法。采用真空辅助组装-热叠层法制备CNF-GNS-MWCNT/CMC-CS/CNF-GNS-MWCNT复合膜，呈现三明治状复合结构。在这种复合薄膜中，构建了一个连续的三维热/导电网络，其中垂直排列的CSs桥接水平组织的GNS层，实现了卓越的面内/通面k （10.63/3.02 W/m·k）和高效的热管理能力，有效地减少了实际应用中的热量积累（例如，降低LED芯片温度约23°C）。此外，由于其高电导率（σ，平面内762 S/m；平面内265 S/m），在2.8 V下达到113°C的饱和温度，CNFGs具有优越的焦耳加热性能，突出了其在先进热管理和电热转换应用方面的潜力。同时，由于表面功能化的GNS/CS作为CNF链的动态锚定位点，复合膜实现了远距离互连，保持了优异的机械柔韧性（在60 wt%的断裂时延伸~ 3.5%，接近纯CNF），即使在1000次折叠循环后仍保留了97%以上的原始k。这项工作为设计高性能柔性导电/导热聚合物复合材料提供了一种简单而有效的策略，为下一代电子和能源设备的界面工程碳基混合材料提供了新的见解。

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引用次数: 0

Assessment of plastics’ biodegradability under soil conditions based on modified biodegradability testing methods 基于改良生物降解性试验方法的土壤条件下塑料生物降解性评价

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-12-12 DOI: 10.1016/j.polymertesting.2025.109076

Geun-Yong Ham , Tomonori Ishigaki , Satoru Ochiai , Masato Yamada , Kazuei Ishii

Plastics are vital but pose environmental challenges, particularly in soil ecosystems due to agricultural use and improper disposal. Biodegradable plastics (BPs) offer a potential solution, yet their real-world degradation remains uncertain. Laboratory tests such as ISO 17556 are widely applied, but they leave ambiguities regarding reactor setup, soil preparation, and operational conditions, resulting in inconsistent interpretations and limited reproducibility. This study modified the ISO 17556 framework by establishing a decision framework and a validated standard soil protocol. Preliminary respirometry tests identified Arakida-soil as a suitable base medium and demonstrated that compost addition elevates background respiration, obscuring sample degradation signals. Therefore, compost-free standard soil (sand:clay:soil AK = 70:10:20) was selected. Reactor operation was standardized using a 500 mL vessel, an initial 3–5 day aeration interval followed by 10-day intervals. Continuous respirometry (2-h logging) was integrated with time-resolved material characterization (ATR-FTIR, DSC, SEC), enabling direct comparison of mineralization dynamics with structural changes.

Three BP films with different polymer compositions were evaluated for 196 days. Results satisfied ISO 17556 validity criteria and revealed distinct mechanisms: Sample A (PHB–PBAT) degraded rapidly via bulk erosion, Sample C (PLA–PBAT) showed delayed but comparable mineralization, while Sample B (PLA–PBAT, higher PLA fraction) exhibited limited degradation. The modified methodology provides clarified operational guidance and reproducible metrics (including kinetic rate constants), improving the comparability and mechanistic understanding of BP biodegradation in soil.

塑料至关重要，但也带来了环境挑战，特别是由于农业使用和处置不当而对土壤生态系统造成的挑战。生物降解塑料（bp）提供了一种潜在的解决方案，但它们在现实世界中的降解程度仍不确定。ISO 17556等实验室测试被广泛应用，但它们在反应器设置、土壤准备和操作条件方面留下了歧义，导致解释不一致和可重复性有限。本研究通过建立决策框架和经过验证的标准土壤协议修改了ISO 17556框架。初步的呼吸测试确定了荒田土是合适的基础培养基，并证明堆肥增加了本底呼吸，模糊了样品降解信号。因此，选择无堆肥标准土（砂：粘土：土AK = 70:10:20）。使用500ml容器标准化反应器操作，初始曝气间隔为3-5天，然后间隔10天。连续呼吸测量（2小时测井）与时间分辨材料表征（ATR-FTIR， DSC， SEC）相结合，可以直接比较矿化动态与结构变化。对三种不同聚合物组成的BP膜进行了196天的评价。结果符合ISO 17556的有效性标准，并揭示了不同的机制：样品A （PHB-PBAT）通过大块侵蚀快速降解，样品C （PLA - pbat）表现出延迟但相似的矿化，而样品B （PLA - pbat， PLA含量较高）表现出有限的降解。改进后的方法提供了明确的操作指导和可重复的指标（包括动力学速率常数），提高了土壤中BP生物降解的可比性和机理理解。

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引用次数: 0

Preparation and optimization of carbon fiber paper for fuel cell applications: Effect of dispersants, pulp and hot-pressing parameters 燃料电池用碳纤维纸的制备与优化：分散剂、纸浆和热压参数的影响

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-12-11 DOI: 10.1016/j.polymertesting.2025.109072

Jingwen Ouyang , Teng Zhang , Jun Xu , Xiongqi Peng

As a critical component in proton exchange membrane fuel cells (PEMFCs), carbon fiber paper (CFP) functions as the gas diffusion layer (GDL) backing, providing mechanical support, electrical conductivity, and effective gas–liquid transport. This work introduces a controllable wet papermaking fabrication route that integrates a dual dispersant regulation, refined pulp reinforcement and orthogonal optimization of hot-pressing parameters. The approach effectively addresses the long-standing issues of uneven fiber dispersion and suboptimal resin infiltration in conventional CFPs. The combination of polyethylene oxide (PEO) and anionic polyacrylamide (APAM) at a total concentration of 0.15 wt% (1:1 by mass) effectively stabilized the dispersion of 6 mm chopped carbon fibers (CFs), reducing large floc (>10 mm²) coverage to 3.0 % and improving sheet uniformity. Furthermore, incorporating 20 wt% softwood pulp (45 °SR) provided sufficient structural integrity for green sheets to withstand subsequent resin impregnation and hot-pressing processes. The result identified 15 wt% phenolic resin, 6 MPa compaction pressure, and 300 °C curing temperature as the optimal combination. The resulting CFP exhibited a uniformly impregnated and homogeneously compressed structure, showing an average pore size of 19.60 μm, 142 % higher tensile strength than the lowest-performing sample, conductivity of 31 mΩ cm, thermal diffusivity of 8.18 mm²/s and permeability of 1.56 Darcy.

作为质子交换膜燃料电池（pemfc）的关键部件，碳纤维纸（CFP）作为气体扩散层（GDL）的支撑层，提供机械支撑、导电性和有效的气液输送。本文介绍了一种集双分散剂调节、精浆补强和热压参数正交优化于一体的可控湿法造纸工艺路线。该方法有效地解决了传统CFPs中纤维分散不均匀和树脂浸润不理想的长期问题。聚乙烯氧化物（PEO）和阴离子聚丙烯酰胺（APAM）的总浓度为0.15 wt%（质量比为1:1）的组合有效地稳定了6mm短切碳纤维（CFs）的分散，将大絮团（>10 mm2）覆盖率降低到3.0%，并改善了薄片的均匀性。此外，加入20%软木纸浆（45°SR）为绿色板材提供了足够的结构完整性，以承受随后的树脂浸渍和热压工艺。结果表明，酚醛树脂用量为15wt %，压实压力为6mpa，固化温度为300℃为最佳组合。制备的CFP具有均匀浸渍和均匀压缩的结构，平均孔径为19.60 μm，抗拉强度比最差样品高142%，电导率为31 mΩ cm，热扩散率为8.18 mm2/s，渗透率为1.56 Darcy。

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引用次数: 0

2-Vinylanthraquinone-grafted XLPE suppresses AC electrical treeing by deep-trap regulation 2-乙烯蒽醌接枝交联聚乙烯通过深阱调控抑制交流电树生长

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-12-11 DOI: 10.1016/j.polymertesting.2025.109071

Ke Li , Lu-Ming Zhou , Yun-Xiao Zhang , Yuan-Xiang Zhou

Electrical treeing is a primary degradation pathway in cross-linked polyethylene (XLPE) cable insulation, making enhancement of the tree-initiation voltage (TIV) critical for reliable high-voltage operation. We report a peroxide-assisted grafting strategy that covalently incorporates 2-vinylanthraquinone (VAQ) into XLPE during standard crosslinking, thereby addressing the migration and durability limitations of physically blended stabilizers. The grafted VAQ introduces deep electronic traps and mitigates defect-driven degradation, increasing the characteristic TIV by more than 160 % and markedly suppressing tree growth under AC voltage. This migration-resistant, trap-engineered stabilization provides a practical route to improve long-term insulation reliability and is directly relevant to the design of ultra-high-voltage polymeric cables.

电气树形是交联聚乙烯（XLPE）电缆绝缘的主要降解途径，因此树形起始电压（TIV）的提高对于可靠的高压运行至关重要。我们报道了一种过氧化物辅助接枝策略，该策略在标准交联过程中将2-乙烯蒽醌（VAQ）共价结合到XLPE中，从而解决了物理混合稳定剂的迁移和耐久性限制。接枝的VAQ引入了深度电子陷阱，减轻了缺陷驱动的退化，将特征TIV提高了160%以上，并显著抑制了交流电压下的树生长。这种抗偏移、陷阱设计的稳定性为提高长期绝缘可靠性提供了切实可行的途径，并与超高压聚合物电缆的设计直接相关。

引用次数: 0

Gas-assisted technology enhanced micro-dimensional accuracy in 3D printing 气体辅助技术提高了3D打印的微观尺寸精度

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-12-11 DOI: 10.1016/j.polymertesting.2025.109073

Jianhua Xiao , Yinglan Liu , Feiyan Wang , Yanfeng Gao , Xiaojie Zhang , Jincheng Wang

Fused Filament Fabrication (FFF) is restricted from high-precision manufacturing applications due to the poor dimensional accuracy of the printed parts. Gas-assisted 3D printing, a novel additive manufacturing technology, addresses this limitation by injecting continuous high-pressure and high-temperature gas into the interface between the nozzle wall and molten filament, which creates a full-slip condition that modifies the polymer's shear rate field. This study investigates the mechanisms of layer accuracy enhancement in gas-assisted 3D printing through theoretical analysis and experimental validation. A geometric model including both the full-stick and full-slip zones within the nozzle was established to analyze the shear rate field, shear stress field, and deformation behavior of the molten filament. High-speed imaging and scanning electron microscopy (SEM) were utilized to characterize the dimensional deviations of extruded filaments and deposited layers. Experimental results confirm that gas-assisted 3D printing significantly improves the micro-dimensional accuracy of deposited layers. For nominal layer thicknesses of 100 μm and 300 μm, the fluctuation of deposited layer thickness was reduced to within ±5 μm and ±10 μm, respectively. Additionally, the surface quality of the Z-seam was notably enhanced. This study indicates that, in the gas-assisted 3D printing process, the melt undergoes elastic recovery under zero shear stress in the full-slip zone, which suppresses dimensional instability and improves the micro-dimensional accuracy of printed parts.

由于打印件的尺寸精度较差，电熔丝制造（FFF）在高精度制造中的应用受到限制。气体辅助3D打印是一种新型的增材制造技术，它通过向喷嘴壁和熔融长丝之间的界面注入连续的高压和高温气体来解决这一限制，从而创造了一个改变聚合物剪切速率场的全滑移条件。本研究通过理论分析和实验验证，探讨了气体辅助3D打印中层精度提高的机理。建立了包括喷嘴内全粘区和全滑区在内的几何模型，分析了熔丝的剪切速率场、剪切应力场和变形行为。利用高速成像和扫描电子显微镜（SEM）对挤压细丝和沉积层的尺寸偏差进行了表征。实验结果证实，气体辅助3D打印显著提高了沉积层的微观尺寸精度。当标称层厚为100 μm和300 μm时，沉积层厚度波动分别减小到±5 μm和±10 μm以内。此外，z缝的表面质量也得到了显著提高。研究表明，在气体辅助3D打印过程中，熔体在全滑移区零剪切应力下进行弹性恢复，抑制了尺寸不稳定性，提高了打印件的微观尺寸精度。

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引用次数: 0

Influence of injection volume rate–driven temperature evolution on the molecular and mechanical properties of PA6.6 in injection molding 注射体积速率驱动的温度变化对PA6.6分子力学性能的影响

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-12-09 DOI: 10.1016/j.polymertesting.2025.109075

David Zidar, Zahra Shahroodi, Roman Staudigl, Walter Friesenbichler, Thomas Lucyshyn, Clemens Holzer

This study investigates the influence of injection volume rate (IVR) on local temperature development in a narrow slit and its effects on the mechanical and molecular properties of unfilled polyamide 6.6 (PA 6.6). An in-situ measurement setup was developed to capture high-resolution temperature profiles across the melt flow path during injection molding. Increasing IVR resulted in a substantial rise in peak melt temperatures, exceeding 500 °C at high IVR in the center region of the slit. However, these extreme temperatures were sustained only for fractions of a second, and the 350 °C threshold was never maintained for more than 2.5 s under any condition. Based on these thermal profiles, significant thermo-oxidation degradation might be expected. Nevertheless, differential scanning calorimetry with oxidative induction time (DSC-OIT) and gel permeation chromatography (GPC) and Fourier Transform Infrared Spectroscopy (FTIR) revealed no measurable signs of chemical degradation. Mechanical properties showed only minor variations, most likely arising from physical effects such as molecular orientation and chain entanglement rather than chemical changes. These findings indicate that, within the investigated processing window, high IVR can induce extreme but short-lived thermal loads without compromising polymer integrity.

本文研究了注射体积速率（IVR）对窄缝内局部温度变化的影响及其对未填充聚酰胺6.6 （pa6.6）力学和分子特性的影响。开发了一种原位测量装置，用于捕获注塑过程中熔体流动路径的高分辨率温度曲线。增加IVR导致峰值熔体温度大幅上升，在狭缝中心区域的高IVR处超过500°C。然而，这些极端温度只持续了几分之一秒，在任何条件下，350°C的阈值从未保持超过2.5秒。基于这些热剖面，可以预期会发生显著的热氧化降解。然而，含氧化诱导时间的差示扫描量热法（DSC-OIT）、凝胶渗透色谱法（GPC）和傅里叶变换红外光谱法（FTIR）均未发现可测量的化学降解迹象。机械性能只有微小的变化，很可能是由于分子取向和链缠结等物理效应，而不是化学变化。这些发现表明，在研究的加工窗口内，高IVR可以诱导极端但短暂的热负荷，而不会影响聚合物的完整性。

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引用次数: 0

Enhancing hydrophobicity and corrosion resistance of epoxy resin coatings using KH570-ZrO2 nanoparticles 利用KH570-ZrO2纳米颗粒增强环氧树脂涂料的疏水性和耐腐蚀性

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-12-09 DOI: 10.1016/j.polymertesting.2025.109070

Youfan Wu , Qianqian Yang , Haibao Zhang , Yutong Zhou , Haoyan Guo , Zhenjun Wang , Gang Li

Epoxy resin has excellent adhesion, mechanical strength, environmental adaptability and corrosion resistance. As a concrete coating, it can effectively seal internal pores, prevent the penetration of water and corrosive ions. However, the epoxy resin has a relatively high content of hydrophilic groups and lacks an effective physical barrier structure. In this work, KH570-ZrO₂ nanoparticles were synthesized by modifying zirconium oxide (ZrO₂) with 3-Methacryloxypropyltrimethoxysilane (KH570) and then mixed with epoxy resin to prepare epoxy coatings. The thermal properties, mechanical properties, hydrophobicity and corrosion resistance of the coatings were studied respectively. The results indicated that when the content of ZrO₂ particles was 3.0 wt% of the epoxy resin, the modified epoxy coating demonstrated the most notable enhancements in both thermal and mechanical properties. Moreover, it exhibited optimal hydrophobicity and corrosion resistance. The KH570-ZrO₂ nanoparticles constructed a micro-nano composite rough structure. Meanwhile, low surface energy organosilane segments were introduced. These two factors jointly decreased the contact. In addition, KH570-ZrO₂ particles are uniformly dispersed in the cross linked network. Through the “maze effect”, they extend the diffusion paths of environmental moisture, oxygen, and various ions, thereby effectively inhibiting the penetration of these media into the concrete matrix. Overall, this work successfully improved the mechanical, hydrophobic and corrosion resistant properties, offering an effective technique for enhancing the durability of protective coatings.

环氧树脂具有优异的附着力、机械强度、环境适应性和耐腐蚀性。作为混凝土涂层，能有效密封内部孔隙，防止水和腐蚀离子的渗透。然而，环氧树脂的亲水性基团含量较高，缺乏有效的物理屏障结构。本文以3-甲基丙烯氧基丙基三甲氧基硅烷（KH570）对氧化锆（ZrO2）进行改性，合成了KH570-ZrO2纳米粒子，并与环氧树脂混合制备环氧涂料。研究了涂层的热性能、力学性能、疏水性和耐腐蚀性。结果表明，当ZrO2颗粒含量为环氧树脂的3.0 wt%时，改性后的环氧涂层的热性能和力学性能都得到了最显著的提高。此外，它还具有最佳的疏水性和耐腐蚀性。KH570-ZrO2纳米颗粒构建了微纳复合粗糙结构。同时介绍了低表面能有机硅烷段。这两个因素共同降低了接触。此外，KH570-ZrO2颗粒均匀分散在交联网络中。它们通过“迷宫效应”延长了环境水分、氧气和各种离子的扩散路径，从而有效地抑制了这些介质对混凝土基体的渗透。总的来说，这项工作成功地改善了机械、疏水和耐腐蚀性能，为提高保护涂层的耐久性提供了一种有效的技术。

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引用次数: 0

The relationship between strength and elasticity in silk hydrogels by inter-vs. intramolecular β-sheet formation 用inter-vs研究了蚕丝水凝胶强度与弹性的关系。分子内β片的形成

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-12-09 DOI: 10.1016/j.polymertesting.2025.109069

So Yeun Choi , Sunny Lee , Cheol Sang Kim , Chan Hee Park

Silk fibroin (SF) is most commonly used in tissue engineering and regenerative medicine due to its excellent biocompatibility and mechanical strength. In particular, SF hydrogels can mimic the three-dimensional extracellular matrix (ECM), offering a supportive environment for cellular activities. However, their mechanical properties are difficult to precisely control, which limits their application in load-bearing or function-specific tissue scaffolds. Mechanical performance in SF hydrogels is primarily governed by changes in secondary structure, especially β-sheet formation, which correlates with crystallinity and physical crosslinking. Most prior studies have focused on the total amount of β-sheet content, overlooking how its arrangement—intermolecular versus intramolecular—within the three-dimensional hydrogel network influences functional behavior. In this study, we systematically analyzed the relationship between β-sheet structural arrangement and physical properties by applying post-treatment with three different solvents—PBS buffer, methanol (MeOH), and dimethylformamide (DMF)—following UV-induced crosslinking of methacrylated SF (Sil-MA) hydrogels. PBS was used as a control mimicking physiological conditions, while MeOH and DMF were selected for their distinct β-sheet induction mechanisms. The results demonstrated that MeOH rapidly induces intermolecular β-sheet stacking and lamellar structure, enhancing stiffness, while DMF promotes intramolecular folding and β-turns, increasing elasticity. These molecular-level structural differences were directly linked to variations in swelling, degradation rate, and mechanical responses. Overall, the findings provide a scientific basis for controlling the functional performance of silk hydrogels by modulating post-treatment conditions, which will enable the precise design of custom bioscaffolds for regenerative applications requiring specific combinations of elasticity and strength.

丝素蛋白具有良好的生物相容性和机械强度，在组织工程和再生医学中应用最为广泛。特别是，SF水凝胶可以模拟三维细胞外基质（ECM），为细胞活动提供支持环境。然而，它们的机械性能难以精确控制，这限制了它们在承重或功能特异性组织支架中的应用。SF水凝胶的力学性能主要受二级结构的变化，特别是β-片的形成，这与结晶度和物理交联有关。大多数先前的研究都集中在β片含量的总量上，而忽略了其在三维水凝胶网络中的排列（分子间和分子内）如何影响功能行为。在这项研究中，我们系统地分析了β-片结构排列与物理性能之间的关系，采用三种不同的溶剂- pbs缓冲液，甲醇（MeOH）和二甲酰胺(DMF) -在紫外线诱导的甲基丙烯酸化SF （Sil-MA）水凝胶交联后进行后处理。PBS作为模拟生理条件的对照，而MeOH和DMF因其不同的β-sheet诱导机制而被选择。结果表明，MeOH快速诱导分子间β-片层堆叠和层状结构，增强了材料的刚度，而DMF促进分子内折叠和β-转动，增加了材料的弹性。这些分子水平上的结构差异与膨胀、降解率和机械反应的变化直接相关。总的来说，这些发现为通过调节后处理条件来控制丝水凝胶的功能性能提供了科学依据，这将使定制生物支架的精确设计能够用于需要特定弹性和强度组合的再生应用。

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引用次数: 0

Towards biaxial fatigue experiments of elastomers using square and cruciform geometries in planar tension conditions 平面拉伸条件下方形和十字形弹性体的双轴疲劳试验

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-11-29 DOI: 10.1016/j.polymertesting.2025.109060

Ali Esmaeili , Deepak George , Lewis Tunnicliffe , Ian Masters , Mokarram Hossain

Soft materials such as natural rubber, hydrogels, and biological tissues have anisotropic properties and are subject to cyclic biaxial loading during their service lives. This requires biaxial loading rather than uniaxial; however, no agreed standard protocol exists. Therefore, the aim of this study is to provide preliminary suggestions for reliable and consistent biaxial fatigue tests so that a good degree of biaxiality and efficiency can be thoroughly achieved. Several biaxial loading tests (equi-biaxial and unequal-biaxial) were conducted on natural rubber and ecoflex using different geometries including cruciform and square configurations. Three criteria were defined to evaluate the equi-biaxiality performance: (i) test function related to homogeneous strain distribution in the field of interest, (ii) degree of efficiency corresponding to the ratio of strain in the field of interest (gauge section located in the middle regions) to the maximum strain far from the middle area, and (iii) strain ratio, used for fatigue test. Results showed that cruciform geometry underperformed in equi-biaxiality criteria, i.e., samples possessed high uniaxial strain in the arm whereas the simple square geometry could reach a higher degree of biaxiality and efficiency. The highest equi-biaxiality performance was obtained for the optimized square geometry in such a way that a maximum equi-biaxial strain of 65 % was achieved in the field of interest while possessing a degree of efficiency of 0.66 and strain ratio of 1.96. A successful unequal-biaxial fatigue test of up to two million cycles was conducted on the optimized square specimen made of ecoflex. Finally, a new square configuration with circular cavity in the middle was suggested for future biaxial characterization and standardization of biaxial tests in which the numerical study yielded a degree of efficiency of 1 and strain ration of 2.12 manifesting a considerable improvement in the biaxiality performance.

软材料如天然橡胶、水凝胶和生物组织具有各向异性，在其使用寿命期间受到循环双轴载荷的影响。这需要双轴加载而不是单轴加载；然而，目前还没有达成一致的标准协议。因此，本研究的目的是为可靠和一致的双轴疲劳试验提供初步建议，从而彻底实现良好的双轴性和效率。对天然橡胶和ecoflex进行了几种双轴（等双轴和不等双轴）加载试验，采用不同的几何形状，包括十字形和方形配置。定义了三个评价等双轴性性能的标准：(i)与感兴趣区域内均匀应变分布相关的试验函数，（ii）感兴趣区域（位于中间区域的规范截面）应变与远离中间区域的最大应变之比对应的效率程度，以及（iii）用于疲劳试验的应变比。结果表明，十字形几何结构在等双轴性条件下表现不佳，即样品在臂部具有较高的单轴应变，而简单的方形几何结构可以达到更高的双轴性和效率。优化后的方形几何结构获得了最高的等双轴性能，在感兴趣的领域中获得了65%的最大等双轴应变，而效率度为0.66，应变比为1.96。对优化后的ecoflex方形试件进行了200万次的非等双轴疲劳试验。最后，提出了一种新的中间有圆腔的方形结构，用于未来的双轴特性和双轴试验的标准化，其中数值研究得出的效率度为1，应变比为2.12，表明双轴性能有了很大的改善。

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引用次数: 0

Multiaxial characterization of cross-ply and quasi-isotropic flax bio-composites using a modified Arcan fixture and digital image correlation 使用改进的Arcan夹具和数字图像相关技术对交叉铺层和准各向同性亚麻生物复合材料进行多轴表征

IF 6 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing

Pub Date : 2025-11-28 DOI: 10.1016/j.polymertesting.2025.109059

Zoran Bergant, Tomaž Kek, Andraž Maček, Miroslav Halilovič, Roman Šturm

This study investigates the mechanical behavior, stress–strain states and damage evolution of flax-fiber reinforced polymer composites under various loading angles using Arcan specimens with V-notches. Three stacking sequences, cross-ply [0/90]_4s, quasi-isotropic [45/−45/0/90]_2s, and angled cross-ply [45/−45]_4s, were examined to assess their response to combined tension and shear loading at angles of 0°, 45°, and 90°. Digital Image Correlation (DIC) was employed to capture detailed strain fields and principal strain orientations, enabling direct comparison with numerical predictions from finite element modelling. Results show that the [45/−45]_4s laminate exhibits superior shear load-bearing capacity due to the transformation of shear into tensile and compressive stresses within ±45° plies. Notch sensitivity varied significantly among laminates, with the [45/−45/0/90]_2s configuration showing greater damage tolerance, a smaller strength drop at off-axis angles, and a reduced notch effect compared to cross-ply laminates. The study reveals complex strain localization patterns and fiber-matrix interactions influencing crack initiation and propagation. These findings enhance the understanding of anisotropic damage mechanisms in natural fiber composites and provide valuable insights for optimizing biocomposite layups in structural applications subjected to multiaxial stress–strain states.

采用带v形缺口的Arcan试样，研究了不同加载角度下亚麻纤维增强聚合物复合材料的力学行为、应力-应变状态及损伤演化。研究了三种堆叠顺序，即交叉铺层[0/90]4s、准各向同性铺层[45/−45/0/90]2s和角度交叉铺层[45/−45]4s，以评估它们在0°、45°和90°角度下对联合张力和剪切载荷的响应。采用数字图像相关（DIC）捕获详细的应变场和主应变方向，从而可以与有限元模型的数值预测进行直接比较。结果表明：[45/−45]4s层合板在±45°层合层内剪切向拉、压应力的转变使其具有较好的剪切承载能力；缺口敏感性在层压板之间存在显著差异，与交叉层压板相比，[45/−45/0/90]2s结构具有更大的损伤容限，离轴角强度下降较小，缺口效应较小。研究揭示了复杂的应变局部化模式和纤维-基体相互作用对裂纹萌生和扩展的影响。这些发现增强了对天然纤维复合材料各向异性损伤机制的理解，并为在多轴应力-应变状态下结构应用中优化生物复合材料层提供了有价值的见解。

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