Temperature-dependent toughening of carbon/epoxy composites using rubbery NBR/PCL nanofibers: Mode I fracture and damage mechanisms

IF 8.1 2区材料科学 Q1 ENGINEERING, MANUFACTURING

Composites Part A: Applied Science and Manufacturing Pub Date : 2025-09-25 DOI:10.1016/j.compositesa.2025.109321

Hesamaldin Saghafi , Isa Ahmadi , Ramin Khamedi , Hamed Saghafi , Tommaso Maria Brugo , Emanuele Maccaferri , Francesco Mongioì , Andrea Zucchelli

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Abstract

This study evaluates the temperature-dependent toughening effect of rubbery NBR/PCL nanofibers in carbon/epoxy composites under mode I loading. Double Cantilever Beam (DCB) tests at six temperatures (−30 °C to 120 °C) measured interlaminar fracture toughness in non-modified and nano-modified laminates. At 30 °C, modified specimens achieved 164 % higher initiation toughness and 394 % higher propagation toughness than non-modified ones, driven by nano-modified interactions that enhanced energy dissipation through plastic deformation and fiber bridging. However, at elevated temperatures (90 °C and 120 °C), toughness declined sharply due to modified matrix softening above the rubber’s glass transition temperature (T_g) and PCL melting point, impairing crack-bridging efficacy. Fractographic analysis revealed contrasting failure modes: non-modified specimens exhibited matrix cracking (cusps) and fiber–matrix debonding, with cusp height reduction at higher temperatures. Nano-modified specimens showed hole-rich fracture surfaces and robust fiber–matrix adhesion at lower temperatures, confirming nanofiber-mediated toughening. This effect diminished at higher temperatures as nanofibers softened, reducing energy absorption. The results underscore the temperature sensitivity of NBR/PCL nanofibers in enhancing fracture resistance, with peak performance at lower temperatures. These findings provide critical insights for optimizing composite designs for applications exposed to varying thermal conditions, balancing toughening benefits against temperature-induced limitations.

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丁腈橡胶/PCL纳米纤维对碳/环氧复合材料的温度依赖增韧：I型断裂和损伤机制

本研究评估了橡胶NBR/PCL纳米纤维在碳/环氧复合材料中在I型载荷下的温度依赖性增韧效果。双悬臂梁（DCB）测试在六种温度下（- 30°C至120°C）测量未改性和纳米改性层压板的层间断裂韧性。在30°C时，由于纳米修饰的相互作用增强了塑性变形和纤维桥接的能量耗散，改性试样的起始韧性比未改性试样高164%，扩展韧性比未改性试样高394%。然而，在高温下（90°C和120°C），由于改性基体软化高于橡胶的玻璃化转变温度（Tg）和PCL熔点，韧性急剧下降，削弱了裂缝弥合效果。断口分析揭示了不同的破坏模式：未改性的试样表现为基体开裂（尖头）和纤维基体脱粘，尖头高度在高温下降低。纳米改性的样品在低温下显示出富含孔洞的断口表面和强大的纤维基质粘附，证实了纳米纤维介导的增韧。这种效应在高温下减弱，因为纳米纤维软化了，减少了能量吸收。结果表明，NBR/PCL纳米纤维在增强抗断裂性能方面具有温度敏感性，在较低温度下性能达到峰值。这些发现为优化不同热条件下的复合材料设计、平衡增韧效益和温度限制提供了重要见解。

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来源期刊

Composites Part A: Applied Science and Manufacturing 工程技术-材料科学：复合

CiteScore

15.20

自引率

5.70%

发文量

492

审稿时长

30 days

期刊介绍： Composites Part A: Applied Science and Manufacturing is a comprehensive journal that publishes original research papers, review articles, case studies, short communications, and letters covering various aspects of composite materials science and technology. This includes fibrous and particulate reinforcements in polymeric, metallic, and ceramic matrices, as well as 'natural' composites like wood and biological materials. The journal addresses topics such as properties, design, and manufacture of reinforcing fibers and particles, novel architectures and concepts, multifunctional composites, advancements in fabrication and processing, manufacturing science, process modeling, experimental mechanics, microstructural characterization, interfaces, prediction and measurement of mechanical, physical, and chemical behavior, and performance in service. Additionally, articles on economic and commercial aspects, design, and case studies are welcomed. All submissions undergo rigorous peer review to ensure they contribute significantly and innovatively, maintaining high standards for content and presentation. The editorial team aims to expedite the review process for prompt publication.