石墨烯補強共聚物高分子不連續碳纖維複合材料之機械性質與破壞行為研究

Investigation on Mechanical Properties and Fracture Behavior by Nanoscale Graphene Discontinuous Carbon Fiber Reinforced Copolymer (Epoxy/Benzoxazine) Composite

江家豪(Jia-Hao Juang)

指導教授 ： 葉銘泉

國立清華大學/工學院/動力機械工程學系/碩士(2015年)

https://doi.org/10.6843/NTHU.2015.00035

摘要

本研究主要主旨著重在氧代氮代苯并環已烷(Benzoxaine)與改質環氧樹脂混摻作為高分子基材主體。之後於高分子基材中添加石墨烯(Graphene)與短碳纖維(Short carbon fiber)之補強材，目的主要是為了探討其奈米尺度跟微米尺度補強材之補強效果，並強化多尺度混摻後之介面特性、以提高機械與疲勞性質。實驗中主要探討下量因素對材料之影響: (1)Benzoxaine對環氧樹脂的添加量、(2)奈米等級石墨烯與微米等級短碳纖維織之添加量、(3)多尺度混摻之複合材料的添加量
高分子複材研究指出添加20wt%Benzoxaine可顯著提高環氧樹脂基材之機械強度:拉伸強度提升21.37%、彎曲強度提升33.45%、彎曲模數提升13.86%，吸濕阻水率提升38.03%，但Benzoxaine屬於硬脆型材料，導致衝擊性質下降了55%。
當20wt%Benzoxaine/環氧樹脂複合材料添加奈米等級石墨烯則指出，0.5wt%GNPs添加量拉伸強度提升14.18%、吸濕阻水率提升22.83%;0.25wt%GNPs添加量彎曲強度提升了2.46%、彎曲模數上升8.05%。另外一方面，添加了微米等級短碳纖維則指出8wt%添加量有最好的機械性質:彎曲強度上升了22.93%，吸濕阻水率上升了9.84%.。
最後研究顯示GNPs-0.5wt%/SF-8wt%/Benzoxazine/環氧樹脂複合材料有最好的提升:拉伸提升22.62%、彎曲強度提升12.2%、衝擊強度提升39.07%、扭轉疲勞壽命提升了3.2到3.8倍，但因短碳纖維在加載過程會在纖維末端產生大量微裂紋，從而降低其延展性，彎曲模數反而下降33.84%。

關鍵字

石墨烯 ； Benzoxazine ； 改質環氧樹脂 ； 短碳纖維 ； 多尺度混摻 ； 機械性質 ； 疲勞性質 ； 不連續纖維複合材料

並列摘要

This study is focuses on the characteristics of the benzoxazine/epoxy copolymer matrix, combined thegraphene and micro-scale short carbon fibers to be reinforcement. In order to investigate the reinforced mechanism of the nano-scale and micro-scale additive, the interfacial properties, mechanical behavior, and fatigue failure would be realized on the mulit-scale reinforced composite. The researches includes: (1) Different contents of benzoxazine resin in Epoxy resin, (2) graphene and Micro-scale short carbon fibers concentration, (3) the interaction of multi-scale reinforcement material concentration
This research aims to discuss the effect of the mixture of nano-scale graphene and micro-scale short carbon fiber, notably intensifies the the mixture of multi-scale interface, improving and increasing both mechanical properties and dynamic fatigue life. The investigation includes:(1)Different Benzoxazine resin concentration in Epoxy,(2)Nano-scale graphene and Micro-scale short carbon fibers concentration.(3)Multi-scale reinforcement material concentration.
In the matrix experiment, the results indicate that the value of mechanical strength increases with the content of benzoxazine increased. From the results, the 20wt% benzoxazine/epoxy significantly improves the mechanical strength up to 21.37% improvement in tensile strength; 33.45% improvement in flexural strength; 13.86% improvement in flexural modulus; 38.03% improvement in resistance of water absorption.
However, because of the property benzoxazine is more brittle than epoxy, the impact strength of benzoxazine/epoxy copolymer reduces about 55%.
The research shows that addition of graphene in the optimum content of 20wt% benzoxazine/epoxy composite 14.18% improvement in tensile strength, 22.83% improvement in the resistance of water absorption by adding the 0.5wt% graphene; 2.46% improvement in flexural strength, and 8.05% improvement in flexural modulus by adding the 0.25wt% graphene.
It is showed that adding 8wt% micro-scale short carbon fiber has the best enhancement to the mechanical properties: increasing 22.93% in flexural strength and 9.84% in the resistance of water absorption.
Finally, the optimum content of GNPs-0.5wt%/SF-8wt%/ Benzoxazine/ Epoxy composites preform the best enhancement to the properties about 22.62% improvement in tensile strength, 12.2% improvement in flexural strength, and 39.07% improvement in impact strength, 3.2-3.8 times improvement in torsion fatigue life. Because of the reason of short carbon fiber will produce a lot of micro-cracks in the fiber-end, the stress concentration would influence the ductility and lead to cracks propagation. In the result, the flexural tests reveal about 33.84% downtrend in flexural modulus.

並列關鍵字

Graphene ； Benzoxazine ； Modified epoxy ； Short carbon fiber ； Multi-scale mixture ； Mechanical properties ； Fatigue behaviour ； Discontinuous fiber reinforced composite

參考文獻

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