石墨烯/氧代氮代苯并環己烷/環氧樹脂/碳纖維積層板複合材料機械性質與疲勞特性之研究

Investigation on Mechanical Properties and Fatigue Behavior of Graphene/Benzoxazine/Epoxy/Carbon Fiber Reinforced Polymer Laminates Composites

李育誠(Yu-Cheng Li)

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(2014年)

摘要

本研究旨於利用氧代氮代苯并環已烷(Benzoxazine)與環氧樹脂(Epoxy)摻混作為高分子基材主體，透過氧代氮代苯并環已烷與環氧樹脂改質共聚與氧代氮代苯并環已烷其自組成網狀結構特性，提升基材機械性質與耐候性。採用石墨烯(Graphene)作為奈米補強材，強化纖維-基材介面相、提高層間機械強度與疲勞壽命。實驗過程中探討下列因素對材料性質之影響：(1) 不同含氧量類型之石墨烯、(2) 氧代氮代苯并環已烷對環氧樹脂之添加量、(3) 高含氧量石墨烯濃度對氧代氮代苯并環已烷/環氧樹脂/碳纖維積層板複合材料添加量之機械性質、(4)環境溫濕老化效應。
研究成果指出高含氧型石墨烯(RF-G)較低含氧型石墨烯(DF-G)有較佳的機械性質補強效果與分散性。高含氧型石墨烯於0.5wt%濃度其強度提升最高，相較環氧樹脂拉伸強度提高19.16%；彎曲強度提高13.13%。
高分子基材的試驗數據顯示添加30wt%氧代氮代苯并環已烷可顯著提高環氧樹脂基材之機械強度：拉伸強度提升43.67%；彎曲強度提升44%。但氧代氮代苯并環己烷/環氧樹脂共聚物為硬脆型材料，導致衝擊強度下降約70%。熱性質方面，玻璃轉化溫度為106.72℃，提升13.36%；熱膨脹係數約降低了13%；最大熱裂解溫度降低17.84℃；熱裂解速率則減緩了37.39%。
高含氧量型石墨烯於層間剪切強度與層間破裂韌性試驗下有顯著之提升效果，層間剪切強度提高22.82%；破裂韌性初始值提升112.93%；破裂韌性成長值提升135.21%。根據拉伸-拉伸動態疲勞試驗，添加石墨烯對於高應力等級群(92%-88%)之疲勞壽命均有2倍以上的顯著提升。高含氧量石墨烯因富含化學官能基團能強化微纖維與樹脂介面，提高抗脫層能力。
環境溫濕老化效應實驗數據說明添加30wt%氧代氮代苯并環已烷大幅降低材料吸濕性，吸濕速率降低51.84%。其中，高溫高濕(85℃/85%RH)對積層板複合材料之影響最為顯著，對高溫常濕(85℃/65%RH)環境有較佳的耐候性。濕度為主要影響因素，高溫則是加劇材料損傷程度。
本研究利用氧代氮代苯并環已烷改善基材特性並利用石墨烯增強層間機械性質，對於碳纖維積層板複合材料之機械性質與耐候特性均有顯著改善，以期運用於尖端複合材料之應用面。

關鍵字

石墨烯 ； 氧代氮代苯并環己烷 ； 環氧樹脂 ； 碳纖維 ； 機械性質 ； 疲勞行為 ； 環境效應 ； 複合材料

並列摘要

This research aims to define the characteristics of the mixture of benzoxazine/epoxy copolymer matrix and a reinforced nano-material –graphene. By polymerizing with epoxy and due to its self-construction structure, benzoxazine outstandingly upgrades the matrix mechanical properties and weathering resistance. Meanwhile, graphene notably intensifies the fiber-matrix interface, improving both interlaminar mechanical strength and dynamic fatigue life. The investigation includes: (1) Different oxygen-level functional group graphene concentration, (2) Benzoxazine filler content in epoxy matrix, (3) Oxygen-rich functional group graphene concentration in benzoxazine/epoxy/carbon fiber reinforced polymer (CFRP) mechanical properties, and (4) Hygrothermal aging effects.
The research results indicate that oxygen-rich functional group graphene (RF-G) shows better material properties and dispersion than oxygen-depleted functional group graphene (DF-G). Compared to epoxy, 0.5wt% RF-G/EP nanocomposites demonstrates 19.16% and 13.13% enhancement in tensile strength and flexural strength, respectively.
The matrix experimental results specify that the value of mechanical strength is proportional to benzoxazine filler content. In this study, 30wt% benzoxazine/epoxy significantly reinforces the mechanical strength: 43.67% increase in tensile strength; 44% in flexural strength. However, benzoxazine/epoxy becomes more brittle with the addition of benzoxazine. Therefore, the impact resistance strength reduces about 70%. In thermal properties, the glass transition temperature (Tg) elevates to 106.72℃(13.36% increase). Additionally, the maximum thermal decomposition temperature (Tdmax) enhances from 334.86℃ to 352.7℃ and the thermal decomposition rate decelerates by 37.39%.
The results support that graphene actually intensifies the interface properties, especially for interlaminar shear strength (22.82% increment) and fracture toughness (GIC(ini) increases 112.93%, GIC(prop) 135.21%). The tension-tension dynamic fatigue test confirms that fatigue life is remarkably improved more than twice with the addition of graphene.
In hygrothermal aging environment condition test result, 30wt% benzoxazine/epoxy substantially slows down by 51.84% of the water absorption rate. Moreover, the 85℃/85%RH condition causes the worst impact to CFRP composites compared with 25℃/65%RH, 25℃/85%RH, and 85℃/65%RH conditions. The humidity level is the critical dominant factor and high temperature further accelerates the material damage situation.

並列關鍵字

Graphene ； Benzoxazine ； Epoxy ； Carbon fiber ； Mechanical properties ； Fatigue ； Hygrothermal aging effects ； Composites

參考文獻

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