Enhancement mechanism of nylon 6 filler on the mechanical and frictional wear properties of carbon fiber-epoxy resin composites
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摘要: 碳纤维-环氧树脂复合材料具有高强高模、耐腐蚀、抗疲劳等优异性能,作为结构材料被广泛用于土木工程中。尼龙6具有良好的断裂韧性、自润滑性、减摩耐磨性等优点,将其作为填料加入至短切碳纤维-环氧树脂复合材料中有望大幅提升材料的力学和摩擦磨损性能。本文采用尼龙6改性短切碳纤维-环氧树脂复合材料,基于树脂基体优选方法制备了一种力学性能优异、耐高温且具有低摩擦系数和低磨损速率的高性能复合材料。试验研究了添加尼龙6对复合材料的热、力学及摩擦磨损性能的影响,结合微观形貌与结构分析,揭示了尼龙6对复合材料性能提升机制。研究发现,添加7.5wt%尼龙6后,复合材料的拉伸断裂韧性提升了199%,断裂破坏模式由脆性断裂转变为韧性断裂,拉伸断口形貌由“平原状”转变为“沟壑状”,玻璃化转变温度提升了15.2℃。添加10wt%尼龙6可以显著降低复合材料的摩擦系数(~80%)、磨损速率(~53%)、划痕宽度(~22%)、线粗糙度(~15%),耐磨损性能提升机制归因于尼龙6可在摩擦表面协助形成一层均匀致密的润滑隔离膜,使磨损类型由严重的疲劳磨损变为轻微的粘着磨损或磨粒磨损。Abstract: Carbon fiber-epoxy resin composites have excellent properties such as high strength and high modulus, corrosion and fatigue resistances, and are widely used as structural materials in civil engineering. Nylon 6 has advantages of great fracture toughness, self-lubrication, friction and wear reduction, etc. Its incorporation as a filler in short-cut carbon fiber-epoxy composites is expected to significantly improve mechanical and frictional wear properties. In this paper, a high performance composite with excellent mechanical properties, high temperature resistance, low coefficient of friction and wear rate was prepared through using short-cut carbon fiber-epoxy resin composites modified with nylon 6 based on the resin selection method. The effect of the addition of nylon 6 on the thermal, mechanical and frictional wear properties of composite was investigated, and the mechanism of nylon 6 on its performance enhancement was revealed by combining microscopic morphology and structural analysis. It was found that the tensile fracture toughness of the modified composites increased by 199% with the addition of 7.5wt% nylon 6, and the fracture damage mode changed from brittle fracture to ductile fracture, the tensile fracture morphology changed from "plain" to "gully" and the glass transition temperature increased by 15.2℃. The addition of 10wt% nylon 6 significantly reduced the frictional coefficient (~80%), wear rate (~53%), scratch width (~22%) and line roughness (~15%) of the composites. The improvement mechanism can be attributed to the fact that nylon 6 assisted in the formation of a uniform and dense lubricant isolation film on the scratch surface, which changed the wear type of the composites from the severe fatigue wear to the slight adhesive wear or abrasive wear.
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Key words:
- composites /
- epoxy resin /
- carbon fiber /
- nylon 6 /
- mechanical properties /
- friction and wear properties /
- wear mechanism
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表 1 耐高温复合材料用环氧树脂体系(HTREP)
Table 1. Epoxy resin systems for high temperature-resistant composites (HTREP)
Formula Ts-A AG80 F51 Hardener
(Ts-B∶HTDA)Normal EP 0 100% 0% 0% 3∶2 HTREP 1 0% 100% 0% 3∶2 2 0% 0% 100% 3∶2 3 67% 33% 0% 3∶2 4 67% 0% 33% 3∶2 5 50% 50% 0% 3∶2 6 50% 0% 50% 3∶2 Notes: HTDA—Methylcyclohexanediamine; Amine equivalents of the curing agents Ts-B and HTDA are 69 g/mol and 32 g/mol respectively; the epoxy equivalents of the epoxy resins Ts-A/F51 and AG80 are 196 g/mol and 111 g/mol respectively. 表 2 基于最优耐高温树脂基体的PA6/SCFs添加配方
Table 2. Formulation of PA6/SCFs additives based on optimal high temperature-resistant resin matrix
Specimens SCFs
/wt%PA6
/wt%BYK-066 N
/wt%Diluent
/wt%Control 10.0 0.0 1.0 2.0 EPCP2.5 10.0 2.5 1.0 2.0 EPCP5 10.0 5.0 1.0 2.0 EPCP7.5 10.0 7.5 1.0 2.0 EPCP10 10.0 10.0 1.0 2.0 Notes: EP—Optimal high-temperature resistant epoxy resin matrix; C—Short-cut carbon fibres (SCFs); P—Nylon 6 (PA6); Numbers—Mass ratio of PA6 additives. 表 3 耐高温环氧树脂基体力学/热力学性能
Table 3. Mechanical/thermomechanical properties of high temperature resistant epoxy resin substrates
Formula Bending strength/MPa Bending modulus/GPa Elongation/% Tg/℃ 0 115.3(±3.79) 3.26(±0.22) 4.34(±0.12) 90.4(±1.25) 1 62.3(±4.25) 3.24(±0.42) 1.32(±0.23) 201.2(±1.42) 2 81.6(±3.78) 2.58(±0.31) 1.98(±0.42) 169.7(±0.85) 3 79.5(±3.85) 3.68(±0.15) 2.34(±0.25) 157.7(±1.53) 4 91.5(±2.75) 3.41(±0.12) 2.96(±0.32) 141.3(±1.42) 5 132.1(±2.62) 4.69(±0.24) 3.45(±0.17) 173.6(±0.75) 6 107.5(±2.14) 4.01(±0.25) 3.68(±0.18) 151.6(±0.99) Note: Tg—Glass transition temperature. -
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