碳纤维表面处理对碳纤维/聚丙烯复合材料界面结合性能的影响

研究了电化学氧化、环氧上浆处理对碳纤维/聚丙烯(CF/PP)复合材料界面结合性能的影响,首先通过AFM、XPS等测试不同碳纤维的表面形貌和化学性质,然后借助微球脱粘实验考察对比不同CF/PP的界面剪切强度(IFSS)。结果显示高温碳化后的碳纤维表面呈惰性,复合材料IFSS仅有3.76 MPa;经过电化学氧化处理,表面粗糙度增大,羟基和羧基基团增多,IFSS增加到4.85 MPa;上浆处理后,表面引入活性的环氧基团,IFSS进一步增加到5.51 MPa,同时界面均匀性也有所改善。根据结果分析,碳纤维表面性质改变引起的界面区域机械锁合、范德华力以及分子链缠结作用增加是界面性能提升的主要原因。但与相容剂相比,传统碳纤维表面处理对CF/PP界面改善效果相对较弱,开发更加有效的改性方法十分必要。     

环氧树脂上浆剂对PAN基碳纤维性能的影响

分别以KD-213,YD-128环氧树脂、复合环氧树脂及油酸酰胺改性的复合环氧树脂(改性环氧树脂)为主体的上浆剂对聚丙烯腈基碳纤维(PANCF)进行上浆,对上浆纤维的加工性能、表面形貌及其界面剪切强度(IFSS)进行了研究。结果表明:上浆剂改善了PANCF的耐磨性、毛丝量、耐水性及其复合材料的IFSS。其中改性环氧树脂上浆剂为最佳,可在PANCF表面形成一层完整的柔韧性光滑薄膜,上浆后的PANCF的耐磨次数为1887,毛丝量为0.14mg,吸水率小于等于0.005%,复合材料IFSS较未上浆纤维提高38.5%,达87.26GPa。     

上浆剂粒径对碳纤维性能的影响

采用不同粒径的上浆剂，测试其粒径，并观察其稳定性；对不同种类的碳纤维进行上浆处理，测试SEM图像、展纱率、毛丝量、复丝拉伸强度、复合材料拉伸强度和层间剪切强度。结果表明：粒径在100 nm以下的上浆剂稳定性最优，放置一年内粒径没有明显变化；粒径在1 000 nm以下的上浆剂在碳纤维表面的分布较均匀；粒径在1 000 nm以下上浆剂的碳纤维的展纱率一般，毛丝量较低；使用粒径在1 000 nm以下上浆剂的碳纤维层间剪切强度较高；使用三种粒径上浆剂的碳纤维拉伸强度相差不明显，说明拉伸强度与上浆剂的关系较小；干喷湿纺碳纤维的层间剪切强度明显低于湿纺碳纤维。     

PAN基高模碳纤维阳极氧化的表面处理

采用阳极氧化法对PAN基高模碳纤维进行连续表面处理,重点研究了氧化电流密度对碳纤维宏观力学性能、表面形貌、表面酸性官能团以及碳纤维增强树脂基复合材料(CFRP)层间剪切强度(ILSS)的影响。结果表明,电流密度对纤维力学性能、表面形貌影响不大;氧化后纤维表面总的酸性官能团显著提高,最大增幅达13倍左右;适当的处理条件可使CFRP的ILSS从28.4 MPa提高到80 MPa以上。     

复配酰胺酸乳液改性玻璃纤维增强环氧树脂界面性能的研究

实验合成了酰胺酸乳液(SA-1),并添加聚乙烯吡咯烷酮进行复配(SA-2),通过纳米粒度分析仪、透射电子显微镜(TEM)和傅里叶红外光谱仪(FT-IR)测定乳液粒径及干燥成分的官能团结构。利用扫描电子显微镜(SEM)和原子力显微镜(AFM)研究处理前后玻璃纤维的表面形貌,并分别用单丝拉伸和微脱黏法测定单纤维的拉伸性能和复合材料的界面剪切性能(IFSS)。结果表明,SA-2乳液平均粒径为99 nm,分布范围为21 nm~220 nm,优于SA-1。SA-1乳液涂覆处理的膜层光滑,平均厚度为0.20μm,而SA-2处理后,玻璃纤维的表面粗糙度增大,膜层厚度为0.12μm。SA-1处理后玻璃纤维单丝拉伸性能从1.401 GPa降至1.369 GPa,GF/环氧树脂复合材料IFSS从20.06 MPa增至26.84 MPa;SA-2处理后单丝拉伸强度降至1.383GPa,复合材料IFSS为32.70 MPa,提升了63.01%。     

张力对PAN预氧化纤维结构和性能的影响

在预氧化过程中通过施加不同张力制备了四组PAN预氧化纤维,并利用单纤维强力测试仪、元素分析仪、X射线衍射仪、扫描电子显微镜等对PAN基碳纤维原丝及预氧化纤维的力学性能、微观结构和表面形貌进行了研究。结果表明,热处理过程中负载张力的增加会引起预氧化纤维表面形貌发生明显变化,预氧化纤维表面整体更加光滑,其(002)晶面的晶粒尺寸变大,微晶择优取向程度增加,预氧化纤维中C元素含量逐渐降低,O元素含量逐渐增加,预氧化纤维的拉伸强度、拉伸模量、断裂伸长率都呈现逐渐降低的趋势。     

羽毛球拍用碳纤维的表面改性与性能研究

为了对碳纤维进行表面接枝改性处理以增强碳纤维与环氧树脂间的结合力,提升碳纤维的综合力学性能并应用于羽毛球拍中。以亚临界水作为反应介质将三聚氰胺接枝到羽毛球拍用碳纤维表面,研究了反应时间对接枝改性碳纤维的表面形貌、接触角/表面能、单丝拉伸强度、界面剪切强度和冲击韧性的影响。结果表明,上浆处理后碳纤维表面不会有上浆剂残留,但是碳纤维纵向仍然可见加工沟槽,当三聚氰胺接枝改性时间延长至25min及以上时,碳纤维纵向沟槽有所变浅,且由于三聚氰胺在碳纤维上的聚集使得碳纤维表面粗糙度增大,局部可见块状聚集。经过三聚氰胺介质改性的碳纤维的接触角都小于接枝改性前、表面能都大于接枝改性前,随着接枝反应时间的延长,改性碳纤维的接触角不断减小。三聚氰胺接枝改性处理后碳纤维的单丝拉伸强度相较于接枝改性前有不同程度的降低,且随着反应时间的延长,单丝拉伸强度呈现先减小后增大的特征。随着三聚氰胺接枝改性时间的延长,CF-W-t的界面剪切强度、裂纹形成功、拓展功和冲击功呈现逐渐增加的趋势。将三聚氰胺接枝到羽毛球拍用碳纤维表面可以增强碳纤维的综合力学性能。     

阳极氧化对碳纤维及其复合材料性能影响的研究

对聚丙烯腈基碳纤维表面进行电化学氧化处理,用SEM扫描电镜、力学分析研究了阳极氧化对碳纤维表面形貌及力学性能的变化过程.结果表明：随着阳极氧化电流的增大,碳纤维表面沟槽缺陷逐渐消失,碳纤维力学性能先上升后下降,80 A氧化电流使碳纤维层间剪切强度提高变化15.3％、拉伸强度提高l2.1％;阳极氧化有利于提高碳纤维在热塑性材料中的粒径尺寸.     

耐高温PPBES溶液型碳纤维上浆剂的制备及性能

碳纤维增强高性能树脂基复合材料具有质轻、耐腐蚀性、力学强度高等特点,提升树脂与纤维界面强度可以优化复合材料综合性能。利用杂萘联苯聚芳醚树脂所具有的优异溶解性,选择氯仿∶N-甲基吡咯烷酮=2∶8混合溶液作为溶剂,制备耐高温溶液型上浆剂。通过对碳纤维进行上浆操作,在碳纤维表面包覆杂萘联苯聚芳醚砜树脂基团,纤维表面活性增加,当溶液上浆剂质量浓度为1.0%～1.5%时,树脂在碳纤维表面分散性较好,通过对比使用不同上浆剂的碳纤维增强树脂基复合材料的界面性能,使用浓度为1.5%的溶液上浆剂处理后的碳纤维相较于脱浆碳纤维,玻璃化转变温度从未处理的214℃提升至223℃,损耗因子从未处理的0.38下降到0.33,所制备的复合材料弯曲强度提升了12.0%,层间剪切强度提升了11.1%,证明溶液型上浆剂的使用提升了纤维与树脂间的界面性能。综上,溶液型上浆剂的使用能够提升碳纤维的表面活性,进而提升复合材料的弯曲强度、界面剪切强度,且提升效果优于市售常见环氧上浆剂,加工方便,有着广阔的市场应用前景。     

两种碳纤维上浆剂的比较

测试并比较了某国产上浆剂和进口上浆剂的黏度、表面张力、粒径等性能,研究了两种碳纤维上浆剂对聚丙烯腈基碳纤维表面形貌、耐磨性、水接触角、表面能、拉伸强度等性能的影响。结果表明,国产上浆剂固含量高、黏度高、粒径小,进口上浆剂黏度低、表面张力小、粒径分布窄。采用国产上浆剂上浆后的碳纤维,接触角为56.701°,毛丝量为0.15 mg/m,表面能为41.32 mJ/m²,耐磨次数为447次,拉伸强度为2.86 GPa;采用进口上浆剂上浆后的碳纤维表面光滑,接触角为51.063°,毛丝量为0.08 mg/m,表面能为47.26 mJ/m²,耐磨次数为461次,拉伸强度为2.95 GPa。     

Effects of surface treatment of carbon fiber: Tensile property,surface characteristics,and bonding to epoxy

In this article, effects of electrochemical oxidation and sizing treatment of PAN‐based carbon fibers (CFs) on the tensile properties, surface characteristics, and bonding to epoxy were investigated. As found, the electrochemical oxidation improves the tensile strength of single CF by 16.0%, due to weakening the surface stress concentration and smoothing the surface structure. Further sizing treatment shows a negligible effect on the tensile strength. Both oxidation and sizing treatments significantly improve the wettability and surface energies of CFs by introducing oxygen‐containing functional groups. Microbond test was conducted to characterize the interfacial shear strength (IFSS) between a single fiber and an epoxy droplet. The oxidation treatment increases IFSS slightly, which is due to the contradictory effects of the formation of chemical bonds between the resin and CFs, and the reduced mechanical interlocking. Further sizing treatment significantly enhances IFSS from 73.6 to 81.0 MPa, due to the formation of vast chemical bonds. Furthermore, the oxidation and sizing treatment can effectively reduce the degradation of IFSS to the hygrothermal ageing for the CF/epoxy system. POLYM. COMPOS., 37:2921–2932, 2016. © 2015 Society of Plastics Engineers     

Mechanical properties of carbon fiber composites modified with nano-SiO2 in the interphase

The performance of carbon fibers-reinforced composites is dependent to a great extent on the properties of fiber–matrix interface. To improve the interfacial properties in carbon fibers/epoxy composites, nano-SiO₂ particles were introduced to the surface of carbon fibers by sizing treatment. Atomic force microscope (AFM) results showed that nano-SiO₂ particles had been introduced on the surface of carbon fibers and increase the surface roughness of carbon fibers. X-ray photoelectron spectroscopy (XPS) showed that nano-SiO₂ particles increased the content of oxygen-containing groups on carbon fibers surface. Single fiber pull-out test (IFSS) and short-beam bending test (ILSS) results showed that the IFSS and ILSS of carbon fibers/epoxy composites could obtain 30.8 and 10.6% improvement compared with the composites without nano-SiO₂, respectively, when the nano-SiO₂ content was 1 wt % in sizing agents. Impact test of carbon fibers/epoxy composites treated by nano-SiO₂ containing sizing showed higher absorption energy than that of carbon fibers/epoxy composites treated by sizing agent without nano-SiO₂. Scanning electron microscopy (SEM) of impact fracture surface showed that the interfacial adhesion between fibers and matrix was improved after nano-SiO₂-modified sizing treatment. Dynamic mechanical thermal analysis (DMTA) showed that the introduction of nano-SiO₂ to carbon fibers surface effectively improved the storage modulus of carbon fibers/epoxy.     

Effect of Halloysite Nanotube Incorporation in Epoxy Resin and Carbon Fiber Ethylene/Ammonia Plasma Treatment on Their Interfacial Property

Abstract

Effects of halloysite nanotube (HNT) loading of up to 2% in epoxy resin on its mechanical properties were characterized. The interfacial property of the resin with carbon fiber nanocomposite was also studied. Single fiber composite (SFC) technique was used to characterize the carbon fiber/epoxy resin interfacial shear stress. Carbon fibers were also coated with ammonia/ethylene plasma polymer to obtain a thin coating of the polymer with amine groups that could react with the epoxy and thus improve the interfacial property. The results indicated that the Young’s modulus of HNT containing nanocomposites increased slightly up to a loading of 0.25% after which it started to decrease. The tensile strength, however, steadily decreased with increasing of HNT loading although the fracture strain did not change significantly. This might be related to the nanotube shape, size and clustering. The interfacial shear strength (IFSS) was also increased slightly with HNT loading. The ethylene/ammonia plasma polymer coated fibers exhibited significantly higher IFSS by over 150%, independent of the HNT loading. The highest IFSS obtained was almost 79 MPa for plasma treated fibers. The results suggest that the carbon fiber/epoxy interface is not affected by the incorporation of up to 1.5% of HNT. Furthermore, the fiber surface modification through plasma polymerization is an effective method to improve and control the IFSS.     

Interface improvement of carbon fiber/methylphenylsilicone resin composites by fiber surface coating of polyhedral oligomeric silsesquioxanes

To enhance interfacial properties of carbon fibers (CFs)-reinforced methylphenylsilicone resin (MPSR) composites, we introduced an appropriate interface reinforced by trisilanolphenyl-polyhedral oligomeric silsesquioxanes (trisilanolphenyl-POSS) between CFs and MPSR with a liquid phase deposition strategy. Chemical bonds among silanol groups of trisilanolphenyl-POSS, hydroxyl-functionalized CF (CF–OH), and silanol end groups of MPSR in the coating were expected to be formed through condensation reaction during the prepared process. CFs with and without sizing treatment-reinforced MPSR composites were prepared by a compression molding method. X-ray photoelectron spectroscopy revealed that trisilanolphenyl-POSS particles enhanced the contents of fiber surface oxygen-containing groups and silicon-containing functional groups. Scanning electron microscopy and atomic force microscopy images showed that trisilanolphenyl-POSS nanoparticles have been introduced onto the fiber surface obviously and the surface roughness increased sharply. Dynamic contact angle analysis indicated that trisilanolphenyl-POSS-modified sizing agent could improve the fiber wettability and surface energy significantly. Short-beam bending test and impact toughness test results showed that the interlaminar shear strength and impact resistance of the sized CFs composites were enhanced greatly with increasing amplitudes of more than 35 and 27% in comparison with those of untreated CF composites, respectively. Cryo-fractured surface topographies of composites confirmed that interfacial adhesion between CFs and MPSR has been improved after sizing treatment. Meanwhile, the sizing treatment does not decrease single fiber tensile strength.     

淀粉纳米晶对玻璃纤维的表面改性研究

采用自制的淀粉纳米晶(SNC)对玻璃纤维进行表面处理,增加其与环氧树脂基体的界面剪切强度(IFSS)。研究了处理方式、处理时间、SNC乙醇分散液浓度、热处理温度等工艺参数对SNC在玻璃纤维表面沉积情况的影响,以及对改性玻璃纤维与环氧树脂的界面性能的影响规律。采用扫描电子显微镜、单纤维强力仪对处理前后玻璃纤维进行表征,并采用微脱粘法测试玻璃纤维与环氧树脂的界面粘结情况。结果表明,当重力静置处理时间24 h,SNC乙醇分散液浓度为1 g/100 m L时,SNC在玻璃纤维表面均匀沉积,且能显著提高玻璃纤维与环氧树脂的IFSS,为27.29 MPa,较未处理的纤维增加29.3%。150℃热处理4 h后,X射线光电子能谱结果显示SNC与玻璃纤维形成化学键合,进一步增加纤维与环氧树脂的界面粘结,IFSS值达到32.30 MPa,较未处理的纤维增加53%,且纤维的拉伸强度得到较好的维持。     

Surface modification of ultra-high strength polyethylene fibers for enhanced adhesion to epoxy resins using intense pulsed high-power ion beam

The effects of intense pulsed high power ion beam (HPIB) treatment of ultra-high strength polyethylene (UHSPE) fibers on the fiber/epoxy resin interface strength were studied. For this study, argon ions were used to treat Spectra? 1000 (UHSPE) fibers in vacuum. Chemical and topographical changes of the fiber surfaces were characterized using Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), dynamic wettability measurements, and scanning electron microscopy (SEM). The fiber/epoxy resin interfacial shear strength (IFSS) was evaluated by the single fiber pull-out test. The FTIR-ATR and XPS data indicate that oxygen was incorporated onto the fiber surface as a result of the HPIB treatment. The wettability data indicate that the fibers became more polar after HPIB treatment and also more wettable. Although the total surface energy increased only slightly after treatment, the dispersive component decreased significantly while the acid-base component increased by a similar amount. SEM photomicrographs revealed that the surface roughness of the fibers increased following the HPIB treatment. The single fiber pull-out test results indicate that HPIB treatment significantly improved the IFSS of UHSPE fibers with epoxy resin. This enhancement in IFSS is attributed to increased roughness of the fiber surface resulting in mechanical bonding and in increased interface area, increased polar nature and wettability, and an improvement in the acid-base component of the surface energy after the HPIB treatment.     

Effects of electrophoretically deposited carbon nanofibers on the interface of single carbon fibers embedded in epoxy matrix

Electrophoretic deposition (EPD) was used to deposit carboxylic acid-functionalized carbon nanofibers (O-CNFs) on the surface of single carbon fibers. Using the single fiber fragmentation technique and Weibull analysis, interfacial shear strength (IFSS) was estimated for different fiber surface treatments. Samples for sized, unsized, O-CNF deposited sized, and O-CNF deposited unsized carbon fibers were tested. Additionally, the effects of EPD were investigated by testing sized and unsized carbon fiber samples exposed to an electric field in water. Removal of the fiber sizing decreased IFSS by approximately 27%, but addition of O-CNFs to the unsized fiber surface led to an increase of 15% compared to the sized base fiber. The O-CNF deposited sized fibers provided IFSS increases of 207.6% and 66.9% for 1 and 5 min deposition durations, respectively. The surface morphology of all samples was characterized, and those containing homogeneous deposition of closely bound O-CNFs provided the highest IFSS values. Exposing sized fibers to the electric field for 1 min led to an IFSS increase of 79%, while unsized fibers undergoing the same treatment provided increases of 7.7% and 46% compared to the base sized fiber and unsized fiber samples, respectively.     

阳极氧化处理对碳纤维强度离散性的影响及表征

采用阳极氧化法对碳纤维进行了表面处理,并探讨了表面处理后碳纤维接触角、强度的变化和碳纤维强度离散性的表征方法。研究发现:碳纤维在阳极氧化表面处理后,接触角变小,说明浸润性增强,强度略有下降,离散性略有增大;表面处理后随放置时间延长,接触角有一定程度增大,强度继续下降,离散性继续增大。用强度CV值和韦伯分布拟合强度所得的韦伯模数两种不同指标表征了表面处理后碳纤维的强度离散性,经验证,两种表征方法的一致性好。