接枝改性对F—12纤维及其环氧复合材料力学性能影响的研究

采用稀氢氧化钾溶液对Ｆ－１２纤维表面进行处理,将－ＣＯＯＫ基团引入到Ｆ－１２纤维表面,作为环氧氯丙烷接枝的引发剂,并分析了温度和时间对Ｆ－１２纤维拉伸到强度及其环氧复合材料层间剪切强度的影响。     

接枝偶联剂对F-12纤维表面改性的影响

用一种大分子接枝偶联剂ＭＧＣ对Ｆ－１２进行等离子体接枝改性,研究了ＭＧＣ的分子量和浓度对改性后的Ｆ－１２／环氧复合材料层间剪切强度的影响,还通过ＥＳＣＡ对改性机理进行了分析,实验结果表明：一定分子量的ＭＧＣ能够明显提高Ｆ－１２／环氧复合材料层间切强度。     

碳纤维γ射线辐照处理对其复合材料界面性能的影响

采用γ射线辐照方法对碳纤维（ＣＦ）进行改性,研究了辐照对ＣＦ增强复合材料层间剪切强度（ＩＬＳＳ）、ＣＦ复丝拉伸强度的影响,并使用Ｘ射线光电子能谱（ＸＰＳ）、扭辫分析、微脱粘测试等分析方法,对ＣＦ的表面化学组成和复合材料界面粘合强度进行了表征。结果表明,辐照使ＣＦ表面与环氧涂层发生了化学反应,复合材料界面粘合强度提高,ＩＬＳＳ增大,ＣＦ本体拉伸强度未发生变化。     

紫外线辐照对聚丙烯化学组成及复合材料界面的影响

研究了经紫外线照的聚丙烯的化学组成,表征了以辐照ＰＰ作为界面相容剂的玻纤／ＰＰ复合材料的界面结合强度和界面粘结状态。结果表明,紫外线辐照可在ＰＰ分子链上引入Ｃ－Ｏ－Ｃ,Ｃ－ＯＨ,Ｃ＝Ｏ,ＣＯＯＨ等含氧基团;辐照ＰＰ作为界面相容剂,能改善ＰＰ与玻纤间界面粘结状况,明显提高复合材料的层间剪切强度。     

改性三叶形聚乙烯醇纤维/环氧树脂复合材料的结构与性能

异形截面纤维大的比表面积有利于提高纤维与基体树脂间的界面结合,改善复合材料的强度和韧性.文中采用环氧氯丙烷对熔纺三叶形聚乙烯醇(PVA)纤维进行表面改性,通过模压成型首次制备了改性三叶形PVA纤维/环氧树脂复合材料.对比研究了改性前后三叶形PVA纤维表面结构和性能及对复合材料力学性能的影响.结果表明,改性后三叶形PVA纤维表面出现鳞状沟槽,粗糙度增加;纤维表面接枝了环氧官能团,与环氧预浸料的接触角减小,浸润性增加;表面接枝的环氧官能团参与了基体树脂的固化反应,单纤拔出力提高至3.61 N;改性三叶形PVA纤维/环氧复合材料的拉伸强度、弯曲强度和冲击强度分别为62.3 MPa,53.8 MPa和79.0 kJ/m2,比未改性三叶形PVA纤维/环氧复合材料分别提高了22.9％,134.9％和43.1％.     

改性木纤维对LDPE和木纤维复合材料力学性能的影响

研究了用改性钛酸酯类偶联剂ＴＣ－ＰＯＴ、ＴＣ－ＰＢＴ处理木纤维和接枝氰乙基改性未纤维对低密度聚乙烯（ＬＤＰＥ）／木纤维复合力学性能的影响,用改性钛酸酯类偶联剂处理木纤维可提高复合材料的拉伸强度、但大大降低了复合材料的拉伸断裂伸长率。而且接枝改性方法处理木纤维在使复合材料提高拉伸强度的同时,保持了较高的拉伸断裂伸长率。     

环氧氯丙烷对水溶性聚乙烯醇纤维的表面改性及增强机理

采用环氧氯丙烷通过溶胀悬浮多元接枝共聚法对水溶性聚乙烯醇(PVA)纤维进行表面改性,讨论了未改性和改性PVA纤维含量、环氧氯丙烷添加量、干燥温度、干燥时间及PVA纤维水溶温度对纸张干、湿拉力以及湿强度的影响。研究结果表明PVA纤维经环氧氯丙烷改性后,纸张的各项强度均有大幅提高,同时明显改善了其粘缸粘布行为和分散性。当干燥温度为100～110℃,干燥时间为10min,纤维水溶温度为80℃时,纸张具有较佳的强度。红外光谱图证实了环氧基团在原纤维表面的接枝改性反应。扫描电镜图表明PVA纤维经环氧改性后,表面由光滑结构转变为鳞状沟壑结构。原子力显微镜图AFM进一步说明了PVA纤维表面的亲水性基团部分被疏水性环氧基所取代,可增强纤维间的结合力。     

界面改性对GMT—PP复合材料力学性能的影响

研究了不同界面状态对ＧＭＴ－ＰＰ复合材料层间剪切强度,弯曲强度及模量,压缩强度及模量,冲击强度等力性能的影响。实验结果表明,基体中填加光引发和ＢＰＯ引发的马来酸酐接枝聚丙烯且玻纤表面用硅烷偶联剂处理可显著提高复合材料界面强度,进而提高其宏观力学性能。     

接枝偶联剂对F-12 纤维/环氧复合材料界面改性的研究

采用一种大分子接枝偶联剂对F-12 纤维表面进行等离子体接枝改性, 并采用ESCA 对改性后的纤维表面进行分析, 研究了接枝偶联剂的分子量和浓度对F-12/环氧复合材料横向拉伸强度的影响, 并结合横向拉伸的断口对改性机理进行了分析。实验结果表明: 接枝偶联剂接枝改性以后, 能够有效地改善F-12/环氧复合材料的界面结合状态, 从而提高复合材料的横向拉伸强度。      

SiC纤维／LCMAS微晶玻璃基复合材料的界面结合和力学性能

本工作通过在母体玻璃中引入ＭｇＯ后进行热处理得到一系列具有不同热膨胀系数的微晶玻璃．ＳｉＣ纤维／ＬＣＭＡＳ微晶玻璃基复合材料在烧结条件下，在纤维和基体间形成一厚度约为２μｍ的界面层．纤维、基体间的界面剪切应力通过单根纤维压出法测试，发现纤维、基体间的界面剪切强度对复合材料的力学性能有严重的影响，并且ＳｉＣ纤维／ＬＣＭＡＳ系微晶玻璃基复合材料具有较高的界面剪切强度，通过降低基体的热膨胀系数减弱界面剪切强度，可使复合材料的强度和断裂韧性都得到明显的改善．     

CaCl1和多巴胺处理对芳纶纤维表面结构与性能的影响

采用氯化钙(CaCl2)乙醇溶液和多巴胺水溶液浸渍法对芳纶纤维表面进行改性处理,对改性后芳纶纤维表面的化学结构、微观形貌、表面粗糙度、单丝拉伸强度和芳纶纤维/环氧树脂复合材料的界面性能等进行了测试分析.结果表明,采用CaCl2乙醇溶液处理芳纶纤维后,芳纶纤维表面有刻蚀出的沟槽,表面粗糙度增大,芳纶纤维/环氧树脂复合材料的层间剪切强度明显提高,同时由于纤维结构受到破坏,单丝拉伸强度下降了11.12％;采用多巴胺水溶液处理时,芳纶纤维表面沉积了聚多巴胺涂层,表面粗糙度增大,芳纶纤维/环氧树脂复合材料的层间剪切强度进一步提高,纤维结构几乎不受影响,单丝拉伸强度降幅较小;采用CaCl2乙醇溶液和多巴胺水溶液先后处理芳纶纤维后,纤维表面的聚多巴胺涂层更致密,复合材料的层间剪切强度达到最大值,同时改性后的纤维具有一定的抗紫外性能,此方法改性效果最优.     

γ射线辐照对碳纤维表面接枝改性的影响

为提高碳纤维/环氧树脂复合材料的界面粘结性能, 采用γ射线共辐照接枝方法对碳纤维表面改性, 利用X光电子能谱仪(XPS)、 扫描电子显微镜(SEM)、 电子万能材料试验机, 研究了在缩乙二醇丙酮溶液和环氧氯丙烷丙酮溶液中经200 kGy剂量的γ射线辐照接枝后, 碳纤维的表面化学元素及官能团组成、 表面形貌、 复合材料剪切断面形貌及其层间剪切强度(ILSS)的变化。研究表明, 缩乙二醇类接枝液的接枝效果较理想, 碳纤维接枝率达7%; 辐照处理碳纤维表面O/C比值和含氧官能团含量增加, 以此制备的碳纤维/环氧复合材料的ILSS提高, 最大提高率达31.2%; 同时还发现辐照接枝后的碳纤维表面粗糙度增大。     

The interfacial shear strength of Kevlar fiber/epoxy composite measured by the microdroplet test

Epoxy chloropropane (ECP) grafting modification method was used for the surface treatment of Kevlar fiber to improve the interfacial adhesion of the Kevlar fiber reinforced epoxy composite. The surface characteristics of untreated and treated Kevlar fiber were characterized by Fourier transform infrared (FT‐IR) spectroscope. The interfacial shear strength between epoxy and Kevlar fiber was analyzed by measuring from microdroplet specimens adhered onto a single carbon fiber. Microdroplet specimens exhibited different results of the interfacial strength due to the Kevlar fiber surface treatment. The results showed that a larger shear stress concentration arose along the interface for the surface treated model than for the untreated one.     

冷等离子体处理对PET纤维/环氧复合材料界面改性的研究

采用冷等离子体技术对PET纤维进行表面处理,并采用ESCA对处理前后的纤维表面进行了分析。研究了冷等离子体处理工艺参数对PET纤维/环氧复合材料界面剪切强度、横向拉伸强度的影响。实验结果表明:冷等离子体处理可以使PET纤维表面的氧和氮的极性基团含量增加,从而改善其与树脂的浸润性,进而改善PET纤维/环氧复合材料的界面性能。     

LiCl处理对芳纶纤维表面结构与性能的影响

为提高芳纶纤维与复合材料基体间的界面强度,首先,使用LiCl乙醇溶液处理芳纶纤维一定时间;然后,对LiCl处理芳纶纤维表面的化学组成、微观形貌、单丝拉伸强度及芳纶纤维/环氧树脂复合材料的界面性能等进行了测试分析。结果表明:使用LiCl乙醇溶液处理芳纶纤维后,芳纶纤维表面的含氮官能团含量增加;处理后,芳纶纤维表面有刻蚀出的沟槽,表面粗糙度增大,进而改善了芳纶纤维与环氧树脂基体的界面粘接性能,使芳纶纤维/环氧树脂复合材料的层间剪切强度由处理前的21.75 MPa提升到37.98 MPa;最佳处理时间为3~4 h,而处理时间过长会导致芳纶纤维的单丝拉伸强度及复合材料的层间剪切强度下降。所得结论证实使用LiCl处理芳纶纤维是一种有效的表面改性方法。      

Effect of γ-ray irradiation grafting on the carbon fibers and interfacial adhesion of epoxy composites

A special technique using γ-ray irradiation-induced graft-polymerization was applied to carbon fibers. Epoxy resin and chloroepoxy propane reacted with carbon fibers by a co-irradiation grafting method and acrylic acid was graft-polymerized onto the fiber surface via a pre-irradiation grafting method. The roughness, amount of containing-oxygen functional groups and surface energy were all found to increase significantly after irradiation grafting. Gamma-ray irradiation grafting improved marginally the tensile strength of carbon fibers, which was evaluated by statistical analysis using the Weibull distribution. The interlaminar shear strength of treated carbon fiber/epoxy was enhanced by at least 17.5%, compared with that of untreated carbon fiber/epoxy. The mechanisms of irradiation grafting are proposed by radical reactions. The γ-ray co-irradiation grafting and pre-irradiation grafting are both an effective method for modifying the physicochemical properties of carbon fibers and improving the interfacial adhesion of composites.     

Adhesion of PBO fiber in epoxy composites

A composite of poly p-phenylene-2,6-benzobisoxazole (PBO) fiber and epoxy resin has excellent electrical insulation properties. However, it is a challenging issue to improve its mechanical properties because of poor adhesion between PBO fiber and matrix. The relatively smooth and chemically inactive surface of PBO fiber prevent efficient chemical bonding in the composite interface. Here, we report the surface modification of PBO fibers by UV irradiation, O₂ and NH₃ plasma, as well as acidic treatments. We found that the surface free energy and roughness are increased for both sized and extracted fibers after plasma treatments together with maleic anhydride grafting. The sized fiber shows marginal improvement in adhesion strength and no change in fiber tensile strength because of the barrier effect of the finish. For the extracted fiber, however, the tensile strength of the fiber is sensitive to surface treatment conditions and considerable strength reduction occurred, particularly for cases of acidic treatments and UV irradiation. This is because that the treatments increase the surface roughness and introduce more surface flaws. The extracted fiber surface has no adequate wetting and functional groups, which in turn results in coarse interface structures and causes reduction or no apparent variation of the adhesion strength. The fracture surfaces after single fiber pull-out tests exhibit adhesive interfacial failure along the fiber surface, which is further confirmed by similar adhesion strength and interlaminar shear strength values when the fiber was embedded in various epoxy resins with different temperature behavior.     

Enhanced interfacial properties of domestic aramid fiber-12 via high energy gamma ray irradiation

The high energy irradiation was used to modify domestic aramid fiber-12 (DAF12) in epoxy chloropropane. The properties of the interphase between DAF12 and epoxy matrix systems were optimized. Scanning electron microscopy was employed to characterize the surface morphology of DAF12 and high energy irradiated fibers (HEI-DAF12) and composites de-bonding section. Atomic force microscopy showed the original smooth surface disappeared. Single fiber pull-out tests revealed that the interfacial shear strength of HEI-DAF12/epoxy composite was substantially improved by 45.17% after irradiation in 400 kGy dose. Dynamic contact angle analysis indicated the increased total surface free energy. The changes of elemental composition investigated via X-ray Photoelectron Spectrometer verified the increase polar groups on fiber surface caused by high energy irradiation.