傅-克烷基化反应改性芳纶纤维对EPDM绝热层力学性能的影响

以傅瑞德-克拉夫茨(Friedel-Crafts)反应为基础,活化处理芳纶纤维的惰性表面,将改性纤维大量加入到EPDM制备成绝热层。采用红外、X-射线能谱仪、扫描电镜检测活化处理对芳纶纤维表面的改性效果,并测试EPDM绝热层的力学性能和动态力学性能。研究结果表明,纤维经过活化处理加入EPDM绝热层后,断裂伸长率提高了68.0%,拉伸强度下降了18.6%,同时弹性模量和黏性模量均增加。     

表面处理对三元乙丙橡胶室温粘接性能影响

主要研究了紫外线、臭氧和紫外线 臭氧三种表面处理方法对三元乙丙橡胶室温粘接性能的影响.实验结果表明,当处理时间适当时,粘接试样的拉伸剪切强度均有所提高,其中紫外线处理提高幅度最大,约35%.经扫描电镜,表面光电子能谱分析表明,3种表面处理方法均可在三元乙丙橡胶的表面引入活性基团,改善表面的低活性.     

软木纤维增强PP复合材料的研究

采用软木纤维作为增强材料提高聚丙烯性能。为了改善软木纤维和聚丙烯母体之间的相容性,用马来酸酐接枝聚丙烯(MAPP)对软木纤维进行接枝处理,用MAPP或用三元乙丙橡胶(EPDM)对软木纤维进行改性处理。结果表明,与未经处理木纤维的复合材料相比,三种处理方法都使复合材料的热性能、加工性能和力学性能有了较大的提高。用MAPP接枝和用MAPP表面处理木纤维的方法比用EPDM表面处理木纤维的方法在提高复合材料热性能、加工流动性和拉伸强度方面更为显著。用EPDM表面处理木纤维在改善复合材料的冲击强度、断裂伸长率上更明显。此外,木纤维在复合材料中的浓度对复合材料其它性能的影响,以及MAPP接枝木纤维和MAPP处理木纤维的不同实验结果也进行了评价。     

Kevlar纤维的表面改性研究

采用甲苯-2,4-二异氰酸酯(TDI)和环氧树脂(EP)混合制得的表面改性剂对Kevlar纤维进行表面接枝处理,利用扫描电子显微镜观察Kevlar纤维改性前后的表面形貌及改性Kevlar纤维与弹性体间剥离界面的破坏形貌,用衰减全反射傅里叶变换红外光谱仪分析Kevlar纤维改性前后表面化学基团的变化,研究了改性效果和机理。结果表明,TDI和EP发生了化学反应,改性剂可在Kevlar纤维表面引入活性基团,从而显著改善了Kevlar纤维与聚合物基体之间的界面粘合状态。     

硫酸钙晶须改性三元乙丙橡胶的性能研究

近年来三元乙丙用量有逐渐增加的趋势,因此对于三元乙丙橡胶的改性研究也越来越多,文章采用了一种新型填充材料硫酸钙晶须对三元乙丙橡胶进行改性,研究了硫酸钙晶须用量、硫化工艺条件和偶联剂对三元乙丙橡胶力学性能的影响。结果表明,提高硫酸钙晶须的用量,采用二段硫化和加入KH-550,均能提高三元乙丙橡胶的拉伸强度,同时也能改善其它力学性能。     

芳纶纤维的活化浸渍处理对EPDM绝热层力学性能的影响

采用TDI(甲苯-2,4-二异氰酸酯)、IPDI(异佛尔酮二异氰酸酯)两种不同异氰酸酯对芳纶纤维进行活化处理,并用RFL(间苯二酚-甲醛-胶乳)浸渍液处理,将改性纤维大量加入到EPDM(三元乙丙橡胶)制备成绝热层。利用红外分析芳纶纤维表面处理后官能团的变化,用EDS分析纤维表面元素含量,用SEM观察纤维表面的形貌,通过拉力测试仪测试了绝热层的力学性能。研究发现纤维经过TDI活化并浸渍RFL后,改性效果更好,EPDM绝热层的断裂伸长率提高了53%,抗拉强度降低了9.7%,模量升高了24.3%。     

尼龙6改性研究

采用经化学改性的芳纶纤维增强尼龙6,并通过红外光谱和电镜分析其界面层,结果表明芳纶纤维经异氰酸酯化及封端稳定处理后,其表面所接技的不稳定基团-NCO转化成稳定的-NHCO-,封端结果较为明显;改性后纤维表面附有接枝物,从而使表面粗糙程度大大增加。用挤出和注塑的方法加工了PA6／Kevlar纤维（KF）复合材料,研究了它的拉伸、弯曲和冲击性能破坏形态。力学性能测试表明了改性尼龙6复合材料的拉伸和弯曲强度得到了改善,但冲击性能略为下降。     

含溴阻燃剂/三元乙丙橡胶绝热层性能研究

研究了含溴阻燃剂对三元乙丙橡胶绝热层烧蚀性能、力学性能影响。结果表明,高纤维含量绝热层的烧蚀率与伸长率随阻燃剂用量增加呈上升趋势;增加阻燃剂用量可以改善低纤维含量绝热层伸长率及烧蚀性能。     

PBO纤维表面改性及其与树脂基体界面性能研究

分别采用化学处理、等离子体处理、偶联剂处理、γ射线辐照等单一改性方法和“辐照+等离子体”、“辐照+等离子体+偶联剂”等综合改性方法对PBO纤维进行表面处理,之后对各种不同方法改性后的纤维进行了单丝拉伸强度、与树脂的接触角和单丝拔出性能测试.结果表明,经综合改性方法处理后的PBO纤维综合性能最优,单丝拉伸强度保持率为85.1％,与水的接触角达到74.15°;与未经表面处理的纤维相比,其与树脂基体间的粘结强度提高了48.6％.     

磷酸表面改性Kevlar纤维及其复合材料性能的研究

采用磷酸溶液对芳纶纤维(Kevlar)进行了表面改性,通过考察其表面化学结构、元素组成、表面形貌及表面粗糙度的变化研究了磷酸对Kevlar纤维表面改性的效果.结果发现,改性后的纤维表面引入了含氧基团,并产生了明显的刻蚀作用.利用溶液预浸渍工艺和高温模压成型技术制备了Kevlar增强双马来酰亚胺树脂(BMI)复合材料,通...     

Graft copolymerization of ϵ-Caprolactam onto Kevlar-49 fiber surface and properties of grafted Kevlar fiber reinforced composite

The anionic graft copolymerization of ϵ-caprolactam onto a Kevlar-49 fiber surface was carried out by using a metalation reaction in a dimethyl sulfoxide solution of sodium hydride. The effects of reaction conditions on the graft yield and on the tensile strength of the fiber have been investigated. Graft yield significantly increased with increasing metalation time, NaH concentration, and monomer concentration. The graft yield varied from 6 to 32% with reaction conditions. The tensile strength of the fiber depended predominantly on NaH concentration. The retained tensile strength was over 93% when the concentration of NaH was below 2.1 mmol/L per 0.5 g of Kevlar. The discontinuous Kevlar fiber reinforced composites were prepared by a blending/melt-pressing method. In thermomechanical and dynamic mechanical analyses, the relaxation peak of grafted Kevlar fiber/Nylon 6 composite film moved to higher temperatures, compared with the original Kevlar fiber/Nylon 6 composite film. The grafted Kevlar fiber reinforced Nylon 6 composite film exhibited mechanical properties superior to those of the original Kevlar fiber reinforced composite film. The higher thermal and mechanical properties were due to the effect of higher interfacial interaction between the grafted Kevlar fiber and matrix. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 99–107, 1997     

Kevlar 49纤维与芳纶Ⅲ的结构与性能研究

借助傅立叶变换红外光谱仪、扫描电子显微镜、X射线光电子能谱仪和强力拉伸仪分析研究了Kevlar 49和芳纶Ⅲ的化学结构、表面特征及力学性能。结果表明:芳纶Ⅲ的红外谱图上多出了苯并咪唑环的吸收峰;芳纶Ⅲ的表面较粗糙,Kevlar 49表面较光滑,芳纶Ⅲ和Kevlar 49纤维表面的碳、氧元素均比化学式计算值有所增加,但氮元素含量下降;芳纶Ⅲ表面的极性基团种类比Kevlar 49多。芳纶Ⅲ的单纤维拉伸强度是Kevlar 49的1.5倍,断裂伸长率比Kevlar49提高了45%～65%;2种纤维的断裂方式均为劈裂断裂,具有皮芯结构,但芳纶Ⅲ分子间的作用力比Kevlar49纤维强。     

Surface modification of Kevlar by grafting carbon nanotubes

A novel and efficient method was developed for surface‐modification of Kevlar fibers by multi‐wall carbon nanotubes (MWCNTs). Kevlar fibers were immersed in a solution mixed with Hexamethylene diisocyanate, 1,4‐diazabi‐cyclo [2,2,2] octane (DABCO), and toluene to introduce pendant amine groups before the COCl‐functionalized carbon nanotubes were chemically grafted onto the surface of modified fibers under ultrasonic condition. The characterization of resulting fiber involved in SEM, infrared spectroscopy, and tensile measurement. Results indicated over 20% of the fiber surface were coated by MWCNTs even after washing, which indicated a good adhesion. Furthermore, the mean value of tensile strength of Kevlar fiber was improved by 12% compared with original one. And the interlaminar shear strength (ILSS) of the fiber‐reinforced bismaleimides composite was increased by 30%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Experimental investigation on fatigue property at room temperature of C/SiC composites machined by rotary ultrasonic milling

Rotary ultrasonic milling technology (RUM), as a surface strengthening machining method, was proposed to utilize in processing of C/SiC composites for enhancing anti-fatigue performance innovatively. Static tensile, intermittent fatigue and residual strength test were carried out. Due to constant impingement of high-frequency and low-amplitude vibration, surface residual compressive stress was formed near 2 GPa maximally. Axial thermal residual stress in fiber achieved -662.4 MPa proved by loading-unloading test. The peak value of fatigue damage parameter was reduced significantly. RUM surface restrains most of interface cracks because of residual compressive stress, and hinder the growth of fiber cracks for better machined surface quality. The damage accumulation, the first stress redistribution and fiber reinforcement stage were delayed. Average damage rate was decreased by 80.5 %. Residual tensile strength of RUM C/SiC was improved after fatigue, up to 95.8 % of tensile strength. The strengthening effect from RUM on fatigue property of C/SiC is significant and valuable.     

Influence of Fiber Surface Modification on the Mechanical Performance of Isora-Polyester Composites

This paper reports the effect of chemical treatment on the mechanical properties of a natural fiber, isora, as reinforcement in unsaturated polyester resin. Isora fiber is separated from the bark of the Helicteres isora plant by a retting process. The short isora fiber surface was modified chemically by acetylation, benzoylation, silane and triton treatments to bring about improved interfacial interaction between the fiber and the polyester matrix. The modified surfaces were characterized by IR spectroscopy and SEM. The SEM studies were carried out to investigate the fiber surface morphology, fiber pull-out and fiber-polyester interface bonding. They showed the changes occuring on the fiber surface during chemical treatment. Properties like tensile strength, flexural strength and impact strength have been studied. The chemical modification of fiber improved fiber/matrix interaction as evidenced by the enhanced tensile and flexural properties. The lower impact properties of the composites, except triton-treated fiber composite, further point to the improved fiber/matrix adhesion, compared to the untreated fiber composites.     

三维编织芳纶纤维增强尼龙复合材料性能研究术

研究了纤维体积比对三维编织芳纶纤维增强尼龙(简称K3D／PA)复合材料力学性能的影响。同时，研究了γ射线辐照处理对K3D／PA的影响。研究发现，随着芳纶纤维体积比的增大，K3D／PA的力学性能提高；芳纶纤维经γ射线辐照处理后，表面含氧量有所提高，并出现新的官能团。纤维经表面处理后，K3D／PA的弯曲强度、弯曲弹性模量及剪切强度均比未处理的高，但冲击强度较低。     

Pultruded fiber reinforced thermoplastic poly(methyl methacrylate) composites. Part II: Mechanical and thermal properties

A novel process has been developed to manufacture poly(methyl methacrylate) (PMMA) pultruded parts. The mechanical and dynamic mechanical properties, environmental effects, postformability of pultruded composites and properties of various fiber (glass, carbon and Kevlar 49 aramid fiber) reinforced PMMA composites have been studied. Results show that the mechanical and thermal properties (i.e. tensile strength, flexural strength and modulus, impact strength and HDT) increase with fiber content. Kevlar fiber/PMMA composites possess the highest impact strength and HDT, while carbon fiber/PMMA composites show the highest tensile strength, tensile and flexural modulus, and glass fiber/PMMA composites show the highest flexural strength. Experimental tensile strengths of all composites except carbon fiber/PMMA composites follow the rule of mixtures. The deviation of carbon fiber/PMMA composite is due to the fiber breakage during processing. Pultruded glass fiber reinforced PMMA composites exhibit good weather resistance. They can be postformed by thermoforming, and mechanical properties can be improved by postforming. The dynamic shear storage modulus (G′) of pultruded glass fiber reinforced PMMA composites increased with decreasing pulling rate, and G′ was higher than that of pultruded Nylon 6 and polyester composites.     

T700碳纤维/环氧树脂复合材料热降解实验研究

针对T700碳纤维增强环氧树脂复合材料的热降解行为以及回收所得碳纤维的力学性能进行了研究。研究结果表明,碳纤维的存在增加了环氧树脂降解时所需的活化能,热降解反应的温度、时间和气氛等因素对环氧树脂基体降解效果以及回收碳纤维力学性能均有影响。在空气条件下500℃处理30 min后碳纤维表面没有残留物,但其回收纤维的拉伸强度保留率仅为77.6%。通过首先在氮气气氛高温短时热处理,再在空气气氛下450℃进行30 min热降解的两步法处理后,碳纤维表面残炭得到去除,回收碳纤维的拉伸强度保留率达到了90.4%,由其制备单向复合材料的层间剪切强度保留率可达到75.8%。