耐高温环氧树脂胶粘剂的研究进展

对耐高温环氧树脂胶粘剂的研究进展进行了综述,分析了环氧树脂胶粘剂耐高温性的影响因素及提高环氧胶粘剂耐高温性的途径。重点阐述了几种提高环氧树脂胶粘剂耐温性的新方法,对其发展前景进行了展望。     

室温固化耐温200℃环氧树脂胶粘剂的研制

以高活性EP(环氧树脂)[即AFG-90(缩水甘油胺型EP)]为基体树脂、耐热的多官能度BTDA(3,3′,4,4′-二苯甲酮四酸二酐)为固化剂和ME-1为叔胺类促进剂,制备了一种室温固化型耐高温EP胶粘剂。采用差示扫描量热(DSC)法、凝胶试验和热失重分析(TGA)法研究了该胶粘剂的固化反应特性和热性能,并探讨了a∶e[即n(酸酐基团)∶n(环氧基团)]比值、促进剂含量等对该胶粘剂性能的影响。研究结果表明:该胶粘剂具有良好的耐高温性能,并且可室温固化,其25℃时的凝胶时间为80 min,失重5%时的温度为311℃;当a∶e=0.80∶1、w(ME-1)=1.0%(相对于EP质量而言)时,该胶粘剂的综合性能相对最好,其室温、200℃时的拉伸剪切强度(钢-钢)分别为21.86、18.55 MPa。     

短切玻璃纤维毡用固体胶粘剂的实验研究

本文介绍了短切原丝毡用粘结剂的合成工艺及性能。试用表明：该不饱和聚酯树脂性能优良，完全适合短切毡成型工艺要求。     

双马来酰胺改性环氧树脂胶粘剂的研究

以双来酰亚胺、环氧树脂和芳香二胺为主要原料,利用ＢＭＩ的耐高温性能,在保证环氧高强度的基础上,对环氧胶粘剂进行改性。重点讨论了加料试、组成性能的影响。可制得强度保持在３０ＭＰａ左右的耐高温胶。     

短切纤维增强环氧树脂力学性能研究

采用熔融共混工艺制备了短切碳纤维（SCF）和无碱玻璃纤维（SGF）填充TDE-85环氧树脂（EP）复合材料。研究了不同纤维用量对复合材料力学性能的影响;利用扫描电子显微镜（SEM）考察了材料冲击断口的显微结构和断裂形态。研究表明：两种短切纤维增强TDE-85环氧树脂复合材料的力学性能整体趋势相似;纤维质量分数低于20％时,SCF增强复合材料的各项力学性能均优于SGF增强复合材料。而SGF增强复合材料的综合力学性能在纤维质量分数为30％时达到最高。     

环氧树脂液体胶粘剂耐高温性能分析

环氧树脂液体胶粘剂存在不耐高温的问题.以环氧树脂为基料,通过加入聚芳醚腈、碳硼烷以及聚氨酯等三种不同的改性物质,制成三种不同类型的环氧树脂液体胶粘剂,并针对这三种胶粘剂,分析环氧树脂液体胶粘剂耐高温性能.结果表明:通过高温下热重测试,碳硼烷-环氧树脂胶粘剂的表观分解温度和温度指数最高,分别为850.3℃和23.54℃,...     

短切碳纤维增强环氧树脂复合材料的研究

采用冷模压成型工艺制备了短切碳纤维增强环氧树脂(SCFRER)复合材料,并对复合工艺参数进行了讨论。借助于金相显微镜研究了SCFRER复合材料的微观结构特征;较全面地研究了短碳纤维(SCF)含量对复合材料的热、电性能和力学性能(拉伸、弯曲和压缩强度)的影响。     

耐高温环氧树脂胶粘剂研究进展

介绍了近年来耐热环氧树脂胶粘剂的研究概况 ,讨论了影响环氧树脂胶粘剂耐热性的因素 ,并指出了耐热环氧树脂胶粘剂的研究发展方向。     

耐高温环氧树脂胶粘剂的研究进展

介绍了耐高温环氧树脂(EP)胶粘剂中无机填料、热塑性树脂、酚醛树脂(PF)、纳米粒子和结构调整等EP改性方法的研究进展,特别对双马来酰亚胺(BMI)改性EP及有机硅改性EP进行了综述。最后对耐高温EP胶粘剂的发展前景进行了展望。     

玻璃纤维增强环氧树脂基复合材料的性能研究

本研究以玻璃纤维作为增强体,环氧树脂作为基体,甲基四氢苯酐为固化剂,制备了玻璃纤维/环氧树脂基复合材料。力学性能测试和热性能测试结果表明:玻璃纤维的含量为1wt%时,可以提高环氧树脂复合材料的韧性和强度,同时提高了玻璃化转变温度。     

短玻纤增强ABS复合材料的研制

介绍短玻纤维增强ABS复合材料的生产工艺,实验对比了处理玻纤用偶联剂种类和加入量、玻纤含量、ABS种类及抗冲改性剂加入量对复合材料性能的影响,结果表明,玻纤用质量分数为1.5%的偶联剂KH550处理,可增强9715A ABS,同时加入质量分数为2%抗冲改性剂的可得到综合性能较好的复合材料。     

耐溶剂高温快速固化EP胶膜的研制

以双酚A型环氧树脂(EP128、EP301)为基体树脂、聚氨酯热熔胶(PU-HMA)为增韧剂、双氰胺(DICY)为固化剂、2-乙基-4-甲基咪唑(2E4MZ)为固化促进剂和硅微粉为填料,制备耐溶剂高温快速固化EP胶膜。研究结果表明:采用单因素试验法优选出制备耐溶剂高温快速固化EP胶膜的最佳工艺条件是w(PU-HMA)=20%、w(DICY)=12%、w(2E4MZ)=0.8%、w(硅微粉)=20%(均相对于EP质量而言)、m(EP 128)∶m(EP 301)=1∶1、固化温度为210℃和固化时间为100 s,此时EP胶膜的耐溶剂性(90 s)相对最好、粘接强度(40.22 MPa)相对最大。     

Modulus of short carbon and glass fiber reinforced composites

A theoretical model for a short fiber reinforced composite is proposed. The composite is assumed to consist of an aggregate of sub-units, each sub-unit possessing the elastic properties of a reinforced composite in which the fibers are continuous and fully aligned. The elastic constants of a partially oriented composite are then calculated by the Voigt and Reuss averaging procedures, giving upper and lower bounds respectively for the composite modulus. Comparison is made with experimental data for such composites. The measured modulus of glass and carbon fiber composites is found to be given by the Reuss or lower bound, to a good approximation compared with the difference between the bounds, for fiber orientations ranging from almost isotropic to highly aligned.     

Elongational behavior of short glass fiber reinforced polypropylene melts

The Rheometrics Elongational Rheometer was employed to study the uniaxial extensional flow of glass fiber filled polypropylene melts, in which the fiber concentration, c, varied between zero and 40 weight percent. The constant strain rate mode was used for strain rates, \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \varepsilon \limits^. $\end{document}, between 0.003 and 0.6 s⁻¹. Steady state elongational viscosities were observed in most cases for fiber filled polypropylene melts, even at rates at which the stress continued to increase for unfilled polypropylene. The rate of relative stress growth increased with \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \varepsilon \limits^. $\end{document} and was affected by the addition of fibers. The steady elongational viscosity of the fiber reinforced melts was found to decrease with increasing \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \varepsilon \limits^. $\end{document} and to increase with increasing c. Yield stresses were observed in elongational flow at high concentrations, although there was no clear evidence of yield in steady shear.     

Study on microfracture mechanism of short glass fiber reinforced polycarbonate by using acoustic emission

The influence of the difference in wettability between glass fiber (GF) and polycarbonate (PC) on the microfractures of GF reinforced PC was investigated by using an acoustic emission (AE) method. In the case of well‐coupled GF‐reinforced PC, it is suggested that in the AE amplitude region higher than about 16 mV, microfracture related to scission of polymer chains occurs at the interfacial layer between GF and PC. On the other hand, in the case of poorly‐coupled GF‐reinforced PC under stress, debonding and interfacial slippage between GF and PC occurred below the yield stress of PC, whereas interfacial fracture and GF breakage occurred above the yield stress. Debonding and interfacial slippage between GF and the PC matrix were closely related to an AE amplitude smaller than about 16 mV. The relationship between stress and AE events is expressed in this case by the Eyring model. The activation energy of interfacial slippage between GF and PC was about 74 kJ/mol, which corresponds to the energy of chain‐backbone motion of PC in the glassy state. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45664.     

Influence of fiber orientation,temperature and relative humidity on the long-term performance of short glass fiber reinforced polyamide 6

As a result of processing of short fiber reinforced thermoplastics, the fiber orientation varies throughout a product giving rise to a pronounced anisotropic mechanical response. Different flow conditions in a product result in spatial variation in both short- and long-term mechanical properties. In this study, a modeling approach is presented to evaluate the lifetime of short fiber reinforced polyamide 6, both in plasticity- and crack growth controlled regions of failure. In the plasticity-controlled region, a viscoplastic model based on separation of the load angle (by means of Hill's equivalent stress formulation) and time dependence of the yield stress is used in the form of an associative flow rule. The influence of temperature and relative humidity on the magnitude of the plastic flow rate is described by using an apparent temperature approach combined with a Ree-Eyring formulation. The depression of the glass transition temperature in the polyamide 6 matrix with increasing amount of absorbed moisture was used to predict the anisotropic deformation kinetics in a humid environment. Similar to the plasticity controlled failure, in slow crack growth controlled failure region the effect of temperature, relative humidity, and load angle on the lifetime under a fatigue load is investigated. The apparent temperature approach could also be successfully applied to predict the slow crack growth failure, while the load angle dependence is shown to scale similar to the plasticity-controlled failure with the Hill's equivalent stress.     

Influence of screw configuration and processing temperature on the properties of short glass fiber reinforced polypropylene composites

Short glass fiber reinforced polymers are used in many different applications due to their good property profiles. These properties are directly correlated with the fiber length present in the final composite, which can be influenced through the process. Therefore, the aim of this work was to investigate the influence of processing temperature and screw configuration in compounding on the properties of glass fiber reinforced polypropylene. On the one hand, the barrel temperature was varied between 180°C and 260°C and, on the other hand, four different screw configurations were applied using a standard temperature profile. Specimens were produced by injection molding, which were tested via mechanical characterization, density, and fiber length measurements as well as morphology through microscopical analysis. We found, that with higher barrel temperatures and screw configurations bringing lower shear into the melt the glass fiber length is preserved better, thus resulting in improved composite properties. Also the interfacial interaction is not influenced within the investigated parameters, as was checked via the application of a micromechanical model in composite strength. POLYM. ENG. SCI., 59:1552–1559 2019. © 2019 Society of Plastics Engineers     

Impact behavior of a short glass fiber reinforced thermoplastic polyurethane

The temperature dependence of critical strain energy release rate (G_c′) and standardized Charpy notched impact strength (CNIS) were measured for a thermoplastic polyurethane (TPUR) reinforced with 30 wt% of short glass fibers (SGF) over a temperature interval ranging from −150°C 23°C (RT) at two strain rates, 70 and 150 s⁻¹, respectively. Fractographic observation of fracture planes was used to qualitatively assess the fracture modes and mechanisms. Adhesion between the reinforcement and the matrix was excellent and the integrity of the fiber‐matrix interfacial contact was relatively insensitive to exposure to hydrolysis during the immersion in boiling water for 100 hours. At temperatures above −30°C, there was a large extent of plastic deformation in the vicinity of crack planes while at temperatures below −50°C, the extent of plastic deformation was substantially reduced. This resulted in a change in the major energy dissipation mechanism and led to a decrease of both CNIS and G_c′ values for SGF/TPUR composites. It was suggested that the plastic deformation of TPUR matrix in the immediate vicinity of glass fibers was the primary source of energy dissipation at temperatures above −30°C, while the friction and fiber pull‐out was the main dissipative process below −50°C. Over the whole temperature interval investigated, greater G_c′ values were obtained at higher strain rate of 150 s⁻¹, without any significant change in the fractographic patterns observed on the fracture planes. The CNIS/G_c′ ratio, used to assess suitability of CNIS for comparison of materials, changed with temperature substantially suggesting that the functional dependences of CNIS and G_c′ on temperature differ substantially. Hence, CNIS data do not provide a reliable base for material selection and for design purposes in this case.     

Shear and extensional properties of short glass fiber reinforced polypropylene

Shear and extensional properties of a commercial short glass fiber reinforced polypropylene were carefully investigated using commercial rheometers and a novel on‐line rheometer. This on‐line slit rheometer, installed on an injection molding press, has been designed to measure the steady shear viscosity, the first normal stress difference, and the apparent extensional viscosity of polymer melts and composites for high strain rates up to 10⁵ s⁻¹ in shear and 200 s⁻¹ in extension. Our results show that the steady‐state viscosity measurements using the on‐line rheometer are in excellent agreement with those obtained using commercial rheometers. The steady‐state and the complex viscosities of the composites were found to be fairly close to that of the matrix, but the Cox‐Merz rule was not verified for the composites at high rates. The elasticity of the composites was found to be equal to that of the polypropylene matrix. The apparent extensional viscosity was obtained from the pressure drop in the planar converging die of the slit rheometer using the analyses proposed by Cogswell [1] and Binding [2]. The extensional viscosity of the polypropylene was found to be much larger than the shear viscosity at low strain rates with a Trouton ratio of about 40 that decreased rapidly with increasing strain rate down to the value of 4 at 200 s⁻¹. The extensional viscosity of the composites was also found to be close to that of the matrix, with values 35 and 5% larger for the 30 and 10 wt% reinforced polypropylenes, respectively. These results are compared with the predictions of the Goddard model [3], which are shown to overpredict our experimental results. POLYM. COMPOS. 26:247–264, 2005. © 2005 Society of Plastics Engineers.     

Mechanisms of fatigue in short glass fiber reinforced polyamide 6

An adaptation to existing failure models for fatigue fracture of short fiber reinforced thermoplastics is presented, based on results using some new experimental methods. These results lead to the following conclusion: Cracks in polyamide remain bridged (by plastically drawn matrix material and/or fibers) until just before final fracture. Important is the conditioning of the polyamide: conditioned to equilibrium water content, this mechanism occurs, but not when it is dry as molded. Fatigue damage measurements were done on thin foils cut from the fatigued specimen. When tensile tested, these foils show a change in both strength and fracture strain after fatigue. Further observations during the experiments and SEM fractography strengthen the conviction that fatigue damage initiates and grows in the form of bridged cracks. A correlation between tensile strength and fatigue strength was found; the degree of fiber alignment has a similar effect on both tensile and fatigue properties.