Contrast on tensile and flexural properties of glass powder reinforced epoxy composites: Pilot study

Epoxy resin was filled with glass powder to optimize the tensile and flexural strength of the composite for structural applications by a research center in the University of Southern Queensland (USQ). To reduce costs, the center wishes to fill as much glass microspheres as possible subject to maintaining sufficient strength of the composites in structural applications. This project varies the percentage by weight of the glass powder in the composites. After casting the composites to the molds, they were cured at ambient conditions for 24 h. They were then postcured in a conventional oven and subjected to tensile and flexural tests. The contribution of the study was that if tensile and flexural properties were the most important factors to be considered in the applications of the composites, the maximum amount of glass powder can be added to the resin will be five (5) percent. It was also found that the fractured surfaces examined under scanning electron microscope were correlated with the tensile and flexural strength It is also hoped that the discussion and results in this work would not only contribute toward the development of glass powder reinforced epoxy composites with better material properties, but also useful for the investigations of tensile and flexural properties in other composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Chemical recycling of glass fiber reinforced epoxy resin cured with amine using nitric acid

An approach to chemical recycling of amine cured epoxy resin using nitric acid solution has been proposed [Dang W, Kubouchi M, Yamamoto S, Sembokuya H, Tsuda K. Polymer 2002;43:2953-8. [1]]. 1,8-p-Menthanediamine cured bisphenol F type (BPF/MDA) epoxy resin was decomposed in nitric acid solution, and then the decomposed product was repolymerized with original resin. In this paper, applicability of the proposed approach to glass fiber reinforced bisphenol F type epoxy resin cured with diamino diphenyl methane (DDM) was investigated. It was concluded that the approach was applicable to BPF/DDM epoxy resin, and potentially to all of amine cured epoxy resin. Flexural strength of the recycled resin was higher than that of virgin resin until the content of the neutralized extract, which was available from degradation of BPF/DDM epoxy resin, was not more than 30 wt% of the original resin. The reinforcement of glass fiber could be separated and recovered. The existence of the reinforcement did not affect decomposition the matrix.     

微脱黏法在碳纤维/环氧树脂界面性能评价中的应用

利用微脱黏法测定碳纤维/环氧树脂复合材料的界面剪切强度,并分析了造成测试结果分散的影响因素.结果表明:在脱黏过程中,最大脱黏力随碳纤维埋人环氧树脂内长度的增加而线性递增,当埋人长度超过一定值后最大脱黏力趋于稳定:碳纤维与环氧树脂间的接触角对复合材料界面剪切强度有一定影响,接触角越大,界面剪切强度越高;测试结果的分散性与树脂微球的半月板区域、钳口区等因素有关;未经表面处理的碳纤维增强环氧树脂复合材料的界面剪切强度仪为39.4 MPa,低于处理后的复合材料(60.6 MPa).     

Influence of silicon carbide filler on mechanical and dielectric properties of glass fabric reinforced epoxy composites

Fiber‐reinforced polymeric composites (FRPCs) have emerged as an important material for automotive, aerospace, and other engineering applications because of their light weight, design flexibility, ease of manufacturing, and improved mechanical performance. In this study, glass‐epoxy (G‐E) and silicon carbide filled glass‐epoxy (SiC‐G‐E) composite systems have been fabricated using hand lay‐up technique. The mechanical properties such as tensile strength, tensile modulus, elongation at break, flexural strength, and hardness have been investigated in accordance with ASTM standards. From the experimental investigations, it has been found that the tensile strength, flexural strength, and hardness of the glass reinforced epoxy composite increased with the inclusion of SiC filler. The results of the SiC (5 wt %)‐G‐E composite showed higher mechanical properties compared to G‐E system. The dielectric properties such as dielectric constant (permittivity), tan delta, dielectric loss, and AC conductivity of these composites have been evaluated. A drastic reduction in dielectric constant after incorporation of conducting SiC filler into epoxy composite has been observed. Scanning electron microscopy (SEM) photomicrographs of the fractured samples revealed various aspects of the fractured surfaces. The failure modes of the tensile fractured surfaces have also been reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

An impact study of epoxy resin composites reinforced with glass fiber fabrics

The impact properties of epoxy resin composites reinforced with three types of fabrics which are welf-knitted structural fabrics (WKSF), three-dimensional fabrics (3D-3A & 3D-5A) and plain-weave structural fabrics (2D-2A) have been investigated. The results of experiments show that WKSF composite has total impact energy about 1.5 and 3.5 times those of 3D and 2D fabrics composite respectively. The ductility index of WKSF is about 2.2 times of those of 3D and 2D. WKSF composites are very ductile materials and can absorb much more impact energy than 3D and 2D composites. The pushed-out volume of WKSF composites after the impact test was calculated from the photographs and the results show that the volume of the pushed-out zone is proportional to impact energy.     

纳米氮化硅对环氧树脂固化反应的影响研究

通过DSC、红外光谱研究了纳米氮化硅粒子的加入对环氧树脂体系固化反应的影响。结果表明,一方面由于纳米Si3N4高的表面活性会促进环氧树脂体系的固化过程;另一方面,由于纳米粒子的加入增大了体系的粘度阻碍了反应分子的运动使得复合材料固化反应速度变慢。环氧树脂体系在不同反应时期表现出的不同的固化行为正是这两种因素综合作用的结果。此外,还研究了不同添加量的纳米Si3N4对复合材料拉伸强度和固化时间的影响。当纳米Si3N4添加量为3%(以环氧树脂质量计)时,复合材料拉伸强度达到最大值,提高了145%。     

双邻苯二甲腈改性环氧及其玻纤复合材料制备

采用双邻苯二甲腈树脂(BAPh)对环氧树脂E-44(EP)进行改性,同时制备了BAPh/EP/玻纤复合材料。采用示差扫描量热仪,热重分析,力学性能测试及氧指数仪研究了改性树脂的热性能、力学性能及阻燃性能,并对BAPh/EP/玻纤复合材料的力学性能进行了表征。结果表明,当BAPh质量分数达到50%时,改性树脂固化物在空气中的起始分解温度达到377.6℃,比纯环氧提高74.3℃,氧指数达到34.5%,复合材料的弯曲性能指标达到最大,添加双邻苯二甲腈后环氧树脂的耐热性、力学性能和阻燃性能得到了明显改善。     

环氧树脂/黏土纳米复合材料研究进展

综述了目前环氧树脂/黏土纳米复合材料的制备方法和表征手段,介绍了环氧树脂/黏土纳米复合材料的优异性能,并对其增韧增强改性机理作了探讨,最后展望了环氧树脂/黏土纳米复合材料的应用前景。     

Effect of g-C3N4 nanofiller as filler on mechanical properties of multidirectional glass fiber epoxy hybrid composites

An experimental study was carried out to investigate the flexural strength of glass-fiber-reinforced (multidirectional woven glass fiber) epoxy hybrid composites filled with different proportions (1, 1.5, 2, 2.5, and 3%) of graphitic carbon nitride (g-C₃N₄) filler. g-C₃N₄ powder filled glass epoxy composites were fabricated in conventional hand lay-up method. Results showed an increase in flexural strength of g-C₃N₄ particles content by 2% and beyond which the strength decreased. With the addition of 2 wt % of g-C₃N₄ in glass-fiber-reinforced epoxy composites, the tensile strength increased by 11% and the flexural strength increased by 13%. The eroded surface of the specimen was observed under scanning electron microscope and the results are reported. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48413.     

Surface modification of PBO fibers by argon plasma and argon plasma combined with coupling agents

The methods of argon plasma and argon plasma combined with coupling agents were employed to modify the poly[1,4‐phenylene‐cis‐benzobisoxazole] (PBO) fiber surface. The interfacial shearing strength (IFSS) of PBO fibers/epoxy resin was measured by the single fiber pull‐out test. The surface chemical structure and surface composition of PBO fibers were determined by FTIR and X‐ray photoelectron spectroscopy respectively. The morphology of the fiber surface was investigated by scanning electron microscopy and the specific surface area of the fibers was calculated by B.E.T. equation. Furthermore, the wettability of PBO fibers was confirmed by the droplet profile analysis method. The results showed that the elemental composition ratio of the fiber surface changed after the modification. The IFSS increased by 42 and 78% when the fibers were treated by argon plasma and argon plasma combined with the coupling agents, respectively. Meanwhile, the specific surface areas of the treated fibers were improved. In addition, compared with the modification of argon plasma, the modification of argon plasma combined with the coupling agents inhibited the attenuation phenomena of the IFSS and the wettability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1428–1435, 2006     

Influence of moisture regain of aramid fibers on effects of atmospheric pressure plasma treatment on improving adhesion with epoxy

One difference between a low‐pressure plasma treatment and an atmospheric pressure plasma treatment is that in the atmosphere, the substrate material may contain significant quantities of moisture, which could potentially influence the effects of the plasma treatment. To investigate how the existence of moisture affects atmospheric pressure plasma treatment, aramid fibers (Twaron 1000) with three different moisture regains (0.5, 4.5, and 5.5%) were treated by an atmospheric pressure plasma jet for 3 s at a gas flow rate of 8 L/min, a treatment head temperature of 100°C, and a power of 10 W. The scanning electron microscopy analysis showed no observable surface morphology change for the plasma treated samples. X‐ray photoelectron spectroscopy analysis showed the oxygen contents of the 0.5 and 4.5% moisture regain groups increased from that of the control, although the opposite was true for the 5.5% moisture regain group. The advancing contact angles of the treated fibers decreased about 8°–16° whereas their receding contact angles decreased about 17°–27°. The interfacial shear strengths of the treated fibers as measured using microbond pull‐out tests were more than doubled when the moisture regain was 4.5 or 5.5%, whereas it increased by 58% when the moisture regain was 0.5%. In addition, no significant difference in single fiber tensile strength was observed among the plasma treated samples and the control sample. Therefore, we concluded that moisture regain promoted the plasma treatment effect in the improvement of the adhesion property of aramid fibers to epoxy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 242–247, 2006     

中温固化环氧/杂环芳纶（布）预浸料及其复合材料性能研究

试验研究了044B杂环芳纶布性能、3233/044B预浸料制备及其复合材料力学性能.结果表明,044B杂环芳纶布性能较好,3233/044B复合材料的常规性能和耐热性较好,夹层结构的滚筒剥离强度高,树脂具有韧性,适用于复合材料夹层结构.该预浸料已用于航空复合材料制件.     

空心玻璃微珠/环氧复合材料的制备及性能研究

制备了空心玻璃微珠/环氧复合材料。通过力学性能、固化收缩率、热性能等测试考察了空心玻璃微珠粒径、填充量、硅烷偶联剂处理对树脂及固化物性能的影响。结果表明,硅烷偶联剂改善了空心玻璃微珠与树脂基体的相容性。复合材料的力学性能随着空心微珠粒径减小而增大。随着空心微珠填充量的加大,固化物拉伸强度有所降低,冲击强度和弯曲强度在空心玻璃微珠质量分数为2%时达到最大值,比纯树脂分别提高了30%和34.2%,同时材料的固化收缩率和密度降低,玻璃化转变温度升高。     

环氧树脂基介电复合材料的制备和性能研究

以环氧树脂(EP)为基体树脂、经硅烷偶联剂改性后的压电陶瓷钛酸钡(BaTiO3)为增强填料,采用浇铸法制备了有机/无机介电复合材料。研究了填料用量对复合材料介电性能、力学性能和热性能的影响。实验结果表明,BaTiO3能显著提高材料的介电常数,当w(BaTiO3)=60%时,复合材料的介电常数为23.6,比纯EP的介电常数(4.0)提高了近6倍,而且复合材料的介电常数受频率影响较小,具有较好的频率稳定性;随着BaTiO3含量的增加,材料的弯曲强度和冲击强度都呈先增后减的趋势,最大弯曲强度和冲击强度分别为123.8 MPa和26.3 kJ/m2;材料的热稳定性研究表明,材料的起始热分解温度随着BaTiO3含量的增加而提高,材料的耐热性能得到改善。     

Interfacial strength measurements in poly(p-phenylene benzobisthiazole)/epoxy composites

A micromechanical study of the behaviour of poly(p-phenylene benzobisthiazole) ( )/epoxy interfaces is performed using two testing procedures, the droplet micropull-out test, and a version of the fragmentation test in which the stress and strain are continuously monitored by optical microscopy and video recording. Since very few interfacial strength data are currently available for /epoxy composites, it is the purpose of our study to generate such data for this system. The fragmentation phenomenon in /epoxy is found to be complex and more difficult to interpret than in brittle fibre composite systems, due to the fibrillation failure mode of the fibre. The interfacial shear strength value based on the fragmentation test is 17.3 MPa, approximately twice the value measured with the droplet micropull-out test.     

改性空心玻璃微珠/环氧树脂复合材料力学性能研究

采用偶联剂对玻璃微珠表面进行改性处理,借助超声波振动,使改性空心玻璃微珠在环氧树脂中均匀、稳定分散,增强了玻璃微珠与环氧树脂之间的相容并探讨了改性空心玻璃微珠对环氧树脂力学性能的影响。结果表明,复合材料中改性空心玻璃微珠添加质量分数为3%时,其拉伸强度达到最大值68.54 MPa,与空白样相比提高了20.3%;冲击强度达到最大值24.42 kJ/m2,比纯环氧树脂提高了166%;KIC(断裂韧性)达到最大值2.338 MPa/m2,是空白试样的2.27倍,增韧效果较为明显。     

玻璃鳞片含量对环氧胶强度和吸水性的影响

通过测试环氧胶粘剂剪切强度、经冷热循环水浴浸泡的试块的吸水性和密度变化,研究了玻璃鳞片含量对环氧胶粘涂层界面粘接强度、吸水性能的影响。研究结果表明,玻璃鳞片增加时,胶层的密度增加;经长时间浸泡后试样的密度均明显提高,含量为30%的试样增幅最大,但其体积几乎保持不变。分析试验结果后可知,胶层经浸泡后的体积变化率也应是评定其耐水性能的重要因素。     

纳米环氧树脂复合涂层耐冲蚀磨损性能研究

研究了固化剂低分子聚酰胺、有机蒙脱土和纳米Al2O3的用量对环氧树脂胶粘涂层拉伸剪切强度和耐冲蚀磨损性能的影响。试验表明,有机蒙脱土和纳米Al2O3能有效提高涂层拉伸剪切强度和耐冲蚀磨损性能,在最佳配方下,涂层的耐冲蚀磨损性能是Q235钢的10.83倍。     

聚硫橡胶对环氧树脂固化动力学及力学强度的影响

用红外光谱分析了在环氧树脂中加入聚硫橡胶的固化及增韧过程,通过差示扫描量热法研究了增韧体系的反应动力学,探讨了聚硫橡胶用量对固化产物力学强度的影响,并对试样断口形貌进行了扫描电镜观察。结果表明,聚硫橡胶的加入降低了环氧树脂的表观活化能而没有改变反应级数,使得固化反应的总放热量减少、放热过程更加平均。聚硫橡胶对环氧树脂的增韧效果明显,二者通过化学键结合,韧性撕裂的冲击断面形貌验证了这种活性增韧。当聚硫橡胶用量为30份(质量)时,环氧树脂固化物的冲击强度可达到未增韧者的896%。     

Study on wettability improvement and its uniformity of wool fabric treated by atmospheric pressure plasma jet

The influence of processing parameters on wettability improvement and its uniformity of wool fabric treated by atmospheric pressure plasma jet (APPJ) was explored. A woven wool fabric was treated by APPJ under various treatment conditions such as different treatment time, different oxygen flow rate, and different jet‐to‐substrate distance. The water absorption time of wool fabric was measured to determine wettability improvement. The diffusion photo of water droplet on wool fabric surface was taken by digital camera to reflect wettability uniformity. After APPJ treatment, SEM observation showed that the scales on the wool fiber surface directly facing plasma jet pores were destroyed than those on the other fiber surface. XPS analysis showed that the carbon concentration substantially decreased. The concentration of oxygen and nitrogen significantly increased and but the concentration of sulfur and silicon did not obviously changed. With the addition of oxygen gas, more polar groups such as hydroxyl and carboxyl produced on wool fiber surface. The water absorption time of wool fabric greatly reduced indicating wettability improvement. The diffusion of water droplet on wool fabric surface was also larger and more homogenous suggesting uniform plasma treatment. It was concluded that the wettability improvement and its uniformity of the treated wool fabric increased and then decreased with the increasing oxygen flow rate and jet‐to‐substrate distance, and increased with the increasing treatment time. Therefore to achieve reasonable wettability and its uniformity of the wool fabric treated by APPJ, plasma treatment conditions have to be carefully chosen. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011