Nanoindentation Study on Mechanical Properties of Nano-SiO2/Dental Resin Composites

The micro/nano-scale indentation tests were performed to explore the performance of bisphenol-α-glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) dental resin composites. The effect of the filling content of nano-SiO2 particles on the mechanical properties of the dental composites was studied as well. The experimental results showed that the incorporation of the nano-SiO2 particles at low concentrations (up to 10 wt.%) can apparently increase the hardness and elastic modulus of the dental rein composites. The plasticity index indicates a best elastic recovery capability at a proper amount (4 wt.%) of the nanoparticles. Combined with the infrared spectrum, the mechanical enhancement mechanisms of the dental resin composites were analyzed.

Effect of volume fraction of ramie cloth on physical and mechanical properties of ramie cloth/UP resin composite

Ramie cloth/UP resin composite was formed at 0.2 MPa and cured at room temperature for 24 h and treated at 80℃for 2 h. The physical and mechanical properties of the composites with different volume fractions of ramie cloth were studied. The results show that, with the increase of the volume fraction of the ramie cloth, densities of the composites become greater and greater, though all lower than the theoretical values, the linear shrinkage during the formation decreases from 1.20% of the original UP resin to 0.18% of the composite with 30% of ramie cloth in volume, all the composites also absorb more water than UP resin casting, greater volume fraction of the fiber, more water will be absorbed, but the increase in water absorption becomes smaller and smaller with time. As regards some mechanical properties, the tensile strength, flexural strength, flexural modulus and impact strength are all improved when more ramie fiber is added. Compared with those of pure UP resin casting, the mechanical properties are increased by 93.93%, 76.20%, 190.18% and 227.26% respectively when the volume fraction of the ramie cloth in the composite is 30%. The differential scanning calorimetry results show that only one peak will appear for the sample without or with less ramie fiber while two peaks will appear when more ramie cloth is added.

Mechanical Properties of Phenolic-Resin Composites Reinforced with CF/BF Interlayer Hybrid Fibers

Phenolic-resin composites reinforced with carbon fiber（CF） and basalt fiber（BF） interlayer hybrid fibers plain fabric were fabricated.The tensile strength,compressive strength and interlaminar shear strength of the prepared composites were studied.The results indicated that hybrid fibers reinforced composites possessed the advantages of both CF and BF.When resin content was 35% by volume fraction,the comprehensive mechanical performance of BF/CF reinforced phenolic resin composites reached the optimal values with the warp and weft direction tensile strength,compressive strength and interlayer shear strength being 252 MPa and 487 MPa,105 MPa and 129 MPa,21 MPa and 20 MPa,respectively.The scanning electron microscope（SEM） observations showed that the BF/CF hybrid fibers reinforced composites had better interfacial adhesion.

Mechanical Properties of Glass Fiber/Unsaturated Polyester Resin Composite Water Collector

The water collector is operated in the humid and hot environment of the cooling tower all the year round.It also needs to carry part of the weight of water and silt.Therefore,it is particularly critical to optimize the material of the water collector and improve its mechanical properties.Polyester,a general term of polymer obtained from polyols and polyacids,is a kind of engineering plastics with excellent properties and wide applications.Glass fiber is a reinforced plastic reinforcement material,and the biggest characteristic of it is the high tensile strength and good heat resistance.In this paper,glass fiber reinforced polyester resin composite material is prepared,its tensile properties and bending properties are tested,and the performance of the imported material JK2020B is compared and analyzed.The results show that the elastic modulus along the fiber direction is relatively high,but the interlayer force in the direction of thickness and width is very small.This review provides a guidance for production process.

Mechanical and electrical properties of carbon nanotube reinforced epoxide resin composites

Carbon nanotubes(CNTs)/epoxide resin composites were prepared,the mechanical and electrical properties of the composites were investigated. The effects of concentration and dispersion state of CNTs on the tensile strength,tensile modulus and electrical resistance of the composites were studied. The results indicate that the CNTs can be dispersed well in the epoxide resin matrix by ultrasonic method,and the mechanical and electrical properties of epoxide resin matrix can be improved significantly. The tensile tests show that the tensile strength and tensile modulus are higher than those of epoxide resin if the content of CNTs is less than 1.75%(mass fraction). When the content of CNTs is 0.75%,the conditional best results are obtained,the tensile strength of the composite is the highest,increased by 18.3% and the tensile modulus is increased by 20.5% compared with the matrix. With the increase of CNTs,the electrical resistance of the composites decreases greatly,while the conductivity of the composite increases. The percolation threshold values of electrical characteristic transformation for this composite material were determined for the first time.

Effect of Hybridization on the Mechanical Properties of Pineapple Leaf Fiber/Kenaf Phenolic Hybrid Composites

In this study,pineapple leaf fiber(PALF),kenaf fiber(KF)and PALF/KF/phenolic(PF)composites were fabricated and their mechanical properties were investigated.The mechanical properties(tensile,flexural and impact)of the PALF/KF/PF hybrid composites were investigated and compared with PALF/KF composites.The 3P7K exhibited enhanced tensile strength(46.96 MPa)and modulus(6.84 GPa),flexural strength(84.21 MPa)and modulus(5.81 GPa),and impact strength(5.39 kJ/m2)when compared with the PALF/PF and KF/PF composites.Scanning electron microscopy(SEM)was used to observe the fracture surfaces of the tensile testing samples.The microstructure of the 7P3K hybrid composite showed good interfacial bonding and the addition of KF improved the interfacial strength.It has been concluded that the 3P7K ratio allowed obtaining materials with better mechanical properties(tensile,flexural and impact strengths)than PALF/PF and KF/PF composites.The results obtained in this study will be used for further comparative study of untreated hybrid composites with treated hybrid composites.

Mechanical properties of short carbon/glass fiber reinforced high mechanical performance epoxy resins

To research the relationship between epoxy and fiber inherent property and mechanical properties of composite,we prepared a series of composites using three kinds of high mechanical performance epoxy resins as matrices and reinforced by the same volume fraction(5%)of short carbon and glass fiber.Their mechanical properties were investigated from the perspective of chemical structure and volume shrinkage ratio of epoxy.We analyzed their tensile strength and modulus based on the mixing rule and Halpin-Tsai eq...

Preparation and Investigation of Mechanical and Physical Properties of Flax/Glass Fabric Reinforced Polymer Hybrid Composites

Synthetic reinforced composites affect the environment adversely and have become a global concern, causing increased natural composite demand for sustainability and cost effectiveness. Glass is a popular material that is highly consumed in reinforced composites for its superior mechanical strength. As opposed to that, flax obtained from flax stalks can be used as an alternative reinforcing material with synthetic fibers to minimize manmade fiber consumption. Hence, this research work addresses a few flax/glass-reinforced hybrid composites by using a thermoset polyester matrix. Here, six categories of samples are made, like neat flax, neat glass, and flax/glass fabric reinforced hybrid composite, followed by different stacking layer sequences and hand layout techniques during processing. Afterwards, the mechanical behavior, thermal stability, morphological behavior, and water absorption of hybrid samples were investigated. Among the developed samples, neat glass (NG) composite exhibits superior mechanical properties, while neat flax (NF) shows the lowest result. It is apparent that the mechanical properties and thermal stability of hybrid samples are in between NF and NG because, by adding glass with flax fabric, the strength of hybrid samples is increased. Moreover, it is noticeable that, due to multiple stacking layers of flax and glass, hybrid 3 and hybrid 4 show better strength than consecutive single stacking layers in hybrid 1 and hybrid 2. Among all hybrid composites, the H4 shows comparatively better mechanical and thermal properties due to having the glass layers on the outermost surface. In summary, this research work demonstrated the feasibility of flax fabric with glass fabric as a reinforced hybrid composite that can be used in automobile inner bodies, household furnishing, and home interior decoration.

Preparation and Investigation of Mechanical and Physical Properties of Flax/Glass Fabric Reinforced Polymer Hybrid Composites

Synthetic reinforced composites affect the environment adversely and have become a global concern, causing increased natural composite demand for sustainability and cost effectiveness. Glass is a popular material that is highly consumed in reinforced composites for its superior mechanical strength. As opposed to that, flax obtained from flax stalks can be used as an alternative reinforcing material with synthetic fibers to minimize manmade fiber consumption. Hence, this research work addresses a few flax/glass-reinforced hybrid composites by using a thermoset polyester matrix. Here, six categories of samples are made, like neat flax, neat glass, and flax/glass fabric reinforced hybrid composite, followed by different stacking layer sequences and hand layout techniques during processing. Afterwards, the mechanical behavior, thermal stability, morphological behavior, and water absorption of hybrid samples were investigated. Among the developed samples, neat glass (NG) composite exhibits superior mechanical properties, while neat flax (NF) shows the lowest result. It is apparent that the mechanical properties and thermal stability of hybrid samples are in between NF and NG because, by adding glass with flax fabric, the strength of hybrid samples is increased. Moreover, it is noticeable that, due to multiple stacking layers of flax and glass, hybrid 3 and hybrid 4 show better strength than consecutive single stacking layers in hybrid 1 and hybrid 2. Among all hybrid composites, the H4 shows comparatively better mechanical and thermal properties due to having the glass layers on the outermost surface. In summary, this research work demonstrated the feasibility of flax fabric with glass fabric as a reinforced hybrid composite that can be used in automobile inner bodies, household furnishing, and home interior decoration.

Effect of Natural Fiber Reinforced Polypropylene Composite Using Resin Impregnation

In this paper, we deals with mechanical performance of resin impregnation with natural fiber and fiber reinforced composites. The effect of the addition of a rein impregnation process on static strength of the injection molded composites was investigated by carrying out tensile and banding tests, followed by Scanning electron microscopy (SEM) observation of fiber surface and fracture surface of composites. The tensile strength of natural fiber and natural fiber reinforced composites with resin impregnation method increases with Polyvinyl alcohol (PVA) impregnation. In addition, Phenol resin impregnation recovers fiber tensile strength after alkali treatment. Resin impregnation causes decrease in contact surface area;however, it does not cause decrease in mechanical properties. Our results suggest that the using rein impregnation method has better effect on the mechanical properties of natural fiber reinforced Polypropylene (PP) composites.

The application of nanotechnology in the improvement of dental composite resins

In this paper, nanotechnology for the improvement of dental composite resins has been reviewed in the background of the existing shortcomings, focusing on the improvement for polymerization shrinkage, anti-bacterial properties and mechanical properties of composite resins. The results show that the use of nanotechnology and nano materials can be an effective method to improve the performance of dental composite resins in a various ways. At last, the paper also discusses the perspective about the dental composite resins.

Durability Testing of Composite Aerospace Materials Based on a New Polymer Carbon Fiber-Reinforced Epoxy Resin

In this study,the durability of a new polymer carbonfiber-reinforced epoxy resin used to produce composite material in the aerospacefield is investigated through analysis of the corrosion phenomena occurring at the microscopic scale,and the related infrared spectra and thermal properties.It is found that light and heat can con-tribute to the aging process.In particular,the longitudinal tensile strength displays a non-monotonic trend,i.e.,itfirst increases and then decreases over time.By contrast,the longitudinal compressive and inter-laminar shear strengths do not show significant changes.It is also shown that the inter-laminar shear strength of carbonfiber/epoxy resin composites with inter-laminar hybrid structure is better than that of pure carbonfiber materials.The related resistance to corrosion can be improved by more than 41%.

Evaluation of Sawdust and Rice Husks as Fillers for Phenolic Resin Based Wood-Polymer Composites

We produced Wood-Polymer Composites (WPCs) with phenolic resin (PR) filled with saw dust (SD) and rice husks (RH) in a PR:fillerratio of 60:40 wt.%. RH and SD were grinded and sieved into particles μm. The aim of this research work was to evaluate sawdust and rice husks as fillers for sustainable phenolic resin based WPCs. Therefore, we investigated the thermal stability of PR/RH and PR/SD WPCs then we studied and compared the tensile, flexural properties of PR/SD and PR/RH WPCs samples, as well as their dimensional stability after water absorption test. Furthermore, through ultraviolet light exposure, we evaluated the effects of photo-oxidation on the water stability and mechanical properties of PR/RH and PR/SD WPCs samples compared to unexposed ones. PR filled with SD presented better mechanical properties compared to PR/RH WPCs samples. However, PR/RH WPCs showed good mechanical properties, and better thermal resistance and better water repulsion capabilities compared to PR/SD WPCs samples. Although, long time UV exposure ended up lowering considerably the mechanical properties and water resistance of PR/SD and PR/RH WPCs, both RH and SD offer great added value as fillers for PR based WPCs;SD having better interactions with PR matrix compared to RH.

环氧基POSS/PAMAM杂合材料的制备及其性能

以3-缩水甘油基氧丙基三甲氧基硅烷(EPTMS)为原料,合成得到了八官能团缩水甘油醚-多面体低聚倍半硅氧烷(简称POSS-EP)。采用4代树型端氨基聚酰胺-胺(PAMAM)作为POSS-EP和双酚A型环氧树脂(DGEBA)共混物的固化剂,制备了5个环氧基POSS/PAMAM杂化材料。通过动态差示扫描量热仪(DSC),研究了环氧和PAMAM的固化反应动力学。通过DSC、热重分析(TGA)、拉力和冲击测试,对环氧基POSS/PAMAM杂化材料的热性能和力学性能进行了研究。结果表明,该环氧基POSS/PAMAM杂化材料具有优良的热性能和力学性能。

适用于HP-RTM板弹簧用环氧树脂固化工艺及验证

为更好解决树脂传递模塑成型(RTM)工艺存在的生产效率低、产品精度不高、孔隙率高等问题,高压树脂传递模塑成型(HP-RTM)工艺应运而生。其在应对大批量生产高性能热固性复合材料零件方面优势显著,可实现低成本、短周期(大批量)、高质量生产。为探索HP-RTM最适固化工艺参数,本文采用动态差示扫描量热法分析了环氧树脂不同升温速率下的DSC曲线,通过Kissinger方程和Crane方程计算出固化反应动力学参数,将所得参数带入固化反应动力学方程中,算出树脂最佳理论固化温度为110℃,达到完全固化时间为8 min。将环氧树脂与玻璃纤维按质量比1∶1.5的比例混合,通过HP-RTM工艺制备了复合材料板弹簧,工艺条件为:固化温度110℃,固化时间10 min。力学测试结果表明,试制的板弹簧各项力学性能均表现良好,经无损探伤检测后,产品内部无缺陷,可以满足应用需求。此为后续的复合材料板弹簧HP-RTM全工序试制平台及批量连续生产提供了有力技术支撑。

β-SiC纳米线增强POSS复合树脂的力学性能研究

目的:研究β-SiC纳米线的不同添加量对POSS复合树脂力学性能的影响。方法:将质量分数分别为0、0.5、1.0、1.5的β-SiC纳米线作为添加剂加入poss复合树脂。对各组试件的硬度、弹性模量、耐磨性等力学参数进行测试,对实验数据进行统计学分析。结果:统计学分析结果表明,0.5%组的硬度值、弹性模量值最高,划痕深度值最小,与其他各组比较,差异均有统计学意义(P<0.05)。结论:添加适量β-SiC纳米线可以显著增加POSS树脂的机械性能。

氨基POSS/环氧树脂有机无机杂化材料的动态力学性能

为了提高环氧树脂(EP)的综合性能,以含氨基官能团的笼型倍半硅氧烷(POSS)作为EP的改性剂,得到有机-无机POSS改性EP杂化树脂;然后以4,4′-二氨基二苯基砜(DDS)为固化剂对杂化树脂进行固化,得到有机-无机杂化材料。重点考察了POSS含量对杂化材料动态力学性能的影响。结果表明:不同杂化材料体系均呈单相结构,POSS在EP基体中分散较均匀,说明两者间相容性良好;随着POSS含量的不断增加,杂化材料体系的玻璃化转变温度(Tg)增大,与传统杂化材料不同的是损耗峰强度随POSS含量增加而降低,但损耗峰宽度几乎不变。

DOPO衍生物/八氨丙基POSS阻燃木塑复合材料的研究

先合成OA-POSS与DPA,然后将其引入到WF/PP木塑复合材料中,通过热压成型方法制备阻燃WF/PP木塑复合材料,进行热失重分析及阻燃性能、力学性能测试,探究了阻燃木塑复合材料的热稳定性能、燃烧性能和力学性能。结果表明:DOPO、DPA和OA-POSS的加入一定程度上提高了复合材料的初始热分解温度,降低了热分解速率,明显提高材料的热解残余物质量。DOPO,DPA和OA-POSS的加入能够显著提高复合材料的阻燃性能,复合材料的残炭量明显增加,最高增加228.05%。DOPO的加入使材料力学性能下降,而DPA和OA-POSS的加入一定程度上增强了复合材料的力学性能。

固化条件对苯并噁嗪树脂基材料力学性能的影响

苯并噁嗪树脂基复合材料具备耐高温,材料热稳定性高,固化后无组分溢出等特点,被广泛用于国产C919大型客机后机身后段等高温工作区域。采用热压罐固化工艺,评价了不同固化温度、固化压力、保温时间等固化工艺条件对苯并噁嗪树脂基复合材料力学性能的影响,以便选择最优的固化工艺条件,同时评价了该材料71℃的湿热老化性能。结果表明:固化温度对材料的压缩、层间剪切强度影响较小;随着固化压力的降低,材料的压缩强度和层间剪切强度略有降低;随着保温时间的延长,压缩强度略有增加,压缩模量略有下降,层间剪切强度变化较小;相比干态层间剪切强度,71℃湿热老化条件下的层间剪切强度下降幅度在7%以内,该材料在抗湿热老化性能方面表现优异。

不同腐蚀环境对含冲击损伤的碳纤维复合材料压缩性能的影响

碳纤维复合材料的性能很大程度上受使用环境的影响。本文研究了同一温度(70℃)下三种老化环境(蒸馏水、质量分数均为10%的硫酸溶液和氢氧化钠溶液)对T700碳纤维/环氧树脂基复合材料的压缩性能和含冲击损伤复合材料的压缩性能的影响;并研究分析了其质量变化、老化前后的表面形貌、傅里叶变换红外光谱(FTIR)及动态力学性能。结果表明:在蒸馏水和酸溶液中,质量变化率曲线符合FICK第二定律,质量变化率越大,材料的压缩性能、含冲击损伤材料的压缩性能和玻璃化转变温度下降越大,表面形貌破坏越严重;在碱溶液中,试样破坏严重,树脂也发生了化学反应,材料的性能和玻璃化转变温度不但受吸湿的影响,而且也受树脂化学反应的影响。研究结果对T700碳纤维/环氧树脂基复合材料在复杂环境下的使用和贮存具有重要的工程实际意义。