三维缝合结构阻尼复合材料制备与性能研究

通过选用柔性环氧树脂及不同的增强材料,制备三维缝合夹层结构复合材料,得到具备较佳阻尼性能和较高结构强度的复合材料。通过测定三维缝合结构阻尼复合材料的各项性能,得到三维缝合结构的最佳体系为结构层采用环氧树脂复合材料,阻尼层采用芳纶纤维布增强柔性环氧树脂,其阻尼比为3.33%,弯曲模量为14.3GPa,弯曲强度为290MPa,冲击韧性为338k J/m2。     

连续GF增强PP层合片材破坏形式及层间剪切强度研究

采用热压工艺制备连续玻璃纤维(GF)增强聚丙烯(PP)混编纱层合片材及GF呈0°和0°/90°铺放的连续GF增强PP层合片材。通过对3种GF增强PP层合片材进行力学性能测试,结果表明,3种GF增强PP层合片材的拉伸、弯曲强度随着层数的增加基本呈现先升高后降低的趋势。由于层合片材的层间剪切强度存在差异,因而使得3种层合片材产生不同的拉伸及弯曲破坏形式。通过插入PP薄层及PP-g-MAH薄层可改善层合片材的层间剪切性能,但插入PP薄层会降低层合片材的拉伸及弯曲性能,而插入PP-g-MAH薄层有助于提高层合片材的拉伸及弯曲性能。     

升温速率和胶层厚度对C/C复合材料弯曲性能的影响

采用炭布/酚醛树脂预浸料铺叠、固化、一次性炭化制备出密度为1.34 g/cm3的C/C复合材料,研究了制备工艺中升温速率和胶层厚度对其弯曲性能的影响。研究表明:升温速率和胶层厚度是C/C复合材料弯曲性能的重要影响因素。当升温速率为2℃/min时,未涂胶的C/C复合材料弯曲强度为43.70 MPa,比升温速率为5℃/min时提高了15.9%,而且所制备的C/C复合材料孔隙结构均匀;当胶层厚度为一层(0.2 mm)时,C/C复合材料的弯曲强度达48.17 MPa,比未涂胶时提高了12.2%,比胶层厚度为三层(0.6 mm)时提高了22.7%,且弯曲测试后裂纹较小,界面结合性较好,呈现塑性断裂。     

亚麻/PP复合材料的制备及其弯曲性能研究

将亚麻纤维作为增强体,与聚丙烯(PP)纤维进行混合,同时与PP长丝形成PP包覆亚麻的纱线结构,利用机织工艺织造成机织布作为复合板材的预制件,采用层合热压方法制备亚麻/PP复合材料。通过对板材弯曲性能进行测试,研究了制备工艺、纱线结构以及亚麻纤维含量(质量分数)等因素对复合材料弯曲性能的影响。研究结果表明,"三明治"铺层方法制备的板材较"混纤法"制备的板材体现出更优异的弯曲性能;与加捻纱相比,包覆纱结构板材表现出更优良的弯曲性能;以亚麻/PP包覆纱为增强体的复合材料,当亚麻纤维质量分数为46%时,其弯曲性能最优良。     

机织/针织混合铺层对复合材料力学性能的影响

为使纺织复合材料同时具有机织结构复合材料和针织结构复合材料的综合力学性能,通过混合铺层方式制备机织/针织混合结构复合材料。以芳纶机织平纹织物和针织罗纹织物为增强体,以环氧树脂为基体,调整复合材料中增强体的铺层顺序,利用真空辅助成型技术制备四层层压机织/针织混合结构复合材料。通过对复合材料拉伸性能、弯曲性能和冲击性能的测试,分析混合铺层和铺层顺序对芳纶环氧树脂复合材料力学性能的影响。结果表明,混合铺层和铺层顺序对芳纶环氧树脂复合材料的弯曲强度和冲击强度有较大影响,特别是对罗纹结构复合材料纬向弯曲强度和冲击强度的改善。当采用相同铺层方式,罗纹织物为受力面时,机织/针织混合结构复合材料具有较大弯曲强度和冲击强度。     

缝合泡沫夹层结构复合材料三点弯曲性能研究

采用改进锁式缝合方法,在真空辅助树脂传递模塑(VARTM)工艺基础上制备了缝合泡沫夹层结构复合材料,对其进行了三点弯曲测试,并对缝合参数对其弯曲性能的影响进行了实验研究。实验结果表明,在弯曲载荷作用下,其结构的失效大部分是由于芯材的剪切破坏,在缝合密度较大和纤维层较多的情况下,弯曲性能优异。采用缝合泡沫夹层结构可以提高复合材料的弯曲性能。     

熔融沉积成型木塑复合夹层板的弯曲性能

采用熔融沉积成型(FDM)制造方法,以木塑复合线材为原料,利用3D打印软件Ultimaker Cura的“填充结构”功能设计网格、直线、三角形等13种芯层结构(二维6种、立体7种),并将其与纸板粘接得到木塑复合夹层板。利用三点弯曲测试,研究不同夹层板的破坏失效形式与弯曲性能。结果表明:木塑夹层板的失效模式主要有弹性变形、面板起皱、芯子剪切和芯子压溃。在13种芯层结构中,立体的同心3D芯层结构夹层板弯曲性能最佳,弯曲模量和静曲强度分别为159.56 MPa和4.85 MPa,分别是网格芯层结构夹层板的5.4倍和2.3倍,具有较强的抗弯曲变形能力,适合于设计制造轻质高强度制品。     

亚麻增强热塑性树脂复合材料板材的研究与应用

以亚麻纤维为增强体,与聚丙烯(PP)纤维按一定比例进行混合,然后制备加捻纱及PP长丝包覆的包覆纱,并利用机织工艺织成二维机织布作为复合材料的预制铺层.采用层合热压方法制备PP/亚麻纤维复合材料板材.通过对板材弯曲性能的测试及分析,研究了制备工艺、纱线结构及亚麻纤维含量等因素对复合材料弯曲性能的影响.     

增强体织物组织结构对曲面复合材料力学性能的影响

为了探究曲面复合材料中增强体织物组织结构对其力学性能的影响,采用不同组织结构（平纹、斜纹、缎纹、无纬结构）的玄武岩织物,浸渍在环氧树脂与固化剂混合溶液中,在特制模具中加压复合成型制备了一系列曲面复合材料。采用3点弯曲试验法对曲面复合材料的弯曲强度和弯曲模量进行了测试,并且研究了曲面复合材料的冲击性能以及顶破强力及其破坏机理。结果表明,平纹增强体的玄武岩曲面复合材料弯曲性能最佳;组织结构为缎纹的玄武岩曲面复合材料冲击性能最佳,弯曲强度和平纹相近,在顶破强力上缎纹结构略低于斜纹结构。     

CFRP复合材料层间增韧结构优化

采用T700/6240碳纤维/环氧树脂预浸料和自制热塑性酚酞基聚醚酮(PEK-C)增韧膜,通过热压成型工艺制备不同层间增韧结构复合材料层合板,对其进行低速冲击、冲击后压缩及三点弯曲实验,并结合扫描电子显微镜(SEM)微观形貌表征及数学优化思想,确定最佳增韧结构。结果表明,在不同位置铺设12层增韧膜的四组试样中,中部增韧效果最佳,其冲击后压缩强度(CAI)比未增韧时提高42.39%。在层合板中部铺设8、16和23层增韧膜的试样,CAI和弯曲强度随增韧膜数量的增加分别呈现递增和递减趋势。通过弯曲试样SEM形貌表征发现,随增韧膜数量的增加,裂纹纵向扩展受到抑制,且由于环氧树脂与PEK-C的相容性较差,出现局部分层损伤。结合总增益和单层增益函数变化趋势,确定最佳增韧结构为层合板中部铺设11或12层增韧膜。     

碳纤维布/玻纤布增强聚氨酯复合材料的研究

以聚氨酯为基体树脂,分别以碳纤维布、玻璃纤维布和这两种纤维布交替铺叠作为增强材料,采用真空辅助灌注成型工艺制备了4种复合材料.考察了纤维布的铺层结构对复合材料的弯曲、拉伸和冲击性能的影响.结果显示,复合材料的拉伸模量和弯曲模量随碳纤维含量增加而增加,冲击强度则降低.分别采用TGA、DMA和SEM对复合材料的热性能、界面...     

Effect of carbon fabric type on the mechanical performance of 2D carbon/carbon composites

A stabilized PAN fabric was carbonized and graphitized from 800°C to 2500°C. Two-dimensional (2D) carbon/carbon composites were made using the stabilized PAN fabric, carbonized fabrics, and a resol-type phenol-formaldehyde resin. These composites were heat-treated from 600°C to 2500°C. The influence of different heat-treated fabrics and heat treatment on the fracture and flexural strength of these composites was also studied. The composite reinforced with higher heat-treated fabrics showed a lower weight loss than that with lower heat-treated fabrics. When the composites were graphitized at 2500°C, the loss was 49.7 wt% for the composite made with stabilized PAN fabric and 26 wt% for that with carbonized fabric at 2500°C. Those composites also have a higher density than composites produced by other methods. Composites made with stabilized PAN fabric exhibited a strong bonding in the fiber/matrix during pyrolysis. This composite showed catastrophic fracture and a smooth fracture surface with no fiber pullout. Composites made with higher carbonized fabrics exhibited a weak interface bonding. These composites showed a pseudo-plastic fracture pattern with fiber pullout during pyrolysis. Composites made with carbonized fabrics at 2000°C and 2500°C showed the highest flexural strength at the prolysis temperature of 1000°C. Composites made with carbonized fabric at 1300°C showed the highest flexural strength above 1500°C to 2500°C. The composite made with stabilized PAN fabric exhibited the lowest flexural strength during pyrolysis.     

连续玻纤增强聚丙烯混纤纱织物层压成型工艺研究

采用两种不同形式的混纤纱机织物为原料,利用层压成型的方法制备了连续玻璃纤维(GF)增强的聚丙烯(PP)板材。研究了层压温度、压力、保压时间和混纤纱机织物形式对层压板材的弯曲性能和层间剪切强度(ILSS)的影响。结果表明,当层压温度为230℃,层压压力为8.5 MPa,保压时间为30 min,降温过程冷却速度为0.5℃/min时,层压板材的力学性能最佳。弯曲强度和模量分别达到352.58 MPa、23.09 GPa,ILSS达到27.37 MPa。此时,纤维含量和空隙率分别为72.25%、2.03%。在最优工艺条件下制备的两种不同织物形式层压板材弯曲强度和弯曲模量以及ILSS:2/2斜纹织物平纹织物。两种织物层压板材的空隙率:2/2斜纹织物平纹织物。     

Some issues on impregnation in manufacturing of thermoplastic composites by using a double belt press

The manufacturing of thermoplastic composite intermediates by a continuously running double belt press (System of Held Comp., Germany) has become one of the most effective techniques for high quantity production. The process of combining thermoplastic materials and reinforcing fabrics during the manufacturing results in impregnation phenomena of the reinforcing layers distinct from one in resin transfer molding (RTM). Here, the work is focused on the clarification of the impregnation process that occurred in such a continuous manufacturing process. A composite intermediate of 50 wt% fibers consisting of E-glass fabrics and nylon 66 films (Zytel, DuPont) was produced at different processing conditions to exhibit the influence of the degree of impregnation on mechanical properties and damage patterns of thermoplastic composites. It can be proved that because of strong inhomogeneity in the fabric concerning the permeability of the yarns and the weaving structure, respectively, the time required to impregnate the fabrics is governed by transversal micro-flow into the fiber bundles rather than macro-infiltration of the polymer into the fabric structure. Imperfect impregnation resulted in specific damage pattern in the center of the compressed yarns after flexural loading. The results are to be applied to guide the optimization of the manufacturing process with respect to material selection and preselection of processing conditions.     

Pre-tensioning of fabrics in cement-based composites

This paper studies the effects induced by applying a pre-tension load during the production of fabric-cement composites. The flexural behavior as well as the bonding between the different fabrics and the cement matrix was examined, as a means for characterizing the processing parameters. Microstructure characteristics of the fabric-matrix interface as well as the viscous elasticity properties of the fabrics were also explored and correlated with the mechanical properties of the composite. It was found that pre-tensioning of fabrics and the time at which the tension is removed can significantly influence the performance of the composite depending on yarn properties, mainly the viscous-elastic properties, and fabric geometry.     

Effect of quasi‐carbonization processing parameters on the mechanical properties of quasi‐carbon/phenolic composites

In this work, quasi‐carbon fabrics were produced by quasi‐carbonization processes conducted at and below 1200°C. Stabilized polyacrylonitrile (PAN) fabrics and quasi‐carbon fabrics were used as reinforcements of phenolic composites with a 50 wt %/50 wt % ratio of the fabric to the phenolic resin. The effect of the quasi‐carbonization process on the flexural properties, interfacial strength, and dynamic mechanical properties of quasi‐carbon/phenolic composites was investigated in terms of the flexural strength and modulus, interlaminar shear strength, and storage modulus. The results were also compared with those of a stabilized PAN fabric/phenolic composite. The flexural, interlaminar, and dynamic mechanical results were quite consistent with one another. On the basis of all the results, the quasi‐static and dynamic mechanical properties of quasi‐carbon/phenolic composites increased with the applied external tension and heat‐treatment temperature increasing and with the heating rate decreasing for the quasi‐carbonization process. This study shows that control of the processing parameters strongly influences not only the mechanical properties of quasi‐carbon/phenolic composites but also the interlaminar shear strength between the fibers and the matrix resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Biopolishing of cotton fabrics with total cellulases of Trichoderma reesei and optimization using Taguchi methods

Biopolishing of cotton fabrics enhances appearance and handle of the fabrics without compromising on essential properties. Process of biopolishing is influenced by concentration of cellulases, temperature, pH, and duration of treatment, besides the activity levels of enzymes, method of mechanical agitations and construction features of fabrics. Optimization of process parameters, including mechanical agitations and fabric construction features, has been carried out using Taguchi methods followed by analysis of variance and confirmation tests. All the design parameters, used in the study, have predominant influence on weight loss, fabric strength after biopolishing while thickness, bursting strength, abrasion losses, and flexural rigidity of the fabrics were significantly influenced by the concentration of cellulases together with duration of treatment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

碳纤维/单分子环氧树脂基复合材料的研究

以流动性优异的单分子环氧树脂4,5-环氧环己烷-1,2-二甲酸二缩水甘油酯为基体树脂,甲基六氢邻苯二甲酸酐为固化剂,苄基二甲胺为促进剂,初步研究了其固化反应的化学流变特性,获得了基本的固化工艺。然后以T700S碳纤维平纹织物为增强材料,制备了2mm厚度的环氧/碳纤维复合材料层压板材。试验结果表明,通过稀释剂浸渍,复合材料中的CF质量分数可以达到70%以上。在完全无稀释剂时,CF的质量分数可以达到64%。复合材料的最高拉伸强度和弯曲强度分别为916MPa和1031MPa,其玻璃化转变温度为177℃。     

Effect of the atmospheric plasma treatment parameters on jute fabric: The effect on mechanical properties of jute fabric/polyester composites

The effect of atmospheric air plasma treatment of jute fabrics on the mechanical properties of jute fabric reinforced polyester composites was investigated. The jute fabrics were subjected to different plasma powers (60, 90, and 120 W) for the exposure times of 1, 3, and 6 min. The effects of plasma powers and exposure times on interlaminar shear strength, tensile strength, and flexural strength of polyester based composites were evaluated. The greatest ILSS increase was about 171% at plasma power of 120 W and exposure time of 6 min. It is inferred that atmospheric air plasma treatment improves the interfacial adhesion between the jute fiber and polyester. This result was also confirmed by scanning electron microscopy observations of the fractured surfaces of the composites. The greatest tensile strength and flexural strength values were determined at 120 W for 1 min and at 60 W for 3 min, respectively. Moreover, it can be said that atmospheric air plasma treatment of jute fibers at longer exposure times (6 min) made a detrimental effect on tensile and flexural properties of jute‐reinforced polyester composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fabrication of SiCf/SiC-mullite composite with improved pretreatment condition via precursor infiltration-sintering combined with infiltration-pyrolysis process

SiC fiber/ceramic matrix composite has potential applications in military and civil fields due to their excellent microwave absorption performances, light weight and oxidation resistance. In this work, the SiC_f/SiC-mullite composite with improved pretreatment condition was fabricated via precursor infiltration-sintering combined with infiltration-pyrolysis process for achieving excellent mechanical and microwave absorption performances. Results indicated that different dehydrations of matrix precursor influenced ultimate mechanical properties of the composites. At the same time, SiC derived from polycarbosilane had significantly improved several properties of the composite. The flexural strength and failure displacement reached 266 MPa and 0.46 mm, respectively. The high loss tangent was related with the interfacial polarization. In addition, a prominent reflection loss value of −45 dB was observed at 9 GHz. What's more, the maximum absorption bandwidth reached 2.9 GHz (from 8.2 to 11.1 GHz). The SiC_f/SiC-mullite composite with improved pretreatment condition is expected to be an excellent structural-functional material.