纤维复合材料蜂窝夹层柱的极限强度

考虑纤维复合材料蜂窝夹层结构的承载特性,蜂窝夹层住的总体稳定性应计及蜂窝芯子的剪切变形,从而得出修正的欧拉公式.在面板和蜂窝芯子胶接性能很好时,试验值与理论值很符合.当胶接性能一般时,通过对胶层应力分析,应用莫尔强度理论,得出以胶层强度控制的总体稳定的极限强度计算公式,对于一般湿法成型的纤维复合材料蜂窝夹层住,计算结果与试验值很符合.     

实现废旧聚酯高值利用

<正>围绕我国废旧聚酯资源循环再生发展战略需求,废旧聚酯高效再生及纤维制备产业化集成技术项目实现了我国废旧聚酯纺织品高效回收与高值利用,大幅提升了聚酯再生纤维技术水平。该项目获2018年度国家科技进步二等奖。聚酯纺织品也就是我们熟知的"涤纶",是服装的主要原料,占纺织纤维的六成以上。这类纤维生产中消耗大量能源,且难以自然分解,如何高效回收和循环利用是全球性难题。相关资料显示,我国废旧纺织品累计存量已超1亿t,废旧聚酯高效再生及纤维制备产业     

废旧涤纶纺织品回收BHET聚合及再生切片纺丝性能研究

为实现废旧涤纶纺织品的产业化循环利用,在前期小试研究的基础上,以公斤级废旧涤纶纺织品为原料,通过乙二醇(EG)蒸气脱色、EG醇解、回收对苯二甲酸乙二醇酯(BHET)纯化及缩聚制得百克级再生聚对苯二甲酸乙二醇酯(PET)切片,并对再生PET切片进行模拟熔融纺丝,研究了回收BHET的纯度及色度、再生PET切片的结构及性能、再生PET初生纤维的性能。结果表明：回收BHET的纯度为98.69%、色度L值为99.46,其品质优于市售石油基BHET;由回收BHET聚合制备的再生PET的特性黏数为0.681 dL/g,端羧基含量为15 mol/t,色度L值为89.59、a值为-1.82、b值为2.99,各项指标均达到纤维级切片国家标准要求;制备的再生PET初生纤维的断裂强度为0.78 cN/dtex、断裂模量为0.42 cN/dtex、断裂伸长率为182.98%,与石油基PET初生纤维的断裂强度、断裂模量及断裂伸长率相当;本回收方法为实现废旧涤纶纺织品“纤维到纤维”的化学法循环利用提供了可行新途径。     

电磁窗用蜂窝夹层复合材料内部缺陷超声C扫描检测

对某型号复合材料夹层结构内力情况进行分析,进行理论计算,建立力学模型;使用patrannastran大型有限元软件建立复合材料蜂窝夹层结构有限元模型,模拟试验件受力特点计算出蜂窝夹层结构失效过程,建立了合理的数学模型;采用ASTM C393试验标准对复合材料蜂窝夹层结构试验件进行试验,获得某型号复合材料蜂窝夹层结构强度,并将试验结果与计算结果进行对比分析,得出蜂窝夹层结构的受力特点及验证模型的准确性。     

复合材料蜂窝夹层结构四点弯曲性能研究

对某型号复合材料夹层结构内力情况进行分析,进行理论计算,建立力学模型;使用patrannastran大型有限元软件建立复合材料蜂窝夹层结构有限元模型,模拟试验件受力特点计算出蜂窝夹层结构失效过程,建立了合理的数学模型;采用ASTM C393试验标准对复合材料蜂窝夹层结构试验件进行试验,获得某型号复合材料蜂窝夹层结构强度,并将试验结果与计算结果进行对比分析,得出蜂窝夹层结构的受力特点及验证模型的准确性。     

玻璃钢蜂窝夹层复合材料抗爆性能研究

介绍玻璃钢蜂窝夹层复合材料的结构与特点,研究了玻璃钢蜂窝夹层复合材料的动,静态力学性能,并根据材料测试结果研究了由其制作的浅埋抗爆结构的抗焊性能,分析了实验现象的结果。玻璃钢蜂窝夹层结构复合材料具有良好的动,静态力学性能,是制作浅埋抗爆结构的理想材料。     

再生聚酯及其纤维的结构性能研究

以废旧聚酯(PET)纺织品为原料,加入乙二醇(EG)使其醇解,经液相增黏制得再生PET切片,由熔融模拟纺丝制备了再生PET纤维,并对再生PET切片及再生纤维的结构和性能进行了测试表征。结果表明:废旧PET纺织品加入乙二醇进行醇解再增黏可制备的再生PET切片特性黏数([η])大于等于0.65dL/g;再生切片可纺性良好,所得纤维横、纵向截面均光滑、密实,无明显结构缺陷;当乙二醇和PET纺织品质量比为1∶8时,所得再生PET切片的[η]为0.713 dL/g,其纤维具有较好的结晶性能以及良好力学性能,纤维的断裂强度为3.58 cN/dtex。     

多孔纤维填充芳纶蜂窝夹层结构吸音隔音性能研究

为了提高芳纶蜂窝夹层复合材料的吸音降噪性能,在蜂窝夹芯中填充PET多孔纤维和PP纤维混合吸音材料,研究了蜂窝高度、多孔纤维填充量、蒙皮开微孔等对蜂窝夹层结构吸音系数(SAC)和传声损失(STL)的影响。结果表明:填充吸音棉、蒙皮开孔可有效改善复合材料夹层结构的吸音性能。在中高频段(0.8 kHz～2.5 kHz)内,当纤维材料在蜂窝夹层结构中的填充量为300 g/m~2时,SAC的峰值为0.84,提高了0.16,但纤维材料对结构STL的影响较小;蒙皮开微孔,有利于发挥微穿孔板的吸声作用和多孔纤维的吸音效果,SAC大幅度提高。     

碳纤维复合材料蜂窝夹层结构侧压强度理论计算

本文对碳纤维复合材料蜂窝夹层结构侧压强度进行了理论计算，试验值在理论计算范围内。理论计算公式可供碳纤维复合材料夹层结构产品设计时应用。     

复合材料蜂窝夹层板弹性常数测试及进展

本文介绍了软夹芯夹层板(例如铝金属蜂窝、复合材料蜂窝等)全部横向刚度弹性常数(弯曲刚度D_x、D_y,剪切刚度C_x、C_y,弯曲泊桑系数μ_x、μ_y和扭转刚度D_K)的系列梁式测试方案的理论基础、相互关系及发展过程。并通过实验,推荐介绍测定复合材料蜂窝夹层板主要参数弯曲和剪切刚度的最佳测试方案。     

Measurement,modeling, and variability of thermal conductivity for structural polymer composites

The through‐thickness thermal conductivity of polymer composite molds has a strong effect on out‐of‐autoclave manufacturing operations. Limited thermal conductivity and variability data is available for composites made from carbon fibers that are widely used in mold and aircraft construction. This article presents in‐plane and through‐thickness thermal conductivity data for structural carbon fiber polymer composites made from three types of reinforcements. Variability is quantified in all cases. Techniques for the predictive modeling of through‐thickness transverse thermal conductivity are assessed. Effects of variations in model geometry on conductivity are quantified. Conclusive observations on variability and recommendations on modeling techniques appropriate for the different reinforcements are made. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

石墨改性聚全氟乙丙烯导热中空纤维及其换热器的研制

塑料换热器在化工废水处理、酸碱盐循环设备等特殊领域具有重大应用价值,近年来得到了极大的发展。为提高换热器的整体换热效果,提高塑料换热器的最高使用温度,采用石墨作为填料,对聚全氟乙丙烯进行填充改性,以此制备出管壁薄、管径小且导热性能优良的复合材料导热中空纤维,将其加工后制作成换热器。重点探讨了石墨添加量及工艺加工条件对中空纤维物化性能的影响规律,并且通过冷热流体流程的变换及流量的改变研究其对自制的换热器总体换热性能的影响及规律。结果表明,利用石墨改性聚全氟乙丙烯复合导热材料制作的中空纤维换热器,价格低廉、体积小质量轻、单位体积换热系数较高且换热性能优异。     

Epoxy composites based on inexpensive char filler obtained from plastic waste and natural resources

In this study, plastic [polyethylene terephthalate (PET)] waste was recycled as raw material for the preparation of diglycidyl ether of bisphenol A‐type epoxy composite materials. The other inexpensive fillers used to prepare the composites were wood shavings char and pine cone char (PCC), obtained from natural resources. The thermogravimetric analysis showed that plastic waste char (PWC) and PCC can significantly improve the thermal stability of neat epoxy resin at temperatures above 300°C. The best thermal and electrical conductivity results were obtained with PWC. The residual weight of the composite with 30 wt% PWC was 69%. Surface hardness, Young's modulus, and tensile strength of the composites were higher than those with a pure epoxy polymer matrix. The composite morphology was characterized by X‐ray diffraction and scanning electron microscopy. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Conductivity of composite solid polymer electrolyte made of PEO-LiClO4-fiber

The conductivity of composite solid polymer electrolyte (SPE) made of different compositions of poly(ethylene oxide) (PEO), LiClO₄ and fiber was investigated in this study. Results obtained through alternating current (AC) impedance measurements demonstrated that the conductivity of the SPE was much improved by blending fiber into it. Moreover, increasing the composition of fiber added leads, thereby increasing the conductivity of the composite SPE. The average conductivity of the composite SPE was 10⁻⁴ S/cm at 25 °C. Performance in thermal properties was also investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) experiments. Although the mechanical strength of the composite SPE was not better than that of other materials as expected, the fiber added made it more stable.     

金属基有机硅树脂涂层复合材料的导热性能

以锌粉为导热填充剂对环氧有机硅树脂进行改性,考察了改性环氧有机硅树脂涂层干膜中锌粉含量对涂层导热系数的影响,分析了涂层厚度对碳钢基材导热性能的影响. 结果表明,环氧有机硅树脂涂层的导热系数约为0.19 W/(m?K),其耐温能力在200℃以上,可保证涂层在中低温烟气余热回收换热器表层长期工作而不发生任何热反应;添加锌粉可改善环氧改性有机硅涂层的导热性能,涂层干膜锌粉25wt%时,涂层材料导热系数达0.35 W/(m?K),较未添加锌粉时增大了84%. 复合材料的导热系数随涂层厚度增加而下降,无涂层的碳钢导热系数为47.59 W/(m?K),涂层厚度为200 ?m时,导热系数降至34.33 W/(m?K).     

废弃纤维再生混凝土孔结构及碳化性能分形特征研究

以水灰比、再生骨料取代率、废弃纤维长度和体积掺量为设计变量,利用压汞试验及快速碳化试验,探讨了废弃纤维再生混凝土的孔结构、碳化性能的分形特征以及两者之间的关系.结果表明:废弃纤维再生混凝土孔结构具有显著的分形特征,废弃纤维的加入可阻止结构中有害孔的形成,改善废弃纤维再生混凝土内部的孔结构;纤维的加入可以提高再生混凝土的碳化性能,最优体积掺量为0.12%,碳化边界轮廓线的分形维数越小,对应的碳化深度越大;废弃纤维再生混凝土的碳化深度与孔隙体积分形维数之间存在相关性,随着孔体积分形维数减小碳化深度增大,根据孔隙体积分形维数来评价不同设计变量的废弃纤维再生混凝土碳化深度是可行的.     

Thermophysical properties of carbon/graphite fibers and MOD-3 fiber-reinforced graphite

The flash method is extended to measure directly the thermal diffusivity of graphite/carbon fiber in unidirectionally fiber-reinforced composites and also in fiber bundles. The thermal diffusivity was measured using both composities and fiber bundles for Morganite II and Thornal 50 S graphite fiber and for composite samples containing PX 505 carbon fiber. In addition, the thermal diffusivity of Morganite II and Thornel 50 S graphite fiber was calculated from the effective thermal conductivity of composite samples measured by an absolute method. The thermal diffusivity of MOD-3 fiber-reinforced graphite was measured and the results were used to compute the thermal conductivity in the three orthogonal directions.     

甲基乙烯基硅橡胶导热复合材料的研究与制备

以甲基乙烯基硅橡胶为基体树脂,不同粒径碳化硅(SiC)和碳纤维(CF)复配作为填料,经开炼后模压硫化成型制得高导热复合材料。利用热流法导热系数测试仪(DRL-II)、扫描电子显微镜(SEM)对复合材料的导热性能、微观结构、力学性能进行了表征。结果表明：碳化硅和碳纤维能够均匀的分散在基体树脂中,不同粒径的碳化硅复配能使复合材料的导热性能进一步提高,导热系数达到1.28w/(m.k)。加入碳纤维不仅能使基体内部形成串联的导热网链,进一步提高基体树脂的导热性能,使复合材料的导热系数达到1.88w/(m.k),同时提高了复合材料的拉伸强度。     

Reduction of cycle time by addition of silicon carbide filler to syndiotactic polystyrene/glass fiber composites

Reducing cycle time in injection molding process is important because it can save operational cost and increase product yield. Cycle time can be categorized by six criteria, which are metering time, time for closing a mold, packing time, holding time, cooling time, and the time needed to open a mold and to eject the molded product. It was found that the metering time is crucial to predict the cycle time of glass fiber reinforced syndiotactic polystyrene (sPS/GF, 60/40 by weight). In many cases, however, cycle time could be reduced by saving cooling time. This study is motivated by the demand to reduce the cycle time of sPS/GF composite. Since the increase of thermal conductivity leads to the reduction of cooling time, silicon carbide (SiC) is employed to evaluate if it can increase the thermal conductivity of sPS/GF composite. When SiC is added to replace entire GF in sPS/GF composite, the mechanical property of the resulting sPS/SiC (60/40 by weight) composite was not satisfied even though its thermal conductivity was enhanced to about 62 %. Within tolerable ranges in mechanical properties, SiC was added to replace a half amount of existing GF filler. sPS/GF/SiC (60/20/20 by weight) composite achieved the enhancement of thermal conductivity from 0.230 to 0.308 W/m K (34 %) which resulted in the effective reduction of both cooling time and cycle time from 16 to 10 s and from 47 to 38 s, respectively. It should be noted that additional time saving was obtained by 3 s between 6 s in cooling and 9 s in overall cycle time. It can be interpreted by the fact that the increase of thermal conductivity also accelerated the heating rate of sPS/GF/SiC composite.     

Development of light-weight insulating clay products from the clay-sawdust-glass system

Employing a simple dry-pressing and sintering process, lightweight clay products with various physical, mechanical and thermal properties have been fabricated from mixtures of maplewood sawdust, clay and soda-lime glass grains prepared from recycled waste glass. Studies showed that thermal conductivity, compressive strength, and cold water absorption of the sintered sawdust-clay products are significantly modified by the addition of sawdust particles to the clay mixes. Studies also showed that portions of the clay particles can be replaced with soda-lime glass grains of similar sizes. These light-weight composite clay products have compressive strength in excess of 31 MN/m², thermal conductivity value in the range 0.21–0.39 W/m, °C and water saturation coefficient of about o.72. The fabricated clay products exhibit attractive characteristics as building materials and could contribute to energy conservation because of their high thermal insulation value.