格构腹板式界面增强泡桐木夹芯复合材料梁的弯曲性能试验

复合材料及其夹层结构具有轻质高强、耐腐蚀、节能保温等特点,以玻璃纤维增强复合材料作为面层和格构腹板,以泡桐木为芯材,采用真空导入成型工艺,制备出格构腹板式界面增加泡桐木夹芯复合材料梁。在保持试件总尺寸不变条件下,对木梁、无格构木芯梁、格构木芯梁进行了平面、侧面四点受弯性能试验研究对比。得出如下结论:同一种构造试件平面受压时所受的极限承载力和刚度比侧面受压时所受的极限承载力和刚度高;无格构木芯梁、格构木芯梁试件所受的极限承载力和刚度比木梁试件所受的极限承载力和刚度有明显的提高;格构木芯梁试件所受的极限承载力和刚度比无格构木芯梁试件所受的极限承载力和刚度有一定的提高。     

湿热环境下泡桐木复合材料夹芯结构Ⅰ型界面剥离试验研究

采用人工加速老化的方法模拟湿热环境,通过泡桐木玻璃纤维增强复合材料夹芯结构的双悬臂梁拉伸剥离试验,研究湿热环境对玻璃纤维增强复合材料(GFRP)面板和泡桐木芯材的粘结性能的影响。试验结果表明,90 d湿热加速老化后泡桐木复合材料夹芯结构的能量释放率下降了32.3%,芯材泡桐木顺纹抗拉强度下降了11.6%,GFRP面板拉伸模量下降了11.0%。     

芯材增强对夹层圆柱壳屈曲性能的影响

应用有限元软件ANSYS,将表层和芯层的增强材料与芯材分开,采用8节点SOLID45实体单元,对增强型夹层圆柱壳建立物理模型,计算结构弹性屈曲的临界载荷。分析树脂量对提高点阵式及齿槽式增强圆柱壳轴向稳定性的作用,考察树脂材性、尺寸及分布等参数对屈曲载荷的影响,并将2种增强方式进行对比。结果显示:树脂柱以及树脂齿槽均可提高圆柱壳的抗屈曲性能,其中树脂材性对圆柱壳屈曲载荷的影响有限,而树脂柱和齿槽的疏密程度对圆柱壳的轴向承载能力有着明显的改进作用。总体上,齿槽式的增强效果比点阵式增强效果要好。     

泡桐木夹层结构材料的力学性能

选用泡桐木为原料,制备出夹层结构用泡桐木绿色夹芯材料,其木质纤维具有天然蜂窝形状,结构类似于目前航空航天领域常用的蜂窝芯材;泡桐木芯材除密度略高于Balsa轻木外,其他力学性能测试指标均优于轻木,同时在价格上占有绝对的优势。采用真空导入成型工艺,成功制备出轻质高强的泡桐木夹层复合材料,通过不同跨高比试件的三点与四点弯试验,研究其典型受力破坏形态与机制;利用经典夹层梁理论预估试件抗弯刚度和受弯极限承载力,理论值与实测值符合较好,并以此为基础,提出了基于强度的优化设计方法。     

格构增强型复合材料夹层结构的制备与受力性能

真空导入成型工艺是一种新型的适合大型/异型复合材料结构件成型的技术.选用H-60 PVC泡沫、四轴向玻璃纤维布以及乙烯基酯树脂,通过在泡沫芯材上、下表面开槽,同时沿芯材厚度方向剖开,采用真空导入成型工艺制备出在结构上具有创新构型的格构增强型复合材料夹层结构.研究结果表明,真空导入成型工艺充模速度快、成型效益高;格构增强型复合材料夹层结构的剪切、平压与抗弯性能均较传统夹层结构得以提高;其格构腹板可有效抑制泡沫芯材剪切裂纹的扩展,避免面板与芯材的剥离破坏;阐明了格构增强型复合材料夹层结构的受弯极限承载能力.     

EPON树脂在泡沫芯材拼接中的应用研究

本文通过测定EPON树脂在不同温度下的凝胶时间,从而提出EPON树脂在华南公司现场使用的环境控制要点,同时用泡沫芯材剪切试验考察EPON拼接后的泡沫芯性能,并对比未拼接的泡沫芯材夹层结构在室温干态、高温干态的性能数据,表明EPON树脂拼接后的泡沫芯材性能未下降,EPON树脂可以用于泡沫芯拼接。     

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。     

多孔固体芯材夹层FRP结构的工艺及性能评述

本文从制造工艺和材料性能等角度评述了FRP高性能夹层结构用芯材的特性,认为不同的多孔固体芯材在高性能夹层结构中是不可替代的,它们之间互为补充。     

耐压夹芯复合板制备工艺

介绍了一种耐压夹芯复合板的穿纱及树脂传递模塑(RTM)制备方法,选用橡胶为芯材,复合材料为蒙皮,通过RTM成型方法制备,研究了穿纱工艺及RTM工艺参数对制品的影响。结果表明,通过穿纱增强的RTM成型制品不仅表观质量良好,且具有优异的界面粘结性能,实现了承载吸声结构功能一体化设计,适用于深水压力环境。     

Nomex蜂窝夹层复合材料的成型工艺研究

针对Nomex蜂窝填充双马树脂基复合材料夹层结构在固化成型过程中易出现的蜂窝芯边缘塌陷问题进行研究。通过采用不同的成型工艺方法,以及对共固化工艺参数进行调整,研制出相应的双马来酰亚胺树脂基碳纤维/蜂窝夹层结构层板,并且对夹层结构的力学性能、内部质量以及平面拉伸性能进行测试。在此基础上分析了成型压力参数对夹层结构质量的影响。相关工艺试验表明蜂窝芯塌陷的原因主要是固化过程中蜂窝芯边缘的滑移引起的蜂窝局部失稳,通过采取分步成型、蜂窝先胶接后修型的方法能够有效地解决Nomex蜂窝夹层结构填充双马树脂基复合材料结构成型过程中的蜂窝芯塌陷问题。     

不同种类粘合树脂对轮胎带束层胶料性能的影响

研究不同种类粘合树脂对轮胎带束层胶料性能的影响。结果表明:新型粘合树脂MPRF,PRF和MPF游离单体含量低,在胶料加工过程中不产生刺激性气味,不冒烟,环保;与添加普通粘合树脂SRF的胶料相比,添加新型粘合树脂MPRF,PRF和MPF的胶料F_(L)和F_(max)较低,抗硫化返原性相对较好,门尼焦烧时间较长,胶料加工安全性提高;硫化胶的拉伸强度和拉断伸长率较高;钢丝帘线H抽出力在1000 N以上,完全能满足带束层对钢丝帘线粘合性能的要求。     

增黏树脂与弹性体SBS的相容性以及与热熔压敏胶性能的关系

热熔压敏胶(HMPSA)是一类不含溶剂的胶粘剂,在工业应用中占据很大的比重。工业上常用的增黏树脂有松香树脂、萜烯树脂和石油树脂三种。增黏树脂与热塑性弹性体SBS(苯乙烯/丁二烯/苯乙烯嵌段共聚物)的相容性存在一定的差异性,从工业角度重点研究和比较了增黏树脂的结构差异与性能之间的关系,并对其一般规律进行了探索。研究结果表明,当增黏树脂的软化点为100～110℃时,相应的HMPSA可获得较低的熔融黏度和较高的剥离强度,其初粘力为1～2cm;当增黏树脂的软化点为100℃时,剥离强度依次为含萜烯树脂HMPSA>含松香树脂HMPSA>含石油树脂HMPSA;当W(增黏树脂)= 210%时(相对于弹性体SBS而言),含石油树脂HMPSA的综合性能劣于含松香树脂(或含萜烯树脂)的HMPSA;当W(增黏树脂)≥210%时,HMPSA的熔融黏度低于10000mPa·s,但持粘力增强(即意味着内聚力增强)。     

高初粘力EPDM/金属界面胶粘剂的研究

在三元乙丙橡胶胶粘剂AE-2基础上,探索了提高EPDM/金属界面胶粘剂初粘力的途径,考察了增粘树脂HX,HY-209,GMA,TX和R11等对胶粘剂初粘力的影响,重点研究了增粘树脂HX用量对EPDM/金属界面粘接性能的影响,确定了高初粘力EPDM/金属界面胶粘剂AE-9配方组成。结果表明,加入增粘树脂HX后EPDM/金属界面胶粘剂初粘力效果最好。胶粘剂AE-9粘接性能优异,剥离强度达到4.0 MPa以上,粘接试样经80℃×180 d热空气老化试验后粘接强度没有降低,老化性能优异。     

Degradation of Rubber-to-Metal Bonds During Simulated Cathodic Delamination

Cathodic delamination of neoprene-to-steel adhesive bonds prepared using a proprietary vulcanizing adhesive and primer was investigated using Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Chlorinated rubber in the adhesive and primer was stable during immersion in NaOH solutions simulating the high pH conditions obtained at the bondline during cathodic delamination. However, methylene groups linking phenol moieties in phenolic resins in the primer were rapidly oxidized during immersion in NaOH solutions to form benzophenone linkages which were oxidized further to carboxylic acids and quinones. Chlorine produced by dehydrohalogenation of chlorinated rubber in the adhesive and primer during curing of the neoprene reacted with ZnO in the primer to form ZnCl₂ in the bondline. Failure of adhesive bonds between neoprene and steel during cathodic delamination is probably related to oxidation of the phenolic resins in the primer and to osmotic effects related to the high solubility of ZnCl₂.     

石油树脂对热熔胶、压敏胶粘接性能的影响

介绍了石油树脂的分类、增粘树脂的结构特点,国内外热熔胶、压敏胶用石油树脂发展,热熔胶对石油树脂的性能要求;论述了石油树脂与聚合物之间的相客性、石油树脂的软化点、熔融粘度等对热熔胶粘接性能的影响,展望了石油树脂的生产和发展方向.     

Relationship between Phenolic Adhesive Chemistry, Cure and Joint Performance. Part I. Effects of Base Resin Constitution and Hardener on Fracture Energy and Thermal Effects During Cure

In this study the relationships between the composition of phenol resorcinol-formaldehyde resins and paraformaldehyde concentration in the adhesive were explored, using DSC, IR, GPC, and solubility measurements. Differences of chemical composition between base resins and adhesives were compared to the fracture toughness of adhesive bonds.

The cure temperature and cure time effects upon fracture toughness were also investigated. Fracture toughness tests were performed with bonded hard maple tapered double-cantilever beam cleavage specimens.     

Relationship between Phenolic Adhesive Chemistry,Cure and Joint Performance. Part I. Effects of Base Resin Constitution and Hardener on Fracture Energy and Thermal Effects During Cure

In this study the relationships between the composition of phenol resorcinol-formaldehyde resins and paraformaldehyde concentration in the adhesive were explored, using DSC, IR, GPC, and solubility measurements. Differences of chemical composition between base resins and adhesives were compared to the fracture toughness of adhesive bonds.

The cure temperature and cure time effects upon fracture toughness were also investigated. Fracture toughness tests were performed with bonded hard maple tapered double-cantilever beam cleavage specimens.     

Reduction of formaldehyde emission from plywood

The aim of this work is to evaluate performances of tannin-based resins designed as adhesive in the plywood production. For this purpose, a part of phenol formaldehyde (PF) and melamine formaldehyde (MF) in the classic adhesive formulation was replaced by tannin. The physical properties of the formulated resins (rheological characterization, etc.) were measured. In order to analyze the mechanical performance of tannin-based resins, plywood panels were produced and the mechanical properties including tensile strength wood failure and three-point bending strength were investigated. The performance of these panels is comparable to those of plywood panels made by commercial PF and MF. The results showed that the plywood panels bonded with tannin–PF (PFT) and tannin–MF (MFT) resins exhibited better mechanical properties in comparison to the plywood panels made of commercials PF and MF. The introduction of small properties of tannin in PF and MF resins contribute to the improvement of the water performance of these adhesives. The formaldehyde emission levels obtained from panels bonded with tannin-based resins were lower than those obtained from panels bonded with control PF and MF. Although there are no actual reaction at all between PF, MF, and tannin, addition of tannin significantly improves the water resistance of PF and MF resins. This is a novel finding that manifests the possibility of replacing a convention PF and MF resins by tannin. Modified adhesive is one of the goals in the plywood production without changing any of their production conditions with improvement to their overall properties.     

室温固化耐600℃高温有机硅树脂耐热棉毡用胶黏剂

合成了苯梯树脂及耐热黏料树脂,二者以适当的比例配合再添加填料、促进剂、催干剂等来制备一种胶黏剂,并对胶黏剂与钛合金、隔热材料的胶接进行了探索性研究,该胶黏剂是可以室温固化的有机硅树脂胶黏剂,胶黏剂对钛合金与耐热棉毡均有较好的粘接性能,并且制得的胶黏剂在较高温度（650℃）有着较小的热失重,符合了钛合金与隔热材料实际粘接的需求。