高性能纤维增强树脂基复合材料湿热老化研究进展

高性能纤维增强树脂基复合材料具有卓越的结构整体性及抗分层等特性,在诸多工业领域中具有广泛适用性。在其储藏及使用时,制件强度会不可避免地因湿热老化造成降解和退化。探讨和揭示高性能纤维增强树脂基复合材料在不同湿热老化环境下的力学响应,对其结构件的耐久性、安全服役性能和寿命预估具有至关重要的意义。综述了国内外高性能纤维增强树脂基复合材料湿热老化方面的研究进展,介绍了其吸湿机理以及在湿热环境下的老化机理。梳理了湿热老化环境对于高性能纤维增强树脂基复合材料力学性能的影响,寿命预测模型等。最后指出了高性能纤维增强树脂基复合材料老化研究存在的问题、面临的挑战,对未来研究发展方向提出了展望。     

基于孔隙控制的车身结构树脂传递模塑成型工艺设计

以典型车身结构B柱为研究对象,结合实验与仿真分析研究其树脂传递模塑(RTM)工艺的优化设计方法。研究了通过注射方式的优化控制树脂流动前沿,从而达到降低制件孔隙率和保证制件质量的目的。首先通过自制的变厚度渗透率测试模具获取所选用织物的渗透率,之后通过真空辅助RTM实验与对应模拟仿真进行对比分析来验证所采用仿真方法与渗透率数据的可靠性。最后结合充模周期与孔隙率控制理论对RTM工艺注射口分布及注射方式进行优化设计。结果表明,针对所选定车身结构,优化速率注射方式所获得的制件孔隙率最低,但充模周期较长,而基于双点注射的恒流量注射方式能较好地兼顾充模周期与制件孔隙率的要求。     

丙烯酸/环氧树脂自分层的研究

本文采用溶解匹配法测定聚合物的溶解度参数;通过FTIR-ATR、SEM、EMAX能谱等手段表征了合成有机硅丙烯酸树脂与环氧树脂的自分层情况;同时还研究了自分层清漆在环氧底漆上的附着力。结果表明树脂间溶解度参数差为1.7以上时,涂层可形成自分层,且自分层清漆涂层附着力达2 MPa以上。     

紫外荧光双马树脂基复合材料的制备及性能

紫外荧光树脂基复合材料可用于航空航天大型复合材料制件牺牲层的制备,减少装配中垫片的使用,并通过牺牲层的荧光显色避免切削时伤及本体铺层.采用热熔法制备了紫外荧光双马树脂及国产T700碳纤维机织物/紫外荧光双马树脂预浸料,采用热压罐法制备了国产T700/紫外荧光双马树脂复合材料.系统研究了未添加紫外荧光粉、添加1.8％含量...     

RTM工艺树脂注射温度优化

在RTM 工艺模拟及RTM 工艺专用树脂黏度特性研究的基础上, 提出充模时间与安全系数的乘积小于树脂低黏度平台时间的树脂注射温度优化标准和充模时间、树脂低黏度平台时间的计算方法, 制定了程序化流程并编制了软件, 使优化得以实施。在此基础上, 选取Q Y8911-Ⅳ双马树脂对所选制件进行模拟充模作为注射温度优化的实例, 确定了树脂低黏度平台时间的变化范围, 得到了不同条件下的优化注射温度。优化实例表明, 优化软件可实现对树脂注射温度的优化。      

基于芳纶pulp优化的碳纤维增强树脂基复合材料的抗损伤性能及残余抗压强度

针对树脂基复合材料树脂粘接层脆性大且存在结构缺陷,易发生剥离和分层等突出问题,提出以轻质高强的芳纶pulp(AP)作为增强剂,通过模压成型制得强化的碳纤维增强树脂基复合材料(CFRP),研究不同添加面密度对复合材料抗钻孔、钻孔-冲击二次损抗性能和损伤后的抗压强度的影响。结果表明,6 g/m2 AP使复合材料直接、钻孔以及钻孔-冲击后抗压强度分别增强37.3%、41.0%和41.8%。分析认为:AP改善了树脂脆性,消除层间富树脂区域,提升层间断裂韧性,抑制了裂纹生长;同时AP以纤维桥连形式贯穿于树脂层和碳纤维层,不仅改善了树脂与碳纤维粘接界面的缺陷,也构建准Z方向的纤维排布,避免裂纹向单层界面扩展而导致结构分层,从而实现结构强化。      

RTM成型复合材料T型接头工艺参数优化与力学性能实验研究

对树脂传递模塑(RTM)成型的复合材料T型接头进行了工艺参数优化、制备及力学性能实验研究。应用流动模拟软件,对RTM成型的复合材料T型接头进行了基体流动数值模拟,确定模具最佳注射方式和出胶口位置,并优化了影响树脂充模时间的工艺参数,显著提高了RTM接头的工艺性能。根据优化工艺参数结果,制备了RTM成型的复合材料T型接头试样,并进行了拉伸和压缩试验,分析了其破坏机制。根据拉伸和压缩试验现象和结果,发现RTM成型的复合材料T型接头拉伸破坏模式主要为富树脂三角区的树脂与纤维布界面分层,其拉伸破坏主要取决于树脂基体抗剥离分层的拉伸强度;压缩破坏模式为底板中央部位的弯曲分层与折断,其压缩破坏由接头底板中的纤维布抗拉强度决定;T型接头的压缩破坏强度高于拉伸破坏强度。     

真空导入工艺参数对复合材料孔隙含量的影响

以舰船构件为对象,通过玻璃纤维/乙烯基酯树脂复合材料的真空导入成型实验,研究了真空度、树脂温度参数对制件孔隙含量的影响规律。结果表明:真空度大小对孔隙率含量有显著影响,当真空度为80～90kPa时孔隙含量较低;低于20℃时,温度对孔隙含量有明显的影响,温度高于20℃时孔隙含量变化不大;沿树脂流动方向,试件孔隙含量由低到高变化;沿试件从上到下的厚度方向,孔隙含量也呈由低到高增加的趋势。     

填充纳米二氧化硅对感光树脂性能的影响

在紫外光可固化树脂中用在位分散法填充纳米二氧化硅(nm—SiO2），结果表明，nm—SiO2对紫外光可固化树脂的流变性影响较大；体系透光率较高，不沉降分层；可提高固化树脂的热分解温度和力学强度。     

基于黏弹性本构模型的热固性树脂基复合材料固化变形数值仿真模型

针对热固性树脂基复合材料热压罐成型工艺过程,采用广义Maxwell(麦克斯韦)黏弹性本构模型建立了残余应力和固化变形的三维模型。模型考虑了复合材料固化过程中的热-化学效应、材料的热胀冷缩效应、基体树脂黏弹性效应以及材料的各向异性。通过与文献中实验结果的比较,证明了所建立的模型具有较高的可靠性。对复合材料C型制件的固化过程进行了数值模拟和实验对比,比对结果表明该数值模型具有较高的准确性。     

UPR增强废旧PP研究

本文在研究废旧PP的加工热稳定行为的基础上,将UPR预固化处理后与废旧PP熔体共混,制备PP／UPR共混材料。研究结果表明,UPR在基体中以颗粒分散的形式存在,其加入可以大幅度提高体系的力学性能;此外,共混体系的力学性能改善应部分归于UPR诱导PP结晶。     

Characteristic impact resistance model analysis of cellulose nanofibril-filled polypropylene composites

Notched and unnotched Izod impact strength of cellulose nanofibers (CNFs) and microfibrillated cellulose (MFC)-filled impact modified polypropylene (PP) composites were measured and compared with microcrystalline cellulose (MCC)-filled composites. An Izod impact fracture initiation resistance theory was formulated and a characteristic impact resistance model was developed to evaluate the unique impact characteristics of cellulose nanofibril-filled PP composites. As filler loading increased CNF and MFC-filled composites showed higher characteristic impact resistance than MCC-filled ones. Among the cellulose fillers used in this study, CNF were found to be the most resistant of the three materials tested in terms of characteristic impact resistance. Even though impact resistance in not the only evaluation tool, characteristic impact resistance is an evaluation tool used to determine the material’s unique and hidden impact characteristics. The characteristic impact resistance model is useful for analysis of the impact behavior of any polymer composite material. It was also found that impact modified PP used in this study is more fracture resistant, but more crack sensitive, than conventional PP.     

非均质秸秆纤维复合材料保险杠蒙皮刚度分析

目的 研究非均质秸秆纤维复合材料保险杠蒙皮的刚度性能.方法 采用试验与模拟分析的方法,通过共混挤出与化学发泡注塑工艺制备微发泡秸秆纤维/聚丙烯(SF/PP)复合材料试样,通过试验测试非均质结构试样的力学性能与微观结构,通过有限元分析手段建立非均质微发泡秸秆纤维/PP复合材料结构分析模型,并分析非均质材料保险杠蒙皮的刚度...     

2012年PP及BOPP市场分析及展望

本文对2012年PP及BOPP行情做了简析，并进行了市场分析。指出了全年两次大的上涨和下跌所受外部因素和国内需求影响较大。对2013年PP及BOPP的形势做出了初步预测。     

动态固化PP/MAH-g-PP/EP共混物的等温结晶动力学

分别用Avrami方程和Hoffman结晶理论研究了马来酸酐接枝聚丙烯(MAH-g-PP)增容的动态固化聚丙烯(PP)/环氧树脂(EP)共混物中PP等温结晶动力学。实验结果表明,动态固化PP/MAH-g-PP/EP共混物中环氧颗粒可作为PP的成核剂,能显著促进PP的结晶。根据Avrami方程,动态固化PP/MAH-g-PP/EP共混物中PP的结晶速率常数K(T)明显大于纯PP的K(T)。依据Hoffman理论研究动态固化PP/MAH-g-PP/EP共混物结晶热动力学,动态固化PP/MAH-g-PP/EP共混物折叠链表面自由能(σe)明显小于PP折叠链表面自由能(σe)。     

Fourier transform infrared (FT-IR) imaging coupled with principal component analysis (PCA) for the study of photooxidation of polypropylene

Fourier transform infrared (FT-IR) imaging coupled with principal component analysis (PCA) is used to characterize the photooxidation of polypropylene (PP) and identify the photooxidative products at different oxidation times. PP slices were exposed to ultraviolet (UV) irradiation for times up to 60 hours and spatially resolved spectra were acquired with a transmission FT-IR imaging system in order to view the steric inhomogeneity of the photooxidation process of PP. The evolution of the oxidized products with irradiation time is shown through the application of PCA. Carboxylic acid is the major oxidized product in the initial period from 0 h to 8 h while ketone becomes the major product with the increase of irradiation time. Carboxylic anhydride is identified for the first time to our knowledge in oxidized PP after 16 h irradiation. Carboxylate ester is also observed in the oxidized PP after 32 h irradiation. Possible mechanisms forming these products have been discussed.     

Deficiencies of polypropylene in its use as a food-packaging material — a review

The outstanding chemical and physical qualities of polypropylene (PP) combined with an attractive price have made it one of the protagonists in the food-packaging industry. Like other polymers, however, PP tends to lose some of its constituents to the packed product, by migration, and when submitted to thermal, oxidative or radiation stresses PP starts to degrade. These processes are of concern when food is packed in the plastic, for they can cause PP to impart off-odour and off-taste to the packed product and in the worst case can give rise to toxicity of the food. This paper reviews the work that has been done on these processes and considers the recycling of PP for food-packaging use.     

环氧树脂包覆聚磷酸铵微胶囊的制备及其对聚丙烯的阻燃效果

为了探究环氧树脂包覆聚磷酸(EP@APP)微胶囊对聚丙烯(PP)的阻燃效果,首先,采用原位聚合法以EP为外壳包覆APP,制备了EP@APP微胶囊,并将其与PP进行复合,制备了EP@APP/PP复合材料。然后,测试了EP@APP微胶囊的溶解性,探讨了工艺参数对溶解性的影响;考察了EP@APP微胶囊的耐水性,并借助红外光谱分析了EP@APP微胶囊的表面官能团。最后,测试了PP复合材料的极限氧指数、拉伸强度和热重曲线,并分析了PP复合材料的热分解动力学。结果表明:当EP的加入量为APP的10wt%、固化剂加入量为EP加入量的15wt%时,采用先于40℃下维持1h、再于70℃下维持1h的阶跃升温方法可制备包覆完全的EP@APP微胶囊;该种微胶囊在水中溶解度低,且具有良好的耐水性。在PP中添加EP@APP微胶囊后,PP复合材料的极限氧指数为35.5%,达到V-0燃烧等级,燃烧后的残炭量增多,成炭效果明显优于直接添加APP的PP复合材料。与APP相比,EP@APP微胶囊对PP拉伸强度的破坏程度明显降低。EP@APP微胶囊的加入使PP复合材料的表观活化能由100.8kJ/mol提高到127.5kJ/mol,改变了PP复合材料的热降解氧化过程,且生成的残炭形成了稳定的保护炭层。研究结果表明EP@APP微胶囊可有效提高PP复合材料的阻燃性能。     

A comparative study of the effect of different rigid fillers on the fracture and failure behavior of polypropylene based composites

Polypropylene (PP) composites with 5 wt% of different rigid particles (Al₂O₃ nanoparticles, SiO₂ nanoparticles, Clay (Cloisite 20A) nanoparticles or CaCO₃ microparticles) were obtained by melt mixing. Composites with different CaCO₃ content were also prepared. The effect of fillers, filler content and addition of maleic anhydride grafted PP (MAPP) on the composites fracture and failure behavior was investigated. For PP/CaCO₃ composites, an increasing trend of stiffness with filler loading was found while a decreasing trend of strength, ductility and fracture toughness was observed. The addition of MAPP was beneficial and detrimental to strength and ductility, respectively mainly as a result of improved interfacial adhesion. For the composites with 5 wt% of CaCO₃ or Al₂O₃, no significant changes in tensile properties were found due to the presence of agglomerated particles. However, the PP/CaCO₃ composite exhibited the best tensile behavior: the highest ductility while keeping the strength and stiffness of neat PP. In general, the composites with SiO₂ or Clay, on the other hand, displayed worse tensile strength and ductility. These behaviors could be probably related to the filler ability as nucleating agent. In addition, although the incorporation of MAPP led to improved filler dispersion, it was damaging to the material fracture behavior for the composites with CaCO₃, Al₂O₃ or Clay, as a result of a higher interfacial adhesion, the retardant effect of MAPP on PP nucleation and the lower molecular weight of the PP/MAPP blend. The PP/MAPP/SiO₂ composite, on the other hand, showed slightly increased toughness respect to the composite without MAPP due to the beneficial concomitant effects of the presence of some amount of the β crystalline phase of PP and the better filler dispersion promoted by the coupling agent which favor multiple crazing. From modeling of strength, the effect of MAPP on filler dispersion and interfacial adhesion in the PP/CaCO₃ composites was confirmed.     

乙烯基笼型倍半硅氧烷/聚丙烯纳米复合材料热降解动力学

用热重分析(TGA)法研究了乙烯基笼型倍半硅氧烷(V-POSS)/聚丙烯纳米复合材料的热降解动力学.采用Kim-Park,Flynn-Wall-Ozswa和Friedman三种方法计算了共混物的降解反应活化能,结果说明,当V-POSS加入质量分数分别为4%、8%、12%和16%、升温速率为5℃/min时材料热降解起始温...