CF表面处理对SLS用PA12/CF复合材料性能的影响

利用热空气处理法和浓硝酸处理法分别对碳纤维(CF)进行表面处理,然后与尼龙(PA)12粉末按量比3∶7通过机械混合法制备PA12/CF复合粉末材料。将复合粉末材料进行注塑成型,考察了热处理温度及浓硝酸处理时间对复合材料力学性能和热性能的影响。结果表明,浓硝酸处理时间为1 h处理效果最好,与未处理的CF复合材料相比,注塑样条拉伸强度提高23%,弯曲弹性模量提高133%,维卡软化点提高6.2℃;扫描电子显微镜分析表明,经过热处理后的CF在PA12基体中分散均匀,两者的界面相容性良好。     

PS/CF复合粉末激光选区烧结工艺研究

为提高聚苯乙烯粉末烧结件的强度,制备了聚苯乙烯/碳纤维(PS/CF)复合粉末,采用正交实验方法研究了不同工艺参数对PS/CF复合粉末SLS烧结件弯曲强度的影响,确定了最优工艺参数。结果表明,复合粉末试样的弯曲强度最高可达7.49 MPa,比纯PS粉提高2.88倍;弯曲强度随扫描速度和层厚的增大而减小,随预热温度的增加而增大;PS/CF复合粉末的最优工艺参数为扫描速度1 800 mm/s,预热温度85℃,层厚0.18 mm。     

激光原位铺放CF增强PEEK基复合材料工艺研究

通过激光原位铺放制备了CF增强PEEK基(CF/PEEK)复合材料,采用差示扫描量热法(DSC)与热重分析法(TGA)对CF/PEEK热性能进行了分析,利用扫描电子显微镜(SEM)表征CF/PEEK微观形貌,并研究了不同温度与铺放压力下CF/PEEK的力学性能。结果表明,激光原位铺放温度在400℃到420℃、铺放压力在220 N左右时,PEEK基体的流动性较好,CF/PEEK粘接牢固,成型的复合材料具有优异的力学性能。     

热处理工艺对增材制造PEEK/CGF力学性能影响

针对连续玻璃纤维(CGF)增强聚醚醚酮(PEEK)复合材料丝材在增材制造中因快速冷却造成材料结晶不充分、力学性能较低、层间结合能力差等问题,通过差示扫描量热(DSC)分析和力学性能测试,探究了热处理工艺参数对PEEK/CGF打印件力学性能的影响规律。结果表明,适当的热处理工艺能够提高PEEK/CGF材料的结晶度,进而提升成型件的综合力学性能。当保温温度在180～200℃,保温时间在50～60 min时,PEEK/CGF打印样件的力学性能最优,热处理后样件的弯曲强度为269.1 MPa,层间剪切强度为26.11 MPa,拉伸强度为332.71 MPa,较热处理前分别提高94.48%,97.95%与16.9%。     

尼龙12/OMMT纳米复合粉末的制备及性能

利用十八烷基三甲基溴化铵(OTAB)对蒙脱土(MMT)进行有机改性,并通过溶液插层法制备尼龙12/有机蒙脱土(PA12/OMMT)纳米复合粉末。利用X射线衍射、傅立叶变换红外光谱、扫描电子显微镜等手段对改性后的MMT及PA12/OMMT纳米复合粉末的结构和微观形貌进行表征,并将复合粉末热压成型制成标准件,测试其力学性能和热性能。结果表明,经过有机改性,MMT的层间距由1.24 nm增加到了2.13 nm,且改性后的MMT能均匀地分散在PA12基体中,PA12/OMMT纳米复合粉末的成型件在拉伸强度、弯曲强度、冲击强度和热性能方面都优于纯PA12粉末。PA12/OMMT纳米复合粉末为选择性激光烧结技术(SLS)提供了一种性能良好的粉末材料。     

PS/化学气相沉积CF选区激光烧结多指标正交试验参数的优化

针对选择性激光烧结(SLS)工艺中聚苯乙烯(PS)粉末烧结件精度不高且强度不能满足实际需求的问题,将经过化学气相沉积法处理的碳纤维(CF)粉末、PS粉末、分散剂和抗静电剂进行机械混合,制备了PS/气相沉积CF复合粉末。以Z向尺寸相对误差、致密度和弯曲强度为实验指标,先采用极差分析法进行单个指标的优化,再利用综合平衡法对多指标正交试验进行整体参数优化分析。结果表明:复合粉末粒度主要分布在30.63~142.00μm;对于PS粉末烧结件,化学气相沉积CF粉末比普通的CF粉末具有更好的改善尺寸精度、填充和增强的效果;烧结件的最佳工艺参数组合为:预热温度为80℃,激光功率为27 W,扫描速度为1 800 mm/s和扫描间距为0.30 mm。此时烧结件的Z向尺寸相对误差为5.47%,致密度为0.626 g/cm3,弯曲强度为10.68 MPa。相比于纯PS粉末烧结件,分别提高了24.55%,30.42%,136.28%。     

CF增强PEEK/Cu复合材料的制备与性能

采用模压法制备碳纤维(CF)增强聚醚醚酮(PEEK)/Cu复合材料,研究了CF等离子处理时间、CF用量和热处理工艺对PEEK/Cu/CF复合材料力学性能的影响。结果表明:随着未处理CF用量增加,PEEK/Cu/CF复合材料的力学性能逐渐下降;当CF等离子处理时间小于等于4 min时,PEEK/Cu/CF复合材料的拉伸强度和冲击强度随处理时间增加而提高;等离子处理4 min,随CF用量的增加,PEEK/Cu/CF复合材料的拉伸强度提高,但其冲击强度下降。与未处理的复合材料相比,热处理Ⅱ和Ⅲ这2种处理工艺的复合材料结晶度和熔点均提高,且热处理Ⅲ的提高幅度大于热处理Ⅱ的。     

选区激光烧结PS/AF复合粉末材料的初步实验研究

为了解决聚苯乙烯(PS)选区激光烧结(SLS)成型件质量较差的问题,使用不同工艺下的芳纶纤维(AF)作为增强改性材料制备了两种PS/AF复合粉末材料;在激光功率30 W,轮廓扫描速度2 200 mm/s等条件下,通过控制变量法分别研究了预热温度、分层厚度及填充扫描速度对两种PS/AF复合粉末材料SLS成型件精度及弯曲强度的影响规律。结果表明,PS/AF复合粉末材料SLS成型件的X、Y向尺寸精度不受工艺参数变化的影响;以聚合球磨AF为填料的PS/AF复合粉末材料成型件整体上的Z向成型精度较好,但其弯曲强度值低于以短切AF为填料的PS/AF复合粉末材料;在试验范围内,得到预热温度、分层厚度及填充扫描速度较优工艺参数范围为85～95℃,0. 20～0. 24 mm和1 400～1 800 mm/s。     

热处理对PEEK/MWCNTs复合材料性能影响

对聚醚醚酮(PEEK)/多壁碳纳米管(MWCNTs)复合材料进行热处理,研究热处理温度对PEEK/MWCNTs复合材料力学性能和热性能的影响。结果表明:热处理可明显提升复合材料力学性能,与未热处理相比,拉伸强度和弯曲强度分别提升了9.2%和18.6%。热处理可明显提高复合材料熔点和结晶度,250℃下热处理的复合材料熔点升到348.13℃,结晶度升到31.5%。同时热处理可明显提高PEEK/MWCNTs复合材料储能模量。最佳热处理温度为250℃,最佳热处理时间为2h。     

3D打印用PA6/PA12复合粉末的制备与性能

采用溶剂沉淀法制备了用于3D打印的尼龙(PA)6/PA12复合粉末,使用扫描电子显微镜和X射线衍射对复合粉末微观形貌与结构进行分析,使用差示扫描量热测试了复合粉末的熔融和结晶温度,同时测试了不同PA12含量下复合粉末的表观密度、粒径分布、熔体流动速率(MFR)和注射成型件的力学性能。结果表明,复合粉末颗粒近球形,其结晶度明显低于纯PA6粉末的结晶度,当PA12的质量分数增加至20%时,复合粉末的结晶度由纯PA6的66.48%降至42.66%;随着PA12含量的增加,复合粉末的表观密度减小,粒径大于150μm的粉末含量增加,当PA12质量分数为20%时,复合粉末的表观密度仍大于0.35g/cm~3,粒径在75～100μm的粉末含量虽有所减少,但仍在70%以上,且加入成核剂可明显减少大粒径粉末的含量;MFR及注射成型件的韧性随PA12含量增加而提高,但成型件强度和模量下降;PA12使复合粉末的烧结温度有明显的降低,烧结温度窗口增大,有利于选择性激光烧结。     

The improved interface performance between carbon fiber and poly(ether-ether-ketone) by sulfonated polyether sulfone (s-PSF) sizing agent with different sulfonation degree

The effects of sulfonated polyether sulfone (s-PSF) with different sulfonation degrees on the interfacial properties of carbon fiber (CF)/poly(ether-ether-ketone) (PEEK) composites were investigated systematically. The performance of the modified CF and the corresponding CF/PEEK composites and was tested and characterized. Test results show that the CF surface polarity increases, the surface contact angle decreases, and the surface free energy increases with the increase in the s-PSF sulfonation degree. Scanning electron microscopy analysis shows that the increase in the sulfonation degree of s-PSF is beneficial to improve the interface between CF and PEEK. This condition can be ascribed to the hydrogen bonding force between the s-PSF sulfonic acid group and the polar functional group on the surface of the modified CF and the compatibility between s-PSF and PEEK. In terms of physical properties, the thermal and mechanical properties of CF/PEEK composite are improved with the increase in s-PSF sulfonation degree. The interlaminar shear strength, flexural strength, and modulus of CF/PEEK composites increase by 60.16%, 30.27%, and 19.30%, respectively.     

Effect of surface modification of fly ash reinforced in polyetheretherketone composites

Fly ash reinforced polyetheretherketone (PEEK) composites were fabricated using compression molding technique. The fly ash surface was chemically modified using vinyltrimethoxy silane and 3‐aminopropyltriethoxy silane. The properties of treated fly ash PEEK composites were examined in terms of scanning electron microscopy, dynamic mechanical thermal analysis, differential scanning calorimetry, and thermo gravimetric analysis. The modified fly ash was observed to disperse more uniformly than the unmodified counterpart. The tensile strength and modulus also improved with treated fly ash filled PEEK composites. The increment of the dynamic modulus for the PEEK/treated fly ash composites is 32% at 250°C, indicating apparent improvement of high temperature mechanical properties. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers.     

Thermal Aging Properties of Graphite Fiber Reinforced Peek and Graphite Fiber Reinforced Bmi Composites

Graphite fiber reinforced poly(ether ether ketone) (PEEK) and graphite fiber reinforced bismaleimide (BMI) composite materials are two kinds of advanced fiber-reinforced polymer matrix composites with good thermal stability and excellent mechanical properties at high temperature. They are currently receiving considerable attention. the main limitation on their application is the lack of knowledge regarding their behaviors during extended use at high temperature. Thermal aging properties are the main parameters for new polymer matrix composites that will be used in advanced spacecraft structural components. From the results of thermal aging effects on the properties—including interlaminar shear strength, drop-weight impact strength, and impact energy—of graphite/PEEK and graphite/BMI composites, it is found that unidirectional graphite fiber reinforced composites retain higher strength compared to multidirectional, and that multidirectional graphite/PEEK composites keep higher property retentions than multidirectional graphite/BMI composites after thermal aging at 190°C. From scanning electron photomicrographs, it is also found that graphite/PEEK composites have better fiber/resin adhesion, intraply adhesion, and microcrack resistance compared to graphite/BMI composites after thermal aging.     

碳纤维增强聚醚醚酮的非等温结晶行为与力学性能

利用聚酰亚胺(PI)作为碳纤维(CF)界面改性剂,制备了界面改性碳纤维增强聚醚醚酮(MCF/PEEK)复合材料。采用差示扫描量热仪(DSC)讨论了CF及其界面改性对PEEK非等温结晶行为的影响机制与作用规律,并基于莫志深法研究了MCF/PEEK的非等温结晶动力学;借助DSC和小角X射线散射仪(SAXS)表征不同降温速率下PEEK基体的结晶结构,采用万能试验机评价了MCF/PEEK的力学性能。结果发现:CF对PEEK的结晶有较为明显的异相成核促进作用,经过PI界面改性之后成核作用有所下降,但结晶行为仍较纯PEEK更容易发生,整体结晶速率更快;随冷却速率的增大,基体结晶度、片晶厚度与长周期均减小,MCF/PEEK的拉伸强度与模量也显著减小,层间断裂韧性提高。     

Polyetheretherketone composites reinforced with surface modified mica

Mica fillers reinforced polyetheretherketone (PEEK) composites were fabricated using compression molding technique. To improve embedding of the mica within the PEEK matrix, the mica surface was chemically modified using vinyl trimethoxysilane (VTMO), at variable concentration (0–1.5 wt%). The performance characteristics and treated mica PEEK at mica loading of 20 wt% composites were examined in terms of scanning electron microscopy, dynamic mechanical thermal analysis, and modulated differential scanning calorimetry. The tensile strength and modulus improved to the tune of 81 and 44% with treated mica‐filled PEEK composites. Mechanical tests revealed improved properties of VTMO‐treated mica/PEEK composites, which confirmed improved interfacial adhesion with chemical treatment. The increment of the dynamic modulus for the treated mica PEEK composites was also noticed to 82% as compared with untreated counterpart, at elevated temperatures of 250°C, indicating apparent improvement of high‐temperature mechanical properties. POLYM. COMPOS., 31:2121–2128, 2010. © 2010 Society of Plastics Engineers     

Study on poly(ether ether ketone)/organically modified montmorillonite composites

Abstract

Novel poly(ether ether ketone) (PEEK)/organically modified montmorillonite (OMMT) composites containing 0–10 wt-% fractions of OMMT were prepared by melting blending method and the microstructure, thermal and mechanical properties were investigated using different characterisation techniques. X-ray diffraction and transmission electron microscopy showed that the OMMT was well dispersed with microscale in the PEEK matrix. Differential scanning calorimetry indicated that the glass transition temperature T _g and melt temperature T _m of PEEK/OMMT composites (POMCs) were hardly affected by the addition of OMMT, while the crystal temperature T _c decreased when the amount of OMMT excessed 1 wt-%. The data of thermogravimetric analysis exhibited that the thermal stability of POMCs in higher temperature region was better than that of pure PEEK. The results of mechanical properties test revealed that modulus and strength of POMCs increased with the content of OMMT, whereas the elongation at break and impact strength of POMCs decreased.     

Environmental effects on the water absorption and mechanical properties of carbon fiber reinforced PPS and PEEK composites. Part II

Research has been conducted to investigate the water absorption in carbon fiber reinforced poly(ether ether ketone) (PEEK/CF) and poly(phenylene sulfide) composites (PPS/CF). Effect of humidity and temperature on tensile, flexural, and impact strength of these composites were also studied. Results indicated that the water absorbed in PPS/CF and PEEK/CF are 0.059 %wt, 0.130 %wt, 0.138 %wt, and 0.153 %wt at 80°C. 75 %RH and 85 %RH, respectively. The diffusion process is a classical Fickian diffusion in the temperature range investigated. The activation energies of diffusion are 667 cal/g-mole (for PPS/CF) and 8934 cal/g-mole (for PEEK/CF) at 80°C and 75 %RH. The retention of mechanical properties of these composites is very good under hot-wet conditions. These composite materials can be served as high performance materials even in the hostile environment. PEEK/CF composites shows excellent mechanical properties retention even at 80°C, 75 %RH, and 85 %RH.     

Preparation of carbon fiber/Mg-doped nano-hydroxyapatite composites under low temperature by pressureless sintering

In order to protect carbon fibers (CF) from oxidation damage during sintering process, rod-like Mg-doped nano-hydroxyapatite (Mg-nHA) with an increased thermal decomposition temperature and reduced sintering temperature was synthesized by hydrothermal method. The synthesized bone-like Mg-nHA with similar composition and morphology to bone apatite was used as the matrix to prepare CF reinforced Mg-nHA composites (CF/Mg-nHA) at a low temperature of 700 °C by pressureless sintering. The increase of temperature slightly influenced the growth of Mg-nHA prepared by hydrothermal method from 160 °C to 200 °C. The Mg-nHA were short and rod-like in structure with a length of approximate 100 nm. When doping 1% magnesium, the decomposition temperature of Mg-nHA increased by 100 °C compared with that of nHA. This can protect CF from oxidation damage which is often encountered when sintering CF reinforced hydroxyapatite composites at high temperature and enhance reinforcing effects of CF. The bending strength of CF/Mg-nHA with 1 wt% CF was 8.51 MPa, which increased by 19.5% compared with Mg-nHA. Alternatively, the rod-like Mg-nHA was prepared on the surface of CF by electrochemical deposition and Mg-nHA coated CF was used to reinforce Mg-nHA, the coefficient of thermal expansion mismatch between CF and HA matrix could be mitigated. The compressive strength of Mg-nHA coated CF reinforced Mg-nHA (CF/Mg-nHA/Mg-nHA) composites with 0.5% CF sintered at 800 °C were 41.3 ± 1.56 MPa, which was attributed to the improved strengthening effect of CF and the good interface between CF and Mg-nHA matrix.