表面处理剂对NdFeB/环氧酚醛磁性复合材料性能影响研究

选用表面处理剂KH550对钕铁硼(NdFeB)进行表面处理,并用原位聚合法合成环氧酚醛NdFeB母料,进而制备出NdFeB/环氧酚醛树脂基磁性复合材料.同时研究了表面处理剂及其用量对磁性复合材料性能的影响.     

纳米硫酸钡/聚乙烯复合材料的制备及其加速老化性能

运用熔融共混方法制备了可X光显影的纳米硫酸钡(n-BaSO4)/聚乙烯(PE)复合材料。研究了铝酸酯偶联剂改性n-BaSO4(Al-n-BaSO4)在PE基体中的分散情况、复合材料的力学性能以及加速老化性能。运用XRD、FTIR、SEM及万能拉伸试验机等表征了产物的形貌、结构、力学性能及填料分布。结果表明:铝酸酯偶联剂与n-BaSO4表面基团发生了化学键合,在Al-n-BaSO4/PE体系中Al-n-BaSO4粒子的分散性较好,且平均粒径小于100nm。Al-n-BaSO4/PE复合材料的最大拉伸强度为11.87 MPa,弯曲强度为6.61 MPa,断裂伸长率为66.78%。Al-n-BaSO4/PE复合材料在模拟宫腔液中进行14周的加速老化实验后,复合材料的拉伸强度仅下降了5%~15%,预期Al-BaSO4/PE复合材料能在人体中使用10年以上。     

表面处理对玄武岩纤维增强酚醛树脂复合材料界面结合强度的影响

研究了不同浓度盐酸刻蚀处理纤维表面后再进行硅烷KH550、铝锆偶联剂处理对玄武岩纤维增强酚醛树脂基复合材料力学性能的影响,并用扫描电子显微镜观察复合材料表面的胶合情况.结果表明:随着盐酸浓度的提高,玄武岩纤维增强酚醛树脂(BF-PF)复合材料拉伸性能先降低后升高,在12 mol/L时达到最大值,弯曲性能和ILSS均降低,在6mol/L时为最大值.铝锆偶联剂处理的BF-PF复合材料的拉伸性能优于KH550处理的复合材料,但弯曲性能和ILSS低于KH550处理的复合材料.     

等离子体处理碳纤维/树脂复合材料

为了提高碳纤维/树脂复合材料的表面浸润性,采用等离子体直接对复合材料进行表面处理,通过接触角测试、拉伸试验、金相显微分析和红外光谱分析,探究了等离子体处理碳纤维/树脂复合材料的最佳处理工艺、处理前后碳纤维/树脂复合材料的力学性能和表面官能团的变化。结果显示:电流、气压和处理时间均对碳纤维/树脂复合材料表面浸润性有明显影响,当电流为1.0A、气压为1.0Pa、处理时间为10min时,表面浸润性最佳;处理后碳纤维/树脂复合材料的拉伸强度没有减小,反而提高了8%。红外光谱分析显示处理后碳纤维/树脂复合材料表面酯基链发生断裂,酯基数量降低,相应形成更多的酮基、羧基和醇羟基,表面极性增强,浸润性显著提高。研究解决了碳纤维/树脂复合材料表面呈惰性的问题,为其表面功能涂层制备奠定了基础。     

硅溶胶改性处理对碳纤维/环氧树脂复合材料拉伸性能的影响

用溶胶-凝胶法制备硅溶胶对碳纤维进行表面改性,观测了环氧树脂液滴在单向排列碳纤维集束表面的铺展过程;以环氧树脂为基体制备单向排列的碳纤维/环氧树脂复合材料,研究了硅溶胶改性处理碳纤维对其拉伸性能的影响。结果表明:碳纤维经过硅溶胶改性处理后,Si—o—Si,-NH₂等极性官能团的引入改善了环氧树脂对其的浸润性能,从而改善了碳纤维与环氧树脂间的界面粘结性能,使碳纤维/环氧树脂复合材料的横向拉伸强度显著改善,但纵向拉伸强度影响不大;与未经过表面处理的复合材料相比,经过硅溶胶改性处理的碳纤维/环氧树脂复合材料其横向拉伸强度提高了62.74%;与用硝酸处理的碳纤维制备的复合材料相比,用硝酸处理后再用硅溶胶处理的碳纤维所制备的复合材料,其横向拉伸强度提高了35.27%。     

TDI改性苎麻纤维增强PE复合材料的性能

以苎麻原麻、纱线、苎麻粗绳、苎麻布为原料,用甲苯-2,4-二异氰酸酯(TDI)进行接枝改性,然后制备出不同苎麻纤维与树脂PE的复合材料。采用扫描电镜(SEM)、电子万能拉伸试验机等分析测试手段对复合材料力学性能和断口进行了测试分析。结果表明:苎麻纤维经过TDI接枝改性后,其复合材料界面性能明显改善。接枝后原麻/PE复合材料复合拉伸性能略有下降,而苎麻绳和苎麻布/PE复合材料拉伸性能明显提高。     

改性炭纤维增强聚四氟乙烯复合材料的制备

研究了不同处理条件对复合材料拉伸、摩擦性能的影响,并对拉伸断口及磨损表面形貌进行了分析。结果表明,Ar等离子体处理、聚四氟乙烯乳液包覆的炭纤维能有效增大复合材料界面结合力并提高拉伸强度;当处理时间为9 min时,复合材料的拉伸强度为24.3 MPa,断裂伸长率为340%,磨损率为2.4×10-6mm3/N.m;与纯PTFE相比,拉伸强度和断裂伸长率分别提高了48%和100%,磨损率下降55.6%。     

木粉/PE复合材料与高速钢刀具摩擦特性的研究

目的 切削加工时木工刀具的摩擦磨损形式较为复杂,旨在研究高速钢与木粉/PE复合材料之间的摩擦特性.方法 通过木粉/PE复合材料与高速钢的摩擦试验,围绕木粉质量分数、往复频率、轴向载荷等因素,分析木粉/PE复合材料与高速钢摩擦因数的变化规律,以及试验后木粉/PE复合材料的表面形貌.结果 木粉/PE复合材料与高速钢刀具的摩擦因数随着木粉质量分数的增加呈现出先升高再降低的趋势,在木粉质量分数为50％时达到最大,摩擦特性为磨粒摩擦及粘着摩擦.结论 随着频率、载荷的升高,木粉质量分数较高的木粉/PE复合材料摩擦因数明显降低,高速钢刀具更适用于切削加工木粉质量分数较高的木粉/PE复合材料;摩擦试验后木粉/PE复合材料粗糙度显著降低,使用高速钢刀具切削加工木粉/PE复合材料,木粉质量分数为50％的材料试验后形貌较为平整,这为获得较好的表面切削质量提供了有力参考.     

CaCl1和多巴胺处理对芳纶纤维表面结构与性能的影响

采用氯化钙(CaCl2)乙醇溶液和多巴胺水溶液浸渍法对芳纶纤维表面进行改性处理,对改性后芳纶纤维表面的化学结构、微观形貌、表面粗糙度、单丝拉伸强度和芳纶纤维/环氧树脂复合材料的界面性能等进行了测试分析.结果表明,采用CaCl2乙醇溶液处理芳纶纤维后,芳纶纤维表面有刻蚀出的沟槽,表面粗糙度增大,芳纶纤维/环氧树脂复合材料的层间剪切强度明显提高,同时由于纤维结构受到破坏,单丝拉伸强度下降了11.12％;采用多巴胺水溶液处理时,芳纶纤维表面沉积了聚多巴胺涂层,表面粗糙度增大,芳纶纤维/环氧树脂复合材料的层间剪切强度进一步提高,纤维结构几乎不受影响,单丝拉伸强度降幅较小;采用CaCl2乙醇溶液和多巴胺水溶液先后处理芳纶纤维后,纤维表面的聚多巴胺涂层更致密,复合材料的层间剪切强度达到最大值,同时改性后的纤维具有一定的抗紫外性能,此方法改性效果最优.     

碳微球表面功能化对镁基复合材料的增强作用

纳米碳材料增强相与镁基体间的两相界面结合程度直接影响着复合材料性能的提高,而使用化学改性法对增强相进行表面功能化可以有效改善两相间的界面结合度.为了进一步研究表面功能化在提升复合材料性能上所起的作用,本研究选用CVD法和水热法制备的碳微球(CVD-CMSs和HT-CMSs)为增强相,一是使用一步改性法(即使用表面活性剂PVP直接处理)对增强相进行表面功能化处理,制备出CVD-CMSs/Mg和HT-CMSs/Mg,考察CMSs上接枝的含氧官能团对表面功能化处理的效果;二是使用两步改性法(即先使用化学沉积法将MgO颗粒裹附到碳球表面,再用PVP进行处理)对增强相HT-CMSs进行功能化处理,并制备出HT-CMSs@MgO/Mg,与HT-CMSs/Mg对比来考察HT-CMSs上负载MgO纳米颗粒的作用.采用傅里叶红外光谱仪、X射线衍射仪、光学显微镜、高分辨透射电子显微镜和拉伸性能测试仪等对复合材料样品的组织、界面结构和力学性能进行表征和分析.结果表明:CMSs上携带的含氧官能团对表面功能化处理的效果以及增强相的分散性都具有积极作用,且经PVP一步改性后制得的复合材料的增强相与基体间有MgO薄膜生成,改善了增强相与基体的相容性;经两步改性后,负载在HT-CMSs表面的MgO纳米颗粒使两相间的MgO膜增厚,进一步提升了两相间的界面结合度,起到有效连接增强相与基体界面的作用,并最终使复合材料的拉伸性能得到提高.     

PE-g-MAH/PP/高岭土复合材料的制备与性能

目的以PE,PP为原料,接枝马来酸酐(MAH)后,与高岭土经双螺杆挤出机熔融共混挤出,制备PE-g-MAH/PP/高岭土复合材料。方法采用电子万能试验机分析复合材料的拉伸性能;采用电子悬臂冲击实验机分析材料的缺口冲击强度;采用水平垂直燃烧仪测试分析复合材料的阻燃性;采用红外光谱仪分析复合材料的化学结构。结果含MAH质量分数为5%的PE与PP按质量比1∶1混合后,加入15%的高岭土,制备的PE-g-MAH/PP/高岭土复合材料拉伸强度、缺口冲击强度和断裂伸长率均为最佳,分别为10.925 MPa,40.6 k J/m2,89.5%;复合材料的阻燃性与高岭土加入量呈先快速增大后慢速降低趋势,加入量为15%时阻燃性最好;复合材料各组分间实现了化学键合。结论适量的高岭土提升了PE/PP复合材料的阻燃性,而MAH的加入改善了PE,PP和高岭土间的相容性。     

甲基丙烯酸甲酯接枝共聚制备极性聚乙烯

在水－甲苯介质中制备了聚乙烯－ｇ－甲基丙烯酸甲酯。用正交实验设计研究了引发剂,单体用量及反应时间等因素对接枝反应的影响。用裂解谱,扫描电镜,红外光谱等对接枝物进行表征。接枝聚乙烯对极性材料和如尼龙,铝箔,玻璃纤维等的界面亲和力有大幅度提高。     

Performance improvement of carbon fiber/polyethylene fiber hybrid composites

Carbon fiber/polyethylene (PE) fiber hybrid composites were fabricated by open leaky mold method. The positional effect of PE fiber was investigated concerning the mechanical performance improvement of carbon fiber/PE fiber hybrid composites. The influence of adhesion level of PE fiber on the hybrid properties was studied using oxygen plasma, -MPS, and -MPS-modified polybutadiene (PB/-MPS) as surface modifiers. In case of carbon fiber/vinylester composite, -MPS and PB/-MPS acted as the bridge to bond carbon fiber to vinylester resin through the chemical bonding. In case of PE fiber/vinylester composite, plasma treatment of PE fiber introduced the etching and micro-pitting rather than the functional group on fiber surface. Therefore, the plasma treated composite exhibited a large increase in flexural strength compared with untreated composite. In the case of carbon fiber/PE fiber hybrid composites, the mechanical properties of hybrid composite strongly depended on the reinforcing fiber position. When carbon fiber was at the outermost layer, the hybrid composite exhibited the highest flexural strength among other hybrid composites. This was attributed to the fact that the compressive and tensile stress had maximum magnitudes in the outermost layer. The surface treatment of PE fiber at outermost layer had a significant effect on the flexural strength of hybrid composite.     

The properties of aluminium coating on sintered NdFeB by DC magnetron sputtering

Pure aluminium coating was deposited on sintered NdFeB magnets by direct current (DC) magnetron sputtering to improve the corrosion resistance. The corrosion behaviour of sintered NdFeB coated with aluminium was characterized by potentiodynamic polarization measurement. The adhesive strength between the aluminium coating and the sintered NdFeB was characterised by vertical tensile test and high-low temperature shock test. The influence of the coating on the magnetic properties of the sintered NdFeB was also characterised. It was found that the aluminium coating can improve the corrosion resistance of the sintered NdFeB evidently. The aluminium coating was well adhesive with the substrate and did not deteriorate the magnetic properties of the sintered NdFeB magnets. These two characters may overcome the disadvantages of NiCuNi coating which is usually electroplated on NdFeB in industry.     

SML超分散剂的合成及在复合材料中的应用

介绍了超分散剂对粉体改性机理,并合成了SML超分散剂,考察了其改性超细CaSO4粉体后的活化指数,同时探讨了SML超分散剂对PE/超细能的影响,最后通过SEM观察了复合材料断面形貌.结果表明,SML超分散剂优于F-2分散剂.在其用量为3%时,活化指数可达97%,复合材料的拉伸强度、冲击强度、弯曲强度分别提高了28.7%、20.7%、4.9%.     

超高压杀菌处理对包装材料稳定性的影响

在超高压条件下对PET/AL/PE和PET/VMPET 2种塑料薄膜进行处理,测定不同压强及保压时间对材料拉伸强度、断裂伸长率、热封性能及阻隔性能的影响。结果表明:超高压对2种材料拉伸强度及断裂伸长率均未表现出显著影响,但对PET/VMPET/PE材料的热封强度影响显著;在500 MPa压强下保压时间对2种材料的透湿性能影响显著。     

Preparation and characterisation of PE films of carbon nanotube/polyaniline (PAN) composite mixture

ABSTRACT

Polyaniline (PAN) composites filled with nanotube were prepared by twin-screw extruder in order to study the influence of PE reinforcing effect on the mechanical behaviour of the nanotube/polyaniline (PAN) composites. The mechanical property tests of the composites with and without PE were performed. The tensile and flexural strength of nanotube/polyaniline (PAN) composites with polyethylene (PE) was improved. In conclusion, the addition of PE favoured the improvement of the higher interface strength and so had good effect on improving the tensile and flexural properties of the composites. The dielectric strength was slightly increased with the PE content increasing and then decreased gradually. The hybrid film with 2 wt.% of PE shows the dielectric strength of 199 MV/m, which is about 6% higher than that of nanotube/polyaniline (PAN) film (188 MV/m).     

Cure and mechanical properties of recycled NdFeB-natural rubber composites

Magnetic polymer composites containing recycled neodymium-iron-boron (NdFeB) powder and natural rubber (NR) were prepared by the two-roll mill technique. Their mechanical and cure properties were studied as a function of NdFeB loading from 0–120 phr. With increasing magnetic loading, the cure time of the NdFeB-NR composites were exponentially decreased because of the reduction of the polymer chain crosslink. The tensile strength of the NR compound, related to the cure characteristics, was reduced by 40% by the addition of 10 phr NdFeB fillers because of the inhibition of the stress-induced crystallization. However, the variation in loading from 30–90 phr has modest effects on the tensile strength as well as elongation at break and the hardness. Furthermore, recycled NdFeB-NR composites had higher modulus and lower percentage of swelling in this magnetic loading regime. Simple tests confirmed the distribution of magnetic stray field around pieces of NdFeB-NR composites.     

水菱镁石-Mg(OH)_2协同聚乙烯阻燃复合材料的性能与分解行为

以水菱镁石(HM)和Mg(OH)_2为阻燃剂,利用双螺杆挤出机制备了一系列HM-Mg(OH)_2协同聚乙烯(PE)阻燃复合材料。采用垂直燃烧仪、极限氧指数仪、锥形量热仪和拉伸性能测试仪分别测试了HMMg(OH)_2协同PE阻燃复合材料的阻燃性能和拉伸性能,采用热重分析仪研究了HM-Mg(OH)_2协同PE阻燃复合材料的热分解行为。结果表明,HM与Mg(OH)_2以适当比例复配作为阻燃剂能在更宽的燃烧温度范围内发生分解,起到更好的阻燃效果,在极限氧指数和拉伸强度不变的前提下,HM-Mg(OH)_2协同PE阻燃复合材料的成本大幅下降。两种阻燃剂协同可以减少复合材料点燃初期的无效甚至负面分解,保留了HM分解产物对PE基体高温下分解的抑制作用,同时还可以在燃烧区域表面形成较为稳定和不易破坏的鳞片状保护层,加之复合阻燃剂总体更高的总分解释放率,多种因素共同作用,使复合材料的阻燃效果提高。当HM和Mg(OH)_2以质量比1∶2协同且用量达到复合材料总质量的60wt%时,HM-Mg(OH)_2协同PE阻燃复合材料的极限氧指数为28%,垂直燃烧级别达到UL-94V-0级,拉伸强度达到28.8 MPa。