超高分子量聚乙烯纤维表面改性的研究进展

超高分子量聚乙烯(UHMWPE)纤维具有诸多优异性能,因此被广泛应用于纤维增强复合材料(FRP)。但是由于UHMWPE纤维表面光滑且无极性基团,与树脂基体粘接性差,可通过纤维表面改性有效提高FRP的界面强度,进而提升材料性能。本文总结了近几年基于化学处理、等离子体处理、电晕放电和辐射引发表面接枝等方法对UHMWPE纤维表面改性的研究进展,并对改性方法的发展进行了展望。     

低温等离子体对聚偏氟乙烯表面处理的研究

本文通过ESR、电镜、接触角的测定、交联和剪切强度测定等手段研究了在不同等离子体条件下,聚偏氟乙烯(PVF_2)处理前后表面变化。结果表明,处理后PVF_2的粘接性能明显改善,剪切强度较未处理提高2倍左右。     

空气介质阻挡放电对超高分子量聚乙烯纤维表面性能及粘结力的影响研究

利用空气介质阻挡放电(DBD)等离子体对超高分子量聚乙烯(UHMWPE)纤维进行表面改性处理研究以提高纤维表面的润湿和粘结性能.分别研究了等离子体处理时间及电压对UHMWPE纤维拉伸断裂强力、接触角、表面形貌、表面化学成分和粘结性能等的影响规律.SEM分析结果表明,空气DBD等离子体处理后UHMWPE纤维表面出现垂直于纤维轴向分布的凹坑和裂纹,使得纤维表面粗糙度显著增加.XPS分析表明空气DBD处理后纤维表面碳元素含量显著下降;同时氧元素和氮元素的含量均较处理前增加,但氧元素含量增加的幅度显著高于氮元素.XPS分峰结果表明等离子体处理后UHMWPE纤维纤维表面C—O/C—N基团含量显著增加,同时出现了C O和O—C O这2种新的含氧官能团.同时,接触角及和与环氧树脂之间的界面剪切力(IFSS)测试结果表明DBD等离子体处理后UHMWPE纤维表面润湿性能和粘结力均产生显著提高,且随着等离子体处理时间或电压的增加,UHMWPE纤维的表面润湿性能和粘结力均呈现先上升后下降的趋势.空气DBD等离子体处理对UHMWPE纤维的力学性能影响较小,当处理电压低于200 V,处理时间小于100 s,纤维强力下降比率小于5.2%.     

聚(对亚苯基-1,3,4-噁二唑)纤维表面氟化处理研究

采用氟气(F2)对聚(对亚苯基-1,3,4-噁二唑)(p-POD)纤维表面进行直接氟化处理.衰减全反射红外光谱(ATR-FTIR)和表面电子能谱(XPS)的结果显示,通过直接氟化处理,p-POD纤维较易与F2发生反应,表面大分子链上引入了大量C—F键,表面氟元素含量高达28.2%,且F原子以—CF/C O、—CFH及—CF2形式存在,表明在表面氟化过程中,既有取代反应,也有加成反应.热失重(TGA)结果表明氟化前后p-POD纤维的耐高温性能没有受到影响,X射线衍射图谱(XRD)表明氟化后纤维的聚集态有序性略微增加.氟化前后纤维的断裂强度基本无变化,在体积分数为20%的硫酸溶液中的人工加速酸老化条件下,氟化后纤维在老化120 h后的断裂强力保留率在80%以上,相比氟化前的纤维提高了约90%,即耐酸性得到明显改善.推测表面氟化处理改善p-POD纤维耐酸性的机理是氟化后p-POD纤维表面N元素含量降低,抑制了溶剂化过程;纤维表面致密程度得到提高以及F原子与酸液形成氢键,从而阻止噁二唑环的质子化,延缓了老化进程.     

提高聚氨酯表面硅橡胶涂层粘接性研究

利用表面处理并借助硅烷偶联剂大幅提高了聚氨酯/硅橡胶(PU/SR)的界面粘接性.利用红外光谱、水接触角以及表面元素分析对PU表面处理效果及偶联剂的反应效果进行检测,利用扫描电镜对材料的表面形貌及界面情况进行观察.并对不同方法得到的PU/SR界面进行剪切和振动疲劳测试以考察其粘接效果并进行比较.结果表明,经过硫酸短时处理过的PU表面生成大量羟基,使得亲水性提高,并大大增强了端异氰酸酯基硅烷偶联剂与PU的接枝反应效果.当室温缩合固化的硅橡胶预聚体涂覆到其表面后,以化学键联接在PU表面的硅烷偶联剂又可以与硅橡胶一起缩合,从而有效的提高了PU/SR的界面粘接性.     

液态氧化法处理超高分子量聚乙烯纤维

用液态氧化法对超高分子量聚乙烯纤维进行了表面处理,研究了处理介质、处理时间对超高分子量聚乙烯／环氧复合材料层间剪切强度的影响,用扫描电子显微镜、ＸＰＳ表面元素分析、毛细浸润法测接触角等方法探讨了纤维表面性能处理前后的变化,以及纤维与树脂的界面结合情况。     

新型油面粘接剂Epasol FV/ZIS939

由西德 ZIS’Halle与VEB-Asol公司研制出来的Epasol FV/ZIS939粘合剂,是一种改性环氧基冷固性双组分粘合剂。由于其特殊的改性组成对于粘合表面污染,尤其是油质污染不敏感,它能将原有的油膜加以溶解和吸收,将操作表面充分浸润和活化。该胶液甚至对涂有石腊油、机油GL-125,及硅油M4-500浓油质涂脂的工件都有良好粘接能力(常温固化24小时后剪切强度为 270kg/cm~2左右),且对油膜厚度至今尚未发现     

直接氟化表面改性技术研究进展

直接氟化是直接用氟气作为氟化试剂对高聚物进行表面改性的新方法。其在聚合表面形成纳米级的氟化层,使得聚合物在其本体力学性能不受影响的情况下阻隔性、表面可粘接性等性能得到明显提高,并得到实际应用。同时直接氟化还可用于对碳纳米管、石墨以及分离膜等进行表面氟化改性,可提高其在溶剂中的分散性,电性能和选择分离性。该方法具备成本低,不需要催化剂,改性效果显著和工艺简单等优点。本文主要对直接氟化改性技术的发展、应用、直接氟化基本原理以及相关研究进展进行了综述。     

界面水分子扩散对超高分子量聚乙烯摩擦学性能影响的反应分子动力学模拟研究

采用基于反应力场(ReaxFF)的分子动力学模拟方法,研究了摩擦界面水分子向超高分子量聚乙烯(UHMWPE)基体扩散和渗透的基本过程.分子模拟结果表明：摩擦过程中,水分子稳定吸附在Fe板表面,并与聚乙烯链形成分子内摩擦,使聚乙烯分子产生剪切变形.当Fe板表面存在纳尺度外凸结构时,其在UHMWPE表面的耕犁作用更为显著,使摩擦界面的内摩擦力显著增加.当摩擦速度增加时,摩擦界面原子温度显著升高.在水润滑条件下,界面水分子逐渐扩散到UHMWPE基体中,引起相邻聚乙烯链之间的原子距离增加,这导致聚乙烯链之间的相互作用强度降低.此外,摩擦界面处还伴随着水分子中氢氧键断裂,并引起相应原子的电荷跃变.此时,水氧原子与Fe原子形成Fe―O化合物,且具有与Fe₂O₃相似的晶体结构.水分子扩散进入UHMWPE内时,还引起其周围聚乙烯分子的电荷发生改变,造成UHMWPE表层原子电荷分布不均匀.     

ZnO纳米棒改性超高分子量聚乙烯纤维及其性能研究

采用低温水热法在超高分子量聚乙烯(UHMWPE)纤维表面成功制备了致密均匀的ZnO纳米棒阵列,利用纳米棒阵列与树脂形成啮合结构,有效增强了纤维和树脂之间的界面结合强度.采用扫描电镜(SEM)、示差扫描量热法(DSC)、热重分析(TGA)、X射线衍射(XRD)等手段对纤维改性前后结构与性能变化进行了分析,并通过单丝拔出实验表征了其与环氧树脂间的界面剪切强度(IFSS);探索了反应时间、前驱液浓度对界面性能的影响.研究结果表明这种改性方法对纤维的本征性能几乎无影响,改性后纤维增重仅5%,而与树脂复合后界面剪切强度提升58%,单丝拨出时破坏发生在纳米棒阵列与纤维之间.进一步,利用该方法对UHMWPE织物进行改性,发现使用单宁酸可提高纳米棒阵列与纤维之间的结合力,使得到的UHMWPE@ZnO和UHMWPE@TA-ZnO织物的防穿刺能力分别提升20%和42%.     

Modification of ultra‐high‐molecular weight polyethylene by various fluorinating routes

Chemical–physical properties of ultra‐high‐molecular weight polyethylene (UHMWPE) treated by direct fluorination, direct fluorination accompanied with UV irradiation, by XeF₂ and by TbF₄, were tested by FTIR spectroscopy, visible spectroscopy, 19F and 13C NMR, scanning electron microscopy, XRD, and EPR. Surface energy measurements were carried out. The direct fluorination of UHMWPE is a diffusion‐controlled process, but treatment with XeF₂ is a kinetically controlled one. Direct fluorination and direct fluorination accompanied with UV irradiation results mainly in a formation of ? CF₂? groups. On the contrary, ? CHF? groups are prevailing in UHMWPE treated with XeF₂ and TbF₄. Surface texture of UHMWPE treated with XeF₂ and with F₂ is quite different. Direct fluorination results in a higher polarity of the polymer surface when compared with treatment with XeF₂. For the case of direct fluorination, both long‐lived peroxy and fluoroalkylradicals are formed. For the case of treatment with XeF₂, only fluoroalkylradicals were detected. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49:3559–3573, 2011     

Interfacial behavior between atmospheric-plasma-fluorinated carbon fibers and poly(vinylidene fluoride)

Atmospheric-plasma fluorination was used to introduce fluorine functionalities onto the surface of carbon fibers without affecting their bulk properties. The interfacial adhesion between atmospheric-plasma-fluorinated carbon fibers and poly(vinylidene fluoride) (PVDF) was studied by means of direct wetting measurements and single fiber pullout tests. Measured contact angles of PVDF melt droplets on modified carbon fibers show that short exposure times of carbon fibers to atmospheric-plasma fluorination (corresponding to a degree of surface fluorination of F/C = 0.01 (1.1%)) leads to improved wettability of the fibers by PVDF melts. The apparent interfacial shear strength as a measure of practical adhesion, determined by the single-fiber pullout test, increases by 65% under optimal treatment conditions. The improved practical adhesion is not due to the formation of transcrystalline regions around the fibers or a change of the bulk matrix crystallinity or to an increased surface roughness; it seems to be due to the compatibilization of the interface caused of the atmospheric-plasma fluorination of the carbon fibers.     

CMC系列高分子表面活性剂与原油超低界面张力形成机理的研究

采用动态激光光散射及环境扫描电镜研究了羧甲基纤维素系列高分子表面活性剂与大庆原油形成超低界面张力的机理.结果表明,CMC系列高分子表面活性剂具有与低分子量表面活性剂相比拟的表/界面活性,其水溶液的表面张力可达2835mN/m,界面张力达到10^-110mN/m.碱的加入可显著降低高分子表面活性剂与原油的界面张力,在适当条件下界面张力达到超低值(10^-3mN/m),可望作为三次采油的驱油剂.等效烷烃模型研究表明,用碱与原油酸性组分的作用来解释碱能使界面张力下降至超低值的传统观点是不完善的,加入碱能使高分子表面活性剂胶束解缔,胶束数量增多,胶束粒径减小,单分子自由链增加,有利于高分子表面活性剂向界面迁移和排布,这是高分子表面活性剂和碱复配体系与原油界面张力下降至超低值的主要原因.     

Ultrahigh‐molecular‐weight‐polyethylene‐fiber surface treatment by electron‐beam‐irradiation‐induced graft polymerization and its effect on adhesion in a styrene–butadiene rubber matrix

Aiming to develop a high‐performance fiber‐reinforced rubber from styrene–butadiene rubber (SBR), we applied a special technique using electron‐beam (EB)‐irradiation‐induced graft polymerization to ultrahigh‐molecular‐weight‐polyethylene (UHMWPE) fibers. The molecular interaction between the grafted UHMWPE fibers and an SBR matrix was studied through the evaluation of the adhesive behavior of the fibers in the SBR matrix. Although UHMWPE was chemically inert, two monomers, styrene and N‐vinyl formamide (NVF), were examined for graft polymerization onto the UHMWPE fiber surface. Styrene was not effective, but NVF was graft‐polymerized onto the UHMWPE fibers with this special method. A methanol/water mixture and dioxane were used as solvents for NVF, and the effects of the solvents on the grafting percentage of NVF were also examined. The methanol/water mixture was more effective. A grafting percentage of 16.4% was the highest obtained. This improved the adhesive force threefold with respect to that of untreated UHMWPE fibers. These results demonstrated that EB irradiation enabled graft polymerization to occur even on the inert surface of UHMWPE fibers. However, the mechanical properties of the fibers could be compromised according to the dose of EB irradiation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2595–2603, 2004     

Mechanical properties of rigid polyurethane composites reinforced with surface treated ultrahigh molecular weight polyethylene fibers

The mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE) fibers reinforced rigid polyurethane (PU) composites were studied, and the effects of the fiber surface treatment and the mass fraction were discussed. Chromic acid was used to treat the UHMWPE fibers, and polyurethane composites were prepared with 0.1 to 0.6 wt% as‐received and treated UHMWPE fibers. Attenuated total reflection Fourier transform infrared demonstrated that oxygen‐containing functional groups were efficiently grafted to the fiber surface. The mechanical performance tests of the UHMWPE fibers/PU composites were conducted, and the results revealed that the treated UHMWPE fibers/PU composites had better tensile, compression, and bending properties than as‐received UHMWPE fibers/PU composites. Thermal gravimetric analyzer showed that the thermal stability of the treated fiber composites were improved. The interface bonding of PU composites were investigated by scanning electron microscopy and dynamic mechanical analysis, and the results indicated that the surface modification of UHMWPE fiber could improve the interaction between fiber and PU, which played a positive role in mechanical properties of composites.     

高分子表面活性剂P(AM-co-OPMA)的合成与表征

辛基酚聚氧乙烯醚(10)(OP-10)与马来酸酐在95℃下反应,合成了辛基酚聚氧乙烯醚马来酸单酯(OPMA);并在水溶液中与丙烯酰胺(AM)单体进行共聚合,获得了高分子表面活性剂P(AM-co-OPMA);考察了引发剂用量、单体组成、单体总浓度及反应温度对共聚物特性粘数与阴离子度的影响.通过红外光谱、紫外光谱、荧光发射光谱和电导滴定对共聚物结构和组成进行了表征;利用视频光学接触角测量仪分别测定了共聚物表面和界面张力.结果表明,在聚丙烯酰胺分子主链上引入OPMA链节后,不仅保持了PAM优良的增稠能力(特性粘数达764.31 mL/g),且赋予了共聚物较高的表面活性(浓度为1.5 g/L共聚物水溶液的表面和界面张力分别可达53.94 mN/m和5.41 mN/m).     

Effect of surface treatment of UHMWPE fiber on mechanical and impact fracture behavior of PTFE/POM composites

Ultra‐high‐molecular‐weight polyethylene (UHMWPE) fiber was treated to reinforce the polytetrafluoroethylene/polyoxymethylene (PTFE/POM), and the mechanical properties of surface‐treated UHMWPE were investigated. Scanning electron microscopy was utilized to study the fracture surfaces of UHMWPE/POM/PTFE composites. Experimental results showed that the surface treatment of UHMWPE fiber effectively improves the mechanical property of POM/PTFE composites. Scanning electron microscopy studies indicated that surface modification could improve the interfacial adhesion of POM/PTFE composites. And the dispersion of UHMWPE in POM/PTFE composites was also improved after the surface modification. Copyright © 2017 John Wiley & Sons, Ltd.     

含氟丙烯酸酯共聚物防粘剂的制备及其表面性能研究

以甲基异丁基甲酮为溶剂,偶氮二异丁腈为引发剂,全氟烷基乙基丙烯酸酯、丙烯酸十八酯、丙烯酸丁酯和甲基丙烯酸羟乙酯为原料,溶液聚合制得了均一的含氟丙烯酸酯共聚物防粘剂,并研究了其表面性能。结果表明:全氟烷基乙基丙烯酸酯单体的加入显著降低了共聚物的表面能,提高了共聚物膜的硬度、耐水、耐碱、耐溶剂等性能。当加入ω(氟单体)为30%时,表面能降低至14.7 mN/m,低于有机硅类防粘剂的表面能,含氟丙烯酸酯共聚物膜与压敏胶的的剥离力较低,剩余粘附率为93.2%,该共聚物膜的防粘等综合性能最好。     

Interfacial mechanisms governing cyclopentane clathrate hydrate adhesion/cohesion

The present work uses a micromechanical force apparatus to directly measure cyclopentane clathrate hydrate cohesive force and hydrate-steel adhesive force, as a function of contact time, contact force and temperature. We present a hydrate interparticle force model, which includes capillary and sintering contributions and is based on fundamental interparticle force theories. In this process, we estimate the cyclopentane hydrate tensile strength to be approximately 0.91 MPa. This hydrate interparticle force model also predicts the effect of temperature on hydrate particle cohesion force. Finally, we present the first direct measurements of hydrate cohesive force in the gas phase to be 9.1 ± 2.1 mN/m at approximately 3 °C (as opposed to 4.3 ± 0.4 mN/m in liquid cyclopentane).