氧气低温等离子体对PBO纤维的表面改性

采用氧气低温等离子体对聚对苯撑苯并双噁唑(PBO)纤维进行表面改性,讨论了处理时间、处理功率及气压对PBO纤维单丝强度、与环氧树脂基体的界面剪切强度(π_(IFSS))、形态结构、表面元素组成和亲水性的影响。结果表明:在处理时间为2.5 min,处理功率为30 W,处理气压为50 Pa的最佳工艺条件下,经氧气等离子处理后的PBO纤维与环氧树脂的π_(IFSS)比原丝提高60%,达9.38 MPa,与水的接触角也从105°下降到72°。     

Promoting the adhesion of high‐performance polymer fibers using functional plasma polymer coatings

Plasma‐copolymerized functional coatings of acrylic acid and 1,7‐octadiene were deposited onto high strength, high modulus, poly‐p‐phenylene benzobisoxazole (PBO) fibers. X‐ray photoelectron spectroscopy (XPS) with trifluoroethanol derivatization confirmed that the PBO fibers were covered completely with the plasma copolymer and that the coating contained a quantitative concentration of carboxylic acid groups. Microdebond single filament adhesion and interlaminar shear strength (ILSS) tests were used to evaluate the interfacial strength of epoxy resin composites containing these functionalized PBO fibers. Both the interfacial shear strength (IFSS) obtained from single filament tests, and the ILSS of high volume fraction composites were a function of the surface functionality of the fibers so that there was a good correlation between ILSS and IFSS data. The tensile strengths of single fibers with or without coating were comparable, demonstrating that the fiber surface was not damaged in the plasma‐coating procedure. Indeed, the statistical analysis showed that Weibull modulus was increased. Therefore, plasma‐polymerized coatings can be used to control the interfacial bond between PBO fibers and matrix resins and act as a protective size for preserving the mechanical properties of the fibers. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Improvement of the interfacial shear strength of poly(p‐phenylene benzobisoxazole) fiber/epoxy resin composite via a novel surface coating agent

Poly(p‐phenylene benzobisoxazole) (PBO) fiber with a smooth surface exhibits limited interfacial interaction with resin matrix. One of the effective strategies to improve the adhesion between the fiber and resin matrix is through surface modification of the fiber. In this study, we have proposed a novel surface treatment agent based on phosphoester cross‐linked castor oil (PCCO) for effective surface treatment of PBO fibers. The surface treatment agent was prepared by a simple cross‐linking reaction between hydroxy phosphorylated castor oil (PCO) and epoxy resin, with alcohol as the solvent at 65°C. Once the PBO fiber was treated with this agent, the interfacial adhesion between the PBO fiber and the epoxy resin could then be improved. Systematic analyses suggest that the surface treatment with (PCO + epoxy)/alcohol solution improves the interaction of the PBO fiber with the epoxy resin matrix. The PCCO coated onto the surface of PBO fiber acts as a coupling agent, improving the interfacial shear strength (IFSS) of the PBO fiber/epoxy resin composite. Results indicate a 156% increase in IFSS without compromising the mechanical properties of the fiber. POLYM. COMPOS., 37:1198–1205, 2016. © 2014 Society of Plastics Engineers     

低温等离子体处理对PBO纤维润湿性的影响

为改善PBO纤维的润湿性,拓宽其应用领域,探究了空气低温等离子体处理对PBO纤维润湿性的影响。通过芯吸效应和接触角表征处理前后PBO纤维润湿性,并采用扫描电子显微镜SEM观察处理前后PBO纤维表面形貌,用X射线光电子能谱仪(XPS)对处理前后PBO纤维表面化学组成进行定性分析。实验结果表明,改性后PBO纤维芯吸高度大幅上升,接触角明显降低,并且在其表面产生明显刻痕,局部有剥离现象,改性后PBO纤维O、N元素含量均有所提高,PBO纤维润湿性明显增强。()     

Influence of oxygen plasma treatment on interfacial properties of poly(p‐phenylene benzobisoxazole) fiber‐reinforced poly(phthalazinone ether sulfone ketone) composite

The influence of oxygen plasma treatment on both surface properties of poly(p‐phenylene benzobisoxazole) (PBO) fibers and interfacial properties of PBO fiber reinforced poly(phthalazinone ether sulfone ketone) (PPESK) composite were investigated. Surface chemical composition, surface roughness, and surface morphologies of PBO fibers were analyzed by X‐ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. Surface free energy of the fibers was characterized by dynamic contact angle analysis (DCAA). The interlaminar shear strength (ILSS) and water absorption of PBO fiber‐reinforced PPESK composite were measured. Fracture mechanisms of the composite were examined by SEM. The results indicated that oxygen plasma treatment significantly improved the interfacial adhesion of PBO fiber‐reinforced PPESK composite by introducing some polar or oxygen‐containing groups to PBO fiber surfaces and by fiber surface roughening. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Argon low‐temperature plasma modification of chopped aramid fiber and its effect on paper performance of aramid sheets

Chopped aramid fiber was modified by an argon low‐temperature plasma treatment to enhance the interfacial strength of aramid paper. The water contact angle of the aramid fiber and the tensile strength, tearing strength, and evenness of the aramid sheets were investigated under different conditions, and the parameters of the argon low‐temperature plasma modification, like gas pressure, discharge power, and discharge time, were optimized. The chemical structure and surface morphology of the fiber after plasma modification were characterized by X‐ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy. The strengthening mechanism of aramid paper by low‐temperature plasma modification was also studied. It was found that the argon low‐temperature plasma treatment introduced some new polar groups onto the fiber surface and increased the fiber surface wettability and roughness. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45215.     

Interfacial shear strength and wettability between glass fiber and PC/SAN/SMA blends

The two important factors affecting the mechanical properties of fiber‐reinforced composite materials are the interfacial shear strength (IFSS) and wettability. The IFSS and wettability of glass fiber in a polycarbonate (PC)/styrene‐co‐acrylonitrile (SAN) blend system were measured by the single fiber fragmentation test (SFFT) and the Wilhelmy method, respectively. Styrene‐co‐maleic‐anhydride (SMA) was used as a compatibilizer and the glass fiber was surface‐treated with organosilane coupling agents to induce chemical bonding between maleic anhydride and silanol. The IFSS was found to increase with the content of SMA copolymer and then level off: There was an optimum level of the SMA content for a given silanol content. The IFSS and wettability increased with increasing SAN content, and the wettability showed quite similar behavior to the case of the IFSS with respect to SAN content. The effect of the miscibility of SAN/SMA blends on the IFSS was also investigated. The IFSS was greatly affected by the miscibility of SAN/SMA blends, which is mainly dependent on the copolymer compositions of SAN and SMA. Higher IFSS was obtained when the SAN/SMA blend was miscible.     

Improvement of interfacial adhesion between PBO fibers and cyanate ester matrix

Poly(p‐phenylene benzobisoxazole) (PBO) fibers were activated by the horseradish peroxidases (HRP) and then treated by 3‐Glycidoxypropyltrimethoxysilane (KH‐560) to improve the wettability and the interfacial adhesion between PBO fibers and cyanate ester matrix. The chemical compositions of PBO fibers were characterized and analyzed by FTIR and XPS. Surface morphologies of PBO fibers were examined by SEM. The wettability of PBO fibers was evaluated by the dynamic contact angle analysis test. The mechanical properties were evaluated by tensile strength and interfacial shear strength, respectively. The results demonstrated that hydroxyl groups and epoxy groups were introduced onto the surface of PBO fibers during the treatments. These treatments can effectively improve the wettability and adhesion of PBO fibers. The surface free energy of PBO fibers was increased from 31.1 mN/m to 55.2 mN/m, and the interfacial adhesion between PBO fiber and cyanate ester resin was improved to 10.77 MPa. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40204.     

Surface modification of ultra-high strength polyethylene fibers for enhanced adhesion to epoxy resins using intense pulsed high-power ion beam

The effects of intense pulsed high power ion beam (HPIB) treatment of ultra-high strength polyethylene (UHSPE) fibers on the fiber/epoxy resin interface strength were studied. For this study, argon ions were used to treat Spectra? 1000 (UHSPE) fibers in vacuum. Chemical and topographical changes of the fiber surfaces were characterized using Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), dynamic wettability measurements, and scanning electron microscopy (SEM). The fiber/epoxy resin interfacial shear strength (IFSS) was evaluated by the single fiber pull-out test. The FTIR-ATR and XPS data indicate that oxygen was incorporated onto the fiber surface as a result of the HPIB treatment. The wettability data indicate that the fibers became more polar after HPIB treatment and also more wettable. Although the total surface energy increased only slightly after treatment, the dispersive component decreased significantly while the acid-base component increased by a similar amount. SEM photomicrographs revealed that the surface roughness of the fibers increased following the HPIB treatment. The single fiber pull-out test results indicate that HPIB treatment significantly improved the IFSS of UHSPE fibers with epoxy resin. This enhancement in IFSS is attributed to increased roughness of the fiber surface resulting in mechanical bonding and in increased interface area, increased polar nature and wettability, and an improvement in the acid-base component of the surface energy after the HPIB treatment.     

Surface modification of armos fibers with oxygen plasma treatment for improving interfacial adhesion with poly(phthalazinone ether sulfone ketone) resin

We introduce in this article oxygen plasma treatment as a convenient and effective method for the surface modification of Armos fibers. The effects of oxygen‐plasma‐treatment power on both the Armos fiber surface properties and Armos‐fiber‐reinforced poly(phthalazinone ether sulfone ketone) composite interfacial adhesion were investigated. The Armos fiber surface chemical composition, surface morphology and roughness, and surface wettability as a function of oxygen‐plasma‐treatment power were measured by X‐ray photoelectron spectroscopy, scanning electronic microscopy, atomic force microscopy, and dynamic contact angle analysis. The results show that oxygen plasma treatment introduced a lot of reactive functional groups onto the fiber surface, changed the surface morphology, increased the surface roughness, and enhanced the surface wettability. Additionally, the effect of the oxygen‐plasma‐treatment power on the composite interfacial adhesion was measured by interlaminar shear strength with a short‐beam bending test. Oxygen plasma treatment was an effective method for improving the composite interfacial properties by both chemical bonding and physical effects. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of temperature and relative humidity on aging of atmospheric plasma jet treatment effect on ultrahigh-modulus polyethylene fibers

The aging effects of atmospheric pressure plasma treated fiber surfaces are important for storage and processing of the fibers. One of the high-performance fibers, ultrahigh modulus polyethylene (UHMPE) fiber, was chosen as a model system to investigate the aging process of atmospheric pressure plasma jet (APPJ) treated fibers surfaces 0, 7, 15 and 30 days after initial plasma treatment. The fiber was first plasma-treated and then stored at temperatures varying from ?80 to 80°C on the same relative humidity (RH, 0%) and on RH of 0%, 65% and 100% at the same temperature of 20°C. Immediately after the plasma treatment, scanning electron microscope (SEM) showed the roughened fiber surface. X-ray photoelectron spectroscopy analysis showed changed surface chemical compositions. Contact-angle measurement showed increased surface wettability and microbond test showed an increase in IFSS. With increasing relative humidity or decreasing temperature, the IFSS value decreased and the contact angle increased more slowly. However, after 30 days, the IFSS values and contact angles reached a similar level for all groups. Moisture showed no effect on the single fiber tensile strengths during aging. The reasons for the observed aging behavior could be that decreasing temperature or increasing relative humidity hindered the surface rearrangement of polymer chains after plasma treatment.     

Wettability assessment of plasma-treated PBO fibers based on thermogravimetric analysis

Changes in the surface wettability of poly(p-phenylene benzobisoxazole) (PBO) fibers were investigated by thermogravimetric analysis (TGA) following an air dielectric barrier discharge (DBD) plasma treatment. The results were then supplemented and confirmed by scanning electron microscopy (SEM), dynamic contact angle analysis (DCAA), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements. After exposure to the DBD plasma at a pre-determined power level, TGA analysis showed that the residual rates retained by the PBO composites decreased, which meant an increase in the amount of resin coating the PBO fibers in the composites. Observations by SEM confirmed that there was more resin adhering to the treated PBO fibers and the wetting behavior of resin on the fibers was greatly improved. Meanwhile, DCAA for the treated fibers showed a significant enhancement in fiber surface free energy. XPS and AFM were performed in order to reveal any variations in fiber surface activity and surface morphology resulting from the surface treatment. The resulting data showed that increases in oxygen-containing polar groups and surface roughness on the plasma-treated PBO fibers contributed to the above improved wetting behavior. With comprehensive analyses, it was concluded that TGA could be used as a supporting method assessing the surface wettability of PBO fibers before and after air DBD plasma treatment.     

低温等离子体对PBO纤维表面的改性

采用硅烷偶联剂处理聚对苯撑苯并双噁唑(PBO)纤维,利用常压射频低温等离子体对PBO纤维进行了表面处理,通过扫描电镜、红外光谱、光学显微镜等研究了处理时间对PBO纤维表面官能团和表面形貌的影响规律,通过单丝拔出实验测定PBO纤维基复合材料的界面剪切强度。结果表明:经过常压射频低温等离子体处理后,PBO纤维的表面形成了大量的极性基团,表面产生明显的凹坑,PBO纤维与树脂的粘接性能提高50%,纤维的拉伸强度下降5%。     

The effect of silica (SiO2) nanoparticles and ammonia/ethylene plasma treatment on the interfacial and mechanical properties of carbon-fiber-reinforced epoxy composites

A nanoparticle dispersion is known to enhance the mechanical properties of a variety of polymers and resins. In this work, the effects of silica (SiO₂) nanoparticle loading (0–2 wt%) and ammonia/ethylene plasma-treated fibers on the interfacial and mechanical properties of carbon fiber–epoxy composites were characterized. Single fiber composite (SFC) tests were performed to determine the fiber/resin interfacial shear strength (IFSS). Tensile tests on pure epoxy resin specimens were also performed to quantify mechanical property changes with silica content. The results indicated that up to 2% SiO₂ nanoparticle loading had only a little effect on the mechanical properties. For untreated fibers, the IFSS was comparable for all epoxy resins. With ethylene/ammonia plasma treated fibers, specimens exhibited a substantial increase in IFSS by 2 to 3 times, independent of SiO₂ loading. The highest IFSS value obtained was 146 MPa for plasma-treated fibers. Interaction between the fiber sizing and plasma treatment may be a critical factor in this IFSS increase. The results suggest that the fiber/epoxy interface is not affected by the incorporation of up to 2% SiO₂ nanoparticles. Furthermore, the fiber surface modification through plasma treatment is an effective method to improve and control adhesion between fiber and resin.     

Effect of Surface Modification on Mechanical and Tribological Performance of Poly-p-phenylenebenzobisoxazole Fiber-Reinforced Polyimide Composite

This work examined the effect of coupling agent surface modification of Poly-p-phenylenebenzobisoxazole (PBO) fibers on mechanical and tribological performance of PBO fiber-reinforced thermoplastic polyimide (PBO/PI) composites. The results show that tensile strength and flexural strength are largely improved by coupling agent treatment. Under dry sliding conditions, coupling agent treatment is effective to reduce the wear of PBO/PI composite. The principle of improvement in interfacial adhesion between PBO fiber and PI matrix after coupling agent treatment was discussed. The surface characteristics of PBO fibers were characterized by X-ray photoelectron spectroscopy (XPS). It is found that the content of polar groups on the surface of PBO fiber treated by coupling agent increases compared with the untreated fiber. The presence of polar groups is probably leading to an increment of interfacial binding force between fibers and matrix in a composite system, and accordingly enhances the mechanical and tribological properties.     

Surface modification of ultra high modulus polyethylene fibers by an atmospheric pressure plasma jet

To improve their adhesion properties, ultra high modulus polyethylene (UHMPE) fibers were treated by an atmospheric pressure helium plasma jet (APPJ), which was operated at radio frequency (13.56 MHz). The surface properties of the fibers were investigated by X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and contact angle measurement. The surface dyeability improvement after plasma treatments was investigated using laser scanning confocal microscopy (LSCM). The adhesion strengths of the fibers with epoxy were evaluated by microbond tests. In addition, the influence of operational parameters of the plasma treatment including power input and treatment temperature was studied. XPS analysis showed a significant increase in the surface oxygen content. LSCM results showed that the plasma treatments greatly increased fluorescence dye concentrations on the surface and higher diffusion rate to the fiber center. The tensile strength of UHMPE fiber either remained unchanged or decreased by 10–13.6% after plasma treatment. The contact angle exhibited a characteristic increase in wettability, due to the polar groups introduced by plasma treatment. The microbond test showed that the interfacial shear strengths (IFSS) increase significantly (57–139%) after plasma treatment for all groups and the optimum activation is obtained at 100°C and 5 W power input. SEM analysis showed roughened surfaces after the plasma treatments. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Carbon nanotubes grafting PBO fiber: A study on the interfacial properties of epoxy composites

To improve the interfacial performance of poly[p‐phenylene benzobisoxazole] (PBO) fiber and epoxy resin, a modified multiwalled carbon nanotubes (MWCNTs‐Ecp) were used to achieve this purpose through grafting onto PBO fiber surface using a gamma ray radiation method. Experimental results indicated that the equilibrium wetting rate and equilibrium adsorption amount of the modified PBO fiber for epoxy resin and acetone were all higher than that of as received PBO fiber. The interfacial shear strength (IFSS) of single fiber composite increased from 31.4 to 77.5 MPa after modification. The fracture models of composites are changed from pure interfacial failure to combination failure of interface and resin interlayer. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Structures and properties of HMPBO fibers treated by oxygen plasma/polyhedral oligomeric silsesquioxane

The surface of high modulus poly(p‐phenylene‐2,6‐benzobisoxazole) (HMPBO) fibers were treated by the combination method of oxygen plasma/polyhedral oligomeric silsesquioxane (POSS). The chemical compositions and surface morphologies of HMPBO fibers were characterized by Fourier transform infrared, X‐ray photoelectron spectroscopy, thermogravimetric analyzer, and scanning electron microscopy. The interfacial shearing strength (IFSS) of the HMPBO/cyanate ester (HMPBO/CE) micro‐composites was measured by single fiber pull out test. Results showed that the POSS was grafted on the surface of HMPBO fibers, and the grafting amount was about 0.82 wt%. After the treatment, the HMPBO fibers became coarser and the diameter was also increased. Compared with that of pure HMPBO/CE micro‐composites, the IFSS of treated HMPBO/CE micro‐composites was increased by 20.7%. POLYM. COMPOS., 34:2026–2030, 2013. © 2013 Society of Plastics Engineers     

Improvement of interfacial shear strengths of polybenzobisoxazole fiber/epoxy resin composite by n‐TiO2 coating

Smooth polybenzobisoxazole (PBO) fiber has limited interfacial interaction with resin matrix. In this article, nano‐TiO₂ coating on PBO fiber is applied to improve the interfacial adhesion between PBO fiber and epoxy resin. The test results suggest that the PBO fiber had good interaction with epoxy resin matrix after its treatment with n‐TiO₂ sol. Nano TiO₂ particle embedded onto PBO fiber surface, acting as a chock, which made fiber implanted into the resin better. This greatly improved the shear strengths (IFSS) of PBO fiber/epoxy resin composite. It has been found that a 56% increase in interfacial IFSS has achieved without sacrificing mechanical properties of fiber. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Wettability enhancement of polystyrene with electron cyclotron resonance plasma with argon

Polystyrene cell‐culture substrates were treated with argon glow discharge to make their surfaces hydrophilic. The process was novel in that it used a microwave electron cyclotron resonance (ECR) source for polymer surface modification. The substrates were processed at different microwave powers and time periods, and the surface modification was assessed with by measurement of the water contact angle. A decrease in contact angle was observed with increasing microwave power and processing time. Beyond a certain limit of power and duration of exposure, however, surface deterioration occurred. The optimum conditions for making the surfaces hydrophilic without deterioration of the samples were identified. The plasma parameters were assessed by Langmuir probe measurement. Fourier transform infrared spectroscopy with attenuated total reflectance showed evidence for the induction of hydrophilicity on the surface. The surface micromorphology was examined with scanning electron microscopy. The results prove that the ECR glow discharge was an efficient method for enhancing the wettability of the polymer surfaces. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1618–1623, 2003