Influence of absorbed moisture on antifelting property of wool treated with atmospheric pressure plasma

To determine the effect of moisture regain of wool on atmospheric pressure plasma treatment results, wool fibers and fabrics conditioned in 100% relative humidity (RH) and 65% RH were treated by an atmospheric pressure plasma jet with pure helium and helium/oxygen mixed gas, respectively. Scanning electron microscope (SEM) indicated that scales of wool fiber were smoothened for fibers conditioned in the 100% RH. X‐ray photoelectron spectroscopy (XPS) showed that carbon content decreased substantially after the plasma treatment. Surface chemical composition of 100% RH conditioned groups changed more significantly than the 65% RH conditioned groups. Water contact angle decreased significantly after the plasma treatments. In shrinkage test, plasma‐treated wool fabrics preconditioned in 100% RH showed the lowest shrinkage ratios of 5% and 6%, below 8% is required for machine‐washable wool fabrics according to ISO standard. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of Moisture on Effectiveness of Plasma Treatments of Polymer Surfaces

Abstract

In atmospheric pressure plasma treatments water molecules in the substrate material may disrupt the molecular arrangement in the substrate and thus greatly influence the outcome of the plasma treatment. This paper summarizes the results of our recent studies on how moisture influences the etching, surface chemical modification, crystallinity and aging of aramid, ultrahigh molecular weight polyethylene (UHMWPE), polyamide fibers, and poly(vinyl alcohol) (PVA) films. Overall, a higher moisture regain often results in a greatly enhanced etch rate, less surface chemical composition change, increased near-surface crystallinity, which could lead to a higher surface wettability, higher interfacial shear strength between the fibers and resin, decreased water solubility for PVA films, and delayed hydrophobic recovery of plasma treated fibers. Therefore, it is important to control the moisture contained in the substrate in atmospheric pressure plasma treatments.     

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.     

Effects of atmospheric pressure helium/air plasma treatment on adhesion and mechanical properties of aramid fibers

In order to investigate the effect of atmospheric pressure plasmas on adhesion between aramid fibers and epoxy, aramid fibers were treated with atmospheric pressure helium/air for 15, 30 and 60 s on a capacitively-coupled device at a frequency of 5.0 kHz and He outlet pressure of 3.43 kPa. SEM analysis at 10 000× magnification showed no significant surface morphological change resulted from the plasma treatments. XPS analysis showed a decrease in carbon content and an increase in oxygen content. Deconvolution analysis of C1s, N1s and O1s peaks showed an increase in surface hydroxyl groups that can interact with epoxy resin. The microbond test showed that the plasma treatment for 60 s increased interfacial shear strength by 109% over that of the control (untreated). The atmospheric pressure plasma increased single fiber tensile strength by 16-26%.     

Laser scanning confocal microscope characterization of dye diffusion in nylon 6 fibers treated with atmospheric pressure plasmas

The effect of atmospheric pressure plasma treatment on wettability and dyeability of nylon 6 fibers is investigated. The plasma treatments resulted in an average of 10°–20° decrease in the advancing contact angle and 20°–30° decrease in the receding contact angle. An increased dye diffusion rate of nylon 6 fibers was observed using laser scanning confocal microscope (LSCM). Scanning electron microscope confirmed that the fiber surfaces were roughened, and X‐ray photoelectron spectroscopy showed that the polar groups on the fiber surfaces increased after the plasma treatments. As the plasma treatment time increased, a greater degree of etching was achieved and more polar groups such as hydroxyl and carboxyl groups produced on the surfaces of the nylon 6 fibers, leading to a better wettability and thus a better dyeability of the fiber. This study proved that LSCM may be effectively used in detecting the change of dye diffusion rate in nylon fibers treated with plasmas and the mounting medium should have a close refractive index as the fiber to avoid distortion of the fiber cross section image. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The effect of atmospheric‐pressure air plasma discharge power on adhesive properties of aramid fibers

After exposure to the atmospheric‐pressure air plasma at different discharge powers, the adhesion characteristics of Twaron aramid fibers were investigated. For the 12 s‐300 W plasma treatment, the interlaminar shear strength of Twaron fiber reinforced thermoplastic poly(phthalazinone ether sulfone ketone) was increased from 46.0 to 61.7 MPa by 34.1%, and the diffusion of water molecule into the resulting composites was proved to be effectively prevented. These results showed that surface adhesive properties of the plasma‐treated aramid fibers were improved. At the power level of 300 W, X‐ray photoelectron spectroscopy analysis revealed the increases in concentrations of oxygen and nitrogen polar groups on the fiber surface, and atomic force microscopy observations led to the conclusion that the fiber surface morphology was changed and the surface roughness was greatly increased. These new polar and irregular surface structures accounted for the better adhesion between the fiber and the matrix, while due to the reasonability of this discharge power level applied to the surface modification, the measured fiber tensile strength only decreased by 2.0%. POLYM. COMPOS., 37:620–626, 2016. © 2014 Society of Plastics Engineers     

Ammonia‐gas and liquid ammonia treatments of silk fabric

Silk fabric, Habutae, was treated with 100% ammonia‐gas under atmospheric pressure and at pressures of 2, 4, and 6 kgf/cm², and with liquid ammonia at ?33°C. The effects of the treatment were investigated on the basis of the X‐ray diffraction, DSC thermogram, moisture regain, water absorption, dyeing property, and mechanical property of the fabric. Crystallinity and equilibrium dye uptake were increased apparently by the liquid ammonia treatment, whereas effect of the ammonia‐gas treatment was less than the liquid ammonia treatment. KES (Kawabata Evaluation System) shearing, bending, and tensile parameters were obtained. The modulus G, B, and hysteresis widths 2HG, 2HG5, and 2HB were decreased with the ammonia‐gas treatment. On the contrary, the liquid ammonia treatment increased the parameters considerably. Therefore, it seemed that the ammonia‐gas treatment is effective in enhancing the soft hand of the silk fabric. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3487–3492, 2006     

常压等离子体改善合成纤维吸湿性的研究

用氦气作为等离子体的气体源、对涤纶、锦纶6、高强度聚乙烯纤维,Twaron 1000芳纶4种合成纤维进行常压等离子体处理,改善纤维的吸湿性能。结果表明:常压等离子体处理,对涤纶和锦纶6的表面有一定的刻蚀作用,但对高强度聚乙烯纤维、Twaron 1000芳纶的表面没有明显影响;经常压等离子体处理后,合成纤维表面氧、氮有所增加,吸湿性能得到提高,强度没有显著变化。     

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     

Atmospheric Plasma Surface Activation of Poly(Ethylene Terephthalate) Film for Roll-To-Roll Application of Transparent Conductive Coating

An effective surface activation is crucial for high-speed roll-to-roll coating of functional films for printed electronics applications. In this article, we report a study of surface treatment of three types of poly(ethylene terephthalate) (PET) films by an argon/oxygen atmospheric pressure plasma and an ambient air atmospheric pressure plasma to obtain the required wettability for subsequent slot die coating of transparent conductive polymer layer using a poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) ink. Prior to plasma treatment, the PET surfaces, which differ in manufacturing process of their preparation, were characterized by X-ray photoelectron spectroscopy. The surface changes after the plasma treatments were characterized by water contact angle measurement and atomic force microscopy. We found that the water contact angles of the three types of untreated PET surfaces were 80.9°, 75.9°, and 66.3°, respectively, and the water contact angles after argon/oxygen plasma treatment at treatment speed of 1 m · min^?1 decreased to 36.2°, 31.9°, and 40.9°, respectively. These conditions were stable from 1 up to 4 days, which are longer than reported values of 15–60 min and sufficient for roll-to-roll coating processes.     

Functional finishing of nonwoven fabrics. I. Accessibility of surface modified PET spunbond by atmospheric pressure He/O2 plasma treatment

The surface of a polyethylene terephthalate (PET) spunbond nonwoven was modified by using atmospheric pressure He/O₂ plasma treatment. Accessibility of the modified PET nonwoven has been investigated in terms of crystallinity, surface chemical composition, hydrophilicity, and dye uptake. Differential scanning calorimetry (DSC) for crystallinity measurement and X‐ray photoelectron spectroscopy (XPS) for chemical composition measurement were used. Surface morphology was studied by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Percentage crystallinity increased due to the depletion of amorphous region by plasma etching. Redeposition of etched particles was observed. Oxygen‐based functional groups on the surface of PET increase from 27 to about 32% after 90 s exposure. Wettability increases by more than 10 times and moisture regain increases by three times, compared with the untreated sample. Dye uptake was not changed significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4306–4310, 2006     

Surface modification of aramid fibers via ammonia‐plasma treatment

In this article, aramid fibers III were surface modified using an ammonia‐plasma treatment to improve the adhesive performance and surface wettability. The surface properties of fibers before and after plasma treatment were investigated by X‐ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and water contact angle measurements. The interfacial shear strength of each aramid fibers III‐reinforced epoxy composites was studied by micro‐debonding test. The ammonia‐plasma treatment caused the significant chemical changes of aramid fibers III, introducing nitrogen‐containing polar functional groups, such as ? C? N? and ? CONH? , and improving their surface roughness, which contributed to the improvement of adhesive performance and surface wettability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40250.     

Surface modification of nylon 6 films treated with an He/O2 atmospheric pressure plasma jet

To investigate the effect of the gas composition of the plasma treatment on the surface modification of an atmospheric pressure plasma jet (APPJ), nylon 6 films were treated with APPJ with pure helium (He), He + 1% oxygen (O₂), and He + 2% O₂, respectively. Atomic force microscopy showed increased surface roughness, whereas X‐ray photoelectron spectroscopy revealed increased oxygen contents after the plasma treatments. The plasma‐treated samples had lower water contact angles and higher T‐peel strengths than the control. The addition of a small amount of O₂ to the He plasma increased the effectiveness of the plasma treatment in the polymer surface modification in terms of surface roughness, surface oxygen content, etching rate, water contact angle, and bonding strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of aging on the adhesive properties of poly(lactic acid) by atmospheric air plasma treatment

The aim of this study was to analyze the durability of a plasma treatment on the surface of poly(lactic acid) (PLA). We used atmospheric‐plasma treatment with air to improve the wettability of PLA by evaluating the aging effect under controlled conditions of relative humidity (RH) and temperature (25% RH and 25°C). We studied the durability of the atmospheric‐plasma treatment by measuring the contact angle, calculating the surface energy, and observing changes in the resistance of the PLA–PLA adhesive bonds. These techniques allowed us to evaluate the hydrophobic recovery phenomenon that the PLA surface suffered as a consequence of the aging process. The results provide the maximum storage time of PLA treated with atmospheric plasma at which the sample retained its good adhesion properties; this time was lower than 3 days under normal atmospheric conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43040.     

Interfacial studies on the surface modified aramid fiber reinforced epoxy composites

In this work, solutions of rare earth modifier (RES) and epoxy chloropropane (ECP) grafting modification method were used for the surface treatment of aramid fiber. The effect of chemical treatment on aramid fiber has been studied in a composite system. The surface characteristics of aramid fibers were characterized by Fourier transform infrared spectroscopy (FTIR). The interfacial properties of aramid/epoxy composites were investigated by means of the single fiber pull‐out tests. The mechanical properties of the aramid/epoxy composites were studied by interlaminar shear strength (ILSS). As a result, it was found that RES surface treatment is superior to ECP grafting treatment in promoting the interfacial adhesion between aramid fiber and epoxy matrix, resulting in the improved mechanical properties of the composites. Meanwhile, the tensile strengths of single fibers were almost not affected by RES treatment. This was probably due to the presence of reactive functional groups on the aramid fiber surface, leading to an increment of interfacial binding force between fibers and matrix in a composite system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4165–4170, 2006     

Time‐dependent changes of surface properties of polyether ether ketone caused by air plasma treatment

The effect of air plasma treatment on wetting and energy properties, surface composition and morphology of polyether ether ketone (PEEK) was investigated. The influence of the storage time on the surface properties of plasma‐treated polymer plate was also examined. The properties were determined by advancing and receding contact angle measurements, Fourier transform infrared spectroscopy supported by theoretical spectrum modelling, X‐ray photoelectron spectroscopy and optical profilometry. Three theoretical approaches were used in the determination of the apparent surface free energy of the untreated and plasma‐treated PEEK samples from the measured contact angles of probe liquids (water, formamide, diiodomethane): the contact angle hysteresis method, the Owens and Wendt approach and the Lifsthitz ? van der Waals acid–base approach. It was found that air plasma treatment of PEEK causes significant chemical and morphological changes of the polymer surface, which are reflected in the decrease of contact angles from 83.4° to 11.7° for water after 180 s plasma treatment. This is due to the formation of polar functional groups resulting in the increase of the surface hydrophilicity. After plasma treatment the apolar component of the surface free energy practically does not change, while the polar component increases significantly, especially for plates treated for 180 s, from 0 to 19.6 mJ m^?2. In addition, the modified PEEK surface is not stable during storage and it acquires more hydrophobic character. © 2016 Society of Chemical Industry     

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.     

Adhesive joints between carbon fiber and aluminum foam reinforced by surface‐treated aramid fibers

Short aramid fibers have been successfully used to reinforce the interface adhesive property between carbon fiber/epoxy composites and aluminum foam, and to form aramid‐fiber “composite adhesive joints.” In this study, to further improve the reinforcing effect of the aramid‐fiber‐reinforced adhesive joints, aramid fibers were ultrasonic treated to conduct different surface conditions. Critical energy release rate of the carbon fiber/aluminum foam sandwich beams with as‐received and treated interfacial aramid fibers were measured to study the influence of the surface treatment on aramid fibers. It was found that reinforcements in critical energy release rate were achieved for all samples with treated aramid fiber as measured under double cantilever beam condition. The interfacial characteristics of the short aramid fibers with different surface condition were investigated and discussed based on scanning electron microscopy observations. It is suggested that advanced bonding between aramid fibers and epoxy resin was conducted after surface treatment, and more energy was therefore absorbed through fiber bridging during crack opening and extension process. POLYM. COMPOS., 36:192–197, 2015. © 2014 Society of Plastics Engineers     

Barrier properties for short‐fiber‐reinforced epoxy foams

The barrier properties of short‐fiber‐reinforced epoxy foam are characterized and compared with unreinforced epoxy foam in terms of moisture absorption, flammability properties, and impact properties. Compression and shear properties are also included to place in perspective the mechanical behavior of these materials. Compared with conventional epoxy foam, foam reinforced with aramid fibers exhibits higher moisture absorption and lower diffusion, while glass‐fiber‐reinforced foam is significantly stiffer and stronger. In addition, the polymeric foam composites studied present superior fire‐resistance compared with conventional epoxy foam systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3266–3272, 2006     

Experimental characterization of contact angle and surface energy on aramid fibers

In this paper, both contact angles and surface energy of aramid fibers are investigated using the liquid droplet method. First, the contact angles between matrix resin and aramid fibers are measured at different degrees of cure, which indicate that the contact angles increased initially and then decreased after the consolidation. Second, surface energy components of aramid fibers are determined from the contact angle using the geometric-mean equations. Finally, the influences of various surface treatments on the surface energy of aramid fibers are analyzed. These results play an important role for designing and evaluating the fiber/matrix interfacial strength of aramid fiber-reinforced composites.