Surface modification and interfacial properties of polysulfonamide fiber treated by air plasma

The surface of polysulfonamide (PSA) fiber was modified by air plasma to improve its wettability and interfacial bonding performance. The surface morphology and chemical composition of the fiber were then evaluated with fieldemission scanning electron microscopy (FESEM) and X-ray photoelectron spectrometry (XPS). Moreover, the wettability and interfacial bonding performance of fiber before and after air plasma treatment were examined by water absorption time and interfacial shear strength (IFSS). FESEM observation confirmed that PSA fiber surface roughened with prolonged treatment duration. XPS analysis showed that the O/C atomic ratio on the PSA fiber surface can be increased from 19.69 % to 38.59 % after 3 min of treatment. Water absorption time dropped from as much as 400 s to about 0 s, indicating that the wettability of the fiber greatly improved. Under the experimental conditions of 40 Pa pressure, 100 W power, and 3 min treatment duration, IFSS increased by 57.01 %, and the interfacial bonding performance of fiber greatly improved.     

Preparation and characterization of (POSS/TiO2)n multi-coatings based on PBO fiber surface for improvement of UV resistance

The application of poly (p-phenylene-2, 6-benzobisoxazole) (PBO) fiber as reinforcement in composite material was restricted by its photo-degradation, therefore, some measures should be considered to protect PBO fiber against UV aging. In this study, A series of multilayer coating for (POSS/TiO₂)_n was prepared on PBO fiber surface via LbL assembly technique for enhancement of UV resistance. TiO₂ as UV absorbing material was used to relieve UV-degradation of PBO. Surface elemental composition, surface morphology, mechanical and interfacial properties, and UV resistance of uncoated and coated PBO fibers were investigated. These experimental results show multilayer coating of (POSS/TiO₂)_n was uniform deposition on fiber surface after treatment, tensile strength decreased to certain extent, interfacial shear strength increased in a small range and UV resistance is obvious enhanced. After the same accelerated aging time under UV irradiation, the retention of tensile strength and intrinsic viscosity of coated PBO fibers were much better than that of untreated PBO fibers.     

Improved interfacial properties of carbon fiber/epoxy composites through graphene oxide-assisted deposition of carbon nanotubes on carbon fiber surface

A useful reinforcement for carbon fiber (CF) composites was found by performing the assisted electrophoretic deposition (EPD) of graphene oxide (GO) for carbon nanotubes (CNTs) onto the CF surface. GO-assisted EPD of CNTs was conducted without the use any other pre-treatment or additives in order to avoid destroying the structure of the CNTs and to facilitate preparation of stable dispersion that was suitable for EPD. The presence of GO-CNTs may effectively increase both the roughness and wettability of the CF surface, resulting in an improvement to the interfacial bonding strength between the CF and the epoxy (EP). In contrast to the pristine CF/EP composite, the GO-CNTs/CF/EP composite exhibited a 64.6 % increase in interlaminar shear strength. Meanwhile, the water absorption of the composites decreased from 0.36 wt.% to 0.14 wt.%. The variable surface morphology, surface roughness, surface free energy and surface chemical composition of the CF were considered to have had an effect on the interfacial properties of the CF/EP composites; these effects could be seen using atomic force microscopes, scanning electron microscopes, X-ray photoelectron microscopes and contact angle analysis characterizations.     

Processing and characterization of polyacrylonitrile/soy protein isolate/polyurethane wet-spinning solution and fiber

Using dimethyl sulfoxide (DMSO) as a solvent, the polyacrylonitrile/soy protein isolate/polyurethane (PAN/SPI/PU) blend solutions and wet-spun fibers were prepared. The rheological properties of the PAN/SPI/PU solution were investigated. Investigations of the structure and properties of the PAN/SPI/PU fibers involved Fourier transform infrared, enzymatic hydrolysis, scanning electron microscopy, mechanical properties, dye adsorption, contact angle, and moisture regain measurements. The results showed that all PAN/SPI/PU solutions possess pseudoplastic properties, and there are opposite effects of SPI and PU in the PAN/DMSO solution. The apparent viscosity, the amount of non-Newtonian fluid and the extent of structuralization of the PAN/DMSO solution increase with the addition of SPI, whereas these features all decrease with the addition of PU. The biodegrability, the absorption of acidic dye and the moisture regain increase with the proportional increase in weight of SPI in the fiber blend.     

Study on the surface modification of PBO fiber under dielectric barrier discharge treatment

In order to improve the interfacial adhesion property between Poly(p-phenylene benzobisoxazole) (PBO) fiber and epoxy, the surface modification effects of PBO fiber under dielectric barrier discharge treatments in different time were investigated. The samples were tested for surface morphology, functional groups, surface wettability and interfacial shear strengths (IFSS) in epoxy using scanning electron microscope, Fourier transform infrared spectroscopy, water contact angle measurements and Micro-bond pull out tests, respectively. The results indicated that fiber surface morphology after plasma treatment was rougher than untreated one. Some polar groups were introduced on fiber surface in plasma treatment. Moreover, surface wettability and the IFSS between fiber and epoxy had much improvement after plasma treatment, the contact angle decreased with the treatment time increasing and reached the lowest value when the treated time was 60 s, and the IFSS was improved by 117.3 %. On the other hand, no significant difference in single fiber tensile test was observed between treated and untreated fibers when the processing time was shorter than 75 s, but the tensile strength declined by more than 10 % after 75 s treatment as a result of the excessive plasma etching.     

Morphological and thermal properties of maize fiber composites

Maize stalk has become one of the major sources of fibers from the agricultural residues. Use of these fibers as a reinforcement in the polymer is described in this paper. The present work is focused on establishing the properties such as physical, chemical, morphological structure and thermal properties of maize stalk fiber using different characterization techniques. Simple hand layup method was followed for processing the composite material. Chemical treatments of fibers were carried out to study the interaction of fibers with the matrix. The results revealed that maize fibers can also be used as a traditional fiber as reinforcement in a natural fiber reinforced composite materials.     

Surface characterization of sputter silver-coated polyester fiber

The present study concerns modification of surface of polyester fiber by magnetron sputtering using a silver (Ag) target. A detailed characterization of the silver-coated polyester fiber was investigated by scanning electron microscopy (SEM), X-ray diffraction technique (XRD) and X-ray photoelectron spectroscopy (XPS). The results revealed the remarkable changes in the surface morphology and microstructure of silver film on polyester fiber after sputtering for 10 and 30 min respectively. The SEM results showed that the silver particles were uniformly and densely deposited on the surface of polyester fiber. The XRD pattern of silver coated fabric showed that silver film is polycrystalline structure and dominated by the very strong (220) peak. Depth profiling results of silver coated fabric by XPS indicated that mainly metallic silver is existed throughout the whole depth region.     

Polyurethane smart fiber with shape memory function: Experimental characterization and constitutive modelling

Segmented polyurethane (PU) polymers are known to have shape memory function, i.e., when they reach certain temperatures, they deform into the memorized shape from any temporary one. In the present study, PU polymers were spun into fibers using the conventional extrusion process to investigate the feasibility of producing smart fibers with shape memory function. The shape memory polymers (SMPs) and their spun fibers were characterized using DSC, DMTA, and tensile test. In particular, the thermo-mechanical deformation behavior, which enables to evaluate the shape memory performance of the SMPs, was characterized using DMTA. Then, the linear viscoelastic theory was utilized for mathematical modelling of the thermo-mechanical behavior of the SMPs. For the shape memory fibers, the large deformation characteristics were also investigated using the thermo-mechanical test, necessitating the development of nonlinear viscoelastic theory to formulate a constitutive equation and to provide an effective tool for designing smart textile structure.     

Thermal stability and physical properties of epoxy composite reinforced with silane treated basalt fiber

This study evaluates the influence of different silane coupling agents on the thermal and physical properties of epoxy-anhydride composite reinforced with basalt fiber. The silane coupling agents were selected by their functional groups so that they could have different chemical interactions with the epoxy and anhydride curing agents. The thermal and degradation behavior of the composites with different fiber contents were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Through the evaluation of T _g and thermal degradation behavior of both systems, it was deduced that the silane coupling agents have a great influence on the thermal properties of the composites as well as interfacial improvement. Also, the tensile properties of the composites were systematically evaluated in order to further understand the effect of silane coupling agents on the interaction with basalt fiber and epoxy matrix.     

Enhanced mechanical and thermal properties of carbon fiber composites with polyamide and thermoplastic polyurethane blends

In this article, we demonstrated the preparation of carbon-fiber-reinforced composites using a polyamide 6 (PA6)/thermoplastic polyurethane (TPU) blend, in which the addition of TPU resulted in superior mechanical performances and increased thermal stability. According to various characterization techniques, these results are attributed to an enhanced adhesion and a homogeneous dispersion of long-carbon-fibers (LCFs) with TPU sizing in blended polymer matrix. Above all, dynamic-mechanical thermal analysis (DMTA) measurements clearly show that the dynamic storage modulus (E') of the blend composites is increased by threefold with temperature ranges below and above the glass transition temperature. The presence of LCFs in TPU systems induces effective fiber orientation, exhibiting simultaneous improvements in the tensile strength, flexural strength, and thermal stability.     

Mechanical properties of fragrant screwpine fiber reinforced unsaturated polyester composite: Effect of fiber length,fiber treatment and water absorption

Fragrant screwpine fiber reinforced unsaturated polyester composites (FSFRUPC) were subjected to water immersion tests in order to examine the effect of water absorption on the mechanical properties. FSFRUP composite specimen containing 30 % fiber volume fraction with fiber length of 3 mm and 9 mm was considered in this study. Water absorption test was performed by immersing specimen in sea, distilled and well water at room temperature under different time durations (24, 48, 72, 96, 120, 144, 168, 192, 216, 240 hours). The tensile, flexural and impact properties of the water absorption specimen were appraised and compared with those of the dry composite specimen as per the ASTM standard. The tensile, flexural and impact properties of FSFRUPC specimen were found to decrease with the increase in the percentage of moisture uptake. The percentage of moisture uptake of composite was reduced after alkali treatment with 3 % NaoH for 3 hours. In moisture absorption test, the lowest diffusion coefficient, D (6.62513×10^-13 m²/s) and swelling rate parameter, K _sr (6.341×10^-3 h^-1) were obtained through the specimen immersed in sea water. The chemical composition, elemental composition of fiber and surface morphology of the FSFRUPC were analysed by using Fourier transform infrared spectroscopy (FTIR), Energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) respectively.     

Effect of ionizing and non-ionizing preirradiations on physico-mechanical properties of coir fiber grafting with methylacrylate

Coir fibers were modified with methyl acrylate (MA) mixed with methanol (MeOH) under thermal curing method at different temperatures (40?C80 °C) for different curing times (20?C60 min). A series of solutions of different concentrations of MA in methanol along with 2 % benzoyl peroxide, were prepared. Monomer concentration, curing temperature, and curing time were optimized with the extent of grafting of monomer and mechanical properties of cured fiber and found to be 30 % MA, 60 °C and 40 min curing time registered as better performance (Grafting (Gr) = 5.7 %, tensile strength (TS) = 72 %, elongation at break (Eb) = 88 %) than those of untreated fiber. For further improvement of the properties, untreated coir fibers were pretreated with gamma and UV radiations at different doses and then pretreated fibers were soaked in the optimized monomer and cured under optimum conditions. Coir fiber pretreated with UV radiation and grafted with optimized monomer showed the best properties such as Gr (7.12 %), TS (132 %), and Eb (153 %) over raw fiber. Water uptake and simulated weathering test of untreated and treated coir fibers were studied.     

Preparation and properties of flame-retardant viscose fiber containing phosphazene derivative

The object of this work is to develop a flame-retardant viscose fiber containing phosphazene derivative. Hexaphenoxycyclotriphosphazene (HPTP) was synthesized and applied to viscose fiber through wet spinning method, with alkyl polysaccharide glycoside as dispersant. Properties of the fiber were tested and discussed. All flame-retardant samples survived 3 ignitions, according to 45 degree slope burning method. Limiting oxygen index value of the flame-retardant fiber containing 16% flame retardant was 28.6 %. The number decreased to 27.5 % after 30 washing cycles. After burning, inflated carbonized coat was found on the fiber surface in scanning electron microscopy image. Thermal gravimetric analysis and differential scanning calorimetry results indicated that the primary decomposition of fiber was moved up by about 20°C, while secondary decomposition was delayed by around 46°C. Damage on mechanical properties of fibers was insignificant. The introduction of HPTP was compatible and the flame retardancy of viscose fiber was greatly improved with limited negative impact.     

The nutritional properties of extruded and non-extruded corn fiber isolate

The feed efficiency and selected organ weights of rats fed diets containing 3 or 7% corn fiber, extruded corn fiber or silica were compared to rats fed a fiber-free diet. No significant differences were found in feed efficiency, spleen, lung or liver weights for any of the treatments relative to the fiber-free control diet.     

Surface characterization of low temperature plasma treated wool fiber

Previous investigation results revealed that after the Low Temperature Plasma (LTP) treatment, the hydrophilicity of wool fiber was improved significantly. Such improvement enhances the wool dyeing and finishing processes which might be due to the changes of the wool surface to a more reactive one. In this paper, wool fibers were treated with LTP with different gases, namely, oxygen, nitrogen and gas mixture (25 % hydrogen/75 % nitrogen). Investigations showed that chemical composition of wool fiber surface varied differently with the different plasma gas used. The surface chemical composition of the different LTP-treated wool fibers was evaluated with different characterization methods, namely FTIR-ATR, XPS and saturated adsorption value. The experimental results were thoroughly discussed.     

Mechanical,thermal and interfacial properties of green composites from basalt and hybrid woven fabrics

Composites based on pure Basalt and Basalt/Jute fabrics were fabricated. The mechanical properties of the composites such as flexural modulus, tensile modulus and impact strength were measured depending upon weave, fiber contents and resin. Dynamic mechanical analysis of all composites were done. From the results it is found that pure basalt fiber combination maintains higher values in all mechanical tests. Thermo-gravimetric (TG/DTG) composites showed that thermal degradation temperatures of composites shifted to higher temperature regions compared to pure jute fabrics. Addition of basalt fiber improved the thermal stability of the composite considerably. Scanning electron microscopic images of tensile fractured composite samples illustrated that better fiber-matrix interfacial interaction occurred in hybrid composites. The thermal conductivity of composites are also investigated and thermal model is used to check their correlation.     

Synthesis and characterization of novel reactive dyes with simultaneous insect-repellent and anti-bacterial properties

N,N-Diethyl-m-toluamide (DEET) is widely used as an insect-repellent. Sulfonamides are an important class of anti-bacterial drugs. In order to combine the strength of anti-bacterial activities of sulfonamides and insect-repellent property of DEET, three azo reactive dyes were designed and synthesized. To do this, the diazoniom salts of sulfonamides viz. 4-amino-N-(4-methyl-2-pyrimidinyl) benzene sulfonamide, 4-amino-N-(4-dimethyl-2-pyrimidinyl) benzene sulfonamide and 4-amino-N-(4,6-dimethyl-2-pyrimidinyl) benzene sulfonamide were prepared using HCl and NaNO₂. The resulting diazoniom salts were then coupled to the coupling component containing N,N-diethyl-m-toluamide to produce the novel dyes. The synthesized dyes were filtered off and then purified. To investigate and analyze the dyes, analytical methods such as ¹H-NMR, FTIR, UV-visible spectroscopy, and elemental analysis were used. Consequently, the anti-bacterial activities of dyes were measured with E. coli and P. aeruginosa as a Gram-negative strain and S. aureus and S. mutans as a Gram-positive strain according to MIC method. The insect-repellent efficacy of the dyes was studied using standard methods for Anophle mosquito repellent. The results confirmed anti-bacterial and insect-repellent activity of the dyes.     

Effect of coir fiber content and compatibilizer on the properties of unidirectional coir fiber/polypropylene composites

The main objective of this research was to study the effect of fiber content variation and stearic acid (SA) treatment on the fundamental properties of unidirectional coir fiber (CF) reinforced polypropylene (PP) composites. Several percentages of filler contents were used (10–40 wt %) in order to gain insights into the effect of filler content on the properties of the composites. Coir/PP composites were fabricated by compression molding, and the properties of composites were studied by physico-mechanical and thermal properties. The results from mechanical properties such as tensile strength (TS), tensile modulus (TM) and impact strength (IS) of the CF/PP composites were found to be increased with increasing fiber content, reached an optimum and thereafter decreased with further increase in fiber content. Treatment of the coir with SA as the coupling agent enhanced the mechanical properties, crystallization temperature and crystallinity of virgin PP and water desorption of the resulting composites, resulting from the improved adhesion between the CF and PP matrix. Scanning electron micrographs (SEM) of the tensile fractured samples showed improved adhesion between fiber and matrix upon treatment with SA. Interfacial shear strength (IFSS) of the composites was measured by single fiber fragmentation test (SFFT).     

Photochromic properties of rare-earth strontium aluminate luminescent fiber

The phase, luminescence spectrum, chromaticity and afterglow properties of rare-earth strontium aluminate luminescent fibers, which appear the primary colors of red, yellow and blue in the sun, were measured by XRD, fluorescence spectrometer, spectral scanning-meter and illuminometer. With the analysis, the experiment results indicated that the emission peak of yellow and blue luminescent fibers were located at 520 nm, which were caused by transition of Eu²⁺. The crystal phase structure of red luminescent fiber was destructed, the yellow light emission being created at 580 nm. This may be the transition of Dy³⁺ of rare-earth strontium aluminate. The three kinds of chromatic light of fiber are yellow, yellow-green and green light successively (The illumination strength is declining with the order of rare-earth strontium aluminate, yellow, blue and red). Comparing to rare-earth strontium aluminate, the afterglow duration of luminescent fibers were extended.     

Dyeing properties of nylon 66 nano fiber with high molecular mass acid dyes

Research and development of nano fiber products is very active over the world. Physical characteristics and dyeing properties of nylon 66 nano fiber were investigated in this study. X-ray diffraction, DSC, analysis of amino end group, and water absorption were performed to get information concerning physical properties of nano fiber. Nylon 66 nano fiber was dyed with high molecular mass acid dyes. Effects of dyeing temperature, pH of dyeing solution, and concentration of acid dyes on dyeing properties such as rate of dyeing and the extent of exhaustion, were examined and compared to those of regular fiber. It was found that nano fiber adsorbed acid dyes at lower temperature, got rapidly dyed, and its extents of exhaustion at specific dyeing temperature were higher than regular fiber. It was also observed that nano fiber could adsorb a large amount of acid dye without a significant loss in the extent of exhaustion. Washing fastness of the dyed nano fiber was lower by 1/2∼1 grade, light fastness by 1 grade than the dyed regular fiber.