Effects of nanoclay and short nylon fiber on morphology and mechanical properties of nanocomposites based on NR/SBR

Natural rubber and styrene butadiene rubber (NR/SBR) reinforced with both short nylon fibers and nanoclay (Cloisite 15A) nanocomposites were prepared in an internal and a two roll-mill mixer by a three-step mixing process. The effects of fiber loading and different loading of nanoclay (1, 3 and 5 wt. %) were studied on the microstructure and mechanical properties of the nanocomposites. The adhesion between the fiber and the matrix was improved by the addition of a dry bonding system consisting of resorcinol, hexamethylene tetramine and hydrated silica (HRH). This silicate clay layers was used in place of hydrated silica in a HRH bonding system for SBR/NR-short nylon fiber composite. Nanoclay was also used as a reinforcing filler in the matrix-short fiber hybrid composite. The cure and scorch times of the composites decreased while cure rate increased when the short fiber and nanoclay were added. The mechanical properties of the composites showed improvement in both longitudinal and transverse directions with increasing short fiber and nanoclay content. The structure of the nanocomposites was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM). X-ray diffraction results of nanocomposites indicated that the interlayer distance of silicate layers increased. The mechanical properties of nanocomposites (tensile, hardness and tear strength) are examined and the outcome of these results is discussed in this paper.     

Nanofibrillation of cotton fibers by disc refiner and its characterization

Nanofibrils of cellulose were prepared from short staple cotton by refining process using a lab disc refiner that exerts a combination of shear and frictional forces. The nanofibrils were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). From SEM and AFM, it was found that starting average diameter of the cotton fiber (∼25 μm) was reduced to 242 nm after 30 passes of refining. FTIR analysis revealed the increase in amorphous nature of cotton cellulose due to refining process. Supportively, XRD analysis showed a steady decline in percent crystallinity of the cotton fibers as the cotton fibres were passed through the refiner for more number of passes. Similarly, degree of polymerization (DP) was reduced from 2720 to 740 due to the refining process. Nanofibrils of cellulose from short staple cotton have a huge potential for application in nanofilters and as biodegradable fillers in nanocomposites.     

Various nano-silica particles affecting dyeability of poly(ethylene terephthalate)/silica nanocomposite films

Poly(ethylene terephthalate) [PET] based nanocomposites containing three differently modified silica particles were prepared by melt compounding. The influence of type of nano-silica on dispersibility, thermal and dyeing properties of the resultant nanocomposite was investigated by various analytic techniques, namely, polarized optical microscopy (POM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), reflectance spectroscopy (RS), and light fastness. Optical microscopy images illustrated that nano-silica particles tended to increase the number of spherulites in the PET matrix which were dependent on nano-silica type and content. Thermal studies of the resultant nanocomposites showed a slight decrease in the melting temperature compared to a pristine PET. Silica nanocomposites were finally dyed with a disperse dye and their reflectances were determined by the aid of reflectance spectrophotometer. Such reflectances were converted to the corresponding color coordinate values which are indicative of dyeability of such nanocomposites.     

Mechanism and Analysis of Laccase-mediated Coloration of Silk Fabrics

Laccase provides a mild and eco-friendly alternative for the dyeing of fabrics. In this study, laccase-mediated catalytic oxidation was employed in coloration of silk fabrics, and the color was then assessed. The surfaces of silk fabrics were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). Their thermal and crystallization properties were also investigated by differential scanning calorimetry (DSC), thermogravimetry (TG), and Xray diffraction (XRD). The textile softness was evaluated by the bending rigidity (B). In addition, high performance liquid chromatography (HPLC) and ultraviolet-visible (UV-VIS) spectroscopy were employed to analyze hydrolysate of silk fabrics obtained from hydrolysis with hydrochloric acid solution. The results demonstrated that a stable reddish-yellow layer was formed on the surface of silk fabrics by the laccase-mediated coupling of phenol hydroxyl side chains in the silk polypeptide. Moreover, the SEM and AFM observations showed that the surface of colored silk fiber was slick. ATR-FTIR and XPS results demonstrated differences in the C, N, O contents and the functional groups of the uncolored and colored silk fabrics. The DSC, TG, and XRD indicated that the thermal properties of silk fabrics were not affected by laccase and the coupling reaction mainly occurred in the amorphous region. The DMF extraction test further illustrated that covalent bonds were formed between tyrosine residues constituent of silk peptides. Finally, HPLC and UV-VIS results showed that new substances were formed as a result of conjugation between benzene rings.     

Modification of enzyme pretreated cotton fabric using acrylonitrile, acrylonitrile/solvent mixture and its characterization

The presented research deals with modifying the chemical structure of the bioscoured cotton fabric by acrylonitrile, acrylonitrile/acetone, and acrylonitrile/ethanol mixture. The modified cellulose was tested for weight gain, shrinkage, and wicking height and characterized by X-ray diffraction (XRD), thermal analysis (TG/DTA), elemental analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The weight gain and shrinkage % show increased value for modified fabrics. The wicking height increases with addition of solvent. The crystallinity and thermal studies show a significant change. FTIR analysis confirms the modification by the occurrence of -C??N stretching and -CONH₂ stretching. The SEM morphology of modified fabric shows uniform swelling of fibers with better smoothness. The AFM topography reveals that the addition of solvent affects the particle size. Clear surface morphology of modified fabric reveals that this processing method can be used for preparation of medical textiles with more swelling.     

A study of mechanical behavior and morphology of carbon nanotube reinforced UHMWPE/Nylon 6 hybrid polymer nanocomposite fiber

We report a phenomenal increase in strength, modulus, and fracture strain of ultra high molecular weight polyethylene (UHMWPE) fiber by 103 %, 219 %, and 108 %, respectively through hybridizing this fiber with Nylon 6 as a minor phase and simultaneously reinforcing it with single-walled carbon nanotubes (SWCNTs). Loading of Nylon 6 and SWCNTs into UHMWPE was 20.0 wt% and 2.0 wt%, respectively. Hybridized fibers were processed using a solution spinning method coupled with melt mixing and extrusion. We claim that the enhancement in strain-to-failure of the nanocomposites is due to induced plasticity in the hybridized Nylon 6-UHMWPE polymers. The enhancement in strength and stiffness in the nanocomposites is attributed to the load sharing of the SWCNTs during deformation. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) studies showed that changes in percent crystallinity, rate of crystallization, crystallite size, alignment of nanotubes, sliding of polymer interfaces and strong adhesion of CNT/polymer blends were responsible for such enhancements.     

SiO2-kaolinite affecting the surface properties of ternary poly(vinyl chloride)/silica/kaolinite nanocomposites

The products from the dispersion of nanoscale particulates such as the layered clays or the spherical inorganic minerals within the polymeric matrices are called polymeric nanocomposites. In this paper, we prepared poly(vinyl chloride) (PVC) based nanocomposites containing SiO₂-kaolinite by melt compounding. The influence of SiO₂-kaolinite on the surface properties of PVC was investigated by the use of various surface analysis techniques including a ttenuated total reflectance spectroscopy (ATR), wide angle X-ray diffractometry (WAXD), atomic force microscopy (AFM), scanning electron microscopy (SEM), electron dispersive X-ray spectrometer (EDX), contact angle measurement (CAM), and reflectance spectroscopy (RS). ATR spectroscopy showed possible interaction between layered kaolinite and PVC at surface. Microscopic methods illustrated an increased surface roughness compared to the pure PVC. Contact angle measurements of the resultant PVC nanocomposites demonstrated that the wettability of substrates depends on the surface interactions between kaolinite layers and PVC matrix. Optical properties of nanocomposite films were finally measured by the aid of reflectance spectrophotometer. It can be seen from optical studies that reflectance values were increased after incorporation of SiO₂-kaolinite in nanocomposite.     

Influence of natural clinoptilolite nanoparticles on thermal stability,scratch resistance and adherence properties of Acrylonitrile butadiene styrene (ABS)

In order to improve thermal stability of Acrylonitrile-butadiene-styrene (ABS) polymer, ABS/natural clinoptilolite (Clino) nanocomposite was produced using solvent/non-solvent method. The influence of natural clinoptilolite nanoparticles on scratch resistance and adherence properties of ABS coating on steel coupons was investigated. In order to study the scratch resistance and adherence properties, thin (20 µm) coatings of ABS and ABS/Clino nanocomposites, were prepared by solution casting method. The formation of ABS/Clino nanocomposite was characterized using FTIR spectroscopy, X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM). Results showed that there is a strong interaction such as hydrogen bonding between ABS and clinoptilolite nanoparticles. The thermal stability of the nanocomposite was examined using thermogravimetric analysis (TGA). TGA results showed an increase in the thermal degradation temperature of the nanocomposite. TGA results indicated that the thermal stability of ABS increases by increasing the Clino content of nanocomposite up to 5 % w/w. Scratch resistance and adherence properties of ABS/Clino nanocomposite coatings were also evaluated. Results showed that the scratch resistance and adherence strength of ABS/Clino nanocomposite coatings are higher than that of pure ABS coatings.     

Thermomechanical and Shape Memory Performances of Thermo-sensitive Polyurethane Fibers

This study is the first step to investigate usability of shape memory polyurethane (SMPU) fibers for smart garment applications. SMPU fibers were spun by wet spinning process and chemical/mechanical characterization was carried out. SMPU solutions were prepared with two different concentrations (20 % and 25 %) and three different coagulation bath concentrations (0 %, 1 % and 3 %) were used for determining optimum spinning parameters. For investigating influences of spinning process on crystal structure, mechanical, thermal and shape memory performances of fibers, X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and mechanical tests were conducted. DSC and DMA analysis results show that shape memory polyurethane fibers have a glass transition temperature about 35-40 oC which is suitable for body temperature. Moreover, SMPU fibers showed good tensile performance with an average tenacity of 1.38 cN/dtex and elongation at break of 350 %. Thermo mechanical test results showed that, all shape memory fibers have good shape memory effect with recovery and fixity ratios up to 91 % and 71 % respectively.     

Improved interfacial properties of carbon fiber/unsaturated polyester composites through coating polyhedral oligomeric silsesquioxane on carbon fiber surface

Carbon fibers were coated with E51 plus Methacryl-POSS together in an attempt to improve the interfacial properties between carbon fibers and unsaturated polyester resins matrix. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were performed to characterize the changes of carbon fiber surface. AFM results show that the coating of E51 plus POSS significantly increased the carbon fiber surface roughness. XPS indicates that silicon containing functional groups obviously increased after modification. Dynamic mechanical analysis was carried out to investigate the surface energy of carbon fiber. Force modulation atomic force microscopy (FMAFM) and Interlaminar shear strength (ILSS) were used to characterize the interfacial properties of the composites. ILSS was increased by 21.9 % after treatment.     

Mechanical behavior of composites reinforced with fibers caroa

Composites were prepared with 13, 23 30 and 40 % fiber and evaluated the mechanical performance in tensile, flexural and impact. The mechanical properties of these composites were also evaluated function of time at 110 °C thermal exposure. Caroa fibers were characterized by techniques such as thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the best mechanical properties were achieved for composites containing 23 to 30 % fiber. The incorporation of 23 % fiber caroa increased both the modulus of elasticity in the tensile test as the flexural strength and impact, the composite with 30 % fiber caroa showed higher tensile strength. The results show that the tensile and flexural strength of the composite decreased with time of thermal exposure. The thermal aging at 110 °C caused a decrease in tensile properties of the composites.     

Polypropylene/high-density polyethylene/carbon fiber composites: Manufacturing techniques,mechanical properties,and electromagnetic interference shielding effectiveness

This study uses polypropylene (PP)/high-density polyethylene (HDPE) polyblends (80/20 wt.%) as matrices, which are then melt-blended with inorganic carbon fibers (CF) as reinforcement to form electrically conductive PP/HDPE composites. Tensile test, flexural test, Izod impact test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) are performed to evaluate different physical properties of samples. A surface resistance and electromagnetic interference shielding effectiveness (EMI SE) measurements are used to evaluate the electrical properties of the PP/HDPE/CF composites. Test results show that an increasing content of carbon fibers results in an 18 %, 23 %, and 60 % higher tensile strength, flexural strength, and impact strength, respectively. SEM results show that carbon fibers break as a result of applied force, thereby bearing the force and increasing the mechanical properties of composites. DSC and XRD results show that the addition of carbon fibers causes heterogeneous nucleation in PP/HDPE polyblends, thereby increasing crystallization temperature. However, the crystalline structure of PP/HDPE composites is not affected. Surface resistivity results show that 5 wt.% of carbon fibers can form a conductive network in PP/HDPE polyblends and reduce the surface resistivity from 12×10¹² ohm/sq to 4×10³ ohm/sq. EMI SE results show that, with a 20 wt.% CF and a frequency of 2-3 GHz, the average EMI SE of PP/HDPE/CF composites is between -48 and -52 dB, qualifying their use for EMI SE, which is required for standard electronic devices.     

Preparation of magnetic and conductive graphite nanoflakes/SrFe<Subscript>12</Subscript>O<Subscript>19</Subscript>/polythiophene nanofiber-nanocomposites and its radar absorbing application

This study, we synthesized graphite-nanoflakes (GNFs) by acid treatment and thermal shock and then using the ultrasonic irradiation technique to exfoliate flake-carbon. The SrFe₁₂O₁₉ nanoparticles (NPs) were coated by co-precipitate method on GNFs after by alkaline treatment. Finally nanocomposite (GNF/SrFe₁₂O₁₉/PTh) was prepared by in-situ oxidative polymerization method in presence of thiophene (Th) as monomer. The magnetic and electrical conducting properties of the resulting nanocomposites were measured by using vibrating sample magnetometer and standard four-point-probe method, respectively. The synthesized nanocomposites were characterized by X-ray diffraction (XRD) and fourier transform infrared spectra (FTIR). In addition, morphological analyses were investigated by scanning electron microscopy (SEM). A minimum reflection loss (RL) of GNFs/SrFe₁₂O₁₉/PTh with 50 % wt GNFs/SrFe₁₂O₁₉ as core were observed ?28 and ?39 dB at 9.7 and 12 GHz for a 1.5 mm thickness. The results indicated that we can perform good microwave shielding in X-band (8–12 GHz) by these nanocomposites.     

Investigation of mechanical properties of developed antimicrobial PPsuture/Ag nanocomposite

In order to prevent surgical complications due to microbial infections, we have developed polypropylene suture grafted with silver nanoparticles (PPsuture/Ag nanocomposite) by a simple immersion procedure. Physical and mechanical properties of developed suture are investigated. Suture surface characteristics are examined by scanning electron microscopy (SEM) imaging and atomic force microscopy (AFM). Silver content on suture surface was determined by Inductively coupled plasma atomic emission spectroscopy (ICP-AES). The mechanical properties of developed antibacterial PP suture/Ag were studied. We note that proposed silver coating method has not affected mechanical performances of suture. Antimicrobial performances of PP suture/Ag nanocomposites against S. aureus and E. coli colonies were also investigated.     

Preparation and Characterization of Chitosan Poly(acrylic acid) Magnetic Microspheres

Spherical microparticles, capable of responding to magnetic fields, were prepared by encapsulating dextran-coated Fe₃O₄ nanoparticles into chitosan poly(acrylic acid) (PAA) microspheres template. The obtained magnetic microspheres were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and thermogravimetry (TG). The results showed that the microspheres were formed and demonstrated magnetic behavior in an applied magnetic field. In addition, magnetite particles were well encapsulated and the composite particles have high magnetite content, which was more than 40%.     

Novel high flux nanofibrous composite membrane based on polyphenylsulfone thin barrier layer on nanofibrous support

A novel thin film nanofibrous composite (TFNC) polyphenylsulfone (PPSU) membrane was fabricated by casting a thin PPSU barrier layer on the surface of the electrospun nanofibrous PPSU support. Polyethylene glycol (PEG) 400 was applied in the electrospinning solution to prevent the penetration of coating solution into the support. The membrane morphology and filtration performance were investigated via scanning electron microscopy (SEM), and filtration of canned beans production wastewater, respectively. Atomic force microscopy (AFM) was utilized to evaluate the surface roughness of the membranes. Furthermore, the mechanical strength and thermal stability of the membranes were determined via tensile test and thermogravimetric analysis (TGA). Comparison of the TFNC membrane and the unsupported membrane prepared through the wet phase inversion method with almost equal rejection values indicated a 2.3 fold higher PWF using the former.     

Synthesis and characterization of cellulose carbamate by liquid-solid phase method

An efficient and environmentally friendly method for the synthesis of cellulose carbamate from a mixture of cellulose pulp or the activated cellulose pulp and urea was presented in this paper. Cellulose carbamate with a nitrogen content of 1.21 % and 3.29 % were successfully synthesized via esterification reaction in the high-boiling aprotic and polar N-methyl-2-pyrrolidone solvents (hereinafter NMP). The structures of cellulose carbamate were characterized by Fourier transform infrared spectroscopy (FTIR), Kjeldahl analysis, thermo-gravimetric analysis, scanning electron microscopy (SEM), X-ray diffractometry (XRD), and ¹³C-solid-state NMR. The results showed that some functional groups of the alkali cellulose were substituted by amino in the high-boiling aprotic and polar solvents, then the cellulose carbamate was prepared with the reduced crystallinity and thermal decomposition temperature. In addition, the product was prepared with uniform substitution and distribution of carbamate group in the cellulose chain, which guaranteed its good solubility in aqueous alkali as well as its spinnability to produce fiber.     

The effects of wool surface characteristic on fuzzing and pilling of knitted fabrics

The fuzzing and pilling of untreated, chlorinated and oxidized wool knitted fabrics were compared with frictional coefficients measured by capstan method, surface modification observed by scanning electron microscopy (SEM), the surface roughness and the scale height assessed by atomic force microscopy (AFM), and hairiness imaged on the three-dimensional rotational microscopy. The pilling comparative experiments of the corresponding knitted fabrics were conducted by means of Pillbox method. Experimental results showed that some scales on the oxidized fiber surface were partially cleaved and some grooves generated. With oxidization treatment, the anti- and with-scale of friction coefficient increase with decreasing the thickness of scales and the yarn hairiness. There is good correlation between the result of AFM and the change in frictional coefficients. The pilling grade of knitted fabric comprised of oxidization wool is 2.5, and the average numbers of pills per 25 cm² is 25. It is postulated that the surface topography, the frictional properties of oxidized wool fibers and surface hairs of corresponding yarns may limit the ability of those surface fibers to form fuzz and of those fuzz for pill formation.     

POSS/polypropylene hybrid nanocomposite monofilaments by reactive extrusion

The Allyl-heptaisobutyl-polyhedral oligomeric silsesquioxane (AHO-POSS) grafted polypropylene (PP) was prepared by reactive extrusion and by physical blending routes. The structure and properties of physically blended and reactively blended POSS/PP nanocomposites were investigated by FTIR, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis, SEM, spherutlic growth and mechanical properties studies. Chemical bonding of POSS with PP in reactive extrusion was confirmed by FT-IR spectroscopy. DSC and TGA studies showed that the thermal stability of AHO-POSS/PP nanocomposite prepared by reactive extrusion improved significantly as compared to only physically blended nanocomposites. WAXD studies showed decrease in crystallinity of the AHO-POSS/PP nanocomposites prepared by reactive extrusion. SEM studies showed aggregation tendency in case of physically blended AHO-POSS/PP nanocomposites. Spherulite growth studies show reactive blending retards spherulite growth in PP polymer.     

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.