Crosslinking reactions of oxidized cellulose fiber. I. Reactions between dialdehyde cellulose and multifunctional amines on lyocell fabric

Fibrillation‐controlled lyocell fibers were developed by crosslinking reactions between dialdehyde cellulose (DAC) and multifunctional amines. DAC lyocell fibers were manufactured by partial oxidation with sodium metaperiodate and were successfully crosslinked with two multifunctional amines by Schiff‐base formation. The amorphous regions and the char formations, which were characterized by differential scanning calorimetry and thermogravimetric analysis, increased with the degree of oxidation. After the crosslinking reactions, an increase in the amorphous regions also appeared, whereas the thermal stability was somewhat improved by the chain crosslinking. These results were in good agreement with viscosity‐average degree of polymerization values in that they diminished with oxidation level and increased with the crosslinking reactions. The water retention value and moisture regain value decreased with the oxidation and crosslinking levels, which implied that the swellability of fibers and the water absorbency in characteristic sites decreased with them. The increase in the dry crease recovery angle also confirmed the presence of hemiacetal crosslinks in the DAC and amine crosslinks between the DAC and the amines. The fibrillation grade of the crosslinked fibers diminished with oxidation level and the amine concentration. In particular, the fibrillation properties of the crosslinked fibers with 4‐hydroxy‐2,4,6‐triaminopyrimidine sulfate salt were more easily controlled than those of the crosslinked fibers with 2,4,6‐triamino‐1,3,5‐triazine. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Multifunctional cotton fabric: Antimicrobial and durable press

2‐Amino‐2‐methyl‐1‐propanol (AMP) was coated onto cotton fabric with 1,2,3,4‐butanetetracarboxylic acid (BTCA) as a crosslinking agent to simultaneously impart antimicrobial and durable‐press functionalities. The coatings were characterized and confirmed by attenuated total reflectance–IR and thermogravimetric analysis. The coated fabrics were rendered biocidal upon exposure to dilute household bleach, and the chlorinated swatches exhibited about 6 log reductions of Escherichia coli O157:H7 and Staphylococcus aureus within 5 min of contact time. A concentration of 1.5 wt % AMP was sufficient to produce this biocidal efficacy. Increasing the BTCA content of the coating improved the wrinkle recovery angle. The coatings were very stable toward repeated laundering, and they exhibited sufficient halogen storage stabilities for industrial applications. A photolytic decomposition was observed when the coatings were exposed to UVA light. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Novel materials from unsaturated polyester resin/styrene/tung oil blends with high impact strengths and enhanced mechanical properties

A novel material was prepared through the blending of an unsaturated polyester resin/styrene mix with tung oil, which offered improved impact strength, creep resistance, modulus, and hardness. A nanoindentation technique was used to investigate the mechanical properties. With the incorporation of 1 wt % tung oil into the unsaturated polyester matrix, the impact strength, modulus, and hardness increased by 15, 20, and 41%, respectively. The impact‐fractured surfaces were examined with scanning electron microscopy. The dynamic mechanical analysis was performed with a nanoindentation technique. The storage and loss modulus values were determined under cyclic loading as a function of indentation. The flexural properties also significantly increased with the incorporation of tung oil. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Radiation‐induced crosslinking of ultra high molecular weight polyethylene fibers by means of electron beams

Crosslinking of ultra high molecular weight polyethylene fibers (UHMW‐PE fibers) is investigated by means of electron beam irradiation. The structure and mechanical properties of the fibers in different irradiation atmospheres are discussed. The results show that the gel fraction and crosslinking density increase with the increase of absorbed dose. The swelling ratio and average molecular weight of crosslinked net decrease with the increase of absorbed dose. The relation between s + s^?1 of the UHMW‐PE fibers and reciprocal irradiation dose 1/R is obtained. The tensile strength and failure elongation decrease with the increase of absorbed dose, and the tensile modulus increases with the increase of absorbed dose. The samples are irradiated in air, vacuum, and acetylene atmospheres, separately. The radiation effects, such as crosslinking fraction and mechanical properties of UHMW‐PE fibers, are the most significant in acetylene atmosphere in comparison with in air and in vacuum. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1761–1764, 2005     

Gauge length effect on the tensile properties of leather

Tensile properties are important basic characteristics of materials and influence their end‐use and performance. More importantly, in the case of leather due to end‐use applications such as shoe uppers, automotive and furniture upholstery, mechanical properties such as tenacity are of extreme importance. Therefore, fundamental studies on the tensile properties of leather are needed. In this study, an attempt has been made to examine the effect of gauge length (GL) on the tensile properties of shoe upper leather. Two different specimens in the form of rectangular and dumbbell shapes have been cut from parallel and perpendicular directions to the body axis of the leather and have been tested. Results showed that the maximum breaking load and the percentage extension at break decreased with the increase in GL. Rectangular specimens showed a 30% decrease in maximum breaking load and a 13% decrease in percentage extension at break, while dumbbell specimens showed reductions in the order of 28 and 6%, respectively, as the GL increased from 9.53 cm to 23.5 cm. Highly varying supramolecular architecture of the collagen matrix and the frictional slippage caused by the free ends present in the collagen fibrils, which induce a weak‐link effect similar to the one found in cotton fibers and yarns, are considered to be the probable reasons for this behavior. A limited scanning electron microscopic study has been undertaken to pictorially represent the breakage of leather at different GLs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1202–1209, 2006     

Surface and bulk analysis of bleaching soybean fabric in the presence of protein hydrolysate

The effect of oxidative and oxidative‐reductive bleaching on the colorimetric, topographical, and mechanical properties of soybean fabric has been investigated by yellowness index, abrasion resistance, tensile strength, Kawabata evaluation system for fabrics, scanning electron microscopy, X‐ray photoelectron spectroscopy, and time of flight secondary ion mass spectrometry in order to examine both the bulk and surface properties. Surface changes to the soybean fiber due to bleaching treatments have been evaluated and the protective effect of protein hydrolysates assessed. Improved tensile strength, flat abrasion performance, and handle maintenance of the soybean fabric was demonstrated with the incorporation of Byco C in both bleaching treatments. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

FTIR analysis of crosslinked cotton fabric using a ZnSe–universal attenuated total reflectance

Two cotton fabrics were treated with increasing amounts of a textile‐finishing agent (1,3‐dimethyl‐4,5‐dihydroxy‐2‐imidazolidinone) to impart durable press properties. The Universal Attenuated Total Reflectance Fourier Transform Infrared (UATR–FTIR) with a ZnSe–Diamond composite crystal was used to determine the amount of the crosslinking agent effectively linked to the cellulose after the required laundering cycles. Textile performance testing conducted on treated and untreated fabrics demonstrated the effectiveness of the treatment applied. The results obtained showed very good correlation between AATCC grading, automatic image analysis of fabric smoothness, textile performance testing, and the amount of finish as evaluated by the UATR–FTIR. The ZnSe–Diamond composite FTIR accessory was proven to be a fast and precise nondestructive technique to evaluate the amount of the crosslinking agent linked to the cellulose macromolecules. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 392–399, 2005     

Effect of the solvent type on the formation and physical properties of polyacrylonitrile fibers via a solvent‐free coagulation bath

Polyacrylonitrile (PAN) fibers were fabricated via a dry‐jet wet‐spinning technique, and a solvent‐free coagulation bath system was adopted. The effects of different types of dope solvent on the formation and physical properties of the PAN fibers were investigated. Dimethylformamide and dimethyl sulfoxide (DMSO) were selected as the solvents and were added to a spinning solution consisting of 18 wt % PAN. The PAN fibers were examined with field emission scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. The field emission scanning electron micrographs revealed that the PAN fibers with the DMSO solvent exhibited a more circular shape and a smoother skin. The PAN fibers with the DMSO solvent had their glass‐transition temperature (T_g) at 121°C. This study indicated that the different types of dope solvent used in the dope preparation did not affect T_g of the PAN fibers because of the solvent‐free coagulation bath system; however, they significantly affected the physical formation of the PAN fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Treatment of Harakeke fiber for biocomposites

The use of fiber from Harakeke (or New Zealand Flax plant) for the reinforcement of composites should be explored since Harakeke has similar properties to Sisal fiber. To maximize the cellulose content in the fiber, Harakeke fibers were prepared by thermal, combinative alkaline‐thermal, and a novel combinative thermal‐enzymatic‐thermal treatments and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and wide‐angle X‐ray spectroscopy. The characterization method provided an efficient and systematic method to evaluate the removal of amorphous components such as lignin and hemicelluloses. In particular, a sequential thermal‐enzymatic‐thermal fiber treatment produced fine discontinuous whiskers that could be useful for short fiber composites, whereas a combinative thermal‐alkaline treatment resulted in thorough extraction of lignin and hemicelluloses. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

HRTEM microstructures of PAN precursor fibers

Ultrathin sections prepared from both transverse and longitudinal PAN precursor fibers were examined by high-resolution transmission electron microscopy. Ordered and amorphous phases coexist in these sections, providing verification for the two-phase structure of PAN fibers, however, onion-like spheres and crystallites predominate in the transverse sections, and highly oriented structures are dominant in the longitudinal sections. The formation of the onion-like spheres can be ascribed to intramolecular and intermolecular dipolar nitrile group interactions. The larger area of oriented structures in the longitudinal sections is due to the coalescence of several ribbons with the approximative orientations. Some defects, such as pores and voids, have also been observed. These examinations provide not only some direct structural evidence but also some information for optimizing spinning technology and for deliberately controlling the microstructures to obtain PAN precursor fibers applicable to fabricating high strength carbon fibers.     

Improving the antibacterial activity of cotton fabrics finished with triclosan by the use of 1,2,3,4‐butanetetracarboxylic acid and citric acid

For producing antibacterial textiles, the conventional finishing processes have high productivity and low processing costs, but textiles finished in these ways exhibit low durability against laundering. Therefore, cotton fabrics were bleached with hydrogen peroxide, finished with triclosan, and then treated with polycarboxylic acids such as 1,2,3,4‐butanetetracarboxylic acid (BTCA) and citric acid (CA) as crosslinking agents to provide durable antibacterial properties. The surface of fibers treated with BTCA had a greater crosslinked area, and the surfaces of fabrics treated with CA were exposed to greater amounts of deformation due to the mechanical and chemical influences after 50 launderings. The bleaching and finishing treatments did not dramatically affect the breaking strength. However, the polycarboxylic acid treatment (both BTCA and CA) alone showed reductions in the breaking strength when the acid concentration was increased. The polycarboxylic acids were fairly effective against both bacteria, even at lower concentrations, when they were applied to stand‐alone cotton fabrics, whereas the antibacterial activity decreased somewhat after the use of polycarboxylic acid and triclosan in the same recipes. Adding polycarboxylic acids to the antibacterial finishing recipes enhanced the durability after 50 launderings, and the durability of the recipes containing BTCA was much higher than that of the recipes containing CA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Biodeterioration of coated nylon fabric

Biodegradation characteristics of nylon fabric coated with fluorocarbon polymer (oil and water repellent) and thiourea‐formaldehyde (fire retardant) were studied. The fabric was exposed to soil burial, air exposure, and standard culture media for various intervals of time and evaluated for changes in physicomechanical properties, oil and water repellency, air permeability, as well as flame‐retardant properties. Significant falls in these properties were observed, the extent of which was found to be maximum in the case of soil burial followed by air medium and standard culture. Themogravimetric analysis showed enhanced heat stability of the unexposed fabric compared with base nylon. Exposure of the coated fabric to various biomedia caused extensive damage of the fire retardant material and also resulted in a significant reduction in the flame‐resistant properties. Fluorocarbon material, on the other hand, did not degrade on bioexposure and its presence improved the thermal stability of the coated fabric. Fourier transform infrared spectroscopy showed remarkable changes, e.g., peak shifts, intensity variations, as well as elimination of peaks in the case of soil burial compared with the unexposed sample. Scanning electron microscopy was used to investigate the changes in the surface topography associated with the degradation of the coated fabric vis‐à‐vis those of the controlled one. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 685–691, 2000     

Radiation grafting/crosslinking of silk using electron‐beam irradiation

The radiation grafting of silk with methacrylamide (MAA) was studied using an electron‐beam (EB) irradiation technique. Two irradiation processes, preirradiation and coirradiation, were compared, and some factors affecting the degree of grafting were investigated. The radiation crosslinking of silk with dimethyloldihydroxyethylene urea (DMDHEU) was preliminarily studied. The physical and mechanical properties such as whiteness, breaking strength, and resilience of the radiation‐grafted/crosslinked silk fabrics were examined. The radiation grafting of silk with MAA increases the silk weight, while the radiation crosslinking of silk with DMDHEU imparts improved crease resistance to silk. X‐ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) analysis indicate the formation of peroxy and free‐radical species on the EB‐irradiated silk. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2028–2034, 2004     

Platinum and palladium ions adsorption at the trace amounts by radiation crosslinked carboxymethylchitin and carboxymethylchitosan hydrogels

Adsorption of palladium and platinum ions at the trace amounts onto radiation crosslinked carboxymethylchitin (CMCht) and carboxymethylchitosan (CMChts) has been investigated. Maximum adsorption capacities for palladium were 2.679 and 1.053 mg/g dry gel, whereas for platinum they were 2.513 and 1.155 mg/dry gel for CMCht and CMChts, respectively. Retention capacity values for palladium were 0.45 and 0.06; for platinum 0.25 and 0.11 mEquiv./g for CMCht and CMChts, correspondingly. It has been shown that adsorption of Pd and Pt ions onto both hydrogels were dependent on the chloric and nitric ions concentration. Desorption experiments in HCl and HNO₃ solutions proved that adsorption is governed by chelating mechanism rather than ion‐exchange one. SEM‐EDX spectroscopy showed that palladium and platinum ions were homogeneously distributed in all sections of hydrogel matrix. DSC experiments demonstrated decreasing in the decomposition temperature of polymers after inclusion of palladium and platinum ions, suggesting that metals are causing lowering of stability in polymer structural integrity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4015–4023, 2007     

Influence of mixing procedures and mica addition on properties of NR/BR vulcanizates. I

Elastomeric compositions of natural rubber (NR) and polybutadiene rubber (BR) in a 1 : 1 ratio (w/w), with mica in the range 0–30 phr, were investigated. For all compositions the same formulation was used but two different additives incorporation sequences were followed. The results of the tests showed that the mechanical performance is sequence‐dependent, as the two elastomers have very different rheometric characteristics. It was also observed that mica, when present in amounts of 20 and 30 phr, improves the mechanical properties. Scanning electron microscopy (SEM) permitted the observation of the fracture behavior of each composition, and dynamic mechanical thermal analysis (DMTA) suggested different migration tendencies of the additives in each phase, thus corroborating the differences found for the mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1575–1585, 2004     

Effect of mica addition on the properties of natural rubber and polybutadiene rubber vulcanizates

The rheometric, mechanical, and dynamic mechanical properties as well as fracture surfaces of natural rubber–mica and polybutadiene rubber–mica vulcanizates were studied. Mica was used in the range of 0–30 phr and the rheometric study was carried out at 160°C. The results indicate that the mechanical properties are improved as filler addition increases. Dynamic mechanical testing was used to analyze the observed mechanical behavior. The two elastomers showed different fracture behaviors. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2156–2162, 2003     

Development of conducting polyaniline/poly(lactic acid) nanofibers by electrospinning

Ultrafine fibers consisting of blends of polyaniline doped with p‐toluene sulfonic acid and poly(L ‐lactic acid) were prepared by electrospinning. The presence of polyaniline resulted in fibers with diameters as thin as 100–200 nm and a significant reduction of bead formation. These fibers were visually homogeneous, and this indicated good interactions between the components of the polyaniline/poly(L ‐lactic acid) blend. The high interaction between the components and the rapid evaporation of the solvent during electrospinning resulted in nanofibers with a lower degree of crystallinity in comparison with cast films. The electrical conductivity of the electrospun fiber mats was lower than that of blend films produced by casting, probably because of the lower degree of crystallinity of the polyaniline dispersion and the high porosity of the nonwoven mat. This novel system opens up new and interesting opportunities for applications in biomedical devices, biodegradable materials, and sensors, among other things. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Air permeability of electrospun polyacrylonitrile nanoweb

Ultrafine fibers were spun from polyacrylonitrile (PAN) solution in N,N‐dimethylformamide using a homemade electrospinning setup. Fibers with diameter ranging from 80 to 340 nm were obtained. Fiber size and fiber size distribution were investigated for various concentration, applied voltage, and tip‐to‐collector distance using image analysis. The diameters of the electrospun fibers increase when increasing the solution concentration and decrease slightly when increasing the voltage and needle tip‐to‐collector distance. Porosity and air permeability are vital properties in applications of electrospun nanofibrous structures. In this study, effects of process parameters on the porosity and air permeability of electrospun nanoweb were investigated as well. Results of statistical analysis showed that solution concentration and applied voltage have significant influences on pore diameters. It was concluded that nanofiber diameter played an important role on the diameter of pores formed by the intersections of nanofibers. A more realistic understanding of porosity was obtained and a quantitative relationship between nanoweb parameters and its air permeability was established by regression analysis. Two separate models were constructed for predicting air permeability in relation to process parameters. Optimization of electrospinning process for producing nanoweb with desirable air permeability is well achieved by these models. The models presented in this study are of high importance for their ability to predict the air permeability of PAN nanoweb both by process or structure parameters. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Abrasion resistance of thermoplastic polyurethane materials blended with ethylene–propylene–diene monomer rubber

The effect of ethylene–propylene–diene monomer rubber (EPDM) as an additive on the abrasion resistance of a thermoplastic polyurethane (TPU) resin was investigated. The mechanical properties and microstructure of the resultant TPU/EPDM composites were evaluated, and the surface morphology of the composites after abrasion testing was examined. The results showed that the addition of EPDM greatly improved both the mechanical properties and abrasion resistance of the TPU resin. A TPU/EPDM composite with 8 wt % EPDM demonstrated the highest tensile strength, the largest elongation at break, and the best overall performance. The abrasion of this composite was 27 mg, whereas that of the pure resin was 73 mg. With the further addition of EPDM, the abrasion resistance of the resultant composites decreased, whereas the viscosity increased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of vapor-grown carbon fibers from deoiled asphalt

Vapor-grown carbon fibers (VGCFs) with high-purity have been successfully prepared from the thermal cracking of deoiled asphalt (DOA) with ferrocene as catalyst by chemical vapor deposition (CVD) in argon atmosphere and characterized systematically by field-emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. Results showed that VGCFs with a diameter of 150-200 nm and a maximum length of 10-40 μm can be obtained.