Increase In Tenacity Research Articles

PVA/titanate nanotube nanocomposites: Evaluating the required structural properties for their performance as macromolecule delivery systems

AbstractBiopolymer‐based nanocomposites are gaining prominence in the fabrication of biomedical devices, with polyvinyl alcohol (PVA) being widely used in smart dressings for drug and protein integration. This study introduces electrospun mats composed of partially hydrolyzed PVA and sodium titanate nanotubes (TiNTs). The investigation involved mats with TiNT concentrations ranging from 0% to 5% at room temperature. The morphological and structural changes resulting from adding TiNTs were examined in detail. The inclusion of TiNTs impacted parameters such as mean fiber diameter (130–190 nm), crystallinity degree (30–50%), and porosity (70–55%) and was closely associated with the viscoelastic properties of the mats. Higher TiNT concentrations led to reductions in either the storage modulus, from 350 to 220 MPa, or in the loss modulus, from 30 to 25 MPa, unveiling an increase in tenacity. Furthermore, in vitro release tests were conducted using bovine serum albumin (BSA) in Franz cells over 48 h. The results indicated that release profiles were best fitted by the Higuchi model (0.95 > R2 > 0.99) for both PVA mats (0% and 5.0% TiNTs), with the 5% TiNTs‐PVA membrane demonstrating greater BSA diffusion when compared to pure PVA. The release constant 𝐾rel, representing the rate of drug diffusion, was found to be 0.006 for 5% TiNT‐PVA mats and 0.002 μg h‐1/2 for pure PVA, respectively. These results suggest the potential of these materials in designing controlled transdermal delivery systems that could significantly improve the efficacy and safety of drug applications.

Fortifying wheat bread with whey proteins: impact on nutritional value and technological properties

Wheat bread is a widely consumed commodity around the world. It is poor and imbalanced in some essential amino acids. The aim of this study is to fortify wheat bread with whey proteins (WP), in order to inhence its nutri-tional value and to improve the balance of its essential amino acids. The composition of the different flours and breads enriched with WP was deter-mined by standard methods. The alveograph’s results show that the tenacity increases and the deformation energy decreases with increasing incorpora-tion of WP. The addition of WP leads to a dough that is resistant to defor-mation, extensible for incorporation rates of 2.5% and 3% and less extensible for 10% and 20%. The results on the composition of the different breads show that the addition of WP contributes to the improvement of the amino acid profiles of the breads, especially for P10 and P20. It corrects, especially, the deficit and imbalance of the bread in essential amino acids. The assess-ments of the organoleptic characteristics show that the majority of the tast-ers find the P2.5 and P3 breads are very close to the commercial breads and sometimes better. These loaves have a nice external appearance, regular shape, crispy golden crust, light texture, good taste and smell. The develop-ment of the breads during vacuum storage is very satisfactory. They keep their crispness and a good crumbliness after 7 days.

Pseudoboehmite or graphene oxide, what is the best additive for natural polymer pla—poly (l-lactic acid)?

In cases of severe injuries or burns, skin grafts (scaffold) are often necessary skin substitutes. To not harm the patient or the donor, research is necessary to search for heterografts, that are formed by biomaterials and are also biodegradable and bioabsorbable to the human body, as is the case with poly (L-lactic acid) - PLA. However, the natural polymers placed on the skin suffer great degradation in media with large amounts of carbon and water, have little durability due to their low ductility. For the proposal, the graphene oxide (GO) nanocharge and pseudoboehmite (PB) were obtained. It is believed that the nanofillers dispersed in the polymer matrix can improve mechanical properties regarding ductility and tenacity, without losing thermal properties. Subsequently, the hybrid nanocharge dispersion methods were employed to obtain in the poly (L-Lactic Acid) (PLA) matrix, forming the material for the desired scaffold. For this research, injectable specimens of pure PLA, PLA structured with GO nanoparticles, and PLA structured with PB nanoparticles, were manufactured. The microstructural and mechanical characterizations were performed on the specimens, to compare the effect generated by the nanocharges on the bulk material. The results showed that the increase in the concentrations of PB and GO nanofillers showed an increase in tenacity and ductility compared to pure PLA, a property that is desired in the scaffold structure.

Chemical treatment of nettle ribbons and its effect on tensile property of extracted fiber

Stinging nettle (Girardinia diversifolia) is a cellulosic plant fiber which is abundantly available in the upper regions of Himalayas. The stem fibres are pliable which are used to weave or knit fabric. This fiber is very strong, but rigid and inextensible. This has restricted its usage in handmade textile products only. In order to process this fiber on a range of textile machines for development of a variety of products with enhanced performance, the fiber needs to be strong, flexible and extensible. This study was aimed at to increase the fiber tenacity by giving chemical pre-treatment. The effects of various experimental parameters, such as chemical concentration and time on tenacity of nettle fibres were studied. In the study, the chemical pre-treated nettle fibers were examined for their mechanical characteristics and compared to untreated fibers (control sample). The untreated fiber was less flexible and less extensible. A pre-treatment resulted in increase in tenacity and elongation at break. The increase in tensile strength was found to be 5.46 g/den from 3.84 g/den (as in case of control sample) and elongation increased to 3.33% from 1.66%.

New Brazilian pineapple leaf fibers for textile application: cottonization and dyeing performance

This work evaluates the dyeing performance associated with a cottonization and bleaching pretreatment of pineapple leaf fibers from two different species from Brazil: curaua (A. lucidus syn. A. erectifolius) and red pineapple (A. bracteatus (Lindl.) Schult. & Schult.f), aiming its application in textile materials for garments. Treated and untreated fibers were compared for their morphological, chemical, physical and color properties. The fibers underwent changes in their chemical and physical structural characteristics after pretreatment. The results of SEM, FTIR and whiteness index analysis indicated that the cottonization process improved the color and surface uniformity of fibers, reducing non-cellulosic matters, such as lignin and pectin. Treated fibers also presented low impurities content, i.e., oils, wax and fats (between 1.1 and 2.1%). However, compared to untreated fibers, treated curaua show an increase in impurities, supposedly caused by the removal of epidermal tissue from the fiber surface, which became the fiber bundle structure more accessible. Cottonization process also produced thinner, individualized and more resistant fiber bundles, which was evidenced by a decrease in linear density by 30 and 42% and an increase in tenacity by 12 and 23%. The dyeing behavior of fibers was investigated using blue, red and yellow reactive dyes. Fibers of both species demonstrated good dyeing behavior, with K/S values compatible with textile application standards (between 4 and 11) and an excellent color fastness to laundering.

Novel Methods of Degumming and Bleaching of Indian Flax Variety Tiara

ABSTRACT Tiara is the only fiber variety flax recently been introduced in India. The water retted flax fibers were mechanically extracted and subjected to degum and bleach using various chemicals and enzymes and the treatment conditions were optimized. The tenacity and elongation of the fiber were found to be improved when ethylene diamine tetra acetate (EDTA) was used to degum the fiber before peroxide bleaching. The effect of hydrogen peroxide in flax bleaching was studied at different mediums. Oxalic acid and EDTA assisted peroxide bleaching shows 23% and 50% increase in tenacity and whiteness as compared to raw fiber. The characterization of fiber done through FTIR, SEM, and analysis of chemical composition, shows the removal of pectin and hemicellulose from the fiber as a result of chemical treatments.

Effect of surface treatment of natural reinforcement on thermal and mechanical properties of vinyl ester/polyurethane interpenetrating polymer network-based biocomposites

Kenaf fibre-reinforced vinyl ester (VE)/polyurethane (PU) interpenetrating polymer network (IPN)-based composites were made by hand lay-up technique. The kenaf bast fibre was chemically treated with 3, 6 and 9% vinyl silane. Treated fibres were characterized in terms of crystallinity, mechanical strength, density, thermal property and morphology. In comparison with the untreated fibre, 6% silane-treated fibres showed 25.4% higher % crystallinity, 66.9% increase in modulus elasticity and 604.2% increase in tenacity. Comparison of the pure VE with VE/PU IPN showed that the IPN had 3.3% lower modulus but 26.4% higher toughness than the former. Composites based on pure VE matrix and VE/PU IPN matrix were manufactured with the variation of untreated and treated fibre loading as 15, 20, 25, 30, 35 and 40 wt%. Novelty of this work lies in the modification of both the fibre surface and the matrix system simultaneously with the aim of increasing the adhesion between the fibre surface and matrix material of the composite. Composites with untreated fibres showed poor strength compared to that with modified fibres having corresponding compositions. IPN-based composites, with 35 wt% silane-treated fibre, showed improvement in tensile modulus by 16.61% and flexural modulus by 6.35% than pure VE-based composites with corresponding fibre loading.

Increased wave action promotes muscle performance but increasing temperatures cause a tenacity-endurance trade-off in intertidal snails (Nerita atramentosa).

Concurrent increases in wave action and sea surface temperatures increase the physical impact on intertidal organisms and affect their physiological capacity to respond to that impact. Our aim was to determine whether wave exposure altered muscle function in intertidal snails (Nerita atramentosa) and whether responses to wave action and temperature are plastic, leading to compensation for altered environmental conditions. We show that field snails from exposed shores had greater endurance and vertical tenacity than snails from matched protected shores (n = 5 pairs of shores). There were no differences in muscle metabolic capacities (strombine/lactate dehydrogenase, citrate synthase and cytochrome c oxidase activities) between shore types. Maximum stress (force/foot area) produced by isolated foot muscle did not differ between shore types, but foot muscle from snails on exposed shores had greater endurance. A laboratory experiment showed that vertical tenacity was greater in animals acclimated for 3 weeks to cool winter temperatures (15C) compared to summer temperatures (25C), but endurance was greater in snails acclimated to 25°C. Acclimation to water flow that mimicked wave action in the field increased vertical tenacity but decreased endurance. Our data show that increased wave action elicits a training effect on muscle, but that increasing sea surface temperature can cause a trade-off between tenacity and endurance. Ocean warming would negate the beneficial increase in tenacity that could render snails more resistant to acute impacts of wave action, while promoting longer term resistance to dislodgment by waves.

Structure–Property Evolution of Poly(ethylene terephthalate) Fibers in Industrialized Process under Complex Coupling of Stress and Temperature Field

The structure–property evolution of commercial poly(ethylene terephthalate) (PET) fibers obtained from the different drawing and heat-setting stages in industrial processing was systematically investigated. Upon combination of thermal analysis (DSC and DMA) with crystallization and orientation (WAXD and SAXS), the variation of crystallization and microstructures mainly containing lamellar and microfibrillar crystals following the processes were discussed in connection with properties. Results indicate the significant tenacity increase of fiber in the drawing process is mainly attributed to the orientation development of the interlamellar amorphous region, the interfibrillar extension of amorphous molecular chains, and its entanglement with the lamellae. Accordingly, a decline of shrinkage can be seen as a fact of the coiling of amorphous molecular chains, the formation of rigid amorphous fraction, and the increase of crystallinity. Thus, a new four-phase model has been proposed to clarify the structure–pr...

Analysis of Mechanical and Micro-Structural Properties of Shaft Tips Manufactured in ABNT 1045 Steel Applied in Transportation Ore Fractured Early

This paper aims is the study of shaft tips applied in ore transportation that are subjected to continuous torsional stresses, and which rupture early. This component consists of an ABNT 1045 steel shaft, where an ABNT 1020 steel flange is welded by the MIG/MAG (GMAW) process, both fixed, in addition to welding, by ABNT 1020 steel latches welded to the flange and shaft. The methodology is based on fracture analysis of the material and application of thermal treatments at different temperatures in order to reduce the incidence of early fracture. The results showed that the thermal treatment at 300oC for 4 hours was the most efficient in all regions, giving the shaft an increase of tenacity, without losing its mechanical resistance and hardness, indispensable properties to the shafts taking into account its characteristics operation.

Structural analysis of Ioncell-F fibres from birch wood

Quite recently, the Ioncell-F process, a novel and promising Lyocell fibre process, has been developed. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) utilized in this process, was identified as an excellent cellulose solvent for dry-jet wet fibre spinning. Fibres spun from cellulose-[DBNH]OAc solution have shown excellent mechanical properties. Herein, various structural features of these ionic liquid-based fibres were analyzed and correlated with their mechanical properties. The highest slope of tenacity increase of these Ioncell-F fibres (from birch wood) observed at low draw ratios (DRs), while a continuous but slower increase occurs to partly very high draws. The improvements in the mechanical properties do not seem to correlate with changes in the crystallite size or the crystalline orientation based on wide-angle X-ray scattering (WAXS) results. More significant differences were seen for the sample crystallinity, the amorphous orientation (measured by birefringence), the orientation of the voids, the specific surface (measured by small-angle X-ray scattering (SAXS)), and the sorption/desorption properties of the fibres.

Research on High Speed Machining of TC17 Titanium Alloy Under Extreme Environments

In this paper, high-speed cutting experiment has been carried out on TC17 titanium alloy after secondary ageing treatment in extreme environments, − 60 and 300 °C respectively. Hyperfocal 3D microscopic system has been adopted to analyze the cutting surface morphology; TEM microstructure analysis has been carried out on TC17 titanium alloy before and after cutting, and the cutting tool’s frictional wear and surface quality have been studied after cutting TC17 titanium alloy in extreme environments. The results show that: the cutting tool mainly displays abrasive wear at − 60 °C with chipping problems, while at 300 °C the cutting tool mainly displays oxidative wear and adhesive wear; at − 60 °C, the hardness and brittleness of TC17 titanium alloy increases after subzero treatment, and the cutting produces poor surface quality; at 300 °C, both the hardness and brittleness of the alloy decreases after regressive heat treatment, but the tenacity increases. During the cutting, oxide film is generated on a constant basis, thus the surface quality gets significantly enhanced, and the cutter life lengthened; at − 60 °C, the dispersed phase of the material gets finer, while at 300 °C, the dispersed phase disappears considerably, or rather, regression takes place.

Property of ramie fiber degummed with Fenton reagent

This paper investigated the performance and morphology of ramie fibers degummed using Fenton reagent. In order to deeply understand the reaction characteristics, SEM, XRD and FT-IR were employed to characterize the morphologies, chemical components and crystallinity of degummed fibers. Also, the physical and mechanical properties such as tenacity, breaking elongation, density, softness and degree of polymerization of degummed fibers were measured. The experimental results indicated that Fenton can serve as an effective oxidation degumming agent under weak acid condition. The new degumming method could remove more gummy components from raw ramie, whereas the cellulose content in treated fibers was further increased compared with the alkaline oxidation degumming. The fibers degummed using Fenton showed slight increase in tenacity and significant increase in density as well as breaking elongation comparing with alkaline oxidation degumming. The degummed fibers were also characterized in terms of SEM, XRD and FTIR which confirmed the effectiveness of the new degumming method.

Mechanical and ballistic analysis of aramid/vinyl ester composites

This study focused on evaluating mechanical and dynamic-mechanical properties of polyaramid/vinyl ester composites, as a function of the fiber content. Furthermore, split Hopkinson pressure bar technique and V50 Ballistic limit tests were performed. Composites were prepared by resin transfer molding (RTM) with different fiber content, samples being identified as AD4, AD5 and AD6 (with 4, 5 and 6 polyaramid layers, respectively). Initially, fiber, void and matrix contents were calculated and statistically analyzed, in different regions of the composites. Mechanical and dynamical mechanical properties of the composites were improved by using higher fiber content. For example, impact strength of AD6 composite was 35% higher than AD4. Moreover, increase in the fiber content promoted an increase in tenacity and stress of the composites, in the same strain rate. Velocity limit in AD6 sample was estimated in ballistics tests and it was concluded that the composite obtained could accomplish the level I requisites of ballistic protection with V50 of 304 m.s−1.

Influence of Spindle Air Pressure and its Direction on the Quality Characteristics of Polyester/Cotton Vortex Yarn

The influence of spindle air pressure and its direction on the properties of Polyester/Cotton vortex yarn was studied. The spindle air pressure direction was changed in both Z and S directions on the Z twist yarn of Ne 40s Polyester/Cotton vortex yarn (50:50 polyester: cotton) and these yarns were then tested for their properties such as tensile, unevenness, and hairiness. It was found that unevenness was lower with normal spinning condition and increased when the spindle air pressure increased in both directions. Imperfections were also found to be minimum with normal spinning condition and increased with increase in spindle air pressure. The yarn tenacity and elongation at break found to be lower at normal spinning condition. When the spindle air pressure increased yarn tenacity and elongation at break also increased with increase in spindle air pressure. At the same time spindle air pressure in the same direction of basic yarn twist gave less increase in tenacity and elongation than opposite direction of basic yarn twist. Hairiness index, H and hairiness in different length classes continuously increased as the spindle air pressure increased in opposite direction of basic yarn twist.

Vliv redukčních a oxidačních činidel na reologii pšeničného těsta

The effects of a reducing agent (L-cysteine hydrochloride monohydrate), oxidising agents (ina­cti­va­ted dry yeast, L-tyrosine) and other two amino acids (L-threonine and L-tryptophan) on the rheological characteristics of wheat flour dough and its quality were studied. The addition of oxidising agents increases the values such as tenacity and decreases extensibility which were measured on the alveograph. From the consistograph values, weakening of the dough also decreases. While reducing agents increase the extensibility and weakening of the dough, they decrease its deformation energy. The addition of L-tryptophan caused a higher increase in tenacity of the dough but on the other hand a larger decrease in extensibility and deformation energy. L-tryptophan caused better stability of the dough. L-treonine was found to be an oxidising agent. The dough with L-threonine weakened rapidly and therefore fast preparation of the dough is necessary. It means that the time of mixing and dough proo­fing must be reduced.

Effect of preswelling and ultrasound treatment on the properties of flax fibers cross-linked with polycarboxylic acids

This paper presents the investigation of sorption and mechanical properties of single flax fibers (fiber bundle) cross-linked with polycarboxylic acids (PCA; citric acid [CA] and 1, 2, 3, 4-butanetetracarboxylic acid [BTCA]). The improvement of the chemical modification performance was carried out by pre-treating of the fibers with sodium hydroxide and ultrasound (US). Thus, the purpose of the investigations was to determine whether the sorption and mechanical properties of the cross-linked fibers would be enhanced by a preswelling and US treatment before the application of PCA. The effect of cross-linking PCA with cellulose molecules on flax fiber properties was determined by measuring and comparing the properties (fineness, tenacity, and elongation at break; breaking twist; moisture absorption; and water-retention value) of untreated and modified flax fibers. The test results indicate that treatment with PCA undoubtedly changes the tested properties: water retention values decrease while the resistance to tenacity increases. The observed changes are the result of structural alterations in fibers. Fourier-transform infrared (FT-IR) spectra confirmed that cross-linking between the carboxyl groups of acids and the hydroxyl groups of cellulose occurs due to the esterification reaction. Preswelling and US treatments have increased the accessibility of cellulose in flax fibers, and cross-linking was achieved with less fiber damage, whereby US proved to be a more successful pre-treatment.

Effect of Jet Stretch and Particle Load on Cellulose Nanocrystal−Alginate Nanocomposite Fibers

Alginate fibers have found many applications such as the preparation of dressings to treat exuding wounds, drug delivery, enzyme immobilization, etc.; however, their use is limited due to poor mechanical properties. Cellulose nanocrystals (CNCs) were isolated from cotton and introduced into calcium alginate fibers with the goal of improving their strength and modulus. The isolated CNCs are elongated nanoparticles of crystalline cellulose with an average length of 130 nm with a standard deviation (s) of 63 nm, an average width of 20.4 nm (s = 7.8 nm), and an average height of 6.8 nm (s = 3.3 nm). The CNCs were mixed with an aqueous sodium alginate dope solution and wet spun into a CaCl(2) bath to form fibers. It was found that if the apparent jet stretch (ratio of the fiber draw velocity to extrusion velocity) is kept constant, addition of the nanocrystals reduces the tensile strength and modulus of the material; however, a small concentration of CNCs in the dope solution increases the tensile energy to break and enables an increase in the fiber spinning apparent jet stretch ratio by nearly 2-fold at up to 25% CNCs load; the maximum ratio of 4.6 is observed at 25 wt % CNC loading as compared to a maximum of 2.4 for the native alginate. Mechanical testing showed a 38% increase in tenacity and a 123% increase in tensile modulus with 10 wt % CNCs loading and an apparent jet stretch of 4.2. The data suggest that alignment of the nanocrystals in the composites is a key factor influencing the mechanical properties. CNCs have potential to become a biocompatible, renewable, and cost-effective solution to reinforce alginate fibers.

Cladodes from Opuntia ficus indica as a source of dietary fiber: Effect on dough characteristics and cake making

Chemical composition and physical properties of Mediterranean (Tunisian) spiny ( Opuntia ficus indica f. amylocea) and spineless cladodes ( O. ficus indica f. inermis) were studied. Chemical characterization of the two cladodes varieties showed a high fiber, minerals, especially potassium and calcium, and phenols contents. Powders obtained from spiny and spineless cladodes showed a great technological potentiality as water binding capacity (WBC) and fat absorption capacity (FAC). Cladodes powders were incorporated in wheat flours at 5%, 10%, 15% and 20% levels. Obtained results showed that cladodes flours had a significant effect in wheat dough properties ( P < 0.05). In deed, with the increase of cladodes flours levels, an increase of tenacity, energy, adhesion, stickiness, and hardness of dough was observed whereas dough elasticity decreased. A significant difference in physical characteristic between cakes fortified with cladodes flours and control was showed ( P < 0.05). With the increase of cladodes flours levels in formulation, cakes hardness increased whereas L * and a * crust and crumb color values decreased. Increasing levels of cladodes flours caused decreases in total sensory scores. The overall acceptability rate showed that a maximum of 5% cladodes flours can be incorporated to prepare acceptable quality cakes.

Processing and Properties of Nanocomposite Filament Yarns with Various Filler Concentrations from Two Different Modification Methods

AbstractIn this research, the possibility of producing and processing nanocomposite polypropylene filament yarns with permanent antimicrobial efficiency has been assessed by comparing two different methods. Therefore two approaches were used to mix various blending contents of antimicrobial agents based on silver/TiO2 nano particles with PP: 1) mixing of PP powder and inorganic nanocomposite powder as an antibacterial agent with the appropriate concentration in a twin screw extruder, preparing modified granules and feeding them to the melt spinning machine, 2) producing masterbatch by a twin screw extruder and blending it with PP in the melt spinning process. In both methods, pure PP and all other combined samples had an acceptable spinnability at the spinning temperature of 240 °C and take‐up speed of 2000 m/min. After producing as‐spun filament yarns by a pilot plant melt spinning machine, samples were drawn, textured and finally weft knitted. Physical and structural properties of as‐spun and drawn yarns with constant and variable draw ratios were investigated and compared. Moreover, the DSC, SEM and FTIR techniques have been used for samples characterization. Finally antibacterial efficiency of knitted samples was evaluated. The experimental results indicated that the maximum crystallinity reduction of modified as‐spun yarns reached 5%. But by applying method 2 (masterbatch), crystallinity of modified as‐spun yarns remained unchanged compared to pure yarn. However, drawing procedure has compensated this difference. By applying the second method, the drawing generally improved the increase of tenacity and modulus of modified fibers, whereas in method 1 the opposite effect was noticed in the case of constant draw ratio. Although the biostatic efficiency of nanocomposite fibers was excellent in both methods, modified fabrics obtained from method 1 showed higher bioactivity.