Mechanical properties of denim fabric reinforced poly(lactic acid)

Denim, a twilled cotton fabric, was used to enhance the mechanical and thermal properties of poly(lactic acid) (PLA). The denim fabric reinforced composites with different numbers of denim layers were fabricated by using a hand layup method. The impact, tensile, and dynamic mechanical properties of the composites were observed with increasing denim layers to examine the reinforcing effect of denim fabrics. Numerical analysis was carried out to model the elastic modulus of the composite by using a commercial software. Three-dimensional geometry of the denim fabric reinforced PLA composite was generated through a CAD program, and the elastic modulus was calculated by applying uniform deformation on one surface. The impact strength, tensile strength, and thermal properties of the composites were improved by piling denim fabrics. The denim fabric reinforced composites exhibited outstanding impact strength due to the retarded crack propagation as well as large energy dissipation. The 3 layer denim reinforced composite showed best results among all specimens, and its impact strength, tensile strength, and tensile modulus were measured to be 82 J/m, 75.76 MPa, and 4.65 GPa, respectively. The PLA/denim composites have good mechanical properties and can substitute traditional composites such as glass fiber or carbon fiber reinforced composites.     

Mechanical anisotropy in unidirectional glass fabric reinforced oligomeric siloxane modified polyester composites

In this study, the effect of incorporation of oligomeric siloxane into unsaturated polyester on mechanical behavior of unidirectional glass fiber/polyester composites has been investigated by means of tensile, flexural and short beam shear tests. The amount of oligomeric siloxane added into unsaturated polyester was in the range 1?C3 % by weight of the glass fabrics. Mechanical tests were conducted at different angles (0 °, 45 °, and 90 °) with respect to fiber direction. The higher siloxane content exhibited a tendency to have greater tensile, flexural and interlaminar shear strength values in machine direction, bias direction and cross direction. From Scanning electron microscopy images, the presence of polyester particles on the unidirectional glass fiber surface confirmed better adhesion.     

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.     

Relationship between chemical composition,crystallinity, orientation and tensile strength of kenaf fiber

The physical properties of natural growth fibers such as chemical composition content and fiber diameter are highly affected by environmental issues such as environmental changes and fiber extraction methods. These irregularities of the natural fibers seriously affect its utilization in composite as reinforcements. In this study, taking into account the importance of the fiber tensile strength, the correlation degrees between the kenaf fiber tensile strength and the fiber chemical composition, crystallinity, orientation degree were analyzed by the grey relational analysis method. Both the kenaf single fiber and fiber bundle were used as XRD and tensile strength test sample. The chemical composition content and the FTIR were carried out to obtain a correct result of the chemical composition content. It found that for the different XRD and tensile strength test samples, the single fiber showed lower crystallinity, higher orientation degree and tensile strength compared with the fiber bundle. The cellulose content and the orientation degree got the higher correlation degree with single fiber tensile strength, which was 0.674 and 0.640. The highest factor associated with the fiber bundle tensile strength was the orientation degree, the correlation degree was 0.747. The hemicellulose content and the crystallinity also got high correlation degree with the fiber bundle strength, which was 0.687 and 0.640.     

Analysis and tensile characterization of air-entangled textured polyester woven fabrics depending on interlacement and yarn sets

The aim of this study was to understand the failure mechanism of two dimensional dry fabric structure considering yarn sets and interlacements. For this purpose, data generated on air-entangled textured polyester woven fabric under the simple tensile load and analyzed by developed regression model. The regression model showed that warp and weft directional tensile strengths of satin fabric were higher than those of plain and rib fabrics in unravel sample. This might be related to the number of interlacements of the fabrics. There was not a considerable difference between warp directional tensile strength of ravel and unravel satin fabrics, whereas weft directional tensile strength of ravel satin fabric decreased rapidly with respect to its unravel form. The satin fabric showed the highest warp directional tensile strength among the others. The lowest weft directional tensile strength was received from ribs fabric. In semi-ravel sample, all fabrics showed low warp and weft directional tensile strength values except in plain fabric. Warp directional tensile elongation of plain fabric was the highest in unravel sample. Satin fabric showed the highest warp directional tensile elongation in the ravel sample. Warp directional tensile elongations of all the fabrics in the semi-ravel sample became low. Weft directional tensile elongation of satin fabric was the highest in unravel sample. In addition, satin and plain fabrics showed the highest weft directional tensile elongations in the ravel sample. Weft directional tensile elongations of all the fabrics in the semi-ravel sample became low except in ribs fabric.     

Effect of mercerization on mechanical, thermal and degradation characteristics of jute fabric-reinforced polypropylene composites

Jute fabric reinforced polypropylene composites were fabricated by compression molding technique. Fiber content in the composites was optimized at 45 % by weight of fiber by evaluating the mechanical parameters such as tensile strength, tensile modulus, bending strength, bending modulus. Surface treatment of jute fabrics was carried out by mercerizing jute fabrics with aqueous solutions of NaOH (5, 10 and 20 %) at different soaking times (30, 60 and 90 mins) and temperatures (0, 30 and 70 °C). The effect of mercerization on weight and dimension of jute fabrics was studied. Mechanical properties of mercerized jute-PP composites were measured and found highest at 20 % NaOH at 0 °C for 60 min soaking time. Thermal analytical data from thermogravimetric and differential thermal analysis showed that mercerized jute-PP composite achieved higher thermal stability compared to PP, jute fabrics and control composite. Degradation characteristics of the composites were studied in soil, water and simulated weathering conditions. Water uptake of the composites was also investigated.     

Mechanical and water absorption properties of woven jute/banana hybrid composites

This work aims to predict the mechanical properties of woven jute/banana hybrid composite. Woven fabrics are arranged in three layers of different sequence. Resin used in this work is Epoxy LY556 with hardener HY951. Composite specimen are prepared by hand-layup techniques. The effect of layering sequence on the mechanical properties namely tensile, flexural and impact was analysed. It is found that the tensile and flexural strength of hybrid composite (Banana/Jute/Banana) is higher than that of individual composites. Similarly, the impact strength of Jute/Banana/Jute hybrid composite is better than other types of composite. It is found that the moisture absorption of woven banana fiber composite is lesser than the hybrid composite. Fractography study of the fractured specimen is carried out using scanning electron microscope to analyse the fracture behaviour of the hybrid composite.     

Development of superhydrophobic polyester fabrics using alkaline hydrolysis and coating with fluorinated polymers

Alkaline hydrolysis is one of the most classic fiber finishing methods, however, its potential as tuning surface superhydrophobicity in mass scale has not been studied much. In this research, fine roughness was formed on the polyester fiber surfaces by alkaline hydrolysis at room temperature and fluorinated polymer mixtures were further coated. The developed superhydrophobic fabrics were evaluated in terms of structural changes, mechanical properties, surface hydrophobicity, and permeability for practical applications. As alkaline hydrolysis treatment time increased, surface roughness was increased as a lot of nano-craters were generated with the decrease of fabrics weight and tensile strength as well. As air pockets formed through nano-craters on the fiber surfaces, static contact angle increased, and shedding angle tended to decrease. In this study, the sample treated with alkaline hydrolysis for 20 minutes showed the highest static contact angle of 167.8±1.3° and lowest shedding angle of 4.4±2.3°. Considering tensile strength loss, however, the 15-minute alkaline hydrolyzed fabrics which showed static contact angle of 162.2±2.7° and shedding angle of 8.8±0.2° was selected as the optimal condition for practical application. The newly developed superhydrophobic fabrics were found to have higher water vapor and air permeability than those of untreated samples. At the same time, fluoropolymer coating played a certain role for tensile strength and water vapor permeability demonstrating the importance of understanding and designing proper fluorinated-compound treatment processes.     

A study on mechanical,thermal and environmental degradation characteristics of N,N-dimethylaniline treated jute fabric-reinforced polypropylene composites

The mechanical and thermal behavior of compression molded jute/polypropylene (PP) composites were studied by evaluating tensile strength (TS), bending strength (BS), tensile modulus (TM), bending modulus (BM), impact strength (IS), thermogravimetric (TG/DTG) and differential thermal analysis (DTA). A chemical modification was made to jute fabrics using N,N-Dimethylaniline (DMA) in order to improve the interfacial adhesion between the fabrics and matrix. It was found that jute fabrics on treatment with N,N-Dimethylaniline (DMA) significantly improved the mechanical properties of the composites. Thermal analytical data of PP, both treated and untreated jute fabrics as well as composites revealed that DMA treatment increased the thermal stability of the fabrics and composite. DMA treatment also reduced the hydrophilic nature of the composite. DMA treated jute composite was found less degradable than control composite under water, soil and simulated weathering conditions.     

Moisture absorption effect on thermal, dynamic mechanical and mechanical properties of injection-molded short glass-fiber/polyamide 6,6 composites

Polymer composites of polyamide 6,6 reinforced with short glass fiber were prepared by injection molding, conditioned under dry, 50 % relative humidity and wet. Investigations by DSC, DMA and tensile tests were conducted. FLD study showed that more fiber degradation occurred during processing of the composites with higher fiber loading. DSC analysis revealed that the incorporation of glass fiber and moisture into the PA 6,6 matrix resulted in a remarkable decrease in the degree of crystallinity. DMA results revealed the glass transition temperatures were sensitive to moisture absorption and their values moved to a lower temperature upon exposure to moisture. Incorporation of glass fiber into the polyamide 6,6 gave rise to a significant improvement in tensile modulus and tensile strength, while tensile strain was reduced. Exposure to different environments from dry to wet conditions resulted in a decrease in the strength and modulus, while tensile strains decreased.     

Effect of polypropylene fiber cross sectional shapes on some structural/mechanical fiber properties and compressibility behaviour of plain knitted fabrics

Synthetic fibers are generally produced with circular cross sectional shapes. Other cross sectional shaped fibers such as trilobal, triangular, hollow and pentagonal fibers are also produced to improve some properties of fibers and fabrics such as lustre, handle, wicking rate, strength, stiffness and bulkiness. In this research we aimed to investigate compressional behaviours of fabrics knitted from polypropylene fibers having three different cross sectional shapes; namely circular, trilobal and triangular. Morphological, structural and mechanical properties of produced fibers were evaluated by using scanning electron microscopy, X-ray diffractometry, differential scanning calorimetry and tensile tester, respectively. In terms of structural and mechanical properties, no significant differences were found related to fiber cross sectional shapes. Then, plain knitted farbrics were produced and compressional properties of these fabrics were investigated. Fabrics knitted from trilobal fibers showed the highest compressibility properties and it is followed by fabrics which are produced from triangular and circular fibers.     

Fabrication of novel multifunctional hybrid materials for PET/PA6 nonwoven fabrics finishing

A series of some novel hybrid materials prepared via a sol-gel process have been synthesized from methyltrimethoxysilane and titanium n-butoxide with heterocyclic thiazole azo dyes. Silica/titania/thiazole azo dyes hybrid materials were synthesized via a sol-gel process with a precursor system. Alternatively, the heterocyclic thiazole azo dyes were catalytically processed by means of hydrolysis-condensation reactions with appropriate amounts of a mixture of vinyltriethoxysilane, methyltrimethoxysilane, and titanium n-butoxide at a fixed molar ratio. The structure of these hybrid silica/titania/thiazole dye materials was characterized by Fourier transform infrared (FT-IR) analysis. The surface morphology of processed PET/PA6 nonwoven fabrics was evaluated by scanning electron microscopy (SEM). SEM images showed uniform dyeing, thereby confirming the reaction of the hybrid materials with the PET/PA6 nonwoven fabrics. The water contact angle, washing fastness, color evenness, air permeability, and weatherability characteristics of the as-prepared dyed PET/PA6 nonwoven fabrics were subsequently evaluated. Results revealed improved weatherability and good water repellency. Further, it was also revealed that dyeing and finishing could be achieved in a single bath, which is advantageous to reduce processing costs.     

A new catalyst for glyoxal durable press finish of cotton fabrics

Aluminum ammonium sulfate was used as a new catalyst for glyoxal to minimize the decrease of physical properties of durable press cotton fabrics, and the optimum treatment conditions such as the concentration of glyoxal, molar ratio of catalyst to glyoxal, curing temperature and time were investigated. The retention of tensile strength and the whiteness of fabrics treated with glyoxal/aluminum ammonium sulfate was increased as much as to the degree of that obtained with glyoxal/aluminum sulfate while wrinkle recovery angles were as good as those of the latter. Some additives such as DEG, polyurethane and softener were used to improve the physical properties. When DEG or polyurethane was added to the glyoxal padding solution, wrinkle recovery angle (WRA) significantly increased while tensile strength and whiteness were not influenced. DEG added to the glyoxal padding solution increased the durability of DP finish. The softener added to the glyoxal padding solution increased the WRA of treated fabrics while it decreased the tensile strength slightly. The whiteness of fabrics treated with glyoxal alone increased while the WRA decreased slightly.     

Surface modification of polyester fabrics by enzyme treatment

In this study, the effect of enzymatic hydrolysis using lipase and cutinase on poly(ethyleneterephthalate) (PET) fabrics was investigated in an attempt to improve the hydrophilicity of these fabrics. The hydrolytic activity of the enzymes was expressed for variations in pH levels, temperatures, enzyme concentrations, and treatment times. The effects of using a nonionic surfactant were examined by measuring moisture regain and surface wettability. Finally, the fabric characteristics that were affected by enzyme treatment were evaluated by tensile strength and scanning electron microscopy. The optimal treatment conditions for lipase were determined to be a pH of 4.2, a temperature of 50 °C, a lipase concentration of 100 %, and a treatment time of 90 min; those for cutinase were determined to be a pH of 9.0, a temperature of 50 °C, a cutinase concentration of 100 %, and a treatment time of 60 min. At optimal enzymatic treatment conditions, we got the significant results of increase on the moisture regain and the water contact angle (WCA) and water absorbency effectively decreased. Triton X-100 facilitated cutinase hydrolysis on PET fabrics; however, it was ineffective for lipase. With enzymatic treatment, the tensile strength did not decrease.     

Dimensional,physical and thermal properties of plain knitted fabrics made from 50/50 blend of modal viscose fiber in microfiber form with cotton fiber

In this study, the dimensional, physical and thermal comfort properties of the plain knitted fabrics made from 50/50 blend of modal viscose fiber in microfiber form with cotton fiber are compared with those of the similar fabrics made from 50/50 blend of conventional modal viscose fiber with cotton fiber and made from 100 % cotton fiber. All the fabric types are produced in three different stitch lengths. The slight differences among the fabric types are observed in terms of the stitch density results and the dimensional constants calculated in the fully relaxed state. In the fully relaxed state, the dimensional K values of the modal microfiber blended knitted fabrics are found to be more closely resemble those of the cotton fabrics rather than those of the conventional modal fiber blended fabrics. The lowest fabric thickness and bursting strength results are obtained for the modal microfiber blended fabrics. The modal microfiber blended fabrics reveal lower air permeability than the conventional modal fiber blended fabrics and higher air permeability than the cotton fabrics. It is also observed from the thermal comfort results that the modal microfiber blended fabrics have the lowest thermal resistance and the highest thermal absoptivity values. The thermal conductivity results of the modal microfiber blended fabrics are lower than those of the cotton fabrics and higher than those of the conventional modal fiber blended fabrics. Because of the highest thermal absorptivity values, the modal microfiber blended fabrics provide the coolest feeling when compared with the other two fabric types.     

Lipase treatment of polyester fabrics

The aim of this paper is to improve moisture regain of PET fabrics using a lipase treatment. Effects of nine lipase sources, lipase activator and nonionic surfactant on moisture regain of PET fabrics are examined. Moisture regains of lipase-treated samples improve by two times in average compared with untreated and buffer-treated samples. Alkaline treatment creates larger pitting by more aggressive attack into fiber which is proved by SEM and water contact angle measurement. Moisture regain by alkaline treatment (0.568 % ± 0.08) does not improve. However, lipase-treatment (L2 treatment) improves moisture regain up to 2.4 times (1.272 % ± 0.05). Although lipase treatment is more moderate than alkaline treatment, lipase hydrolysis on PET fabrics improves moisture regain, efficiently. K/S values improved confirm that carboxyl and hydroxyl groups are produced on the surface of PET fabrics by lipase hydrolysis. Moisture regain and dyeability improve by lipase hydrolysis on PET fabrics.     

Study of moisture and thermal transfer properties as a function of the fiber material variation

The properties of moisture transfer and the comfort of mesh-structured fabrics with various knit compositions and properties were investigated. The comfort effects of the double knitted fabrics combined with different cross-shaped fibers composed of dyeable-polypropylene (PPd) and regular polyester (PET) double-knitted fabrics were studied. A series of PET, PPd, Coolmax^® (Cm) with single knitted fabrics and PPd/Cm with double knitted fabrics were evaluated to determine the physical properties and wearing performance for comfortable clothing. To compare the structural properties involving the vapor transfer of 4 types of fabrics with different fiber compositions, fiber types, weights, and thicknesses, the surface structure and pore characteristics were evaluated by scanning electron microscopy and a capillary flow porometer. The properties of moisture transfer were tested using vertical wicking and gravimetric absorbent testing system (GATS). In addition, the comfort performance measured by the thermal insulation value (Rt) and moisture permeability index (im) with a thermal manikin in a conditioned walk-in environmental test chamber was predicted. The result showed that the PPd/Cm sample has potential applications as good comfort fabric materials.     

Analysis and off-axis tensile characterization of air-entangled textured polyester woven fabrics depending on unit cell interlacing frequency

The aim of this study is to analyze and determine the off-axis tensile properties of air-entangled textured polyester fabrics based on unit cell interlacing frequency. For this purpose, continuous filament polyester air-entangled textured yarn was used to produce plain, ribs and satin woven fabrics. The fabrics were cut from the warp direction (0°) to weft direction (90°) at every 15° increment, and tensile tests were applied to those of the off-axis samples. The strength and elongation results were introduced to the statistical model developed, and regression analyses were carried out. Hence, the effects of off-axis loading and interlacement on the directional tensile properties of the fabric were investigated. The regression model showed that off-axis loading influences fabric tensile strength. On the other hand, interlacement frequency is the most important factor for fabric tensile elongation. The results from the regression model were compared with the measured values. This study confirmed that the method used in this study as can be a viable and reliable tool. Future research will concentrate on multiaxially directional fabric and the probability that it will result in homogeneous in-plane fabric properties.     

Development of moisture transition ability on porous complex structured woven fabric with convergence of pattern,porosity, and plasma technology

A porous complex structured woven fabric was manufactured to maximize the moisture transition ability of the prepared fabric by increasing the absorptive property of the fabric through surface modification using plasma, which is a dry modification method. Porous single and complex structured woven fabrics were produced by applying pattern, porosity, and plasma technology, including fabric patterning based on the sheath/core complex structure, the formation of porosity by removing the weft thread or warp thread, and hydrophilic surface treatment using plasma and the improvement in water absorption of different fabrics by the porous and plasma treatment was investigated. Therefore, two different types of fabrics were prepared. One is the porous single structured FAB-SINGLE fabric which was taken out in the direction of the Polyester (PET) warp thread of a general single structure to form a porous. Another is FAB-COMPLEX fabrics that the water-soluble polylactic acid (PLA) yarns with a 1.7 to 2.0 times longer absorption distance than that of PET yarns were inserted into the weft threads, and the PLA yarns were dissolved in a solvent to form the porous complex fabric. And then the physical properties and water absorption of the two types of fabric were compared after the plasma treatment. The results showed that when the FAB-SINGLE fabric, which has porosity induced by the removal of the warp threads in a certain gap, was plasma treated for 5 min, the contact angle was decreased to the extent that a measurement of the contact angle was impossible, whereas the fabric that had not undergone a plasma treatment had a contact angle of 123.6 o. The contact angle of the FABCOMPLEX with porosity caused by the dissolution of the PLA yarns was reduced from 76.8 o to 0 o after 3 minutes of a lowtemperature plasma treatment, indicating that the hydrophilic property was increased. In addition, the water absorption measurements showed that the absorption height was increased from 2.3 cm of the fabric sample that had not been treated with plasma to the highest absorption height of 8.3 cm, suggesting that the water absorption also increased with the improvements in moisture transition ability by the plasma treatment. The physical tensile strength of the fabrics was not changed by the plasma treatment, despite the changes on the fabric surface, suggesting that the combination of double complex structures and the plasma treatment helped improve the water absorption.     

A study of physical modification on grey cotton by laser irradiation

The surface morphology of the CO₂ laser treated grey cotton fabrics was studied which showed a characteristics sponge-like structure on cotton fibres after treating with CO₂ laser irradiation. The laser treatment parameters ranging from 100 to 150 pixel time and 40 to 70 dot per inch (dpi) were irradiated on the grey cotton fabrics directly and the degree of physical modifications, such as surface morphology, wettability and fabric strength, were changed accordingly with various laser treatment parameters. The surface morphology, wettability and tensile strength of cotton fibre treating with laser were evaluated using different instruments, such as Scanning Electron Microscope (SEM), contact angle meter and tensile strength machine. In spite of creating a sponge-like structure on fibre surface after treating with laser, the wettability of the samples was highly improved but the tensile strength was decreased.