Liquid handling properties of hollow viscose rayon/super absorbent fibers nonwovens for reusable incontinence products

To develop reusable incontinence products, blend nonwovens of hollow viscose rayon (HVR) and super absorbent fibers (SAFs) were prepared using a needle-punching process and their liquid handling properties, such as the fluid absorption capacity, fluid retention capacity, fluid absorption under load, moisture evaporation rate, and repeated water absorption were investigated. As the SAF content in the HVR/SAF blend nonwovens was increased, the fluid absorption capacity, fluid retention capacity, and fluid absorption under load increased, whereas the moisture evaporation rate decreased. SAF had a more significant effect on fluid retention than fluid absorption. In the case of HVR/SAF(8/2) and HVR/SAF(7/3), more than 100 % of the fluid absorption capacity was retained even after 5 cycles of repeated water absorption tests. Overall, the HVR/SAF blend nonwovens are good candidates for reusable incontinence products.     

Effects of coagulation bath temperature on polyurethane-based hollow fiber membrane morphology

Polyurethane-based hollow fiber membranes were prepared via melt-spinning method. Effects of coagulation bath temperature (CBT) on membrane outer surface and inner surface morphology were studied in detail by image analysis software. Based on the SEM images, membrane surface pore diameter and porosity were calculated, whereas the interconnected pore size and its distribution were determined using capillary flow porometer. Results show that increasing CBT could improve the membrane outer surface porosity at least twice. Thinner hollow fiber membrane with larger inward water flux could be prepared at higher CB-I (the first coagulation bath) temperature. Higher CB-II temperature (the second coagulation bath) could cause pore contraction and reduce the average diameter of outer surface pore. CBT in the early stage controlled the obtained membrane pore size and its distribution.     

Sound absorption and viscoelastic property of acoustical automotive nonwovens and their plasma treatment

Sound absorption property, viscoelastic property and the effect of plasma treatment of four automotive nonwoven fabrics on these properties are discussed in this research paper. Needle-punched fabrics used for vehicle headliner include 2 polyester fabrics made of hollow polyester fibers or solid polyester fibers, and 2 polypropylene-composite cellulose fabrics made of jute fibers or kenaf fibers, manufactured with the same web structure of apparent fabric density and fabric thickness. Hollow polyester fiber fabric has the highest sound absorption and the highest loss factor, the second highest is jute fiber fabric. The viscoelastic property is found to be related to the sound absorption property of fabric. The plasma treatment on nonwoven fabrics changes their sound absorption and viscoelastic property as well as their fabric weight and pore size. Hollow polyester fabric shows the increased sound absorption and viscoelastic property after the treatment with the increased pore sizes, while regular polyester fabric displays insignificant changes. The cellulose fabrics are more affected by plasma treatment compared to the polyester fabrics in terms of fabric weight loss and pore size, and jute fabric is more affected than kenaf fabric due to fiber weakness. The jute fabric demonstrates the decreased sound absorption and viscoelastic property, while kenaf fabric shows the increased sound absorption with the unchanged viscoelastic property after the treatment.     

Effects of spinning processes on HVI fiber characteristics and spun yarn properties

The effects of opening, carding, and repeated drawings on single fiber and bundle cotton characteristics were studied by employing Mantis®, AFIS® and HVI Testers. Some of the significant changes in single fiber properties were found to be due to process parameters as well as the changes in the fiber crimps, parallelness of fibers within HVI beards, and the actual changes in the tensile properties of the fibers. The study showed that the HVI test data taken just prior to spinning had the highest correlation with the yarn tensile properties. Based on the study results, we point out the potential of HVI for future quality and process control in spinning by recommending a set of expanded HVI output that is more scientific and comprehensive for the future control needs.     

Effects of recycling processes on physical, mechanical and degradation properties of PET yarns

Mechanical properties and the long-term degradation properties of the recycled PET yarns are typically lower than the virgin PET yarns due to the contaminants coming from non-PET bottles, labels and caps etc. For environmental reasons, recycling of post-consumer polyester bottles into textile fibers has become commercially attractive. We studied mechanical and chemical recycling processes and examined their effects on yarn properties such as tensile properties, thermal characteristics, hydrolysis and photo-degradation. It was found that the virgin and the chemical recycled yarns with sufficient purification show similar processability, physical and mechanical properties, and long-term degradation behavior. The results provide useful information on recycled PET yarns for processability and serviceability for the high-end use.     

Interaction of antibiotic with PAN and cationic-dyeable PET fibers in development of infection resistant biomedical materials

Interaction of a representative antibiotic, doxycycline (Doxy), with commercial poly(acrylonitrile) (PAN) and cationic-dyeable poly(ethylene terephthalate) (PET) fiber was studied in development of infection resistant biomedical materials. Regular PET was also employed for a comparison purpose. Their interactions were investigated at different treatment temperatures, times, and pHs. Fibers were also hydrolyzed by 1 % NaOH for 1 or 2 hours at 85°C and 100°C to study effect of hydrolysis on antibiotic sorption. Infection-resistant characteristics of the substrates were evaluated by zone of inhibition (ZOI) test. Results revealed that a significant chemical change occurred in PAN and cationic-dyeable PET due to hydrolysis. Additional functional groups obtained by hydrolysis not only enhanced sorption of the antibiotics but also provided greater ZOI values, indicating substantial improvement in sustained infection resistance properties.     

Fabrication and characterization of PET nanofiber hollow yarn

In this study, various concentrations of polyethylene terephthalate (PET) polymeric solution were investigated to produce hollow nanofiber yarn. First, the electrospining apparatus was designed in a way that to put PVA multifilament in the core and to twist PET nanofibers onto multifilament yarn as a sheath simultaneously, followed by dissolving PVA yarn in hot water, PET hollow nanofiber yarn was produced. In this survey, it has been observed that the average thickness of sheath increased by increasing concentrations of PET polymeric solution. Results showed that maximum efficiency of extracting the PVA multifilament from the hollow yarn under certain conditions (concentration of 18 % (w/v) of PET, applied voltage of 10 kV, and flow rate of 0.0526 ml/h) was more than 85 %. The mechanical and physical properties of PET hollow yarns were investigated and indicated that the hollow nanofiber yarns at concentration of 30 % and 18 % polymeric solution had the lowest strength and the highest regain moisture, respectively.     

Studies on hollownesss regulation and properties of crosslinked hollow phenolic fibers

The hollowness of crosslinked hollow phenolic fibers was regulated successfully from 9 % to 80 % by adjusting the curing temperature of the partially crosslinked fibers. The partially crosslinked fibers was studied in detail by mass gained, tensile strength, solvent dissolution, SEM, IR, and TG analysis, and the prepared hollow phenolic fibers with different degrees of hollowness were characterized with SEM, tensile strength, TG-DSC and TG-MS. The results show that the factor determining the hollowness is the crosslinked extent of the partially crosslinked fibers and the hollow fibers with different degrees of hollowness have similar crosslinkage, mechanical properties and thermal stability.     

A study on heat insulation of composites made of recycled far-infrared fibers and three-dimensional crimped hollow polyester fibers

Far-infrared polyethylene terephthalate (FPET) fibers have been commonly used in clothing in order to attain heat retention, and the combination of three-dimensional crimped hollow polyethylene terephthalate (TPET) fibers makes the clothing to be fluffy and air permeable, and thereby improves the wearing comfort. This study aims to make thermally insulating nonwoven composites by using recycled far infrared fibers. The composites are used to cover the heat transfer lines and prevent the heat emissivity. A specified amount of low-melting-point polyethylene terephthalate (LPET) fibers and FPET and TPET fibers at different ratios are blended, followed by being needle punched at 100-300 needles/min, and then hot pressed at 120 °C, in order to form thirty nonwoven composite types. These nonwoven composites are measured for their porosity, thickness, and air permeability, and are tested for thermal insulation and temperature-rise slope under a constant ambient temperature.     

Relationship between fiber orientation distribution function and mechanical anisotropy of thermally point-bonded nonwovens

Current efforts to establish links between geometrical features and mechanical performance of nonwoven fabrics in general, and of point-bonded (spot-bonded) nonwovens in particular has been made using the measurements of Fiber Orientation Distribution Function (ODF) and tensile modulus which occurs during controlled-deformation experiments. Image analysis technique (using the Fast Fourier Transform) was used to quantify the fiber orientation distribution. The results suggest that, within a typical window of processing conditions, the fiber orientation has a significant influence on the anisotropical behavior of nonwoven. The data also suggest that mechanical anisotropy of thermally point-bonded nonwovens is likely to be governed by different load transfer mechanism according to the applied macroscopic tensile direction.     

The design and manufacture of profiled multi-channeled hollow polyester fibers

A Numerically Controlled Electrical Discharge Machining (EDM) System was developed for the production of spinnerets that can be used to manufacture profiled multi-channeled hollow fibers with noncircular cross-section full of 16/17 holes of circular shapes. Four spinnerets of different slit shape were made, and four hollow fibers were produced accordingly. The first trial with I-type slit failed due to the adhesion between melt polymer jets when they were extruded from the spinneret and also the melts didn’t spread well. In the second trial, fibers were obtained from a spinneret with both “C” and “I” slits. Again it failed to produce results expected, as the 4 holes in the center of a fiber appeared to be larger than the other 12 holes. The third trial that produced fibers from a spinneret with “C” slit was a success. They were fibers with 15 holes of almost the same size. This technique was then adopted for mass production. This time silver electrode was used as copper electrode couldn’t achieve the goal. In the mass production, profiled hollow fibers were obtained with 17 holes of similar dimensions, uniformly distributed in the cross-section. Porosity of the fibers reached 20.2 %. It is now clear that this technique is useful for manufacturing highly porous profiled fibers with specially designed features.     

Structural factors and physical properties of needle-punched nonwovens based on Co-PET/PA bicomponent fibers via alkali treatment

Needle-punched nonwovens are widely used in industrial fields. However, they are limited to some applications such as high-efficiency filters, high-performance synthetic leathers, and high-absorption wipes because of their low surface area and large pore size. In this study, needle-punched nonwovens composed of Copolyethylene terephthalate (Co-PET)/Polyamide (PA) sea-island bicomponent fibers were treated in NaOH solution with various conditions for preparing nonwovens composed of ultra-fine fibers. The effect of NaOH concentration and treatment temperature on the structural factors and physical properties of nonwovens was investigated. The morphological structures of Co-PET and PA components were analyzed by scanning electron microscope. After alkali treatment, fiber diameter was significantly reduced from 23.65 to 3.95 μm, specific surface area of nonwovens increased more than five times, calculated and experimental mean pore diameter decreased by 83.6 % and 20.8 %, respectively. By increasing NaOH concentration and treatment temperature, pore diameter was reduced, thereby decreasing the air permeability of nonwovens. Meanwhile, tensile strength increased and tearing strength decreased as NaOH concentration and treatment temperature were increased in both machine and cross direction, respectively. The treatment temperature of alkali treatment was significantly influenced by the physical properties of nonwovens.     

Moisture and thermal permeability of the hollow textured PET imbedded woven fabrics for high emotional garments

This study examined the effects of the total porosity, pore size, and cover factor on the moisture and thermal permeability of woven fabrics made from DTY (draw textured yarns) and ATY (air jet textured yarns) composite yarns with hollow PET (polyethylene terephthalate) yarns. The wicking of the hollow composite yarn fabrics was found to be superior to that of the high twisted yarn fabrics, which may be due to the high porosity in the hollow composites yarns, but this was not related to the cover factor. The drying characteristics of the hollow composite yarn fabric with high porosity were inferior compared to the high twisted yarn fabrics due to the large amounts of liquid water in the large pores, which resulted in a longer drying time of the fabric. The thermal conductivity of the hollow composite yarn fabrics decreased with increasing measured pore diameter due to the bulky yarn structure. The effects of the hollowness of the yarn on the thermal conductivity were more dominant than those of the yarn structural parameters. The air permeability increased with increasing measured pore diameter but the effects of the cover factor on the air permeability were not observed in the hollow composite yarn fabrics. The effects of porosity on the moisture and thermal permeability of the woven fabrics made from the hollow composite filaments were found to be critical, i.e., wicking and air permeability increase with increasing porosity. In addition, the drying rate increased with increasing porosity and the thermal conductivity decreased with increasing pore diameter, but were independent of the cover factor.     

Study on damping and mechanical properties of nano-titanium dioxide/acrylonitrile butadiene-rubber hollow fiber

TiO₂/NBR-PVC hollow fibers were spinned by NBR casting solution blended PVC with nano-titanium dioxide (TiO₂). The effect of NBR-PVC hollow fiber damping and mechanical properties aroused by loading TiO₂ were studied. Results showed that the hollow fibers loaded TiO₂ increased in tensile strength, storage modulus, stiffness and glass transition temperature, while decreased in tanδpeak and breaking tensile elongation. The damping of the TiO₂/NRR-PVC hollow fiber were not only linked to the dosage of TiO₂, but also related to the degree of dispersion in matrix.     

Comparison of the structure-property relationships for PTT and PET fibers spun at various take-up speeds

A comparison of poly(trimethylene terephthalate)(PTT) and poly(ethlene terephthalate)(PET) fibers spun at various take-up speeds was presented. Fiber characterization included tensile and thermal properties, optical birefringence, density, sonic modulus, boil-off shrinkage, and wide-angle X-ray diffraction. The phenomenon of stress-induced crystallization was inferred from the X-ray diffraction diagrams for fibers spun with take-up speeds over 4000 m/min. The tenacity and elongation of PTT and PET fiber showed typical results, but the initial modulus of PTT fiber was nearly unchanged over the entire take-up speed range (2000–7000 m/min), whereas that of PET, as expected, increased monotonically with increasing take-up speed. This divergent behavior could be explained by the different molecular deformations in the c-axis as determined from X-ray diffraction patterns. The fiber crystallinity, density, and heat of fusion of both polymers increased with take-up speed. The boil-off shrinkage decreased with increasing take-up speed. The optical birefringence of the two fiber types showed a maximum level at a take-up speed of ca. 5000 m/min. The melting temperature behavior of PTT fiber was different from that of PET fibers. It was found that PTT is less sensitive to stress induced changes at high spinning speeds than is PET.     

我国植物纤维复合材料的发展现状及展望

综述了近年来我国植物纤维复合材料的发展现状及特点,并根据基体材料和增强体材料进行初步分类。简要概括了植物纤维复合材料的应用领域,总结了我国植物纤维复合材料的发展趋势。     

Effect of hybrid post treatments on the structural property and water flux of polysulfone hollow fiber membrane

The application of post treatments in preparation of high flux membranes is expanding rapidly. In this work, several hybrid post treatments have been introduced and used for change in the water flux of polysulfone (PSf) hollow fiber membranes. Dry wet spinning method was employed for fabrication of PSf hollow fiber membrane from spinning dope in mass ratio of 15:5:80 of PSf/PVP-K90/NMP. The simultaneous effects of single and hybrid post treatments containing traditional hypochlorite; high pressure injection technique (HPI) of hypochlorite, hot air and hot water treatments on the morphology and water flux of fabricated hollow fibers has been investigated. AFM analysis and image processing of SEM microphotographs of hollow fibers were used for structural studies. The mechanical properties of hollow fibers as well as strain at break and strength also were studied. It was found that the pores size and surface roughness parameter of hollow fiber membranes have been increased after traditional hypochlorite, HPI technique and hot water treatments while decreased when heat treated in air. In general all the employed hybrid post treatments caused to increase in the pores size of hollow fibers although the pores size increase rate in the membranes treated by the hybrid post treatments involving hot air was much lower than the others. The mechanical properties of hollow fibers have been decreased after hybrid and single post treatments containing traditional hypochlorite, HPI technique and hot water treatment while slightly increased after post treatments containing hot air. It was stated that the fabricated PSf hollow fibers were considerably affected by the employed hybrid post treatments. This can be attributed to the combine effects of used post treatments.     

Basic study on the two-tone color dyeing of PET and PVC wig fibers by carrier dyeing method

PET or PVC wig fibers are usually colored by the dope dyeing method in which the pigment or color master batch is mixed before the spinning process. However, the colored fibers need to be dyed again to obtain a two-tone color along the longitudinal fiber direction. In this study, PET and PVC fibers were dyed by the carrier dyeing method using a disperse dye, and the dyeing behavior was investigated. The fiber was dyed at various carrier and dye concentrations. The dye uptake increased with increasing carrier concentration or dye concentration. The saturation of the dye uptake was observed in each case. No change of the glass transition temperature (T_g) was observed in the 1st run of the DSC thermogram, however, a decrease in the value of T_g was observed in the 2nd run performed after the 1st run sample was quenched and re-measured. The reduction in the value of T_g implies that the carrier acted as a plasticizer in the fiber and enhanced the segmental mobility of the polymer chains. The dyeing temperature and carrier concentration were varied and the diffusion coefficients of the dye and activation energy were measured. The activation energy was increased at a higher carrier concentration, because the carrier acted as a plasticizer and lowered the energy barrier to the penetration of the dye molecule into the polymer chains.     

Effect of fibers on the flow property of turbulent fiber suspensions in a contraction

In the flow of turbulent fiber suspensions flowing through a contraction with rectangular cross-section, the Reynolds averaged Navier-Stokes equation with the term of additional stress resulting from fibers was solved with the Reynolds stress model to get distributions of the mean velocity, mean pressure, turbulent kinetic energy and turbulent dissipation. It is found that the mean velocities at exit are small around the center and large near the wall for higher concentration. Fibers reduce turbulent intensity and turbulent dissipation at central line, but enhance them over the cross section at exit. Fibers have no effect of restraint on the turbulence in the contraction flow. The additional stress resulting from fibers plays a role in the increase of drag.     

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.