Ratio Of Polyvinyl Alcohol Research Articles

Preparation and characterization of sodium alginate/polyvinyl alcohol hydrogel containing drug-loaded chitosan nanoparticles as a drug delivery system

In this study, an optimal combination of sodium alginate (SA)/polyvinyl alcohol (PVA) hydrogel containing Rosuvastatin-loaded chitosan (CS) nanoparticles was fabricated as the drug delivery system (DDS). First, the drug-loaded nanoparticles were synthesized by the ionic gelation method. Then, several hydrogel films with different ratios of SA:PVA were prepared. Subsequently, different concentrations of drug-loaded CS nanoparticles were added to a hydrogel with an optimal SA:PVA ratio. The results of the tensile test showed that in the SA:PVA ratio of 7:3 and 3 wt % of drug-loaded CS nanoparticles, the hydrogel film was achieved with optimal mechanical properties. The mean size of drug-loaded CS nanoparticles determined by the AFM and DLS methods was in the range of approximately 100–150 nm. The release profile of the Rosuvastatin drug from the fabricated DDS illustrated that all the loaded drug was released within 24 h, and the CS nanoparticles had a significant effect on the release behavior. Also, the cytotoxicity of the fabricated DDS on the human fibroblast cells demonstrated a high cell viability after 72 h of incubation. Therefore, the fabricated SA/PVA hydrogel containing drug-loaded CS nanoparticles depicted a great potential as the delivery system for the controlled release of the Rosuvastatin drug.

Effect of elevated temperature on axially and eccentrically loaded columns containing Polyvinyl Alcohol (PVA) fibers

Polyvinyl Alcohol (PVA) fiber was developed more than 80 years ago in Japan. They are heavily used in non-structural applications and in Engineered Cementitious Composites (ECC) mainly for beams and thin slabs sections. There are gaps in the research regarding their performance in other structural elements and at elevated temperatures. The aim of this work is to study the behavior of reinforced concrete columns containing PVA fibers after being subjected to elevated temperatures and then loaded either concentrically or eccentrically. A total of thirty-six reinforced concrete columns, having constant longitudinal reinforcement, were experimentally tested under different load eccentricity ratios (0.0, 0.50, and 1.0). Different ratios of PVA, 0.75%, 1.50%, 2.25% were included in the concrete mixes. The studied columns were exposed to elevated temperature before loading. It was observed that columns containing PVA fibers had higher ultimate loads, higher ultimate deflection, less crack widths, higher ultimate deflection, higher energy absorption, and higher temperature resistance compared to normal reinforced concrete columns. In addition, these columns didn’t show any sign of spalling due to the fiber bridging effect of PVA fibers unlike other studied normal reinforced concrete columns without fibers. It was found that addition of 1.50% fiber content showed better performance for centrically loaded columns while this was raised to be 2.25% for eccentrically loaded columns. The ultimate load of the columns exposed to elevated temperature rapidly decreased with increasing the duration of temperature to different magnitudes depending on the percentage inclusion of PVA fibers. It was found that ductility and energy absorption for columns including 1.5% PVA were higher than their companions without fibers after temperature exposure. It was observed that the energy absorption of eccentric columns exposed to temperature for up to two hours was still higher than that of their companions without fibers by 40% for eccentricity ratio of 1.0.

One-Pot Synthesis of Doped-Polypyrrole/Fe₃O₄ Nanosphere Composites and Their Microwave Absorption Performance.

Doped-polypyrrole/Fe₃O₄ (D-PPy/Fe₃O₄) nanospheres were successfully synthesized via a onepot process. In this process, polyvinyl alcohol (PVA) plays an important role in the construction of polypyrrole nanoparticles, and Fe3+ ions were the oxidant and the only raw resource of Fe₃O₄. The morphology, magnetic properties, and electromagnetic microwave absorption properties of D-PPy/Fe₃O₄ composites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), a vibrating sample magnetometer (VSM) and a vector network analyser (VNA). The results indicate that D-PPy/Fe₃O₄ nanospheres become more disperse and regular due to the addition of PVA. The influence of the mass ratio of PVA to pyrrole on the microwave absorption performance of the D-PPy/Fe₃O₄ composites was also investigated. When the mass ratio of PVA/pyrrole was 0.75:1, the minimum reflection loss (RLmin) value of the D-PPy/Fe₃O₄ composites reached -41.3 dB at 7.7 GHz with a thickness of 3.0 mm. The microwave interference cancellation of interface reflection, nature resonance loss and current loss are the main reasons for the loss of electromagnetic microwaves for the as-prepared D-PPy/Fe₃O₄ composites.

PVA-GELATIN HYDROGELS CONTAINING ROSEMARY ESSENTIAL OIL FOR WOUND DRESSINGS

Wound healing represents one of the most important processes evaluated in the biomedical field. In this regard, healing is defined as a dynamic and complex process in which the tissue integrity and the normal functions of the damaged tissue are restored. The purpose of this research was to achieve the main characteristics of an ideal wound dressing to prevent maceration, provide a moist environment, remove the exudate that is accumulated from the wound and to maintain a proper permeability to the wound bed. Different hydrogels were designed and developed through the esterification reaction of polyvinyl alcohol (PVA) with gelatin (GELL). The hydrogels were prepared in various weight ratios of PVA:GELL (4:1 and 1:4), by adding rosemary essential oil as an active compound. The incorporation of Rosemarinus officinalis L (rosemary) essential oil in PVA/GELL hydrogels represents a potential method for the improvement of the wound healing process. Further, the developed hydrogels were applied by immersion on cotton gauze. The synthetized specimens were evaluated from morphological and rheological point of view, by performing Optical Microscopy, fluid uptake ability and porosity measurements.

Electrospun Ultrafine Fibers from Black Bean Protein Concentrates and Polyvinyl Alcohol

In this study, ultrafine fibers were produced from black bean protein concentrates (BPCs) and polyvinyl alcohol (PVA) by electrospinning. The BPC was denatured under acidic (pH 2) or basic (pH 11) conditions. Polymer solutions containing different PVA concentrations (11% or 21%, w/v) and different BPC: PVA ratios (50:50 or 75:25, v/v) were used for fiber production. The electrical conductivity and rheological properties of the fiber-forming solutions were evaluated, as well as the morphology, size distribution, infrared spectrum, and thermal properties of the electrospun fibers. The fibers showed a homogeneous morphology and diameters ranging from 115 to 541 nm. Fibers from the solution containing BPC denatured at pH 11, 11% PVA, and 75:25 (v/v) BPC: PVA presented the lowest diameter, and those from BPC denatured at pH 2 had less beads than the fibers obtained from BPC denatured at pH 11. The solution formulation affected the thermal properties of the fibers, with weight loss increases ranging from 39.0% to 60.9%. The polymeric solutions containing PVA and BPC (whether denatured under basic or acidic conditions) resulted in ultrafine electrospun fibers with highly favorable characteristics that could potentially be used for the encapsulation of bioactive compounds and food applications.

Fabrication and characterization of thymol-loaded nanofiber mats as a novel antimould surface material for coating cheese surface

Abstract This study covers fabrication and characterization of thymol-loaded nanofiber (TLNs) mats and evaluation of their potential to be used as novel antimould surface coating material for limitation of mould development of Aspergillus parasiticus on kashar cheese surface. Different ratios of polyvinyl alcohol (PVA)/whey protein (WP) were electrospun to yield cylindrical and fine (⁓370 nm in diameter) polymeric nanofiber mats. The fabricated nanofibers were characterized in terms of their zeta potential, electrical conductivity, molecular, thermal and morphological properties. These results revealed that there were intermolecular interactions between thymol and functional groups of PVA and WP. The most uniform nanofiber structure with smooth beadless appearance could be observed in thymol-free nanofibers (TFNs) fabricated from 60/40 ratio of PVA/WP. The nanofiber diameter and electrical conductivity values were significantly increased by increase in PVA and WP ratios, respectively. The nanofiber mats had dispersion (−7.60 mV of ζ potential) and good thermal stability (an endothermic peak at ⁓215 °C) properties. In vitro antimould activity tests results showed that TLNs mats could show a higher efficiency against mycelial growth of A. parasiticus than free thymol. In situ test results obtained at the 7th storage day confirmed in vitro test results with respect to visual inspections on coated and uncoated cheese surface, revealing that the coating of kashar cubes with TLNs prevented the growth of A. parasiticus on the coated cheeses. The results of this study shows that TLNs mats can be used an antimould surface material to limit mould growth on coated cheeses during storage period.

Biopolymeric pellets of polyvinyl alcohol and alginate for the encapsulation of Ib-M6 peptide and its antimicrobial activity against E. coli

The encapsulation of Ib-M6 antibacterial peptide in pellets of polyvinyl alcohol (PVA) and polyvinyl alcohol-alginate (PVA-Alg) matrices was carried out in order to explore its controlled release and activity against Escherichia coli K-12. The pellets were obtained by combined ice segregation induced self-assembly (ISISA) and freezing-thawing methods and their microstructure was studied by scanning electron microscopy. Bromothymol blue was used as a model compound to study the transport mechanisms and release from pellets. The results show that there is a significant effect of the total concentration of PVA precursor solutions, the mass ratio of PVA of different molecular weights and the addition of alginate on the microstructure and transport properties of pellets. The antibacterial activity of Ib-M6 against Escherichia coli K-12 was not affected by the encapsulation in PVA pellets. However, the release of Ib-M6 from PVA-Alg pellets was not possible, probably due to the electrostatic interaction of positively charged Ib-M6 and negatively alginate structure. Nonetheless, the controlled release of Ib-M6 from polymeric matrices can be fitting by modifying parameters such as the concentration and type of polymer precursors.

Facile fabrication of PVA nanofiber coated with PEDOT as a counter electrode for dye-sensitized solar cell

Polyvinyl alcohol (PVA) nanofibers coated with poly(3,4-ethylenedioxythiophene) (PEDOT) as a counter electrode (CE) is a promising material to substitute platinum CE for dye-sensitized solar cell due to the high conductivity of PEDOT and high surface area to volume ratio of PVA. PVA nanofibers and PEDOT were prepared through facile techniques of electrospinning and electropolymerization, respectively. Field emission scanning electron microscopy revealed that PEDOT was distributed evenly on PVA nanofibers with porous cauliflower-like structure. PVA/PEDOT nanofibers CE had low charge transfer resistance (Rct) and possessed a good electrocatalytic activity with a low value of peak-to-peak separation (Epp = 0.34 V), thus an improved efficiency of 2.11% was obtained in comparison to platinum (1.14%), PEDOT (1.39%) and PVA nanofibers (0.017%).

A fast-response and highly linear humidity sensor based on quartz crystal microbalance

A fast-response and highly linear humidity sensor based on quartz crystal microbalance (QCM) was prepared by using polyvinyl alcohol (PVA) and nano-silica composites as sensing film. The mass ratio of PVA to nano-silica and the total mass of sensing film which can significantly influence the response time and linearity of humidity sensor were well discussed. The results show that the optimal mass ratio of PVA to nano-silica is 1:1.5 and the total mass of the sensing film coated on the surface of QCM is 1.0 μg. Under the optimum conditions, the frequency shifts linearly respond to the relative humidity. The prepared humidity sensor has short response time (5 s), short recovery time (21 s), good stability and reproducibility. The developed humidity sensor is expected to be used for the detection of humidity in practice.

The effect of blend ratios on physico-mechanical properties and miscibility of cross-linked poly(vinyl alcohol)/urea blends

The present study investigates the effect of blend ratios on the miscibility and physico-mechanical properties of polyvinyl alcohol (PVA)/urea (U) blends. PVA/U blends were synthesized in aqueous solution with different blend ratios 65/35, 50/50 and 35/65 respectively, using glacial acetic acid as crosslinking. The properties of PVA/U blends examined included FT-IR, 1H NMR, 13C NMR, TGA, DSC and scanning electron microscopy (SEM). The obtained results showed that the miscibility and physico-mechanical properties of PVA/U blends are strongly dependent on PVA ratio in the blends. FT-IR spectroscopy was used to check the hydrogen bonding interaction between PVA and U in the blends. The formation of hydrogen bond was through the lone pair attraction from nitrogen atoms of U towards protonated hydroxyl of PVA. These blends have a single glass transition indicating that these blends are able to form a miscible phase due to the formation of hydrogen bonds. The addition of glacial acetic acid as cross-linking improved the thermal analysis of the blend. The scanning electron microscopy of PVA/U showed crystals of varying sizes with flake shapes compared to the pure PVA.

Preparation and characterization of antimicrobial films based on nanocrystalline cellulose

ABSTRACTNanocrystalline cellulose (NCC) has great potential in applications in medical and food packaging due to its abundance, high specific surface area, biodegradability, biocompatibility, and reproducibility. N‐Halamine is one of the most effective antibacterial agents, with broad‐spectrum efficacy against microorganisms, good stability, and reproducibility. Due to the nanosize effect and high specific surface area of NCC, N‐halamine‐modified NCC is potentially an excellent biocidal compound. In this paper, an N‐halamine precursor 1‐hydroxymethyl‐5,5‐dimethylhydantoin (HDH) was used to modify NCC with cyanuric chloride (cych) as the bonding agent. After chlorination, the produced NCC‐cych‐HDH‐Cl became antibacterial. The synthesized NCC‐cych‐HDH‐Cl was added to a chitosan (CS) and polyvinyl alcohol (PVA) solution to prepare antibacterial films. The optimum mixing ratio of PVA and CS in the PVA/CS films and concentration of NCC‐cych‐HDH‐Cl were investigated. The surface morphologies and mechanical properties of the antibacterial films were characterized with scanning electron microscopy, transmission electron microscopy, and mechanical strength tests. The results indicated that the film with 90/10 PVA/CS and 7.0% loading of NCC‐cych‐HDH‐Cl exhibited excellent tensile strength. The antibacterial film with 5.91 × 1017 atoms/cm2 of active chlorine displayed an excellent antibacterial property against Staphylococcus aureus (ATCC 6538) and Escherichia coli O157:H7 (ATCC 43895). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47101.

Sericin Ameliorates the Properties of Poly(Vinyl Alcohol) Hydrogel Prepared by Simple Repeated Freeze-Thaw Process without the Use of Chemical Crosslinking

Hydrogel of polyvinyl alcohol (PVA) and sericin can be easily produced using a repeated freeze-thaw process. The effects of polymer concentration (4-8 %wt), blending ratio of PVA/sericin (100/0-50/50), and the number of freeze-thawing cycle (4, 8, and 12 cycles) on chemical and physical properties of the hydrogels obtained were studied. We here showed that higher polymer concentration, higher PVA ratio, and more cycles of freeze-thawing produced the hydrogels with high gel (crosslinked) fraction (>90), wall-like structure, and high compressive modulus (100-170 kPa). When the sericin ratio was increased, the hydrogels showed less gel fraction (60-80), more porous structure with highly interconnected pores, and better swelling ability (up to 8-9 times of its original state). The formation of the PVA/sericin hydrogels was occurred by the conformational changes of both PVA and sericin. The secondary structures of PVA and sericin turned to more stable crystalline conformation during the freeze-thawing process, as confirmed by fourier transform infrared (FTIR) spectroscopic results. Furthermore, all hydrogels were not toxic to human skin keratinocytes (HaCaT) cells while the anti-oxidant activity of sericin component in hydrogels was confirmed. We concluded that the freeze-thawing process was a simple and effective technique for fabrication of PVA and sericin, which both are water-soluble, into the stable hydrogels without the use of any chemical solvents or further crosslinking. More importantly, sericin enhances the biological activities of the hydrogels, allowing the use of this hydrogel in various medical applications such as wound dressing.

The conducting polymer electrolyte based on polypyrrole-polyvinyl alcohol and its application in low-cost quasi-solid-state dye-sensitized solar cells

The effect of polypyrrole (PPy) on the polyvinyl alcohol (PVA)-potassium iodide (KI)-iodine (I2) polymer electrolytes has been investigated and optimized to use in a dye-sensitized solar cell (DSSC). The different weight ratios of PVA: PPy (93: 2, 91: 4, 89: 6, 87: 8, and 85: 10 wt%) polymer electrolytes (PE) were prepared by solution casting. Structural, complex formation and surface roughness of the prepared electrolytes was confirmed by X-ray diffraction, FTIR, and atomic force microscopy (AFM) respectively. Conductivity plots of all polymer films showed increasing trend with temperature and concentration of PPy. The activation energy of the optimized system found to be 0.871 kJ mol−1. UV-visible spectrum was adopted to characterize the absorption spectra of the material revealed that increase in the absorbance with increasing PPy content and shifting the absorbance maximum towards lower energy. The indirect band gap decreased from 3.78 to 2.14 eV and direct band gap decreased from 3.88 to 2.71 eV. The EIS analyses revealed the lower charge transfer resistance of 3.029 Ω cm2 at the interface between CE and PE. The excellent performance was observed in the fabricated DSSCs using PVA (85%)/PPy (10%)/KI (5%)/I2 polymer electrolyte with a short-circuit current density of 11.071 mA cm−2, open-circuit voltage of 0.644 V, fill factor of 0.575, and photovoltaic conversion efficiency of 4.09% under the light intensity of 100 mW cm−2. Hence, the PPy content in polymer electrolyte influences the remarkable performance of low-cost DSSC.

Facile tool for green synthesis of graphene sheets and their smart free-standing UV protective film

Green, cost-effective and scalable method was developed for synthesis of graphene sheets from sugar beet leaves. Considerable graphene sheets were synthesized through drying, and carbonization of sugar beet leaves then, exfoliation from the obtained graphite flakes using ultrasonication in presence of polyvinyl alcohol (PVA). High quality less defected and large dimensions graphene sheets of 50% yield were obtained. The mass ratios of PVA and their effect on exfoliation were studied. Free-standing transparent graphene sheets thin film was developed of an average thickness of 136 µm. The transparent free-standing graphene sheets thin film transparent to visible rays and blocked harmful UV rays by ∼70% which is among the highest reported value for UV protective thin film. To the best of our knowledge this the first time of free-standing transparent graphene sheets film prepared from renewable source and used as UV filter. This work will open new avenues for using renewable and cost-effective UV protective materials and filters.

Influence of heating on spectroscopic, mechanical, and thermal properties of reduced graphene oxide-poly(vinyl alcohol) composite films

The spectroscopic, uniaxial tensile, and thermal properties of reduced graphene oxide (rGO)-poly(vinyl) alcohol (PVA) composite films produced by using rGO synthesized using modified Hummer's method with varying weight ratio of rGO up to 10% were investigated by using an uniaxial tensile tester, Fourier Transform Infrared (Ft-IR)/Attenuated Total Reflectance (ATR) spectroscopy, and Differential Scanning Calorimeter (DSC) methods after heating process at different temperatures from room temperature to 200 °C. For unheated composite films, with increasing rGO weight ratio up to 10%, the Young's modulus of rGO-PVA films increased by approximately 2–3 times, conversely the strain at break values decreased greatly by about 40–50%. The heating process led to the significant improvement in the tensile strength and the Young's modulus, and great decrease in extensibility with respect to the unheated samples, e.g., the tensile strength and Young's modulus increased by 3–4 times and 8–10 times, respectively, for the heating temperatures up to 150 °C. With increasing heating temperature, the stress-strain curve of rGO-PVA composite films turned from that of ductile and amorphous polymer to that of more brittle and rigid polymers. With increasing rGO content, the glass transition, the crystallization, and the melting temperatures increased and heating process generally shifted these temperatures to higher values. The great contribution of rGO content and the heating to the improvement of especially mechanical properties of rGO-PVA composite films thanks to the strong intermolecular interactions of rGO nanosheets with the PVA matrix molecules through hydrogen bonding and to the changes in the crystallinity ratio of PVA was shown in detail in the analysis of the spectral results. The relationship between the changes in the mechanical, structural, and thermal properties of the studied composite films was determined by using tensile testing, Ft-IR/ATR, and DSC methods.

Conductivity and structural studies of PVA based mixed-ion composite polymer electrolytes

The solid membranes having different ratios of poly-vinyl alcohol (PVA), sodium perchlorate (NaClO4) and lithium perchlorate (LiClO4) were prepared using solution casting technique. The mixed-ion composite polymer electrolytes were characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and conductivity measurement investigations. The XRD study confirms the amorphous nature of the mixed-ion composite polymer electrolytes. FTIR analysis has been used to characterize the structure of polymer which confirms the polymer and salt complex formation. The temperature dependent nature of ionic conductivity of the mixed-ion composite polymer electrolytes was determined by using conductivity meter (EC-035WP ERMA Inc, made in Japan). The ionic conductivity of the electrolyte was found in the range of 10-3 - 10-4 S/cm at room temperature.

Identification of potential hydrophobic properties of carbon layer from the coffee bean waste

The significant increase of waste due to vast development of human civilization and industrialization has plunged humanity into various environmental issues. Nowadays, the concern on waste handling and conversion into more valuable material has become one of hot research topics. Biomass waste has great abundance with various types that can be utilized for many applications such as landfill, recycled-material, adsorbent, separation, catalysis, and so on. In this study, coffee bean waste (CBW) was used as a source to produce hydrophobic layer. The CBW was converted into amorphous carbon using simple carbonization method at 500 °C, dispersed in acetic acid and then mixed with polyvinyl alcohol (PVA) at low temperature heating. In order to investigate effects of composition on hydrophobicity properties, ratio of carbon and PVA was varied. In addition, acetic acid was used to evaluate effect of dispersant on hydrophobic properties. SEM analysis reveals unique morphology of carbon layer. The measurement of contact angle demonstrates that this unique morphology possesses comparable hydrophobicity with that of some well-known materials. Fourier transform infrared spectroscopy (FTIR) analysis confirms the effect of PVA bonding and carbon layer on its hydrophobicity.

Highly Structured Polyvinyl Alcohol Porous Carriers: Tuning Inherent Stability and Release Kinetics in Water.

Polyvinyl alcohol (PVA) porous carriers were prepared by means of ice templating of aqueous solutions containing of 90 kD and/or 16 kD PVA. The carriers were loaded with traces of a colored probe (methyl orange) to screen their release properties, once immersed in water. The carriers prepared from solutions containing 90 kD and 16 kD PVA resulted in intimate polymer mixtures, exhibiting physical properties that stand in between those of the bare 90 kD or 16 kD PVA end members. The freezing protocols employed were adapted to prepare carriers textured in the form of either monolithic scaffolds (directional constant freezing rate) or millimetric pellets (flash-freeze). Monolithic carriers remain stable in aqueous solution, and the probe release is governed by a swelling–diffusion mechanism. The kinetics of probe release can be tuned from minutes to hours by either increasing the total PVA content or the 90 kD-to-16 kD PVA ratio in the parent solution. In contrast, pellets (millimetric carriers) immersed in water release the probe on the scale of minutes, irrespective of the PVA content or composition. However, the PVA content and the 90 kD-to-16 kD PVA ratio dramatically affect the stability of the carriers. Depending on the formulation, these small carriers can develop swelling, erosion, or eventually massive dissolution.

Preparation of phase change material emulsions with good stability and little supercooling by using a mixed polymeric emulsifier for thermal energy storage

A mixed polymeric emulsifier consisting of polyvinyl alcohol (PVA) and polyethylene glycol-600 (PEG-600) was explored for preparing high-performance phase change material emulsions (PCMEs) containing the paraffin with a melting point of 62–64°C. After the effects of the mass ratio of PVA to PEG-600, the mass ratio of the mixed emulsifier to the paraffin and the homogenization rate on the size distribution, viscosity and dispersion stability of the PCMEs containing 20wt% paraffin were systematically investigated, the optimal emulsifying process parameters have been determined to be the mass ratio of PVA to PEG-600 of 50:50, the mass ratio of the mixed emulsifier to paraffin of 1:5 and the homogenization rate of 10,000rpm. Accordingly, the PCMEs with the paraffin mass fractions varying from 10wt% to 30wt% were prepared. It is found that the paraffin has been well dispersed in water in the form of sphere-like droplets with average diameters ranging from 3µm to 11µm in the obtained PCMEs. Significantly, the PCMEs with different mass fractions of the paraffin exhibit no supercooling, owing to the function of the mixed polymeric emulsifier as a nucleating agent. The apparent specific heat of PCMEs are 1.51–2.18 times as high as that of water at the phase transition temperature region, due to the existent of the paraffin in them. Their apparent thermal conductivity gradually decreases with an increase in the mass fraction of the paraffin, while the viscosity increases significantly with mass fraction of the paraffin at the same temperatures. Furthermore, the pumping power consumption of the PCMEs shows a drastic reduction as compared to that of water at the same heat storage capacity. It is revealed that the PCMEs show great potential for use as a novel heat transfer fluid (HTF) in thermal energy storage (TES) systems.

The effect of core-sheath proportion on the characteristics of fabrics produced with hollow yarns: part II comfort and mechanical properties

The study aims to investigate the effect of hollow yarn structure and the sheath-core proportion of hollow yarns on the permeability properties of the knitted fabrics. In order to accomplish this, core yarns in the yarn count of 59 tex were produced by using cotton, viscose, wool, and polyester fibers in the sheath and different ratios of polyvinyl alcohol (PVA) in the core. After completion of yarn production on ring spinning frame, the yarns in the form of packages were used to produce plain knitted fabrics. Fabrics were then divided into two groups, one of which was washed during a time period in order to remove PVA from the core to obtain hollow yarn structure. Air and water permeability, and wicking properties of the knitted fabrics were measured before and after washing processes. Mechanical properties such as pilling and bursting strength of the fabrics were also examined. The results show that washing process and PVA proportion used to produce core spun yarns have a significant effect on the permeability and mechanical properties of the fabrics.