Antibacterial chitosan-reinforced poly(vinyl alcohol) fibers produced via wet-spinning: Structural, thermal, mechanical, and antimicrobial properties relevant for biomedical use

Summary: In this paper we have tried to find the relationship of thermal and mechanical properties i. e. thermal conductivity, tensile strength and Young's Modulus of the composite material. Two systems were selected; poly(vinyl alcohol)/sodium sulphate composite, and poly(vinyl alcohol)/lithium sulphate composite. Various concentrations of these salts were used to make composites of poly(vinyl alcohol). Films were grown, dried at room temperature and were subjected to mechanical, structural and thermal characterization. Thermal conductivity was determined at room temperature using polyethylene, silicon and quartz as reference. It was found out that the thermal conductivity of both the systems is highly dependent on the nature and the concentration of added salt in the polymeric composite. Thermal conductivity of the poly vinyl alcohol/ sodium sulphate composite, and poly vinyl alcohol/lithium sulphate composite, decreased with concentration of the salts in the polymer composite. These composites were also analyzed by XRD. Observed roperties were explained on the bases of their structure. Machenical properties such as tensile strength and Young's Modulus were also found out to be a function of the compostion of the composite

Chitosan:poly (vinyl) alcohol composite alkaline membrane incorporating organic ionomers and layered silicate materials into a PEM electrochemical reactor

The present study reports on an environment‐friendly and economically viable method of synthesizing graphene oxide (GO) using agricultural waste, specifically oak ( Quercus ilex ) fruit. The agricultural waste‐derived GO (AGO) is further used as a reinforcing filler in the fabrication of poly(vinyl alcohol) (PVA) polymer nanocomposites by employing a solution‐mixing process. A series of characterization methods have been used to assess the interactions between AGO and PVA, including, Raman spectroscopy, FT‐IR, field emission scanning electron microscopy (FESEM), and energy‐dispersive x‐ray (EDX). The thermal and structural properties have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA)analysis, and a universal testing machine (UTM). The strong H‐bonding interaction between the PVA interface and AGO considerably enhanced interfacial dispersion and adhesion. As a result, the addition of 5 wt% AGO to the PVA polymers significantly improved their mechanical and thermal properties, including tensile strength which rose by 117%, melting temperature ( T m ) by 7.02°C, and crystallization temperature ( T c ) by 9.06°C. The thermal decomposition temperatures such as T 5% , T 10% and T 50% were increased by 53.68°C, 68.49°C, and 57.37°C, respectively. The results show that a small loading of nanofillers causes substantial increases in the thermal and mechanical properties of PVA, thus making it a promising material for structural applications.

Ultra-Strong, Ultra-Tough, Transparent, and Sustainable Nanocomposite Films for Plastic Substitute

Bionic artificial penile Tunica albuginea

Physically crosslinked poly(vinyl alcohol) gels are versatile biomaterials due to their excellent biocompatibility. In the past decades, physically crosslinked poly(vinyl alcohol) and poly(vinyl alcohol)-based hydrogels have been extensively studied for biomedical applications. However, these materials have not yet been implemented due to their mechanical strength. Physically crosslinked poly(vinyl alcohol) gels consist of a swollen amorphous network of poly(vinyl alcohol) physically crosslinked by microcrystallites. Although the mechanical properties can be improved to some extent by controlling the distribution of microcrystallites on the nano- and micro-scales, enhancing the mechanical properties while maintaining high water content remains very difficult. It may be technologically impossible to significantly improve the mechanical properties while keeping the gel's high water absorbance ability using conventional fabrication methods. Physical and chemical understandings of the swelling and mechanical properties of physically crosslinked poly(vinyl alcohol) gels are considered here; some promising strategies for their practical applications are presented. This review focuses more on the recent studies on swelling and mechanical properties of poly(vinyl alcohol) hydrogels, prepared using only poly(vinyl alcohol) and pure water with no other chemicals, as potential biomedical materials.

The effect of molecular weights and hydrolysis degrees (HD) of polyvinyl alcohol (PVA) on thermal and mechanical properties and crystallinity of polylactic acid (PLA)/PVA blends was investigated. Blends were prepared by the melt blending method using PLA/PVA ratios: 80/20, 90/10 and 97/3 wt. %. A single glass transition temperatures was observed for all PLA/PVA blends, suggesting the formation of binary compatible blends at concentration range studied. Thermogravimetric analysis results showed a better thermal stability for PLA/PVA blends containing PVA of higher Mw and HD. According to mechanical properties, low quantities of PVA (3 wt. %) do not affect the tensile strength of blends (irrespective of Mw and HD). However, as the PVA content increases, tensile strength tends to lower values, especially for blends with 20 wt.% of PVA, with 98% of HD.

The aim of this work was to fabricate the nanocomposite films based on poly(vinyl alcohol) and investigate their thermal stability, mechanical and optical properties of nanocomposite films. For this purpose, first, the titanium dioxide nanoparticles surface was modified simultaneously with biocompatible citric acid and vitamin C to prevent their agglomeration in the poly(vinyl alcohol)matrix. Afterward, the modified titanium dioxide nanoparticles were embedded into the poly(vinyl alcohol)matrix via solution casting along with ultrasonic method. The prepared nanocomposite films were characterized by different analyses such as Fourier transform infrared, X-ray diffraction and thermal gravimetric analysis. Fourier transform infrared emphasized the presence of citric acid and vitamin C on the titanium dioxide surface as well as their interaction with nanoparticles. Poly(vinyl alcohol) nanocomposites thermal degradation temperature increased by 100℃, tensile strength 300% and E-modulus 200%.

The goal of this study was to develop pregelatinized starch (P-St) and polyvinyl alcohol (PVOH) fi lms as water-soluble laundry plastic bags to avoid having contact with COVID-19 infected clothes by extrusion method. The effects of pregelatinized starch (P-St) content on the properties of polyvinyl alcohol (PVOH) fi lms were examined. PVOH and P-St blend were compounded by twin- screw extruder with various P-St content of 0, 10, 20, 30, and 40% by weight with fi xed glycerol content of 20 phr. The blend fi lms were produced by blown fi lm extrusion. The chemical structure, thermal properties, water-solubility, mechanical properties, and the cross-sections morphological properties of PVOH/G/P-St were characterized. As a result, the formation of intermolecular interactions between PVOH, glycerol and P-St was confi rmed by FTIR. Moreover, the addition of P-St on PVOH could reduce the thermal stability due to the content of P-St with amylose, a substance of amorphous structure, affecting the chains fl exibility of PVOH/G/P-St. From the differential scanning calorimeter result, the glass transition temperature was increased with the increment of P-St content because the chains entanglement between PVOH and P-St had affected the reduction in crystallinity and led to the decrement of the melting temperature. Furthermore, the water solubility would strongly be dependent on the percentage of the gelatinized starch (%GS). The solubility decreased as the percentage of the GS increased. In addition, PVOH with 20% of P-St fi lm possessed the highest value in tensile strength and modulus, and the particles of P-St have a good distribution in PVOH/G indicating to stronger interaction of P-St and PVOH/G.

Composite films containing poly(vinyl alcohol) filled with different amounts of graphene oxide (2 and 4 wt%) were prepared by the solution casting technique, and the mechanical properties of the resulting materials were modified with different amounts of glycerol as a plasticizer. Two series of pure poly(vinyl alcohol) and graphene oxide-loaded films with fixed amounts of water were used for modification with glycerol, since water can also serve as a plasticizer for poly(vinyl alcohol). The morphology and physical properties of the plasticized and non-plasticized composites were studied; tensile tests were performed to investigate and compare their mechanical properties. Glycerol addition does not affect the excellent compatibility of the filler with the polymer matrix and uniform distribution of graphene oxide in poly(vinyl alcohol). For poly(vinyl alcohol)/graphene oxide films an increase of the Young's modulus and yield stress was found with an increase of the filler content; the Young's modulus for poly(vinyl alcohol) filled with 4 wt% of graphene oxide is almost two times higher than that of the pure polymer. Simultaneously, a sharp decrease of the elongation at break from 80% for pure PVA to about 5% for the PVA/GO composite with 4 wt% of GO is observed, and the film's brittleness dramatically increases. It was shown that the addition of glycerol to the composite films leads both to the Young's modulus decrease and tensile energy at break increase; here the Young's modulus decreases by 18 times after addition of 20 wt% of glycerol to the poly(vinyl alcohol) film filled with 4 wt% of graphene oxide. Thus, the use of plasticizer results in a significant increase of the ductile properties of graphene oxide filled poly(vinyl alcohol) composite films, and the higher the water content in the composite film, the more drastic the increase of the ductile properties observed.

In this investigation, nanocomposite films were fabricated by dispersion of poly(amide–imide)/CuO nanocomposites as nanofiller in the poly(vinyl alcohol) matrix via an ultrasonic process. The nanofiller was prepared and mixed with PVA matrix. After dispersion of nanofiller into the poly(vinyl alcohol), the mechanical properties of the nanocomposites were improved. For example, the addition of 6 wt% nanofiller into the poly(vinyl alcohol) matrix enhanced the tensile modulus by 39%. The residual weight at 800°C was 7% for pure poly(vinyl alcohol) while the nanocomposites illustrated 12–19% residue at this temperature.

Poly(vinyl alcohol) is one of the most attractive polymers with a wide range of uses because of its water solubility, biocompatibility, low toxicity, good mechanical properties, and relatively low cost. This review article focuses on recent advances in poly(vinyl alcohol) electrospinning and summarizes parameters of the process (voltage, distance, flow rate, and collector), solution (molecular weight and concentration), and ambient (humidity and temperature) in order to comprehend the influence on the structural, mechanical, and chemical properties of poly(vinyl alcohol)-based electrospun matrices. The importance of poly(vinyl alcohol) electrospinning in biomedical applications is emphasized by exploring a literature review on biomedical applications including wound dressings, drug delivery, tissue engineering, and biosensors. The study also highlights a new promising area of particles formation through the electrospraying of poly(vinyl alcohol). The limitations and advantages of working with different poly(vinyl alcohol) matrices are reviewed, and some recommendations for the future are made to advance this field of study.

ABSTRACTThis study aimed to investigate the effect of poly(vinyl alcohol) (PVA) polymer on the thermal, mechanical, and surface properties on cementitious composites for sustainable development. Thermal properties of the PVA‐modified cement paste, including thermal insulation and energy absorption ability, were first studied and correlated with the porosity and microstructures. The experimental results indicated that the thermal conductivity of cement paste can be greatly reduced by 42.9% with 2.0 wt % addition of PVA due to the more porous structure. However, at the same time, more thermal energy can be captured and concentrated at the surface of cement paste with the increasing amount of PVA, causing an increased thermal load and a negative effect on thermal insulating efficiency of cement paste. The contradictory effect of PVA on thermal properties of cement paste should be balanced before it is used as a foaming modifier to fabricate cementitious composites with thermal insulation. In addition, the contact angle measurement revealed that PVA can be used as an effective additive to improve the hydrophobicity of cement‐based materials. Only 3.0% PVA can turn the surface nature from hydrophilicity to hydrophobicity for cement paste, which benefited to the development of self‐cleaning cementitious composites. Finally, the mechanical properties of the PVA‐modified cement paste, especially for the tensile strength that has been rarely reported, were investigated and correlated with its thermal and surface properties. Due to the compensative effects of irregular packing, formation of PVA films and microcracks, tensile strength of cement paste can be improved by 23.5% with a small scarifying of the compressive strength by adding 2.0% of PVA. In conclusion, the PVA‐modified cement‐based materials with lower thermal conductivity, hydrophobic surface nature and enhanced mechanical properties have a great potential to satisfy the high requirements in developing sustainable infrastructure. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46177.

<abstract> Poly(vinyl alcohol) is a water soluble hydrophilic synthetic polymer. As a matrix it can be mixed with fillers having nano dimensions to form polymer nanocomposites with interesting properties, different than those of PVA. From the chemical point of view nanofillers can be elements such as Au, Ag, Se, oxides such as CuO, SrO, TiO₂, graphene oxide, minerals like hallosite, montmorillonite, tubes such as carbon nanotubes, hallosite nano tubes, etc. As presented in this review, some of the nanofillers are able to change and improve poly(vinyl alcohol)'s mechanical, thermal, and electrical properties, and can find uses in medicine. In the latter, due to the fact that poly(vinyl alcohol) is biocompatible, biodegradable, and bioabsorbant, it is possible to produce poly(vinyl alcohol) nanocomposites to be used like antibacterial, tissue engineering, drug carrier, wound dressing, etc. The present article retains the most recent (2019–2020) studies done on poly(vinyl alcohol) nanocomposites structure and contributions to engineering and medicine. </abstract>

Good dispersion of poly(δ-gluconolactone)-grafted graphene in poly(vinyl alcohol) for significantly enhanced mechanical strength