Preparation and characterization of films based on crosslinked blends of gum acacia,polyvinylalcohol, and polyvinylpyrrolidone-iodine complex

In an attempt to develop iodine-release systems based on polymeric blend for biomedical applications, our research group prepared blends of gum acacia (GA), polyvinylalcohol (PVA), and polyvinylpyrrolidone-iodine (PVP-I) complex. The blends of GA/PVA and GA/PVA/PVP-I prepared from the aqueous solutions of the polymers were crosslinked with glutaraldehyde to increase the water resistance of the films and to improve their thermal and mechanical properties. The crosslinked GA/PVA and GA/PVA/PVP-I blend films were characterized by FTIR spectroscopy, DSC, and TGA. The swelling behavior of the prepared blends was investigated and crosslinked GA/PVA blend films were found to be pH sensitive. The properties of PVP-I containing blends differed from those prepared without it probably due to the formation of an intermolecular interaction between PVP-I and the hydroxy-polymers. The results indicated that after crosslinking the blends showed improvement in water resistance, thermal, and mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel bionanocomposites of poly(vinyl alcohol) and modified chiral layered double hydroxides: Synthesis,properties and a morphological study

The effect of novel modified layered double hydroxides (LDHs) on thermal and structural properties of poly(vinyl alcohol) (PVA) was investigated. Organically modified chiral LDH was prepared via ion exchange reaction of LDH in a solution of N,N′-(pyromellitoyl)-bis-l-phenylalanine diacid in distilled water. The modified Mg-Al LDH materials showed an increase in interlayer distance as compared to the unmodified Mg-Al LDH by X-ray diffraction (XRD). Bionanocomposites of PVA with the modified chiral LDH were prepared with different compositions of LDH by solution-intercalation method using the ultrasound-assisted technique. The effect of LDH contents on thermal, physicomechanical, and morphological properties of PVA films was investigated using XRD, Fourier transform infrared, thermogravimetric analysis (TGA), field emission scanning electron microscopy and transmission electron microscopy techniques. The TGA of the obtained bionanocomposites showed an increase in thermal stability. The uniform distribution of clay due to the intimate interaction between clay and polymer appeared to be the reason for the improved properties.     

Dynamic–Mechanical Properties of Bioartificial Polymeric Materials

Bioartificial polymeric materials represent a new class of polymeric materials based on blends of synthetic and natural polymers, designed with the purpose of producing new materials with enhanced properties with respect to the single components. The mechanical properties of bioartificial materials prepared using poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) as synthetic components, and collagen (SC), gelatin, starch, hyaluronic acid (HA) and dextran as biological components, were investigated by dynamic mechanical thermal analysis. The materials were prepared in the form of films or hydrogels and treated by glutaraldehyde (GTA) vapour or thermal dehydration in order to reduce their solubility in water. The results indicate that SC/PVA, gelatin/PVA and starch/PVA films behave as biphasic systems, showing good mechanical properties over a wide range of temperature. It was observed that the GTA procedure affects only the biological component of the SC/PVA and gelatin/PVA blends, whilst the thermal treatment influences mainly the synthetic polymer. In the case of HA/PVA hydrogels, a modulus variation was found with the HA content related to the organization degree and perfection of the PVA network structure. It seems evident that, in the experimental conditions used, dextran/PAA mixtures behave as miscible blends showing a glass transition intermediate between those of the pure components. With both untreated and GTA-treated gelatin/PMAA blends, it was not possible to evaluate the miscibility of the systems; it could only be affirmed that these materials show good mechanical properties over a wide range of temperature. © 1997 SCI.     

Impact of nanoclay on physicomechanical and thermal analysis of polyvinyl alcohol/fumed silica/clay nanocomposites

Polyvinyl alcohol (PVA)/fumed silica/clay nanocomposites are prepared via solution intercalation by exploiting phase separation based on the bridging of particles by polymer chains. PVA/fumed silica/clay nanocomposites are characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and thermogravimetric analysis. Mechanical properties are determined by universal testing machine. From FTIR results, it indicates that IR spectrum for PVA/fumed silica/clay nanocomposites, especially PVA/fumed silica/clay (1.30E) nanocomposites, is much broader than pure PVA and other clay nanocomposites. The better interfacial bonding between PVA/fumed silica/clay (1.30E) nanocomposites are reflected in the improvement of the mechanical properties as well as thermal stability. The surface area analysis result proves that the PVA/fumed silica/clay (1.30E) nanocomposites have higher surface area and pore volume with less pore size. With the addition of 1.30E clay to the composite system, the tensile strength and modulus had shown the highest values as well as higher activation energy for thermal decomposition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41843.     

Poly(vinyl alcohol) nanocomposite films: Thermooptical properties,morphology, and gas permeability

Poly(vinyl alcohol) (PVA)/saponite nanocomposites were prepared with various clay concentrations with the solution intercalation method. The intercalations of the polymer chains in the clay were examined with wide‐angle X‐ray diffraction and transmission electron microscopy. The variations of the dispersion, morphology, thermal properties, and gas permeability of the nanocomposites with clay concentrations in the range of 0–10 wt % were examined. Up to a 5 wt % clay loading, the clay particles were highly dispersed in the PVA matrix without any agglomeration of particles. However, some agglomerated structures formed in the polymer matrix above a 7 wt % clay concentration. The thermal stability of the hybrids increased linearly with increases in the clay loading up to 10 wt %. To measure the oxygen permeability and optical properties of the PVA hybrid films, the PVA hybrid solutions were coated onto both biaxially oriented polypropylene and poly(ethylene terephthalate) films, which were used as polymer substrates. The oxygen permeability values monotonically decreased with increases in the clay loading in the range of 0–10 wt %. The optical properties, such as the haze and gloss of the hybrid films when coated onto the matrix films, were nearly constant, that is, independent of the clay loading. These improvements arose because of the largely nanometer‐scale dispersion of the clay layers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 591–596, 2006     

Electron beam synthesis and characterization of poly(vinyl alcohol)/montmorillonite nanocomposites

Poly(vinyl alcohol) (PVA)/montmorillonite clay (MMT) nanocomposites in the form of films were prepared under the effect of electron beam irradiation. The PVA/MMT nanocomposites gels were characterized by X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and mechanical measurements. The study showed that the appropriate dose of electron beam irradiation to achieve homogeneous nanocomposites films and highest gel formation was 20 kGy. The introduction of MMT (up to 4 wt %) results in improvement in tensile strength, elongation at break, and thermal stability of the PVA matrix. In addition, the intercalation of PVA with the MMT clay leads to an impressive improved water resistance, indicating that the clay is well dispersed within the polymer matrix. Meanwhile, it was proved that the intercalation has no effect on the metal uptake capability of PVA as determined by a method based on the color measurements. XRD patterns and SEM micrographs suggest the coexistence of exfoliated intercalated MMT layers over the studied MMT contents. The DSC thermograms showed clearly that the intercalation of PVA polymer with these levels of MMT has no influence on the melting transitions; however, the glass transition temperature (T_g) for PVA was completely disappeared, even at low levels of MMT clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1129–1138, 2006     

Improvement of polyvinyl alcohol/casein blend film properties by adding cellulose nanocrystals

This study aims to prepare and examine the properties of poly(vinyl alcohol)/casein (PVA/CAS) based films reinforced with cellulose nanocrystals (NC), which can be presented as an alternative to petroleum-based polymer packaging materials. PVA/CAS and 0.5–1–3–5 wt% NC containing PVA/CAS biocomposite films were prepared by solution casting method. Afterward, the 1NC film, which exhibited the best mechanical properties, was crosslinked with various amounts of glyoxal. Structural, morphological (polarized optical microscope), mechanical (tensile), thermal (differential scanning calorimetry, thermogravimetric analysis), contact angle, and water vapor transmission rate (WVTR) properties of the samples were investigated. The 1NC film exhibited the highest tensile strength (TS) and elongation values in PVA/CAS/NC films, and its mechanical properties decreased due to agglomeration with increasing NC amount. As expected, crosslinking improved the TS. The thermal stability of the PVA/CAS film was generally improved with the addition of NC and crosslinking. The high WVTR value of the PVA/CAS film decreased with the addition of NC and the 1NC film presented the lowest value. Thanks to the complex structure formed as a result of crosslinking and the reduced free volume, the WVTR of the 1NC film has reduced. The results showed that PVA/CAS-based films with good mechanical properties and water vapor barrier are promising as packaging materials.     

Nanofibrillated cellulose,poly(vinyl alcohol), montmorillonite clay hybrid nanocomposites with superior barrier and thermomechanical properties

Nanocomposites of poly(vinyl alcohol) (PVA), nanofibrillated cellulose (NFC), and montmorillonite (MMT) clay were prepared via solvent casting. In addition to investigating the effect of clay loading, PVA matrices crosslinked with poly(acrylic acid) (PAA) were prepared and compared with linear (noncrosslinked) PVA nanocomposites. ¹³C NMR and infrared spectroscopy confirmed the presence of crosslinks. Scanning electron microscopy revealed effective NFC and MMT clay dispersion throughout the nanocomposites, while X‐ray diffraction highlighted the effectiveness of PAA to encourage clay dispersion. MMT clay provided a barrier against the diffusion of water and oxygen (molecules) through the nanocomposite films. Permeability and adsorption were further reduced by crosslinking, while oxygen barrier properties were remarkably enhanced at elevated relative humidities. Thermal stability of the PVA segments was strengthened by the presence of MMT clay and crosslinks. MMT clay–reinforced PVA and NFC within the films, increasing the Young's modulus, tensile strength, and glass transition temperature. Crosslinking further enhanced the thermomechanical properties by imparting physical restraints on polymer chain segments, providing elasticity, and ductility. The hybrid films were successfully reinforced at elevated humidities, with nanocomposites displaying enhanced storage moduli and near‐complete recovery. POLYM. COMPOS., 35:1117–1131, 2014. © 2013 Society of Plastics Engineers     

Influences of Functionalized Nanoclays on Morphology and Mechanical Properties of Polyvinyl Alcohol-Based Composites by Twin-Screw Extruder

Polyvinyl alcohol-based nanocomposites filled with different weight percentage of functionalized nanoclays were prepared by melt processing with a twin-screw extruder. The effective incorporation of amine-modified bentonite nanoclays in the PVA matrix leads to the increase in thermal stability, stress–strain properties. The effect of the addition of functionalized nanoclays in PVA matrix exhibits intercalated nanocomposite structure. The thermal decomposition (T_d) temperature of the composites increases up to 30°C, than pristine PVA. The morphology influences were studied by TEM. These clay nanocomposite films could be useful for wound dressing material and for enhancing the moisture absorbance properties.     

Preparation and properties of poly(vinyl alcohol)-clay nanocomposite materials

A series of polymer-clay nanocomposite (PCN) materials that consist of poly(vinyl alcohol) (PVA) and layered montmorillonite (MMT) clay are prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic PVA matrix via an in situ free radical polymerization with AIBN as initiator. Organic vinyl acetate monomers are first intercalated into the interlayer regions of organophilic clay hosts and followed by a one-step free radical polymerization. The prepared poly(vinyl acetate)-clay (PVAc-clay) solution are then saponified via direct-hydrolysis with NaOH solution to form PVA-clay nanocomposite materials. The as-synthesized PCN materials are typically characterized by Fourier-Transformation infrared (FTIR) spectroscopy, wide-angle X-ray diffraction and transmission electron microscopy.The molecular weights of poly(vinyl alcohol) (PVA) extracted from polymer-clay nanocomposite (PCN) materials and bulk PVA are determined by gel permeation chromatography (GPC) analysis with THF as eluant. The viscosity property of PCN materials with different feeding amount of MMT clay is studied by an ubbelohode capillary viscometer. The morphological image of as-synthesized materials is studied by scanning electron microscopy (SEM) and optical polarizing microscope (OPM). Effects of the material composition on the thermal stability, mechanical strength, optical clarity of PVA along with a series of PCN materials, in the form of fine powder and free-standing film, are also studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analyzer (DMA) and UV-visible transmission spectra, respectively.     

Dual‐bonding structured ternary composite film of poly(vinyl alcohol)–boric acid–nanodiamond

Ternary composite films of poly(vinyl alcohol) (PVA), boric acid (BA), and detonation nanodiamond (DND) were prepared by aqueous solution method. Because of its excellent mechanical/thermal properties and low friction coefficient, DND is expected to offer PVA film superior performance if the puzzles of particle agglomeration in polymer matrix and fragile interface reaction between DND and PVA can be settled. BA was used as a crosslinking agent to form a strong network structure between DND and PVA. Investigation on microstructure of PVA/BA/DND films and bonding mechanisms therein shows that BA, DND, and PVA may crosslink by oxo‐bridges owing to the interaction of hydroxyl groups. The Young's modulus (E) of composite films was enhanced by nearly 3.3 times with only 0.8 wt % DND loading, and the antiwear, thermal stability, and waterproof properties can be significantly improved after the crosslinking. Meanwhile, the transparency of composite films can be well preserved even with large DND content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45449.     

淀粉/三聚氰胺增塑PVA熔融加工膜的制备及性能

以淀粉/三聚氰胺为复配增塑剂,利用熔融加工工艺制备聚乙烯醇(PVA)膜,采用差示扫描量热(DSC)、热失重分析(TG)和力学性能测试等考察了增塑剂含量对PVA膜性能的影响.结果表明,复配增塑剂能有效破坏分子链间氢键,对PVA的增塑作用明显.随增塑剂含量增大,PVA膜的力学性能和熔体质量流动速率呈先增大后减小的趋势,熔点...     

Preparation and characterization of LDPE/PVA blend films filled with glycerin‐plasticized polyvinyl alcohol

A series of LDPE/PVA blend films were prepared via a twin‐screw extruder, and their morphology, thermal property, oxygen and water vapor permeation, surface properties, and mechanical properties were investigated as a function of the PVA content. During the extrusion process of the blend films, glycerin improved the compatibility and processing conditions between LDPE and PVA. The melting temperature (T_m), melting enthalpy (ΔH_m), crystallinity (%), and thermal stability of the thermal decomposition temperature (T_5%) of the LDPE/PVA blend films decreased with increasing PVA content. The oxygen permeabilities of the blend films decreased from 24.0 to 11.4 cm³·cm (m²·day·atm)^?1 at 23°C. The WVTR increased from 7.8 to 15.0 g(m² day)^?1 and the water uptake increased from 0.13 to 9.31%, respectively. The mechanical properties of blend films were slightly enhanced up to 2% PVA and then decreased. The physical properties of the blend films strongly varied with the chemical structure and morphology depending on the PVA and glycerin. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41985.     

快速吸水响应性PVA/HEC多孔复合材料的制备及性能

将酵母菌作为微生物发泡剂引入到聚乙烯醇(PVA)/羟乙基纤维素(HEC)复合材料中,结合循环冷冻-解冻法制备PVA/HEC多孔复合材料。测试不同实验条件PVA/HEC多孔复合材料的孔隙率、吸水性、保水性。通过FTIR和SEM表征样品的微观结构;采用热重分析仪(TG)、X射线衍射(XRD)仪、万能拉力试验机分析样品热稳定性、结晶性、力学性能。结果表明：酵母菌发泡PVA/HEC多孔复合材料孔呈大孔套小孔的椭圆状开孔结构,吸水响应速率快。保水性良好,24h后保水率降至最低。与未经酵母菌发泡的PVA/HEC复合材料相比,酵母菌发泡PVA/HEC多孔复合材料热稳定性和力学性能均有所提高,压缩强度和极限抗压应力分别是13.2、6.4MPa。     

快速吸水响应性PVA/HEC多孔复合材料的制备及性能

将酵母菌作为微生物发泡剂引入到聚乙烯醇(PVA)/羟乙基纤维素(HEC)复合材料中,结合循环冷冻-解冻法制备PVA/HEC多孔复合材料。测试了不同实验条件下PVA/HEC多孔复合材料的孔隙率、吸水性、保水性。通过FTIR和SEM表征样品的微观结构;采用热重分析仪(TG)、X射线衍射仪(XRD)、万能拉力试验机分析样品热稳定性、结晶性、力学性能。结果表明:酵母菌发泡PVA/HEC多孔复合材料孔呈大孔套小孔的椭圆状开孔结构,具有快速吸水响应性;保水性良好,24 h后保水率降至最低;与PVA/HEC复合材料相比,PVA/HEC多孔复合材料热稳定性和力学性能均有所提高,压缩强度和极限抗压应力分别是13.2、6.4 MPa。     

聚乙烯醇/凹凸棒黏土纳米复合膜的制备及其性能

以聚乙烯醇(PVA)和提纯凹凸棒黏土(APT)为原料,采用溶液流延成膜法,制备了系列不同APT含量的PVA/APT纳米复合膜。采用XRD、FTIR和SEM对复合膜的结构进行了表征,测试了复合膜的热性能、力学性能和耐水性能。结果表明,APT可均匀分散在PVA基体中,APT的加入使得PVA的结晶度有所下降但并未改变其晶型。APT与PVA通过氢键作用,改善了复合膜的热稳定性、力学性能和耐水性。当APT含量为4%时,纳米复合膜有最优的性能。     

Comparison of the clay minerals type on the properties of reinforced‐PVA nanocomposites

The aim of this study is to determine and compare the effect of the clay minerals in a clay–polymer nanocomposite concerning the mechanical and thermal properties. The effects of the different clay minerals on different polymers have been researched frequently, but the comparison of the clay minerals was never studied. Since clay minerals have different properties from each other such as surface area, crystal structure, and surface properties, the effect of the clay minerals on the nanocomposites would be different. In this study, montmorillonite (Mt), vermiculite (Verm), and sepiolite (Sep) clay minerals were used to prepare the nanocomposites for the comparison. A basic polymer, polyvinyl alcohol (PVA), was chosen as the polymer and the basic method, solution‐casting method, was used to prepare the nanocomposites. The structural and morphological characterizations were examined using X‐ray diffraction, transmission electron microscopy, and Fourier transform infrared techniques, and mechanical and thermal properties of the nanocomposites were determined by dynamical mechanical analysis, and differential scanning calorimetry methods. The results showed that the layered clay minerals Mt and Verm can be dispersed well in the polymer and improved the mechanical and thermal properties more than the fibrous Sep. The bigger surface area of Verm lead to higher values of the elastic modulus, while the more interaction between Mt and PVA lead to higher values of glass temperature. POLYM. COMPOS., 38:1698–1704, 2017. © 2015 Society of Plastics Engineers     

Studies on the properties of poly(vinyl alcohol) film plasticized by urea/ethanolamine mixture

This study investigated the effects of urea/ethanolamine mixture (UE) on the crystallinity, thermal, and mechanical properties of poly(vinyl alcohol) (PVA) films. PVA films were prepared from solutions containing PVA, urea, ethanolamine, and water by casting and evaporating at 50°C for 12 h. The plasticization efficiency of UE was compared with that of glycerol (GL), the conventional plasticizer for PVA. The properties of PVA films plasticized by UE and GL, abbreviated to UE-plasticized PVA film and GL-plasticized PVA film, respectively, were investigated by Fourier-transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and mechanical testing. It was proved that UE could form more stable hydrogen bonding with the hydroxyl group of PVA molecule and was more effective in breaking the hydrogen bonds between the hydroxyl groups. Thus, the crystallinity of UE-plasticized PVA films was lower than that of GL-plasticized PVA films. The melting temperatures of UE-plasticized PVA films were lower than those of GL-plasticized PVA films. It was found that UE-plasticized PVA film showed a higher degradation temperature compared with GL-plasticized PVA film. The degree of swelling of UE-plasticized PVA film was higher than that of GL-plasticized PVA film but solubility (S) of UE-plasticized PVA film was lower in aqueous solution. Furthermore, UE-plasticized PVA films show lower tensile strength and higher elongation at break (E) than those of GL-plasticized PVA films. The tensile strength, E, and Young's modulus of PVA film containing 30% UE mixture reached 50.78 MPa, 591.19% and 76.9 MPa, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of PAM/PVA blending films by solution-cast technique and its characterization: a spectroscopic study

Polyacrylamide (PAM) and poly(vinyl alcohol) (PVA) were blended with different weight percentages (70/30, 50/50, 30/70) using solution-cast technique. The prepared films were studied by different characterization techniques. The effect of PVA content on PAM blends was investigated by Fourier transform infrared (FTIR), ultra violet visible (UV–vis), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Different mechanical properties of blends were also studied. Significant changes were observed in FTIR, UV–vis, TGA, SEM and mechanical analysis which revealed interactions between the two polymers. FTIR spectra showed the presence of hydrogen bonding between PAM and PVA and hydrophilic nature of the blends. Different optical properties were studied by UV–vis spectroscopy. The weight loss, as a function of temperature of blends, was analyzed by TGA. The results obtained from different experimental techniques were supported by SEM image analysis. FTIR analysis confirmed the conclusion on the specific hydrogen bonding between –CONH₂ groups in PAM and –OH group in PVA. These results showed the change in the thermal stability and mechanical properties. FTIR analysis revealed that a blend ratio of 50/50 wt% had maximum intermolecular interaction between two polymers. It was finally concluded that blend films with the above ratio display higher thermal stability and improved mechanical properties. Due to changes in interactions, the optical parameters were also changed.     

A chitosan/poly(vinyl alcohol) nanocomposite film reinforced with natural halloysite nanotubes

Biodegradable polymer/clay nanocomposites have attracted tremendous attentions because of their excellent properties and ecofriendly advantages. In this article, a series of nanocomposite films were prepared by introducing of halloysite nanotubes (HTs) into chitosan (CS)/poly(vinyl alcohol) (PVA) matrix using the solution casting method, and the effect of HT as nanofillers on the properties of polymer/HT nanocomposites was explored. The results indicated that the tensile strength of CS/PVA/HT3 and elongation at break of CS/PVA/HT2 sharply increased by 39.72% and 26.14% in comparison with the pure CS/PVA film, respectively. The water resistance and thermal stability of polymer/HT nanocomposites were also improved compared with the pure CS/PVA film, but the optical property of the nanocomposite films was not affected by introducing HT into the CS/PVA matrix. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers