Physical properties of PVA doped with algal glycerol

Physical behavior of membrane blends of poly(vinyl alcohol) (PVA) doped with different weight percentage (wt %) of algal glycerol is reported. Solid‐state PVA/glycerol membranes were prepared by the solution casting method. Electrical impedance measurements were conducted to test the effect of varying the percentage of glycerol on the conductivity of the membranes. The measurements were made in the frequency and temperature ranges 1 Hz–1 MHz and 303–423 K, respectively. It was observed that the ionic conductivity increased with the increase of glycerol concentration as well as temperature. The thermal properties of the films were characterized. It was found that the thermal properties, particularly the melting point (T_m), for PVA blends exhibit a reduced value proportional to the algal glycerol content. Fourier transform infrared spectroscopy was utilized to evaluate the interactions between the glycerol and PVA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4482–4489, 2013     

Novel polymer electrolyte membranes based on semi‐interpenetrating blends of poly(vinyl alcohol) and sulfonated poly(ether ether ketone)

In this work, the properties of novel ionic polymer blends of crosslinked and sulfonated poly(vinyl alcohol) (PVA) and sulfonated poly(ether ether ketone) (SPEEK) are investigated. Crosslinking and sulfonation of PVA were carried out using sulfosuccinic acid (SSA) in the presence of dispersed SPEEK to obtain semi‐interpenetrating network blends. PVA–SSA/SPEEK blend membranes of different compositions were studied for their ion‐exchange capacity, proton conductivity, water uptake, and thermal and mechanical properties. The hydrated blend membranes show good proton conductivities in the range of 10^?3 to 10^?2 S/cm. When compared with pure component membranes, the PVA–SSA/SPEEK blend membranes also exhibit improvement in tensile strength, tensile modulus, and delay in the onset of thermal and chemical degradation. Semi‐interpenetrating nature of the blends is established from morphology and dynamic mechanical analysis. Morphology of the membranes was studied using scanning electron microscopy after selective chemical treatment. The dynamic mechanical properties of the membranes are examined to understand the miscibility characteristics of the blends. The relative proportions of PVA and SPEEK and the degree of crosslinking of PVA–SSA are important factors in determining the optimum properties for the blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of glycerol on thermal and mechanical properties of polyvinyl alcohol/starch blends

The paper reports the results of studies on the effect of glycerol content on thermal, mechanical, and dynamic mechanical properties of blends of starch and polyvinyl alcohol (PVA). Degree of crystallinity of the starch/PVA blends (4 g/4 g ratio) remains almost constant up to 3.78 g of glycerol as determined by differential scanning calorimetry (DSC) and x‐ray diffraction studies. At higher loading of glycerol the crystallinity decreases. DTG thermograms revealed occurring of one maximum degradation temperature closer to that of starch in blends containing up to 3.78 g of glycerol. At higher glycerol content there gradually occur two distinct peaks of maximum degradation temperature, one occurring close to that of starch and other occurring close to the PVA peak, indicating phase separation of the blend components. Results of stress–strain studies indicate lowering of tensile properties and energy at break particularly at higher glycerol content (beyond 3.78 g). Dynamic mechanical studies reveal a sharp drop in dynamic modulus at higher glycerol content at all temperatures. The blend with low glycerol content shows transitions of starch, while the blend containing high glycerol content beyond 3.78 g display the transitions due to both starch and PVA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal,mechanical, and surface characterization of starch–poly(vinyl alcohol) blends and borax‐crosslinked films

Starch–poly(vinyl alcohol) (PVA) blends with different compositions were prepared and crosslinked with borax by in situ and posttreatment methods. Various amounts of glycerol and poly(ethylene glycol) with a molecular weight of 400 were added to the formulations as plasticizers. The pure starch–PVA blends and the crosslinked blends were subjected to differential scanning calorimetry, thermogravimetry, and X‐ray photoelectron spectroscopic studies. Broido and Coats–Redfern equations were used to calculate the thermal decomposition kinetic parameters. The tensile strengths and elongation percentages of the films were also evaluated. The results suggested that the glass‐transition temperature (T_g) and the melting temperature strongly depended on the plasticizer concentration. The enthalpy relaxation phenomenon was dependent on the starch content in the pure blend. The crosslinked films showed higher stability and lower T_g's than pure PVA and starch–PVA blends, respectively. High‐resolution X‐ray photoelectron spectroscopy provided a method of differentiating the presence of various carbons associated with different environments in the films. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1313–1322, 2005     

The effect of poly(ethylene glycol) as plasticizer in blends of poly(lactic acid) and poly(butylene succinate)

The effect of polyethylene glycol (PEG) on the mechanical and thermal properties of poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) blends was examined. Overall, it was found that PEG acted as an effective plasticizer for the PLA phase in these microphase‐separated blends, increasing the elongation at break in all blends and decreasing the T_g of the PLA phase. Significant effects on other properties were also observed. The tensile strength and Young's modulus both decreased with increasing PEG content in the blends. In contrast, the elongation at break increased with the addition of PEG, suggesting that PEG acted as a plasticizer in the polymer blends. Scanning electron microscope images showed that the fracture mode of PLA changed from brittle to ductile with the addition of PEG in the polymer blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43044.     

Super‐tough biodegradable poly(vinyl alcohol)/poly(vinyl pyrrolidone) blends plasticized by glycerol and sorbitol

Tough biodegradable films were prepared using a poly(vinyl alcohol) (PVA)/poly(vinyl pyrrolidone) (PVP) (1:1) blend with plasticizers of glycerol (GLY), sorbitol (SOR), and their (one to one) mixture. We studied the effect of plasticization on the structural, thermal, and mechanical properties of the PVA/PVP blend films. Fourier transform infrared spectra indicated good miscibility of the two components due to the H‐bonding between the PVA and PVP molecules. The addition of plasticizers reduced the interaction between PVA and PVP, evidenced by an increase in the intensity of PVA diffraction peaks observed in the X‐ray diffraction (XRD) characterization. Thermal degradation of the blends increased as a function of the plasticizer used. GLY affected thermal degradation more than SOR and the mixtures. The incorporation of the plasticizers promoted the growth of PVA crystals as evidenced by XRD patterns and the enthalpy of fusion (ΔH_f) obtained by differential scanning calorimetry measurements. The introduction of SOR to the binary blend increased toughness seven times and imparted simultaneous and pronounced improvements to maximum tensile stress and elongation at break. This behavior holds out great promise for the development of a new generation of mechanically robust, yet thoroughly biodegradable materials that could effectively supplant conventional polymers in demanding applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46406.     

The effect of citrate ester plasticizers on the thermal and mechanical properties of poly(DL‐lactide)

Citrate esters triethyl citrate, tributyl citrate, and acetyl tributyl citrate were used as plasticizers for amorphous poly(D,L ‐lactide) (PDLLA). The resultant compositions were analyzed by means of differential scanning calorimetry (DSC), dynamic mechanical thermal analysis, and tensile testing to investigate the properties of the blends. Glass transition temperatures (T_gs) obtained by DSC were also compared to theoretically calculated T_gs. Increasing plasticizer content decreased the resultant T_g of the blend with plasticizer efficiency enhanced as the molecular weight of the citrate ester increased. However, in blends with high plasticizer content, a lack of miscibility also occurred with increased molecular weight. Theoretical results were comparable with those obtained experimentally at compositions, which were miscible. Increasing plasticizer content increased the ductility and decreased the strength of the polymer. The addition of 10 wt % plasticizer to PDLLA decreased tensile strength by over 50% with the deterioration larger at higher concentrations of plasticizer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Miscibility of poly(vinyl alcohol)/polyacrylamide blends before and after gamma irradiation

Films of polymer blends having various contents of poly(vinyl alcohol) (PVA) and polyacrylamide (PAM) were prepared by the solution casting technique using water as a common solvent. The thermal, mechanical and morphological properties of these blends before and after exposure to various doses of gamma radiation, up to 100 kGy, have been investigated. The visual observation and reflectance measurements show that PVA/PAM blends are miscible over a wide range of composition. Moreover, the differential scanning calorimetry (DSC) thermograms show only a single glass transition temperature (T_g), but not those of PVA or PAM homopolymers, giving further support to the complete compatibility of such blends. The T_g of PVA/PAM blends decreases with increasing content of PAM but increases after exposure to gamma irradiation, indicating the occurrence of crosslinking. These findings were demonstrated by the scanning electron micrographs of the fracture surfaces and the tensile mechanical properties. The TGA thermograms and percentage mass loss at different decomposition temperatures show that unirradiated PVA homopolymer possesses higher thermal stability than PAM homopolymer and their blends within the heating temperature range investigated, up to 250 °C. An opposite trend is observed within the temperature range 300–500 °C. In general, the thermal stability of homopolymers or their blends improves slighly after exposure to an irradiation dose of 100 kGy. These findings are clearly confirmed by the calculated activation energies of the thermal decomposition reaction of the homopolymers and the blends. © 2003 Society of Chemical Industry     

The Effect of Epoxidized Sunflower Oil on the Miscibility of Plasticized PVC/NBR Blends

Blends of plasticized poly(vinyl chloride) (PVC) with several ratios of nitrile rubber (NBR) were studied. The effects of epoxidized sunflower oil (ESO) in combination with di-(2-ethylhexyl)phthalate (DEHP) in the PVC blends on the tensile strength, elongation, hardness, and dynamical mechanical analysis (DMA) were studied. The modulus and hardness results revealed that the addition of ESO to the blend favors the miscibility of PVC and NBR. The PVC/NBR/(DEHP-ESO) blends behave as a compatible system as is evident from the single T _g observed in DMA. The moderate level broadening of the T _g zone in blends is due to the presence of ESO in the plasticizer system. Blends of plasticized PVC and nitrile rubber showed promising properties. The ESO is suitable to partially replace DEHP in PVC/NBR blends.     

Electrical properties of sorbitol‐doped poly(vinyl alcohol)–poly(acrylamide‐co‐acrylic acid) polymer membranes

Solid polymer membranes from poly(vinyl alcohol) (PVA) and poly(acrylamide‐co‐acrylic acid) (PAA) with varying doping ratios of sorbitol were prepared using the solution casting method. The films were examined with Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and AC impedance spectroscopy. The impedance measurements showed that the ionic conductivity of PVA–PAA polymer membrane can be controlled by controlled doping of sorbitol within the polymer blends. The PVA–PAA–sorbitol membranes were found to exhibit excellent thermal properties and were stable for a wide temperature range (398–563K), which creates a possibility of using them as suitable polymers for device applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fabrication and properties of clay-supported carbon nanotube/poly (vinyl alcohol) nanocomposites

Clay-supported carbon nanotubes (Cs-CNTs) were used as novel nanofillers to improve the thermal and mechanical properties of a polymer. Cs-CNT/poly (vinyl alcohol) (PVA) nanocomposite films were successfully fabricated, and their relative properties were investigated by using differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. Experimental results showed that the thermal stability and dynamic mechanical properties of PVA were remarkably enhanced by incorporating the Cs-CNTs into PVA matrix. The largest T_g difference of 14°C was obtained between pure PVA and PVA nanocomposite with 7 wt% Cs-CNTs. Moreover, the storage modulus of PVA was significantly improved by 133% at 50°C, when 7 wt% Cs-CNTs was added to PVA matrix. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Mechanical properties,oil resistance,and thermal aging properties in chlorinated polyethylene/natural rubber blends

The use of natural rubber (NR) for partly substituting elastomeric chlorinated polyethylene (CPE) was determined. Mechanical and thermal aging properties as well as oil resistance of the blends were also investigated. The amount of NR in blends significantly affected the properties of the blends. The blends with NR content up to 50 wt % possessed similar tensile strength to that of pure CPE even after oil immersion or thermal aging. Modulus and hardness of the blends appeared to decrease progressively with increasing NR content. These properties also decreased in blends after thermal aging. After oil immersion, hardness decreased significantly for the blends with high NR content, whereas no change in modulus was observed. The dynamic mechanical properties were determined by dynamic mechanical thermal analysis. NR and CPE showed damping peaks at about ?40 and 4 °c, respectively; these values correlate with the glass‐transition temperatures (T_g) of NR and CPE, respectively. The shift in the T_g values was observed after blending, suggesting an interfacial interaction between the two phases probably caused by the co‐vulcanization in CPE/NR blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 22–28, 2002; DOI 10.1002/app.10171     

Thermal,morphological, and physicomechanical properties of (chlorinated polyethylene rubber)/(chloroprene rubber) blends

The effect of the blend ratio on the thermal, morphological, and physicomechanical properties of (chlorinated polyethylene rubber)/(chloroprene rubber) (CPE/CR) blends was studied. Two distinct glass transition temperatures (T_g) of all blends were observed in differential scanning calorimetry curves, falling between the T_g of the two pure rubbers. Analysis of the blends by scanning electron microscopy showed both dispersed and continuous phase morphology that depended on the blend composition. Thermogravimetric analysis showed that all the compounds underwent two stages of thermal degradation. The Mooney viscosity and optimum cure times increased with the increase in CPE contents, whereas the scorch times decreased. The tensile strength and elongation at break decreased, whereas the 100% modulus, hardness, and compression set increased with the increase of CPE content; the tear strength had the lowest value for the 50/50 CPE/CR blend because of the poor miscibility. The results from thermal aging and oil resistance tests showed that pure CPE possessed better thermal aging property and oil resistance than those of pure CR. Thus, considerable improvement in oil resistance of the blend compounds was achieved with the increase of CPE content. J. VINYL ADDIT. TECHNOL., 21:18–23, 2015. © 2014 Society of Plastics Engineers     

Poly(vinyl alcohol)‐g‐lactic acid copolymers and films with silver nanoparticles

Poly(vinyl alcohol) (PVA), a well‐known synthetic biodegradable, biocompatible, and hydrophilic polymer is susceptible to several structural modifications, due to the presence of hydroxyl groups in its backbone. PVA was grafted with L (+)‐lactic acid (LA) in molar ratios VA/LA (1/1, 1.5/1, and 2.2/1), manganese acetate as catalyst, by solution polycondensation procedure, resulting the poly(vinyl alcohol)‐g‐lactic acid copolymers. Aqueous solutions of copolymers with glycerol as plasticizer, silver nanoparticles (Ag^o), and sodium tetraborate as crosslinking agent were used for films casting. The copolymers were characterized by FTIR and ¹H RMN spectroscopy, gel permeation chromatography, thermal analyses (DTG and DSC), silver particles size, while films were characterized by mechanical properties and mechanodynamic analyses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Interfacial modification mechanism of nanocellulose as a compatibilizer for immiscible binary poly(vinyl alcohol)/poly(ethylene oxide) blends

We undertook this study to understand reinforcement mechanism of short cellulose nanocrystals (CNCs) and long cellulose nanofibrils (CNFs) as compatibility agents for improving the interfacial miscibility of poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) blends. The effects of the two cellulose nanofibers on the morphological, mechanical, and thermal properties of the polymer blends were compared systematically. The light transparency, scanning electron microscopy, and Fourier transform infrared results show that nanocellulose between PVA and PEO eliminated the negative effects generated by the immiscible interface through increased hydrogen bonding. Thermogravimetric analysis and differential scanning calorimetry results show that crystalline region reorganization around the interface facilitated the shift of the polymer blends from multiple phases to a homogeneous phase. According to the Halpin‐Kardos and Quali models, we assumed that the potential for repairing the immiscible interface would have a larger effect than the potential of reinforcement. At the same concentration, polymer blends with CNCs showed greater light transparency, strength, modulus, and crystal structure than with those with CNFs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45896.     

Synthesis of starch‐based plastic films by electron beam irradiation

Starch‐based plastic films were prepared by the electron beam irradiation of starch and poly(vinyl alcohol) (PVA) in a physical gel state at room temperature. The influence of starch/PVA composition, irradiation dose, and plasticizer (glycerol) on the properties of the plastic films was investigated. The gel fraction of the starch/PVA films increased with both the radiation dose and PVA content in the plastic film and decreased with increasing glycerol concentration. The starch/PVA compatibility was determined by measurement of the thermal properties of the starch/PVA blends with various compositions with differential scanning calorimetry. The swelling of the starch/PVA films increased with increasing PVA content and decreasing irradiation dose. Mechanical studies were carried out, and the tensile strength of the films decreased at high starch ratios in the starch‐based mixture. This was due to the decrease in the degree of crosslinking of starch. Furthermore, when PVA, a biodegradable and flexible‐chain polymer, was incorporated into the starch‐based films, the properties of the films, such as the flexibility (elongation at break), were obviously improved. The tensile strength of the films decreased with increasing glycerol concentration, but elongation at break increased up to a maximum value at a 20% glycerol concentration, and then, it leveled off and decreased slightly. Biodegradation of the starch/PVA plastic films was indicated by weight loss (%) after burial in soil and morphological shape, which was detected by scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 504–513, 2007     

The Effect of glycerol on the crystalline,thermal, and tensile properties of CaCl2‐doped starch/PVA films

Starch/poly(vinyl alcohol) (PVA) films with the addition of 10 wt% CaCl₂ and various content of glycerol were prepared. The effect of glycerol on the crystalline, thermal, and tensile properties of CaCl₂‐doped starch/PVA films was studied by X‐ray diffraction, thermogravimetric analysis (TGA), and tensile testing, respectively. The effect of glycerol on the miscibility of CaCl₂‐doped starch/PVA films was studied by scanning electron microscopy. The CaCl₂‐doped starch/PVA film became more homogeneous after the addition of glycerol. The addition of glycerol would increase the crystallinity of CaCl₂‐doped starch/PVA film. With the addition of 10 wt% glycerol and 10 wt% CaCl₂, the starch/PVA film showed the highest degree of crystallinity. The TGA results show that the thermal stability of CaCl₂‐doped starch/PVA film increased after the addition of glycerol. The toughness of CaCl₂‐doped starch/PVA films was enhanced with the addition of glycerol. The starch/PVA film with the addition of 10 wt% CaCl₂ and 20 wt% glycerol showed the tensile strength of 17 MPa and the elongation at break of 428%. Moreover, the water sorption of CaCl₂‐doped starch/PVA film decreased after the addition of glycerol at the low and intermediate relative humidity of 33 and 54%. POLYM. COMPOS., 37:3191–3199, 2016. © 2015 Society of Plastics Engineers     

Characterization of linear low‐density polyethylene/poly(vinyl alcohol) blends and their biodegradability by Vibrio sp. isolated from marine benthic environment

Increasing amounts of plastic waste in the environment have become a problem of gigantic proportions. The case of linear low‐density polyethylene (LLDPE) is especially significant as it is widely used for packaging and other applications. This synthetic polymer is normally not biodegradable until it is degraded into low molecular mass fragments that can be assimilated by microorganisms. Blends of nonbiodegradable polymers and biodegradable commercial polymers such as poly (vinyl alcohol) (PVA) can facilitate a reduction in the volume of plastic waste when they undergo partial degradation. Further, the remaining fragments stand a greater chance of undergoing biodegradation in a much shorter span of time. In this investigation, LLDPE was blended with different proportions of PVA (5–30%) in a torque rheometer. Mechanical, thermal, and biodegradation studies were carried out on the blends. The biodegradability of LLDPE/PVA blends has been studied in two environments: (1) in a culture medium containing Vibrio sp. and (2) soil environment, both over a period of 15 weeks. Blends exposed to culture medium degraded more than that exposed to soil environment. Changes in various properties of LLDPE/PVA blends before and after degradation were monitored using Fourier transform infrared spectroscopy, a differential scanning calorimeter (DSC) for crystallinity, and scanning electron microscope (SEM) for surface morphology among other things. Percentage crystallinity decreased as the PVA content increased and biodegradation resulted in an increase of crystallinity in LLDPE/PVA blends. The results prove that partial biodegradation of the blends has occurred holding promise for an eventual biodegradable product. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Properties of soy protein isolate/poly(vinyl alcohol) blend “green” films: Compatibility,mechanical properties,and thermal stability

Blend films from nature soy protein isolates (SPI) and synthetical poly(vinyl alcohol) (PVA) compatibilized by glycerol were successfully fabricated by a solution‐casting method in this study. Properties of compatibility, mechanical properties, and thermal stability of SPI/PVA films were investigated based on the effect of the PVA concentration. XRD tests confirm that the SPI/PVA films were partially crystalline materials with peaks of 2θ = 20°. And, the addition of glycerol will insert the crystalline structure and destroy the blend microstructure of SPI/PVA. Differential scanning calorimetry (DSC) tests show that SPI/PVA blend polymers have a single glass transition temperature (T_g) between 80 and 115.0°C, which indicate that SPI and PVA have good compatibility. The tension tests show that SPI/PVA films exhibit both higher tensile strength (σ_b) and percentage elongation at break point (P.E.B.). Thermogravimetric analysis (TGA) and water solubility tests show that SPI/PVA blend polymer has more stable stability than pure SPI. All the results reflect that SPI/PVA/glycerol blend film provides a convenient and promising way to prepare soy protein plastics for practical application. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and properties of novel polyvinyl alcohol–lactic acid gels

This article describes a process for esterifying polyvinyl alcohol (PVA) with L‐lactide (LLA) and D,L‐lactic acid (LA), using ethyl acetate and N,N′‐dimethyl formamide at temperatures varying from 120 to 150°C. The grafting process was carried out under nitrogen to avoid possible oxidation or other degradation of the process ingredients and product. Lower T_g values were obtained for the PVA/LLA graft copolymers of higher LLA content suggesting some compatibility in the amorphous phase. Higher T_g values were observed for PVA/LA graft copolymers that yielded tough polymer films. The structure of the copolymers was studied by solid‐state ¹³C‐NMR, infrared spectroscopy, and differential scanning calorimetry (DSC). The PVA/LA films exhibited melt processability and good mechanical properties such as yield strength, tensile energy at break, modulus, and elongation at break. The polymer films produced through compression molding at 100°C showed good swelling properties. The transport coefficient (n) values determined from the plot of log(M_t/M_∞) vs. log t indicate Fickian behavior, and they are consistent with the reported literature values for other PVA systems. The nature of water in gels [bound water (W_b), freezing (W_f), and freezing bound (W_fb), and water content (W_t)] was evaluated from DSC data. The results demonstrate that PVA/LA hydrogels with good combination of thermal, physicomechanical, and swelling properties can be prepared via the lactic acid esterification of PVA polymer process described. Besides being melt processable, the PVA/LA gels exhibit a melting point, which indicates possibly use of higher temperatures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009