Preparation and Properties of Biodegradable Polymer Film Based on Polyvinyl Alcohol and Tropical Fruit Waste Flour

In this study, two different types of tropical fruit waste flour, rambutan waste flour (RWF) and banana waste flour (BWF), were blended with polyvinyl alcohol (PVOH) by solution casting method. The structure of the blend film was characterised by Fourier Transform Infrared Spectroscopy. The tensile strength and elongation at break of tropical fruit waste flour-filled polyvinyl alcohol were lower, but the tensile modulus was higher, than that of PVOH film. At a similar blend ratio, the tensile properties of the PVOH/RWF film were higher than the PVOH/BWF film, but the PVOH/BWF film showed higher water uptake than PVOH/RWF film.     

Effects of jackfruit waste flour on the properties of poly(vinyl alcohol) film

A series of biodegradable polymer films based on poly(vinyl alcohol) (PVOH) and jackfruit waste flour (JWF) was prepared in the presence of water and glycerol and cast by a solution casting method. The JWF was introduced as a promoter of biodegradability. The blended films were evaluated for their tensile properties, water absorption, water vapor transmission rate (WVTR), and degradation behavior under different environmental conditions such as natural weathering and natural soil. The tensile strength (1.7–6.4 MPa) and elongation at break (13–108%) of the PVOH/JWF films were lower than those of unfilled PVOH film (26MPa and 238%). However, the Young's modulus values (157–196 MPa) of the PVOH/JWF films were higher than that of unfilled PVOH film (137 MPa). The PVOH/JWF blended films showed higher water absorption and WVTR, which increased with increasing JWF content. Biodegradability tests revealed that the presence of JWF stimulated the degradation rate and caused the weight loss and reduction in tensile properties of the PVOH/JWF blended films. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Crosslinked glutinous rice starch filled polyvinyl alcohol films

The influence of glutinous rice starch (GRS) content and sodium hexametaphosphate (SHMP) in polyvinyl alcohol (PVOH) films were studied. The increase of GRS content (0–40 wt%) reduced the tensile strength (from 14.3 to 4.3 MPa) and elongation at break (from 183 to 52.5) of PVOH/GRS films. Nevertheless, the modulus of elasticity of PVOH/GRS films increased with GRS content, from 20.3 to 132.83 MPa. SHMP was used as a crosslinking agent, which improved more than 30% of tensile strength and modulus of elasticity of PVOH/GRS films. However, the elongation at break reduced after crosslinking process of the films. The crosslinked film showed better interaction between GRS and PVOH, as demonstrated by scanning electron microscopy. Conversely, the crosslinked films exhibited a lower swelling degree, but a higher gel content compared to uncrosslinked films. J. VINYL ADDIT. TECHNOL., 25:359–365, 2019. © 2019 Society of Plastics Engineers     

Preparation and characterization of ultrahigh molecular weight polyethylene and polyisoprene solvent-cast blend films

This study covers the preparation of noncrosslinked and crosslinked solvent-cast blend films of ultrahigh molecular weight polyethylene (UHMWPE) and polyisoprene rubber (PIR) and their mechanical, thermal, IR spectroscopic, and morphological characterizations. Solvent-cast films of polymer blends with 0, 10, 20, 35, 50, and 65% PIR composition were prepared by vigorous stirring from a hot decalin solution. The films were crosslinked chemically by using acetophenone as a crosslinking agent under UV radiation. The mechanical properties, measured as ultimate properties and tensile modulus, were found to decrease with PIR content but crosslinking was found to enhance the ultimate strength and tensile modulus. DSC results revealed that melting point of UHMWPE remains almost constant in blends. However, upon crosslinking, the melting point of UHMWPE is depressed almost 5°C. We observed a similar trend in the enthalpy change of the melting of UHMWPE and the variation of percent crystallinity in UHMWPE. Scanning electron microscopy (SEM) studies on the fractured surfaces of the blends showed that the fibrillar texture is present in both crosslinked and noncrosslinked blends. The crosslinking appeared to be through oxygen linkages, which are preferentially conjugated to double bonds, in addition to the possible carbon–carbon crosslinks. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1619–1630, 1998     

Tensile properties,degradation behavior,and water absorption of sago starch plastic films

Sago starch plastic films were prepared by a blending and casting method using various amounts of additives. The additives were glycerol (GLY), polyethylene glycol (PEG), and glutaraldehyde (GLU). Results indicated that the films had an optimum tensile strength of about 2.6 MPa and an optimum elongation at break of 74%. Meanwhile, a GLU content of five parts by weight gave the best tensile properties. Elongation at break of the films increased while tensile strength decreased upon increasing the level of plasticizer (GLY and PEG). The addition of plasticizer also increased the water absorption and soil burial degradation rate. However, the addition of GLU gave opposite results. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Synthesis of Chemically Modified Polyvinyl Alcohol Membranes for Dehydration of Dioxane by Pervaporation

Abstract

Polyvinyl alcohol (PVOH) has been chemically modified by polymerizing hydroxyethylmethacrylate (HEMA) in aqueous solution of PVOH and finally crosslinking PVOH with glutaraldehyde to produce a semi-interpenetrating network (SIPN) membrane. Accordingly, three such SIPNs i.e., SIPNI, SIPNII, and SIPNIII were synthesized with different weight ratio of PVOH: HEMA i.e., 1:0.25 (SIPNI), 1:0.50 (SIPNII) and 1:0.75 (SIPNIII). These SIPN membranes were used for pervaporative dehydration of dioxane. PVOH without any chemical modification but crosslinked with the same amount of glutaraldehyde has also been used for this study for comparison. All the SIPN membranes were also characterized with various conventional methods like mechanical properties, DSC and TGA. Water permeability and water selectivity of the IPN membranes were found to be much higher than those of the crosslinked PVOH membrane which was not chemically modified. The permeability of the membranes were also found to increase with increase in the HEMA content in PVOH matrix.     

Eco-friendly coupling agent-treated kenaf/linear low-density polyethylene/poly (vinyl alcohol) composites

Untreated kenaf (KNF) and eco-friendly coupling agent (EFCA)-treated kenaf were used as filler to prepare natural fiber-reinforced polymer composites (NFPCs) using linear low-density polyethylene (LLDPE) and poly(vinyl alcohol) (PVOH) as polymer matrices. The composites containing various loadings of untreated and EFCA-treated KNF (0, 10, 20, and 40 phr) were melt-blended in an internal mixer. The effect of treatment on the behavior of processing torque, mechanical properties, morphology, functional groups, water absorption, and thermal stability of KNF/LLDPE/PVOH composites were investigated. The results revealed that EFCA-treated KNF composites exhibited higher equilibrium torque, indicating that the viscosity of molten composites increased in the presence of EFCA. The tensile strength and tensile modulus of KNF/LLDPE/PVOH composites were improved with the addition of EFCA-treated KNF attributed to the enhancement of the interfacial adhesion between KNF and LLDPE/PVOH matrices, as confirmed by field-emission scanning electron microscopy. Fourier transform infrared spectroscopy indicated the presence of ester bond in EFCA-treated KNF composites. Furthermore, EFCA-treated KNF composites possessed a lower water absorption and greater thermal stability as compared to untreated KNF composites. Therefore, EFCA could be suggested as an effective coupling agent to enhance the performance of KNF/LLDPE/PVOH composites.     

Crosslinked poly(vinyl alcohol) and starch composite films. II. Physicomechanical,thermal properties and swelling studies

Poly(vinyl alcohol) (PVA) was blended with 10, 20, 30, 40, and 50 wt % of starch with and without crosslinking by solution casting process. The solution‐casted films were dried and tested for physicomechanical properties like tensile strength, tensile elongation, tensile modulus, tear and burst strengths, density, and thermal analysis by differential scanning calorimetry (DSC). These PVA/starch films were further characterized for moisture content; solubility resistance in water, 5% acetic acid, 50% ethanol, and sunflower oil; and swelling characteristics in 50% ethanol and sunflower oil. The crosslinked PVA/starch composite films show significant improvement in tensile strength, tensile modulus, tear and burst strengths, and solubility resistance over the uncrosslinked films. Between the crosslinked and uncrosslinked films, the uncrosslinked films have higher tensile elongation, moisture content, moisture absorption, and swelling over the crosslinked films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 909–916, 2007     

Moisture‐induced effects on the tensile mechanical properties and glass‐transition temperature of poly(vinyl alcohol) films

In this study, the effect of sorbed water on the tensile mechanical properties of noncrosslinked, thermally treated poly(vinyl alcohol) (PVA) films was studied. The Young's modulus, elongation at break, and tensile strength of the PVA films equilibrated at different relative humidities (0–86%) are reported, together with the depression of the glass transition of the polymer at each equilibrating humidity, as determined by temperature‐modulated differential scanning calorimetry. The results indicate that drastic changes in the tensile properties were correlated with the transition of the hydrated polymer from the glassy to the rubbery state. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microstructure and properties of new polyimide/polysiloxane composite films

A series of novel polyimide/polydiphenylsiloxane) (PI/PDDS) composite films with different contents of DDS were prepared using sol–gel method. The noncrosslinked PI–DDS and crosslinked PIS–DDS were synthesized through cohydrolysis and condensation between DDS and polyamic acid (PAA) or aminopropyltriethoxysilane(APTES)‐terminated polyamic acid (PAAS). All the composite films have high thermal stability near pure PI. Field emission scanning electron microscopy (FE‐SEM) study shows that the polysiloxane from hydrolyzed DDS well dispersed in polyimide matrix, without macroscopic separation for the composite films with low content of DDS, while large domain of polysiloxane was formed in films with high DDS content. The microstructure of composite films is in accordance with the transparency of corresponding films. X‐ray study shows the PDDS is amorphous in PI matrix. The introduction of DDS into PI can improve the elongation at break and at the same time, the composite films still remained with higher modulus and tensile strength. The density and water absorption of the composite films decreased with the increasing DDS content. The composite films with DDS content below 10 wt % exhibit good solvent resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 124–132, 2006     

Degradation of linear low-density polyethylene/poly(vinyl alcohol)/kenaf composites

The interest of this study was to examine various kenaf (KNF) loadings and burial time, and their effects on degradability behavior of linear low-density polyethylene/poly(vinyl alcohol)/kenaf (LLDPE/PVOH/KNF) composites in soil. The LLDPE/PVOH/KNF composites with various KNF loadings were melt-mixed in a Thermo Haake internal mixer. The composites were buried in soil and their extent of degradability was assessed by tensile properties, morphological study, and weight loss and crystallinity measurements of the degraded composites. Fourier transform infrared spectroscopy was utilized to monitor the changes in chemical structure of the composites before and after degradation in soil. The results showed that with increase in KNF loading, the tensile modulus increased; meanwhile, the tensile strength and elongation-at-break of the degraded composites were dropped. Tensile properties of the degraded composites were decreased with prolonging soil burial time. The formation of cracks and pores was observed in field emission scanning electron microscope micrographs. By measuring the weight loss in LLDPE/PVOH/KNF composite samples before and after the soil burial testing and differential scanning calorimetry measurements, it was found that the weight loss and crystallinity of the composites increased with soil burial time. The degradation of the composites was confirmed by the formation of a strong absorption band assigned to carbonyl groups.     

Synthesis and properties of crosslinked waterborne polyurethane

Waterborne polyurethane prepolymer was prepared by the reaction of isophorone isocyanate(IPDI), polyether polyol(PTMG), dimethylol propionic acid(DMPA) and trimethylol propane(TMP), which was modified by silicane coupling agent(APTES) to form highly crosslinked polyurethane emulsion. The films of the waterborne polyurethane were prepared. The structure of the polyurethane was characterized by Fourier transform infared spectrometer (FTIR), X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The mechanical properties and water absorption of the films were measured. FT-IR indicates that APTES reacted with -NCO of polyurethane. XRD and DSC shows that crystallinity of polyurethane decreased with the increase of w(APTES). Tensile strength increases as the NCO/OH ratio increases. Tensile strength of films increases with increase of w(DMPA) and elongation at break decreases. The water absorption decreases with the increase of w(TMP) when w(TMP) is lower than 1.8%. As the mass fraction of APTES increases from 0% to 10%, the tensile strength of PU films increased from 18 MPa to 28 MPa, water absorption and ethanol absorption decreased.     

Effect of Attapulgite Clay on Biodegradability and Tensile Properties of Polyvinyl Alcohol/Corn Starch Blend Film

Polyvinyl alcohol (PVOH) with corn starch (CS) at 70/30 weight percent ratio were prepared by a solution casting method with the addition of attapulgite at a range of 0.0–1.0 grams. The aim of this study is to investigate the effect of attapulgite on biodegradability and tensile properties of PVOH/CS matrix. All the results were compared with the control sample (PVOH/CS). The presence of attapulgite had hindered the degradation process in enzymatic, soil, and compost burial. The water sorption content increased with increasing immersion time. The highest tensile strength and elongation at break were shown by the PVOH/CS with 0.2 g of attapulgite content.     

Separation of toluene–methanol mixtures by pervaporation using crosslink IPN membranes

Polyvinyl alcohol (PVOH) has been chemically modified by crosslink copolymerization of acrylic acid (AA) and hydroxyethylmethacrylate (HEMA) in aqueous solution of PVOH and finally crosslinking PVOH to produce a full interpenetrating network (IPN) membrane termed as PVAH. Accordingly, three such full crosslink IPNs membranes, i.e. PVAHI, PVAHII and PVAHIII containing varied weight ratio of PVOH and copolymer have been synthesized and used for pervaporative separation of methanol from its mixtures with toluene. For comparison, a conventional PVOH membrane crosslinked with glutaraldehyde has also been used for the same pervaporation study. The flux and selectivity of these IPN membranes were found to be much higher than the conventional glutaraldehyde crosslinked PVOH membrane. Among the three membranes, PVAHII with 50 wt% polyAH incorporation showed optimum performance in terms of flux and methanol selectivity.     

Influence of nanovermiculites with a high aspect ratio and stretch orientation on the microstructure of polypropylene films

In this article, we present a process for preparing organovermiculites, which consist of expanded vermiculite (EVMT)–poly(vinyl alcohol) (PVOH) created by the mechanical ball‐milling of EVMT in a PVOH–water solution. We then discusses the influence of EVMT–PVOH on the barrier performance, crystallization behavior, thermal stability, and mechanical properties of modified blown polypropylene (PP) films. EVMT was intercalated and exfoliated by PVOH macromolecules to obtain a kind of hybrid EVMT–PVOH. PVOH served as both an intercalating agent into EVMT and a compatibilizer between EVMT and PP. Compared with the original (unmodified) PP, when the EVMT loading ranged from 0.1 to 2.0%, although the crystallinity decreased for most PP films, the thermal stability and mechanical properties all improved. Moreover, EVMT platelike particles with a high aspect ratio (ca. 550) dispersed in the PP matrix also improved the barrier properties of the modified PP films, which was in accordance with the Nielsen model. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42846.     

Extruded foams prepared from high amylose starch with sodium stearate to form amylose inclusion complexes*

Extruded starch foams were prepared from high amylose corn starch with and without sodium stearate and poly(vinyl alcohol) (PVOH) to determine how the formation of amylose–sodium stearate inclusion complexes and PVOH addition would affect foam properties. X‐ray diffraction and Differential Scanning Calorimetry (DSC) showed that amylose–sodium stearate inclusion complexes were formed by low temperature extrusion and did not dissociate during foam formation by a second extrusion at higher temperatures. In the absence of PVOH, water absorption, and foam shrinkage at 95% RH were decreased because of the hydrophobicity of the complex. PVOH addition increased both the expansion ratio and the shrinkage of the foam, although shrinkage at 95% RH was still less than that observed with uncomplexed amylose. The structural integrity and some tensile properties of stearate‐containing foams were improved by PVOH addition. These results provide the manufacturer of biodegradable starch foams with an inexpensive method for tailoring foam properties for specific end‐use applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43251.     

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     

Tensile,Swelling, and Oxidative Degradation Properties of Crosslinked Polyvinyl Alcohol/Chitosan/Halloysite Nanotube Composites

Glutaraldehyde (GA) crosslinked polyvinyl alcohol (PVA)/chitosan (CS)/halloysite nanotube (HNT) composite films were prepared using a wet casting method. The tensile, morphology, thermal degradation, swelling, moisture, and oxidative degradation properties of crosslinked composite films were carried out. The presences of crosslinking in the composite films were confirmed by FTIR result. The tensile strength of the crosslinked composite films increased up to 0.5 wt% of HNTs loading. Increasing HNTs reduced the thermal degradation, swelling, and moisture properties of crosslinked composite films reduced with the increase of HNTs content. Results also indicated that the crosslinked composite films were degraded using Fenton reagent.     

Effect of crosslinking on the surface free energy and surface reorganization of waterborne fluorinated polyurethane

To endow waterborne fluorinated polyurethanes (WFPUs), films with stable lower surface free energy and lower surface reorganization after the films contacted with water, a series of crosslinked WFPUs (CWFPUs) emulsions were prepared by adjusting the content of aziridine (AZ). The effect of crosslinking on the surface free energy, glass-transition temperature (T _g), water absorption, and surface composition of dry/hydrated WFPUs and CWFPUs films were studied by CAs test, dynamic mechanical analysis, water absorption measurements, and X-ray photoelectron spectroscopy. When the fluorine content was 0.5%, the surface free energy of the CWFPUs films modified by 0.4% AZ content (CWFPU-6-0.5-CK0.4) reached to the lowest value of 15.76 mN m⁻¹ which almost equaled to the surface free energy (15.45 mN m⁻¹) of the dry uncrosslinked films (WFPU-6-0.5). With the increasing of AZ content, the T _{g, hard} of hard segments of the CWFPUs films increased and the water absorption of the CWFPUs films decreased, which suggested the formation of the crosslinked network structures. The studies of the surface elements and groups composition of dry/hydrated WFPUs and CWFPUs both confirmed that the surface reorganization and the migration of fluorinated side chains were restricted by the crosslinked network structures. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47167.     

Improvement of mechanical properties of graphene oxide/poly(allylamine) composites by chemical crosslinking

Graphite oxide was prepared by oxidation of graphite using the Hummers method, and its ultrasonication in water yielded dispersed graphene oxide (GO) sheets. These sheets were then crosslinked with a water soluble polymer, namely poly (allylamine) hydrochloride (PAH), by carbodiimide coupling. Free standing composite films were obtained by filtration. These crosslinked composites showed better mechanical properties than unmodified GO films and those of composites that were made by simple mixing of GO and PAH. The filtration process was optimized to produce strong GO films which were subsequently crosslinked with PAH in-situ to produce very strong composites with tensile strengths up to146 MPa.