Mechanical properties and water vapor permeability of thin film from corn hull arabinoxylan

Isolated corn hull arabinoxylan was dissolved in water and provided a clear solution. Plasticizer (glycerol, propylene glycol, or sorbitol) was added to the arabinoxylan solution at 0–20 wt % (film dry weight), which was cast into stable films. Film thickness ranged from 22 to 32 μm. Mechanical properties, moisture content, and water vapor permeability (WVP) were studied for the arabinoxylan‐based films as a function of plasticizer concentration. Measured data for the corn hull arabinoxylan–based films were 13–18 wt % moisture content, 10–61 MPa tensile strength, 365–1320 MPa modulus, 6–12% elongation, and 0.23–0.43 × 10^?10 g m^?1 Pa^?1 s^?1 water vapor permeability. Plasticized arabinoxylan films produced in this study had lower WVPs than those of unplasticized films, which is likely attributable to the phenomenon known as antiplasticization. Scanning electron micrographs showed a homogeneous structure on film surfaces. Films containing sorbitol had the best moisture barrier properties. When grapes were coated with arabinoxylan and arabinoxylan/sorbitol films, weight loss rates of the fruit decreased by 18 and 41%, respectively, after 7 days. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2896–2902, 2004     

Mechanical and water binding properties of carboxymethyl cellulose/multiwalled carbon nanotube nanocomposites

Carboxymethyl cellulose (CMC) composite films were prepared from CMC solutions (2% w/v) containing multiwalled carbon nanotubes (MWCNT) as nanofiller and glycerol (25% w/w CMC) as plasticizer. Tensile strength, elongation at break (EAB), young's modulus, water solubility, water swelling, water uptake, and water vapor permeability (WVP) for CMC films were 27.5 ± 2.5 MPa, 11.2 ± 0.8%, 198 ± 18 MPa, 57 ± 1.5%, 738 ± 25%, 124 ± 4%, and 0.55 ± 0.036 g.mm/m².kPa.h, respectively. By increasing the relative humidity from 11.4 to 85.5%, the moisture absorption (MA) of CMC films was increased from 4 to 38%. Incorporation of MWCNT into the matrix caused a significant increase in the tensile strength, decrease in EAB, increase in young's modulus, decrease in water solubility, decrease in water swelling, decrease in water uptake, and decrease in MA. CMC/MWCNT films containing 1% MWCNT showed the lowest WVP. Scanning electron microscopy showed a good dispersion of MWCNT in the CMC matrix. CMC/MWCNT films containing >1% MWCNT showed significant antibacterial activities against both Gram‐positive and Gram‐negative bacteria in a dose‐dependent manner. Thus, good mechanical properties and water resistance along with strong antibacterial activities make CMC films grafted with MWCNT as a suitable packaging material. POLYM. COMPOS., 36:145–152, 2015. © 2014 Society of Plastics Engineers     

Edible starch sodium octenyl succinate film formation and its physical properties

Edible starch sodium octenyl succinate (SSOS) films, with or without glycerol as plasticizer, were prepared by solution‐casting method. The effect of SSOS concentration, degree of substitution (DS) of octenyl group, as well as glycerol content, on the properties of SSOS films was studied including tensile strength, water vapor permeability (WVP), and oil permeability (OP). The results indicated that the tensile strength of SSOS film was up to 39.4 ± 1.9 MPa when the concentration of SSOS was 0.05 g/mL and DS was 0.05. The increase of glycerol content resulted in a decrease of film tensile strength. WVP of SSOS films was relatively low. Meanwhile, study in OP showed that SSOS films were oilproof. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Structure and mechanical properties of soy protein materials plasticized by Thiodiglycol

Thiodiglycol (TDG) is a relatively nontoxic compound from organic wastes. By using TDG as a plasticizer with weights from 2.5 to 40%, we prepared soy protein isolate (SPI) films by a compression‐molding technique at 140°C and 15 MPa. The TDG‐plasticized films (SPI–TDG films) were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, dynamic mechanical thermal analysis, thermogravimetric analysis, optical transmittance, and water uptake experiments. The SPI–TDG film plasticized with 25% TDG exhibited good mechanical properties, such as a tensile strength and modulus of 20.3 and 582 MPa, respectively, whereas the SPI–glycerol film with 25% glycerol had a tensile strength and modulus of 16.2 and 436 MPa, respectively. The results from the thermogravimetric analysis and water uptake experiments indicated that the thermal stability and water resistance of the TDG‐plasticized SPI materials were higher than that of the glycerol‐plasticized one. The improvements in the mechanical properties, water resistance, and thermal stability of the SPI–TDG films could be attributed to the strong intermolecular hydrogen bonding between soy protein and TDG and the presence of fewer hydroxyl groups in TDG, as compared structurally with glycerol. This study provided a new plasticizer for the preparation of soy protein materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Water vapor absorption and permeability of films based on chitosan and sodium caseinate

The objective of this work was to characterize the moisture sorption and water vapor permeation behavior of edible films made from sodium caseinate and chitosan for future applications as protective layers on foods. Glycerol was used as a plasticizer, and the films were obtained by a casting/solvent‐evaporation method. The moisture sorption kinetics and water vapor permeability (WVP) were investigated. The effect of the addition of glycerol on the WVP characteristics of the films was determined at 25°C with a relative humidity (RH) gradient of 0–64.5% (internal to external). Experimental data were fitted with an exponential function with two fitting parameters. WVP increased with increasing glycerol content in both films, chitosan samples being much more permeable than caseinate ones at any glycerol content. WVPs of sodium caseinate, chitosan, and chitosan/caseinate films with 28 wt % glycerol were also determined for two RH gradients, 0 to 64.5% and 100 to 64.5%, higher WVPs being measured at higher RHs. The moisture sorption kinetics of caseinate films prepared with various glycerol contents were determined by the placement of the films in environments conditioned at 20°C and 75% RH. Peleg's equation and Fick's second law were used to predict the moisture sorption behavior over the entire time period. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Potential of Pinhão husk (Araucaria angustifolia) as a structural reinforcement agent in the properties of edible films of Pinhão flour and gelatin

In this study, the use of Pinhão husk as a source of reinforcement material for development of edible films, where the Pinhão seed flour and bovine gelatin were used as matrices for the films. Mechanical properties, water vapor permeability, solubility and opacity, microstructure, and thermal degradation characterized the films produced. The films presented homogeneous and cohesive structures. Pinhão husk content positively affected film properties by increasing tensile strength (TS) and decreasing water vapor permeability (WVP), with Pinhão flour film formulations (5.0% Pinhão flour, 1.2% glycerol, and 0.4% Pinhão husk) and gelatin (5.0% gelatin, 2.0% glycerol, and 0.4% Pinhão husk) those that presented the best results (5.06 MPa for TS and 0.14 g.mm/kPa.h.m² for WVP) and (3.88 MPa for TS and 0.28 g.mm/kPa.h.m² for WVP), respectively The thermal degradation study revealed that the films are stable at temperatures below 150°C, losing only free water and volatile compounds of low molecular weight. Pinhão husk can reinforce films, making them suitable as biodegradable and edible packaging materials for eco-friendly food products. This contributes to the circular economy, preserves biodiversity, and reduces plastic waste, offering promising sustainable packaging solutions.     

Heterogeneous method of chitosan film preparation: Effect of multifunctional acid on film properties

The heterogeneous crosslinking method was applied to chitosan films with citric acid to observe and understand the effect of a multifunctional acid at a low concentration on film properties. Neat and neutralized chitosan films and films containing 15% (w/w) citric acid (denoted as CA films) were characterized by mechanical, water vapor permeability (WVP), and thermogravimetric analysis tests. The CA films displayed a higher tensile strength by 10%, lower WVP by 30%, and higher thermal stability, compared to neutralized films. The crystalline structure converted back from tendon to Type II after the addition of citric acid, as determined by X-ray diffraction. Neat films displayed a lower water contact angle (72°) compared to neutralized and CA films (78°–79°). The heterogeneous method was also applied to incorporate a plasticizer into a neutralized film to potentially observe the glass transition using dynamic mechanical analysis. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48648.     

Bio‐based polymeric resin from agricultural waste,neem (Azadirachta indica) seed cake,for green composites

Protein‐based polymeric resin has been developed from nonconventional and nonedible “neem seed cake (NSC)” that has very limited low‐value applications. Neem protein (NP), after extraction from defatted NSC, was used to prepare resin with two common plasticizers (glycerol and sorbitol). Properties of the NP resin sheets were evaluated as a function of plasticizer content. Increase of plasticizer content in NP sheets from 15 to 30% (w/w) enhanced fracture strain with a reduction in tensile strength, modulus, and thermal properties. Sorbitol‐plasticized NP sheets showed better mechanical and thermal properties in comparison to glycerol‐plasticized sheets. Effect of cross‐linking with glyoxal on the mechanical and thermal properties of sorbitol‐plasticized NP sheets was also investigated. Properties improved significantly at 10% (w/w) glyoxal content. Overall, with the enhanced properties of NP sheets, NP can be a viable alternative for edible protein‐based resin for making green composites. NP resin can also be used to replace some synthetic resins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 10.1002/app.41291.     

Water vapor barrier and mechanical properties of konjac glucomannan–chitosan–soy protein isolate edible films

The effects of polymer composition, glycerol concentration and pH of film-forming solution on water vapor permeability (WVP), tensile strength (TS) and percentage elongation at break (%E) of composite edible film based on konjac glucomannan (KGM), chitosan and soy protein isolate (SPI) were investigated. Of the plasticizers tested, glycerol was found to be a suitable plasticizer regarding mechanical properties and WVP. The WVPs of the films were determined to be (3.29–9.63) × 10^?11 g m^?1 s^?1 Pa^?1, TS between 16.77 and 51.07 MPa, and %E between 1.29% and 10.73%, depending on film composition. Incorporation of SPI to the polymer matrix decreased both WVP and mechanical properties. Increase in both glycerol concentration and the pH of film-forming solution decreased WVP and TS but increased %E. The results suggest that film composition and the pH of film-forming solution are the major factors influencing the film properties.     

Mechanical and barrier properties of nanocrystalline cellulose reinforced poly(caprolactone) composites: Effect of gamma radiation

Nanocrystalline cellulose (NCC) reinforced poly(caprolactone) (PCL) composites were prepared by compression molding. The NCC content varied from 2 to 10% by weight. NCC played a significant role in improving the mechanical properties of PCL. The addition of 5 wt % NCC caused a 62% improvement of the tensile strength (TS) value of PCL films. Similarly, tensile modulus (TM) values were also improved by NCC reinforcement but elongation at break (Eb) values decreased montonically with NCC content. The water vapor permeability (WVP) of PCL was 1.51 g·mm/m²·day·kPa, whereas PCL films containing 5 wt % NCC showed a WVP of 1.22 g·mm/m²·day·kPa. The oxygen transmission rate (OTR) and carbon dioxide transmission rate (CO₂TR) of PCL decreased by 19 and 17%, respectively, with 5 wt % NCC incorporation. It was found that the mechanical and barrier properties of both PCL and PCL‐NCC composites further improved with 10 kGy gamma irradiation treatment. The combination of NCC and radiation significantly increased the TS, TM, and Eb (by 156, 123, and 80%, respectively, compared to untreated PCL). The WVP, OTR, and CO₂TR decreased by 25–35% with respect to untreated PCL. The surface and interface morphologies of the PCL‐NCC composites were studied by scanning electron microscopy and suggested homogeneous distribution of NCC within the PCL matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Influence of preparation conditions on the physical properties of zein films

Zein is a hydrophobic protein produced from maize. Biodegradable zein films without additional reagents were prepared using various controlled drying conditions. The zein films were transparent. Mechanical properties (tensile strength and puncture strength), gas permeability, and water vapor permeability (WVP) of the zein films were measured. The tensile strengths of the zein films were between 7 and 30 MPa and the puncture strengths between 37 and 191 MPa. The zein films had higher oxygen permeability than carbon dioxide permeability. The lowest WVP of the zein film was 0.012×10⁻⁹ g·m/m²·s·Pa. We found differences in the WVP between the sides of the zein films; i.e., the air side of the zein film had a higher WVP than the basal side of the zein film when the films were exposed to high humidity during testing. This indicates a relationship between the WVP of the zein film and the contact angle of the zein film. The mechanical properties of the zein film depended on the drying conditions during preparation. Zein films with various useful physical mechanical properties were produced.     

Mechanical properties and release studies of chitosan films impregnated with silver sulfadiazine

The purpose of these studies was to evaluate chitosan films impregnated with silver sulfadiazine as potential wound dressings, based on their mechanical properties and the controlled‐release phenomenon. The mechanical properties of such films were investigated under varying plasticizers (glycerol or sorbitol) concentrations, as well as in the presence of a crosslinking agent (formaldehyde). The drug release was also determined under such varying conditions, as well as using different thicknesses of film and drug concentrations. The results showed that the additives decreased the tensile strength of the chitosan films (except for sorbitol at 20% w/w), while at the same time remarkably enhancing the percentage elongation of the films. This elongation was especially pronounced in the case of glycerol. The type of plasticizer also influenced the release of silver sulfadiazine. Glycerol had a greater effect than sorbitol on the release rate, regardless of the amount used, probably due to leakage of this additive from the film, which leaves pores that enhance the water uptake of the film. As might be expected, increased concentrations of entrapped silver sulfadiazine yielded increasingly higher release rates. Decrease in thickness of the film also enhanced the release rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3462–3470, 2006     

Mechanical,barrier, and interfacial properties of biodegradable composite films made of methylcellulose and poly(caprolactone)

Methylcellulose (MC) films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol, and 0.025% Tween^®80. Poly(caprolactone) (PCL) films were prepared by compression molding from its granules. Biodegradable composite films were fabricated using MC film as reinforcing agent and PCL as the matrix material by compression molding. One layer of MC film was reinforced with two layers of PCL films. The MC content in the composites was varied from 10 to 50% by weight. Mechanical, barrier, and degradation properties of PCL, MC, and composite films were evaluated. The values of puncture strength (PS), puncture deformation (PD), viscoelasticity (Y) coefficient, and water vapor permeability (WVP) of the composites (50% MC content) were found to be 124.3 N/mm, 3.2 mm, 31%, and 2.6 g·mm/m²·day·kPa, respectively. Oxygen transmission rate (OTR) of PCL, MC, and composites (50% MC) were found to be 175, 25, 22 cc/m²/d, respectively, which indicated that composite films showed significantly lower OTR than PCL films. Degradation tests of the composite films (50% MC) were performed for 6 weeks in aqueous medium (at 25°C), and it was found that composites lost its mass slowly with time. After 6 weeks, mass and PS of the composites were decreased to 13.4 and 12%, respectively. Composite interface was studied by scanning electron microscopy (SEM). The MC film had good adhesion with PCL matrix during compression molding and suggested strong interface of the composite system. SEM image after 6 weeks of degradation showed some openings in the interface and revealed slow degradation of the MC films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and properties of thermoplastic pea starch using N,N‐bis(2‐hydroxyethyl)formamide as the plasticizer

N,N‐bis(2‐hydroxyethyl)formamide (BHF) was synthesized efficiently and used as a new plasticizer for pea starch to prepare thermoplastic starch (TPS). The hydrogen bond interaction between BHF and pea starch was proven by Fourier‐transform infrared (FT‐IR) spectroscopy. As detected by scanning electron microscope (SEM), pea starch granules were completely disrupted, and the homogeneous materials were obtained. The crystallinity of pea starch and BHF‐plasticized thermoplastic pea starch (BTPS) was characterized by X‐ray diffraction (XRD). Rheological properties of TPS were analyzed. The water resistance of BTPS was better than that of glycerol‐plasticized thermoplastic pea starch (GTPS). At RH 33%, the tensile strength of BTPS was higher than that of GTPS for TPS containing 30% plasticizer. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Films of chitosan and N‐carboxymethylchitosan. Part II: effect of plasticizers on their physiochemical properties

Chitosan (Ch) and N‐carboxymethylchitosan (N‐CMCh) films were prepared by the casting method at concentrations of 1% and 2% of polymer, with or without plasticizer: polyethylene glycol (PEG‐400) and glycerol (G), at 15% (w/w). The influence of composition on mechanical properties, water vapour transmission rate (WVTR), water saturation, and aqueous dissolution of the films was analysed. The thermal stability of the mixture (polymer:plasticizer, 1:1) was evaluated by thermogravimetric analysis (TGA). In general, all the properties were affected by the plasticizers. The plasticized films showed lower strength and a higher percentage of elongation (%E), in the following order: G > PEG‐400 > unplasticized film. The total WVTR increased with Ch concentration, with a different WVTR profile for Ch and N‐CMCh. While the PEG‐400 addition did not significantly modify the WVTR profile of films, the glycerol enhanced the transport of water vapour through both polymers. The plasticizer addition increased the time of water film saturation, in the following order: G > PEG‐400 > unplasticized film; this was more pronounced in the N‐CMCh films, probably due to the formation of hydrogen bonds. The solubility of the films was also affected by their composition. Copyright © 2006 Society of Chemical Industry     

Physico-chemical properties of lignin–alginate based films in the presence of different plasticizers

A lignin–alginate blended film was prepared in the presence of three different plasticizers, viz. glycerol, epichlorohydrin (EPC) and poly(ethylene glycol) (PEG) and the effect of each plasticizer was studied on physico-chemical properties of the blended film. Lignin extracted from Acacia wood by alkali extraction process was blended with alginate to obtain lignin–alginate film in the presence of different plasticizers. A film plasticized with glycerol displayed higher solubility and swelling percentage as compared to EPC and PEG plasticized films. The highest tensile strength was observed for film plasticized with PEG, and none of the plasticizers made any significant change on the bursting strength of the film. Incorporation of lignin considerably improved the light barrier properties of the films. Fourier transform infrared spectroscopy study of films suggested the existence of hydrogen bonding between lignin–alginate in the presence of plasticizers. In addition, EPC plasticized film displayed highest thermal stability, as confirmed by thermogravimetric analysis. Further studies demonstrated that plasticizers significantly affected the physico-chemical properties of the blended films. In conclusion, lignin–alginate film plasticized with EPC presented better physico-mechanical and light barrier properties which could be used in packaging and coating applications.     

Effects of co‐plasticization of acetyl tributyl citrate and glycerol on the properties of starch/PVA films

Starch/polyvinyl alcohol (PVA) nanocomposite films by film blowing process were successfully obtained. Starch (1700 g), PVA (300 g), and organically modified montmorillonite (OMMT, 200 g) were blended and plasticized with acetyl tributyl citrate (ATBC) and glycerol (GLY) at weight ratios of 0/100, 5/95, 10/90, 15/85, 20/80, and 25/75. The structural, morphology, barrier, mechanical, and thermal properties of the films, as well as molecular interactions in the nanocomposites were analyzed. The 3.98 nm d‐spacing was the highest in starch/PVA nanocomposite films plasticized with ATBC/GLY ratio of 10/90. The film with ATBC/GLY (5/95) had the lowest WVP (3.01 × 10^?10 g m^?1 s^?1 Pa^?1). The longitudinal tensile strength (TS) of starch/PVA nanocomposite films gradually increased from 4.46 to 6.81 MPa with the increase of ATBC/GLY ratios. The T_g steadily increased from 49.2°C to 55.2°C and the ΔH of the nanocomposite films decreased from 81.77 to 51.43 J/g at the presence of ATBC. The addition of ATBC into GLY plasticized starch/PVA/OMMT system enhanced the intermolecular interaction in the nanocomposites. This study proved that ATBC was an excellent compatibilizer in the preparation of starch/PVA/OMMT nanocomposite films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42544.     

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     

Comparison of sorbitol and glycerol as plasticizers for thermoplastic starch in TPS/PLA blends

This article investigates the structure and properties of thermoplastic starch/PLA blends where the TPS phase is plasticized by sorbitol, glycerol, and glycerol/sorbitol mixtures. The blends were prepared using a twin‐screw extruder where starch gelatinization, water removal, and dispersion of TPS into a PLA matrix were carried out sequentially. The plasticizers were added to starch in the first stage of the extruder to allow complete starch gelatinization. The PLA was added at mid‐extruder and thoroughly mixed with the TPS. The plasticizer concentration was varied from 30 to 42% and the TPS content was varied from 27 to 60% on a weight basis. In all investigated blends, the PLA formed the continuous phase and the TPS was the dispersed phase. The viscosity, blend morphology, tensile mechanical properties as well as the thermal properties of the materials were measured. It was found that the glycerol/sorbitol ratio has an important effect on the blend properties. Finer blend morphologies, higher tensile strength and modulus but lower crystallization rate were found for the sorbitol plasticized blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of sorghum wax,glycerin, and sorbitol on physical properties of soy protein isolate films

Sorghum wax, sorbitol, glycerin, and soy protein isolate (SPI) composite films were prepared. Effects of sorghum wax, sorbitol, and glycerin concentrations on various films were evaluated using response surface methodology. All independent variables significantly (P<0.05) affected film water vapor permeability (WVP), tensile strength (TS), elongation at break (E), total color difference, and total soluble matter (TSM). Increasing the sorghum wax concentration decreased WVP and E. As sorbitol content increased in the composite films, WVP and TS increased. Sorbitol had a critical point of 2–5 g/5 g SPI for low values of TSM. The addition of sorbitol contributed more to the properties of the film than did glycerin.