Increasing Plasticizer Content Research Articles

Energy storage application of plasticized biopolymer blend electrolyte doped with ammonium nitrate as H+ provider

Recently, proton-conducting electrolytes for energy storage purposes attracted the focus of many research groups as possible alternatives for Li-based energy storage applications. Natural polymers offer a promising solution to counter the environmental impact of synthetic polymers. In this work proton conducting CS:POZ based natural polymer electrolytes were plasticized with glycerol (GL) to improve the ion conductivity and increase the free ion percentage. The films of CS:POZ:NH4NO3 electrolyte were prepared using the casting technique. The plasticizers were changed from 9 to 36 wt%. The FTIR method revealed ion interaction among polymer, salt, and plasticizer. The deconvolution of FTIR band associated with NO3 anion was used to calculate the ion transport parameters (ITPs). It was found that the free ion contour area was enhanced by increasing plasticizer concentration. The EIS plot fitted with equivalent circuit elements was used to determine the DC conductivity and ITPs. The dominancy of ion species was examined using TNM measurement. The safety region for energy storage device (ESD) application was found from the LSV examination. The activated carbon was used to manufacture the electrodes for ESD application. The cyclic voltammetry (CV) investigation found that the capacitances of the ESD influenced by scan rates.

Particle mobility and macroscopic magnetorheological effects for polyurethane magnetic elastomers.

The relationship between the particle mobility and magnetorheological effect was investigated for polyurethane magnetic elastomers containing carbonyl iron particles with various cross-linking densities or plasticizer concentrations. The storage modulus at 0 mT increased and the on-field modulus at 500 mT decreased with the cross-linking density. The critical magnetic field where the storage modulus starts to rise up increased with the cross-linking density, indicating that the movement of magnetic particles is depressed by the cross-linking points of the polyurethane network. Magnetic elastomers with various plasticizer concentrations revealed that the storage modulus at 0 mT decreased and the on-field modulus at 500 mT increased with the plasticizer concentration. The critical magnetic field decreased with increasing plasticizer concentration, indicating that a dense polyurethane network prevents magnetic particles from moving. It was found that the change in the modulus due to the magnetic field can be scaled by the storage modulus at 0 mT as well as the critical magnetic field. Thus, there is a certain correlation between the macroscopic modulus of elasticity (storage modulus at 0 mT) and the microscopic mobility of magnetic particles reflected in the critical magnetic field.

Influence of rice husk ash and wollastonite on plasticizer migration in polyvinyl chloride system

AbstractThe influence of rice hull ash and wollastonite on the migration problem of plasticizer EDOS from polyvinyl chloride (PVC) has been studied. The methods of optical interferometry, IR spectroscopy, viscometry, SEM and EDX were used to study the mutual solubility and diffusion mobility in the PVC‐EDOS system in the presence fillers and without them, as well as the phase structure of plasticized filled systems. It is shown that in a fully compatible PVC‐EDOS system, a diffusion mixing mechanism is observed, and the interdiffusion coefficients increase from 10−8 to 10−6 (cm2/s) with increasing plasticizer concentration. The introduction of a dispersed filler somewhat reduces the interdiffusion coefficients. The sorption of the plasticizer on the surface of the dispersed filler has been established, which leads to a decrease in the migration of EDOS from the composition. It was found that the introduction of wollastonite leads to a smaller increase in viscosity and an improvement in the technological properties of the system. And the introduction of environmentally neutral rice husk ash reduces the migration of the plasticizer and improves the stability of the composition during operation, which also has a positive effect on the environmental friendliness of this system.

Photo-Electrical Tandem of Modulated Polyvinyl Alcohol Based Plasticized Solid Polymer Electrolyte Nanocomposite Films: Effect of Propylene Carbonate Contents

Plasticized solid polymeric electrolyte nanocomposites based on polyvinyl alcohol (PVA) incorporating Cs2CuO2 nanoparticles (NPs), electrolyte salt (LiClO4) and plasticizer (PC) were prepared via solution casting technique. The dynamic light-scattering histogram revealed that the prepared Cs2CuO2 NPs have a size in the range of 80-120 nm. The interaction between different components in PVA/Cs2CuO2/LiClO4-PC films (plasticized PVA-SPEs) were probed by FTIR, while the surface and structure were evaluated by SEM and XRD, which indicate to amorphous nature of plasticized PVA-SPEs. The thermal behavior of films was measured via TGA, where a partial decrease in the thermal stability of films was noticed with an increase of PC content in the PVA-SPEs. The highest conductivity achieved is 9.56X10-5 S/cm for PVA-SPEs containing 8wt% PC at 298K. The plasticized PVA-SPEs exhibited higher specific capacitance by two folds and photovoltaic efficiency by three folds compared to pure PVA matrix.

Magnesium ion conducting biopolymer blend-based electrolyte for energy storage application: Electrochemical characteristics

A casting technique was employed to produce plasticized magnesium ion conducting biopolymer blend electrolytes. Chitosan (CS) and polyvinyl alcohol (PVA) were used to deliver polymer blends, and 50 wt.% of magnesium nitrate (Mg(NO3)2) was incorporated as the source for Mg2+ ions supply. The CS:PVA:Mg(NO3)2 system was subjected to different concentrations of glycerol plasticizer to improve its ion conductivity. To assess their suitability as energy storage materials, the electrochemical characteristics of the fabricated films were examined employing broad methodologies. Distinguished improvement in dielectric constant was observed upon increasing plasticizer concentration. The appearance of relaxation peak in tanδ-M'' spectra and their asymmetric shape reveals the non-Debye relaxation process. The biopolymer blend electrolyte, with a plasticizer content of 55 wt.%, exhibited the highest DC conductivity, measuring 7.34 × 10−5 S.cm−1. In terms of potential stability, linear sweep voltammetry (LSV) analysis revealed a value of 2.34 V for this particular electrolyte. A non-Faradaic (capacitive) response to cyclic voltammetry (CV) is displayed, and there is no redox peak. The selected scan rate influenced the shape of the CV curves. When scan rates of 20 mV/s and 100 mV/s were employed, specific capacitance values of 5.41 and 16.46 F/g were determined. The stability of an electrochemical double-layer capacitor, which serves as an energy storage device, was evaluated by employing a charging-discharging technique and the electrode separator made of the most conducting sample. The results show promise for the potential application of the current plasticized magnesium ion-conducting biopolymer blend electrolyte in energy storage devices.

Insight into the Effect of Glycerol on Dielectric Relaxation and Transport Properties of Potassium-Ion-Conducting Solid Biopolymer Electrolytes for Application in Solid-State Electrochemical Double-Layer Capacitor.

The increased interest in the transition from liquid to solid polymer electrolytes (SPEs) has driven enormous research in the area polymer electrolyte technology. Solid biopolymer electrolytes (SBEs) are a special class of SPEs that are obtained from natural polymers. Recently, SBEs have been generating much attention because they are simple, inexpensive, and environmentally friendly. In this work, SBEs based on glycerol-plasticized methylcellulose/pectin/potassium phosphate (MC/PC/K3PO4) are investigated for their potential application in an electrochemical double-layer capacitor (EDLC). The structural, electrical, thermal, dielectric, and energy moduli of the SBEs were analyzed via X-ray diffractometry (XRD), Fourier transforms infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS), transference number measurement (TNM), and linear sweep voltammetry (LSV). The plasticizing effect of glycerol in the MC/PC/K3PO4/glycerol system was confirmed by the change in the intensity of the samples' FTIR absorption bands. The broadening of the XRD peaks demonstrates that the amorphous component of SBEs increases with increasing glycerol concentration, while EIS plots demonstrate an increase in ionic conductivity with increasing plasticizer content owing to the formation of charge-transfer complexes and the expansion of amorphous domains in polymer electrolytes (PEs). The sample containing 50% glycerol has a maximal ionic conductivity of about 7.5 × 10-4 scm-1, a broad potential window of 3.99 V, and a cation transference number of 0.959 at room temperature. Using the cyclic voltammetry (CV) test, the EDLC constructed from the sample with the highest conductivity revealed a capacitive characteristic. At 5 mVs-1, a leaf-shaped profile with a specific capacitance of 57.14 Fg-1 was measured based on the CV data.

The influence of forming factors on physical characteristics of hollow filter rod using water vapor forming method

This paper designed a hollow filter rod using cellulose diacetate as the raw material. A combination method involving single factor test and orthogonal test was used to analyze the impact of forming factors on physical characteristics. The results showed that the circumference of filter rods was negatively related to vapor pressure. The hardness was both positively connected with vapor pressure and tow-filling amount, while it increased initially and then reduced with the increase of plasticizer content. The roundness and weight varied little with vapor pressure. However, roundness was associated with plasticizer content and negatively associated with tow-filling amount. Besides, weight was positively associated with both plasticizer content and tow-filling amount. The orthogonal test results revealed that the tow-filling amount was the most important factor influencing the performance of filter rods, with vapor pressure and plasticizer content being secondary considerations. The best parameter combination was vapor pressure of 0.18 MPa, plasticizer content of 20%, and tow-filling amount of 1.19 g. The improved cigarette filter rod had a hardness of 92.07%, which was 5.61% greater than the previous value and only 0.08% higher than the optimal value. The enhanced performance of filter rods was attributable to three-dimensional entangled structures formed by cellulose diacetates and rational arrangement of tows and voids.

Enhanced migration of plasticizers from polyvinyl chloride consumer products through artificial sebum

In the present study, the migration of plasticizers from modeled and commercial polyvinyl chloride (mPVC and cPVC, respectively) to poly(dimethylsiloxane) via artificial sebum was assessed to mimic the dermal migration of plasticizers. In addition, the various factors affecting migration of phthalic acid esters (PAEs) from diverse PVC products were investigated. The migrated mass and migration ratio of PAEs increased but the migration rate decreased over time. The migration rate increased with sebum mass, contact time, and temperature but decreased under higher pressure. Low-molecular-weight PAEs (dimethyl phthalate and diethyl phthalate) migrated in higher amounts than high-molecular-weight PAEs (dicyclohexyl phthalate [DCHP] and diisononyl phthalate [DINP]). Diffusion of all PAEs in mPVC increased with temperature, with diffusion coefficients ranging from 10−13 to 10−15, 10−12 to 10−14, and 10−10 to 10−12 cm2·s−1 at 25 °C, 40 °C, and 60 °C, respectively; the enthalpy of activation ranged between 127 and 194 kJ·mol−1. Moreover, migration depended on total PAE content of the product, as the diffusion coefficient for DINP in cPVC (softer PVC) was approximately three orders of magnitude higher than that for DINP in mPVC (harder PVC); this may be due to the increase in free volume with increasing plasticizer content. Finally, the daily exposure doses of the plasticizers were estimated. These findings will be helpful for estimating dermal exposure risk.

Rheology of nano ZnO - Hydroxypropyl Methylcellulose (HPMC) based suspensions and structural properties of resulting films

Effect of polyethylene glycol (PEG) and ZnO nanoparticles concentration on rheological properties of the hydroxypropyl methylcellulose (HPMC) based film forming suspensions (FFS) and, on the structural properties of the resulting films were characterized. Rheological properties of FFS were not significantly affected by PEG concentration and ZnO NPs incorporation. Intrinsic viscosity [η] of aqueous HPMC solution obtained from extrapolation of Huggins and Kraemer plot was 0.115–0.118 (L/g). Coating thickness calculated as a function of coating solution viscosity, concentration and draining time for strawberry coating was 1.26–1.49 μm. Tensile strength (TS) of HPMC film decreased while water vapour permeability (WVP) increased with increasing PEG concentration. Elongation at break (%E) increased up to 25% PEG concentration and decreased afterward. Incorporation of ZnO NPs improved the tensile strength and barrier properties of HPMC film. Relaxation percentage and stress decay rate increased with increasing plasticizer concentration while decreased with incorporation of ZnO NPs. • Rheological behaviour of aqueous HPMC solution (4% w/v) was Newtonian. • Calculated Intrinsic viscosity [η] of aqueous HPMC solution was 0.115–0.118 (L/g). • Relaxation % and stress decay rate showed positive correlation with PEG concentration. • Added ZnO nanoparticles improves the HPMC film properties.

Development of Almond gum/alginate composites to enhance the shelf-life of post-harvest Solanum Lycopersicum L

Almond Gum/alginate composite (AG/AL) composites namely A1, A2 and A3 were prepared and their physicochemical properties were evaluated. The measured film thickness, moisture and solubility were indistinguishable among the films whereas water contact angle analysis shows that A2 (83.8±1.65) and A3 (86.2±3.19) film has high hydrophobicity than A1 (58.4±3.21). By increasing plasticizer concentration from 0.4% to 0.66%, elongation was increased from 30 to 53 % whereas tensile strength (3.16 to 1.90 Mpa) and water vapor transmission rate (WVTR) decreased from 212 to 160 g/m2/24hr. FT-IR analysis shows that the edible film has O-H, C-H, C=O and –COO functional groups and SEM analysis reveals that the prepared film has even surface due to the strong interaction between polymer and plasticizer. TGA results show major weight loss at 100°C, 190-220°C and 350°C-400°C due to the dehydration/decomposition of water molecules and carbon containing functional groups. Film solution was used as an edible coating in tomatoes and weight loss (WL), titratable acidity (TA), Total soluble solids (TSS), ascorbic acid content (AAC) and anti-microbial activity were determined. The WL analysis shows a significant delay in decay of coated tomatoes over 40 days of storage time whereas control tomatoes decayed on day 25. TA and TSS test confirms that the coating can significantly (P<0.05) prevent the acidity level of tomaotes. Furthermore, the AG/AL coating has great activity against E. coli, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus. Therefore, the present study confirms that AG/AL has superior properties and potential as edible films or coating.

Comparative Effect of Different Plasticizers on Barrier, Mechanical, Optical, and Sorption Properties of Hydroxypropyl Methylcellulose (HPMC)–Based Edible Film

Identifying ideal plasticizer is pivotal to develop a biopolymer-based edible films for food packaging. The effect of different plasticizers (glycerol, polyethylene glycol, sorbitol) on the mechanical, water vapor barrier, optical, and moisture sorption properties of hydroxypropyl methylcellulose (HPMC) -based flexible films was examined in this study. Mechanical properties and water vapor permeability (WVP) of films were determined using standard ASTM methods. Moisture sorption isotherm (MSI) for different HPMC films were obtained thermogravemitically and seven sorption models were fitted to experimental sorption data through nonlinear regression using curve fitting tool in MATLAB R2015b and goodness of fit of these models was compared based on Akaike information criterion (AIC). GAB model was used to determine the monolayer moisture content and heat of sorption of different films. Plasticizing efficacy of different plasticizers was significantly different for HPMC film in studied concentration range. Water vapor permeability (WVP) for native HPMC film was 0.451 g mm/kPa m2 h, which further increased to 0.972, 0.890, and 0.615 g mm/kPa m2 h when 25% (w/w of HPMC) glycerol, PEG, and sorbitol were added as plasticizers, respectively. GAB model showed an increase in monolayer moisture (M0) content with increasing plasticizer concentration and the highest M0 value was observed for glycerol-plasticized film. Added plasticizers were found to be effective in providing desirable flexibility in terms of elongation to HPMC film which is beneficial for coating and shrink wrap packaging application but adversely affect the tensile strength and transparency of film. Henderson and Oswin models were selected as the best fit model to the experimental sorption data based on AIC values. The findings from the current study would serve in selection of suitable plasticizer for HPMC-based film/coating in food packaging applications.

Preparation and Characterization of Whey Protein Isolate-based Coating Solutions and Coated Papers with Different Plasticizers

Whey protein isolates (WPIs) are a byproduct of cheese and milk processing. WPI-based films offer transparency and good gas barrier properties at a low relative humidity, along with numerous different functional groups. However, they are hydrophilic, which restricts their use, and feature poor mechanical properties like brittleness. In this study, we explored the properties of WPI based coating materials depending on the type and contents of plasticizers, to use as a barrier coating materials for paper. Coating materials of WPI/glycerol (GY) and WPI/sorbitol (SO) with different plasticizer contents were prepared by solution blending. These materials were then coated on the surface of paper. The morphological structure, burst strength, tensile index, elongation at break, air permeability, and surface properties of the WPI/GY and WPI/SO-coated papers were investigated and compared based on the type and content of plasticizer. Compared to the WPI/GY-coated papers, the cracking of coating layers on the WPI/SO-coated papers was mitigated with increasing SO content in the WPI matrix. The WPI/SO-coated papers exhibited a higher tensile index, elongation at break, and air barrier than the WPI/GO-coated papers. Surface property analysis revealed that the hydrophilicity of both coated papers increased with increasing plasticizer content. However, further research is needed to reduce the hydrophilicity in WPI-coated papers and improve the compatibility between WPI and the plasticizer to enable their application in packaging.

Effect of glycerol and sorbitol on the mechanical and barrier properties of films based on pea protein isolate produced by high‐moisture extrusion processing

AbstractDisposable food packaging accounts for a large proportion of the plastic waste in the environment. Bio‐based and biodegradable alternatives could help to reduce plastic pollution but must perform similarly to current synthetic materials. Here, we investigated the effect of two plasticizers (glycerol and sorbitol) on the mechanical and barrier properties of films composed of extruded pea protein isolate. We evaluated physical properties such as tensile strength, elongation at break, moisture content, surface energy, residence time distribution, and gas barrier properties as a function of plasticizer concentration. The flexibility and workability of the films generally increased with higher concentrations of the plasticizer. The residence time distribution (RTD) showed that sorbitol mixtures remained in the extruder longer than glycerol mixtures, exacerbating the loss of quality. Glycerol films generally retained more moisture than sorbitol films and the tensile strength declined with increasing glycerol content, but the elongation at break increased. The polar fraction of the surface energy increased with higher concentrations of sorbitol, indicating that sorbitol is more polar than the pea protein isolate. In terms of barrier properties, both the water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) were higher for films plasticized with sorbitol. Specifically, the OTR for sorbitol‐plasticized films at 50% (vol/vol) was 519 cm3*100 μm/(m2*d*bar) compared to 300 cm3*100 μm/(m2*d*bar) for the glycerol‐plasticized films, and the WVTR for sorbitol‐plasticized films at 50% (vol/vol) was 2633 g*100 μm/(m2*d) compared to 895 g*100 μm/(m2*d) for the glycerol‐plasticized films. For both plasticizers, the WVTR increased with increasing plasticizer concentration. In contrast, the OTR declined with increasing glycerol concentrations, whereas no trend was observed for sorbitol. Our study shows that pea protein isolate is suitable for the manufacture of bio‐based films and confirms that plasticizers influence the resulting mechanical and barrier properties. Further research is necessary to optimize the properties of the films.

Effect of additives on the mechanical properties of bulk polymerized Acrylic using orthogonal test

The effects of different additives on mechanical properties of acrylic were studied by orthogonal test, using methyl methacrylate as raw material, concentration of initiator(azobisisobutyronitrile), plasticizer (Dibutyl Phthalate) and release agent(Stearic Acid) as the influence factors. The results show that: among the three additives, initiator is the most significant factor, which has the greatest impact on the mechanical properties of acrylic. With increasing of initiator content, the tensile strength of acrylic decreases. The effect of plasticizer and release agent on the mechanical properties of acrylic is relatively small. As the increase of plasticizer content, the tensile strength and bending strength decline. Finally, the best ratio of the three additives is initiator=0.06, plasticizer=3.0, release agent=1.0.

Thermal Properties of Plasticized Cellulose Acetate and Its β-Relaxation Phenomenon.

Cellulose acetate (CA), an organic ester, is a biobased polymer which exhibits good mechanical properties (e.g., high Young’s modulus and tensile strength). In recent decades, there has been significant work done to verify the thermal and thermomechanical behaviors of raw and plasticized cellulose acetate. In this study, the thermomechanical properties of plasticized cellulose acetate—especially its -relaxation and activation energy—were investigated. The general thermal behavior was analyzed and compared with theoretical models. The study’s findings could be of special interest, due to the known -relaxation dependency of some polymers regarding mechanical properties—which could also be the case for cellulose acetate. However, this would require further investigation. The concentration of the plasticizers—glycerol triacetate (GTA) and triethyl citrate (TEC)—used in CA ranged from 15 to 40 wt%. DMTA measurements at varying frequencies were performed, and the activation energies of each relaxation were assessed. Increasing plasticizer content first led to a shift in -relaxation temperature to highervalues, then reached a maximum before declining again at higher concentrations. Furthermore, the activation energy of the -relaxation constantly rose with increases in plasticizer content. The trend in the -relaxation temperature of the plasticized CA could be interpreted as a change in the predominant phase of the overlapping -relaxation of the CA itself and the -relaxation of the plasticizer—which appears in the same temperature range. The plasticizer used (GTA) demonstrated a higher plasticization efficiency than TEC. The efficiencies of both plasticizers declined with increasing plasticizer content. Additionally, both plasticizers hit the saturation point (in CA) at the lowest studied concentration (15 wt%).

Influence of monomer type, plasticizer content, and powder/liquid ratio on setting characteristics of acrylic permanent soft denture liners based on poly(ethyl methacrylate/butyl methacrylate) and acetyl tributyl citrate.

We evaluated the influence of monomer type, plasticizer content, and powder/liquid (P/L) ratio on the setting characteristics of light-cured acrylic permanent soft denture liners based on poly(ethyl methacrylate/butyl methacrylate). Two monomers, iso-butyl methacrylate (i-BMA) and 2-ethylhexyl methacrylate (2-EHMA), that contained various concentrations of the plasticizer acetyl tributyl citrate (ATBC) and trace amounts of the photo initiator and reducing agent were used. The P/L ratio was 1.0 or 1.2. The gelation time was measured using a controlled stress rheometer. Materials with i-BMA had shorter gelation times than those for materials with 2-EHMA. The gelation time increased exponentially with increasing plasticizer content. A higher P/L ratio led to a shorter gelation time. The effects of monomer type and plasticizer content were larger than that for the P/L ratio. These results show that 2-EHMA is a suitable monomer for soft denture liners and that the setting characteristics can be controlled via ATBC content.

Effect of polycarboxylate superplasticizer on fluidity and rheology of cement slurry containing silica fume

The effect of polycarboxylate superplasticizer on the fluidity and rheology of cement - silica fume - water paste was investigated. The changes of dispersion degree, yield stress and plastic viscosity of paste with different superplasticizer content were analyzed. The results show that the rheological properties of paste with different superplasticizer content conform to Herschel-Bulkley model. The shear thinning of the slurry is manifested as a typical yielding pseudoplastic fluid characteristic. When the content of superplasticizer is less than 1.0%, the plastic viscosity and yield stress decrease and the fluidity increase with the increase of plasticizer content. When the content of superplasticizer is more than 1.0%, the yield stress decreases slightly and the plastic viscosity increases with the increase of plasticizer content. The fluidity decreases with the increase of yield stress, and there is a good correlation between them.

Effect of glycerol and sorbitol concentrations on mechanical, optical, and barrier properties of sweet potato starch film

The search to improve the characteristics of biomaterials obtained from natural biopolymers such as starch has led to the use of mixtures of various polymers with plasticizing agents such as glycerol and sorbitol. In this research, the effect of concentration (10, 20, 30, 40 and 50% starch basis) and type of plasticizer (glycerol and sorbitol) on water solubility (WS), total color difference (ΔE), mechanical properties and water vapor permeability (WVP) of films based on sweet potato starch was evaluated. The mechanical properties were determined by the Puncture Strength method, WVP and WS were performed using gravimetric methods, ΔE was determined by a colorimeter. The results showed an inverse relationship between the puncture resistance and ΔE of the films with the concentration of the plasticizers. However, an increase in plasticizer concentration led to an increase in the percentage of elongation, WS, and WVP of sweet potato starch films. The highest values for percentage elongation and WVP were found in films plasticized with glycerol. Sweet potato starch can be used for the development of film for edible candy wrappers and edible coatings fresh fruit and vegetables.

Improvement in mechanical properties and biodegradability of PLA using poly(ethylene glycol) and triacetin for antibacterial wound dressing applications.

Wound is among the most common injuries. A suitable wound dressing has a significant effect on the healing process. In this study, a porous wound dressing was prepared using poly (lactic acid) (PLA) and two plasticizers, polyethylene glycol (PEG) and triacetin (TA), through solvent casting method. For antibacterial activities, metronidazole was incorporated in the structure. The morphology was investigated by scanning electron microscopy (SEM). In addition, the effect of plasticizers ratio on porosity growth was evaluated. It was also observed that each had a unique effect on the structure's porosity. The mechanical properties confirmed the effect of both plasticizers on increasing polymer softness and flexibility, and the most similar formulations to human skin in terms of mechanical properties were introduced. According to the results, TA had stronger effect on mechanical properties. The differential scanning calorimetry (DSC) showed the effect of increasing plasticizer concentration on crystalline structure and Tm reduction of PLA. The water contact angle measurement showed that both plasticizers enhanced hydrophilic characteristics of PLA, and this effect was weaker in PEG-containing formulations. The in vitro degradation study showed biodegradability, as a desirable property in wound dressing. Results suggested that higher degradation can be obtained by both plasticizers at the same time. The results also showed that PEG was more effective in enhancing water absorbency. In vitro drug release study indicated an explosive release and the highest amount was 85% over 186h. The antibacterial activity test confirmed the effectiveness of the drug in preventing bacterial growth in the drug-containing formulations, while it showed the antibacterial property of TA. MTT assay was performed and the cellular toxicity of the formulations was checked and those that revealed the least toxicity were introduced.

Effects of plasticizer type and concentration on rheological, physico-mechanical and structural properties of chitosan/zein film

The purpose of this study was to evaluate the effect of plasticizer type (glycerol, PEG-400, and sorbitol) and concentration (0%, 15%, 30% and 45%, w/w dry polymer weight) on rheological and physico-mechanical and structural properties of chitosan/zein blend film. Based on the analysis of rheological properties of chitosan/zein film-forming solutions, all film-forming solutions exhibited non-Newtonian behavior. The flow index of film-forming solution increased and apparent viscosity decreased with the increase of plasticizer concentration. The storage modulus (G′) and the loss modulus (G″) decreased when plasticizer was added. The permeability of films increased significantly with the increase of plasticizer concentration, but the C/Z-P film (plasticized chitosan/zein film with PEG-400) had better barrier performance compared with the other two. The C/Z-P film had better mechanical properties and light transmission. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) revealed chitosan and zein had good compatibility due to the addition of the plasticizer, and crystallinity decreased with the increase of plasticizer concentration.