Bio‐nanocomposite films based on cellulose nanocrystals filled polyvinyl alcohol/chitosan polymer blend

Bio‐nanocomposite films based on polyvinyl alcohol/chitosan (PVA/CS) polymeric blend and cellulose nanocrystals (CNC) were prepared by casting a homogenous and stable aqueous mixture of the three components. CNC used as nanoreinforcing agents were extracted at the nanometric scale from sugarcane bagasse via sulfuric acid hydrolysis; then they were characterized and successfully dispersed into a PVA/CS (50/50, w/w) blend to produce PVA/CS–CNC bio‐nanocomposite films at different CNC contents (0.5, 2.5, 5 wt %). Viscosity measurement of the film‐forming solutions and structural and morphological characterizations of the solid films showed that the CNC are well dispersed into PVA/CS blend forming strong interfacial interactions that provide an enhanced load transfer between polymer chains and CNC, thus improving their properties. The obtained bio‐nanocomposite films are mechanically strong and exhibit improved thermal properties. The addition of 5 wt % CNC within a PVA/CS blend increased the Young's modulus by 105%, the tensile strength by 77%, and the toughness by 68%. Herein, the utilization of Moroccan sugarcane bagasse as raw material to produce high quality CNC has been explored. Additionally, the ability of the as‐isolated CNC to reinforce polymer blends was studied, resulting in the production of the aforementioned bio‐nanocomposite films with improved properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42004.     

Properties of compatibilized polylactide blend films with gelatinized corn and tapioca starches

Blend films containing two types of starch, various amounts of methylenediphenyl diisocyanate (MDI), and polylactide were prepared. The effects of MDI level and starch type on the tensile, thermal, and morphological properties of these films were investigated. The MDI amount was varied from 0 to 10 wt % on the basis of gelatinized starch (GS) content, whereas two types of starch (corn and tapioca) were added as fillers. In this study, the blend films were hot‐mixed at 180°C by an internal batch mixer and then compression‐molded to form test specimens. The results show that the addition of MDI as a compatibilizer led to an increase in the tensile properties compared with the uncompatibilized films. Furthermore, the thermal properties indicated some improving interfacial adhesion between the two phases, as evidenced by the morphological results. These behaviors were observed in the blends with both gelatinized tapioca starch and gelatinized corn starch. The different types of starch had no effect on the glass‐transition and melting‐temperature shifts, including water absorption of the blend films. On the other hand, the mechanical properties of the blends with gelatinized corn starch were higher than those of the others. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of halloysite nanotubes and kaolin loading on the tensile,swelling, and oxidative degradation properties of poly(vinyl alcohol)/chitosan blends

[Halloysite nanotubes (HNT)]‐filled and kaolin filled composite films based on poly(vinyl alcohol) (PVA)/chitosan (CS) blend were prepared via solution casting method. Tensile properties, fracture morphology, FTIR spectra, thermal stability, swelling properties, moisture absorption, and oxidative degradation of the composite films were investigated. Addition of 0.5 wt% of filler led to the optimum tensile properties of the films. Increased roughness and tearing in the fracture surface morphology supported the tensile results. The FTIR results indicated there were physical interactions present in the composite films. Thermal stability of the composite films differed slightly where PVA/CS/HNT composite films showed better thermal stability than PVA/CS/kaolin composite films. Moreover, the presence of HNT and kaolin fillers in the blend reduced the swelling and moisture absorption properties of the films. Finally, the composite films were degraded by using Fenton's reagent. Degradation percentage of the composite films decreased with increasing filler loading. J. VINYL ADDIT. TECHNOL., 19:55–64, 2013. © 2013 Society of Plastics Engineers     

Physical properties of water‐borne polyurethane blended with chitosan

Water‐borne polyurethanes based on 4,4‐diphenylmethane diisocyanate, poly(butylene adipate), and chain extender N‐methyldiethanolamine (MDEA) that provided tertiary amine groups were synthesized. The polyurethane–chitosan (PU/CS) blends can be dissolved in the acetic acid and cast into films. The mechanical properties including tensile strength and elongation, as well as the water absorption and thermal properties of the PU/CS films were evaluated. The tensile strength increased with the increased amount of chitosan, but the elongation decreased accordingly. The chitosan in the blends promoted the water absorption. Chitosan was more thermally‐stable than PU, as shown in the thermal gravity analysis. Chitosan also had higher crystallinity, as demonstrated by differential scanning calorimetry. The blends were partial compatible mixtures, based on the data obtained from a dynamic mechanical analysis. Biocompatibility test was conducted utilizing immortalized rat chondrocytes (IRC). After IRC were seeded onto the PU/CS films for 1.5 and 120 h, the number of cells was counted and the morphology of cells was observed by light microscopy and scanning electron microscopy. Blends containing 30% chitosan had more cells attached initially. However, the blends containing more than 70% chitosan appeared to promote the cell proliferation. IRC were round on PU/CS films with more PU, but spread when the chitosan content in blends was higher. Overall, PU/CS films with more chitosan had better mechanical properties as well as biocompatibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2683–2689, 2007     

Influence of starch and glycerol on the properties of chitosan by positron annihilation spectroscopy

Two types of chitosan (CS), α and β, were blended with different concentrations of starch and cast to obtain films. The addition of 1% glycerol was used as a plasticizer to increase film flexibility. The properties of the obtained films were studied by positron annihilation lifetime spectroscopy, X‐ray diffraction, and scanning electron microscopy. The results indicate that pure β‐CS had smaller size free‐volume holes with high fractions than pure α‐CS; this was attributed to the difference in bonding of main chains in β‐CS. The addition of starch (>20% up to 50%) reduced the size of the free‐volume holes and increased their fraction because of the close packing of chain segments. The effect of 1% glycerol to the CS starch blends indicated that some modification took place. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ionic self‐assembly and characterization of a polysaccharide‐based polyelectrolyte complex of maleic starch half‐ester acid with chitosan

A novel polysaccharide‐based polyelectrolyte complex was formed via ionic self‐assembly (ISA) of a carboxylic derivative of starch, maleic starch half‐ester acid (MSA), with chitosan (CS) and precipitated from aqueous solution. Both Fourier transform infrared (FTIR) spectroscopy and elementary analysis results showed that there was CS in the complex. Thermogravimetric analysis (TGA) showed that the thermal resistance of the complex was higher than that of two components and the corresponding blend. X‐ray diffraction (XRD) analysis result revealed that the complex was amorphous, whereas its components were semi‐crystalline. In addition, the drug release behavior of the complex that contains 5‐fluorouracil behaved pH‐responsive. All the experimental results verified the complex was composed of MSA and CS, and also indicated that the driving force for the self‐assembly of the complex was predominantly the electrostatic interactions between two oppositely charged polyelectrolytes, cationic CS, and the anionic MSA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Photobiodegradation of low‐density polyethylene/banana starch films

The effects of the starch content, photosensitizer content, and compatibilizer on the photobiodegradability of low‐density polyethylene (LDPE) and banana starch polymer blend films were investigated. The compatibilizer and photosensitizer used in the films were PE‐graft‐maleic anhydride (PE‐g‐MA) and benzophenone, respectively. Dried banana starch at 0–20% (w/w) of LDPE, benzophenone at 0–1% (w/w) of LDPE, and PE‐g‐MA at 10% (w/w) of banana starch were added to LDPE. The photodegradation of the blend films was performed with outdoor exposure. The progress of the photodegradation was followed by determining the carbonyl index derived from Fourier transform IR measurements and the changes in tensile properties. Biodegradation of the blend films was investigated by a soil burial test. The biodegradation process was followed by measuring the changes in the physical appearance, weight loss, and tensile properties of the films. The results showed that both photo‐ and biodegradation rates increased with increasing amounts of banana starch, whereas the tensile properties of the films decreased. The blends with higher amounts of benzophenone showed higher rates of photodegradation, although their biodegradation rates were reduced with an increase in benzophenone content. The addition of PE‐g‐MA into polymer blends led to an increase in the tensile properties whereas the photobiodegradation was slightly decreased compared to the films without PE‐g‐MA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2725–2736, 2006     

Enhancement of water barrier properties of cassava starch-based biodegradable films using silica particles

Biodegradable films are used in a variety of applications, including packaging. However, their use is limited due to their high moisture and water sensitivity. In this work, cassava starch (CS) was blended with poly(vinyl alcohol) (PVA). Silica particles (SiO₂) were incorporated to increase the hydrophobicity of the blend by intermolecular interaction through hydrogen bonding between the three components. Instead of a plasticizer or crosslinker, a small amount of triethylamine was added to eliminate residual acetate groups in PVA. The miscibility of CS and PVA phases was confirmed by smooth fracture surfaces and a single glass transition temperature. When SiO₂ content was below 5% (wt), the particles were well dispersed in a continuous phase of polymer matrix. At this loading of SiO₂, the increase in tensile strength was as high as 170% and in elongation-at-break, 250%. All loadings of SiO₂ increased thermal stability of the blend films because silanol groups on the surface of SiO₂ particles formed effective interfacial interactions with hydroxyl groups of the polymers. These interactions also prevented the ingress of water molecules, significantly increasing the hydrophobicity of the films. The water contact angle increased as high as 113° and moisture absorbency and water solubility were low. These highly hydrophobic, photodegradable, biodegradable CS/PVA/SiO₂ films show great potential as a low-cost, eco-friendly material.

     

Structure and properties of casting films blended with starch and waterborne polyurethane

A series of casting films blended from starch and waterborne polyurethane (STPU) in aqueous solution were prepared. The structure and properties of the films were investigated by infrared spectroscopy, ultraviolet spectroscopy, scanning electron micrography, strength test, thermogravimetric analysis, and different scanning calorimetry. The results showed that the tensile strength and modules of air‐dried STPU blend films increased with the increase of starch content, while elongation decreased. When starch content was in the range from 80 to 90 wt %, the blend films showed significantly higher tensile strength, breaking elongation, water resistivity, and light transmittance than that of pure starch film, resulting from the miscibility between starch and waterborne polyurethane. Moreover, the STPU films containing 90 wt % starch have higher thermal stability than pure waterborne polyurethane film, and their light transmittance was close to the polyurethane, due to the existence of a strong intermolecular hydrogen bonding between starch and polyurethane. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2006–2013, 2001     

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     

Compatibilizing effect of starch‐grafted‐poly(L‐lactide) on the poly(ε‐caprolactone)/starch composites

The poly(ε‐caprolactone) (PCL)/starch blends were prepared with a coextruder by using the starch grafted PLLA copolymer (St‐g‐PLLA) as compatibilizers. The thermal, mechanical, thermo‐mechanical, and morphological characterizations were performed to show the better performance of these blends compared with the virgin PCL/starch blend without the compatibilizer. Interfacial adhesion between PCL matrix and starch dispersion phases dominated by the compatibilizing effects of the St‐g‐PLLA copolymers was significantly improved. Mechanical and other physical properties were correlated with the compatibilizing effect of the St‐g‐PLLA copolymer. With the addition of starch acted as rigid filler, the Young's modulus of the PCL/starch blends with or without compatibilizer all increased, and the strength and elongation were decreased compared with pure PCL. Whereas when St‐g‐PLLA added into the blend, starch and PCL, the properties of the blends were improved markedly. The 50/50 composite of PCL/starch compatibilized by 10% St‐g‐PLLA gave a tensile strength of 16.6 MPa and Young's modulus of 996 MPa, respectively, vs. 8.0 MPa and 597 MPa, respectively, for the simple 50/50 blend of PCL/starch. At the same time, the storage modulus of compatibilized blends improved to 2940 MPa. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Studies of chitosan. I. Preparation and characterization of chitosan/poly(vinyl alcohol) blend films

Various blending ratios of chitosan/poly (vinyl alcohol) (CS/PVA) blend films were prepared by solution blend method in this study. The thermal properties and chemical structure characterization of the CS/PVA blend films were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier transform infrared (FTIR). Based upon the observation on the DSC thermal analysis, the melting point of PVA is decreased when the amount of CS in the blend film is increased. The FTIR absorption characteristic is changed when the amount of CS in the blend film is varied. Results of X‐ray diffraction (XRD) analysis indicate that the intensity of diffraction peak at 19° of PVA becomes lower and broader with increasing the amount of CS in the CS/PVA blend film. This trend illustrates that the existence of CS decreases the crystallinity of PVA. Although both PVA and CS are hydrophilic biodegradable polymers, the results of water contact angle measurement are still shown as high as 68° and 83° for PVA and for CS films, respectively. A minimum water contact angle (56°) was observed when the blend film contains 50 wt % CS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Structural changes and their effect on mechanical properties of silk fibroin/chitosan blends

Silk fibroin/chitosan blend films were prepared by the solvent casting method. Miscibility between silk fibroin and chitosan was examined by dynamic mechanical thermal analysis. Structural changes of silk fibroin by the addition of chitosan were investigated by IR spectroscopy. The conformational transition of silk fibroin from random coil form to β‐sheet structure induced by blending with chitosan resulted in the increase of crystallinity and density of the blend films. The blend film containing 30 wt % chitosan exhibited a maximum increase in crystallinity and density. It was found that the tensile strength and initial tensile modulus of blend films were greatly enhanced with increasing the chitosan content and showed a maximum value at the composition of 30 wt % chitosan. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2571–2575, 1999     

Graphene oxide reinforced chitosan/polyvinylpyrrolidone polymer bio‐nanocomposites

Bio‐nanocomposite films based on chitosan/polyvinylpyrrolidone (CS/PVP) and graphene oxide (GO) were processed using the casting/evaporation technique. It has been found that the three components of bio‐nanocomposites can be easily mixed in controlled conditions enabling the formation of thick films with high quality, smooth surface and good flexibility. Structural and morphological characterizations showed that the GO sheets are well dispersed in the CS/PVP blend forming strong interfacial interactions that provide an enhanced load transfer between polymer chains and GO sheets thus improving their properties. It has been found that the water resistance of the CS/PVP blend is improved, and the hydrolytic degradation is limited by addition of 0.75 and 2 wt % GO. The modulus, strength, elongation and toughness of the bio‐nanocomposites are together increased. Herein, the steps to form new bio‐nanocomposite films have been described, taking the advantage of the combination of CS, PVP and GO to design the aforementioned bio‐nanocomposite films, which allow to have extraordinary properties that would have promising applications as eventual packaging materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41042.     

Development of biopolymer composite films based on chicory extract reinforced polyvinyl alcohol/chitosan blend via green approach for flexible optoelectrical devices

Biopolymer blend composite films based on polyvinyl alcohol (PVA) and chitosan (CS) incorporated with varying amounts of chicory extract (CE) have been developed by the green solution casting technique. The impact of CE content on structural, thermal, mechanical and electrical properties was thoroughly examined. The existence of intermolecular interactions in the blend composite was confirmed by Fourier-transform infrared and ultraviolet spectroscopy. The x-ray diffraction pattern proved the successful preparation of PVA/CS/CE composite film. The scanning electron microscopy images of the composites showed shape and grain size for the different bio-filler contents. The thermal transition temperature of the blend composites was significantly improved by the addition of CE extract deduced from differential scanning calorimetry. The dielectric study showed that the permittivity remarkably increases with decreasing frequency and maximum dielectric constant was observed for 15 wt% loading. The activation energy obtained from the AC conductivity decreased as the temperature increased. The addition of CE extract improved the hardness and tensile strength of the PVA/CS blend composite in comparison with a pristine pure blend. The controllable mechanical, thermal, optical, and electrical characteristics of the PVA/CS blend composite suggest that it might be an attractive optical material for the advancement of futuristic flexible-type optoelectronic and energy storage systems.     

Characterization of gamma irradiated concentrated aqueous solutions of chitosan/sodium alginate blends and their drug uptake‐release characters

Blends films based on different ratios of concentrated aqueous solutions of chitosan (CS) and sodium alginate (AG) in the presence of 1% of glutaraldehyde, as a cross‐linking agent for chitosan, were prepared by solution casting and then exposed to gamma irradiation. The formed blends were characterized by IR spectroscopic analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The uptake‐release properties of CS/AG blends, taking ketoprofen as an example for drug, were also investigated. DSC thermograms of CS/AG blends revealed good miscibility was sustained between CS and AG. The water uptake and gel content of CS/AG blends was found to decrease by increasing the ratio of AG in the initial solution. The IR spectra indicated the formation of cross‐linking and hydrogen bonding, while the TGA study showed that the CS/AG blends displayed higher thermal stability than pure CS polymer. Based on Fick's law, it was demonstrated that the main parameters affecting the release of ketoprofen drug from the CS/AG blend hydrogels were composition and pH. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Blend films from chitosan and konjac glucomannan solutions

Blend films were prepared by blending 7 wt % konjac glucomannan (KGM) aqueous solution with 2 wt % chitosan (CH) in acetate solution and dried at 40°C for 4 h to obtain the transparent films. Their structure and properties were studied by infrared (IR), wide‐angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). Crystallinities of the blend films decreased with the increase of konjac glucomannan. The thermostability, tensile strength, and breaking elongation of the blend films in dry state were obviously higher than those of both konjac glucomannan and chitosan films. Tensile strength of the dry blend film achieved 73.0MPa when the weight ratio of chitosan to konjac glucomannan was 7:3. The structure analysis indicated that there is a strong interaction between konjac glucomannan and chitosan resulted from intermolecular hydrogen bonds. The water solubility of the blend films was improved by blending with konjac glucomannan, so they have promising applications to soluble antiseptic coating of pills. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 509–515, 2000     

Electrospinning of chitosan/poly(lactic acid) nanofibers: The favorable effect of nonionic surfactant

To improve the electrospinnability of chitosan (CS), a series of nanofiber membrane blends comprised of CS, poly(lactic acid) (PLA), and nonionic surfactant polyoxyethylene nonylphenol ether (TX‐15), were made. Uniform nanofibers with no bead‐like structures were obtained from solutions of 2% TX‐15 with 6% CS(50)/PLA(50). The diameter was between 200 and 300 nm. We found that with increasing TX‐15 in the blend, the nanofibers displayed more hydrophilicity. Compared to CS/PLA nanofibers, the blend polymers with TX‐15 had better tensile mechanical properties. Finally, all cells examined showed high levels of attachment and spreading on CS/PLA/TX‐15 nanofibers with a TX‐15 content of 0～3%. Thus, the nanofibers were nontoxic. In conclusion, adding PLA and TX‐15 to CS via solution‐blending and electrospinning may be an effective way to toughen CS nanofibers and make them more suitable for drug delivery or tissue engineering applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41098.     

Relationship between composition and properties for stable chitosan films containing lipid microdomains

Biocompatible, biodegradable films composed of a hybrid blend of chitosan and egg phosphatidylcholine (ePC) were characterized in terms of composition, morphology, and performance‐related properties. The miscibility between chitosan and ePC for blends of 1 : 0.2 to 1 : 2.5 chitosan : ePC (wt/wt) was examined by differential scanning calorimetry and X‐ray diffraction analysis. The partial miscibility exhibited between chitosan and ePC provided an understanding of the microdomain morphology that was visualized by laser scanning confocal fluorescence microscopy of the films. The stability of the films in physiologically relevant media was assessed by percent weight loss over time. The mechanical properties of the chitosan–ePC films were determined by dynamic mechanical analysis and tensile tests. Interestingly, the dry film composed of a high lipid formulation (1 : 2.5 (wt/wt) chitosan: ePC) had the lowest tensile strength, contained lipid microdomains (10–30 μm in size), and provided the highest degree of stability. Following immersion in phosphate buffer solution, the Young's modulus of the film was found to decrease by more than two orders of magnitude and could be further manipulated by decreasing the lipid content within the film. In this way, relationships between the composition and the physical as well as mechanical properties of the chitosan–ePC blends were established. Furthermore, this study demonstrates the potential usefulness of partially miscible chitosan‐based blends for biomedical purposes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3453–3460, 2007     

Effect of postcrosslinking modification with glutaraldehyde on the properties of thermoplastic starch/poly(vinyl alcohol) blend films

Thermoplastic starch (TPS)/poly(vinyl alcohol) (PVA) blend films were modified by crosslinking through soaking the films in glutaraldehyde aqueous solution and then heating in an oven. The effects of the concentration of the glutaraldehyde aqueous solution, soaking time, reaction temperature, and time on the crosslinking reaction were investigated. The moisture absorption and mechanical properties of the films were measured to characterize the influence of the crosslinking modification. It was found that the crosslinking modification significantly reduced the moisture sensitivity of the TPS/PVA blend films and increased the tensile strength and Young's modulus but decreased the elongation at break of the TPS/PVA blend films. The described method could be used for posttreating TPS/PVA‐based products to optimize their properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012