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     

Development of chitosan/Spirulina bio‐blend films and its biosorption potential for dyes

Chitosan/Spirulina bio‐blends (CSBB) in films form were developed to be an alternative/renewable biosorbent, able to remove anionic and cationic dyes from aqueous solutions. CSBB potential as biosorbent was investigated for cationic dye Methylene Blue (MB), and anionic dyes Tartrazine Yellow (TY) and Reactive Black 5 (RB5). Chitosan and Spirulina samples were obtained and characterized, and CSBB films were prepared with different chitosan/Spirulina ratios. The CSBB films characteristics, as, mechanical properties, thermal profile, crystallinity, functional groups, morphology, and biosorption potential were strongly dependent of chitosan/Spirulina ratio. CSBB films preserved its mechanical structures at pH from 4.0 to 8.0. The biosorption capacities were 120, 110, and 100 mg g^?1 for RB5, TY, and MB, respectively. The increase of chitosan amount favored the TY and RB5 biosorption; however, the increase of Spirulina amount favored the MB biosorption. Thus, the CSBB in film form is a renewable biosorbent suitable to remove anionic and cationic dyes from aqueous solutions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44580.     

Encapsulation of cinnamaldehyde into nanostructured chitosan films

Recently, bioactive chitosan films featuring naturally derived essential oils have attracted much attention due to their intrinsic antimicrobial properties and applicability to a broad range of applications. Previously, the ability to form thick (t > 100 µm), chitosan‐essential oil films via solution casting has been demonstrated. However, the fabrication of well characterized ultrathin films (t < 200 nm) that contain essential oils remain unreported. Here, we systematically investigate increasing the incorporation of an essential oil, cinnamaldehyde (CIN) into ultrathin chitosan films. Films with and without the surfactant Span^®80 were spin‐coated. Qualitatively, films exhibited well‐defined structural color, which quantitatively ranged from 145 to 345 nm thick. Release studies confirmed that a 6× higher release of CIN was enabled by Span^®80 versus the chitosan control films, 30 µg versus 5 µg, respectively. These results suggest that nanostructured chitosan‐CIN coatings hold potential to delay bacterial colonization on a range of surfaces, from indwelling medical device to food processing surfaces. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41739.     

Optimization of the properties of chitosan lactate/hyaluronan film

Polyelectrolyte complexes represent attractive class of polymer‐based materials, finding an irreplaceable role in biomaterial preparation for tissue engineering or drug delivery beads. Mechanical properties, physical properties, and enzymatic degradation of the film prepared from chitosan lactate/hyaluronan polyelectrolyte complex, crosslinked with starch dialdehyde derivatives, were studied to optimize its composition. This work represents an example demonstrating how a minor modification of the modified complex composition changes final properties of the prepared film and emphasizes enormous variations in complex formation by crosslinking. To obtain sufficiently useful information, experimental design was employed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1413–1419, 2006     

Blended films containing polybutyrolactam and chitosan for potential wound dressing applications

In this study, polybutyrolactam (PBA) was synthesized, and the PBA/chitosan (CS) blended films were fabricated for wound dressings. The results showed that the surface roughness of the blended films decreased with the increasing ratios of CS. In addition, the tensile strength of the film with 50 wt % CS (NC50) was about 33.6 MPa and the highest compared with other films. The hydrophilicity of the blended films gradually decreased while the water vapor transmission rates (WVTRs) increased with the increase of CS content. Moreover, the blended films could be biodegradable in phosphate buffer saline. Both PBA and blended films were non‐toxic and good for L929 cells growth, showing good cytocompatibility. Furthermore, the NC50 was found to promote the cell proliferation better than other groups. It can be suggested that the NC50 combined the advantages of both PBA and CS well. Therefore, the NC50 with good cytocompatibility, mechanical properties, and WVTRs might be suitable for wound dressing applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46511.     

Glycerol‐plasticized spirulina–poly(vinyl alcohol) films with improved mechanical performance

Spirulina–poly(vinyl alcohol) (PVA)–glycerol (SPG) films with improved mechanical performance, especially tensile strength (TS) and the elongation at break (EAB), are fabricated by a casting method. The integrity, color, solubility, microstructure, thermal properties, tensile strength, and compatibility of the SPG films are assessed. SPG films became smooth, homogeneous, and flexible after plasticizing with glycerol. The presence of PVA and hydrogen bonding of PVA with glycerol and spirulina protein improves the water resistance of SPG films by decreasing water absorption of spirulina protein and decreasing water diffusion through the films. The amount of carbonaceous residues decreases from 31% to 14% because of the co‐pyrolysis of spirulina, PVA, and glycerol. TS increases from 2.5 to 26 Mpa and modulus from 53 to 610 Mpa with increasing PVA content. Glycerol enhances film flexibility and EAB up to 50%. Spirulina can be composited with hydrophilic polymers to fabricate compatible, processable and thermally recyclable films with desirable mechanical performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44842.     

Heat‐sealing properties of soy protein isolate/poly(vinyl alcohol) blend films: Effect of the heat‐sealing temperature

To promote the heat‐sealing properties of soy protein isolate (SPI) films applied in the packaging field, we mixed a synthetic polymer of poly(vinyl alcohol) (PVA) with SPI to fabricate blend films by a solution‐casting method in this study. To clarify the relationship between the heat‐sealing properties and the heat‐sealing temperature, strength, melting process, crystalline structure, and microstructure, variations of the heat‐sealing parts of the films were evaluated by means of differential scanning calorimetry, tensile testing, scanning electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy, respectively. The test results showed that both the PVA and glycerol contents greatly affected the melting behavior and heat of fusion of the SPI/PVA blends; these blend films had a higher melting temperature than the pure SPI films. The peel strength and tensile strength tests indicated that the long molecular chain of PVA had a main function of enhancing the mechanical properties above the melting temperature. With increasing heat‐sealing temperature, all of the mechanical properties were affected by the microstructure of the interface between the laminated films including the chain entanglement, crystallization, and recrystallization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Humidity regulation by stretched PP and PLA films with dispersed CaCl2

Polymer materials that regulate the relative humidity in their environment are relevant for applications in the packaging and building sectors. By integration of salts in polymer structures, such materials are able to absorb and desorb high amounts of water vapor. In this study, films of polylactic acid and polypropylene with dispersed calcium chloride (2 and 4 wt %) were produced and biaxially stretched to induce the formation of cavities. The resulting cavities in these films account up to 10 vol % and are able to contain emerging calcium chloride solution formed by water vapor absorption. These films absorb reversibly up to 15 wt % water vapor at 75% relative humidity at 23 °C. This absorption behavior is described by effective diffusion and effective sorption coefficients. Using a simple model, the effective water vapor diffusion coefficient of these films can be estimated from the permeation coefficient of the polymer and the sorption coefficient of the absorber. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45713.     

Effect of blend composition and structure on biodegradation of starch/ecoflex‐filled polyethylene films

A method to blend starches and polyethylene, and thus improve the environmental footprint, was investigated. Unlike traditional methods that utilize compatibilizers or rely on reactive extrusion to achieve the desired material compatibility, a high amylose starch, such as Gelose 80, was mixed with native starch, converted to thermoplastic starch, and compounded with Ecoflex and polyethylene. Films showed good integrity and were evaluated for mechanical properties, anaerobic biodegradability, and structure changes both before and after anaerobic sludge digestion. Mechanical properties were sufficient that these films might be utilized in a number of applications but were not recommended as a sustainable solution. Biodegradation was below the theoretical maximum, was not a linear function of the amount of biodegradable materials incorporated in the films, and was depressed further as the proportion of polyethylene increased due to an encapsulation effect. Structural evaluation showed the components of the blends remained as separate phases and the structure of the Gelose 80 was reminiscent of interphase material. Biodegradation yield appeared to be principally driven by connectivity of the starches within the films to the anaerobic sludge digestion environment. Recommendations for additional studies were given. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical and barrier properties of edible starch–protein‐based films

The present investigation dealt with the mechanical properties, water‐vapor transmission behavior at different relative humidity conditions, and DSC thermograms of edible films formulated using various proteins (casein, gelatin, albumin) in combination with starch and nonthermal as well as intense thermal blending. Nonthermal blended film showed in the DSC thermogram a double T_g, indicating poor miscibility of the components and, hence, a poor film‐forming property. However, the DSC thermogram of all the films based on intense thermal blending showed a single T_g, indicating the complete molecular miscibility of the components. Casein‐based film showed a lower water‐vapor transmission rate, water gain at different relative humidity conditions, and higher tensile strength compared to its counterparts containing gelatin and albumin. Since the casein–starch blend gave better film properties, a blend of hydrophobic carnauba wax and casein was prepared to compare the properties of hydrophilic–hydrophilic and hydrophobic–hydrophilic blends. Both these blends compared well with respect to the water‐vapor transmission rate. Wax‐based film showed multiphased behavior in the DSC thermograms and the percent elongation was lower as compared to the casein–starch blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 64–71, 2003     

Oxidized pea starch/chitosan composite films: Structural characterization and properties

In this article, a series of oxidized pea starch/chitosan (OPS/CS) blend films were prepared by a casting and solvent evaporation method. The structure, thermal behavior, and mechanical properties of the films were investigated by means of Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and tensile testing. The results suggested that, in addition to hydrogen bonding, the interactions between OPS and CS molecules were enhanced by the formation of electrostatic interaction between the negatively charged carboxyl groups on OPS and the positively charged amino groups on CS. Compared with the pea starch/chitosan (PS/CS) blend films, OPS/CS blend films exhibited significantly higher tensile strength with significantly lower elongation at break. Moreover, incorporation of CS into the OPS matrix also led to a decrease in moisture uptake by the composite film. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development and characterization of chitosan bionanocomposites containing oxidized cellulose nanocrystals

In this research, cellulose nanocrystals (CNs) were extracted from corn cobs by 2,2,6,6,‐tetramethylpiperidine‐1‐oxyl radical‐mediated oxidation combined with ultrasonic treatment for the first time. These CNs were then used as a mechanical reinforcement agent and barrier in chitosan‐based bionanocomposite films. Birefringence analyses under crossed polarizers indicated the presence of isolated nanocrystals in suspension, which was later confirmed by TEM analysis. The crystallinity index obtained from X‐ray diffraction was 92.4%. The incorporation of these nanoparticles into a filmogenic matrix of chitosan made it possible to obtain bionanocomposite films with improved properties. The water‐vapor permeability was reduced by 70%, whereas the tensile strength and Young's modulus increased by up to 136 and 224% respectively. The developed films were applied as interleaving of sliced cheese, and the efficiency was assessed by investigation of adhesion between the surfaces and by comparing its properties with two commercial interleaving products (polyethylene (PE), and Greasepel paper (GP)). Concluding, the developed films showed a substantial potential to be exploited as an interleaving film, owing to its excellent mechanical properties, permeability, hydrophobicity, and low surface adhesion compared to pure chitosan, PE, and GP films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43033.     

Influence of microwave heating time on the structure and properties of chitosan films

The aim of this study was to investigate chitosan film behavior during microwave heating for 10 different heating times from 0 to 40 min. Chitosan films were produced by casting. Their structure and properties were investigated with several techniques, including Fourier transform infrared spectroscopy and differential scanning calorimetry, but also by the measurement of the film color and the mechanical properties or by the study of the rheological properties of the rehydrated films. An original technique of gas chromatography (electronic nose) was used to analyze the film odor and highlight the presence of volatile compounds related to the Maillard reaction occurring during film heating. The results show that structural modifications occurred in two steps; this affected the polymer structure, such as the crystallization and chain scission. The appearance of the neoformed compounds was also observed and must be controlled to guarantee the safety of this food‐contact packaging material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40779.     

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.     

Functionality of chitosan-halloysite nanocomposite films for sustained delivery of antibiotics: The effect of chitosan molar mass

This study was designed to investigate functionality of tetracycline-loaded chitosan-halloysite nanocomposite films, with focus on evaluating the influence of chitosan molar mass on films applicability for sustained local antibiotic delivery. The films were prepared by casting and solvent evaporation using low, medium, and high molar mass chitosan. SEM analysis revealed compact, nonporous and rough surface of the nanocomposite films due to the presence of halloysite agglomerates and tetracycline crystals. Increasing chitosan molar mass led to higher values of elongation at break (from 21.65 ± 2.65 to 34.48 ± 2.34%), tensile strength (from 134.8 ± 13.21 to 246.36 ± 14.69 MPa), and elastic modulus (from 633.79 ± 128.37 to 716.55 ± 60.76 MPa) of the nanocomposite films. FT-IR, XRPD, and thermal analyses confirmed molar mass dependent chitosan-halloysite interactions and improved thermal stability of the nanocomposite films in comparison with chitosan films. The nanocomposite films released tetracycline in a sustained manner, with the slowest release achieved from the films consisting of low molar mass chitosan. Chitosan molar mass was confirmed to be a functionality-related characteristic of chitosan-halloysite nanocomposite films as potential sustained-release carriers for topical delivery of antibiotics. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48406.     

聚乙二醇改性壳聚糖薄膜结构与性质的研究

将壳聚糖与聚乙二醇进行共混,利用溶剂挥发成膜法制备了壳聚糖/聚乙二醇二元共混薄膜。通过红外光谱、偏光显微镜、AFM等研究了共混膜的表面形貌、微结构及力学性能。结果表明:聚乙二醇可明显改善壳聚糖薄膜的脆性,当w(PEO)≤20%时,共混物各组分间有较好的相容性。偏光显微镜照片显示共混膜中聚乙二醇颗粒结晶结构随着聚乙二醇量的增加变得更为完整。     

Synthesis and investigation of desalinating,antibacterial, and mechanical properties of tetraethylorthosilicate crosslinked chitosan/polyethylene glycol (PEG-300) membranes for reverse osmosis

Solution casting method was used to synthesize chitosan (CS)-based membranes for reverse osmosis (RO) using PEG-300 and tetraethylorthosilicate as a crosslinker. Their salt rejection (%) and permeate flux (mL/h.m²) was measured by using lab scale RO plant. FTIR spectroscopy reveals interactions between CS and PEG by shifting of  OH peak from 3237 cm⁻¹ to lower wavenumber in modified membranes. SEM results showed pores in modified membranes while pure CS membranes had uniform nonporous and dense microstructure. DMA results demonstrated that the addition of PEG lowers the T_g value up to 6.5%. Water content of membranes increases up to 82.63% as the amount of PEG increases owing to its hydrophilic nature. The bacterial killing ability showed that the modified membranes possess good antibacterial activity against Escherichia coli in comparison to the control film. The permeation results revealed that salt rejection and flux of the modified membranes increased up 60% and 86.36 mL/h.m², respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48870.     

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.     

Correlations between processing parameters,morphology, and properties of blown films of linear low‐density polyethylene/low‐density polyethylene blends. I. Crystalline biaxial orientation by IR and mechanical properties

The change of the processing parameters of a blown film operation alters the mechanical and optical properties of the films. This work studied the influence of some of these parameters on the properties of blown films made of blends of linear low‐density polyethylene (LLDPE) and LDPE. Correlations between the crystalline biaxial orientations of these films and the mechanical properties were found. The crystalline biaxial orientation was measured by IR following the Krishnaswamy approach. The a axis of the unit cell was oriented along the machine direction (MD) at all LDPE concentrations, and it was not affected by the blow‐up ratio (BUR). In contrast, the b axis changed its orientation from orthogonal to MD to along the transverse direction (TD), and it was affected by the BUR. Finally, the c axis changed its orientation from equiplanar between the MD and TD to along the thickness of the film, and it was influenced by the BUR. The decrease of the tensile mechanical properties along the MD with the increase in the amount of LDPE in the blends was attributed to the tilting of the c axis toward the film thickness. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3161–3167, 2006     

Preparation and characterization of alginate/Hydroxypropyl chitosan blend fibers

Hydroxypropyl chitosan (HPCS) was synthesized from chitosan and propylene oxide under alkali conditions. It was characterized by IR spectroscopy and X-ray diffraction (XRD). We prepared alginate/HPCS blend fibers by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCl₂ and ethanol. The structure and properties of the blend fibers were studied with the aid of IR spectroscopy, scanning electron microscopy, and XRD. The results indicate a good miscibility between alginate and HPCS because of the strong interaction of the intermolecular hydrogen bonds. The mechanical properties and water-retention properties were also measured. The best values of the tensile strength and breaking elongation of the blend fibers were obtained when the HPCS content was 30 wt %. The water-retention values of the blend fibers increased as the amount of HPCS increased. Antibacterial fibers, obtained by the treatment of the fibers with an aqueous solution of silver nitrate, exhibited good antibacterial activity to Staphylococcus aureus. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012