Blend films from konjac glucomannan and sodium alginate solutions and their preservative effect

In order to enhance the mechanical properties of konjac glucomannan film in the dry state and research the application of konjac glucomannan on food preservation domain, blend transparent film was prepared by blending 3 wt % sodium alginate aqueous solution with 4.5 wt % konjac glucomannan aqueous solution and dried at 40^oC for 4 h. The structure and properties of the blend films were studied by infrared, wide angle X‐ray diffraction, scanning electron microscopy, and differential thermal analysis. Crystallinities of blend films were increased with the increase of sodium alginate. The tensile strength and breaking elongation of the blend films in dry state were obviously higher than those of both sodium alginate and konjac glucomannan films. Tensile strength of the dry blend film achieved 77.8 MP_a when the retention of sodium alginate in the film was 27.9 wt %. The structure analysis indicated that there was a strong interaction between konjac glucomannan and sodium alginate, and this is resulted from the intermolecular hydrogen bonds. Moisture content and degree of water swelling of the blend films were increased due to the introduction of sodium alginate. Results from the film coating preservation experiment to litchi and honey peach showed that this blend film had water‐holding ability. The fruit weight loss rate and rot rate both decreased by various values. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 617–626, 2000     

Improvement of physical properties of crosslinked alginate and carboxymethyl konjac glucomannan blend films

Blend films from carboxymethyl konjac glucomannan and sodium alginate in different ratios were prepared by blending 4 wt % sodium alginate aqueous solution with 2 wt % konjac glucomannan aqueous solution. After crosslinking with 5 wt % calcium chloride aqueous solution, the blend films formed a structure of semi‐interpenetrating networks. The structure and physical properties of both uncrosslinked and crosslinked films were characterized by Fourier transformed infrared spectra (FTIR), differential thermal analysis (DTA), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests. The results indicated that the mechanical properties and the thermal stability of the films were improved by blending sodium alginate with carboxymethyl konjac glucomannan due to the intermolecular hydrogen bonds between sodium alginate and carboxymethyl konjac glucomannan. The crosslinked blend films with Ca²⁺, compared with uncrosslinked blend films, exhibited further improved physical properties due to the formation of a semi‐IPN structure. Furthermore, the degree of swelling of the crosslinked films was also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2554–2560, 2002     

Characterization of konjac glucomannan–gelatin blend films

Novel blend films of konjac glucomannan (KGM) with gelatin were prepared by using the solvent‐casting technique. Transparent blend films were obtained in all blending ratios of the two polymers. The structure and physical properties of the films were investigated by Fourier transform IR, wide angle X‐ray diffraction, thermogravimetric analysis, differential thermal analysis, scanning electron microscopy (SEM), and strength tests. The results indicated that intermolecular interactions between the KGM and gelatin occurred that were caused by hydrogen bonding and the physical properties of the films largely depended on the blending ratio. The crystallinities of the blend films decreased with the increase of the KGM. The thermal stability and mechanical properties (tensile strength and elongation at break) of the films were improved by blending KGM with gelatin. It is worth noting that the blend films had a good tensile strength of 38 MPa when the KGM content in the blend films was around 30 wt %. The surface morphology of the blend films observed by SEM displayed a certain level of miscibility. Furthermore, the water absorbability of the blend films was also measured and discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1596–1602, 2001     

Preparation and characterization of konjac glucomannan and sodium carboxymethylcellulose blend films

The novel blend films of konjac glucomannan (KGM) and sodium carboxymethylcellulose (NaCMC) were prepared by casting the mixed polymer aqueous solutions. The physical properties of the blend films from konjac glucomannan and sodium carboxymethylcellulose were investigated by using FT‐infrared (FTIR), wide‐angle X‐ray diffraction (WAXD), differential thermal analysis (DTA), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and measurements of mechanical properties. The experimental results showed that the occurrence of the interactions between KGM and NaCMC molecular chains through hydrogen bond formation, and the physical properties of the films largely depend on the blending ratio. The thermal stability, mechanical properties of both tensile strength, and elongation at break of the blend films were improved by blending KGM with NaCMC. The surface morphology of the films observed by SEM was consistent with the results mentioned above. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 26–31, 2001     

Preparation and characterization of soy protein isolate–carboxymethylated konjac glucomannan blend films

To improve the mechanical and water vapor barrier properties of soy protein films, the transparent films were prepared by blending 5 wt % soy protein isolate (SPI) alkaline water solution with 2 wt % carboxymethylated konjac glucomannan (CMKGM) aqueous solution and drying at 30 °C. The structure and properties of the blend films were studied by infrared spectroscopy, wide‐angle X‐ray diffraction spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, and measurements of mechanical properties and water vapor transmission. The results demonstrated a strong interaction and good miscibility between SPI and CMKGM due to intermolecular hydrogen bonding. The thermostability and mechanical and water vapor barrier properties of blend films were greatly enhanced due to the strong intermolecular hydrogen bonding between SPI and CMKGM. The tensile strength and breaking elongation of blend films increased with the increase of CMKGM content: the maximum values achieved were 54.6 MPa and 37%, respectively, when the CMKGM content was 70 wt %. The water vapor transmission of blend films decreased with the increase of CMKGM content: the lowest value achieved was 74.8 mg · cm^?2 · d^?1 when the CMKGM content was 70 wt %. The SPI–CMKGM blend films provide promising applications to fresh food packaging. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1095–1099, 2003     

Characterization of poly(vinylpyrrolidone)–konjac glucomannan blend films

Blend films of konjac glucomannan (KGM) and poly(vinylpyrrolidone) (PVP) were prepared by using a conventional solvent‐casting technique and dried at room temperature. The structure and physical properties were studied by infrared spectroscopy (IR), wide‐angle X‐ray diffraction (WAXD), thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscope (SEM), and by measurement of mechanical properties. The changes of carbonyl stretching bands of KGM and PVP and hydroxyl stretching region of KGM were detected by FTIR analysis. WAXD analysis revealed that the film KP‐2 got the lowest crystallinity of all the films. The tensile strength and breaking elongation of the blend films reaches the maximum value at 10 wt % PVP content. The DTA curves indicated the existence of interaction between two kinds of macromolecules. Higher thermal stability was attained by konjac glucomannan through blending with PVP. These improvements are attributable to the existence of a certain degree of interaction between KGM and PVP molecules resulted from intermolecular hydrogen bonds. Air surface morphology of the films observed by SEM was consistent with the results mentioned above. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1049–1055, 2001     

Preparation and physical properties of konjac glucomannan–polyacrylamide blend films

The blend films of konjac glucomannan (KGM) and polyacrylamide (PAAm) were prepared by using the solvent‐casting technique. Transparent blend films were obtained in all blending ratios. The physical properties of the films were investigated by Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and by measurement of mechanical properties. The results indicated the occurrence of intra‐ and intermolecular interactions of the pure components, as well as the intermolecular interactions between KGM and PAAm through hydrogen bond formation. The thermal stability and mechanical properties of both tensile strength and elongation at break of the films were improved by blending KGM with PAAm. It was worth noting that the blend film had the greatest tensile strength when the KGM content in the blend films was around 30 wt %. Surface morphology of the films observed by SEM was consistent with the above‐noted results. Furthermore, the water absorbability of the blend films was also investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 882–888, 2001     

葡甘聚糖-壳聚糖-聚乙烯醇共混膜的结构表征及性能研究

用溶液共混法制备了葡甘聚糖-壳聚糖-聚乙烯醇共混膜,并用红外光谱(FTIR)、X-射线衍射(XRD)、扫描电镜(SEM)及透光率表征了膜的结构,同时测定了共混膜的力学性能、吸水率、水蒸气透过率。结果表明:共混膜中葡甘聚糖、壳聚糖及聚乙烯醇之间存在着强烈的相互作用和良好的相容性,三者共混明显改善了纯聚合物和二元膜的性能。     

Characterization of films from chitosan and quaternized poly(4‐vinyl‐N‐butyl) pyridine solutions

All Blend films were prepared from a mixture of 2 wt % chitosan in acetate solution and 4 wt % quaternized poly(4‐vinyl‐N‐butyl) pyridine (QPVP) in aqueous solution and dried at room temperature for 72 h to obtain the films. Their structure and properties were studied by infrared (IR), wide‐angle X‐ray diffraction (WXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Crystallinities of the blend films decreased with the increase of QPVP when weight of QPVP content was less than 15.0 wt %. The thermostability, tensile strength, and breaking elongation of the films in dry state were better than those of chitosan film. Tensile strength of the blend film dried at 40°C under vacuum for 24 h achieved 56.38 MPa when the weight ratio of chitosan to QPVP was 9 : 1. The structural analysis indicated that there was a strong interaction between chitosan and QPVP resulting from strong adhesion between both polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 559–566, 2004     

Characterization of konjac glucomannan–quaternized poly(4‐vinyl‐N‐butyl) pyridine blend films and their preservation effect

Novel polymer blends were prepared from a mixture of 2 wt % konjac glucomannan and 4 wt % quaternized poly(4‐vinyl‐N‐butyl) pyridine (QPVP) in aqueous solution and dried at room temperature for 72 h. Their structure and properties were studied by infrared, wide‐angle X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Thermal stability in the dry state was reduced with increasing content of QPVP. Compared with QPVP film, the tensile strength of the films was improved in the dry state. The maximum value of 12.74% tensile break elongation was reached when the content of QPVP was 30%. Structural analysis indicated that clear phase separation was observed when the content of QPVP was only 50%. Results from the filmcoating preservation experiments with lychee showed that this blend film had water‐holding ability. The fruit weight loss rate and rot rate both decreased in various degrees. The potential uses of these novel polymer films could be as preservative films. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1868–1875, 2004     

Study on properties and aggregation structures of deacetylated konjac glucomannan/chitosan hydrochloride absorbent blend gel films

A series of novel blend films of deacetylated konjac glucomannan (d‐KGM) and Chitosan hydrochloride (CHI·HCl) were prepared successfully by using the solvent‐casting technique with different blending ratios of the two polymers. The miscibility and aggregation structure of the blend films were studied by Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction and scanning electron microscopy. The results indicated that the blend system of d‐KGM and CHI·HCl had a conditional miscibility. A new crystal occurred and hydrogen‐bonding interaction was strengthened when the CHI·HCl content in the blend films was 40%. The effects of deacetylation degree of KGM, acids (the solvent Chitosan dissolved in), temperature, and the mix ratio on the swelling behavior of the blend films were also studied. The blend film KC3 (CHI·HCl content in the blend films was 30%) had not only the highest equilibrium swelling degree (26 times) but also the highest tensile strength, and it could be regarded as a potential absorbent film material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of konjac glucomannan/poly(diallydimethylammonium chloride) blend films

A novel preservative film was prepared by blending konjac glucomannan (KGM) and poly (diallydimethylammonium chloride) (PDADMAC) in aqueous system. The effects of PDADMAC content on the miscibility, morphology, thermal stability, and mechanical properties of the blend films were investigated by density determination, scanning electron microscopy (SEM), attenuated total reflection infrared spectroscopy (ATR‐IR), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile tests. The results of the density determination predicted that the blends of KGM and PDADMAC were miscible when the PDADMAC content was less than 70 wt %. Moreover, SEM and XRD confirmed the result. ATR‐IR showed that strong intermolecular hydrogen bonds interaction occurred between the negative charge groups of KGM and the quaternary ammonium groups of PDADMAC in the blends. The tensile strength and the break elongation of the blends were improved largely to 106.5 MPa and 32.04%, when the PDADMAC content was 20 wt %. The thermal stability of the blends was higher than pure KGM. Results from the film‐coating preservation experiments with lichi and grapes showed that the blend film had excellent water‐holding and preservative ability. © 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     

海藻酸-羧甲基葡甘聚糖共混膜的结构与性能研究

对魔芋葡甘聚糖进行羧甲基化改性,制得醚化度为0.54的羧甲基葡甘聚糖。再利用溶液共混法制备海藻酸钠-羧甲基葡甘聚糖共混膜,通过红外光谱、X-射线衍射、原子吸收光谱和扫描电镜对共混膜的结构进行了表征;并测定了不同配比共混膜的拉伸强度、断裂伸长率,吸水率和水蒸汽透过率,同时考察了NaCl浓度对共混膜吸水率的影响。结果表明:共混膜中海藻酸和羧甲基葡甘聚糖间具有较强的相互作用,良好的相容性。共混膜具有良好的力学性能,在生物材料领域有潜在利用价值。     

Miscibility and properties of blend materials from waterborne polyurethane and carboxymethyl konjac glucomannan

We prepared composite materials by blending waterborne polyurethane (WPU) and carboxymethyl konjac glucomannan (CMKGM) with CMKGM content from 15 to 80 wt % in an aqueous system. The structures and properties of the blend materials were characterized by FTIR, dynamic mechanical analysis, ultraviolet spectroscopy, scanning electron microscopy, wide‐angle X‐ray diffraction, thermogravimetric analysis, and tensile testing. The results indicated that the blend sheet with 80 wt % CMKGM exhibited good miscibility and higher tensile strength (89.1 MPa) than that of both WPU (3.2 MPa) and CMKGM (56.4 MPa) sheets. Moreover, with an increase of CMKGM content, the tensile strength, Young's modulus, and thermal stability increased significantly, attributed to intermolecular hydrogen bonding between CMKGM and WPU. Based on the experimental results, the blend materials have good, or a certain degree of, miscibility over the whole range of composition ratio of WPU to CMKGM. In addition, the blend materials exhibited organic solvent resistance. This work not only provided a simple method to prepare environmentally friendly materials, but also expanded the application of CMKGM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 77–83, 2004     

Preparation and characterization of chitosan/poly(vinyl alcohol) blend fibers

Chitosan and poly(vinyl alcohol) blend fibers were prepared by spinning their solution through a viscose‐type spinneret at 25°C into a coagulating bath containing aqueous NaOH and ethanol. The influence of coagulation solution composition on the spinning performance was discussed, and the intermolecular interactions of blend fibers were studied by infrared analysis (IR), X‐ray diffraction (XRD), and scanning electron micrograph (SEM) and by measurements of mechanical properties and water‐retention properties. The results demonstrated that the water‐retention properties and mechanical properties of the blend fibers increase due to the presence of PVA in the chitosan substract, and the mechanical strength of the blends is also related to PVA content and the degree of deacetylation of chitosan. The best mechanical strength values of the blend fibers, 1.82 cN/d (dry state) and 0.81 cN/d (wet state), were obtained when PVA content was 20 wt % and the degree of deacetylation of chitosan was 90.2%. The strength of the blend fibers, especially wet tenacity could be improved further by crosslinking with glutaraldehyde. The water‐retention values (WRV) of the blend fibers were between 170 and 241%, obviously higher than pure chitosan fiber (120%). The structure analysis indicated that there are strong interaction and good miscibility between chitosan and poly(vinyl alcohol) molecular resulted from intermolecular hydrogen bonds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2558–2565, 2001     

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     

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     

Blend membranes from carboxymethylated chitosan/alginate in aqueous solution

The blend membranes were satisfactorily prepared by coagulating a mixture of O‐carboxymethylated chitosan (CM‐chitosan) and alginate in aqueous solution with 5 wt % CaCl₂, and then by treating with 1 wt % HCl aqueous solution. Their structure and miscibility were characterized by scanning electron micrograph, X‐ray diffraction, infrared spectra, differential thermal analysis, and atomic absorption spectrophotometer. The results indicated that the blends were miscible, when the weight ratio of CM‐chitosan to alginate was in the range from 1 : 1 to 1 : 5. The polymers interpenetration including a Ca²⁺ crosslinked bridge occurred in the blend membrane, and leads to high separation factor for pervaporation separation of alcohol/water and low permeation. The tensile strength in the wet state (σ_b = 192 kg cm⁻² for CM‐chitosan/alginate 1 : 1) and thermostability of the blend membranes were significantly superior to that of alginic acid membrane, and cellulose/alginate blend membranes, owing to a strong electrostatic interaction caused by —NH₂ groups of CM‐chitosan with —COOH groups of algic acid. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 610–616, 2000     

Cellulose/chitin films blended in NaOH/urea aqueous solution

Regenerated cellulose/chitin blend films (RCCH) were satisfactorily prepared in 6 wt % NaOH/4 wt % urea aqueous solution by coagulating with 5 wt % CaCl₂ aqueous solution then treating with 1 wt % HCl. The structure, miscibility, and mechanical properties of the RCCH films were investigated by infrared, scanning electron microscopy, ultraviolet spectroscopies, X‐ray diffraction, tensile test, and differential scanning analysis. The results indicated that the blends were miscible when the content of chitin was lower than 40 wt %. Moreover, the RCCH blend film achieved the maximum tensile strength in both dry and wet states of 89.1 and 43.7 MPa, respectively, indicating that the tensile strength and water resistivity of the RCCH film containing 10–20 wt % chitin was slightly higher than that of the RC film unblended with chitin. Structural analysis indicated that strong interaction occurred between cellulose and chitin molecules caused by intermolecular hydrogen bonding. Compared to the mechanical properties of chitin film, those of the blend films containing 10–50 wt % chitin were significantly improved. This work provided a novel way to obtain directly chitin material blended in the aqueous solution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1679–1683, 2002