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     

Preparation and characterization of alginate/gelatin blend fibers

Alginate and gelatin blend fibers were prepared 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 infrared spectra, scanning electron micrography, X‐ray diffraction, and thermogravimetric analysis. Mechanical properties and water‐retention properties were measured. The best values of the tensile strength and breaking elongation of blend fibers were obtained when gelatin content was 30 wt %. The water‐retention values of blend fibers increase as the amount of gelatin is raised. The structural analysis indicated that there was strong interaction and good miscibility between alginate and gelatin molecules resulted from intermolecular hydrogen bonds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1625–1629, 2005     

Behavior of alginate–gelatin blended gel with embedded macrovoids: Stress-induced changes and the solute release characteristics

Blending of gelatin to alginate promote cell–material interaction. However, the changes in diffusive and mechanical properties need to be ascertained. This study shows that the presence of two superposed polymer networks, where gelatin is not additionally crosslinked resulted in higher uptake and slower release of vitamin B₁₂. In the presence of gelatin, the stress is found higher for the same level of compressive deformation, and the permeability of the pore fluid during expulsion under compressive stress is found significantly lower. Also, a large residual strain at the end of each cycle in case of cyclic compression is observed, when gelatin is present. A microfluidic device is used to introduce voids uniformly across the blended gel with an objective to increase compressibility, permeability (for faster equilibration of pore pressure), and uptake of bioactive species. The results showing lower permeability and higher uptake in the presence of gelatin are discussed.     

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     

Development of silver nanoparticles‐loaded calcium alginate beads embedded in gelatin scaffolds for use as wound dressings

Silver nanoparticles (AgNPs)‐loaded calcium alginate beads embedded in gelatin scaffolds were developed to sustain and maintain the release of silver (Ag⁺) ions over an extended time period. The UV irradiation technique was used to reduce Ag⁺ ions in alginate solution to AgNPs. The average sizes of AgNPs ranged between ca 20 and ca 22 nm. The AgNPs‐loaded calcium alginate beads were prepared by electrospraying of a sodium alginate solution containing AgNPs into calcium chloride (CaCl₂) solution. The AgNPs‐loaded calcium alginate beads were then embedded into gelatin scaffolds. The release characteristics of Ag⁺ ions from both the AgNPs‐loaded calcium alginate beads and the AgNPs‐loaded calcium alginate beads embedded in gelatin scaffolds were determined in either deionized water or phosphate buffer solution at 37 °C for 7 days. Moreover, the AgNPs‐loaded calcium alginate beads embedded in gelatin scaffolds were tested for their antibacterial activity and cytotoxicity. © 2014 Society of Chemical Industry     

Preparation of interpenetrating polymer network gel beads for dye absorption

Preparation of interpenetrating polymer network (IPN) gel beads for dye absorption was carried out by using simultaneous crosslinking method. First, sodium alginate (SA), 3‐(methacrylamido) propyl trimethyl ammonium chloride (MAPTAC), and/or acrylamide (AM), K₂S₂O₈, and N,N′‐methylenebisacrylamide (MBAM) were mixed in aqueous solution. The beads were prepared using K₂S₂O₈ and MBAM as the initiator and crosslinking agent, respectively. Then, the solution was dropped into CaCl₂ solution mixed with N,N,N′,N′‐tetramethylethylenediamine (TMEDA). The former was used as the crosslinking agent of alginate and the latter was used as the accelerator for the polymerization of monomer in the alginate solution. The gel bead composed of only alginate was also prepared to compare the properties with IPN gel bead. The components in IPN gel bead were examined by FTIR analysis. The factors effecting the particle size of alginate and IPN gel beads were investigated. In alginate gel bead, the concentration of solution affected the particle size, whereas type of monomer affected the particle size of IPN gel bead. The IPN gel bead had smooth surface (from SEM results), different from the alginate bead. Alginate content caused the swelling behavior of dried IPN beads. Cationic dye was absorbed by crosslinked alginate gel bead. The absorption of reactive dye by IPN gel bead was a result of its cationic charge. The absorption density of IPN gel beads was the reciprocal of the absorbent dosage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1585–1591, 2006     

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     

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     

海藻酸钙/纳米TiO_2共混纤维的制备与表征

将含固体质量分数为5%的海藻酸钠纺丝原液与纳米二氧化钛(TiO2)水分散液均匀混合,制得海藻酸钠/纳米TiO2混合纺丝原液,采用湿法纺丝,通过氯化钙凝固浴,经拉伸、水洗,制备了海藻酸钙/纳米TiO2共混纤维,研究了纳米TiO2含量对共混纤维结构及性能的影响。结果表明:纳米TiO2的加入,提高了共混纤维的力学性能;加入质量分数为0.5%的纳米TiO2,海藻酸钙大分子链上的红外特征吸收峰峰形明显变宽,共混纤维的力学性能最佳,断裂强度为2.93 cN/dtex,断裂伸长率为7.34%,优于海藻酸钙纤维;添加纳米TiO2质量分数为3%时,纳米TiO2在共混纤维中仍能较好的分散,且纤维表面光滑。加入纳米TiO2后,共混纤维的热稳定性提高。     

Controlled mechanical and swelling properties of poly(vinyl alcohol)/sodium alginate blend hydrogels prepared by freeze–thaw followed by Ca2+ crosslinking

Poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend hydrogels have immense potential for use as functional biomaterials. Understanding of influences of processing parameters and compositions on mechanical and swelling properties of PVA/SA blend hydrogels is very important. In this work, PVA/SA blend hydrogels with different SA contents were prepared by applying freeze–thaw method first to induce physical crosslinking of PVA chains and then followed by Ca²⁺ crosslinking SA chains to form interpenetrating networks of PVA and SA. The effects of number of freeze–thaw cycles, SA content and Ca²⁺ concentration on mechanical properties, swelling kinetics, and pH‐sensitivity of the blend hydrogels were investigated. The results showed that the blend hydrogels have porous sponge structure. Gel fraction, which is related to crosslink density of the blend hydrogels, increased with the increase of freeze–thaw cycles and strongly depended on SA content. The SA content exerts a significant effect on mechanical properties, swelling kinetics, and pH‐sensitivity of the blend hydrogels. The number of freeze–thaw cycles has marked impact on mechanical properties, but no obvious effect on the pH‐sensitivity of the PVA/SA blend hydrogels. Concentration of CaCl₂ aqueous solution also influences mechanical properties and pH‐sensitivity of the blend hydrogel. By altering composition and processing parameters such as freeze–thaw cycles and concentration of CaCl₂ aqueous solution, the mechanical properties and pH‐sensitivity of PVA/SA blend hydrogels can be tightly controlled. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Production of doxycycline‐loaded gelatin microspheres through thermal treatment in inverse suspensions

Doxycycline is a broad‐spectrum antibiotic. The development of a polymer matrix that can allow for the controlled release of this drug can bring many benefits to veterinary and human medicine. For this reason, in the present study doxycycline was encapsulated in situ with gelatin through thermal treatments performed in inverse suspension, using distinct gelatin concentrations in the suspended aqueous phase. To characterize the performances of the obtained products, controlled release tests were performed. The effect of adding formaldehyde and glucose into the reaction medium to enhance gelatin crosslinking was analyzed, although obtained results indicated that addition of crosslinking agents is not necessary because addition of doxycycline is sufficient to promote the physical gelatin crosslinking. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers     

Preparation and characterization of nano‐SiO2 reinforced alginate‐based nanocomposite films (II)

Crosslinked alginate‐based nanocomposites at different SiO₂ contents were prepared successfully by blending the nano‐SiO₂ solution into low concentration alginate solution (0.5 wt %), with the alginate concentration increased step by step to the resulted concentration, in this course glycerol was used as plasticizer and 5 wt % CaCl₂ as crosslinker. The combined effect of SiO₂ content (1.5–8 wt %) on the microstructural, physical, mechanical, and optical properties of the nanocomposite films were investigated. The results showed that tensile strength and elongation was improved by about 40.33% and 89%, respectively, upon increasing the SiO₂ content to 4.5 wt %. In addition, water vapor permeability and swelling degree decreased by 19% and 16% with increasing SiO₂ content up to 8 and 4.5 wt %, respectively with respect to pure crosslinked alginate film. Thermogravimetric analysis also revealed that nano‐SiO₂ can improve the thermal stability of sodium alginate films produced by this method. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45286.     

Structural and physical properties of silk fibroin/alginate blend sponges

Silk fibroin/alginate blend sponges were examined through IR spectroscopy, X‐ray diffractometry, and differential scanning calorimetry to determine the structural changes of silk fibroin. The effects of fibroin/alginate blend ratios on the physical and mechanical properties were investigated to discover the feasibility of using these blend sponges as biomedical materials such as wound dressings. The compressive modulus of silk fibroin was increased up to 30 kPa, from 7.1 kPa, by blending with alginate. Thermal crystallization behavior of fibroin induced by heat treatment was restricted by blending with alginate. In spite of that, the structural characteristics of fibroin were not changed by incorporation with alginate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2174–2179, 2004     

Enhancement of Solute Release From Chitosan Scaffold With Embedded Submillimeter Voids

Chitosan scaffold has potential use in the controlled release of drugs, and as 3-D structure for the formation of tissue matrix. This article describes the solute release behavior of chitosan scaffold that bears embedded voids of submillimeter dimensions. Formaldehyde and glyoxal were considered as crosslinkers, and alcohol ethoxylate was used as the surfactant. Nitrogen gas was bubbled in a fluidic arrangement to generate an ensemble of self-aligned bubbles in chitosan, prior to the crosslinking. The crosslinked gel was dried in a vacuum oven, and subsequently, the absorption capacity of the scaffold in PBS buffer was estimated. The type of crosslinker significantly affected the absorption capacity of the scaffold. The dimensions of the voids immediately after the cross-linking of gel, and also after complete drying were obtained using a digital microscope and a scanning electron microscope respectively. Two levels of porosity are evident from these images. The smaller pores were intrinsically provided by the gel matrix. The larger ones were induced by the fluidic arrangement. The porosity of the gel was measured gravimetrically. The uptake of Vitamin B-12 was found significantly higher when formaldehyde was used as crosslinker instead of glyoxal. The release of Vitamin B-12 in PBS buffer on a shaker was studied. For comparison, the experiment was repeated with a scaffold that did not have any embedded void. The enhancements in the release of Vitamin B-12 due to the presence of voids are estimated in this article. The bubbles, placed in more than one layer, enhanced the porosity and the ability to absorb Vitamin B-12 further.     

The effect of alginate on the mechanical,thermal, and rheological properties of nano calcium carbonate‐filled polylactic acid composites

Traditional plasticizers to modify polylactic acid (PLA) usually leads to limited biodegradation, due to its inherent non‐biodegradability of additives. In this work, we report a melt blending method to modify PLA using the alginic acid and two different alginates combined with nano CaCO₃, a fully sustainable and biodegradable component. And, the mechanical, thermal, and rheological properties of the composites are investigated. We demonstrated that the filled samples show a lower tensile strength and higher impact strength which means a toughening effect occurs. Dynamic mechanical analysis experiments showed that the calcium alginate‐filled samples show higher performances than other filled samples not only in static mechanical but also dynamic mechanical properties. The fracture morphology of the samples shows that a better interfacial reaction has been constituted for gel calcium alginate between CaCO₃ and PLA. Nevertheless, the thermogravimetric analysis results indicate that a lower thermal stability has been achieved in alginate filled samples. Chemorheological study indicated the alginate‐filled samples also show a lower modulus and viscosity than neat PLA. It was found that the complex viscosity decrease with the addition of alginates, in comparison with PLA/CaCO₃ composites, and the samples filled with calcium alginate show a higher viscosity than those of sodium alginate and alginic acid. The alginate derivatives showed interesting potential as new green plastic additives attributed to origin from the biodegradable natural resources with a polymeric matrix. POLYM. ENG. SCI., 59:1882–1888, 2019. © 2019 Society of Plastics Engineers     

Characterization of polyvinyl alcohol/gelatin blend hydrogel films for biomedical applications

In the present investigation, attempt was made to prepare blend hydrogel by esterification of polyvinyl alcohol with gelatin. The blend hydrogel was further converted into films by the conventional solution‐casting method. These films were characterized by FTIR, DSC, and X‐ray diffraction studies. The refractive index and viscosity of different composition of the blends were measured in the solution phase of the material. The mechanical properties of the blend films were measured by tensile test. Swelling behavior of the blend hydrogel was also studied. The FTIR spectrum of the blend film indicated complete esterification of the free carboxylic group of gelatin. The DSC results indicate that the addition of gelatin with PVA changes the thermal behavior like melting temperature of PVA, which may be due to the miscibility of PVA with gelatin. The interaction of gelatin with PVA molecule changes the crystallite parameters and the degree of crystallinity. The crystallinity of the blend film was mainly due to gelatin. The comparison of viscosity indicated an increase in the segment density within the molecular coil. The results revealed the changes observed in the properties of the gel, and it enhances the gel formation at viscoelastic phase of the material. The blend film had sufficient strength and water‐holding capacity. The results obtained indicated that the blend film could be used for various biomedical applications such as wound dressing and drug‐delivery systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Improved Green Strength and Green Machinability of ZrB2–SiC Through Gelcasting Based on a Double Gel Network

ZrB₂–SiC green ceramics were fabricated by aqueous gelcasting based on single AM‐MBAM, single Na‐alginate, and double gel network system. ZrB₂–SiC ceramics obtained by aqueous gelcasting based on AM‐MBAM and Na‐alginate double gel network had a dramatically highest green strength of 98.6 ± 5.1 MPa, which was 103% and 61% higher than that of ZrB₂–SiC ceramics based on single AM‐MBAM system and Na‐alginate system, respectively. A “scratch test” was conducted to evaluate the green machinability of as‐prepared ZrB₂–SiC ceramics. The ZrB₂–SiC ceramics based on this double gel network was found to have the best green machinability.     

Analysis of the performance of polysaccharide membranes in aqueous media as a tool to assist wound‐dressing selection

The behavior of hydrophilic matrixes in the presence of aqueous media plays a pivotal role in the selection of materials that come into contact with body fluids. Because polysaccharides have proven benefits in the treatment of skin lesions, the performance of membranes produced with chitosan combined with alginate [chitosan–alginate (Ch–A)], xanthan [chitosan–xanthan (Ch–X)], or guar gum [chitosan–guar gum (Ch–G)] after exposure to different aqueous solutions and humidity levels was analyzed with the aim of directing their applications as dressings in wounds with different exudate productions. The Ch–X membranes presented a high fluid‐uptake capacity and water‐vapor transmission rate (WVTR); this was attributed to ramifications in the xanthan structure, and the membranes were then recommended for moderately to highly exuding wounds. The Ch–G membranes showed a dense structure and presented low fluid‐uptake capacity; they were more appropriate for low‐exuding wounds or wounds in the advanced stage of cicatrization. Both the Ch–A and Ch–G membranes presented adequate mechanical properties in a wide range of relative humidity conditions and could be considered suitable for use in all body parts. However, as the Ch–A formulation showed limited WVTR, its use should be restrictedly to, at most, moderately exuding wounds. In all cases, the assessment of the wound type by a professional would be required to define the final dressing formulation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45386.     

Novel type of alginate gel‐based adsorbents for heavy metal removal

Various alginate gel‐based adsorbents were investigated for the removal of heavy metals: alginate beads, alginate capsules, and alginate gel‐coated adsorbent. Of these, alginate capsules showed the greatest Pb²⁺ uptake capacity of 1560 mg g^?1 of dry sodium alginate, and the alginate gel‐coated adsorbent, prepared simply by forming a thin alginate film on an inert matrix, achieved rapid adsorption equilibrium within 10 min. Adsorbed metals were readily removed from the alginate gel‐based adsorbents using eluents such as HNO₃ and could be reused for up to 10 adsorption–desorption cycles without marked loss of metal uptake capacity. Alginate gel‐coated adsorbents could be prepared in a dried state and have great application potential for the removal of heavy metals from contaminated water. Copyright © 2004 Society of Chemical Industry