For the past few decades, there has been a considerable research interest in the area of food packaging using biopolymer-based materials. Unfortunately, the water barrier property of biopolymer films is very poor. In this study, konjac glucomannan (KGM)-chitosan films incorporated with granular cassava starch (GST) and nanosilver were prepared and characterized by FTIR, SEM, XRD, TG, and DSC analysis. Incorporation of GST has significantly improved the physicochemical properties, especially the moisture barrier properties of KGM-chitosan films. Compared to neat KGM-chitosan films, the water solubility and swelling capacity of GST incorporated films decreased with increase in starch content. The moisture absorbability, water vapor transmission rate, as well as oxygen transmission rate also reduced significantly in GSTincorporated films. Contact angle measurements revealed improved hydrophobicity of GSTincorporated KGM-chitosan films. Incorporation of nanosilver particles further improved the thermal stability, tensile strength, and antimicrobial properties. Food-contact tests showed that the migration of silver was significantly lower than the permitted level of migrating quantity of silver (10 mg/L) into stored bread samples, which suggests that these KGM-chitosan-GST-nanosilver films would be safe to be used as food-packaging materials. Moreover, compared to conventional food-packaging films, these nanocomposite films also exhibited better antimicrobial activity.
Cassava starch (ST)‐konjac glucomannan (KGM) blend films were prepared and their thermal, rheological, mechanical, moisture sorption properties and water vapour transmission rate were determined. Response surface methodology was employed for the preparation of films using different levels of ST, KGM and glycerol. All the filmogenic solutions exhibited shear thinning behaviour. Apparent viscosity and the dynamic rheological properties of filmogenic solutions varied considerably with KGM content. Rheological analysis revealed that the blend films are more appropriate than neat ST film for controlled drug release studies and for food coating. The melting temperature and enthalpy of fusion of the blend films were lower than that of neat ST film. When compared to neat starch film, the blend films showed broader peaks in DSC patterns, which suggests that incorporation of KGM decreased the crystallinity of ST. Mechanical properties, elongation at break and tensile strength of blend films were significantly higher (112.8% and 22.5 MPa, respectively) than those of neat ST film. Due to the more hydrophilic nature of KGM when compared to ST, the WVTR and moisture absorption of blend films were greater than that of neat ST film. Though KGM is more hydrophillic in nature, blend films with higher amount of KGM (0.643g) showed comparably lower values for both WVTR and moisture absorption than other blends. The solubility of the blend films was lower than that of neat starch film which also confirmed the strong intramolecular attraction between ST and KGM.
Cassava starch (ST)-konjac glucomannan (KGM) blend films were prepared, characterized, and their suitability as matrices for the sustained release of a model drug, theophylline (Thp) was investigated. Structural studies showed that there was a good compatibility between ST and KGM and also revealed the existence of strong interaction between Thp and the polymer blend. The thermal stability of the films did not alter on blending of the two polymers. The water vapor transmission rate (WVTR) and swelling capacity of the blend films were higher than that of the neat ST, while lower than that of the neat KGM films. The drug release was related to the pH of the medium and the relative humidity (RH) under which the films were stored. The drug release data fitted well to Higuchi kinetic model and the mechanism corresponds to anomalous transport with non-Fickian kinetics corresponding to coupled diffusion/polymer relaxation. The rate of drug release was significantly (p<0.05) and positively correlated with the degree of erosion of the blend films. The study showed that the blend film with a composition, ST: 1.5 Â 10 À3 kg and KGM: 1.5 Â 10 À3 kg with 20% glycerol as plasticizer stored at a relative humidity in the range 11-53% was appropriate for the sustained release of the less water soluble drug, theophylline.
Cassava starch‐graft‐polymethacrylamide (PMAM) copolymers were synthesized by a free‐radical‐initiated polymerization reaction, and the products were tested for their efficiency as flocculants and textile sizing agents. The highest percentages of grafting and monomer conversion were 79.9 and 78.0%, respectively. The grafted starches were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction analysis, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. The average molecular weight of PMAM chains in the grafted starches ranged from 15.9 to 30.8 × 105 g/mol. The grafted starches exhibited a higher peak viscosity and paste stability in comparison to the native starch (NS). Dynamic mechanical analysis showed that grafting provided fairly shear‐stable hydrogels, and the highest storage modulus obtained was 17,900 Pa compared to 1879 Pa for NS. The flocculation studies demonstrated the superiority of starch‐g‐PMAM over cassava starch and PMAM as an efficient flocculant. The tensile strength of cotton yarns sized with the starch‐grafted copolymer was significantly higher (104 MPa) compared to that sized with NS (34 MPa). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39810.
Background: Resin-dentin bonds are less durable than enamel as they rely on organic part for mineralisation. Bond denaturation mainly takes place because of hydrolysis of polymerized resin or degradation of water-rich, resin-sparse collagen by collagenolytic endogenous matrix metalloproteinase and cysteine cathepsins. Hence, this limited stability of dentin bonding tenaciously reduces the longevity of tooth-coloured restorations. One of the strategies adopted to encounter this shortcoming is to induce biomimetic remineralisation. Aim: To assess the microtensile bond strength of resin composites to dentin following remineralisation using an experimental paste containing nano-hydroxyapatite (nHAp) and biomimetic analogues, Poly Acrylic Acid (PAA) and Sodium Tri Polyphosphate (STPP). Methodology: Nine intact freshly extracted third molar were used for this study to evaluate the microtensile bond strength after treating with three different groups; Group I with paste containing nano hydroxyapatite nHAp Group II paste containing nHAp and non-collagenous protein analogues such as (Polyacrcrylic acid and Sodium tripolyphosphate) and the control groups containing adhesive and resin composite with no additional treatment. The samples were observed over a period of 24 hours and 1 week the inter group data analysis was done using ANOVA and paired sample t test and the intra-group data analysis over period of 24 hours the post HOC Bonferroni test was used for the statistical analysis. Results: After 24 hours the group with nHAp group showed highest value for microtensile bond strength among other groups, however after one week the group with nHAp +NCP analogues(PAA+STPP) showed highest value for microtensile bond. Conclusion: The treatment with the experimental paste [nHAp+NCP] analogues (PAA+STPP)] can bring about remineralisation to improve bonding to dentin.
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