Pornchai Rachtanapun

Effect of Carboxymethyl Cellulose Concentration on Physical Properties of Biodegradable Cassava Starch-Based Films

BackgroundCassava starch, the economically important agricultural commodity in Thailand, can readily be cast into films. However, the cassava starch film is brittle and weak, leading to inadequate mechanical properties. The properties of starch film can be improved by adding plasticizers and blending with the other biopolymers.ResultsCassava starch (5%w/v) based films plasticized with glycerol (30 g/100 g starch) were characterized with respect to the effect of carboxymethyl cellulose (CMC) concentrations (0, 10, 20, 30 and 40%w/w total solid) and relative humidity (34 and 54%RH) on the mechanical properties of the films. Additionally, intermolecular interactions were determined by Fourier transform infrared spectroscopy (FT-IR), melting temperature by differential scanning calorimetry (DSC), and morphology by scanning electron microscopy (SEM). Water solubility of the films was also determined. Increasing concentration of CMC increased tensile strength, reduced elongation at break, and decreased water solubility of the blended films. FT-IR spectra indicated intermolecular interactions between cassava starch and CMC in blended films by shifting of carboxyl (C = O) and OH groups. DSC thermograms and SEM micrographs confirmed homogeneity of cassava starch-CMC films.ConclusionThe addition of CMC to the cassava starch films increased tensile strength and reduced elongation at break of the blended films. This was ascribed to the good interaction between cassava starch and CMC. Cassava starch-CMC composite films have the potential to replace conventional packaging, and the films developed in this work are suggested to be suitable for low moisture food and pharmaceutical products.

Mechanical and Physical Properties of Cassava Starch-Gelatin Composite Films

The effect of gelatin concentrations on the mechanical properties and solubility of cassava starch-based films containing glycerol was studied. Increasing concentration of gelatin increased tensile strength but reduced elongation at break and water solubility of the composite films. Films containing 30% gelatin showed the highest tensile strength. Fourier transform infrared spectroscopy (FT-IR) spectra indicated intermolecular interactions between cassava starch and gelatin in composite films. The X-ray diffraction (XRD) technique demonstrated pseudo-crystalline regions in the cassava starch-gelatin composite films, and it is supposed that the interactions between cassava starch and gelatin were shown in the diffractograms by shifts in scattering angles. The differential scanning calorimetry (DSC) thermograms and scanning electron microscopy (SEM) micrographs confirmed homogeneity of cassava starch-gelatin films. Cassava starch-gelatin composite films have the potential to replace conventional packaging, and the films developed in this work are suggested to be suitable for low-moisture food and pharmaceutical products.

1H-NMR analysis of degree of substitution in N,O-carboxymethyl chitosans from various chitosan sources and types

N,O-Carboxymethyl chitosans were synthesized by the reaction between shrimp, crab and squid chitosans with monochloroacetic acid under basic conditions at 50°C. The mole ratio of reactants was obtained from various reaction conditions of shrimp chitosan polymer and oligomer types. The mole ratio 1:12:6 of chitosan:sodium hydroxide:monochloroacetic acid was used for preparing carboxymethyl of chitosan polymer types while carboxymethyl of chitosan oligomer types were used the mole ratio 1:6:3 of chitosan:sodium hydroxide:monochloroacetic acid. The chemical structure was analyzed by fourier transformed infrared spectroscopy (FT-IR) and proton nuclear magnatic resonance spectroscopy (1H-NMR). The FT-IR was used for confirm the insertion of carboxymethyl group on chitosan molecules. The 1H-NMR was used for determining the degree of substitution (DS) of carboxymethylation at hydroxyl and amino sites of chitosans. Carboxymethyl chitosan samples had the total DS of carboxymethylation ranging from 1.0-2.2. The highest of DS of carboxymethylation was from shrimp chitosan oligomer type.

Effect of Molecular Sizes, Sources of Chitosan and Plasticizer Types on Properties of Carboxymethyl Chitosan Films

Carboxymethyl chitosan (CMCH) from two molecular sizes (oligomer and polymer) and three different sources (shrimp, crab and squid) of chitosan were prepared by carboxymethylation reaction. The CMCH films were cast and their mechanical properties. For molecular sizes, the polymer CMCH films showed higher %elongation (%E) than those of oligomer CMCH films but had no effect on tensile strength (TS). The crab polymer CMCH films showed the highest TS. The different sources of chitosan had no influence on %E of CMCH films. The effect of plasticizers [glycerol (Gly), sorbitol (Sor) and polyethylene glycol 400 (PEG)] on mechanical properties of CMCH films was also investigated. Additions of Gly and Sor into films increased %E and reduced TS of CMCH films; however, films plasticizing with PEG showed no significant difference in mechanical properties. The crab CMCH films were selected to determine water vapor transmission rate (WVTR) at 25°C and 65%RH. The crab oligomer CMCH films showed higher WVTR than those of crab polymer CMCH films. Addition of Sor as plasticizer decreased WVTR of crab polymer and oligomer CMCH films whereas WVTR of films with Gly depended on molecular sizes of chitosan. Addition of PEG had no effect on WVTR of CMCH films.

Characterization of microcellular foamed polyolefin blend composites with wood fiber

The effects of wood fiber content on the void fraction, cell morphology, and notched Izod impact strength of microcellular foamed HDPE/PP blend composites with wood fiber were studied. The influence of wood fiber content on the carbon dioxide adsorption and desorption in the samples was also examined. Adsorption of carbon dioxide decreased with increased wood fiber content. Gas diffusion rates were faster as wood fiber content increased. The void fraction decreased dramatically when wood fiber was introduced in the blend. Environmental scanning electron microscopy (ESEM) was used to investigate the effects of wood fiber content on cell morphology. The 30:70 HDPE/PP polymer blend without wood fiber resulted in a high void fraction, with a uniform and well-developed microcellular structure, but when wood fiber was introduced, a uniform and well-developed microcellular structure could not be produced. The effects of foaming on Izod impact strength were dependent on wood fiber content.

Correlation of density and properties of particleboard from coffee waste with urea–formaldehyde and polymeric methylene diphenyl diisocyanates

The effect of urea–formaldehyde adhesive and polymeric methylene diphenyl diisocyanates adhesive on the manufacture of particleboard using coffee waste as a raw material was investigated. The coffee waste was blended with the urea–formaldehyde or polymeric methylene diphenyl diisocyanates, then hot-pressed at 140°C at two pressure levels. The particleboards were tested to certify their density, moisture content, thickness swelling, water absorption, bending strength and modulus of elasticity. The density, moisture content and bending strength of the sample increased, but thickness swelling and water absorption decreased with increasing quantity of the urea–formaldehyde and polymeric methylene diphenyl diisocyanates. The particleboard with urea–formaldehyde and polymeric methylene diphenyl diisocyanates at the same quantity, the density, moisture content, thickness swelling, water absorption, bending strength and modulus of elasticity of polymeric methylene diphenyl diisocyanates were better than urea–formaldehyde adhesive. At the same adhesive content, the urea–formaldehyde adhesive samples above 18% urea–formaldehyde content and all of the samples with PMDI adhesive met the Thai industrial standards.

Study of Carboxymethyl Cellulose from Papaya Peels as Binder in Ceramics

Effects of carboxymethyl cellulose from papaya peel (CMCp) on the properties of ceramics were investigated. Cellulose was extracted from papaya peels by NaOH and then it was modified by chloro acetic acid to obtain carboxymethyl cellulose. The prepared CMCp was applied as a binder in ceramic slip in order to increase its viscosity. Sodium silicate was also added into the slip for providing a dispersion of slip and protecting the sedimentation of clay particles. Various concentrations of CMCp and commercial CMC (CMCc) (0.05, 0.1, 0.15, 0.2 and 0.25% w/w of dry weight of clays) were added into the slip. Effect of CMC on viscosity of the slip and the ceramic density were studied. The relationship between the ceramic properties such as, shrinkage, porosity, casting rate and bending strength (both green strength and fired strength), and CMC concentration was also observed. As increasing both CMCp and CMCc, viscosity increased while density decreased. The prepared ceramics (green ware and fired ware) added with CMCp were found to have higher strength and lower in %shrinkage than that of adding with CMCc. The thickness of the ceramic wall adding CMCc increased with increasing CMCc concentration, and time in contrast to that of CMCp as the thickness decreased with increasing CMCp concentration. However, the ceramics with addition of CMCp possessed higher strength than that of the commercial one.

Predictive mathematical modeling for EC50 calculation of antioxidant activity and antibacterial ability of Thai bee products

Antioxidant activities of bee products from Thailand (honey, bee pollen and propolis) via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulphonate) (ABTS) assays were determined. The prediction of the EC50 (the half maximal effective concentration) were studied using the logistic, sigmoidal, dose response, and asymmetric 5 parameters (5P) regression models. The antimicrobial ability was tested against Staphylococcus aureus (TISTR 517), Bacillus cereus (TISTR 687), and Escherichia coli (TISTR 1261). Propolis extract with higher total phenolic content (TPC) exhibited more effective antiradical action against the DPPH and ABTS, followed by bee pollen extract and honey. All four regression models could be used to estimate the EC50 of the bee products. However, the dose-respond and 5P provide the better EC50 prediction for the bee products than the others based on the comparability of their results to those of right-angled triangle method. Thai bee products had effective antimicrobial activities on each test microorganism. The antimicrobial potency of the bee products was ranged in the order: propolis > bee pollen > honey. Results revealed that antioxidant activity and antimicrobial ability of the bee products correlated with the TPC values.

Investigation and modeling of moisture sorption behaviour of rice starch/carboxymethyl chitosan blend films

The biopolymer films from rice starch (RS) and carboxymethyl chitosan (CMCh) were developed by solution casting. The effect of the ratios of rice starch to CMCh (100:0, 88:12, 67:33, 50:50, 33:67, 12:88 and 0:100) on water barrier properties and moisture sorption isotherm of blend films was studied. Water vapor permeability of rice starch film and CMCh film were 4.8 and 9.1 g.mm/m2.mHg.day, respectively, while those of the RS/CMCh blend films ranged between 5.0 and 9.1 g.mm/m2.mHg.day. The sorption isotherm of RS/CMCh blend films was determined at 25°C. The sorption behaviour of RS/CMCh blend films could be categorized as type II and type III isotherms. The highest equilibrium moisture content (63.5 g water/100 g dry solid) was obtained in the CMCh film at aw of 0.87. For further application of sorption isotherm data, the moisture sorption characteristic of the films can be predicted using empirical models. Lewicki, Peleg, Guggenheim-Anderson-deBoer (GAB), Brunauer-Emmett-Teller (BET), and Oswin models were tested to fit the experimental data. The Peleg equation showed the best fit to the experimental data of the RS/CMCh blend films with r2 ~ 0.997 and the lowest % RMS of 6.2-44.3.

Preparation of polycaprolactone/ethanolic extract propolis nanofibers films

Recent years, propolis has plenty of biological and pharmacological properties and its mechanisms of action have been widely investigated. There is a substantive database on the biological activity and toxicity of propolis indicating it may have many antibiotic, antifungal, antiviral and antitumor properties, among other attributes. The one-step incorporation of propolis into nanofibrous mats of polycaprolactone (PCL) by electrospinning was demonstrated. In this research, the preparation of the PCL nanofibers films added ethanolic extract propolis (EEP) by electrospinning technique was studied. The EEP content was varied from 0, 2, 4, 6, 8 and 10%. The morphology was observed by a scanning electron microscope (SEM). The functional group was investigated by FT-IR