A pinboard by
Nyok Ling Tai

PhD student , RMIT University


A biodegradable composites material with improved mechanical and physical properties for packaging.

Environmental and legislative pressure has driven industry to develop waterborne and biodegradable polymer composites. Hence, the interest in developing composites of polymers that are dispersible in water and are biodegradable is increasing due to their biodegradable nature and other desirable properties. Such composites are expected to facilitate the tailoring or designing of materials to meet the requirement of specific end users. This project aims to develop novel ionic functionalized polyurethane (FPU) and investigate the effect of FPU structure on starch properties. Starch are chosen as the polysaccharide component of the FPU-polysaccharide composite as they are biodegradable and biocompatible. PUs are well known for their excellent biocompatibility, mechanical properties and approved by FDA regulation for biomedical, pharmaceutical and food application.

Most of research to date in developing starch-PU composite materials has used starch as a filler material to provide reinforcement to composite. Yet, a well dispersed starch-PU composite contains up to 20 % w/w starch, above which phase separation occurs which leads to poor mechanical.

We have successful developed a flexible starch-FPU films with improved hydrophobicity and physical properties. It is possible to mix FPU with starch to enhance the performance the thermoplastic starch. This is because both FPU and starch contain hydrophilic groups (anionic/ cationic urethane and hydroxyl group). The hydrophilic groups in both starch and PU show potential miscibility which makes it possible to incorporate FPU into starch. Ionic polyurethane have reported to have improved compatible systems, due to coulombic forces between ionic PUI create more entanglements between the polymeric chains of the ionomers and the blending materials. Incorporating certain optimal concentration of FPU into starch matrix enhances the performance of the said FPU/starch composite in terms of mechanical properties (higher tensile strength and higher elongation at break) and improves hydrophobicity of the resultant starch-FPU composite films.


Introduction of 3‐(trimethylammonium chloride)‐2‐hydroxypropyls onto starch chains for improving the grafting efficiency and sizing property of starch‐g‐poly(acrylic acid)

Abstract: Acid‐converted cornstarch was subjected to a pretreatment of cationization using N‐(3‐chloro‐2‐hydroxypropyl) trimethylammonium chloride to introduce 3‐(trimethylammonium chloride)‐2‐hydroxypropyl (TMACHP) substituents onto starch chains. Then, the quaternized starch was further modified via a graft copolymerization of the starch with acrylic acid in aqueous medium using Fe2+‐H2O2 initiator. The investigation was carried out to reveal the influence of TMACHP substituents on the graft copolymerization and sizing properties. The graft copolymerization was evaluated with grafting efficiency, grafting ratio, and conversion of monomer to polymer while the sizing properties considered included paste viscosity, adhesions to fibers, film performances, mechanical properties of sized yarns, and desizability. It was found that the TMACHP substituents introduced was able to increase the grafting efficiency and ratio of the copolymerization. In addition, the quaternized starch‐g‐poly(acrylic acid) (QS‐g‐PAA) was superior to starch‐g‐poly(acrylic acid) (S‐g‐PAA) in the adhesions. The cationization was capable of toughening starch film due to significant increase in breaking elongation, work‐to‐break, and bending endurance of the film. Moreover, the mechanical properties of the yarns sized with QS‐g‐PAA were better than those with S‐g‐PAA. Furthermore, the QS‐g‐PAA was stable in paste viscosity and desizable from sized yarns. A low level of the quaternization could be adopted to improve the grafting efficiency and sizing properties.

Pub.: 22 Feb '16, Pinned: 26 Aug '17

Effect of spice‐incorporated starch edible film wrapping on shelf life of white shrimps stored at different temperatures

Abstract: White shrimps (Litopenaeus vannamei) are a major aquaculture product in the world fishery market. The main aim of this study was to investigate the effect of clove‐ and cinnamon‐assimilated starch edible films on the shelf life of white shrimps in terms of maintaining their freshness and other organoleptic properties. Physical, chemical, microbial and sensory qualities of edible film‐wrapped white shrimps were studied until they reached their limit of acceptability during storage at different temperatures (10 and 4 °C).Shrimp samples wrapped with spice‐assimilated edible films showed lower bacterial counts. Shelf life extension of edible film‐wrapped white shrimps was estimated to be 14 and 12 days for storage at 10 and 4 °C respectively. Reduced lipid oxidation and release of nitrogen base compounds were noted for edible film‐wrapped shrimp samples. Good consumer acceptance was noted for edible film‐wrapped shrimp samples through sensory evaluation.The results of this study show that spice‐fused edible films were effective in inhibiting the growth of microbial populations. Reductions in lipid oxidation and total volatile base nitrogen were also achieved through edible film wrapping of shrimps, which increased their consumer acceptance during sensory evaluation. © 2016 Society of Chemical Industry

Pub.: 26 Feb '16, Pinned: 26 Aug '17

Starch–Cellulose Ether Films: Microstructure and Water Resistance

Abstract: In this study, composite films of corn starch, methylcellulose and carboxymethylcellulose plasticized by glycerol or polyethylene glycol (PEG) were prepared and the effects of blending level as well as the plasticizer type on the microstructure, water vapor permeability (WVP), opacity and solubility properties were investigated. Scanning electron Microscopy (SEM) observations showed homogeneous matrix of glycerol plasticized films and it was taken as an indicator of structural integrity. PEG plasticized films exhibited discontinuous surface, and this was attributed to phase separation. WVP of the films was found between 1.5 × 10−11 and 13.3 × 10−11 g/s m Pa and composite films were more resistant to water than starch film. However, WVP values were significantly higher than many of the synthetic films; as a result, one of the potential applications for presented films might be utility as a hydrophilic polymer layer in active food packaging applications. Among the factors studied, the plasticizer type was the most effective factor on the opacity of the films. Besides, differences in solubility were attributed to the differences in their structural integrity.Starch films have good barrier properties to oxygen, carbon dioxide and lipids; however, they have limited mechanical properties and water vapor resistance. In the presented study, this problem is overcome by blending with cellulose ethers and water resistance is improved up to six folds. The developed films are in hydrophilic character when compared to conventional synthetic films such as PE and PP. Therefore, the developed films are quite appropriate to be used as a carrier polymer matrix for active hydrophilic and/or volatile compounds in active food packaging applications. Another potential applications of those films presented in this study is utilization as edible film layer where mechanical and permeability resistance needed.

Pub.: 22 Mar '16, Pinned: 26 Aug '17

Modification of Physicochemical and Thermal Properties of Starch Films by Incorporation of TiO2 Nanoparticles

Abstract: In this research, potato starch and TiO2 nanoparticles (0.5, 1 and 2 weight %) films were developed. Influences of different concentrations of TiO2 on the functional properties of nanocomposite films (water-related properties, mechanical characteristics, and UV transmittance) were investigated. XRD, FTIR, and DSC analyses were used to characterize the morphology and thermal properties of the films. The results revealed that TiO2 nanoparticles dramatically decreased the values of water-related properties (water vapor permeability: 11-34%; water solubility: 1.88-9.26%; moisture uptake: 2.15-11.18%). Incorporation of TiO2 led to a slight increment of contact angle and tensile strength, and a decrease in elongation at break of the films. TiO2 successfully blocked more than 90% of UV light, while opacity and white index of the films were enhanced. Glass transition temperature and melting point of the films were positively affected by the addition of TiO2 nanoparticles. The result of XRD study exhibited that due to a limited agglomeration of TiO2 nanoparticles, the mean crystal size of TiO2 increased. Formation of new hydrogen bonds between the hydroxyl groups of starch and nanoparticles was confirmed by FTIR spectroscopy. In conclusion, TiO2 nanoparticles improved the functional properties of potato starch film and extended the potential for food packaging applications.

Pub.: 28 Apr '16, Pinned: 26 Aug '17

Foods, Vol. 5, Pages 1: Water Sorption Isotherm of Pea Starch Edible Films and Prediction Models

Abstract: The moisture sorption isotherm of pea starch films prepared with various glycerol contents as plasticizer was investigated at different storage relative humidities (11%–96% RH) and at 5 ± 1, 15 ± 1, 25 ± 1 and 40 ± 1 °C by using gravimetric method. The results showed that the equilibrium moisture content of all films increased substantially above aw = 0.6. Films plasticized with glycerol, under all temperatures and RH conditions (11%–96%), adsorbed more moisture resulting in higher equilibrium moisture contents. Reduction of the temperature enhanced the equilibrium moisture content and monolayer water of the films. The obtained experimental data were fitted to different models including two-parameter equations (Oswin, Henderson, Brunauer–Emmitt–Teller (BET), Flory–Huggins, and Iglesias–Chirife), three-parameter equations Guggenhiem–Anderson–deBoer (GAB), Ferro–Fontan, and Lewicki) and a four-parameter equation (Peleg). The three-parameter Lewicki model was found to be the best-fitted model for representing the experimental data within the studied temperatures and whole range of relative humidities (11%–98%). Addition of glycerol increased the net isosteric heat of moisture sorption of pea starch film. The results provide important information with estimating of stability and functional characteristics of the films in various environments.

Pub.: 24 Dec '15, Pinned: 26 Aug '17

Effects of pH and Salts on Physical and Mechanical Properties of Pea Starch Films

Abstract: To identify the significant contribution of intermolecular hydrogen bonds of starch molecules to the film structure formation, pH of film‐forming solutions was adjusted and also various salts (NaCl, CaCl2, CaSO4, and K2SO4) were mixed into the glycerol‐plasticized pea starch film. The film made from pH 7 possessed the highest tensile strength‐at‐break (2 times) and elastic modulus (4 to 15 times) and the lowest elongation‐at‐break compared with those of the films made from acid and alkali environments. The pH 7 film also has the highest film density and the lowest total soluble matter. At the level of 0.01 to 0.1 M of CaSO4 and 0.1 M of K2SO4 in a kilogram of starch, the water solubility of the film increased, while chloride salts slightly lowered the solubility. NaCl and CaSO4 reduced water vapor permeability (WVP), while CaCl2 slightly increased WVP at 0.01 and 0.06 M concentrations, and K2SO4 significantly increased WVP at 0.03 and 0.15 M. Presence of salts increased tensile strength (5 to 14 times than the control films) and elastic modulus (35 to 180 times) of starch film at 0.01 to 0.03 M of CaSO4 and K2SO4. Elongation‐at‐break increased significantly as salt concentration increases to an optimal level. However, when the concentration exceeded above the optimal level, the E of starch films decreased and showed no significant difference from the control film. Overall, the addition of salts modified physical and mechanical properties of pea starch films more than pH adjustment without any salt addition.High amylose starch is a naturally made linear polymer and has a great potential for various polymer applications such as biodegradable plastics, edible coatings/films, a delivery matrix for flavors, nutraceuticals, and pharmaceuticals. By altering pH and including various salts, the mechanical and physical properties of the starch films were modified to be more suitable for the industrial applications. These treatments can improve the process applicability and material suitability of starch films without complicated R&D processes required cost and high technology for food and pharmaceutical industry.

Pub.: 31 May '16, Pinned: 26 Aug '17

Mechanical and Physical Properties of Pea Starch Edible Films in the Presence of Glycerol

Abstract: The mechanical properties and moisture sorption at relative humidity (RH) range of 11–94%, water vapor permeability (WVP), solubility in water and color of the pea starch films as a function of glycerol were examined. The results showed that increasing the concentration of plasticizer resulted in improvement of the tensile strength of the films at RH <43%, the percent elongation as well as the deformation at break at RH <84%. Increasing plasticizer content and RH also resulted in films with lower Young's modulus, lower puncture force, but higher puncture deformation. Furthermore, increasing plasticizer content led to the films with more opaque appearance. Films prepared with 15 and 25% glycerol had lower WVP in comparison with unplasticized film. This study provides information regarding the advantageous or disadvantageous of possible application of pea starch films in food packaging industry.Starch edible films have been utilized for packaging technologies and edible coatings. Pea starch has been found to produce the films with improved physical and mechanical properties in comparison with films prepared from other starches due to high amount of amylose. The development of pea starch film with improved functions affects its application. Pea starch edible films may find practical applications in the poultry, meat, seafood, fruit, vegetable, grains and candies industries.

Pub.: 01 May '16, Pinned: 26 Aug '17

Effect of various plasticizers and concentration on the physical, thermal, mechanical, and structural properties of cassava‐starch‐based films

Abstract: The present study investigated the effects of plasticizers (fructose, urea, tri‐ethylene glycol, and triethanolamine) with different concentrations on the physical, thermal, and mechanical properties of cassava‐starch‐based films. The film samples were prepared using casting methods. The moisture content, water solubility, and water absorption of the films increased with increasing plasticizer content. Fructose‐plasticized films show excellent water resistance compared to other plasticizers. Film plasticized with 30% fructose showed the highest density (1.74 g/cm3), but the lowest water content (10.96%) and water absorption (110%). Films containing fructose presented smooth surfaces without pores. The glass transition temperatures of the plasticized film also decreased with increased plasticizer content, irrespective of the plasticizer type. The relative crystallinity decreased with increasing plasticizer content. The film plasticized by 30% fructose presented higher relative crystallinity (0.31). The increase of plasticizer concentration resulted in a decrease of tensile strength, but increased elongation at break of the film samples. Film plasticized with 30% fructose showed the highest tensile strength (4.7 MPa) and tensile modulus (69 MPa). Thus, fructose was the most efficient plasticizer agent among the various plasticizers used in this study. High contents of plasticizer resulted in changes in the properties of the films. Overall, it can be concluded that the plasticizer type and concentration significantly influence the properties of cassava‐starch‐based film.

Pub.: 02 Jun '16, Pinned: 26 Aug '17

Starch‐based films and food coatings: An overview

Abstract: Native and modified starches have received considerable attention for biodegradable films formulation due to their completely biodegradable nature, edible characteristics, and low cost. Development and characterization of starch films obtained by: (i) casting, (ii) blown extrusion and (iii) the thermo‐compression moulding process are described. The rheological properties of filmogenic suspensions, the barrier properties, and the mechanical resistance of the obtained films are reported. Addition of specific additives to the formulations modifies the film functionality transforming them into active materials. Diffusion of antimicrobial agents such as potassium sorbate from the active starch film, as well as their efficacy in dairy products is discussed. Likewise, reinforcing agents lead to composite materials with improved mechanical resistance. Starch‐based materials show higher permeability to carbon dioxide than to oxygen, which is useful to control the respiration rate of fruits and vegetables. The application of active starch‐based coatings to strawberries and Brussels sprouts in order to prolong their refrigerated storage life is analyzed. A detailed overview on the formulation and performance of starch‐based films employing industrial and lab‐scale methods, as well as the application of starch coatings to improve food quality is presented, with the aim of analyzing the possibility of development and application of such materials.

Pub.: 19 Jun '16, Pinned: 26 Aug '17

The effect of LiCF 3 SO 3 on the complexation with potato starch-chitosan blend polymer electrolytes

Abstract: Abstract This work examines the effect of lithium trifluoromethanesulfonate (LiCF3SO3) and glycerol on the conductivity and dielectric properties of potato starch-chitosan blend-based electrolytes. The electrolytes are prepared via solution cast technique. From X-ray diffraction (XRD) analysis, the blend of 50 wt.% starch and 50 wt.% chitosan is found to be the most amorphous blend. Fourier transform infrared (FTIR) spectroscopy studies show the interaction between the electrolyte materials. The room temperature conductivity of pure starch-chitosan film is found to be (2.85 ± 1.31) × 10−10 S cm−1. The incorporation of 45 wt.% LiCF3SO3 increases the conductivity to (7.65 ± 2.27) × 10−5 S cm−1. Further conductivity enhancement up to (1.32 ± 0.35) × 10−3 S cm−1 has been observed on addition of 30 wt.% glycerol. This trend in conductivity is verified by XRD and dielectric analysis. The temperature dependence of conductivity of all electrolytes are Arrhenian.AbstractThis work examines the effect of lithium trifluoromethanesulfonate (LiCF3SO3) and glycerol on the conductivity and dielectric properties of potato starch-chitosan blend-based electrolytes. The electrolytes are prepared via solution cast technique. From X-ray diffraction (XRD) analysis, the blend of 50 wt.% starch and 50 wt.% chitosan is found to be the most amorphous blend. Fourier transform infrared (FTIR) spectroscopy studies show the interaction between the electrolyte materials. The room temperature conductivity of pure starch-chitosan film is found to be (2.85 ± 1.31) × 10−10 S cm−1. The incorporation of 45 wt.% LiCF3SO3 increases the conductivity to (7.65 ± 2.27) × 10−5 S cm−1. Further conductivity enhancement up to (1.32 ± 0.35) × 10−3 S cm−1 has been observed on addition of 30 wt.% glycerol. This trend in conductivity is verified by XRD and dielectric analysis. The temperature dependence of conductivity of all electrolytes are Arrhenian.33−10−133−5−1−3−1

Pub.: 01 Sep '16, Pinned: 26 Aug '17

Effect of biodegradable chitosan–rice-starch nanocomposite films on post-harvest quality of stored peach fruit

Abstract: A nanocomposite degradable chitosan–rice-starch (CRS) film was prepared by incorporation of commercial (Comm.) and microbial synthesized silver (Ag) and zinc oxide (ZnO) nanoparticles (NPs) using a solvent-casting technique. The prepared films were characterized for thickness, surface color measurement, transparency, presence of crystalline features, surface topography, and surface elemental composition. The fabricated nanocomposite films were evaluated for antimicrobial activity and were observed to curb the growth of test Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) microorganisms in an in vitro media Petri plate study. The screened nanocomposite films were then tested to improve the shelf life of peach fruits (cv. Shan-i-Punjab) in packaging. The nanocomposite films with incorporated NPs decreased the overall surface microbial load and enhanced the shelf life of packed peach fruits as compared to unpackaged and packaged fruits with control film. The lowest percentage loss in weight (4.75%) was recorded in peach fruits packaged with film incorporated with Comm. Ag NPs. The lowest change in diameter (4.25–4.05 cm) and the highest ascorbic acid content (0.51 mg/g) were found in peach fruits packaged with films incorporated with Comm. ZnO NPs. The lowest percent (9.6%) increase in total soluble solids was observed for fruits packaged with films incorporated with Comm. AgNPs. The microbial counts on the surface of the fruit was highest for the unpackaged control treatment and lowest for fruits packaged with Comm. Ag NPs. SEM study of the surface of the peaches showed the presence and adherence of microbial cells (bacteria, yeast, and fungi) on the trichomes and the fruit surface.

Pub.: 03 Jan '17, Pinned: 26 Aug '17