Ruhul A. Khan

Mechanical and barrier properties of nanocrystalline cellulose reinforced chitosan based nanocomposite films

Nanocrystalline cellulose (NCC) reinforced chitosan-based biodegradable films were prepared by solution casting. The NCC content in the films was varied from 1 to 10% (dry wt. basis). It was found that the tensile strength (TS) of the nanocomposite films with 5% (w/w) NCC content was optimum with an improvement of 26% compared to the control chitosan films. Incorporation of NCC also significantly improved barrier properties. Water vapor permeability (WVP) of the chitosan/NCC films was decreased by 27% for the optimum 5% (w/w) NCC content. Swelling studies revealed a decrease in water uptake of the NCC-reinforced chitosan films. Analyses of thermal properties showed no significant effect of NCC whereas X-ray diffraction studies confirmed the appearance of crystalline peaks in the nanocomposite films. Surface morphology of the films was investigated by scanning electron microscopy and it was found that NCC was dispersed homogenously into chitosan matrix.

Nanocrystalline cellulose (NCC) reinforced alginate based biodegradable nanocomposite film.

Nanocrystalline cellulose (NCC) reinforced alginate-based nanocomposite film was prepared by solution casting. The NCC content in the matrix was varied from 1 to 8% ((w/w) % dry matrix). It was found that the nanocomposite reinforced with 5 wt% NCC content exhibits the highest tensile strength which was increased by 37% compared to the control. Incorporation of NCC also significantly improved water vapor permeability (WVP) of the nanocomposite showing a 31% decrease due to 5 wt% NCC loading. Molecular interactions between alginate and NCC were supported by Fourier Transform Infrared Spectroscopy. The X-ray diffraction studies also confirmed the appearance of crystalline peaks due to the presence of NCC inside the films. Thermal stability of alginate-based nanocomposite films was improved after incorporation of NCC.

Production and Properties of Nanocellulose-Reinforced Methylcellulose-Based Biodegradable Films

Methylcellulose (MC)-based films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol, and 0.025% Tween 80. Puncture strength (PS), puncture deformation (PD), viscoelasticity coefficient, and water vapor permeability (WVP) were found to be 147 N/mm, 3.46 mm, 41%, and 6.34 g.mm/m(2).day.kPa, respectively. Aqueous nanocellulose (NC) solution (0.1-1%) was incorporated into the MC-based formulation, and it was found that PS was improved (117%) and WVP was decreased (26%) significantly. Films containing 0.25% NC were found to be the optimum. Then films were exposed to gamma radiation (0.5-50 kGy), and it was revealed that mechanical properties of the films were slightly decreased after irradiation, whereas barrier properties were further improved with a decrease of WVP to 28.8% at 50 kGy. Molecular interactions due to incorporation of NC were supported by FTIR spectroscopy. Thermal properties of the NC-containing films were improved, confirmed by TGA and DSC. Crystalline peaks appeared due to NC addition, found by XRD. Micrographs of films containing NC were investigated by SEM.

Nanocellulose-based composites and bioactive agents for food packaging

Global environmental concern, regarding the use of petroleum-based packaging materials, is encouraging researchers and industries in the search for packaging materials from natural biopolymers. Bioactive packaging is gaining more and more interest not only due to its environment friendly nature but also due to its potential to improve food quality and safety during packaging. Some of the shortcomings of biopolymers, such as weak mechanical and barrier properties can be significantly enhanced by the use of nanomaterials such as nanocellulose (NC). The use of NC can extend the food shelf life and can also improve the food quality as they can serve as carriers of some active substances, such as antioxidants and antimicrobials. The NC fiber-based composites have great potential in the preparation of cheap, lightweight, and very strong nanocomposites for food packaging. This review highlights the potential use and application of NC fiber-based nanocomposites and also the incorporation of bioactive agents in food packaging.

Encapsulation of probiotic bacteria in biopolymeric system.

Encapsulation of probiotic bacteria is generally used to enhance the viability during processing, and also for the target delivery in gastrointestinal tract. Probiotics are used with the fermented dairy products, pharmaceutical products, and health supplements. They play a great role in maintaining human health. The survival of these bacteria in the human gastrointestinal system is questionable. In order to protect the viability of the probiotic bacteria, several types of biopolymers such as alginate, chitosan, gelatin, whey protein isolate, cellulose derivatives are used for encapsulation and several methods of encapsulation such as spray drying, extrusion, emulsion have been reported. This review focuses on the method of encapsulation and the use of different biopolymeric system for encapsulation of probiotics.

Comparative Studies of Mechanical and Interfacial Properties Between Jute and E-glass Fiber-reinforced Polypropylene Composites

Jute fiber (hessian cloth)-reinforced polypropylene matrix composites (50 wt% fiber) were fabricated by compression molding. Tensile strength, tensile modulus, bending strength, bending modulus, and impact strength of the composites were found to be 48 MPa, 2.5 GPa, 56 MPa, 4.5 GPa, and 18 kJ/m2, respectively. Then E-glass fiber (woven)-reinforced polypropylene-based composites (50 wt% fiber) were fabricated and the mechanical properties were compared with those of the jute-based composites. It was revealed that E-glass fiber-based composites had almost double the mechanical properties as compared to jute composites. The interfacial shear strength of the jute and E-glass fiber-based systems was investigated and found to be 2.13 and 4.66 MPa, respectively, measured using the single-fiber fragmentation test. Fracture sides after flexural testing of both types of the composites were studied by scanning electron microscope and the results revealed poor fiber matrix adhesion for jute-based composites when compared to that of the E-glass fiber composites.

Mechanical and Electrical Properties of Jute Fabrics Reinforced Polyethylene/Polypropylene Composites: Role of Gamma Radiation

Jute fabrics reinforced polyethylene (PE), polypropylene (PP) and mixture of PP+PE matrices based composites (50 wt% fiber) were prepared by compression molding. It was found that the mixture of 80% PP + 20% PE hybrid matrices based jute fabrics reinforced composites performed the best results. Gamma radiation (250–1000 krad) was applied on PP, PE and jute fabrics then composites were fabricated. The mechanical properties of the irradiated composites (500 krad) were found to increase significantly compared to that of the non irradiated composites. Electrical properties like dielectric constant, loss tangent and conductivity with temperature variation of the composites were studied.

Mechanical, Degradation, and Interfacial Properties of Synthetic Degradable Fiber Reinforced Polypropylene Composites

Polypropylene (PP) matrix synthetic phosphate based degradable fiber reinforced unidirectional composites (10% fiber by weight) were fabricated by compression molding. Tensile strength (TS), tensile modulus (TM), elongation at break (%), bending strength (BS), bending modulus (BM), and impact strength (IS) were found to be 38 MPa, 1.5 GPa, 12%, 44 MPa, 4.9 GPa, and 7.58 kJ/m 2 respectively. Degradation tests of the fibers and composites were performed for six months in aqueous medium at room temperature (25°C). After six months, the mechanical properties of the composites retained almost 80% of their original properties. The interfacial shear strength (IFSS) of the composites were also measured by single fiber fragmentation test (SFFT). The IFSS of the composite system was found 5.9 MPa that indicated good fiber matrix adhesion.

Comparative Studies of Mechanical and Interfacial Properties between Jute and Bamboo Fiber-Reinforced Polypropylene-Based Composites

Jute and bamboo fiber-reinforced polypropylene (PP) based composites (50 wt% fiber) were fabricated by compression molding. Tensile strength (TS), bending strength (BS), tensile modulus (TM), and bending modulus (BM) of the jute-reinforced PP composite were found to be 48, 56, 900, and 1500 MPa, respectively. Then, bamboo fiber-reinforced PP-based composites (50 wt% fiber) were fabricated and the mechanical properties evaluated. The TS, BS, TM, and BM of bamboo-reinforced PP composites were found to be 60, 76, 4210, and 6210 MPa, respectively. It was revealed that bamboo fiber-based composites had higher TS, BS, TM, and BM compared to jute-based composites. Degradation tests of the composites (jute fiber/PP and bamboo fiber/PP) were performed in soil at ambient conditions for up to 24 weeks. It was revealed that bamboo fiber/PP composite retained its original mechanical properties higher than that of jute fiber/PP composite. The interfacial shear strength of the jute and bamboo fiber-based composites was investigated using the single-fiber fragmentation test and it was found to be 2.14 and 4.91 MPa, respectively. Fracture sides of the composites were studied by scanning electron microscope, and the results revealed poor fiber matrix adhesion for jute fiber-based composites compared to that of the bamboo fiber-based composites.

Effect of Gamma Radiation on the Physico-Mechanical and Electrical Properties of Jute Fiber-Reinforced Polypropylene Composites

Hessian cloth (jute fiber)-reinforced polypropylene (PP) composites were prepared by compression molding. The fiber content in the composites was about 50%. The resulting composites and also PP sheets were irradiated under gamma radiation of various total doses (250—1000 krad) at the rate of 600 krad/h. It was found that by using gamma radiation, the mechanical properties of the PP sheets and composites were improved. Gamma radiation dose of 500 krad showed better mechanical properties than that of other doses. Tensile strength and tensile modulus of the PP sheets improved 28% and 26%, respectively, and for composites 16% and 45%, respectively. On the other hand, bending strength and bending modulus of the PP sheet improved 16% and 125%. For composites, bending strength, bending modulus, and impact strength improved 12%, 38%, and 62%, respectively. Water uptake of the composites at 25°C was measured and it was found that treated samples had lower water uptake properties. It was found that the dielectric constant is higher for the treated composite than that of the untreated one. The transition temperatures were found to be 80°C for untreated and 75°C for irradiated composites, respectively. Conductivity of the composites decreases due to irradiation.