Advanced Materials Research Vols. 488-489

Abstract: The application of hydroxyl terminated polyethylene terephthalate (PET-OH) as a starting pre-polymer to react with polymeric methylene di-isocyanate (p-MDI) for synthesis of polyurethane as a wood-composite binder was studied. The PET-OH was modified from waste polyethylene terephthalate (PET) bottles by glycolysis reaction. The effect of weight ratios of binder and rubber-wood sawdust particles and the mole ratios of hydroxyl (OH) of PET-OH and isocyanate (NCO) of p-MDI on mechanical properties were investigated. The properties of wood-polymer composites from PET-OH were also compared with the polyurethane composites from polyethylene glycol (PEG) as a commercial polyol. It was found that mechanical properties of wood-polymer composites increased with the increase of binders and polyol contents and then decreased and PET-OH showed the greater properties than PEG. The ratio of wood particle and the binder of 60:40 by weight and the ratio of OH and NCO of 0.01:1 by mole gave the best mechanical properties.

Abstract: A structural composite is a material system consisting of two or more phases on macroscopic scale whose mechanical performance and properties are designed to be superior to those of the constituent materials acting independently. One of the phases is stiffer and stronger and is called reinforcement and less stiff and weaker phase is known as matrix. This paper presents an experimental analysis of the dynamic characteristics of the unidirectional fiber composite as functions of fiber orientation, temperature, frequency and ramp rate. Dynamic characteristics of glass fiber composite are measured using dynamic machine analyzer (Triton 2000) in three point flexure bending. Micromechanical finite element model is modeled in NISA FEM software and damping of composite material is predicted and results are compared with experimental result.

Abstract: The effect of electromagnetism on the shear rate and the apparent viscosity of the high density polyethylene/ultra high molecular weight polyethylene (HDPE/UHMWPE) blends are carried out by the different processing ways of the vibration capillary rheology, which is to be discussed. The mechanical properties and surface of blown films and the blend DSC curves of the of the vibration extruder are also to be discussed. The results show that the effect of vibration on the viscosity of the blends by direct blending was prominent. The mechanical properties and surface of the blown films made under the vibration state are much better than those under the static state.

Abstract: We report, synthesis and antifungal activities of CuO nanoparticles. Particles are prepared through sol-gel method. X-ray diffraction studies show the particles are monoclinic (crystalline) in nature. Scanning electron microscopic measurements are carried out to understand the morphology of the prepared particles. Energy-dispersive X-ray spectroscopic measurements show that the prepared particles containing Cu and O. To identify the local structure of the particles Fourier transform infra red (FTIR) spectroscopic measurements were carried out showing vibrational bands of Cu-O and O-H band. Anti fungal studies were performed on the set of fungal using disk diffusion method and found that the prepared particles are suitable for antifungal activities.

Abstract: Polylactide biodegradable composite films were prepared via melt extrusion using a twin screw extruder. The effects of type and content of nucleating agent and cooling rate on the thermal and tensile properties of these films were investigated. Two types of nucleating agent, talc and nano precipitated calcium carbonate (NPCC), were studied at various contents from 0 to 2.0 phr. Nonisothermal crystallization behavior of composites was characterized by a differential scanning calorimetry (DSC). The cooling rate was varied from 1 to 10°C/min. The results indicated that the presence of nucleating agent significantly influenced on thermal and tensile properties of the PLA composite films. DSC thermograms revealed that the addition of nucleating agent on the PLA films led to an increase of crystallization temperature (Tc), crystallization rate, and degree of crystallization (χc) compared to the neat PLA. These behaviors could be noticed in both the nucleated PLA films with NPCC and talc. In contrast, the Tc and crystallization half-time (t _1/2) of these films significantly decreased when the cooling rate increased from 1 to 10°C/min. However, thermal stability of the films decreased when the nucleating agent content increased, especially that of the composites with NPCC.

Abstract: Finite element analysis has been used to find out eigen values and mode shape for fiber reinforced composite plates. FRC plates are important structural elements in modern engineering structures. Vibrations of laminated composite plates have been the subject of significant research activities in recent years. Last two decades have witnessed continued development of advanced composite and other high performance aerospace materials with increased specific strength and modulus, longer fatigue life, higher combat survivability etc. Advanced composite laminates extend the possibility of optimal design through the variation of stacking sequence and fiber orientation, known as composite tailoring. The benefits that accrue from this are not attainable without solving the complexities that are introduced by various coupling effects, such as bending–stretching and bending-twisting. Even, as the matrix material is of relatively low shearing stiffness as compared to the fibers, a reliable prediction of frequency response of laminated plates must account for transverse shear deformation. A four noded quadrilateral finite element is considered for the study of frequency response of composite plate. An analytical solution to the boundary value problem of free vibration response of arbitrarily laminated plates subjected to an admissible boundary condition is presented. A rectangular fiber reinforced composite plate is modeled in FEM software (NISA 15) and natural frequencies, mode shapes are obtained and are compared with the available analytical solutions.

Abstract: Extensive interest in bone tissue engineering focuses on bio-degradable materials based on natural polymers. One of these polymers is chitosan which is deacetylated derivative of chitin. The paper presents preparation of chitosan scaffolds containing collagen and hydroxyapatite by electrolytic method. Chitosan dissolved in acetic acid forms chitosan acetate which is polyelectrolyte (protonated group NH3⁺). The flow of current through a solution of chitosan acetate causes its reduction and accumulation of chitosan on cathode. Formed structure is highly hydrated porous hydrogel. Hydrogel structure can be coated (in the process of electrodeposition) by nano-silver having a bactericidal effect. Subsequently hydrogel was frozen at -37°C for 24h and freeze-drying. Obtained scaffold has a high porosity (more than 88%) with average pore size of about 0.1-3 μm (micropores) and 0,1- few millimeters (macropores).

Abstract: The impact behaviors of glass fibre reinforced/epoxy nanocomposites were studied by experimental using instrumental falling weight testing machine at three different energy levels. Two types of laminates were prepared by hand lay-up method with varying nanoclay into the epoxy in a 1%, 3% and 5%, respectively. The structures of nanocomposites were studied using X-ray diffraction (XRD). It was found that the nanoclay was orderly exfoliated in the epoxy resin. The impact properties of maximum load and energy absorption were determined. It was observed that addition of 3% nanoclay into the epoxy, the maximum load was enhanced by 32% and energy absorption by 24% at the energy level of 24.89J. The impact fractured surface morphology of the glass fibre/epoxy nanocomposites was analyzed using scanning electron microscopy (SEM).

Abstract: The focus of this study is to investigate the influences of ethylene octene copolymer (EOC) and carbon nanotubes (CNTs) on the mechanical properties (tensile and flexural properties) and thermal stability of polypropylene (PP)-based thermoplastic elastomer nanocomposites. The PP/EOC blends were prepared at two different weight ratios, 80/20 and 70/30 (w/w) PP/EOC, and each blend was compounded with a very low loading of CNTs (0.5-2 parts by weight per hundred of the PP/EOC resin). Both PP/EOC blends exhibited a higher elongation at break but a lower tensile strength, Young’s modulus and flexural strength as compared with those of the neat PP. However, the addition of CNTs caused a slightly change in the tensile strength and flexural strength but a more significant change in the Young’s modulus and elongation at break. The Young’s modulus and elongation at break of the PP/EOC blends were improved by filling with the appropriate loading of the CNTs. Thus, the combined use of EOC and CNTs can provide the balanced mechanical properties to the PP. Moreover, thermogravimetric analysis showed an improvement in the thermal stability of PP by the presence of both EOC and CNTs.

Abstract: To obtain polypropylene/microcrystalline cellulose (PP/MCC) composites, PP was melt mixed with three loadings (5, 10 and 15 phr) of MCC prepared by hydrolyzing cotton waste with hydrochloric acid. The prepared MCC was characterized for its crystal structure, particle size, thermal stability and morphology. The tensile properties and thermal stability of PP/MCC composites with and without maleic anhydride-grafted polypropylene (MAPP) compatibilizer were investigated using the universal testing machine and thermogravimetric analyzer, respectively. The obtained results showed that the tensile strength, Young’s modulus and thermal stability of the composites were enhanced in a dose dependent manner, whilst the elongation at break was deteriorated with increasing MCC loadings, as compared with the neat PP. However, these properties were all improved with the addition of MAPP into the composites. This work showed that MCC and MAPP could be effectively used as reinforcing agent and compatibilizer, respectively in the PP matrix.