Pratima Parashar

Mechanical properties of guar gum, polyacrylonitrile and their composites

Abstract Thin films of guar gum (GG)—a natural polymer, polyacrylonitrile (PAN)—a synthetic polymer, GG grafted with PAN, and a composite of GG and PAN were made by the usual solvent evaporation method. All the four films were subjected to Vickers microhardness tests in order to explain surface morphology, crystallinity and composition. The breaking strength of all the films was also determined. The load dependence of Vickers microhardness, Hv, has been explained by a logarithmic index, n. The small stress behaviour of Hv was found to be related to the Newtonian resistance pressure of the specimen itself.

Effect of Gamma-Ray irradiation on the mechanical strength of polystyrene-ferrocene composite

Abstract Thin films of polystyrene-ferrocene (PSFe) composite were irradiated with various doses of gamma irradiation ranging from 4·1 to 25·3 Mrad. The Vickers hardness number (Hv) was calculated for pure and irradiated specimens. It was used to analyse mechanical strength at a saturation load of 100 g. The mechanical strength was found to increase with irradiation dose up to 12 Mrad. Brittleness of the composite PS-Fe was found to occur at a higher dose of 25 Mrad as compared to 15 Mrad for polystyrene. Further, fracture toughness, brittleness index and yield strength were calculated for various irradiated specimens consequent to crack propagation in the specimens.

Mechanical strength of blends of Eudragit RL 100 and poly(methyl methacrylate)

Plaques of blends of Eurdragit RL 100 and poly(methyl methacrylate) (PMMA) with different weight percentage ratios were obtained by compression moulding at 150°C. The mechanical strength of these blends was studied by a microindentation technique. The results show a decrease in brittleness and increase in hardness, toughness and yield strength by addition of PMMA to Eudragit.

Studies of the microhardness of glass fibre reinforced polymer (GFRP)

Abstract The Vickers microhardness test has been carried out on GFRP specimens at different loads ranging from 5 to 160 g. The Vickers hardness number (H v )-load behaviour has been explained on the basis of strain hardening phenomena. This reveals that the value of H v is greater at small stresses and it becomes independent of load beyond 110 g. In this range the value of the logarithmic index, n, is 2. The non-linear behaviour of microhardness with load has three different values of logarithmic index. Further, the dependence of load on H v in GFRP specimens has been explained on the basis of Newtonian resistance pressure as proposed by Hays and Kendall.

Recent Trends in Nano Metal Polymer Composite

The present paper reviews recent patents on polymer-inorganic particle blends with reference to silver particu- late films on softened polymer composites of polystyrene (PS)/ poly (2-vinyl pyridine) (P2VP) and PS/ poly (4- vinylpyridine) (P4VP) deposited at a rate of 0.4 nm/s held at a temperature of 457 K in vacuum of 8� 10 -6 Torr by evapora- tion. There has been continuous development in the field of polymer-inorganic nano particle blends. Polymer-inorganic particle blends are incorporated into structures involving interfaces with additional materials can be used for forming de- sirable devices. Polymer blends with a vast variety of characteristics, architectures with properties that are often not accessible with individual components are prepared. A method is used to form metal nanoparticles having a desired shape and size by combining in a single solution, solvent, metal ions and copolymers under conditions such that metal nanopar- ticles are formed. Nanoparticles layers can be distributed on a substrate using various methods. Blending of insulating polymers with metal particle provides an insulating cover and cost reduction. Various methods are used to design nano- particle on a dielectric substrate for desired applications like charge storage in electronic devices, system and optical sen- sors.

A microhardness test to analyse thermal change in guargum, polyacrylonitrile and their blends

Abstract The Vickers microhardness test is found to be a suitable analytical method for studying thermal change in thin films of polymers. It is utilised to analyse the effect of thermal pretreatment (annealing and quenching) on the surface microhardness of guargum (GG); a natural polymer), polyacrylonitrile (PAN; a synthetic polymer) and their cast blends, guargum-grafted-polyacrylonitrile (GG-g-PAN) and polyacrylonitrile-guargum (PAN-GG). Annealing at various temperatures reveals the change in configuration and crystallinity of thin films of polymers. Peak values of hardness are found to occur in GG, PAN and PAN-GG but not in GG-g-PAN. The quenched hardness for GG is found to be nonlinear with temperature. However, for other polymers quenched hardness decreases, initially, up to a certain temperature and then starts increasing; such temperatures for PAN, PAN-GG and GG-g-PAN are 86, 66 and 86°C, respectively. The behaviour of polymer blends on quenching can be represented by a calculated value of the exponent which is 0·62 and 0·75 for GG-g-PAN and PAN-GG, respectively.

Silver Particulate Films on Compatible Softened Polymer Composites

It is difficult to disperse silver nanoparticle homogeneously into a polymer matrix by ex situ methods because of easy agglomeration of nanoparticles. At present, it is possible to obtain nanoparticles of different shape and size in nanostructured polymeric environment using various polymeric systems and different approaches. Numerous methods used toxic and potentially hazardous reactants. Increasing environmental concerns over synthesis route resulted in an attempt to adopt eco friendly methods.