Exploring Ag-doped Mullite as High Dielectric and Antimicrobial Reinforcement with Polybenzoxazine Matrix

The present work describes the development of high k dielectric aluminosilicate and its application as reinforcement with polybenzoxazine matrix to achieve high dielectric and antimicrobial nanocomposite. Initially, dielectric constant value of mullite was found to increase with respect to the percentage of Ag in mullite lattices and reached a maximum of 14.9, when doped with 5?mol%. Data from antimicrobial assay also suggest that, the zone of inhibition expands with respect to embedding silver, and thus 10?mol% of Ag-doped mullite exhibiting the highest antimicrobial property. Since, 3?mol% Ag-doped mullite hold better dielectric, various weight percentages of the same (MA₃) were embedded with polybenzoxazine matrices after its surface modification. Among the resulted nanocomposite, 1.5% of glycidyl-functionalized MA₃/polybenzoxazine not only showed remarkable enhancement in their thermal, dielectric, electrical conductivity but also exhibited a zone of inhibition of 11 and 12?mm against Escherichia coli and Pseudomonas aeruginosa, respectively. The enhanced thermal, dielectric, and antimicrobial properties will make this material as a suitable candidate in printed circuit board application in particularly for cold weather climatic conditions.     

Mechanical properties,thermal profiles,and microstructural characteristics of Al-8 %SiC composite welded using pulsed current TIG welding

Journal of Mechanical Science and Technology - This experimental study on Al-SiC composite investigated the temperature distribution and microstructural characterization during pulsed current...     

Thermal and mechanical properties of functionalized mullite reinforced unsaturated polyester composites

This work studies the development of varying weight percentages (0.5, 1.0, and 1.5 wt%) of surface functionalized mullite reinforced unsaturated polyester (UP) composites and their thermal, dielectric, water absorption, and mechanical properties. The synthesized mullite was functionalized with vinyltriethoxysilane (VTES). The introduction of vinyl groups on the surface of mullite was confirmed by FT‐IR, TGA, and X‐ray diffraction (XRD) analyses. Varying weight percentages (0.5, 1.0 and 1.5 wt%) of vinyl functionalized mullite (VFM) were incorporated into UP resin with a benzoyl peroxide initiator to obtain composites. The resultant data obtained from thermal, mechanical, dielectric, and water absorption studies, indicate that incorporation of VFM, leads to a significant improvement in the thermo mechanical, dielectric, and moisture resistant properties of the UP composites, compared with those of neat UP matrices. The molecular dispersion of VFM fiber in reinforced UP matrix composites was confirmed by SEM analysis. POLYM. COMPOS., 35:1663–1670, 2014. © 2013 Society of Plastics Engineers     

Photoluminescence and Electrochemical Behaviors of Polybenzimidazole-Grafted Carbon Nanotubes

The luminescence behavior of carbon nanotubes was achieved by grafting polybenzimidazole on its surfaces. The polybenzimidazole-grafted carbon nanotubes composite was analyzed for its optical and electrochemical properties. From the studies, it was observed that the polybenzimidazole emits blue light at 448 nm, whereas the polybenzimidazole-grafted carbon nanotube shows a red shift with corresponding emission at 434 nm. Additionally, the lifetime of exciting electrons has been calculated from the lifetime measurement studies. The polybenzimidazole-grafted carbon nanotube composite also possess 130 F/g of specific capacitance. Micrograph analysis confirms the grafting of polybenzimidazole on the walls of the carbon nanotube.     

Studies on heterocyclic amines based cardanol-benzoxazine for oil-water separation

The present work describes the development of sustainable bio-benzoxazines for oil water separation and its composites for applications where a low dielectric constant is required. In addition, cardanol benzoxazine monomers (C-ida and C-pyta) with low curing temperature were designed with inbuilt catalytic core using two different heterocyclic amines, namely tetra aryl imidazole diamine (ida) and pyridine core triamine (pyta). Cotton fabric coated with poly(C-ida) and poly(C-pyta) show water contact angle values of 160° and 164°, respectively. The oil-water separation efficiency of the polybenzoxazines coated cotton fabrics was 95%. Further, the poly(C-ida) and poly(C-pyta) matrices were reinforced with varying weight percentages (1, 3, 5, 7, and 10 wt%) of glycidylpropoxytrimethylsilane-functionalized biosilica. The benzoxazine matrices and composites obtained were characterized using different analytical techniques in order to assess their molecular structure, cure behavior, thermal stability, morphology, surface, and dielectric behavior. Data obtained from different studies suggest that these matrices and composites can be used as coatings for oil-water separation and high-performance micro-electronics insulation applications under adverse environmental conditions.     

Development and characterization of surface-modified mullite reinforced BMI-toughened epoxy nanocomposites

High-performance diglycidyl ether of bisphenol-A (DGEBA) epoxy-based composite systems with improved thermal stability for advanced structural applications were developed, using bismaleimide (BMI) as toughening agent and surface-modified mullite as reinforcing agent. The nanocomposites developed in the present study are referred to as M/DGEBA–BMI. 95 % by wt. of DGEBA was toughened with 5 % by wt. of BMI and further reinforced with varying weight percentages of (0.5, 1.0 and 1.5 wt%) glycidyl-functionalized mullite to obtain M/DGEBA–BMI nanocomposites. The formation of nanocomposites was ascertained using Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The mechanical and dielectric properties of nanocomposites were investigated by analytical techniques. The thermal behaviour of nanocomposites was characterized using thermogravimetric analyzer and differential scanning calorimeter. Contact angle, surface free energy and percentage water absorption were also studied and reported. Studies suggest that the properties of M/DGEBA–BMI nanocomposites viz; mechanical, dielectric, surface energy and thermal properties improved to an appreciable extent, when compared to those of neat epoxy matrix.