P.C. Thomas

St. Berchmans College, Changanacherry, Kerala, India

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Publications (6)8.73 Total impact

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    ABSTRACT: The diffusion and transport behavior of nitrile rubber nanocomposites was studied with respect to different types of filler and also different types of solvents. The nitrile rubber nanocomposites showed considerable variations in the molecular transport owing to the tortuosity of path, decreased segmental mobility, and difference in particle geometry. As the matrix under consideration is polar, the behavior of the filled systems in aniline was also studied with a view to understand the polar–polar interaction between the filled matrix and the solvent. The oil repellency as a result of filler addition in the matrix was investigated by studying oil uptake of the nanocomposites. In all these investigations, it has been observed that the filler geometry played an important role in controlling the molecular transport through the polymer matrix. The layered silicate‐filled system showed better solvent resistance and hence minimum solvent uptake in polar and nonpolar solvents and better oil repellency followed by titanium dioxide and calcium phosphate filled systems. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
    Polymer Composites 12/2012; 33(12). DOI:10.1002/pc.22369 · 1.63 Impact Factor
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    ABSTRACT: The morphological, mechanical, and thermal stability of Nitrile rubber nanocomposites reinforced with fillers such as layered silicate (LS), calcium phosphate (CP) and titanium dioxide (TO) having different particle size and chemical nature were analyzed. The results revealed that the filler geometry played an important role on the mechanical and thermal stability of the composites. Calcium phosphate and titanium dioxide filled systems showed comparatively better mechanical and thermal stability compared to neat rubber. The activation energy needed for the thermal degradation was found to be higher for layered silicate filled system. DSC (Differential Scanning Calorimetry) analysis revealed a change in the Tg values as a result of the addition of fillers. This was more prominent with the case of layered silicate filler addition in comparison with calcium phosphate and titanium dioxide. The heat capacity values of the nanocomposites were carefully evaluated. The (∆Cp) with values obtained for different nanocomposites were correlated with the degree of reinforcement. It can be assumed that more polymer chains are attached on to the surface of the filler and there exists an immobilized layer around the filler surface and the layers do not take part in the relaxation process. The FTIR spectrum of the different samples highlighted the possible filler matrix interaction. The filler dispersion and aggregation in the polymer matrix were analyzed using X-ray diffraction studies (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM).
    Journal of Polymer Research 07/2011; 18(6):2367-2378. DOI:10.1007/s10965-011-9651-1 · 1.92 Impact Factor
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    ABSTRACT: Acrylonitrile-butadiene rubber (NBR) nanocomposites with layered silicate (LS), calcium phosphate (CP), and titanium dioxide (TO) of different particle size were prepared in an open two-roll mixing mill at different filler loading in presence of sulphur as vulcanizing agent. The layered silicate (LS) filled system showed outstanding enhancement in mechanical properties in comparison with nanocalcium phosphate (CP) and titanium dioxide (TO). The variations in properties can be attributed to the extent of intercalation/exfoliation, which was highly influenced by the filler size. The layered silicate filled system at 20 phr showed nearly 349% increase in tensile strength compared to pure NBR whereas an increase of 110% and 84% were shown by CP and TO filled systems respectively. The modulus enhancements were in the order of 200%, 63% and 22%, respectively compared to the unfilled system. The increase in tear resistance was in the order of 230%, 115%, and 41% respectively for the filled systems in comparison with unfilled NBR. The significant enhancements in mechanical properties were supported by the morphological analysis. POLYM. COMPOS., 31:1515–1524, 2010. © 2009 Society of Plastics Engineers
    Polymer Composites 09/2010; 31(9):1515 - 1524. DOI:10.1002/pc.20938 · 1.63 Impact Factor
  • T.E. Jose · P.C. Thomas · K. Jayanarayanan · J. Mathew · K. Joseph ·
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    ABSTRACT: Natural fibre-reinforced thermoplastic composites have a significant role in non-structural applications. Natural fibres are biodegradable, renewable and of low cost, high toughness and possess good thermal properties. This work involved the study of solvent absorption of cotton/polypropylene (PP) side-by-side commingled composites in different solvents, its variation by chemical treatments, temperature, fibre content etc., the extent of tensile property deterioration by solar radiation in a solar light concentrator and by water diffusion. It was observed that though cotton is highly hydrophilic, the diffusion was a matrix-dominated phenomenon. The extent of moisture absorption increased with the fibre content but decreased on treatment with maleic anhydride-modified PP. The former added a greater number of hydrophilic hydroxyl groups while the latter consumed them and enhanced the fibre-matrix interfacial adhesion. Increase in temperature accelerated the rate of moisture absorption and reduced the time required for equilibrium swelling. Exposure to sunlight in solar concentrator deteriorated mechanical properties such as tensile strength and tensile modulus by weakening the fibre-matrix interfacial adhesion and by chain scission.
    Polymers and Polymer Composites 01/2010; 18(2):103-112. · 0.27 Impact Factor
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    ABSTRACT: The dynamic mechanical properties of cotton/polypropylene (PP) commingled composite system was studied with reference to the fiber content, chemical treatments with potassium permanganate and maleic anhydride modified PP, processing conditions and applied frequency. Side by side commingling of matrix and reinforcing fibers was adopted for the fabrication of composite laminates as they provide the shortest melt flow distance during the melting of matrix fibers. This method can also be used for the recycling of textile wastes. The storage modulus was found to increase with the fiber content across a range of temperatures. The loss factor was found to decrease with the increase in fiber content while the glass transition temperature increases. The chemical treatments increase the value of storage modulus. A master curve was constructed and also made a comparison between the experimental results and the theoretically predicted values. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
    Journal of Applied Polymer Science 12/2009; 114(5):2624 - 2631. DOI:10.1002/app.30826 · 1.77 Impact Factor
  • E. J. Tomlal · P. C. Thomas · K. C. George · K. Jayanarayanan · K. Joseph ·
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    ABSTRACT: Natural fibers can be used as reinforcements in thermoplastic non-structural applications. Commingling them with matrix fibers lowers the melt flow distance of molten matrix during the processing. In this study, polypropylene (PP) and textile cotton fibers were commingled and fabricated to composite laminates. Process variables like temperature, pressure, and holding time affect the mechanical properties like impact strength and tear resistance. Fiber content and winding pattern or fiber orientation were also important for the optimization of the mechanical properties. The modification of the interface by chemical treatments of the matrix or reinforcement with reagents like potassium permanganate, benzoyl peroxide, and maleic anhydride modified PP enhances some mechanical properties like tear strength of cotton fiber-reinforced PP commingled composite systems. Fiber content, treatments, and moisture also varies dielectric constant and volume resistivity.
    Journal of Reinforced Plastics and Composites 06/2009; 29(12):1861-1874. DOI:10.1177/0731684409338748 · 1.50 Impact Factor