This article evaluates the use of bagasse flour — a waste generated by sugarcane refinery—as a filler in the PVC matrix. The aim of the study is to develop a value-added product from the sugar mills. For this purpose, bagasse powder was obtained after grinding the dried waste from sugar mills having particle sizes of 100—150 µm and <50 µm. In order to evaluate the effect of filler content and alkali treatment of bagasse, several PVC formulations were obtained by dry-mixing PVC compound with filler of varying particle size. The compounds were obtained by blending on a hot roll mill followed by compression molding. The test specimens were punched out from the sheets and the effect of filler content, particle size, and alkali treatment of bagasse powder on the properties of PVC were evaluated. Tensile strength, percent elongation at break, and impact strength of composites decreased whereas stiffness, modulus, and hardness of the composites increased with increasing amount of filler. The particle size had a large effect on the properties of composites, and the filler having particle size <50 µm gave better properties as compared to filler with particle size of 100—150 µm. Some improvement in properties was observed when treated bagasse powder was used as filler. An increase of ∼48% in tensile modulus, ∼10% in thermal stability, and 14% in impact strength was observed as compared to neat PVC at a filler loading of 30 phr. Morphological characterization was done using a scanning electron microscopy. A uniform dispersion of filler was observed.

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The curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) was investigated by differential scanning calorimetry using bis(4-carboxyphenyl) dimethyl silane (CPA) as a crosslinking agent and imidazole as a catalyst. Two exotherms were observed in the absence of catalyst in the temperature range 166-328 • C. A significant decrease in the curing temperature was observed when 0.1% imidazole was used as catalyst. Further increase in the concentration of imidazole resulted in a decrease in the peak exotherm temperature. The effect of stoichiometry of functional groups on the curing behaviour of DGEBA was investigated by taking varying mole ratios of CPA, ranging from 1 to 2.5, keeping the concentration of imidazole as 0.1% w/w. The heat of polymerization ( H) was found to be maximum at a molar ratio of 1:1.75 (DGEBA:CPA). Mixtures of diaminodiphenyl sulfone (DDS and CPA or phthalic anhydride (PA) and CPA in ratios of 1:0, 0.25:0.75, 0.5:0.5, 0.75:0.25) were also used to investigate the curing behaviour of DGEBA. A significant decrease in curing temperature of DGEBA/DDS was observed on partially replacing DDS with CPA, whereas marginal change in the curing temperatures was observed on replacing phthalic anhydride with CPA. The thermal stability of epoxy resin, cured isothermally, was evaluated by recording thermogravimetry/dynamic thermogravimetry traces in nitrogen atmosphere. The percentage char yield was highest for the sample cured using 1.75 mole of CPA.

ABSTRACT:The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) was investigated by differential scanning calorimetry, using varying molar ratios of imideamines and 4,4Ј-diaminodiphenyl sulfone (DDS). The imideamines were prepared by reacting 1 mol of pyromellitic dianhydride (P) with excess (2.5 mol) of 4,4Ј-diaminodiphenyl ether (E), 4,4Ј-diaminodiphenyl methane (M), or 4,4Ј-diaminodiphenyl sulfone (S) and designated as PE, PM, PS. Structural characterization was done using FTIR, 1 H NMR, 13 C NMR spectroscopic techniques and elemental analysis. The mixture of imide-amines and DDS at ratio of 0 : 1, 0.25 : 0.75, 0.5 : 0.5, 0.75 : 0.25, and 1 : 0 were used to investigate the curing behavior of DGEBA. The multiple heating rate method (5, 10, 15, and 20°C/min) was used to study the curing kinetics of epoxy resins. The peak exotherm temperature was found to be dependent on the heating rate, structure of imide-amine, and also on the ratio of imide-amine : DDS used. Activation energy was highest in case of epoxy cured using a mixture of DDS : imide-amine of a ratio of 0.75 : 0.25. Thermal stability of the isothermally cured resins was also evaluated in a nitrogen atmosphere using dynamic thermogravimetry. The char yield was highest in case of resins cured using mixture of DDS : PS (0.25 : 0.75; EPS-3), DDS : PM (0.25 : 0.75; EPM-3), and DDS : PE (0.75 : 0.25; EPE-1).

This article presents the design of Fermi antenna array with improved gain for radar respiration measurement. A six‐element Fermi antenna array working at 5.8 GHz is optimally designed and integrated with the respiration radar system. Specifically, to easily feed the antenna array as well as reduce the total size of the array system, a feeding network based on 0‐degree phase shifters is used along with suitable impedance transformers. The whole system is proposed to function as a radar sensor for respiration rate measurement, which is known as a promising noncontact and noninvasive approach for lung cancer radiotherapy. The measurement results verify the improved performance of the proposed system for radar respiration measurement in motion‐adaptive lung cancer radiotherapy. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1649–1654, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26871

This article describes the curing and thermal behavior of diglycidyl ether of bisphenol A with phthalic anhydride (PA)/pyromellitic anhydride/diaminodiphenyl sulfone (DDS) or a mixture of anhydrides and amines in varying ratios as curing agents. The kinetics of the curing behavior was investigated with a multiple-rate method. The activation energy of the curing reaction as determined in accordance with Ozawa's method was found dependent on the structure of the anhydride and on the ratio of amines to anhydrides. The activation energy was highest with sample DP3 (0.25 : 0.75) and DM3 (0.25 : 0.75). We evaluated the thermal stability of epoxy resin, cured isothermally, by recording thermogravimetric traces in a nitrogen atmosphere. The char yield was highest for resins cured with a mixture of DDS and PA (0.5 : 0.5) and a mixture of DDS and pyromellitic dianhydride (0.25 : 0.75).

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