Post-consumer Recycled PET Packaging for Fresh Berries: A Comparative Study between Incorporating an Antifungal Agent Superficially and into the Main Body of the Packaging

This study proposes to incorporate an antifungal agent (potassium sorbate, KS) to post-consumer recycled polyethylene terephthalate (PCRPET), by adding KS to the dip solution through which PCRPET normally passes after extrusion, in order to acquire a non-stick silicone coating, which prevents individual packages from adhering to each other while stacked. This method of imparting antifungal activity to the packaging is far more advantageous than adding KS to the extruder feed because it results in virtually no alterations to the colour and mechanical properties of PCRPET, which is a major issue when KS is added to the extruder feed. The antifungal efficacy of the active packaging was demonstrated against Botrytis cinerea growth by a novel method which mimics the action of the antifungal agent under fruit contact conditions. A reduction by 2 log cycles was observed when the initial concentration of the mould was 10⁵ conidia/mL. The active packaging was effective over a test period lasting 6 months. The packaging microstructure was visualized by scanning electron microscopy (SEM); its thermal properties were characterized using a differential scanning calorimeter (DSC); its optical properties were characterized using CIE Lab colorimetry; and its mechanical properties were characterized by measuring resistance to dynamic compression. The mechanical properties showed no significant difference (P?>?0.05) with those of the control (PCRPET without KS), and despite a statistically significant difference (P?<?0.05) in the colour parameters (L*, a* and b*), the total colour difference (ΔE*) was found to be too small to be visually noticed. This study achieved the aim of adding antifungal activity to PCRPET packaging with little or no perceptible changes to its mechanical, thermal and optical properties and virtually no changes being made to the standard high-speed packaging production line.     

Mathematical aspects of Rietveld refinement and crystal structure studies on PbTiO3 ceramics

The core mathematics, goodness-of-fit parameters of Rietveld refinement technique is introduced for structural analysis of crystalline materials not available as single crystals. X-ray diffraction (XRD) patterns of PbTiO₃ compound prepared by following solid-state route, suggests it to be in single crystal form. All the observed peaks could be indexed to P4mm space group with tetragonal symmetry. XRD pattern is analysed by employing Rietveld method. The unit cell parameters are found to be a = b = 38987 (0.0008) Å and c = 4·1380 (0·0009) Å. The axial ratio c/a and unit cell volume are found to be 1·0614 and 62·896 (0.023) ų. Bond lengths and angles are calculated using the cell parameters. Using the Rietveld refinement parameters a stable PbTiO₃ structure is suggested.     

Indian thermal power plant challenges and remedies via application of modified data envelopment analysis

This paper evaluates the performance of coal‐fired thermal power plants in India for the year 2008–2009 using data envelopment analysis (DEA); subdividing the power plants into three categories depending on their scale—small, medium, and large. The classical DEA model is analyzed to identify the efficient ones from the whole gamut of plants run by various organizations of the central government, state government, and private sector. Slack analysis is carried out to explore the specific areas that need to be focused on, in quantitative terms, for the overall efficiency improvement. Further efficiency evaluation is extended from a single criterion‐based conventional approach to a multiple criteria oriented approach, and the resulting DEA models are more efficient and flexible in many aspects, particularly in discriminant and weight analysis. Results of multicriteria DEA (MCDEA) are substantiated with cross‐efficiency analysis by deploying the weights obtained by the MCDEA in the cross‐efficiency analysis. On the basis of the insights provided by the outcome of the analysis, both qualitative and quantitative measures are proposed for improvement of the plant performances. The result of this analysis may assist the management of the power plants to introspect and review their systems and processes for optimal use of resources. The methodology adopted in the present work can also be employed for deeper understanding of power plants in other parts of India as well as in other countries.     

Effect of electrical properties on gas sensitivity of polypyrrole/cds nanocomposites

In the present work, polypyrrole (PPy) nanocomposites were synthesized using ferric chloride (FeCl₃) as an oxidant by in situ polymerization at room temperature. Cadmium sulfide (CdS) nanoparticles were synthesized by ultrasonication technique with size ranging between 60 and 110 nm. The PPy/CdS nanocomposites were prepared by taking 1–3 wt % loading of CdS to measure the electrical conductivity. The PPy nanocomposites were characterized by using FTIR, X‐ray diffraction, UV, and SEM. Furthermore, these PPy/CdS nanocomposites were investigated to study their effect of electrical properties on gas sensitivity of ammonia and LPG. The nanocomposites showed improvement in conductivity and sensing response toward 250 ppm NH₃ was found to be maximum (4.2) compared with 100 and 500 ppm NH₃ gas, whereas in the case of LPG, it showed sensitive response. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42379.     

Numerical Study and Experimental Validation of Effect of Varying Fiber Crack Density on Stiffness Reduction in CFRP Composites

Representative volume element (RVE) has commonly been used to predict the stiffness of undamaged composite materials using finite element analysis (FEA). However, never has been an independently measured true microstructural damage quantity used in FEA to predict composite stiffness. Hence, in this work, measured fiber crack density in unidirectional fiber composite (generated using controlled fatigue loading) was used to predict reduction in stiffness using a RVE. It was found that the stiffness changes with change in depth of the volume element along the fiber direction and asymptotically reaches a constant value beyond a critical length called representative depth. It was argued that this representative depth should be more than the minimum of two characteristic length scales, twice of ineffective length and average length of broken fibers. Effective stiffness obtained from FEA of the optimum-sized RVE was in excellent agreement with the experimental results for given microstructural damage state.     

Mesua ferrea L. seed oil‐based epoxy resins

Exhaustion of fossil fuels, tremendous increase of materials demand, and unpredictable prices of petroleum based products urge upon the sustainable development. Three different epoxy resins have been synthesized from monoglyceride of Mesua ferrea L. seed oil and epichlorohydrin with and without other dihydroxy compound like tetrabromobisphenol‐A (TBPA) and bisphenol‐A (BPA). The synthesized epoxy resin were characterized by measurement of physical properties like epoxy equivalent, viscosity, hydroxyl value, saponification value, acid value, etc., and spectroscopic techniques like FTIR and ¹H NMR. High thermostability with initial decompositions temperature of 225–265°C was observed for the cured resins and 75 mol % BPA based resin exhibits the highest thermostability. Newtonian flow behavior was observed for all resins as indicated by the rheometric study (CVO 100). The flame retardency rating of TBPA based epoxy was found to be V1 as tested by UL 94. The performance characteristics as coating materials were studied by the measurement of gloss, impact resistance, scratch hardness, tensile strength, elongation at break, adhesive strength, and chemical resistance. The results indicate the suitability of the synthesized resins as coating materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Vegetable oil based highly branched polyester/clay silver nanocomposites as antimicrobial surface coating materials

The unison of nanotechnology and polymer science enables the development of novel silver-based polyester nanocomposite as an antimicrobial coating material. Highly branched polyester/clay silver nanocomposites based on vegetable oil with different loadings of silver were prepared via reduction of silver salt by employing dimethylformamide as solvent as well as reducing agent at room temperature. Organically modified montmorillonite clay of 2.5 wt% was used as the nanofiller for the property improvement of the pristine polymer. The highly branched polyester resin was synthesized by condensation of 2,2-bis(hydroxymethyl) propionic acid with Mesua ferrea L. seed oil based carboxyl terminated pre-polymer, as reported earlier. FTIR, UV–vis, XRD, SEM and TEM studies substantiate the formation of well-dispersed silver nanoparticles within the clay gallery with an average size of 15 nm. The thermostability of the silver nanocomposites obtained by thermogravimetric analysis was enhanced by 20 °C. The mechanical properties such as tensile strength and scratch hardness were improved 4.5 and 2.6 units respectively and impact resistance improved a little by nanocomposites formation. The antimicrobial efficacy of the as-prepared silver nanocomposites was also premeditated and highly antibacterial activity against Gram negative bacteria (Escherichia coli and Psuedomonas aeruginosa) was observed. Excellent chemical resistance in various chemical media except in alkali has also been noticed. The study reveals that the polyester/clay silver nanocomposites based on vegetable oil show the potential to be applicable as antibacterial surface coating materials.     

Catalytically Active Vegetable‐Oil‐Based Thermoplastic Hyperbranched Polyurethane/Silver Nanocomposites

Sunflower oil‐based HBTPU/Ag and LTPU/Ag nanocomposites have been prepared by in situ catalytic reduction of a silver salt. The virgin polymer and their nanocomposites are soluble in various polar organic solvents and amenable for both solution‐casting and hot pressing. XRD, TEM, and UV spectroscopic analyses ascertained well‐dispersed, narrow‐sized Ag nanoparticles. Tensile testing, dynamic mechanical, thermogravimetric, and DSC analyses showed desirable mechanical and thermal features with improvement upon incorporation of Ag nanoparticles and the presence of a hyperbranched component in the nanocomposites. RSM has been used to evaluate the catalytic efficacy of the nanocomposites.

     

Evaluation of Mesua ferrea L. seed oil modified polyurethane paints

Two types of stoving paints have been prepared from Mesua ferrea L. seed oil (MFLSO) modified poly(urethane ester) (PUE) binder systems. One stoving paint system was prepared from partially butylated melamine formaldehyde (MF) resin modified MFLSO-based PUE (70:30 weight ratio) and other one comprised of bisphenol-A-based epoxy resin modified with MFLSO-based PUE (50:50 weight ratio). Paints made with these two resin systems as binders were evaluated against the standard paint system. The physical properties of the paint systems viz. non-volatile content, specific gravity, viscosity, drying time, flexibility, adhesion, scratch hardness, gloss, etc. and chemical properties such as corrosion resistance, salt spray resistance, UV resistance, etc. were measured as per the standard methods and were compared. Thermal stability and surface morphology of the paints were also studied by using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. The performance characteristics of both the test paints were found to be comparable with the corresponding industrial standard paints. Out of the two test paints, the epoxy modified PUE-based stoving paint has been found to be preferred.