Investigation of cardanol-based reactive polyamide as a crosslinker in epoxy zinc-rich primer

Cardanol-based reactive polyamides with different amine functionalities were successfully developed by conventional polycondensation mechanism. The synthesis involved 2-step processes of functionalization of cardanol by maleic anhydride followed by its condensation with diethylenetriamine in the second step. The polyamides with different molecular weights were prepared by varying the mole ratios of acid and amine components in the formulation. The developed polyamides were characterized for structural confirmation by FTIR and NMR spectroscopy. These polyamides were then used as crosslinker in conventional epoxy zinc-rich primer. The effect of molecular weights of these polyamides on mechanical, chemical, and solvent resistance properties of conventional epoxy zinc-rich primer was studied and compared with that of commercial polyamide. The anticorrosive properties of the primers were evaluated by humidity resistance test, salt spray test and electrochemical impedance spectroscopy. The study revealed that the epoxy zinc-rich primers cured with cardanol-based polyamide resulted in improved mechanical, chemical, and anticorrosive properties as evaluated by various methods.     

Augmentation of performance properties of maleated SEBS/TPU blends through reactive blending

Meticulous investigation of reactive blending of maleic anhydride grafted styrene–ethylene–butylene–styrene (SEBS-g-MA) and thermoplastic polyurethane (TPU) is carried out to achieve systems with controllable morphology and superior mechanical properties. Two types of SEBS-g-MA (abbreviated as M1, M2) with different maleic anhydride content were used to separately blend with TPU. Formation of imide group from the interaction of isocyanate and maleic anhydride predicted from the plausible reaction scheme was confirmed through Fourier transform infrared spectroscopy. High tensile strength of the blends along with appreciable elongation at break was witnessed. Morphology analyses using scanning electron microscopy and atomic force microscopy exposed a vivid and homogenous droplet morphology in all the blends presumably due to in situ formation of a suitable copolymer at the interface. Differential scanning calorimetry was used to pursue the thermal characteristics of the blends. Melt-rheological behavior of the blends was examined using a rubber process analyzer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48727.     

Effect of γ‐irradiation on glycolysis of PET waste and preparation of ecofriendly coatings using bio‐based and recycled materials

Recycling of postconsumer poly (ethylene terephthalate) (PET) is a worldwide concern due to large increasing volume of these materials produced by society. In the present study, we report the effect of gamma irradiation on degradation of PET and its subsequent effect on glycolysis by using excess ethylene glycol (EG). The results as analyzed by molecular weight determination showed that extent of depolymerization of PET were dose dependent. The doses of 30, 50, 70, and 100 kGy resulted in decrease in the molecular weight by about 15%, 25%, 30%, and 40% respectively. The irradiated waste PET samples were further subjected to glycolysis using EG by conventional and microwave method which resulted in increased yield of monomeric product, bis (2‐hydroxyethylterephthalate) (BHET). The recycled material, BHET, was then used in combination with bio‐based monomers to prepare a new eco‐friendly polyester polyol which was analyzed for hydroxyl, saponification, acid value and further characterized by FTIR, ¹HNMR, and GPC techniques for molecular weight determination. Polyurethane coatings were prepared from the polyester polyol and various commercial polyisocyanate curing agents. The coated films were evaluated for their performance properties. Thermal properties of coatings were investigated by differential scanning calorimetry and thermogravimetric analysis. POLYM. ENG. SCI., 55:2653–2660, 2015. © 2015 Society of Plastics Engineers     

Epoxy resin from cardanol as partial replacement of bisphenol-A-based epoxy for coating application

With continuous depletion of petrochemical feedstock and their rising prices, the chemical industry is now looking for alternative renewable and sustainable materials. Such materials could be processed with various chemistries to produce high performance functional materials for a range of applications, such as plastics, coatings, constructions, pharmaceuticals, and food applications. Cardanol derived from cashew nut shell liquid has a reactive phenolic group and aliphatic double bond that could be exploited to produce novel functional materials for polymer and coating applications. It has previously been used for preparation of phenolics, epoxy, and phenalkamine hardeners. In this study, we report on the preparation of novel epoxy resin from cardanol via simple a two-step reaction. The prepared resin with epoxy equivalent weight of 210–220 gm/eq was analyzed using FTIR and NMR spectroscopy. The epoxy resin was then used as binder along with bisphenol-A-based epoxy resin (DGEBPA) at various weight proportions and cured with different amine hardeners. The cured coatings were analyzed for physical, mechanical, and chemical properties for optimization of the coating formulation. The study conducted showed that 40–60% of DGEBPA resulted in comparable properties to that of completely DGEBPA-based system. Further, thermal and anticorrosive properties of the optimized coatings were also evaluated.     

Development of nanofibrous morphology in LDPE/LLDPE/PP blends and its effect on mechanical properties of blend films

Nanofibrous morphology has been observed in ternary blends of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and isotactic polypropylene (PP) when these were melt‐extruded via slit die followed by hot stretching. The morphology was dependent on the concentration of the component polymers in ternary blend LDPE/LLDPE/PP. The films were characterized by wide angle X‐ray diffraction (XRD), scanning electron microscopy (SEM), and testing of mechanical properties. The XRD patterns reveal that the β phase of PP is obtained in the as‐stretched nanofibrillar composites, whose concentration decreases with the increase of LLDPE concentration. The presence of PP nanofibrils shows significant nucleation ability for crystallization of LDPE/LLDPE blend. The SEM observations of etched samples show an isotropic blend of LDPE and LLDPE reinforced with more or less randomly distributed and well‐defined nanofibrils of PP, which were generated in situ. The tensile modulus and strength of LDPE/LLDPE/PP blends were significantly enhanced in the machine direction than in the transverse direction with increasing LLDPE concentration. The ultimate elongation increased with increasing LLDPE concentration, and there was a critical LLDPE concentration above which it increased considerably. There was a dramatic increase in the falling dart impact strength for films obtained by blow extrusion of these blends. These impressive mechanical properties of extruded samples can be explained on the basis of the formation of PP nanofibrils with high aspect ratio (at least 10), which imparted reinforcement to the LDPE/LLDPE blend. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fuzzy logic–based distributed clustering protocol to improve energy efficiency and stability of wireless smart sensor networks for farmland monitoring systems

Wireless smart sensor networks (WSSNs) are emerging as the physical backbone of the internet of things (IoT) technology. On the basis of the IoT platform, web‐based systems and services are been developing such as e‐surveillance, industrial‐IoT, and precision agriculture. For farmland monitoring systems, WSSNs need to be scalable in terms of coverage area. Sensor nodes are energy‐constrained devices, and hence, many energy‐efficient clustering protocols are developed in the literature. But these methods overload the cluster leaders (CLs) with cluster computation and data communication costs. An improper CL selection may lead to the early death of such nodes and hence does not prolong the network lifetime stability. We propose a fuzzy logic (FL)–based distributed clustering protocol to enhance the energy efficiency of WSSN while maximizing the coverage area. The load of CLs is shared by originators and super‐CLs (SCLs) selected in the network. The wireless link and received signal strength (RSS) are greatly affected by environmental conditions and thus cannot be considered as ideal network parameters. We use FL systems to tackle the uncertainty of such network parameters. The proposed protocol is simulated for different scalable WSSNs. The results indicate that the proposed protocol provides better lifetime stability than the recent conventional protocols. The functionalities of the protocol are proposed considering the recent wireless standards. Hence, the proposed protocol can be suitably implemented for farmland monitoring systems.     

Diester based on castor oil fatty acid as plasticizer for poly(vinyl chloride)

Castor oil is a renewable resource that has potential uses as an environmental friendly material for a range of applications. In recent years, much efforts have been driven to develop alternate plasticizer for medical and commodity plastics due to growing concerns about dioctyl phthalate (DOP) for flexible poly(vinyl chloride) (PVC). In this study, a bio‐based plasticizer was synthesized by a two‐step esterification reaction of castor oil fatty acid (COFA) with benzyl alcohol and octanoic acid in the presence of catalyst (dibutyl tin dilaurate). The structure of the octanoic ester (OE) was confirmed by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, acid value, and hydroxyl value. OE was used as a coplasticizer in PVC for partial replacement of DOP. The addition of OE exhibited good incorporation and plasticizing performance in the PVC sheets. Incorporation of OE resulted in good plasticizing, tensile strength, percentage elongation, exudation, thermal stability, and chemical resistance because of the presence of long carbon chains of COFA. Differential scanning calorimetry (DSC), thermogravimetric analysis, and color measurements were also performed to evaluate the effect of OE. With the increase in OE, DSC and hardness results showed marginal deviation from those obtained for DOP‐plasticized sheets. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40354.     

2D‐GaS as a Photocatalyst for Water Splitting to Produce H2

Using first‐principles local and hybrid density functional theoretical calculations, a thickness‐dependent electronic structure of layered GaS is determined, and it is shown that 2D GaS has an electronic structure with valence and conduction bands that straddle the redox potentials of hydrogen evolution reaction and oxygen evolution reaction up to a critical thickness (<5.5 nm). Here, simulations of adsorption of H₂O on nanoscale GaS reveal that localized electronic states at its edges appear in the gap and strengthen the interaction with H₂O, further activating the surface atomic sites. It is thus predicted that GaS synthesized with a controlled thickness and preferred edges may be an efficient catalyst for photocatalytic splitting of water. Experiments that verify some of the predictions in this study are presented, and it is shown that GaS is effective in absorption of light and evolution of H₂ (887 μmol h⁻¹ g⁻¹) in the presence of aqueous solution of hydrazine (1% v/v). This study should open up the use of nanoscale GaS in conversion of solar energy into environment‐friendly chemical energy in the form of hydrogen.     

Myeloid ABCG1 Deficiency Enhances Apoptosis and Initiates Efferocytosis in Bronchoalveolar Lavage Cells of Murine Multi-Walled Carbon Nanotube-Induced Granuloma Model

The use of carbon nanotubes has increased in the past few decades. Carbon nanotubes are implicated in the pathogenesis of pulmonary sarcoidosis, a chronic granulomatous inflammatory condition. We developed a murine model of chronic granulomatous inflammation using multiwall carbon nanotubes (MWCNT) to investigate mechanisms of granuloma formation. Using this model, we demonstrated that myeloid deficiency of ATP-binding cassette (ABC) cholesterol transporter (ABCG1) promotes granuloma formation and fibrosis with MWCNT instillation; however, the mechanism remains unclear. Our previous studies showed that MWCNT induced apoptosis in bronchoalveolar lavage (BAL) cells of wild-type (C57BL/6) mice. Given that continual apoptosis causes persistent severe lung inflammation, we hypothesized that ABCG1 deficiency would increase MWCNT-induced apoptosis thereby promoting granulomatous inflammation and fibrosis. To test our hypothesis, we utilized myeloid-specific ABCG1 knockout (ABCG1 KO) mice. Our results demonstrate that MWCNT instillation enhances pulmonary fibrosis in ABCG1 KO mice compared to wild-type controls. Enhanced fibrosis is indicated by increased trichrome staining and transforming growth factor-beta (TGF-β) expression in lungs, together with an increased expression of TGF-β related signaling molecules, interleukin-13 (IL-13) and Smad-3. MWCNT induced more apoptosis in BAL cells of ABCG1 KO mice. Initiation of apoptosis is most likely mediated by the extrinsic pathway since caspase 8 activity and Fas expression are significantly higher in MWCNT instilled ABCG1 KO mice compared to the wild type. In addition, TUNEL staining shows that ABCG1 KO mice instilled with MWCNT have a higher percentage of TUNEL positive BAL cells and more efferocytosis than the WT control. Furthermore, BAL cells of ABCG1 KO mice instilled with MWCNT exhibit an increase in efferocytosis markers, milk fat globule-EGF factor 8 (MFG-E8) and integrin β3. Therefore, our observations suggest that ABCG1 deficiency promotes pulmonary fibrosis by MWCNT, and this effect may be due to an increase in apoptosis and efferocytosis in BAL cells.