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Polyurethane-acrylate oligomers are a new class of polyurethane which are produced by the reaction of polyols with diisocyanate and capped by acrylate. There is a growing demand for modification with improved properties of the polyurethane-acrylate. This review covers the following topic: structure, modification of polyurethane-acrylate backbone, reactive diluents, curing, mechanical, optical, thermal behavior, and applications presented herein. The basic understanding of the chemistry and mechanistic aspects of these oligomers has reached a level was tailor-made formulations suitable for a particular application may be selected.

The current study focuses on the development of a formulation of polyester polyurethane (PEPU) samples using castor oil (CO) modified polyester polyol and partially biobased aliphatic isocyanate. The CO modified polyester polyol was synthesized employing transesterification reaction between CO and diethylene glycol in the presence litharge (PbO) catalyst. Subsequently, the modification of CO was confirmed using proton nuclear magnetic resonance (1HNMR) spectra analysis. In the next stage, the biobased polyester polyurethane nanocomposites (PEPUNC) were prepared by incorporating 3 wt% OMMT nanoclay within PEPU through in situ polymerization technique. The produced PEPU was confirmed by Fourier transform infrared spectroscopy (FTIR) and 1HNMR spectra analysis. Further, the degradation properties of developed PEPU subjected to soil-burial, UV exposure and hydrolytic-salt water medium were noted by FTIR spectroscopy. Corresponding weight loss, mechanical measurements and morphological studies through scanning electron microscopy (SEM) analysis were studied. The results showed that the addition of OMMT nanoclay within the PEPU matrix produces significant improvement in the degradation rate which indicated the susceptibility of OMMT nanoclay to humidity upon exposure to soil burial. The produced microorganisms from the soil resulted in significant chemical and morphological changes in the entire structure of the PEPU. Additionally, the highest degradation and percentage of weight loss was observed under soil burial as compared to UV exposure and hydrolytic-salt water medium.

Techniques for separation of gas mixtures obtained from various sources, such as effluents from industries, and biogas, have always fascinated researchers. The advent of mixed matrix membranes (MMMs) has opened up a new window of opportunity for developing membranes coupled with flexibility, processability, and permeability of polymers and selectivity of inorganic nanomaterials. This review is a detailed overview of the effect of various nanofillers on the separation performance of MMMs including the major factors affecting the perm-selectivity and possible solutions for overcoming the emerging challenges. The paper also presents contemporary approaches for cost-effective implementation of MMMs. Methodologies for designing MMMs with improved interfacial morphology to exploit their full potential in tailoring the selectivity efficiency are also discussed in detail. This review can act be a guideline for the future development of high-performance MMMs for industrial applications without compromising long-term separation performance, durability, and stability to processing conditions.

Biobased polymer has taken tremendous attention in recent times. In the present study bio-based polyurethane have been synthesized from the vegetable oil i.e., dehydrated castor oil, 1,4-butanediol and isophorone diisocyanate in presence of a catalyst by solution polymerization method. Then polyurethane nanocomposites were synthesized using different amount of nanoclay (C30B) (1, 3 and 5 wt%). The synthesis of polyurethane and its nanocomposites were confirmed by FTIR and XRD analysis. The mechanical properties such as tensile strength (2.2–4.5 MPa), elongation at break (299%–435%) hardness (46–70) and abrasion resistance (351–201 mg/1,000 cycles) increased with the increase of nanoclay content. The initial thermal degradation temperature found to increase from (220 to 290°C) with the increase of nanoclay content in the nanocomposites. The nanoclay was interacted with the hard segment of the matrix polymer as reflected from the atomic force microscopy studies. Weathering study revealed that nanocomposites have higher weather resistance capacity than pristine polyurethane. It can be concluded that the prepared nanocomposites might be good outdoor topcoat materials.

Itaconic acid (IA), a carbohydrate derived aliphatic dicarboxylic acid, is a potential chemical for the synthesis of renewable resource based resins and polyesters. Owing to the environmental reasons, there is a gradual demand of renewable resources in the chemical industry. Conversely, as a rather depreciated side effect of this growth, novel chemical building blocks are attained, which are not commercially accomplished from petrochemical sources. In this respect, itaconic acid achieved prominent attention and its trifunctional structure leads to the synthesis of novel polymeric materials. This review bestows most relevant information for bio-based resins and polyesters resulted from an itaconic acid and its distinctive properties for various commercial applications.

In the present study, castor oil (CO) was modified by epoxidation, transesterification, and acrylation processes. In situ epoxidation method was used to prepare epoxidized castor oil (ECO) in acetic acid with hydrogen peroxide in the presence of Seralite SRC-120 catalyst. Transesterified epoxidized castor oil was synthesized from the reaction of methanol in the presence of sodium methoxide catalyst. The acrylated epoxidized castor oil was synthesized from the reaction of ECO with acrylic acid containing hydroquinone. Chemical structures of modified CO were analyzed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectra analysis.

In the current study, biobased polyurethane (PU) adhesives at three different stoichiometric ratios of hard (NCO) to soft segment (OH) (1.1:1, 1.3:1, 1.5:1) were prepared by reacting castor oil (CO) based polyol with partially biobased polyisocyanate (PBPI) in the presence of dibutyltin dilaurate (DBTDL) as catalyst. The synthesis of PU adhesive films such as CO-PU1.1:1, CO-PU1.3:1, and CO-PU1.5:1 was confirmed by Fourier transform infrared (FTIR) spectroscopy. The effect of stoichiometric ratios on the bonding strength of wood-to-wood substrate was studied using lap shear strength test. The change in lap shear strength of PU adhesive films subjected to acid and alkali solution was tested. The chemical resistance, surface properties and wetting energies of PU adhesive films were evaluated using scanning electron microscopy (SEM) analysis and contact angle measurement. Thermal stability and activation energy of the films were determined employing thermogravimetric analysis (TGA). The experimental result showed that CO-PU1.3:1 exhibited higher adhesive strength, where as CO-PU1.5:1 exhibited higher thermal stability.

The present study represents the synthesis of flexible polyurethane nanocomposite foam using Cloisite 30B nanoclays varying at 1, 2, and 3 wt%. The polyurethane nanocomposite foam formulated with 50:50 weight ratio of synthetic polyether polyol and renewable resource-based castor oil. The progress of isocyanate reaction and formation of bidentate urea through H-bonding in the polymeric matrix phase were confirmed from Fourier transform infrared analysis. The surface morphology of the nanocomposite foams was examined by scanning electron microscopy and X-ray diffraction analysis. Polyurethane nanocomposite foam displayed exfoliated structures at 3 wt% Cloisite 30B. The thermal and mechanical properties were also studied to report the impact of Cloisite 30B in biobased flexible polyurethane foam. Enhanced thermogravimetric outcome signified higher thermal stability of polyurethane nanocomposite foam as compared to polyurethane foam. Further, improvement of the soft segment glass transition temperature (Tg) confirmed the role of Cloisite 30B in the phase separation behavior between the hard segment and soft segment in nanocomposite foams. A significant enhancement in the mechanical strength with incorporation of a small amount of Cloisite 30B nanoclay to the flexible polyurethane foam allows it for various low cost applications.

In the present study, the synergistic effect of hybrid boron nitride (BN) with graphene on the thermal conductivity of epoxy adhesives has been reported. Graphene was prepared by chemical reduction of graphite oxide (GO) in a mixture of concentrated H2SO4/H3PO4 acid. The particle size distribution of GO was found to be ~10 μm and a low contact angle of 54° with water indicated a hydrophilic surface. The structure of prepared graphene was characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy and atomic force microscopy (AFM). The thermal conductivity of adhesives was measured using guarded hot plate technique. Test results indicated an improvement in the thermal conductivity up to 1.65 W/mK, which was about ninefold increase over pristine epoxy. Mechanical properties of different epoxy formulations were also measured employing lap shear test. The surface characterization of different epoxy adhesive systems was characterized through XRD, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies. Fourier transform infrared also served to determine the nature of interactions between filler particles and epoxy resin. Non-isothermal differential scanning calorimetric (DSC) technique was used to investigate the effects of graphene and BN particles on the cure kinetics and cross-linking reaction of epoxy cured with amine curing agent. The Kissinger equation, the model-free isoconversional Flynn–Wall–Ozawa method and the Ozawa model were used to analyze the kinetic parameter. Copyright © 2017 John Wiley & Sons, Ltd.

In this work, a novel bio-renewable castor oil (CO) based aqueous polyurethane (PU) anionic prepolymer dispersion was prepared successfully using isophorone diisocyanate (IPDI) and dimethylol propionic acid (DMPA) as internal emulsifier maintaining NCO/OH molar ratios of 1:3 and 1:5, respectively. The intermolecular H-bonding change, type and intensity of the obtained films with change in molar ratio were investigated by analyzing with Fourier transform-infrared (FT-IR). The morphology of the films was recorded with scanning electron microscopy (SEM) and transmittance electron microscopy (TEM). The coating properties for the film were also studied and discussed. The structure-property relationship with different molar ratios of prepolymer revealed an increasing pattern showing increase in the hard segment content increases the physico-mechanical properties of the CO based PU prepolymer. The FT-IR deconvolution results are in agreement with the film properties. The excellent abrasion resistance properties of CO based films agree well with the surface morphology and FT-IR results. The outcome of the study also suggests use of CO as a better alternative to replace petroleum based polyol for feature perspective.

In the present study, in-situ epoxidation was employed to prepare epoxidized castor oil (ECO). Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectra analysis were used to analyze the chemical structures of ECO. Biobased epoxy blends were synthesized from diglycidyl ether of bisphenol A (DGEBA) and ECO at variable wt% using triethylenetetramine as curing agent. The thermal, mechanical and morphological behavior of blends has been investigated. The morphological study showed homogeneous mixing of the ECO and DGEBA blends. The blend prepared using 20 wt% of ECO showed optimum impact and flexural strength as compared with commercially available epoxy resin. The fracture toughness parameters, critical stress intensity (K IC ) and the critical strain of blends were also observed to increase as compared with the virgin matrix which revealed enhancement in toughness. The tensile property of the blend reduced with the increasing ECO content which confirmed the fact that the addition of the high amount of ECO reduces the crosslink density of the biobased epoxy.

In the present investigation, biobased films were derived from epoxidized soybean oil (ESO) and waterborne epoxy acrylate (WBEA) using Pripol-1009 as a bioderived crosslinker. Flory–Rehner equation was used for determining the crosslink density of the films. Biodegradability of these films has been studied by compost soil burial exposure test for 90 days. The change in surface morphology was studied using SEM and the weight loss with respect to exposure period was also assessed. The mechanistic study of the degradation process was analyzed through fourier transform infra red spectroscopic (FTIR) analysis. It was observed that the weight loss and morphology changes of ESO was governed by the material’s composition, crosslink density and the compost-burial exposure time. It was also suggested that Bacillus sp., Aspergillus sp., Mucous sp., and Pencillium sp. are the possible soil microbes that are involved in degradation of ESO in the compost soil environment more readily than WBEA counterpart. The ecotoxicity of the compost after biodegradation of the samples was assessed through seed germination and plant growth technique.

Castor oil has gained momentous attention as a valuable bio-based monomer and a potential alternative to the current petrobased polyol for synthesizing polyurethane due to the presence of inherent hydroxyl group. In spite of its huge potentiality very little has been reviewed regarding the development of polyurethane from castor oil. This review thus highlights the recent trends and development in the field of polyurethane and its nanocomposite based on castor oil including its biodegradability and weatherability studies. Further, this review also provides an insight regarding the utilization of castor oil based polyurethane and its nanocomposite for coating application.

This study focuses on synthesis of waterborne epoxy (WBE) derived from epoxidized soybean oil (ESO) and its compatibility with water-dispersible curing agent Pripol 1009, which is a bioderived long-chain dimer acid. The reaction parameters involved in the synthesis of WBE from ESO have been optimized based on physicochemical properties like hydroxyl value, epoxy equivalent value and degree of solubility of WBE. The WBE obtained after 5 and 6 h of reaction time was found to be of optimum composition with balanced physicochemical properties. The mechanical, thermal and physicochemical properties of WBE obtained after 6 h of reaction time revealed relatively better performance characteristics as compared to ESO.

In the present study, waterborne epoxy (WBE) was prepared and the parameters involved in the synthesis of WBE have been optimized based on physicochemical analysis. A dextrin-based curing agent (DCA) was synthesized from dextrin and trimellitic anhydride at variable molar ratios, reaction temperature, reaction duration, and solvent. Furthermore, the optimized composition of DCA and WBE system was used as adhesive in wood bonding. A comparative analysis of DCA-cured-bonded system was studied with phenol-formaldehyde (PF)-bonded adhesive system. From all the analyses, the performance characteristic WBE–DCA adhesive system was found comparable with that of PF-bonded system.

This research was accomplished to examine the mechanical, morphological and crystallization kinetics study of polyethylene/silver nanoparticles (Ag-NPs) nanocomposite films. In this research, low-density polyethylene (LDPE) nanocomposite films were prepared containing Ag-NPs using maleic-anhydride-grafted low-density polyethylene (LDPE-g-MAH) as a compatibilizer by the melt mixing process. From mechanical property evaluation, it is revealed that the LDPE/LDPE-g-MAH/Ag-NPs nanocomposite films showed decreased tensile strength as compared with virgin LDPE matrix. Thermal characteristics of the prepared virgin LDPE and its nanocomposite films were studied by differential scanning calorimetry (DSC). Comprehensive analysis of different kinetic models such as the Avrami and Mo model on non-isothermal crystallization kinetics was performed in order to correlate the rate of crystallization and its various kinetic parameters. Further, the macrokinetic equation as proposed by Malkin has been applied to describe the kinetics of crystallization in the light of the Avrami equation. Concerning virgin LDPE and Ag-NP-reinforced LDPE, the former shows primary crystallization, whereas the later exhibits both primary and secondary crystallization with varying Avrami exponents. Kinetic parameters are recognized, and confirm the influence of Ag-NPs on crystallization kinetics. X-ray diffraction spectroscopy and transmission electron microscopic analysis of the nanocomposite films were conducted to verify the dispersion of inorganic filler particles in the resulting hybrids.

In this work, an effort has been made to develop a new type of complex conductive adhesive filled with silver decorated multi-walled carbon nanotubes (Ag-MWCNT). MWCNTs have been modified using N,N-dimethyl formamide (DMF) as a reducing agent and silver nanoparticles (Ag-NPs) has been homogeneously decorated against the surface. Fourier transform infra-red spectroscopy (FTIR) and Raman spectroscopy concluded that carboxylic groups were anchored to the surface of nanotubes. X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS) confirmed that Ag-NPs were formed and uniformly deposited onto the surface of carboxylic functionalized MWCNT. Test results indicated an improvement in the thermal conductivity up to 0.88 W/mK, which was about four-fold increase over pristine epoxy. The curing kinetics of Ag-MWCNTs reinforced epoxy adhesive system was also studied using non-isothermal differential scanning calorimetric (DSC) technique. The activation energy obtained by Kissinger’s method was reduced from 57.2 to 54 kJ/mol with an addition of 0.5 wt% of Ag-MWCNT within unmodified epoxy. Lap shear strength of the adhesive containing 0.5 wt% of Ag-MWCNT was higher than the pristine polymer thus confirming reinforcing effect of Ag-MWCNT in conductivity applications.

A phenalkamine made from the reaction of alkyl phenol from cashew nut shell liquid (CNSL) and alkaylamine was added at three different weight percentages (30%, 40%, and 50%) as a hardener for curing the epoxy polymer. The effect of phenalkamine concentrtation on mechanical and dry sliding wear resistance properties were compared to synthetic aliphatic amine (TETA) cured epoxy network. It was obsererved that incorporation of phenalkamine improves the dry sliding wear resistance property of the epoxy network along with the impact strength and elongation properties. Epoxy composites incorporating sisal fiber placed unidirectionally (either parallel, anti-parallel, or perpendicular to the sliding direction) were prepared in a vacuum infusion process using phenalkamine as a crosslinking agent. It was observered that wear resistance of longitudinally oriented fibers composite was found to be higher owing to the area of fibers exposed to sliding asperities being smaller. With the goal to understand the b...

The current study aims to investigate the influence of UV aging on the properties of green polyurethane (MBPU) and polyurethane/nanosilica composite (MBPU/NS) coatings synthesized from transesterified castor oil and palm oil isocyanate for an exposure period of 1250 h. Changes in the mechanical properties, structural features, morphological and coating properties have been monitored at every 250 h by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and colorimetry etc. MBPU/NS with 2.5 wt% of NS has been considered to be the optimum composition for a comparative UV aging analysis against neat MBPU. FTIR and XPS analysis revealed changes in chemical structure of MBPU and MBPU/NS-2.5 composite with reduction in –NHCO, C–C, C=O group concentrations. SEM and AFM micrographs indicated increase in roughness parameter with appearance of blisters and cracks on the exposed surface. Mechanical test results showed that UV aging decreases the tensile strength and elongation at break due to chain scission. The yellowness index (ΔYI) follows a systematic increasing trend with increment in irradiation time which indicates photodegradation of polyurethane. However, MBPU/NS-2.5 exhibited lower photo-oxidative degradation which can be due to its high UV absorption ability.

This paper aims to assess the biodegradability of neat polyurethane and polyurethane/nanosilica composite based on transesterified castor oil and isocyanate derived from palm oil under composting condition for an exposure period of 90 days. Fungal and bacterial colonies have been isolated and identified from the surface of the degraded sample. The biodegradation of the films have been investigated in terms of change in structural, morphological, weight loss and thermal properties. The FTIR results indicated noticeable changes between the spectra of unexposed and exposed samples, with respect to decrease in the intensity of absorption bands corresponding to ester and urethane linkages suggesting the occurrence of biodegradation. The biodegradation has been also confirmed using SEM studies through the appearance of corrosive structures, cracks and surface pitting. However, faster rate of degradation has been observed in case of polyurethane/nanosilica composite owing to its surface hydrophobicity, lower crystallinity and presence of surface hydroxyl groups that facilitates attack of microorganisms.

The present research is based on a comparative study of anhydride cured biobased and petroleum-based epoxy network. The effect of epoxidized soybean oil (ESO) bioresin on petroleum-based epoxy (DGEBA) at varying compositions cured with methylhexahydrophthalic anhydride (MHHPA) as curing agent and 2-methyl imidazole (2-MI) as the catalyst has been investigated. The tensile strength of virgin epoxy (42.94 MPa) increased to 48.62 MPa with the addition of 20% of ESO. The fracture toughness parameters; critical stress intensity factor (KIC) and critical strain energy release rate revealed enhancement of toughness in the biobased blends. Differential scanning calorimetry studies confirmed an enhancement in the peak temperature and a reduction in the heat of curing in virgin epoxy on incorporation of ESO content. The thermomechanical and fracture morphological properties of virgin epoxy, ESO, and its biobased blends were investigated by thermogravimetric analysis, dynamic mechanical analysis, atomic force micros...

Waterborne polyurethane dispersions (WPUDs) were synthesized successfully from castor oil-based polyol, isophorone diisocyanate and dimethylol propionic acid with NCO/OH ratio of 1.5. Different weight percentages of cloisite 30B (1, 2, and 3 wt%) were loaded with WPUDs to prepare nanocomposite films. Prepared prepolymer and nanocomposite films were characterized using FTIR, XRD, SEM, TEM, DSC, and TGA techniques, and coating properties, such as pencil hardness, abrasion resistance, impact resistance, and contact angle, were evaluated. The results obtained from different amounts of clay loading were compared with the pristine castor oil-based WPUDs. The FTIR spectra deconvolution technique was used to study the hydrogen bonding effect within the polymer with an increase in clay content. TGA analysis showed that the thermal stability of WPUDs increases with cloisite 30B (C30B) content. The surface morphology and hydrophilicity/hydrophobicity nature of the nanocomposite films were characterized using scanning electron microscopy and contact angle measurement. The results obtained from tensile tests indicated that the mechanical property of the dispersion system improved with C30B content. A high-performance castor oil-based nanocomposite coating with low volatile organic component can be targeted as an outcome of this work.

We report the growth of a Mg incorporated GaN nanowall network (NwN) by using a plasma assisted molecular beam epitaxy (PA-MBE) system that was characterized by photoluminescence (PL) spectroscopy, Raman spectroscopy, high-resolution X-ray diffraction (HR-XRD), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). We record a PL enhancement (≈3.2 times) in nominally and moderately Mg incorporated GaN compared to that of an undoped NwN. Two distinct (and broad) blue luminescence peaks appear at 2.95 and 2.70 eV for the heavily Mg incorporated (1020 atoms per cm3) GaN, of which the 2.95 eV peak is sensitive to annealing. The incorporated Mg concentration is estimated to be 1020 atoms per cm3 while retaining its band edge emission at ≈3.4 eV. XPS valence band spectra shows a shift in the Fermi level towards Valence Band Maximum (VBM) and the increase in Mg flux confirms the formation of p-type GaN. Mg accumulation at the nanowall surface and the GaN/Al2O3 interface was observed from SIMS measurements.

Intentional doping and unintentional impurities in intrinsic semiconductors generate carriers that enable device operations. Fundamental to the electronic activity of dopants and impurities is the introduction of defect states inside the forbidden energy gap of semiconductors having shallow and/or deep characteristics, which fundamentally define the ability to engineer its physical properties and associated device performance. Here we demonstrate that unintentional electron doping by oxygen (${\mathrm{O}}_{\mathrm{N}}$) impurities and intentional magnesium hole doping ($\mathrm{M}{\mathrm{g}}_{\mathrm{Sc}}$) in scandium nitride (ScN) do not introduce any defect states inside its fundamental bandgap and that the rigid-band electronic structure remains unchanged. Employing a combination of spectroscopic techniques as well as first-principles density functional theory analysis, we show that the ${\mathrm{O}}_{\mathrm{N}}$ and $\mathrm{M}{\mathrm{g}}_{\mathrm{Sc}}$ defect states in ScN are located inside the bands, which leaves behind the virgin ScN bandgap as well as the valence and conduction band edges that are important for electronic transport. The rigid-band electronic structure of ScN with respect to the electron and hole doping results in high electron and hole concentrations due to the free movement of Fermi level and results in tunable electronic and thermoelectric properties necessary for device applications.

Extreme complexity in the range of metallic and non-metallic parts present in waste printed circuit boards leads to incineration for collecting valuable metals. The non-metallic parts of the printed circuit board can be used effectively without affecting the environment. In this study, the non-metallic parts of the printed circuit board, which is made up by cross-linked resin and fibre, was used as a filler in recycled plasticised polyvinyl chloride collected from waste wires and cables. The properties of the plasticised polyvinyl chloride matrix and plasticised polyvinyl chloride–non-metallic parts of printed circuit board composite were compared with each other by means of mechanical properties and thermal properties. Both mechanical and thermal properties results indicated that incorporation of non-metallic parts of printed circuit board significantly improved the hardness, stiffness, abrasion resistance and thermal stability of plasticised polyvinyl chloride–non-metallic parts of printed circuit board composite; however, the tensile strength of the composite material is not improved because of poor adhesion between the plasticised polyvinyl chloride matrix and non-metallic parts of printed circuit board filler. The poor chemical interaction is also observed from Fourier transform infrared spectroscopy results. This plasticised polyvinyl chloride–non-metallic parts of printed circuit board composite can reduce the leaching of a hazardous element from the printed circuit board with effective utilisation of plastics fraction from waste wires and cables.

In recent years, significant interest has been focused on fabricating epoxy-based hybrid composite with a high thermal conductivity at optimum filler loading. As epoxy usually has a low thermal conductivity, the high intrinsic thermal conducting fillers such as h-BN, GO and RGO are incorporated. In this research, we report the epoxy-based hybrid composites with an enhanced thermal conductivity through silane-modified h-BN (mh-BN) with RGO. The sample containing 44.5 wt% (40 wt% mh-BN and 4.5 wt% RGO) hybrid filler exhibited the highest thermal conductivity (1.416 W/mK) which was 7 times that of pristine epoxy (0.21 W/mK). The thermal conductivities of RGO with unmodified h-BN (0.789 W/mK), GO with mh-BN (0.769 W/mK) and GO with unmodified h-BN (0.713) at 44.5 wt% loading are also reported. Comparison property studies of these above-mentioned four hybrid composites are described by lap shear strength, flexural strength, impact strength and thermogravimetric analysis. The fabricated hybrid composites exhibit outstanding performance in lap shear strength, thermal stability, and slightly reduced impact and flexural strength, which makes it as relevant for electronics packaging application such semiconductors, integrated circuit packaging, optoelectronics and also can attest potentiality in structural energy storage application. The atomic force microscopy and scanning electron microscopy verified the surface roughness and morphology of two optimized compositions, i.e., mh-BN with RGO and h-BN with RGO with the epoxy matrix. Also, Maxwell, Hashin–Shtrikmann and series equations are used to verify the obtained experimental value.

Reinforced epoxy composite adhesives of expanded graphite (EG) and graphene nanoplatelet (GNPs) were prepared by hand layup and mechanical mixing method. Disk-shaped epoxy composite samples with EG and GNP mixtures in varying ratios were prepared to measure the thermal conductivity (TC) enhancement. Thermal characterization testing data showed high thermal conductivity enhancement with three different hybrid filler concentrations of 10, 25, and 35 wt%, respectively. The highest thermal conductivity of 3.6 W/m K was obtained for an epoxy adhesive composite having 30 wt.% EG and 5 wt.% GNP which was tested by guarded heat flow meter technique. This significant improvement in thermal conductivity can be attributed to the lowering of overall thermal interface resistance due to small amounts of nanofiller (GNP) improving the thermal contact between the primary microfillers (graphite). The synergistic effect of this hybrid filler system is lost at higher loadings of the GNP relative to expanded graphite. The structure of the graphite flake, GNP/epoxy, EG/epoxy and hybrid EG/GNP/epoxy composites was investigated by XRD. The EG prepared by acid intercalation and abrupt thermal expansion showed good compatibility with GNP and the epoxy resin. From scanning electron microscopy photographs, the formation of conducting network observed through the expanded graphite and GNPs in a low conducting epoxy matrix. The thermal decomposition temperature of the composite increased to 450 and 615 °C with the addition of 10 and 35 wt% of hybrid EG/GNP inside epoxy matrix, respectively. LAP shear strength of single and hybrid filled epoxy adhesive decreased at 35 wt.% loading than neat epoxy.

Polyurethane (PUs) is gaining immense interest as a speciality polymer for various high-end applications. Vegetable oil has gained momentous attention as a valuable renewable precursor and a potential alternative to the current petro-based polyol for the synthesis of PUs. The concept of reinforcing nanofiller into vegetable oil-based PU matrix has gained huge research interest for the development of bio-based PU nanocomposites with tailor-made properties. The addition of nanofiller into bio-based PU nanocomposites has led to the improvement of thermal, mechanical, optical and physicochemical properties. This chapter will deal with the detailed insight regarding the synthesis, characterization of bio-based PUs nanocomposites from various vegetable oil incorporated with different nanofillers.

The scaffold is a three-dimensional (3D) substrate that works as a pattern for revival of the tissue. The tissue-engineered products comprise heart valves, cartilages, bones, muscle, nerves, liver, bladder, etc. The scaffold provides the necessary provision for the cells to attach, multiply, and sustain their distinguished functions. In recent years, polymeric scaffolds play a significant role in the tissue engineering application. A wide range of natural and synthetic biopolymers are being used for the fabrication of the scaffolds, which includes proteins, chitosan, polysaccharides, poly(lactic acid) (PLA), poly(glycolic acid) (PGA), poly (e-caprolactone) (PCL), poly(lactic-co-glycolic) acid (PLGA), etc. In addition bioactive glass and ceramic particles are reinforced with biopolymers and are used in the form of biocomposites for fabricating scaffolds structures. The reinforced biopolymers are extensively used in the development of scaffolds, due to incredible properties such as mechanical strength, regulated pore size, biodegradability, biocompatibility, and renewability. The fabricating materials are opted based on the functionality of the scaffolds, i.e., either synthetic or biologic, in other way degradable or nondegradable. The scaffolds are also distinguished based on the specific period of performance; commonly they are classified as short-term and long-term scaffolds. They are either injectable or implantable; usually the short-term scaffolds are injected and are biodegradable, whereas the long-term scaffolds are implanted and may be degradable or nondegradable. Various fabrication techniques were being adapted by the researchers to develop the scaffolds, which includes solvent casting, particulate leaching, phase separation, electrospinning, gas foaming, freeze-drying, and rapid prototyping. The selection of the materials and manufacturing methodologies are critically important for tissue engineering in designing the artificially made extracellular matrices (scaffolds), which can provide the support for three-dimensional tissue formation. Furthermore, various post-process surface modification methods are performed on the scaffolds to improve their functional performance.

Fe doped ZnO nanoparticles were prepared by co-precipitation method and characterized with XRD and UV-VIS spectroscopy. These nanoparticles with PVDF-TrFE used for composite film preparation via solvent casting method. XRD of these films were taken into accountto analyse the β-phase of the films. It is observed that the increment in the filler percentage increases the intensity at 2Ө=20° confirming the β-phase orientation of the film.

The increased use of unsaturated polyester resin (UPR) and their composites are raising demands on proper disposal and recycling of their end-of-life products. Until recently, landfills were used to dispose of the scrap from UPR and composites. But raising environmental concerns demand the need to implement effective recycling strategies to depolymerize the resin based composites. Recycling techniques such as mechanical, thermal, and chemical pathways can be used to depolymerize and recover the composites’ constituents. This chapter gives insight into the various recycling techniques that are being used to recycle UPR and their composites and some of the recent advancements in this field.

This paper first time reports the preparation of random anionic copolymers from vinyl acetate (VAc) bearing electro-donating substituent and sodium 4-vinylbenzenesulfonate (SSA) having electro-withdrawing substituent. Copolymers (PVA-co-SSA) of different composition have been successfully prepared by a simple free radical solution polymerization technique. Resulting final copolymer contained neutral hydrophilic as well as ionizable ion exchange sites. Evaluation of spectral data obtained from Fourier transform Infrared spectroscopy, Raman spectroscopy, and 1H Nuclear magnetic resonance helped in identifying and confirming the chemical structure of copolymers. Characterization of copolymers by gel permeation chromatography revealed high molecular weight with moderate polydispersity index. Analysis of thermal stability and glass transition temperature of copolymers by thermogravimetric analysis and differential scanning calorimetry were found in between corresponding homopolymers. Physicochemical properties of PVA-co-SSA can be beneficial for prospective advanced application in the niche area of smart membrane technology for energy and environment.

Light Emitting Polymers (LEPs) have gained attention in optoelectronics. However, stability and regulation of emission color remain a challenge. This study aims to overcome the challenge by formulating a Polymer Blend (PB) which consists of a LEP – poly [2-methoxy,5-(2-ethylhexyloxy)1,4-phynylenevinylene (MEH-PPV) and a non-conjugated polymer – poly(methyl methacrylate) (PMMA). A simple approach of in situ polymerization of the non-conjugated polymer in the MEH-PPV solution leads to alteration of size of the MEH-PPV polymer chain and modified the emission color from red-orange to bluish-green. The barrier properties of PMMA improve the stability of PB in an ambient environment with unnoticeable luminescence loss. This type of PB shall find application in Organic Light-Emitting Devices.

Implementation of green energy storage system via integrating natural materials has become an indispensable requirement for a sustainable future. In this study, polyaniline (PANI) and multiwalled carbon nanotubes (MWCNT) filled flexible porous mixed matrix membrane (MMM) were developed from chitosan (CS) and cellulose acetate (CA) for supercapacitor applications. The results reflect that the unique membrane morphology of the MMM electrode aid for the better areal capacitance of 30.69 mF/cm2 at a scan rate of 25 mV/s when compared with CA/CS (CC) paper based electrode having same compositions of PANI and MWCNT (15.71 mF/cm2 at a scan rate of 25 mV/s). The present strategy paved way to biopolymer based mixed matrix membrane (MMM) having facile fabrication, high porosity and flexibility as sustainable electrode materials for energy storage applications.

In this study, we attempted to prepare a binary polymer blend of poly (vinylidene fluoride) (PVDF) and poly lactic acid (PLA) by employing solvent casting method. Both PVDF and PLA possessing good piezoelectric properties, are considered for energy storage and energy harvesting applications. PVDF-PLA blends were uniaxially stretched at stretch ratios 1–3 to modify the structural and dielectric properties. Spectroscopic studies such as; Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the improvement in electroactive polar phases of PVDF thus revealing the successful intermolecular interaction between CH2 and CF2 group of PVDF and -C = O or −OH or −CH3 group of PLA leading to good compatibility between both the polymers. Impedance specroscopy measurement confirmed the enhanced dielctric behaviour of unstretched (e’ = 10.5 and tan δ = 0.001) as well as mechanically stretched blend (e’ = 14.4 and tan δ = 0.001) which is ascribed to the formation of smaller spherulites at their interface which eventually facilitated their interfacial polarisation.

Point defects create exotic properties in materials such as defect-induced luminescence in wide-bandgap semiconductors, magnetism in nonmagnetic materials, single-photon emission from semiconductors, etc. In this article, oxygen defect formation in metallic TiN and semiconducting rock salt-(Al,Sc)N is investigated with a combination of first-principles density functional theory, synchrotron-based x-ray absorption spectroscopy (XAS) analysis, and scanning transmission electron microscopy–energy-dispersive x-ray spectroscopy mapping. Modeling results show that oxygen in TiN and rock salt-(Al,Sc)N prefers to be in the defect complex of substitutional and interstitial oxygen (nON + Oi) types. While in TiN, the preferential interstitial sites of oxygen in ON + Oi are at the tetrahedral site, in rock salt-(Al,Sc)N, a split interstitial site along the [111] direction was found to be energetically preferable. Simulations performed as a function of the oxygen partial pressure show that under experimental growth conditions, four oxygen atoms at the substitutional sites of nitrogen (4ON), along with four Ti atoms, decorate around an interstitial oxygen atom at the tetrahedral site (Oi) in the energetically favored configuration. However, in rock salt-(Al,Sc)N, n in nON + Oi was found to vary from two to four depending on the oxygen partial pressure. Theoretical predictions agree well with the experimentally obtained XAS results. These results are not only important for a fundamental understanding of oxygen impurity defect behavior in rock salt nitride materials but will also help in the development of epitaxial metal/semiconductor superlattices with efficient thermionic properties.

The present study deals with the fabrication of nanocomposite membrane by incorporation of modified (3-aminopropyl)triethoxysilane treated silicon oxide (APTES-SiO2) within poly(vinylidene fluoride) (PVDF) matrix. Further, this nanocomposite membrane was treated with chlorosulfonic acid in order to incorporate the hydrophilic sulfonated (-SO3H) group within the membrane structure. The successful incorporation of nanoparticles within the host polymer structure as well as the sulfonation of the nanocomposite membranes were confirmed from FTIR, NMR and XPS studies respectively. The enhanced ion exchange capacity (0.6 meq g−1) and proton conductivity (9.4 × 10−2 S cm−1) indicate the potentiality of the membranes in fuel cell applications. Further, the greater conductivities of the membranes at high temperature indicates their suitability for performing at high temperature surroundings. The membranes displayed suppressed methanol crossover (50.21% lower as compared to Nafion) leading to more than one-fold higher membrane selectivity thus signifying a potential alternative to Nafion for fuel cell applications.

Hybrid organic–inorganic nanocomposites employ metal oxides to improve the charge transport properties and stability of the conjugated polymer. They are considered one of the most interesting candidates for optoelectronic applications. This article presents a detailed investigation on the influence of defective electronic states of MgO nanoparticles on the photophysical properties and photostability of a conjugated polymer, poly[2-methoxy-5-(2-ethylhyxyloxy)-1,4-phenylene vinylene] (MEH-PPV). Since MgO is an insulator (Eg – 7.8 eV), defect states were induced to improve the delocalization of electrons and conductivity. These defect-induced MgO nanoparticles accounted for the enhanced absorbance in the hybrid polymer nanocomposites. The nanocomposites demonstrated photoluminescence (PL) quenching owing to the transfer of electrons from MEH-PPV to the defective energy levels (oxygen vacancies) of MgO. The photoinduced electron transfer was confirmed through solvent and temperature-dependent PL analysis, and also through electrochemical analysis. The MEH-PPV/MgO nanocomposite displayed 23% PL quantum efficiency. An improvement in photostability was observed due to the reduction in the polymer chain defects, prevention of oxygen diffusion by MgO nanoparticles, inhibition of moisture intervention by improving the hydrophobicity of nanocomposites, and most importantly, transfer of electrons from the polymer to oxygen vacancies, which prohibited superoxide formation. Hence, this work validates the role of oxygen vacancies of MgO nanoparticles in the PL quenching and photostability enhancement of MEH-PPV.

We determine atomic structure, electronic structure, formation energies, magnetic properties of native point defects, such as gallium (Ga) and nitrogen (N) vacancies, in bulk and at the nonpolar (10 1 ¯0) surface of wurtzite gallium nitride (w-GaN) using first-principles density functional theory (DFT) based calculations. In bulk and at the (10 1 ¯ 0) surface of GaN, N vacancies are significantly more stable than Ga vacancies under both Ga-rich and N-rich conditions. We show that within DFT-local density approximated N vacancies form spontaneously at the (10 1 ¯ 0) surface of GaN when doped to raise the Fermi level up to ≈ 1.0 eV above valence band maximum (VBM) while with valence band edge correction it is 1.79 eV above VBM. We provide experimental evidence for occurrence of N vacancies with electron energy loss spectroscopy measurements, which further hints the N vacancies at surface to the source of auto-doping which may explain high electrical conductivity of GaN nanowall network grown with molecular beam epitaxy.

The current study focuses on the effective sulfonation of polyethersulfone (PES) polymer to synthesize sulfonated-polyethersulfone (SPES) and blending with PES to prepare SPES/PES blend membranes as well as preparation of cellulose acetate CA/PES blend membranes. FTIR-ATR technique was used to confirm the blending of SPES and CA into PES matrix. Water contact angle studies showed a significant reduction of hydrophobicity in SPES blend membranes (49.55 ± 1.52°) as compared with CA blend membranes (59.42 ± 2.20°) and PES base membranes (67.80 ± 1.48°). The presence of pores were analysed using scanning electron microscopy (SEM) where significant changes in the membrane morphology in the blend membranes were observed. Platelet adhesion, protein adsorption and activated partial thromboplastin time (APTT) studies were used to assess hemocompatibility of the membranes in which SPES/PES membranes exhibited improved characteristics as compared with its counterparts. The cytocompatibility of membranes were evaluated using water soluble tetrazolium (WST) assay which confirmed that both SPES/PES and CA/PES blend membranes exhibit better cytocompatibility than base PES membrane

Here, we report on the successful fabrication of organic-inorganic composite films with poly (vinylidene fluoride) (PVDF) polymer and calcium doped zinc oxide (CaZ) and cadmium doped zinc oxide (CdZ) as two different nanofillers. The incorporation of these nanofillers resulted in increased crystalline and piezoelectric β-phase content of PVDF composites. The comparison of temperature-dependent dielectric studies showed enhanced dielectric properties of CaZ-loaded PVDF composites compared to CdZ-based PVDF composites. At 1 kHz, a maximum dielectric permittivity of 26.13 with a dielectric loss of 0.477 was obtained for 10 wt% CaZ-loaded PVDF composite film (10 CaZ-P) at 100 °C. The relaxation time of as-prepared composites showed Arrhenius behavior and lower activation energy for 10 CaZ-P composites (66.24 kJ/mol). For the 10 CaZ-P composite films, the AFM topography analysis showed higher roughness value (16.54 nm) and confirmed the lower activation energy of the same.