Search

The mushrooming utilization of electronic devices in the current era produces electromagnetic interference (EMI) capable of disabling commercial and military electronic appliances on a level like never before. Due to this, the development of advanced materials for effectively shielding electromagnetic radiation has now become a pressing priority for the scientific world. This paper reviews the current research status of polymer nanocomposite-based EMI shielding materials, with a special focus on those with hybrid fillers and MXenes. A discussion on the theory of EMI shielding followed by a brief account of the most popular synthesis methods of EMI shielding polymer nanocomposites is included in this review. Emphasis is given to unravelling the connection between microstructures of the composites, their physical properties, filler type, and EMI shielding efficiency (EMI SE). Along with EMI shielding efficiency and conductivity, mechanical properties reported for EMI shielding polymer nanocomposites are also reviewed. An elaborate discussion on the gap areas in various fields where EMI shielding materials have potential applications is reported, and future directions of research are proposed to overcome the existing technological obstacles.

This work investigates the dynamic mechanical properties (DMA) and ageing behavior of coir-sisal yarn reinforced polypropylene commingled composites. Moreover, the fibres were subjected to various chemical treatments and their effects on DMA and ageing studies were investigated. DMA reveals that the chemical treatment, especially MAPP treatment, enhances the storage and loss modulus values on the other hand it diminishes the mechanical damping coefficient (tan δ) of the composite. Diffusion studies indicates that treated composites shows a much lower apparent percentage weight gain compared to other treated ones. Solar ageing studies shows that accelerated solar ageing deteriorated tensile strength and modulus of PP/coir-sisal yarn composite.

Inorganic-organic composites have significant importance in various fields including self cleaning displays, photocatalysis, solar energy conversion etc. The synthesis of polymer capped inorganic f ...

Despite the fact that metal oxides have gained a foothold into a range of structural applications over the last decade, their investigation in the field of sensors, supercapacitors, has been limited. Novel sol-gel derived TiO2-ZrO2 composite coatings have recently found lots of applications in industrial as well as scientific world. The present article reviews, scrutinizes and highlights various types of applications of TiO2-ZrO2 coatings, functioning mechanisms and synthesis techniques used globally. Herein, particular emphasis is firstly given to the challenges faced by metal oxides in their performance for different applications. The different synthesis methods for the metal oxide composites and deposition techniques for obtaining corresponding coatings were examined in-depth from the aspects of its merits and demerits. Their distinct characteristics, underlying mechanisms, and possible applications in a variety of fields are highlighted. The literature work also enumerates studies of the surface property towards water and organic dirt may jointly conclude its self-cleaning nature. The review provides an up-to-date account on the different applications such as electrochemical storage, antibacterial effect and photocatalysis for TiO2-ZrO2 coatings. An insightful viewpoint for rational design of binary metal oxide TiO2-ZrO2 towards sensing and capacitance is also provided. The functionalities include better surface area and porosity which facilitates the charge transport and prevention of charge recombination of the synthesized TiO2-ZrO2 composite coatings are thoroughly reviewed. Finally, the prospective uses and future perspectives, along with their scaling capabilities and potential advances of these nanocomposite coatings are examined.

A thick coating of hierarchically porous double-templated TiO2–ZrO2–PMMA–PF127 with excellent self-cleaning properties and high transmittance has been developed for the first time on glass substrates using a simple dip-coating technique. Comparative studies of this sample with a thick and transparent coating of single-templated TiO2–ZrO2–PMMA have been performed to probe the origin of its exceptional properties. The formation of the composites, successful incorporation of the polymer into the matrix, and the porous nature of the films have been studied. The presence of Ti2+ in the double-templated samples has been confirmed, which suggest the chemisorption of water on the surface of the film. The variation in the self-cleaning properties of the samples on UV-illumination has also been studied. The double-templated film is found to possess the capability of good hydrophilic retention even 2 days after UV-irradiation.

Carbon aerogels prepared from low-cost renewable resources are promising electrode materials for future energy storage applications. However, their electrochemical properties must be significantly improved to match the commercially used high-carbon petroleum products. This paper presents a facile method for the green synthesis of carbon aerogels (CAs) from lignocellulosic materials and graphene dots (GDs) from commercially available biochar. The produced carbon aerogels exhibited a hierarchical porous structure, which facilitates energy storage by forming an electrical double-layer capacitance. Surprisingly, the electrochemical analyses of the GD-doped carbon aerogels revealed that in comparison to pristine carbon aerogels, the surface doping of GDs enhanced the electrochemical performance of carbon aerogels, which can be attributed to the combined effect from both double-layer capacitance and pseudocapacitance. Herein, we designed and demonstrated the efficacy of a supercapacitor device using our green carbon electrode as a sustainable option. These green carbon aerogels have opened a window for their practical use in designing sustainable energy storage devices. Validerad;2021;Nivå 2;2021-11-30 (johcin)

Fibre reinforced polymer composite materials have been widely used in industries owing to their good strength, light weight nature and their remarkable mechanical properties. The increased use of synthetic fibre based composites have led to a large amount of composite waste being produced annually and that too globally and their management is becoming an important issue. The conservation of resources and environment is having a negative impact due to the current increasing amount and recycling of composite waste at their end of life cycle. This chapter focuses on the classification of various composites materials, recycling methods of fibre reinforced materials and their waste management.

Fiber reinforced materials were a quintessential ingredient in the manufacturing arena of humans since Stone Age. By dispersing the reinforcing fiber in a suitable matrix, novel functional materials could be developed. Carbon fibers and glass fibers are considered as important class of reinforcing fibers in polymer matrices owing to their high strength. Carbon fiber is five times stronger and two times stiffer than steel. Moreover, being a light weight material it is an ideal candidate for many high-end applications. Glass fiber has comparatively less stiffness than other reinforcing fibers, but it possesses the distinct advantage of having high specific strength and is cost effective. Glass fiber is a promising material to be used as a major reinforcement fiber because of its availability and ease of use. Elastomeric polymers are extensively used as matrices in polymer composites, because of their outstanding visco-elastic properties, flexibility and wide choice of fillers. This chapter gives an overview of the evolution, synthesis, mechanical, thermal and visco elastic characteristics of carbon fiber and glass fiber reinforced elastomeric composites coupled with their potential applications.

The present century has witnessed composite materials to be the most promising and shrewd material for a variety of applications. Among them fiber (natural or synthetic) reinforced composites (FRCs) have gained significant interest owing to the high demand for lightweight materials with high strength for specific applications. The advantages of FRCs include high strength to weight ratio, high durability and stiffness, good damping behavior, flexural strength and most importantly good resistance to corrosion, wear, impact and fire (depending on the matrix and fiber reinforcement). The presence of such wide array of properties for FRCs have led to them being used extensively in a number of applications including mechanical, aerospace, automotive, marine, sports, biomedical, construction etc. The past decades have visualized exciting research in the area of FRC's which helped to unveil the properties of these exciting materials further and consign them in appropriate applications. These FRCs have shown outstanding performance in different fields of applications and hence have been promoted by researchers as promising alternatives to solitary metals and alloys. The global demand for fiber reinforced composites is expected to grow at a faster pace with the aerospace industry occupying the top position in the years to come. Major driving factors for the rising demand is none other than the high strength to weight ratio, corrosion resistance, energy absorption on impact, moisture and chemical resistance possessed by these materials. This chapter gives a general overview on the characteristics and processing of FRC's that are systematically outlined in this book.

The chemical structure and ability to fine-tune its properties have made polysaccharide based composites a very attractive biomaterial. Polysaccharides are copious in nature and have good processability and hence have become one of the most commonly used biomaterial compared with other synthetic biomaterials. The biggest advantage of using polysaccharides in green composites is their environmental friendly nature. Among the different types of polysaccharides, carrageenan a sulfated polysaccharide extracted from red algae has recently received much attention. The applications of carrageenan-based materials include as gelling, stabilizing, and thickening agents in areas like food products. These materials have recently been explored in industrial applications, cosmetics, pharmaceutical applications, etc. Carrageenan-based materials are favorable alternative to fossil fuel-based polymers and are highly regarded as probable renewable and sustainable composite materials.

Electromagnetic shielding is presently considered very crucial for various electrical systems owing to the creation of electromagnetic pollution instigated by the alarming usage of electronic gadgets working at diverse frequencies and power levels. Conventionally used electromagnetic interference (EMI) metallic shields lack flexibility and hence cannot be considered as the right candidates for certain applications. This problem requires immediate attention because it causes drastic effects on the lifetime and performance of electronic devices and has an adverse effect on human beings as well. Rubber-based composite materials are regarded as suitable candidates for the fabrication of electromagnetic shields due to their combined electrical conductivity, interesting mechanical, and dielectric properties, elasticity to cover curved structures, and weather resistance for outdoor applications. This chapter aims to discuss the various fillers as well as elastomers used in the fabrication of elastomeric composites used in the preparation of EMI shielding devices. Finally a discussion of elastomeric blends used for shielding purpose will also be added.

This chapter outlines polymer/clay nanocomposites and its membrane transport characteristics especially pervaporation (PV) property. PV is a membrane-based process that combines permeation and vaporization and is used for separating two or multicomponent mixtures of various organic fluids through dense membranes. PV is a low energy process and it is very easy to operate. Influence of filler morphology and other parameters such as temperature, feed concentration, permeate pressure, etc. are important factors that may affect the effectiveness of membranes for PV process. Industrial applications such as desalination of sea-water and separation of organic liquid mixtures have benefited immensely from the membrane separation techniques.

The success of developing graphene based biomaterials depends on its ease of synthesis, use of environmentally benign methods and low toxicity of the chemicals involved as well as biocompatibility of the final products/devices. We report, herein, a simple, scalable and safe method to produce defect free few layers graphene using naturally available phenolics i.e. curcumin/tetrahydrocurcumin/quercetin, as solid-phase exfoliating agents with a productivity of ∼45 g/batch (D/G ≤ 0.54 and D/D′ ≤ 1.23). The production method can also be employed in liquid-phase using a ball mill (20 g/batch, D/G ≤ 0.23 and D/D′ ≤ 1.12) and a sand grinder (10 g/batch, D/G ≤ 0.11 and D/D∼ ≤ 0.78). The combined effect of π-π interaction and charge transfer (from curcumin to graphene) is postulated to be the driving force for efficient exfoliation of graphite. The yielded graphene was mixed with the natural rubber (NR) latex to produce thin film nanocomposites, which show superior tensile strength with low modulus and no loss of % elongation at break. In-vitro and in-vivo investigations demonstrate that the prepared nanocomposite is biocompatible. This approach could be useful for the production of materials suitable in products (gloves/condoms/catheters), which come in contact with body parts/body fluids.

The present work discloses the admirable electromagnetic interference shielding effectiveness (∼50 dB at X and Ku Bands) realized by means of excellent dispersion state of reduced graphene oxide (rGO) in a polypropylene (PP) matrix, even at high concentrations (20 wt%). This was achieved by means of a latex method (polymer matrix; here PP in the aqueous emulsion state) combined with in situ reduction of graphene oxide using L-ascorbic acid as the reducing agent (green approach). A probable reaction mechanism between the maleic acid anhydride part of the PP matrix with the remaining –OH groups of rGO which may further assist in the better dispersion of graphene is also suggested. The prepared PP/rGO nanocomposites showed a percolation threshold in between that of 1.5 and 3 wt% rGO content. The microcapacitor and the conductive pathway formation in the system are explained nicely with the help of a schematic diagram. The electromagnetic interference shielding effectiveness (EMI SE) of 50 and 48 dB achieved for the X and Ku-bands for the 20 wt% rGO filled sample is one of the best among current works based on GO as the filler. The thermal stability of the samples increased marginally due to the addition of thermally stable rGO. The crystallization temperature increased with increasing rGO content owing to its good nucleating ability, whereas the melting characteristics shifted from double to single melting behavior possibly due to the ability of rGO to explicitly nucleate a particular polymorph of PP. A simple, cost efficient, green and promising approach to prepare non-polar polymer/graphene nanocomposites with a good dispersion state of graphene and excellent properties is reported in the present work.

Present work describes in detail the preparation and characterization of zirconia (ZrO2) incorporated polyacrylonitrile (PAN) based carbon nanofiber reinforced epoxy composites as effective electromagnetic interference (EMI) shielding material. Zirconia incorporated PAN nanofiber mat was prepared by electrospinning process in N, N-dimethylformamide solvent medium. These nanofiber mats were thermally treated at 1000˚C to form zirconia incorporated carbon nanofiber mats (CNFs). These mats were impregnated with epoxy resin, and ZrO2 /CNF epoxy laminas were prepared. It was revealed that the storage modulus of ZrO 2@CNF/epoxy composites was superior to that of neat CNF/epoxy composites. The total electromagnetic interference (EMI) shielding effectiveness of carbonized mats and CNF/epoxy composites was analyzed, and excellent specific shielding was observed. Stacking these ZrO2@CNF mats proved to be an excellent tactic, and (8 layers) displayed an outstanding EMI shielding effectiveness of more than -90 dB in the Ku band, which is very significant for potential industrial, radar, and military applications.

The effect of pyrolysis reactors on the properties of biochars (with a focus on flammability and mechanical characteristics) were investigated by keeping factors such as feedstock, carbonisation temperature, heating rate and residence time constant. The reactors employed were hydrothermal, fixed-bed batch vertical and fixed-bed batch horizontal-tube reactors. The vertical and tube reactors, at the same temperature, produced biochars having comparable elemental carbon content, surface functionalities, thermal degradation pattern and peak heat release rates. The hydrothermal reactor, although, a low-temperature process, produced biochar with high fire resistance because the formed tarry volatiles sealed water inside the pores, which hindered combustion. However, the biochar from hydrothermal reactor had the lowest nanoindentation properties whereas the tube reactor-produced biochar at 300 °C had the highest nanoindentation-hardness (290 Megapascal) and modulus (ca. 4 Gigapascal) amongst the other tested samples. Based on the inherent flammability and mechanical properties of biochars, polymeric composites’ properties can be predicted that can include them as constituents.

Biocomposites being environmentally-friendly alternative to synthetic composites are gaining increasing demand for various applications. Hence, biocomposite development should be integrated within a circular economy (CE) model to ensure a sustainable production that is simultaneously innocuous towards the environment. This review presents an overview of the state-of-the-art technologies for the adoption of the CE concept in biocomposite development. The study outlined the properties, environmental and economic impacts of biocomposites. A critical review of the life-cycle assessment of biocomposite for evaluating greenhouse gas emissions and carbon footprints was conducted. In addition, the opportunities and challenges pertaining to the implementation of CE have been discussed in detail. Recycling and utilisation of bio-based constituents were identified as the critical factors in embracing CE. Therefore, the development of innovative recycling technologies and an enhanced use of novel biocomposite constituents could lead to a reduction in material waste and environmental footprints. This article is one of the first studies to review the circularity of biocomposites in detail that will stimulate further research in enhancing the sustainability of these polymeric materials.

Bidirectional PP/jute yarn eco-composites were fabricated via environment friendly commingling technique and its long term durability/life time was monitored as an effect of accelerated solar ageing on its mechanical properties (tensile & flexural). Accelerated solar ageing promoted the thermal oxidation of PP thus resulting in deterioration of its properties, however; MAPP and KMnO4 treated commingled composites showed much better stability towards thermal oxidation brought about by the solar concentrator, compared to untreated sample and neat polypropylene. This increased resistivity of treated composites (especially MAPP and KMnO4) towards thermal oxidation brought about by the solar concentrator is due to the increased interfacial adhesion between the matrix and jute yarn owing to chemical modifications. The significance of effective stress transfer between the PP matrix and reinforcing jute yarns is evident from the increased tear resistance of PP/jute yarn commingled composites with increasing fibre content and also with different chemical treatments.

This project report describes the measurement of Fuel level. Capacitive sensor is used to monitor the fuel in a tank. Capacitive sensor senses the level because of the change in dielectric between the plates of the capacitor. Since it has no moving parts Capacitive level sensors are considered to have minimum maintenance and high accuracy. Capacitive sensors can measure any material whose dielectric constant is known. It measures the level continuously.

Bi-modal porous structured TiO2-ZrO2 composites were developed on glass substrates using dip coating technique. Porosity and reduction in particle agglomeration were achieved through the incorporation of Pluronic F127. Porous nature of the film was studied using field emission scanning electron microscopy (FE-SEM) and structure formation was investigated by high angle annular dark field (HAADF) images. Raman imaging and elemental mapping revealed the presence of Ti, Zr and O elements Photo-induced hydrophilic self-cleaning property (dye degradation) was observed for both double templated and UV irradiated samples. A feasible mechanism has been evolved to explain the retainability of hydrophilic nature of the films.

The thermal and mechanical properties of locally available bio-extracted banana fiber reinforced polypropylene commingled composite systems were studied. An entirely new method was adopted for the extraction of banana fiber, which is through an anaerobic process. The thermal properties of the commingled composite (both treated and untreated) were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed an improved thermal stability for the treated composites. A noticeable increase is observed in the hardness and tensile properties of the treated samples compared to the untreated ones while a decrease is observed for the impact properties of the treated samples. The surface morphology and fiber treatments were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy.

An investigation on Surface Plasmon Resonance (SPR) based fiber optic sensor for mercury detection utilizing copper-silver core shell nanoparticles (Cu@Ag CNPs) was carried out. TEM analysis was used to confirm the formation and morphological characteristics of the CNPs, whereas EDS and AAS analysis were used to validate the successful formation of the core shell nanoparticles. Good selectivity and sensitivity towards mercury were established by means of UV–Vis absorption spectroscopy. SPR based fiber optic mercury sensor was fabricated using Cu@Ag CNPs as the sensing materials and the results clearly prove that the Cu@Ag CNPs can act as suitable candidates for the same.

An innovation will be recognized as successful only if it satisfies all phases of product development; i.e. from the specification to mass production. Therefore, a cost-effective production by keeping the best possible characteristics is vital in any Industry. Large scale production of polymer fibers with ultrafine morphology is such a challenge to the field of nanotechnology. The idea proposed here utilizes the versatile electrospinning technology for the preparation of uniform, beadless and ultraviolet light absorbing polycarbonate (PC) nanofibers. The average diameter limits to 114 nm and that too by using most convenient and comparatively less toxic solvent mixture. This method is simple and so far, it is not reported elsewhere. For THF-DMF system a PC concentration of 17 w/v% and for DCM-DMF system a PC concentration of 15 w/v% was found to be the optimum polymer concentration. The average fiber diameter and bead density were very much influenced by the viscosity, conductivity and concentration of the solution used for electrospinning. The PC fibers (PC concentration of 15 w/v % in DCM-DMF system) with lowest average diameter of 114 nm shows excellent ultraviolet absorption, semicrystalline nature, enhanced glass transition temperature and thermal stability.

Present article scrutinizes the effect of pristine few layers graphene incorporation into NBR matrix via a green approach in terms of mechanical properties and two different fabrication routes viz. latex casting and latex casting followed by dry rubber mixing. Large scale production of pristine few layers graphene was accomplished by means of planetary ball milling and was characterized using X-ray diffraction (XRD), Raman spectroscopy and Transmission electron microscopy (TEM) analysis. The produced graphene and procured MWCNT was then successfully incorporated (separately) into NBR latex. It was found out that at a particular filler loading of 3 phr for latex casting method, 5 phr for dry rubber mixing method and only 0.4 phr for MWCNT based samples the produced nanocomposites demonstrated a significant increment in tensile properties. However, when only the supernatant from the 3 phr graphene dispersion was used, the sample showed an improved increment (363%) in mechanical properties due to the removal of other bulk particles during settling which might otherwise act as stress concentrators inside the composite. The demand for multifunctional elastomers is increasing now a day and hence these findings where pristine graphene has been successfully and uniformly incorporated into NBR matrix (an important synthetic elastomer with huge applications) would be scientifically significant.

Transport properties of thermoplastic composites are an important area of research nowadays. The main limiting factors that control a polymer composite's end user application are (1) diffusion and (2) solvent uptake because both these phenomena cause a change in the mechanical properties of the composites and sometimes even lead to the degradation of the material. A thorough knowledge of the parameters like diffusion, sorption, and permeation coefficients will provide us with an understanding of the solvent uptake in polymers. Liquid transport through thermoplastics is one of the most extensively researched fields in materials science. This chapter gives a brief insight into the liquid transport (both aromatic and aqueous) properties of thermoplastic composites.

The unique physical and optical properties of tellurium-based glasses such as low melting point, low phonon energy, higher linear and nonlinear refractive index, and wide transparency in the visible to IR region make them excellent candidates for telecommunication applications. This chapter reviews trivalent rare-earth (RE3+)-doped tellurium-based glasses developed over a wide range of compositions formed from the viscous melts of more than two glass formers. This chapter includes some important tellurium-based glasses as potential host materials for RE3+ ions having near-infrared (NIR) emissions. The influences of the composition on the spectral as well as laser parameters of certain rare-earth transitions investigated by several researchers are also detailed so as to apply them in a wide variety of practical applications. It also covers some basic theories necessary to explain the spectroscopic features of interest, the required experimental evidences, and the representative data related to the topic from the previous reports. The recent developments in the intensification in NIR luminescence of lanthanide-embedded tellurite-based hosts due to the co-doping of the metal nanoparticles are also addressed.

Polymer composite membrane–based gas separation is still a growing area as efforts for accurate tracing of correlations between thin film composite/membrane structure and its gas transport properties are yet to be complete. This type of gas separation has immense advantages such as low cost, easy handling, light weight, and excellent flexibility. In addition, the greatest advantage of this method is the wide variety of polymers available in the market, which enables the selection of the apt membrane material for separating a particular gas. This field is evolving very rapidly as novel techniques based on mixed matrix composite membranes and other membrane-based hybrid structures are being employed. The key to success is obviously in understanding the relationship between the structure of polymer membrane and the transport through it. This chapter sheds some light on the studies conducted in this regard so far. It also discusses some of the recent findings made in the realm of polymer membrane–based gas transport.

Advancements in water purification techniques are an important area of research nowadays owing to the swiftly growing demand for fresh water. The demand for fresh water is going to grow further in the coming decades, hence the need for cost effective, environmentally friendly techniques for water purification. Current technologies include membrane processes ranging from reverse osmosis, membrane distillation, pervoparation, etc., for drinking water management. The current polymer membranes being used in water purification techniques have several disadvantages related to their mechanical and thermal stability. This article brings together the current applications of carbon-based nanomaterials in water purification techniques owing to their exceptional mechanical, thermal, and antibacterial properties, and high thermal stability.

Ultraviolet (UV)–visible spectroscopy is a promising technique that can be used to characterize nanomaterials with light, which is absorbed and scattered by a sample. The properties of materials change dramatically when their size is reduced to the nanometer range, but the characterization of these nanomaterials is not a simple task. In UV spectroscopy the magnitude, peak wavelength, and spectral bandwidth associated with a nanoparticle are reliant on the particle's size, shape, and material composition. The precise control of nanoparticle size, size distribution, and dispersion at the nanolevel is very important in the specific usage of these materials. The basics of and the important areas related to UV characterization of nanomaterials are discussed in this chapter.

Water pollution is a serious environmental and public concern all over the world. Many toxic metals (e.g., lead and cadmium) even at trace levels are believed to have adverse effects on human health. Thus, it is important to develop efficient technologies for enhanced removal of toxic metal ions from contaminated waters. Various technologies have been developed for the decontamination of water. Nanocellulose has attracted a great deal of interest as a source of nanometer-sized materials because of their biodegradability, easy availability, and the related characteristics, such as a very large surface-to-volume ratio and outstanding mechanical properties. This article assembles the current applications of nanocellulose in the environment, namely as an adsorbent for heavy metals, water purification, antimicrobial and catalytic activities, and a reinforcement for biodegradable materials. Water pollutant remediation by catalytic decomposition of organic pollutants is a growing application of nanocellulose-based nanocomposites.

The viscoelastic properties such as damping behaviour, storage and loss modulus, etc. of polymer composites depend on matrix filler interaction, crystallinity and the extent of crosslinking. It was observed that the storage modulus of the composites increased with the addition of filler due to the enhancement in stiffness of the material. The damping behaviour was found to decrease as a function of filler loading and this was attributed to the restricted movement of the polymer segments. The higher surface area to volume ratio factor of the layered silicate resulted in the better interaction between the polymer matrix and the filler, which resulted in the change in glass transition temperature. The flow properties were studied with special reference to filler loading of different fillers at a specified temperature. It was observed that complex viscosity of filled systems is higher than that of unfilled system. Among the fillers, layered silicate filled systems showed higher viscosity in comparison with calcium phosphate and titanium dioxide fillers.

Commingled biocomposites based on polypropylene/jute yarns were prepared using commingling technique. The thermal and calorimetric behaviour of these commingled composites were studied with respect to fibre content and various chemical treatments. The thermal stability of the composites was found to be in between that of jute fibre and neat polypropylene (PP). Different chemical treatments increased the thermal stability of the composites due to increased interfacial adhesion between the matrix and reinforcement. Jute yarn acts as nucleating agents and favours the process of crystallisation thereby increasing the crystallisation temperature. Chemical treatments further increased the crystallisation temperature as a result of better interfacial adhesion between jute yarn and PP matrix. The close proximity of jute yarns weakens the mechanical bonds between PP molecules resulting in marginal lowering of melting temperatures. Polarized optical microscopic studies revealed the formation of transcrystalline layer around the jute fibre after 6 h.

Polypropylene and jute yarns were used to prepare commingled composites using commingling technique where the natural fibres are subjected to minimal shear forces. The dielectric constant, loss factor and conductivity increased with fibre content where as volume resistivity decreased due to the better net orientational polarisation in jute yarn reinforced polypropylene (PP) commingled composites. However due to a reduction in the hydrophilic nature of jute yarns brought about by chemical treatments the dielectric constants and conductivities of treated composites was less than that of the untreated ones as a result of reduction in orientational polarisation and moisture absorbance. As temperature increased the dielectric constant, loss factor and conductivity first increased up to a particular temperature and then decreased due to a reduction in orientational polarisation brought about by the increased molecular vibrations with increasing temperature. Wet samples showed much higher dielectric constant and conductivity values compared to their dry counterparts.

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