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Abstract: Graphitic carbon nitride (g-C3N4) is an extraordinary semiconductor photocatalyst (PC), which transforms solar energy into chemical energy for the photodisintegration of several noxious organic contaminants into non-toxic derivatives. Polymeric g-C3N4 is a metal-free PC with high chemical stability, eco-friendly composition, and suitable energy band potential that absorb a significant portion of the solar spectrum. Despite its outstanding characteristics, g-C3N4 has some limitations, including low visible light absorption, low surface area, and rapid recoupling of charge carriers. These limitations over-shaded its proficient efficiency as a PC. The current g-C3N4 related research focuses on developing g-C3N4 nanocomposites (NCs) with high-surface-area, broad lightabsorbing, and reduced recombination via physicochemical modifications. This review highlights the latest developments in the synthesis and application of pristine g-C3N4 and its NCs with inorganic constituent and nanomaterials. A critical analysis of the strategies to enhance g-C3N4’s photocatalytic efficiency via excited charge separation and visible light absorption is also presented. Furthermore, the photocatalytic degradation of organic pollutants (OPs), including dyes, phenol, antibiotics, and pharmaceutical drugs, is summarized herewith.

Superior reinforcement effect along with other useful composite properties are offered by uniformly dispersed in situ incorporated zirconia in chloroprene rubber matrix.

Itaconic acid has been employed as a special facilitator to construct divalent metal ion based ionic crosslinking framework in the acrylonitrile butadiene rubber matrix. Readily accessible double bonds in itaconic acid could directly react with the elastomer to form effective covalent bonds. On the other hand, presence of easily dissociable protons in itaconic acid enables them to form ionic bonds that leads to an increase in crosslinking density of the vulcanizates. The synergistic effect of covalent crosslinking induced by peroxide and ionic crosslinking induced by metal carboxylate could effectively enhance the overall mechanical and dynamic mechanical properties of the rubber composites. In this study, three metal oxides, that is, zinc oxide, magnesium oxide, and calcium oxide, have been selected for this purpose. Tensile strength of nitrile rubber composites depends on the strength of ionic crosslinks, which in turn is influenced by the size of the alkaline earth metals, such as Mg, Ca, etc., and stoichiometric quantity of itaconic acid, which is at par in the formulation of this study. The novelty of this study is that the introduction of a dicarboxylic acid in combination with metal oxides enhances the crosslink density and tensile strength of nitrile rubber composites which could result from the metal organic framework.

The administration of worn tires might be a worry in industrialized nations. The apparatus of morsel elastic as light-weight mix in bond principally based materials might be an unpracticed different for reusing this material. High substitutions of normal sand by morsel elastic were concentrated partner degreed an air-entraining specialist was used to affirm a cell structure inside the cement based composite. The acquired outcomes from tests in contemporary state uncover partner degree improvement in functionality. The tests led on solidified composite show guarantee for productive applications any place warm and acoustic properties region unit required. The aim of the study as sand replacement of rubber powder 0% to 10% in with mix of 1:3 ratios of cement mortar cubes. To the base requirement of mechanical strength for fine aggregate work was accomplished, since compressive strength differed somewhere in the range of one and ten percentage. At long last, potential applications as a development material are featured. The study reveals that optimum replacement of rubber powder in cement mortar cubes as 3% of up to 15%without treatment of chemical compounds and with treatment of chemical compound of Potassium hydroxide in Air Entrained Rubber (AER).

Zirconia particles are generated into a nitrile rubber (NBR) matrix via a solution sol–gel method in a controlled manner. Formation of zirconia particles from their precursor (zirconium(IV) propoxide) occurs under optimized reaction conditions. As a result, the nanoparticles are embedded and well dispersed in the NBR matrix that results in a remarkable improvement in mechanical and thermal properties of the composite. Such reinforcement is not realized when the composites are prepared following the conventional technique of filler loading by physical mixing, although the filler content remains the same. Use of a surface active coupling agent TESPT (bis-(3-triethoxysilylpropyl) tetrasulfide) in the reactive sol–gel system is found to further boost the mechanical performance of the composites. In order to ensure the practical application of the developed composites, a series of studies have been performed that consist of dynamic performance, swelling, thermal degradation, and resistance to oil, ozone, and abrasion. Analysis of the results reveals that in situ zirconia could be an excellent filler for the NBR composites to withstand in a harsh and adverse environment.

Concrete is considered the most commonly used building material. The significant exploitation of crumb rubber waste in concrete. Reductions in strength comparatively high unevenness in durability performance are major factors preventing in concrete. This research focused on using crumb tire rubber as partial replacement of fine aggregate mixed with concrete. This Study reveals that the study of rubberized concrete with replaced control concrete. Ravage tire rubber in the form of scrap rubber was replaced for sand as fine aggregates from 0% to 15% in multiples of 3%. Investigative studies were performed with and without KOH treatment solution and the results were compared with Compressive strength, split tensile strength and flexural strength obtained in the laboratory. The test results showed that even though the compressive strength is condensed when using the crumb tires, it can meet the strength requirements partial replacement of rubber. It was observed that 6% replaced non treated and 9% of treated crumb rubber for compressive strength. For a split tensile strength optimum replace of crumb rubber as 9% for non-treated rubber and 12% for treated crumb rubber. In the flexural strength of specimens, steady raises were observed as the percentage of crumb rubber was increased. However treated and non-treated crumb rubber replacement of fine aggregate flexural strength good for up to replacement of 15% both. In these study tire crumb rubber as promising materials used in concrete to save natural mineral resources in some extent.

Concrete is globally recognized for its long term service period in the application of concrete. In the region of five billion tons of concrete are utilized more or less in the planet and increasing every year. In view of the environmental problems faced today considering the fast reduction of natural resources like sand and aggregate. Owing to the growth of Science and Technology in recent decades, there is a modification in the practice of concrete along with some additives as the complement for strength and workability.Basalt Fiber is categorized under the Mineral additive and brought into usage in early 1920’s in the period of World war for Military purposes. Silica fume is hugely known for its durability and it increases the density of concrete. On Another hand, the building are often subjected to risk of corrosion and Sustainability, the application of any element in the proportions of concrete will possess the property of Resisting and rejuvenating the nature of Concrete.

The interaction between tire rubber and pavement surface depends upon their surface characteristics and physical properties. Presence of water on the pavement surface aggravates the interaction and decreases the skid resistance drastically. Due to the interfacial water, the real contact area between pavement and tire decreases, which leads to decreased Coefficient of Friction (CoF). It is reported that CoF in this triphasic system (tire- water – pavement) can be derived from three components: hysterical, dry adhesion (tire-pavement) and wet adhesion (tire- water – pavement). The present study analyses a mechanistic-empirical model to evaluate the CoF between pavement and tire in wet conditions considering Surface Free Energy (SFE) characteristics of materials. The present study was conducted on five distinct types of rubber samples prevalent in Indian condition with basalt rock chosen as the surface mimicking pavement. Physical properties of the rubber samples (Hardness, material yield strength and tan delta values) were determined according to the ASTM standards. SFE parameters were calculated by measuring the contact angles using Sessile drop method. Surface roughness of basalt aggregate was measured using a Zeta Profilometer. Actual friction coefficient was measured using British pendulum (BP) tester under wet conditions. Further, theoretical CoF was calculated by inputting the experimental material properties into mathematical model. The results showed that the wet adhesive friction was the main contributor to the theoretical CoF, whereas dry adhesive friction was the least. Also, the correlation between actual CoF and the material properties was tried. The actual CoF showed fairly good correlation with the hardness of the rubber samples (R2 = 0.95). The study concludes that the SFE based model to determine friction coefficient between wet pavement and road shows potential to ascertain the frictional interactions taking place between the two surfaces.

Ultra-thin graphene has been receiving significance in the diverse sections of material science, owing to its exceptional physicochemical and thermo-mechanical characteristics. Currently, the fabrication of high-grade graphene in an economical target and green procedures area is a massive concern. Among the diverse techniques, chemical-mediated fabrication is believed to be the finest process since it is simple, scalable, and of low-cost; however, it involves noxious or hazardous chemical reducers for producing functional graphene-based Nanocomposites (NCs). Therefore, around the globe, scientists are endeavoring to adopt the bioinspired techniques to manufacture the functional reduced Graphene Oxide (rGO) and reduced Graphene Oxide-Metal/Metal Oxide (rGO-M/MO) NCs. Hence, keeping this issue in mind, the present review article summarize and integrates the current state of knowledge about the diverse bioinspired strategies developed to obtain rGO and rGO-M/MO NCs and their photocatalytic, antibacterial, and cytotoxic assessments.

Titania nanoparticles are introduced in situ into SSBR matrix (solution of styrene butadiene rubber) by solution sol-gel method under controlled reaction condition that shows outstanding reinforcing efficiency because of its favourable morphological features and enhanced polymer-filler interaction. Surface treatment of titania particles in reactive sol-gel system using an organosilane, TESPT (bis-(3-triethoxysilylpropyl)-tetrasulfide) further strengthens the reinforcement effect. Notably, more than 85% conversion of titania from it's precursor (titanium n-butoxide, TNB) is achieved within 1 h reaction time without employing any catalyst. Additionally, controlled growth of titania particles inside rubber matrix imparts particular characteristics of the titania particles that enables them to deliver rich dielectric and antifungal properties to the composites. In-depth investigation of the composites including rheological, thermal, morphological, mechanical, dynamic mechanical, dielectric and antifungal studies have been carried out and structure-property relationship is established in respect to SSBR gum and externally titania filled composites prepared at similar condition.

Functionalization of non-polar ethylene propylene diene monomer (EPDM) rubber by melt grafting of maleic anhydride (MA) and in situ incorporation of sol–gel derived silica in the MA grafted EPDM has been done to prepare EPDM/silica composites to use dual benefits of both the approaches, which results in adequate rubber–filler compatibility, good filler dispersion, and enhanced composite properties. Controlled growth of silica up to 25 parts per hundred rubber (phr) is carried out with the solution sol–gel process using tetraethoxysilane (TEOS) as a silica precursor. Mechanical and dynamical properties of the composites are found to improve consistently as silica content increases. Furthermore, treatment of maleic anhydride grafted EPDM by γ-aminopropyltrimethoxysilane (γ-APS) results in remarkable improvement in composite properties even at the same silica content. This is attributed to the generation of uniformly dispersed spherically shaped nanosilica throughout the rubber matrix as observed in a transmission electron microscopic (TEM) study. This contributes to enhanced crosslinking density and improved rubber–filler interaction. In fact, the reinforcement effect brought by in situ silica relative to unmodified in situ silica/EPDM composites is found to be much higher than that reported in recent work on EPDM/in situ silica composites even with higher silica loading. The mechanical, rheological, and dynamic mechanical behaviors of all the composites are evaluated and compared in detail.

Remarkable improvement in mechanical properties of acrylonitrile butadiene rubber (NBR) composites is achieved by incorporating nano-titania that is synthesised in solution of the raw rubber using titanium n -butoxide (TNB) as the titania precursor. This is achieved by designed and controlled incorporation of titania that resulted in very good dispersion of titania of nanometric dimension in rubber matrix and enhanced rubber-filler interaction. This sol-gel transformation is carried out under optimised reaction condition. Surface modification of titania by a silane coupling agent (bis-(3-triethoxysilylpropyl)-tetrasulfide, TESPT) causes further improvement in filler dispersion and composite properties when added in the reactive sol-gel system during in situ titania generation rather than it's external addition in the titania filled NBR during mixing and compounding. Thorough characterisation of the composites are done that encompasses a wide range of studies on thermal, morphological, mechanical, dielectric, dynamic mechanical, rheological and antifungal properties. The results are analysed on a comparative basis to investigate the effect of in situ incorporation and in situ surface modification of titania on the composite properties.

Controlled growth of in situ silica, into natural rubber (NR)/nitrile rubber (NBR) blend (40/60 composition by weight) following solution sol–gel method, results in a coherent blend morphology with enhanced composite properties. Similar composites, i.e., in situ silica-filled NR/NBR blend (40/60 by weight), showed better mechanical properties than any other composition that were prepared by soaking sol–gel method in earlier study. However, silica content in the rubber blend was limited to 20 phr (parts per hundred parts of rubber) and could not be increased under experimental condition following soaking sol–gel method. In the present work, silica content is increased (up to 30 phr) beyond that limit for the same blend composition. Accordingly, mechanical properties of the NR/NBR composites are improved. Use of a silane coupling agent, viz., bis-(3-triethoxysilylpropyl)-tetra sulfide, in the reactive sol–gel system during in situ silica generation brings in remarkable effect in silica distribution, rubber–filler interaction and mechanical properties of the composites. TEM micrographs of the selected composites reveal that silica is mostly grown at the interfacial region, when silane is used in particular. This results in further enhancement in mechanical properties and compatibility of the blend at the same silica content as evident from stress–strain and dynamic mechanical analysis studies. The reinforcement of effect in situ silica is assessed by Guth–Gold equation and modified form of Guth equation (with shape factor f = 2.53). The results are supported by the detailed studies on rheological, morphological, mechanical and viscoelastic properties of the composites.

Silica is grown in situ into a natural rubber (NR)/chloroprene rubber (CR) blend (at 40/60 ratio), by a solution sol–gel method, where the silica content in rubber blend is increased in a controlled manner exceeding the limit found for the same blend ratio in the soaking sol–gel method. Reaction conditions have been optimized to get adequate conversion of tetraethoxysilane (TEOS, a silica precursor) to silica. Rheological, thermal, mechanical and viscoelastic properties of all the composites are compared with those of the unfilled rubber blend at similar conditions. Thermal and mechanical properties of the composites are found to improve consistently as silica content in the composite increases owing to increased rubber–filler interaction as revealed in dynamical mechanical analysis (DMA). Further improvement in the properties is observed for a particular composite where a silane coupling agent ((γ-aminopropyl)trimethoxysilane, γ-APS) is used in the reactive sol–gel system during in situ generation of silica. This is attributed to the uniform distribution of silica in the rubber matrix and strong rubber–filler interaction, caused by bifunctionality of silane, as revealed by morphology and DMA studies respectively. The reinforcement effect of silica is evaluated by comparing the experimental results with theoretical values obtained from the Guth–Gold model and the modified Guth model. The present study supplements the in situ silica generation in NR/CR blend of 40/60 ratio, following the solution sol–gel method, to the earlier study involving the soaking sol–gel method where the maximum reinforcement was found for this composition.

The effects of surface modification on the filler–filler and rubber–filler interactions in silica-filled nitrile rubber composites have been studied. Nitrile rubber composites are prepared with untreated stöber silica, organosilane-treated stöber silica and externally added precipitated silica along with organosilane. Morphological studies show better filler dispersion in composites containing silane-treated Stöber silica–filled composites. The studies of the mechanical properties and dynamic mechanical analysis reveal the strong filler–filler interaction (silica agglomerates) in untreated Stöber silica–filled and externally added precipitated silica-filled composites. On the other hand, better rubber–filler interaction is observed for composite filled with Stöber silica treated with bifunctional organosilane.

Nano silica is grown, in situ, in natural rubber (NR)/chloroprene rubber (CR) blends, by the soaking sol–gel method. Much better silica dispersion in the rubber blends is achieved following this technique in comparison to the rubber blends with externally filled silica at the same filler loading and same blend composition. This leads to a significant improvement in modulus, tensile strength and dynamic mechanical properties of all the in situ silica filled composites relative to externally filled composites. Additionally, analysis of glass transition temperature (Tg) values reveals that compatibility of NR and CR in the blend is enhanced when silica is incorporated in situ which in turn contributes to improving the physical properties of the composites. This enhancement in the compatibility of rubber blends is attributed to the preferential accumulation of in situ silica at the interphase of the two constituent rubbers. The best mechanical properties are shown by the in situ filled composite with NR/CR at a 40/60 blend ratio. This result is in agreement with the rheological properties, thermal properties and viscoelastic behaviors of this particular composite. The ultimate properties of the composites are found to be governed by the blend composition, blend compatibility and state of filler dispersion, in addition to the filler content.

Role of silane-treated stöber silica as reinforcing filler for nitrile rubber (NBR) has been studied. Stöber silica is synthesized by sol–gel method, and the surface of silica is modified with the treatment of silane-coupling agent viz. γ-mercaptopropyltrimethoxysilane (γ-MPS) in varying proportions. Average particle size of stöber silica of spherical shape in the range of 200 to 400 nm is evident from scanning electron microscopy (SEM). Surface modification of silica particle with silane-coupling agents decreases surface energy and reduces agglomeration of silica particles in rubber matrix. Stress–strain study and dynamic mechanical analysis of silica-filled composites are compared with the unfilled ones. Analysis of cross-linking density, mechanical properties, and storage moduli indicates a strong rubber–filler interaction in the silane-treated, silica-filled NBR composites. Silane treatment is found to be effective in uniform dispersion of silica in rubber matrix and in improving the mechanical properties of rubber composite. Different functionalities of organosilane at its both end improve the compatibility of silica with rubber matrix and offer better rubber–filler interaction.

Nano silica is generated in situ inside the uncrosslinked chloroprene rubber (CR) by the sol-gel reaction of tetraethoxysilane (TEOS). This results in appreciable improvement in mechanical properties of the CR composites at relatively low filler content. Furthermore, exploitation of reactive organosilanes, γ-aminopropyltrimethoxysilane (γ-APS) in particular, in the silica synthesis process facilitates growing of spherical silica particles with a size distribution in the range of 20-50 nm. The silica particles are found to be uniformly dispersed and they do not suffer from filler-filler interaction. Additionally, it is observed that the silica particles are coated by silane and rubber chains together which are popularly known as bound rubber. The existence of the bound rubber on silica surface has been supported by the detailed investigations with transmission electron microscopy (TEM), energy filtered transmission electron microscopy (EFTEM) and energy dispersive X-ray spectroscopy (EDAX). The interaction between rubber and silica, via bi-functionality of the γ-APS, has been explored by detailed FTIR studies. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43717.

Silica particles were generated and grown in situ by sol–gel method into rubber blends comprised of natural rubber (NR) and acrylonitrile butadiene rubber (NBR) at various blend ratios. Silica formed into rubber matrix was amorphous in nature. Amount of in situ silica increased with increase in natural rubber proportion in the blends during the sol–gel process. Morphology studies showed that the generated in situ silica were nanoparticles of different shapes and sizes mostly grown into the NR phase of the blends. In situ silica filled NR/NBR blend composites showed improvement in the mechanical and dynamic mechanical behaviors in comparison to those of the unfilled and externally filled NR/NBR blend composites. For the NR/NBR blend at 40/60 composition, in particular, the improvement was appreciable where size and dispersion of the silica particles into the rubber matrix were found to be more uniform. Dynamic mechanical analysis revealed a strong rubber–in situ silica interaction as indicated by a positive shift of the glass transition temperature of both the rubber phases in the blends.

This chapter is intended to give an overview of electrical conductivity and dielectric properties of chloroprene rubber (CR) composites with reference to their application in the field of electronics. Influence of different types of filler on the dielectric properties of the CR composites, in a wide frequency range and varying temperature condition, is thoroughly discussed. Type, concentration, and state of dispersion of fillers as well as the polar nature of CR are noticed to play a significant role in governing the electrical conductivity of CR composites. Electrical conductivity studies of carbon black (CB) and carbon fiber-based CR composites are discussed in terms of filler concentration, filler dispersion, and processing techniques. The role of ionic liquid-modified multi-walled carbon nanotube (MWCNT) in improving the electrical conductivity of CR composites is emphatically reviewed. The effects of different types of aging on the electrical properties of CR composites are also focused in this chapter. The CR composites discussed herewith could potentially be used in the field of electromagnetic interference (EMI) shielding, microwave absorbance, and conductive adhesive.

Nitrile rubber/silica composites are prepared by a sol–gel process using tetraethoxysilane as precursor in the presence of γ-mercaptopropyltrimethoxysilane as a silane coupling agent. Here, we follow a novel processing route where the silica particles are generated inside the rubber matrix before compounding with vulcanizing ingredients. The effect of in situ generated silanized silica on the properties of the rubber composite has been evaluated by studying curing characteristics, morphology, mechanical and dynamic mechanical properties. Enhanced rubber–filler interaction of these composites is revealed from stress–strain studies and dynamic mechanical analysis. Excessive use of silane shows an adverse effect on mechanical properties of the composites. Due to finer dispersed state of the in situ silica and enhanced rubber–filler interaction, the mechanical properties and thermal stability of the composites are improved compared to corresponding ex situ processed composite. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40054.