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The natural rubber/graphene quantum dots (GQDs) nanocomposites were prepared and their properties have been studied. Graphene oxide prepared via modified Hummer’s method was the precursor used to synthesis graphene quantum dots. The two-roll mill was used for the compounding of the natural rubber/graphene quantum dot (NR/GQD) nanocomposites. The nanocomposites are characterized using UV–visible Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), X-ray Diffraction Analysis (XRD), Thermogravimetric Analysis (TGA). The mechanical and diffusion properties of the natural rubber/graphene quantum dot (GQDs) nanocomposites were also investigated. The TEM analysis revealed that GQD has tiny spherical shaped morphology with an average size value of 5 nm. The FTIR and XRD studies clearly showed the strong interaction between GQDs and NR and the peak at 8.49 0 in the diffractogram of nanocomposites indicates the uniform distribution of GQDs in matrix of NR. The incorporation of 1phr of GQD shows a 30%, 13% and 23% of enhancement in respective tensile strength, elongation at break and young’s modulus of the NR/GQD nanocomposite compared to that of pure natural rubber. The study found that the incorporation of GQDs into the natural rubber matrix dramatically increased the mechanical and thermal properties of the of NR. The nanocomposite with 1.5 phr of GQD showed higher thermal stability and is ascribed to the uniform dispersion and interaction of GQD in the NR matrix. The GQD will act as a protective barrier and thus it arrests the thermal decomposition by absorbing the heat that liberated in the matrix.

Rheology and Processing of Polymer Nanocomposites examines the current state of the art and new challenges in the characterization of nanofiller/polymer interactions, nanofiller dispersion, distribution, filler-filler interactions and interfaces in polymer nanocomposites.

Wettability, stainability and diffusion properties of polymer (PMMA) based nanocomposites (PMMA/ZnO) have been explored with critical significance to their physicochemical perspectives and clinical implications in the maxillofacial rehabilitation of cancer and trauma patients. Wetting and diffusion of artificial saliva through the neat polymer and nano composites have been investigated in detail. The same protocol was adopted for water diffusion studies at different temperatures. Transportation mechanism and surface wettability and stainability by commonly used beverages like tea, coffee and turmeric on these composites are studied in detail. Inferences are correlated with morphological analysis by Atomic Force Microscopy (AFM) and surface roughness parameters and density measurements. No studies have been reported till date about correlating wetting enhancement to retentive qualities and diffusion resistance to anti-stainability of the prostheses in the biomedical field. Findings of the present study is highly relevant and promising as these membranes/composites offer better retention and adaptability for the prostheses on tissue base which stimulates blood circulation in that region which prevents further bone resorption. Anti-staining potential offer more acceptance and durability for the maxillofacial prostheses especially intra orally. This nano formulation is a highly durable, cost effective esthetic substitute for the conventional polymer PMMA. Graphical abstract

Hybrid fillers are making a remarkable improvement in the properties of polymeric systems. In the present study, the influence of hybrid of multiwalled carbon nanotube (MWCNT) and nanoclay on the mechanical, electrical and transport properties of nitrile rubber (NBR)/natural rubber (NR) blends has been investigated. Attempts were made to prepare NBR/NR/CNT/nanoclay composites on a two-roll mill and to study various mechanical properties such as tensile strength, tear resistance, abrasion loss and compression set percent. Transport, thermal and electrical properties were also investigated. By virtue of the synergism between MWCNT and nanoclay, the composites exhibited enhancement in the mechanical properties by the immobilization of rubber chains via coupling action between the filler surface and the rubber molecules. The fine and uniform dispersion of both CNT and clay in composite samples supported the observation. The hybrid filler system had a great impact on the thermal and electrical properties of the composites. Graphical abstract

In the present study efforts have been made to prepare organoclay nanocomposites of NR/NBR (natural rubber/nitrile rubber) blends using 0-4 wt% cloisite 93A by mixing on a laboratory type two-roll mill as per ASTM procedure. The organoclay-filled NR/NBR blends exhibited high tensile strength due to the formation of inter-phase crosslinks. The modulus values were also found increase in line with tensile strength. The clay platelets could be aligned in the direction of stretching of the rubber sample and the strong interfacial interaction between the NR and the NBR chains and the clay platelets could support local load transfer, resulting in enhanced modulus. The results of Scanning Electron Microscopy (SEM) fractographic analysis were in agreement with the mechanical test results and support the observed changes in the NR/NBR blend properties as the clay content increases. Transmission Electron Microscopy (TEM) images showed intercalated clay layers in both phases of the blend, indicating good compatibilization. Crosslink densities of the vulcanized samples exhibited an increase in the values on the increase in dosage of the nanoclay, supporting the fact that high specific surface area of the layered silicates enhanced reinforcement of the polymer matrix. Graphical abstract ᅟ

Human hair is a protein fiber and its potential is barely explored. In this study, human hair/natural rubber (NR) composite was prepared by two-roll mixing method. The effect of hair loading on the structural, morphological and thermal behaviour of the composite were investigated. Human hair reinforced composite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Thermogravimetric Analysis (TGA) followed by various mechanical characterizations. The mechanical properties showed optimum results for low hair concentrations. After the inclusion of human hair in the rubber matrix, the tensile strength increased by 44%, tear strength by 60%, hardness by 144% and the relative abrasion resistance index by 44%. The thermal stability was also retained after the addition of human hair. The enhancements in mechanical properties were substantiated from SEM and AFM analyses and these were attributed to the proper dispersion of cut human hair in the NR matrix.

Exploiting polymer nanocomposites as dielectric and heat storage devices is an important approach to develop high performance materials. Graphite (GT), thermally reduced graphene oxide (TRG), and hybrid consisting of TRG and ionic liquid (1-Ethyl-2, 3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide) modified carbon nanotubes (IMCNT) were added to natural rubber and membranes were fabricated via melt mixing method. The amount of the GT, TRG, TRG+IMCNT used in this work was in the range of 0.5 to 5 wt%. Mechanical properties of NR nanocomposites revealed that the hybrid (TRG+IMCNT) (5 wt%) system showed high tensile strength, high modulus and low elongation at break as compared to neat NR, NR reinforced with GT (5 wt%) and NR reinforced with TRG (5 wt%) systems owing to the synergistic hybrid effect caused by the network formation of the hybrid fillers inside NR matrix. Dielectric properties of the prepared membranes were studied at 2.5, 10 and 20 GHz in the microwave frequency region using a Split Post Dielectric Resonator (SPDR) based technique. The incorporation of micro and nanofillers in the natural rubber (NR) matrix results in consistent improvement in dielectric constant and lower loss tangent values. In certain cases the samples containing 5 wt% of filler exhibited high loss or conducting behaviour at higher frequencies (10 and 20 GHz). Different techniques had to be employed for measuring the dielectric constant and loss tangent of the prepared membranes where they showed a high loss or conducting behaviour. Moreover, thermal history like glass transition temperature and the change in heat capacity were estimated using Differential Scanning Calorimetry (DSC). In addition, the dispersion of micro and nanofillers inside the NR was estimated using X-ray followed by Transmission Electron Microscopy for the morphology architecture of nanofillers. The morphology of the prepared membranes was correlated with the mechanical, dielectric and thermal properties. The hybrid system (TRG+IMCNT) exhibited high dielectric constant (5.6) and low heat capacity value (0.32 J/g/°C) as compared to GT and TRG systems.

In this report, we demonstrate that both mechanical behaviour and thermal stability of polybutadiene rubber (PBR) nanocomposites could be improved by incorporating exfoliated graphite (EG) using melt mixing method. Incorporation of the filler EG in the polybutadiene (PBD) matrix is confirmed by infrared spectra and X-ray diffraction analysis. The structural characteristics, mechanical properties and thermal properties of these newly modified PBR nanocomposites were systematically analysed and studied. Thermal properties of the nanocomposites were studied using thermogravimetric analysis under nitrogen atmosphere. Thermogravimetric studies showed that PBR8 is having higher thermal stability than that of the PBR gum sample. Mechanical properties like tensile strength, Young’s modulus, tear strength, hardness and compression set of the nanocomposites were studied. Mechanical properties are also high for the modified PBR nanocomposites with maximum filler content. The permeability of organic vapours such as dichloromethane (CH2Cl2), chloroform (CHCl3) and carbon tetrachloride (CCl4) through PBR/EG nanocomposites was also studied. In vapour permeation studies, PBR4 exhibits the least permeability in CH2Cl2, CHCl3 and CCl4 solvents. Polybutadiene rubber–natural graphite (PBR/NG) nanocomposites were also prepared for comparison.