Rabiranjan Murmu

In this study, micrographite (μG)-reinforced polypropylene (PP) composites were fabricated using melt compounding, with μG contents varying from 3 to 15 wt%. The composites were evaluated for mechanical, electrical, and thermal performance, addressing a relatively underexplored area among carbon-based fillers. Tensile testing across elongation speeds (10–50 mm/min) showed up to ~30% strength improvement at 6 wt% μG due to good dispersion and stress transfer, while ≥9 wt% led to agglomeration, reduced ductility, and increased melt resistance. SEM fractography confirmed matrix–filler debonding and brittle behavior at higher loadings, with ductility improving at higher elongation rates. A sharp drop in resistivity near 6 wt% indicated the formation of a conductive network, and thermal conductivity improved by nearly 80%. Taguchi optimization identified 12 wt% μG and 50 mm/min as optimal for tensile strength, with filler content having a stronger influence than testing speed. The novelty of this work lies in its integrated structure–property investigation across a broad μG range, offering a scalable, multifunctional PP composite system suitable for semi-structural, conductive, and thermal management applications.

It is difficult to select low-cost filler materials. Specifically, carbon-based filling materials are a matter of concern, and developing a carbon-filled polymer composite with enhanced properties is necessary. In this study, the authors developed a polymer composite using virgin polypropylene (PP) as a matrix and affordable micrographite (µG) as a filler. The developed composite has many potential applications in the automotive, aerospace, and electronic industries. To prepare the test specimens, the composite was prepared using a twin-screw extruder containing 3, 6, 9, 12, or 15 wt.% µG powder (BET surface area ≈ 29 m²/g; particle size > 50 µm) followed by injection molding. Different mechanical properties like the tensile, flexural, and impact strengths were determined. The prepared composites were further characterized by means of XRD, TGA, DSC, FTIR, DMA, FESEM, and PLM tests. The results were analyzed and compared with those for PP. Improved tensile (up to ≈ 34 MPa) and flexural (up to ≈ 40 MPa) strength was observed with an increase in the µG content. However, the impact strength continuously decreased (maximum ≈ 32 J/m for PP) with fractures. These findings underscore that graphite plays a significant role in controlling the deformation behavior and ultimate strength of composites. An XRD analysis revealed that adding graphite restructured the crystalline arrangement of PP and altered the composite’s crystallographic properties. Nonetheless, no induction effect (β-phase formation) was observed. A moderate enhancement in the thermal stability was observed owing to a small increase in the melt (T_m), onset (T_onset), and residual (T_R) temperatures. A microstructural analysis showed that the micrographite powder strongly prevented spherulite growth and modified the graphite powder’s rate of dispersion and agglomeration in a polymer matrix. The results show that graphite could be a viable low-cost alternative carbon-based filler material in polypropylene matrices.

Journal of Polymer Materials An International Journal is published quarterly (4/year), which covers the important fundamentals of Polymer Science and Technology. Prints Publications

The authors developed a nanocomposite using polypropylene (PP) and graphene nanoplatelets (GNPs) with a melt mixing method. Virgin PP was filled with three sets of GNPs with a fixed thickness (15 nm) and surface area (50–80 m²/g). The selected H-type GNPs had three different sizes of 5, 15 and 25 µm. The nanocomposites were made by loading GNPs at 1, 2 and 3 wt.%. Mechanical analysis was carried out by performing tensile, flexural and impact strength tests. The crystalline, micro-structural, thermal and dynamic mechanical properties were assessed through XRD, FESEM, PLM, DSC, TGA and DMA tests. It was observed that all three types of GNPs boosted the mechanical strength of the polymer composite. Increasing the nanofiller size decreased the tensile strength and the tensile modulus, increased the flexural strength and flexural modulus, and increased the impact strength. Maximum tensile strength (≈41.18 MPa) resulted for the composite consisting 3 wt.% H5, whereas maximum flexural (≈50.931 MPa) and impact (≈42.88 J/m) strengths were observed for nanocomposite holding 3 wt.% H25. Graphene induced the PP’s crystalline phases and structure. An improvement in thermal stability was seen based on the results of onset degradation (T_D) and melting (T_m) temperatures. Graphene increased the crystallization (T_c) temperatures, and acted like a nucleating agent. The experimental analysis indicated that the lateral size of graphene plays an important role for the nanocomposite’s homogeneity. It was noted that the small-sized GNPs improved dispersion and decreased agglomeration. Thus overall, small-sized GNPs are preferable, and increasing the lateral size hardly establishes feasible characteristics in the nanocomposite.

A novel cost effective Chitosan-PVA-Red Mud (RM) hybrid membranes are developed and their morphological and physiochemical properties are studied. The addition of RM enhanced IEC and bound water content in a composite membranes. The hydroxyl groups are consumed due to the interaction with silica oxides and depleted the crystalline phase of the composites. The tensile strength and modulus of the composite membranes were reduced. The addition of RM improves the thermal stability of the composite membrane and shifts the degradation process to a higher temperature. The RM nanoparticles depleted the hooping sites for methanol transport in the composite membrane and the permeability value reported in the modified membrane was one order lower than the Nafion (N117) membrane. The proton conductivity of the composite membranes are obtained by fitting the EIS data in an equivalent circuit model. The composite membrane provides higher proton conductivity at reduced relative humidity conditions and the proton transport was governed by Grotthus mechanism. The modified membrane provides the maximum power density of 44mW/cm² at a current density of 140mA/cm². The durability test was conducted at a current density of 0.15 Acm² and 70°C for 144h to evaluate fuel cell performance and voltage decay. The durability study confirms that the modified membrane provides higher cell stability with marginal drop in cell voltage (1.76%). The reduction of methanol cross-over and the enhancement of membrane selectivity increases power density of the direct methanol fuel cell.

We used a new strategy to develop a hybrid membrane by impregnating hygroscopic zirconia and ionic liquid in the chitosan-PVA blend. The effects of ionic liquids on the water uptake, IEC, phase transition behavior, methanol permeability, and proton conductivity of the hybrid membrane were studied. The ionic liquids have a synergetic effect on the chain flexibility and tensile strength of the thin film. The developed hybrid membrane has the lowest methanol permeability of 0.94 × 10⁻⁷ cm²s⁻¹. The polarization curve obtained for a fuel cell operating at 70°C and 2 M methanol feed provides the maximum power density of 97 mWcm⁻². Graphical Abstract

Graphene has accomplished huge notoriety and interest from the universe of science considering its exceptional mechanical physical and thermal properties. Graphene is an allotrope of carbon having one atom thick size and planar sheets thickly stuffed in a lattice structure resembling a honeycomb structure. Numerous methods to prepare graphene have been created throughout a limited span of time. Due to its fascinating properties, it has found some extensive applications to a wide variety of fields. So, we believe there is a necessity to produce a document of the outstanding methods and some of the novel applications of graphene. This article centres around the strategies to orchestrate graphene and its applications in an attempt to sum up the advancements that has taken place in the research of graphene.

The composition of nickel-based metal matrix NiCrBSi was varied with 5%, 10% and 15% of Al₂O₃ particles to obtain high wear resistant coatings by means of a high-velocity oxy fuel (HVOF) thermal spraying process. The coating was characterized by optical microscope, scanning electron microscope (SEM) and X-ray diffractometer (XRD). The physical properties of coatings such as porosity, thickness, surface roughness, surface hardness, fracture toughness, bond strength and density were measured and compared. The experimental design of Taguchi L27 orthogonal array was employed to study and compare the effect of parameters such as impingement angle, impact velocity and alumina per cent in the coating on erosion. The coating containing 15 wt.% of Al₂O₃ and erodent speed of 33 m/s striking at inclination angle of 30° proved to be the best arrangement in preventing volume loss to a minimum of 0.00015 cc due to low-impact energy, high bond strength and high surface hardness. Analysis of variance (ANOVA) supported the assertion that the impact angle (A) of erodent and composition (C) were the factors contributing most to the volumetric loss as indicated by their combined effect A × C leading to the highest combined factor of 7.34. The scanning electron microscopy (SEM) images of the eroded coatings reveal that the mechanisms of erosion were the fracturing of splats, development of craters, micro cutting and ploughing action.