Effect of lignocellulosic corn stalk on mechanical, physical, and thermal properties of injection moulded low density polyethylene composites: An approach towards a circular economy.

Escalating concern over global warming, which is mostly associated with deforestation, has led to the development of new classes of materials that can replace wood and better utilise natural resources. Presently, waste is a significant factor in recycling. In this regard, one of the leading contributors to waste is agricultural waste, which includes dried branches, leaves of trees, plants, and other organic materials. In the current study, waste from corn agriculture was utilised as a potential reinforcement for the fabrication of corn stalk-low density polyethylene (CS-LDPE) composites via an injection moulding technique at 170 °C. The different parameters were assessed to develop composites using CS, including physico-chemical, macromolecular, mineralogical, elemental, and morphological analysis. The amount of corn stalk (CS) was varied from 10 to 50 wt% with respect to the polymer. The mechanical, physical and thermal performance of the composites was examined. The density and water absorption of the composites were found to remain within the ranges of 1.00-1.11 g/cm3 and 0.22-1.01 %, respectively, whereas these parameters increased as the proportion of CS increased. The thermal conductivity decreases with the addition of CS from 0.36964 ± 0.020 to 0.22388 ± 0.002 W/mK. It was observed that adding CS to the composites increased their tensile and flexural properties, but decreased their impact strength. The maximum flexural strength of 14.40 ± 1.558 MPa, flexural modulus of 752.53 ± 180.409 MPa, tensile strength of 10.49 ± 0.946 MPa and tensile modulus of 539.79 ± 91.044 MPa were observed with a 50 % CS content. The results suggest that these materials have considerable potential to serve as a cost-effective substitute for the conventional lignocellulosic fillers in the manufacturing of wood-plastic composites.

Extremely Reduced Dielectric Constant and Band Gap Enhancement in Few-Layered Tungsten Disulfide Nanosheets.

Highly crystalline few-layered tungsten disulfide (WS2) nanosheets were synthesized via a cost-effective, low-temperature hydrothermal route. X-ray diffraction and HR-TEM analysis confirmed the formation of hexagonal nanosheets with thickness of ∼6-8 nm. Raman analysis and AFM results confirmed the few-layered 2H phase of WS2 nanosheets. The UV-vis study shows absorption peaks at 219 and 271 nm with large band gap value of ∼3.12 eV for WS2 nanosheets. Surprisingly, WS2 nanosheets show a dielectric constant of approximately ε' ≈ 5245, whereas bulk WS2 material exhibits a dielectric constant of 7482373. An almost 1426-fold decrease in the value of dielectric constant for the WS2 nanosheet is observed. Such an extreme reduction in dielectric constant and observance of large band gap in WS2 nanosheet were observed for the first time. The present study reveals the excellent and unusual optical and dielectric properties for their potential application in optoelectronic, dielectric, solar, phosphor, and various nanoelectronic devices.

Transforming Marble Waste into High-Performance, Water-Resistant, and Thermally Insulative Hybrid Polymer Composites for Environmental Sustainability.

Marble waste is generated by marble processing units in large quantities and dumped onto open land areas. This creates environmental problems by contaminating soil, water, and air with adverse health effects on all the living organisms. In this work, we report on understanding the use of calcium-rich marble waste particulates (MPs) as economic reinforcement in recyclable polypropylene (PP) to prepare sustainable composites via the injection molding method. The process was optimized to make lightweight and high-strength thermally insulated sustainable composites. Physicochemical, mineralogical, and microscopic characterization of the processed marble waste particulates were carried out in detail. Composite samples were subsequently prepared via the injection molding technique with different filler concentrations (0%, 20%, 40%, 60%, and 80%) on weight fraction at temperatures of 160, 180, and 200 °C. Detailed analysis of the mechanical and thermal properties of the fabricated composites was carried out. The composites showed a density varying from 0.96 to 1.27 g/cm3, while the water absorption capacity was very low at 0.006%-0.034%. Marble waste particulates were found to considerably increase the tensile, as well as flexural, strength of the sustainable composites, which varied from 22.06 to 30.65 MPa and 43.27 to 58.11MPa, respectively, for the molding temperature of 160 °C. The impact strength of the sustainable composites was found to surge with the increment in filler concentration, and the maximum impact strength was recorded as 1.66 kJ/m2with 20% particulates reinforcement at a molding temperature of 200 °C. The thermal conductivity of the particulates-reinforced sustainable composites was as low as 0.23 Wm-1K-1 at a 200 °C molding temperature with 20% and 40% filler concentrations, and the maximum thermal conductivity was 0.48 Wm-1K-1 at a 160 °C molding temperature with 80% filler concentration. Our findings have shown a technically feasible option for manufacturing a lightweight composite with better mechanical and thermal properties using marble waste particulates as a potential civil infrastructural material.

Jarosite characteristics and its utilisation potentials.

During metallic zinc extraction from zinc sulphide or sulphide ore, huge quantity of jarosite is being released universally as solid residues. The jarosite mainly contains iron, sulphur, zinc, calcium, lead, cadmium and aluminium. Jarosite released from such industrial process is complex and its quality and quantity make the task more complex for safe disposal. Apart from water contamination, jarosite already accumulated and its increasing annual production is a major source of pollution for surrounding environment including soil, vegetation and aquatic life and hence its disposal leads to major concern because of the stringent environmental protection regulations. An attempt was made to evaluate the characteristics of Indian jarosite with an objectives to understand its potentials for recycling and utilising as raw materials for developing value added products. Sand and Coal Combustion Residues (CCRs) was used as an admixture to attain good workability and detoxify the toxic substance in the jarosite. Result revealed that jarosite is silty clay loam in texture having 63.48% silt sized and 32.35% clay sized particles. The particle size of jarosite (D90=16.21+/-0.20 microm) is finer than the CCRs (D90=19.72+/-0.18 microm). The jarosite is nonuniform in structure and shape as compared to the CCRs having spherical, hollow shaped and some of them are cenosphere in nature. The major mineral phase of jarosite is Potassium Iron Sulphate Hydroxide {KFe3(SO4)2(OH)6}and Iron Sulphate Hydrate {2 Fe2O3SO3 x 5 H2O}. In CCRs the dominant phases are quartz {SiO2}, mullite {3 Al2O3 x 2 SiO2} and hematite {Fe2O3}. The high electrical conductivity of jarosite (13.26+/-0.437 dS/m) indicates that the presence of cations and anions are predominant over CCRs (0.498+/-0.007 dS/m). The major portion of jarosite consists of iron (23.66+/-0.18%), sulphur (12.23+/-0.2%) and zinc (8.243+/-0.075%). But CCRs main constituents are silicon (27.41+/-0.74%), aluminium (15.167+/-0.376%) and iron (4.447+/-0.69%). The other constituents such as calcium, aluminium, silicon, lead, and manganese are also present in the range of 0.5 to 5%. Heavy metals such as copper, chromium, and cadmium are found higher in jarosite as compared to the CCRs. The statistically designed experimental trials revealed that the density, water absorption capacity and compressive strength of fired jarosite bricks are 1.51 gm/cm3, 17.46% and 43.4 kg/cm2 respectively with jarosite sand mixture in the ratio of 3:1 indicating the potentials in developing building materials.

Advances in industrial prospective of cellulosic macromolecules enriched banana biofibre resources: A review.

Biological macromolecules enriched resources are rapidly emerging as sustainable, cost effective and environmental friendly materials for several industrial applications. Among different biological macromolecules enriched resources, banana fibres are one of the unexplored high potential bio-resources. Compared to various natural fibres such as jute, coir, palm etc., the banana fibres exhibits a better tensile strength i.e. 458 MPa with 17.14 GPa tensile modulus. Traditionally used petroleum based synthetic fibres have been proven to be toxic, non-biodegradable and energy intensive for manufacturing. Cellulosic banana fibres are potential engineering materials having considerable scope to be used as an environmental friendly reinforcing element for manufacturing of polymer based green materials. This paper summarizes the world scenario of current production of biological macromolecules rich banana residues and fibres; major user's of banana fibres. The quality and quantity of biological macromolecules especially the cellulose, hemicellulose, lignin, wax, engineering and mechanical properties of banana biofibre resources are reported and discussed. Subsequently, the findings of the recent research on bio resource composites, materials performance and opportunities have been discussed which would be a real challenge for the tomorrow world to enhance the livelihood environmental friendly advancement.