Exploration on Mechanical Behaviours of Hyacinth Fibre Particles Reinforced Polymer Matrix-Based Hybrid Composites for Electronic Applications

Biocomposites with polylactic acid (PLA), nanosilica parts, and water hyacinth fibres have been developed in this experimental study. By changing the weight percentage of nanosilica particulate matter (0, 2, 4, 6, and 8 percent) with PLA and water hyacinth fibres, five composite mates were produced through a double screw extruder and compression moulding machine. According to the ASTM standards, the process to machine, the composite specimens have been adopted from the water jet machining process. The tensile, compression, flexural, impact, hardness, and water absorption tests were performed on the composite specimens to assess various mechanical properties and absorbance behaviour. The test findings reveal the significant improvement in the tensile and flexural properties of the composites. Composites contain 6 percent of the fine nanosilica particles by weight. Concerning adding the growing weight percentage (4 percent) of nanosilica particles to the composites, the water absorption properties of the composites have significantly improved. The tensile strength of 6% nanosilica mixed specimens showed the highest tensile stress rate as 36.93 MPa; the value was nearly 3.5% higher than the 4% nanosilica mixed composite specimens.

Surface Chemistry of Nanohybrids with Fumed Silica Functionalized by Polydimethylsiloxane/Dimethyl Carbonate Studied Using 1H, 13C, and 29Si Solid-State NMR Spectroscopy

The investigation of molecular interactions between a silica surface and organic/inorganic polymers is crucial for deeper understanding of the dominant mechanisms of surface functionalization. In this work, attachment of various depolymerized polydimethylsiloxanes (PDMS) of different chain lengths, affected by dimethyl carbonate (DMC), to silica nanoparticles pretreated at different temperatures has been studied using 29Si, 1H, and 13C solid-state NMR spectroscopy. The results show that grafting of different modifier blends onto a preheated silica surface depends strongly on the specific surface area (SSA) linked to the silica nanoparticle size distributions affecting all textural characteristics. The pretreatment at 400 °C results in a greater degree of the modification of (i) A-150 (SSA = 150 m2/g) by PDMS-10/DMC and PDMS‑1000/DMC blends; (ii) A‑200 by PDMS-10/DMC and PDMS-100/DMC blends; and (iii) A-300 by PDMS-100/DMC and PDMS-1000/DMC blends. The spectral features observed using solid-state NMR spectroscopy suggest that the main surface products of the reactions of various depolymerized PDMS with pretreated nanosilica particles are the (CH3)3SiO-[(CH3)2SiO-]x fragments. The reactions occur with the siloxane bond breakage by DMC and replacing surface hydroxyls. Changes in the chemical shifts and line widths, as shown by solid-state NMR, provide novel information on the whole structure of functionalized nanosilica particles. This study highlights the major role of solid-state NMR spectroscopy for comprehensive characterization of functionalized solid surfaces.

Anomalous Terminal Shear Viscosity Behavior of Polycarbonate Nanocomposites Containing Grafted Nanosilica Particles

Viscosity controls an important issue in polymer processing. This paper reports on the terminal viscosity behavior of a polymer melt containing grafted nanosilica particles. The melt viscosity behavior of the nanocomposites was found to depend on the interaction between the polymer matrix and the nanoparticle surface. In the case of polycarbonate (PC) nanocomposites, the viscosity decreases by approximately 25% at concentrations below 0.7 vol% of nanosilica, followed by an increase at higher concentrations. Chemical analysis shows that the decrease in viscosity can be attributed to in situ grafting of PC on the nanosilica surface, leading to a lower entanglement density around the nanoparticle. The thickness of the graft layer was found to be of the order of the tube diameter, with the disentangled zone being approximately equal to the radius of gyration (Rg) polymer chain. Furthermore, it is shown that the grafting has an effect on the motion of the PC chains at all timescales. Finally, the viscosity behavior in the PC nanocomposites was found to be independent of the molar mass of PC. The PC data are compared with polystyrene nanocomposites, for which the interaction between the polymer and nanoparticles is absent. The results outlined in this paper can be utilized for applications with low shear processing conditions, e.g., rotomolding, 3D printing, and multilayer co-extrusion.

Mechanical Behavior of Reinforced Silty Sand: Focus on Application of Nano-Silica or Kaolin Coated Ceramic Fibers as a Reinforcement Material

Many studies have been done on the stabilization of weak soil using conventional chemical stabilizers such as lime, cement as well as modern materials such as nanoparticles; however, very few studies have examined the effect of coated fibers on the strength of stabilized soil. This paper presents the results of a series of direct shear tests on soil specimens treated with ceramic fiber, nanosilica, and kaolin. The effects of ceramic fibers, fiber length, nanosilica, and kaolin on the mechanical characteristics and shear strength of silty sand was investigated. The results show that the addition of fiber to silty sand resulted in a significant increase in the strength of the soil specimens. The dilative behavior of the soil specimen decreased with the addition of ceramic fibers. The cohesion of the fiber-reinforced specimens increased when the fiber surface was coated with nanosilica or kaolin particles. The friction angle of the coated fiber-reinforced specimens decreased with the addition of nanosilica particles; however, the friction angle of the coated fiber-reinforced specimens was practically independent of the kaolin content.

Structurally Designed Imine Skeletal Pyrenyl Pendant Pyridine Core Polybenzoxazine nSiO2/PBZ Hybrid Polymer Nanocomposites

Novel polybenzoxazine-silica (nSiO2/PBZ) hybrid nanocomposites were designed and synthesized using carbazole terminal pyrenyl pyridine core imine skeletal benzoxazine monomer (PYCBZ) and nanosilica (nSiO2) through in situ sol-gel method. The FT-IR and Raman spectral studies ascertained the formation of nanosilica reinforced polybenzoxazine hybrid nanocomposites. The nSiO2/PBZ hybrid nanocomposites exhibited excellent thermal stability and higher char yield than that of neat PBZ. The elevation in glass transition temperature of the nanocomposites was evidenced by the limited motion of the polymeric network with the introduction of nanosilica particles in the PBZ matrices. The hydrophobic nature of a less polar nSiO2 in the composites zipped the water uptake behaviour of (nSiO2/PBZ) hybrid nanocomposites to low percentage. The shift in the absorption peak reveals that the nanosilica particles were successfully incorporated through thermal ring opening polymerization of benzoxazine. The homogeneous reinforcement of nSiO2 particles retains the fluorescent properties of polybenzoxazine. The uniform molecular level dispersion of nano SiO2 onto polybenzoxazine networks were confirmed from transmission electron microscope and scanning electron microscope images.

Electrical Treeing and Partial Discharge Characteristics of Epoxy/Silica Nanocomposite under Alternating Current

The hydrophilic surface of fumed nanosilica was modified to a hydrophobic surface by treating it with a trimethyl silane coupling agent, and epoxy nanocomposites were prepared by mixing the modified nanosilica (0 phr, 1 phr, 3 phr, 5 phr, and 7 phr) in an epoxy matrix, where the unit phr means the parts per one hundred grams of epoxy base resin. To apply the nanocomposites to heavy electrical equipment, the effects of the modified nanosilica on the long-term treeing phenomena and the partial discharge (PD) resistance were studied under high voltage alternating current (HVAC) conditions. The bonding of trimethyl silane on the nanosilica surface was confirmed by the appearance of new peaks for the CH2 and CH3 groups in Fourier-transform infrared spectroscopy analysis. To observe the even dispersion of the modified nanosilica particles in the epoxy matrix, a transmission electron microscope was employed, and it was found that 1 phr of the modified nanosilica was uniformly dispersed; however, as the nanosilica content was increased, its aggregation became somewhat severe. The longest HVAC treeing breakdown time was found in an epoxy nanocomposite with 1 phr of alkyl-modified nanosilica, and the time was 17,412 min, which was 143.9 times longer than the 121 min required for a neat epoxy system. In a nanocomposite with 5 phr of modified nanosilica, PD resistance was found to be 12.5 times higher than that of the neat epoxy system.

Effect of Nanosilica on the Mechanical Properties, Compression Set, Morphology, Abrasion and Swelling Resistance of Sulphur Cured EPDM/SBR Composites

The main objective of the current research work is to explore the effect of nanosilica particles on the compound EPDM/SBR-SiO2 (ethylene-propylene-diene monomer/styrene-butadiene rubber-nanosilica). The composite EPDM/SBR with and without silane coupling agent was processed using an open mill mixer. The nanosilica particles are prepared in the laboratory and were used as the reinforcing material in EPDM/SBR rubber composites. The cure characteristics, mechanical properties, hardness, rebound resilience, swelling resistance, abrasion resistance and compression set of the composites are completely analyzed and studied. Nanosilic particles are produced in the laboratory and used as reinforcement material in EPDM/SBR rubber compounds. Fully analyzed and examined are the cure characteristics, mechanical properties, hardness, rebound resilience, swelling resistance, abrasion resistance and compression collection of the composites. It was also evident from the result that with the inclusion of nanosilica particles in the EPDM/SBR rubber composites, the mechanical properties, swelling resistance, hardness, abrasion resistance and compression set properties improved.