Increasing Weight Fraction Research Articles

Molecular dynamics simulation of salt diffusion in constituting phosphazene-based polymer electrolyte

A growing demand to visualize polymer models in liquid poses a computational challenge in molecular dynamics (MD) simulation, as this requires emerging models under suitable force fields (FFs) to capture the underlying molecular behaviour accurately. In our present study, we have employed TIP3P potential on water and all atomistic optimized potentials for liquid simulations FFs to study the liquid electrolyte behavior of phosphazene-based polymer by considering its potential use in lithium-ion polymer batteries. We have explored the polymer's local structure, chain packing, wettability, and hydrophobic tendencies against the silicon surface using a combination of a pseudocontinuum model in MD simulation, and surface-sensitive sum frequency generation (SFG) vibrational spectroscopy. The finding yields invaluable insights into the molecular architecture of phosphazene. This approach identifies the importance of hydrophobic interactions with air and hydrophilic units with water molecules in understanding the behavior and properties of phosphazene-based polymers at interfaces, contributing to its advancements in materials science. The MD study uniquely captures traces of the polymer-ion linkage, which is observed to become more pronounced with the increase in polymer weight fraction. The theoretical observation of this linkage's influence on lithium-ion diffusion motion offers valuable insights into the fundamental physics governing the behavior of atoms and molecules within phosphazene-based polymer electrolytes in aqueous environments. Further these predictions are corroborated in the molecular-level depiction at the air-aqueous interface, as evidenced from the OH-oscillator strength variation measured by the SFG spectroscopy.The fundamental findings from this study open new avenues for utilizing MD simulation as a versatile methodology to gain profound insights into intermolecular interactions of polymer. It could be useful in the application of biomedical and energy-related research, such as polymer lithium-ion batteries, fuel cells, and organic solar cells.

Surfactant-Polymer Complexation and Competition on Drug Nanocrystal Surfaces Control Crystallinity.

Nanosizing drug crystals has emerged as a successful approach to enabling oral bioavailability, as increasing drug crystal surface area improves dissolution kinetics and effective solubility. Recently, bottom-up methods have been developed to directly assemble nanosized crystals by leveraging polymer and surfactant excipients during crystallization to control crystal size, morphology, and structure. However, while significant research has investigated how polymers and other single additives inhibit or promote crystallization in pharmaceutical systems, there is little work studying the mechanistic interactions of multiple excipients on drug crystal structure and the extent of crystallinity, which can influence formulation performance. This study explores how the structure and crystallinity of a model hydrophobic drug crystal, fenofibrate, change as a result of competitive interfacial chemisorption between common nonionic surfactants (polysorbate 80 and sorbitan monooleate) and a surface-active polymer excipient (methylcellulose). Classical molecular dynamics simulations highlight how key intermolecular interactions, including surfactant-polymer complexation and surfactant screening of the crystal surface, modify the resulting crystal structure. In parallel, experiments generating drug nanocrystals in hydrogel thin films validate that drug crystallinity increases with an increasing weight fraction of surfactant. Simulation results reveal a connection between accelerated dynamics in the bulk crystal and the experimentally measured extent of crystallinity. To our knowledge, these are the first simulations that directly characterize structural changes in a drug crystal as a result of excipient surface composition and relate the experimental extent of crystallinity to structural changes in the molecular crystal. Our approach provides a mechanistic understanding of crystallinity in nanocrystallization, which can expand the range of orally deliverable small molecule therapies.

Effect of hybrid ratio and sintering temperature on hardness properties of hybrid AMCs

The present research work is aimed toward fabrication of hybrid Aluminium matrix composites (AMCs) of different hybrid ratios of Alumina (Al2O3) and Silicon Carbide (SiC) followed by investigation of their microstructure and hardness properties. Hybrid AMCs were fabricated through powder metallurgy process by adding 5 wt% and 10 wt% mixture of Al2O3 and SiC reinforcements of various hybrid ratios (0:1, 1:3, 1:2, 1:1, 3:1, 2:1 and 1:0) with the pure Aluminium powder. The mixture powder were properly mixed by ball milling arrangements for 6 h. The mixture powder were preheated at 500 °C for 2 h in a high temperature programmable tube furnace followed by immediate compaction under a closed die at 1500 psi pressure through automatic hydraulic press. The compacted specimens were then sintered at 350 °C, 500 °C and 650 °C for 2 h in the same furnace. Hardness test of the fabricated hybrid AMCs were carried out by Vickers Micro-hardness testers and hardness values were measured by the integrated software. The hardness properties of hybrid AMCs also were compared with the hardness properties of pure Aluminium specimens fabricated through the same process route and process parameters. It is interestingly observed that hardness of hybrid AMC is more when pure Aluminium powder is reinforced with only SiC of same wt.% for both the cases (5 wt% and 10 wt% reinforce AMCs) and it decreases with decrease of weight fraction of SiC and simultaneously increase of weight fraction of Al2O3 keeping total weight fraction of mixture as constant.

Properties of ultra lightweight foamed concrete utilizing agro waste ashes as an alkaline activated material

In the present investigation, rice husk ash (RHA), bamboo leaf ash (BLA) and palm oil fuel ash (POFA) known as agricultural-waste materials locally available were used to produce ultra lightweight foamed concretes (ULFCs). BLA, RHA, and POFA were used as replacements for cement in ULFCs at different weight percentages of 0 %, 5 %, 10 %, 15 %, and 20 %. To achieve the target density of 350 kg/m3, cement was substituted with agricultural wastes, and a protein foaming agent was added. The properties of ULFCs were examined including, slump test, setting time, fresh density, splitting tensile, compressive and flexural strengths, thermal insulating, microstructural and transport properties, permeability and pore's structure. The experimental results demonstrated that BLA and POFA ashes significantly outperforms in terms of efficiency and improved the mechanical and transport qualities of ULFCs than RHA ash. By increasing the weight fractions of BLA, RHA, and POFA from 5 % to 20 % in ULFC mixes resulted in an improvement in slump, porosity, capillary sorption, water absorption, bulk density, intrinsic air permeability, and specific heat. The ideal results were seen in terms of compressive strength, bending strength, splitting tensile strength, and UPV when 15 % POFA and BLA, and 10 % RHA were used as substitutes for cement. The increase in weight fraction of BLA, RHA, and POFA resulted in a rise in both thermal conductivity and thermal diffusivity of ULFCs. SEM studies revealed that incorporating different agricultural wastes positively affects the pore size distribution within the microstructure decreasing with increased content of ashes related to the development of ULFCs with stronger matrix. As a result, the formulated ULFCs met the masonry strength criteria while also providing economic and environmental benefits.

Dynamic responses of shear thickening fluid-filled lattice structures

Lattice structures that possess exceptional energy absorption capabilities show promise across various fields. However, their tendency to exhibit relatively low stiffness due to rotation or bending during impacts poses a challenge. Shear thickening fluid with the unique property of shear thickening effect can be an ideal filler to overcome the limitation of lattice structure. In this paper, composites that combined STF with new lattice structures were fabricated to investigate their dynamic response using experimental and numerical means and found that incorporating STF into these lattice structures not only preserved the inherent mechanical characteristics of the lattice structures but also led to substantial improvements on mechanical performance. The lattice structures displayed a noteworthy boost in stiffness, increasing significantly from 11.02 to 85.56 times. Additionally, there was an improvement in energy absorption, ranging from 2.78 to 5.51 times. These findings indicate that STF holds more promise in enhancing a structure's stiffness compared to its energy absorption capacity. Moreover, strain rate, weight fraction of STF, and cell size of the lattice structure were considered to further investigate their impact on the dynamic behaviour of STF-filled lattice structures. Our findings indicate that the increase in stiffness and energy absorption of the lattice structure following STF filling is correlated with an increase in strain rate and weight fraction but decreases when the cell size of the lattice structure is increased. The critical strain rate of STF-filled lattice structure was predicted, around 104 s−1, which indicates the onset of the shear-thickening effect in STF. Furthermore, it was observed that composites with higher weight fractions of STF were more responsive to changes in strain rate. Additionally, structures with initially lower mechanical properties experienced the most significant improvements after being filled with STF. These optimal outcomes provide valuable insights for the design of STF-filled lattice structures in practical applications.

Thermal performance enhancement of lauric acid using nanomaterials as composite phase change material.

In the present work, lauric acid was taken as a phase change material (PCM), and different nanoparticles (NPs) such as SiO2, TiO2, CuO, and ZnO were taken as the supporting materials. CuO NPs were prepared through the co-precipitation technique; SiO2, TiO2, and ZnO NPs were synthesized via the sol-gel technique. These NPs with different weight fractions were dispersed into molten lauric acid, individually. The variations in thermal properties (phase change temperature and latent heat for solid and liquid) of the prepared composite PCMs due to the dispersion of NPs were observed by DSC analyses. An increase in thermal conductivity of the composite PCMs was observed with the increasing weight fraction of NPs. In order to ascertain the long-term utility, a thermal reliability test was conducted on the composite PCMs with repeated heating and cooling cycles. Also, the specific heats of the pure PCM and the composite PCMs were determined as a function of temperature. Further, the experimental investigation was performed on the pure PCM and the prepared composite PCMs to assess their phase change behavior, and the test results clearly proved that the time required for the complete melting and freezing process of the composite PCMs was less when compared to pure PCM. By considering the above facts, the newly prepared composite PCMs can be recommended as a potential candidate for low-temperature solar heating applications.

Mechanical, and corrosive properties of AA7075 aluminium reinforced with rice husk ash particulates

The mechanical and corrosive properties of AA7075 alloy reinforced with rice husk ash (RHA) particles were studied. AA7075 matrix composite reinforced with varying percentage weight compositions of rice husk ash particles (5%, 10%, 15% and 20% wt) were prepared using stir casting technique. The mechanical, and corrosive properties of the new material were compared with that of the matrix alloy. The mechanical properties were also improved due to the automated stirring action employed during the casting process. AA7075-RHA composites had improved mechanical properties compared to the base matrix (AA7075). In terms of tensile strength there was an increase in this mechanical property with an increase in weight fraction of RHA particle (51% at 10% RHA), hardness (25.67% at 20% RHA), while for impact resistance, the reverse was the case as there was a 10.98% decrease in the resistance of the composite as the reinforcement fraction increased from 0%–20% RHA. The progressive decreases in the impact strength of the reinforced composite were probably due to agglomeration and non-homogeneity at higher reinforcements values. Corrosion experiments carried out showed improved properties in the reinforced composite compared to the unreinforced alloy, the corrosive properties improved with an increase in weight fraction of RHA in terms of weight loss (20.63% at 10% RHA), potentio-dynamic polarization (30.7% at 10% RHA) and open circuit potential (1.60% at 20%RH). The developed composite may be suitably applied in high-speed rotating shafts and automotive engineered brake parts.

Experimental Investigation on Effect of Weight Fraction of Sisal Fiber on Mechanical Properties of Sisal-E-Glass Hybrid Polymer Composites

Currently, hybridizing natural fibers with synthetic fiber is considered as the best solution for reducing the environmental pollution and the cost of materials. This is due to the lower mechanical properties and high water absorption capacity problems of natural fiber reinforced composites and nonbiodegradability and high-cost problem of synthetic fibers that can be solved by hybridizing them. This article aims to investigate the influence of the weight fraction of the sisal fiber on the mechanical property of the E-glass-sisal fiber reinforced epoxy matrix composite. The sisal fiber was treated by 8% sodium hydroxide (NaOH) for three hours. The samples of five different weight fractions of fibers (0%, 20%, 30%, 40%, and 60%) with a constant weight fraction of epoxy matrix (40%) were prepared as per the ASTM standard prepared by the manual hand layup method at room temperature. The tensile, compression, and flexural tests of the samples were carried out on the WP 310 universal testing machine. From the experimental results, it has been observed that the increasing weight fraction of the sisal fiber greatly influences the mechanical properties (tensile, compression, and flexural) of E-glass-sisal hybrid reinforced epoxy matrix composites. From all the tested samples, those consisting of 60% E-glass and 0% sisal fibers with 40% epoxy matrix showed better mechanical properties than other hybrid samples with tensile, compressive, and flexural strengths of 464.03 MPa, 40.1 MPa, and 239.06 MPa, respectively.

The effect of sawdust on the pore structure and properties of low-cost ceramic water filter materials

Low-cost ceramic water filters are a very effective point-of-use technology for removing bacteria and protozoa from drinking water. The filters are made from locally sourced clay and a porogen materials such as sawdust. It is recommended that the sawdust be sieved to 30-sieve (600 μm) to make reliable filters. However, the size distribution of sawdust is usually broad and can extend below 100 μm. This study divided 30-sieve sawdust into four narrower size distributions and made filter disks for measurement of hydraulic conductivity and bulk density. Additionally, the microstructure of the materials was examined in three dimensions by micro-CT. The results showed that, independent of sawdust particle size, the void volume fraction in the filter increased linearly with the weight fraction of sawdust. In contrast, the permeability coefficient increased non-linearly as the fraction of sawdust increased. The magnitude of the permeability was higher for the larger sawdust particles when the sawdust fraction was 10 wt% or higher. Three-dimensional imaging of the pore structure in the filters suggested that the non-linear increase in permeability with increasing weight fraction of sawdust may be associated with increased interaction of the cavities created by the sawdust.

Bending and buckling analysis of functionally graded graphene origami metamaterial irregular plates using generalized finite difference method

Bending and buckling behavior of graphene origami(GOri) metamaterial irregular plates (octagonal star plates, cordiform plates, a quarter of annular plates and a quarter of annular plates with a hole) under different boundary conditions are investigated based on the higher-order shear deformation theory. The metamaterial by adding GOri to copper matrix in the form of gradient arrangement as reinforcement material has the properties of negative Poisson's ratio (NPR) and compressive, flexural as well as fracture toughness beyond traditional materials that are independent of the topology/architecture of the structure. The governing equations of irregular plate structures are deduced with Hamilton’s principle. Generalized finite difference method, which is a meshless method based on Taylor series expansion and moving least squares approximation, is adopted to solve the numerical solutions. The accuracy and convergence of the proposed method are verified by numerical examples. Numerical experiments show that with the increase of GOri weight fraction, the central bending deflection of irregular plate structures decreases as the folding degree of GOri rises from 20% to 80% and the temperature changes from 300 K to 400 K, the opposite conclusions can be drawn for the buckling. The research on the bending and buckling behavior of irregular plate structures in this paper has important theoretical value for its future application in aerospace engineering field.

Acoustic Impedance Evaluation of the Polymer-Polymer Hybrid Composites as Insulator Building Materials.

Acoustic energy dissipates in multi-phase or multi-boundary materials. Hybrid composites are described as multi-phase with many interfaces between their materials. The current research proposes the study of the acoustic behavior of polymeric hybrid composites by estimating the time, velocity, and hybrid composite acoustic impedance. Two groups of hybrid composites were prepared, including unsaturated polyester with PMMA, except one with HDPE and the other with PS. Each group had 28%, 35%, and 40% weight fractions. An ultrasonic test measured the time to determine the velocity and then the acoustic impedance later. The results showed that increasing the weight fraction will increase the density with respect to the density of the reinforcing material. Different ultrasonic times were obtained with increasing weight fractions. As the weight fraction of PS increased, the time increased; unlike the velocity, it decreased but increased with density. In contrast, this behavior was changed if the hybrid had PE. The highest acoustic impedance was at 28% UP/PMMA + PS. In conclusion, UP/PMMA + PS can dissipate ultrasonic waves more than UP/PMMA + PE.

Influence of SiC nanoparticle contents on microstructural evolution and mechanical behavior of AZ91D magnesium matrix composites synthesised through a combination of a master pellet feeding technique and stir casting assisted by ultrasonic vibration

In this current study, an integrated approach involving a master pellet feeding technique and stir casting assisted by ultrasonic treatment processing was employed to fabricate AZ91D magnesium matrix nanocomposites reinforced with various concentrations of SiC nanoparticles (1.0, 1.5, and 2.0 wt%). The influence of the nanoparticle feeding method and the weight fraction of reinforcement on the microstructure and mechanical properties of AZ91D/SiC composites was thoroughly examined. The microstructural analysis revealed that the implementation of a master pellet feeding approach resulted in a relatively uniform dispersion of SiC nanoparticles within the primary α–Mg phase, whereas the original nanoparticle feeding method led to noticeable particle agglomeration in the microstructure. Additionally, with an increasing weight fraction of SiC nanoparticles, the primary α-Mg grain became finer and the β-Mg17Al12 intermetallic phase turned smaller. The hardness and tensile properties of AZ91D/SiC composites were significantly enhanced with increasing SiC contents. The addition of 2.0 wt% SiC reinforcements to the AZ91D magnesium alloy resulted in a maximal hardness increase of 41 %. Nevertheless, the ultimate tensile strength (UTS) and elongation (%EL) decreased when the SiC content exceeded 2.0 wt% due to the presence of increased porosity content and particle clusters in the microstructure. Notably, the AZ91D/1.5 wt% SiC composite exhibited promising tensile properties, with yield strength (YS), ultimate tensile strength (UTS), and elongation (%EL) values of 151 MPa, 192 MPa, and 4.54 %, respectively.

Acoustic Michelson interferometer based on a phononic crystal

A practical and highly sensitive acoustic Michelson interferometer with a small form factor is introduced. It involves two different types of phononic crystals composed of steel rods in water acting as a medium for self-collimated waves and mirrors for the reference and sample beams, as well as a beam splitter formed by modified scatterers arranged diagonally. Finite-element method simulations are employed to demonstrate its operation around 200 kHz. Equifrequency contour analysis reveals self-collimation of ultrasonic waves between 190 and 210 kHz. Introduction of the beam splitter and mirror phononic crystals is not detrimental to self-collimation where outgoing waves from the two interferometer arms interfere such that the output intensity varies in a cosine squared manner. Consequently, maximum sensitivity is achieved when the movable mirror displacement is either zero or half of the interferometer phononic crystal period. On small intervals in these ranges, micrometer-scale displacement resolution is achievable, as the output intensity drops by 0.2% per micrometer. Thus, displacements smaller than a percent of the wavelength are easily resolvable. Nanoscale resolution can be obtained with a scaled down interferometer design. Moreover, application to liquid concentration sensing by considering ethanol–water binary mixture is demonstrated. A percent increase in weight fraction of ethanol up to 10% in the mixture leads to an intensity drop as high as 2%. Thus, significantly higher sensitivities compared to sensing schemes based on resonance frequency shift are attainable. The proposed approach can be adapted for surface acoustic waves in strain measurement or biosensing.

Mechanical Behaviour of Polymer Matrix Composite Reinforced by Silicon Carbide Particles

In various fields, Polymer-based composites are used extensively instead of traditional materials. The hand lay-up technology has been employed to prepare the composites of Silicon carbide particles-epoxy. Mechanical properties; shore D hardness, Flexural strength, tensile strength and impact strength were measured for all specimens. The present work has also studied the impact of different weight percentages (including 3, 6, 9, 12, 15 and 18) wt.% of SiC solid powder on the mechanical properties of fabricated samples with two average particle sizes of 75 and 105 µm. SiC particles were utilized as reinforcement with the epoxy with hardener according to the mixing of (3:1) ratio. The experimental results found that hardness, flexural strength and impact strength can be increased by increasing the weight percentage of Silicon carbide, while tensile strength is decreased with an increased weight fraction of silicon carbide. At the same time, these properties were enhanced when the particles of SiC have 75 µm more than at 105 µm.

Influence of Lyophilization and Cryoprotection on the Stability and Morphology of Drug-Loaded Poly(ethylene glycol-b-ε-caprolactone) Micelles.

Polymeric micelles are promising carriers for the delivery of poorly water-soluble drugs, providing enhanced drug solubility, blood circulation times, and bioavailability. Nevertheless, the storage and long-term stability of micelles in solution present challenges requiring the lyophilization and storage of formulations in the solid state, with reconstitution immediately prior to application. Therefore, it is important to understand the effects of lyophilization/reconstitution on micelles, particularly their drug-loaded counterparts. Herein, we investigated the use of β-cyclodextrin (β-CD) as a cryoprotectant for the lyophilization/reconstitution of a library of poly(ethylene glycol-b-ε-caprolactone) (PEG-b-PCL) copolymer micelles and their drug-loaded counterparts, as well as the effect of the physiochemical properties of different drugs (phloretin and gossypol). The critical aggregation concentration (CAC) of the copolymers decreased with increasing weight fraction of the PCL block (fPCL), plateauing at ~1 mg/L when the fPCL was >0.45. The blank (empty) and drug-loaded micelles were lyophilized/reconstituted in the absence and presence of β-CD (9% w/w) and analyzed via dynamic light scattering (DLS) and synchrotron small-angle X-ray scattering (SAXS) to assess for changes in aggregate size (hydrodynamic diameter, Dh) and morphology, respectively. Regardless of the PEG-b-PCL copolymer or the use of β-CD, the blank micelles displayed poor redispersibility (<10% relative to the initial concentration), while the fraction that redispersed displayed similar Dh to the as-prepared micelles, increasing in Dh as the fPCL of the PEG-b-PCL copolymer increased. While most blank micelles displayed discrete morphologies, the addition of β-CD or lyophilization/reconstitution generally resulted in the formation of poorly defined aggregates. Similar results were also obtained for drug-loaded micelles, with the exception of several that retained their primary morphology following lyophilization/reconstitution, although no obvious trends were noted between the microstructure of the copolymers or the physicochemical properties of the drugs and their successful redispersion.

Size-effect testing: Nano-alumina enhances fracture toughness of epoxy resins

Epoxy resins are widely used as matrix in fiber-reinforced composites. We investigate how adding nano-alumina affects the mechanical strength of epoxy resins. Size-effect testing is used to determine the fracture toughness of epoxy resin samples with 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% weight fraction. For each weight fraction, the measured strengths follow type-II energetic strength scaling law. With increasing weight fraction, the fracture toughness rose monotonically from 1.48 MPam to 2.43 MPam, a 64% increase. The fracture process zone size(FPZ) also increased monotonically from 0.28 mm to 0.93 mm. Larger FPZ at higher weight fractions is associated with more distributed cracking and higher energy dissipation. These results show the toughening effect of the nano-alumina on epoxy resins. Field Emission Scanning Electron Microscope (FESEM) images of failed specimens showed formation of nano-alumina agglomerates at higher weight fractions. However, these agglomerates have no adverse effect on strength for the weight fractions considered.

Effect of PbO Incorporation with Different Particle Sizes on Structural and Mechanical Properties of Polystyrene

Abstract Two different sizes of lead oxide (PbO) nanoparticles, notably PbO(A) and PbO(B) with sizes of 78 and 54 nm, respectively, were produced using a high-speed planetary ball milling machine under specific operating parameters. Following this, the novel polystyrene (PS) nanocomposite PS/PbO was prepared using compression molding by embedding 10, 15, 25, and 35 wt. % of PbO(Bulk), PbO(A), and PbO(B) into PS separately. The composite was further characterized by Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and laser-induced breakdown spectroscopy (LIBS). FTIR results confirmed the presence of PbO and indicated physical adsorption of the nanoparticle onto the PS matrix surface. SEM, EDS, and LIBS analyses revealed a more efficient diffusion of PbO in the PS matrix with the decrease of the nanoparticle size. On the other hand, tensile and Vickers microhardness tests were performed to investigate the composite’s mechanical properties. The stiffness was, indeed, enhanced with increasing weight fraction as well as with decreasing particle size of PbO. The strength of the composite was optimized with 15 wt. % of PbO. The microhardness test revealed an indentation size effect behavior of the composite and an increase in Hv values with PbO loads up to 15 wt. %. Accordingly, by adjusting the filler particle size and concentration, the mechanical properties of the composite were enhanced, increasing their use in a variety of applications such as coating, insulation, and radiation shield.

Effect of carbide ceramics and coke on the properties of dispersion strengthened aluminium‐silicon7‐magnesium hybrid composites

AbstractIn this study, aluminium‐silicon7‐magnesium alloy was reinforced with carbide ceramics (silicon carbide and boron carbide) and coke microparticles. The composite samples (S1, S2, and S3) with 4 %, 8 %, and 12 % by weight of silicon carbide and boron carbide microparticles and 8 % by weight of coke micro particles respectively, were prepared through the ultrasonic assisted melt‐stir casting route. It was observed from the literature that only a few research works reported the cumulative effect of adding these micro‐particulate reinforcements within aluminium‐silicon7‐magnesium alloy. The microstructural evaluation revealed uniform dispersion of particulate reinforcements. Area energy dispersive x‐ray spectroscopy scan results proved the presence of the reinforcement particles as heterogeneous phases at distinct zones. The samples undergone tensile tests failed under the brittle fracture mode. The ultimate tensile strength of the composites improved by about 27.4 %, the % elongation improved by about 6.8 %, and Vickers microhardness dropped 1.9 % to the maximum. Dimples were observed in the fracture morphology analysis and it was mainly due to the mixed ductility of the sample S2. An abrasive wear mechanism was observed in the worn‐out sample S2. The wear rate decreased significantly with an increase in weight fraction of the reinforcements.

Effect of ocean water absorption on flexural properties of Cannabis sativa L. hemp fibre reinforced polymer composites for marine applications

Hemp is one of the strongest and most durable commercially available natural fibre. Its biodegradability, low density, high fibre length, availability, low weight-to-strength ratio and more yield per acre makes it an ideal fibre for marine applications. Water absorption behaviour of any material is very important which mainly limits their use specifically in marine applications. The present work aims to study the absorption of ocean water, its kinetics and effects on the flexural properties of hemp reinforced composites. Absorption effects for epoxy and unsaturated polyester (UPE) reinforced with short hemp fibre, unidirectional and bidirectional hemp fabric were investigated by immersing samples in ocean and distilled water. The absorption of all composites followed Fickian diffusion with slight deviation due to swelling of fibres and formation of microcracks. It is observed that the water uptake of samples increased with increasing weight fraction. The flexural strength and modulus of composites degraded by approximately 10% and 20% for epoxy and UPE composites respectively, due to water absorption. The results indicated that hemp fibre based composites could be used for many lightweight components in marine applications.

Bending electromechanical actuation mechanism and properties of nanostructured dielectric poly (styrene-b- (ethylene-co-butylene)-b-styrene) / white mineral oil (SEBS/WO) blend elastomers

Dielectric elastomers (DEs) as one class of electronic type of electroactive polymers (EAPs) can be deformed under electrical stimulation, and have important applications in the soft robots, wearable electronic devices, and medical rehabilitation machinery so on. In this work, the bending actuation mechanism, and electromechanical properties of nanostructured dielectric poly (styrene-b-(ethylene-co-butylene)-b-styrene)/white mineral oil (SEBS/WO) blend films were investigated under free electrodes condition. The morphology and mechanical properties of SEBS/WO films were adjusted by the content of WO, where the WO selectively swelled the poly (ethylene-co-butylene) (PEB) domains. The phase transition of lamellar (LAM) structure to hexagonal array packed cylinder (HEX) of SEBS/WO films was observed when added WO content larger than 17 wt%. The modulus and the polystyrene (PS) domain radius of SEBS/WO blend films with HEX structure were decreased as increase of WO weight fraction. The bending displacement of SEBS/WO films was almost linearly dependent on the applied electric voltages, and the single cantilever model based calculated bending force was almost linearly dependent on inverse of PS domain radius for SEBS/WO films with HEX morphology. The bending actuation mechanism of SEBS/WO films with HEX morphology was suggested that the bending actuation of SEBS/WO films was caused by electrostatic attraction force between inter-PS domains induced squeezing deformation of poly (ethylene-co-butylene) (PEB) domains. The SEBS/WO blend films with 50 wt% of WO content showed 6.54 mm (corresponding to 23.56°) at 2 kV (50 V/mm of nominal electric field). Our results can provide new insight on development of nanostructured electroactive elastomers for applications in the soft actuator materials.