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This investigation aims to figure out the contribution of nanoparticles graphene on the high-velocity impact performance and viscoelastic behavior of luffa cylindrica fiber (LCF)/Kevlar sandwich laminates. The epoxy matrix was altered through a mechanical stirring approach by adding varied wt% of the nanofiller graphene. The graphene-added Kevlar/LCF sandwich epoxy composites were created by hot pressing. The mechanical and viscoelastic performance of the sandwich composites was evaluated. The mechanical characteristics of the 3 wt% filler incorporated sandwich composites exceeded those of the control sample. The mechanical characteristics of the sandwich composites with 3 wt% filler incorporated showed improvements of 27.54%, 25.26%, and 26.05%, respectively, for (tensile, flexural and interlaminar shear strength) in contrast to the control sample. Morphological evaluation was executed on the samples being tested to determine the source of the breakage. The micrograph photographs revealed that the 3 wt% nanoparticles incorporated sandwich laminates had the best interfacial bonding and the least fiber disengagement. Dynamic mechanical analysis (DMA) was employed on the generated sandwich composites. The DMA findings revealed that sandwich laminates with 3 wt% nanoparticles responded with improved viscoelastic performance. The capability of the Kevlar/luffa fiber laminates using nanographene in addition to absorbing energy was assessed through a ballistic impact test. It was revealed that integrating nanographene into Kevlar/luffa sandwich composites enhanced their resistance to impact. It was seen from the ballistic impact tests that the presence of 3 wt% nanofiller resulted in substantial energy absorption. The composite sample with 3 wt% filler excels over the control sample by 68.80% in terms of energy absorption. In addition, the optimal wt% graphene nanofiller composite samples could be used to manufacture helmets for ground personnel due to their good mechanical and energy absorption capabilities. [ABSTRACT FROM AUTHOR]

Polystyrene (PS), a widely known amorphous, transparent, glassy, thermoplastic material, is one of the industrially significant polymers for its wide range of applications from packaging to commodity articles. PS is also well-known for its critical drawback of brittleness. This investigation aims towards improving the impact strength of PS by blending it with liquid isoprene rubber (LIR). PS/LIR compositions viz., 85/15, 80/20, 75/25 and 70/30 were mixed and dynamically vulcanized using Haake Rheomixer using sulphur-based vulcanizing system. The dynamically vulcanized blends were subjected to tensile, flexural and impact testing along with thermal and microscopic characterization. From the experimental data, it was evident that there was 110% increment in impact strength of PS matrix with the presence of 15% parts by weight of dynamically vulcanized LIR. The blend with 30% LIR content showed an increased thermal stability of matrix but with a reduction in tensile and flexural strength. The SEM image exhibited the dispersion of fine-sized spherical particles of LIR in PS matrix which is conducive in toughness enhancement. This study offers a novel approach in developing the TPV which is based on oligomer rubber. Also, it is energy efficient approach over solid elastomers. [ABSTRACT FROM AUTHOR]

Reactive melt mixing of recycled polyethylene terephthalate (r-PET) and recycled polycarbonate (r-PC) blends in presence of various concentration of Cobalt(II) acetylacetonate catalyst was studied to obtain optimum of catalyst content. r-PET/r-PC blends in presence of catalyst exhibit enhanced mechanical properties in comparison to without catalyst. XRD patterns reveals decreasing crystallite of samples also miscibility of blend will increase in presence of 0.1 wt.% of catalyst. Melt flow index (MFI) analysis demonstrated a decreasing in molecular weight with increasing catalyst concentration. Mechanical properties in samples contain 0.1 wt.% of transesterification catalyst are improved, in which Tensile analysis test showed an improvement in elongation at break, modulus and tensile strength of samples in comparison with r-PET/r-PC. Izod impact test showed that catalyst in blends caused higher impact strength in samples. [ABSTRACT FROM AUTHOR]

Engineering polymers are used in a multitude of load-bearing applications where structural integrity and long-term reliability are of the utmost importance. In this study, two different commercial composites (Durethan and Technyl) of polyamide-6 reinforced with 30 wt% of glass fiber were manufactured by injection molding and different hydration conditions were tested. All composites were characterized chemical and mechanically (tensile, flexural, impact and toughness). The fractured surface morphology was analyzed microscopically. According to the infrared spectra, the chemical structures of the composites were not altered by the hydration conditions tested and there were no significant effects on the degree of crystallinity of the samples evaluated. The toughness and impact tests evidenced that the best hydration condition was an immediate immersion, followed by the one performed after 24 h the injection, where for the impact resistance test the Durethan composites was 27.84% higher than Technyl. Wet Pack hydration method, showed similar behavior with samples that were not hydrated, exhibiting low toughness and impact resistance. In general, Durethan composites hydrated by immediate immersion showed the best mechanical performance, being the most suitable to be used in the industry as a stretcher junction component. [ABSTRACT FROM AUTHOR]

Computer-Aided Engineering (CAE) is currently a standard tool in the development process of automotive components. For thermoplastic parts, for example, the manufacturing process is usually simulated with injection moulding simulation software, whereas passive safety is simulated with explicit crash software. Today, these two computational methods are only linked in the simulation of fibre-reinforced thermoplastics, where process induced fibre orientation is used by crash simulation to predict mechanical properties. In this work, a computer-assisted engineering (CAE) product design workflow is proposed for high-fidelity performance predictions of unreinforced injection moulded components. This approach integrates material testing at the part level and injection moulding simulation (Moldflow), and subsequently imports these "as-moulded" simulation results directly into a finite element solver (LS-Dyna) for high-fidelity performance predictions. A newly developed dedicated computer application allows users to seamlessly use results from injection moulding simulations in crash simulations. The manufacturing boundary conditions that most influence the mechanical behaviour are combined through the thermomechanical indices (TMI) methodology and mapped onto each crash mesh element. Mathematical functions have been used to correlate the TMI to important mechanical properties of the moulded polymer. A user-defined material model can read those indices and translate them to local mechanical properties. To validate the method, different combinations of moulding conditions were selected to manufacture components that were subsequently subjected to impact tests. The mechanical response of the polymeric parts under crash was analysed by simulations and validated by experimental testing. A set of quasi-static (1 mm/s) and dynamic impact (3 m/s) tests were performed, and the force–displacement curves were both experimentally and numerically assessed. The simulations under quasi-static loads overestimate the attained peak force, but the overall material response (elastic and hardening) is very representative of the expected trend. In the case of dynamic loads, the crash simulations can predict realistically the overall force–displacement curves in complex moulded geometries. [ABSTRACT FROM AUTHOR]

The mechanical (flexural, tensile and impact) properties and water kinetic parameters of water-absorbed hard wood (mangrove) reinforced high-density polyethylene composites were evaluated as untreated and treated mangrove dust (MD). Samples were prepared by mixing high-density polyethylene (HDPE) with MD at 10, 20 and 30% by weight in a twin-screw laboratory compounder and injection moulded into dumb-bell and rectangular-shaped test specimens for flexural, tensile and impact tests. Samples were soaked in distilled water for 1440 h at room temperature and a relative humidity of ~ 65%. The flexural strength and modulus indicated that treated composites exhibited lower decrease in values than their untreated counterparts at water equilibrium points. The dry composites maintained higher values of tensile properties, notwithstanding the treatment. Scanning electron microscopy of impact fractured surfaces showed evidence of improved MD-HDPE interfacial adhesion of treated composites in both dry and water-absorbed conditions. The water kinetics parameters such as the diffusion, sorption and permeability coefficients further show that dry composites are more water-resistant than the wet composites. Overall, the treated composites at dry and moisture-saturated conditions indicated better mechanical and moisture stability than the untreated MD/HDPE composites. [ABSTRACT FROM AUTHOR]

Mangrove wood particle (MP) of size range 500–1000 microns was thermally modified under inert condition to avoid oxidation at 120 °C. The untreated and treated mangrove were compounded with high-density polyethylene (HDPE) at 10 wt%, 20 wt% and 30 wt% in an extruder with twin screw and injection-moulded into rectangular bar shapes for impact tests; fractured surfaces of impact specimens were examined. Also, the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were evaluated. The results of the impact tests showed that increase in fibre loadings gave rise to an increase in peak load and critical stress intensity factor while energy to failure and critical strain energy release rate decreased which signifies improvements in the toughness of the composites. Scanning electron microscopy images revealed that there is stronger adhesion between the HDPE matrix of treated MP than their untreated counterparts. A decrease in the degree of crystallinity (Xc) was noted in the DSC of all composites with treated composites showing higher values of Xc. TGA showed a slight increment in the degradation peak temperature (Tp) of treated MP and MP/HDPE composites. [ABSTRACT FROM AUTHOR]

Excellent cryogenic mechanical properties are urgently requested for the materials used in liquid oxygen environment. However, a DOPO-modified epoxy resin (EP-P), which was compatible with liquid oxygen, had no improved cryogenic mechanical properties compared with the pure epoxy resin (EP). Besides, its mechanical properties at room temperature (RT) were obviously decreased compared with EP. Thus, a novel epoxy-grafted polysiloxane (EGP) was synthesized by dimethyldimethoxysilane, dimethoxydiphenylsilane and 3-glycidoxy-propyltrimethoxysilane through co-hydrolytic condensation reaction. EGP was introduced into EP-P to improve cryogenic mechanical properties, especially toughness of EP-P. Tensile properties and fracture toughness of the DOPO/EGP-modified epoxy resin (EP-P/Si) at RT and liquid oxygen temperature (90 K) were investigated. Compared with EP, at RT, failure strain and KIC of EP-P/Si were increased by about 100% and 40%; at 90 K, the above two properties were increased by about 60% and 50%. Besides, EP-P/Si had almost same tensile strength with EP at both RT and 90 K. The results of the liquid oxygen mechanical impact test indicated that EP-P/Si was still compatible with liquid oxygen. XPS analysis showed that EP-P/Si had lower oxidation degree after the impact test compared with EP-P, indicating that liquid oxygen compatibility was enhanced. [ABSTRACT FROM AUTHOR]

Composites based on poly(methyl methacrylate), dimethyl itaconate matrix and alumina particles were prepared. Ferrous oxide-doped alumina particles (Al2O3 Fe) and commercial alumina nanoparticles (Al2O3 n) modified with (3-aminopropyl)trimethoxysilane (AM) and methyl esters of linseed oil fatty acids (biodiesel—BD) were used as reinforcement. The mechanical properties of the prepared composites, containing 1, 3 and 5 wt% of surface-modified alumina particles, are compared to a neat polymer matrix. The particles were characterized by single-beam Fourier transform infrared spectroscopy, thermogravimetry and differential scanning calorimetry. The mechanical properties of the composites were determined by micro-Vickers hardness and impact testing. The morphology of the surface of the composites exposed to cavitation was observed through a field emission scanning electron microscope. AFM analysis was used to compare surface features seen using the SEM and to interpret the surface degradation properties. The hardness, cavitation resistance and high-impact energy resistance of the composites are better in the case of AM surface modification of alumina fillers, but biodiesel modified particles have comparable mechanical properties and a stabilized Al–O–Si bond that could be important when a composite is exposed to humidity or a wet environment. [ABSTRACT FROM AUTHOR]

This experiment addresses the influence of fiber, nanocontent, surface treatment and compression pressure in natural frequency and damping factor of sisal/coir/alumina nanocomposites. Taguchi method and gray relational analysis were carried out for finding the optimized process parameter for this impact hammer test. Biosynthesized nanoalumina from neem leaf was applied as the filler. Grey relational grade concluded that sisal, coir wt with 20%, 15%, alumina nano % 2, NaOH treatment with 5% and compression pressure with 10 MPa as the optimized working condition for this whole vibration procedure. Lesser diameter of sisal (100–200 μm) than coir fiber makes sisal the vital role in the damping nature of hybrid composites than other factors. Lesser diameter makes wider interface making enhancement in the property. SEM testing was adopted after tensile, flexural and impact tests for determining fractured surface of natural composites. [ABSTRACT FROM AUTHOR]

Core–shell natural rubber (CSNR), or encapsulated NR, was obtained by admicellar polymerization of poly(methyl methacrylate)-co-poly(3-trimethoxy silylpropyl methacrylate) (PMMA-co-PMPS) covering onto the NR particles. The core–shell structure was clearly observed in TEM micrographs. The presence of siloxane crosslinks in the shell was confirmed by FT-IR spectra. The obtained CSNR (containing NR core 70.85 wt% and polymeric shell 29.15 wt%) at 1–10 wt% loading was used to improve toughness and mechanical properties of PMMA. SEM micrographs revealed that the CSNR had excellent compatibility and good interfacial adhesion to the PMMA matrix. The impact strength of CSNR-PMMA blends increased with CSNR content having the maximum at about 5.85 kJ/m2, which is 23% higher than neat PMMA (4.58 kJ/m2). The elongation at break clearly improved to the maximum at 5 wt% CSNR, and tensile toughness was about 219% higher than for neat PMMA, while elongation was about 91% higher than for neat PMMA. Several toughening mechanisms (rubber cavitation, plastic yielding of the matrix, and partial pull-out of rubber) appeared in the impact test, while the mechanisms for tensile toughening included rubber cavitation and crazing. [ABSTRACT FROM AUTHOR]

Tensile and impact properties of PP/SEBS- g-MA/WF composites up to wood flour volume fraction 0.31 are evaluated. Tensile modulus and strength increased while elongation-at-break and Izod impact strength decreased with increase in volume fraction of the filler (Φ). The crystallinity of PP enhanced with Φ. The tensile properties were compared with predictive theories. SEM studies indicated formation of stress concentration points around WF particles with only limited extent of adhesion which led to large decrease in elongation-at-break and Izod impact strength of PP. [ABSTRACT FROM AUTHOR]

Plywood sheets based on wood plastic nanocomposites were prepared using palm tree fibers (PTF) filled in polystyrene (PS) nanocomposites. The nanocomposite sheets were prepared using free radical polymerization of styrene monomer containing 60 % PTF and different nanosilica concentrations. The effect of coupling agent on the adhesion between PTF and PS/SiO nanocomposites and PTF was pronounced at low nanosilica concentrations. The results of the flexural strength, impact test, abrasion resistance, and water absorption were explained on the basis of the effect of coupling agent between PTF and nanocomposite resin. [ABSTRACT FROM AUTHOR]