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This research paper focuses on the use of solid biomass waste, specifically a combination of Polyalthia longifolia seed (PLSF) and graphite (GH) powder, as reinforcements in vinyl ester (VE) composites. The composites were produced via the hand layup method, with the filler concentration varying from 0 to 15 wt% of PLSF and 0–9 wt% of graphite. The objective was to examine the influence of the hybrid filler on the mechanical characteristics of the composites. The mechanical properties of composites prepared from P. longifolia seeds and graphite powder were experimentally characterized. These properties included tensile strength, flexural strength, impact resistance, and hardness. The hybrid composite had a maximum tensile strength of 48.4 MPa, and its tensile modulus was 1.66 GPa. The hybrid filler at 15% wt% of PLSF and 6% of graphite has the highest flexural strength, which is around 148 MPa. The ultimate impact strength and hardness were measured to be 41.3 kJ/m2 and 44.5, respectively, after the addition of 15 and 6 wt% of hybrid filler. In comparison to neat vinyl ester resin, the PLSF/GH‐VE composites exhibited an increase in tensile, flexural, impact, and hardness of 2.69, 1.82, 3.03, and 1.59 times, respectively. Hybrid composite surfaces were analyzed using scanning electron microscopes to determine surface characteristics and fractured surfaces. In addition, the PLSF/GH‐VE composites have been utilized in the production of components for four‐wheelers. Highlights: Investigated the impact of hybrid filler‐reinforced vinyl ester composites.Mechanical and thermal properties were experimentally characterized.Surface characteristics and fractured surfaces were examined.PLSF/GH‐VE composites are used in producing components for four‐wheelers. [ABSTRACT FROM AUTHOR]

In this work, this study aimed to overcome the inherent disadvantage of low thermal stability and brittleness of epoxy resins. A novel modifiers containing alkynyl‐ and allyla‐ groups, (E)‐1‐(4‐(allyloxy)‐3‐methoxyphenyl)‐N‐(3‐ethynylphenyl)methanimine (MNEM) was prepared and confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H‐nuclear magnetic resonance (1H NMR), and selected to improve the thermal stability and toughness of bisphenol A‐type epoxy resin (E51). The blend resins were produced by blending with different contents of MNEM into E51 resin, named E‐MNEM resins. Meanwhile, the thermal stability, mechanical properties, and micromorphology of E‐MNEM blends were analyzed in details. It was found that the thermal stability of E‐MNEM resins was improved by increasing the proportion of MNEM. Compared with E‐0MNEM resin, when the MNEM concentration reached 40 wt%, the char yield (Yc) increased from 14.95 to 29.62%, reflecting a 98.1% improvement. In addition, an appropriate concentration of MNEM could be conductive to improving the mechanical properties. An improvement of 25.5 and 7.1% in elongation and tensile strength along with the maximum value of 17.6 kJ/m2 for the impact strength was achieved by the cured E‐MNEM resins containing 20 wt% of MNEM. Finally, the fracture surface morphology of the E‐MNEM resins was analyzed by the scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

Cyanate ester (CE) resins possess excellent thermal and mechanical characteristics, yet their brittleness and high cross‐link density limit their practical application. To overcome this limitation, the modification of CE with thermoplastic resins has been employed as an effective strategy to enhance their toughness and mechanical properties. In this study, a novel fluorinated poly(aryl ether nitrile) (PFPEN) with excellent solubility and thermal properties was synthesized through a nucleophilic substitution reaction. The effect of the addition of PFPEN on a blend composed of bisphenol A cyanate ester (ACE) and a mixed catalyst was investigated. Differential scanning calorimetry results showed that the addition of PFPEN facilitated the curing reaction of ACE, resulting in a lower exothermic peak temperature. Compared to the pure ACE, the addition of PFPEN at 20 phr significantly improved the tensile and impact strengths of the resin, as well as enhanced the lap shear strength at room temperature by 36% and the peel strength by 320%, respectively. The scanning electron microscope results showed a ductile fracture mechanism. However, it should be noted that the decrease in crosslinking density resulting from the addition of PFPEN may affect the lap shear strength at 300°C and the glass transition temperature (Tg) of the material. [ABSTRACT FROM AUTHOR]

In this study, a novel biobased allyl compound with Schiff‐based structure (MPAM) was developed to improve the toughness and thermal properties of 4,4′‐bismaleimidodiphenylmethane (BDM). The chemical structure of MPAM was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR). A series of BDM/DBA‐MPAM blend resins (BD‐MPAM resins) were prepared by adjusting the mass ratio of BDM + DBA (BD) to MPAM. The effects of MPAM content on the curing behavior, thermal and mechanical properties of BD‐MPAM resins were discussed in details. Compared with BD resin, the thermal stability of modified resins was improved by increasing the content of MPAM. Meanwhile, an increase of 37.1% in flexural strength, and 228 MPa in flexural modulus were obtained for the cured BD‐MPAM resin having 10 wt% MPAM loading compared to the BD resin. The impact strength of BD‐10 wt% MPAM is of the maximum value (6.6 kJ/m2). Finally, the fracture surface morphology of the BD‐MPAM resins was studied by the scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

The need for eco‐friendly materials has been attracted due to renewability, abundance availability, low cost, and so on. Therefore, the search for bio fillers for the fabrication of bio‐based composite materials is gaining more and more attention in both academic and industry circles because it promotes sustainability. The present study represents the utilization of biomass solid waste in the hybrid form of Tamarind Seed and Date Seed Filler (TSF/DSF) into polymer reinforced composite which has been explored for the first time by a compression molding technique. These fillers are bio‐waste that can be obtained at a minimal cost from renewable sources. An attempt has been made to use these hybrid fillers to reinforce the matrix ranging from 0 to 50 wt%, and their physical, mechanical, and thermal properties were investigated. In general, the inclusion of hybrid fillers increases mechanical properties, although the addition of hybrid fillers had only a minor impact on thermal properties. When compared to the pure vinyl ester resin, the hybrid fillers reinforced composites revealed a significant enhancement in tensile, flexural, impact, and hardness properties, with improvements of 1.51 times, 1.44 times, 1.87 times, and 1.46 times respectively, at 10 wt% filler loading. Filler matrix interaction of fractured mechanical testing samples was evaluated by scanning electron microscope. Based on the findings, hybrid filler reinforced composites may be suitable for applications where cost is a consideration and where minor compromises in thermal qualities are acceptable. [ABSTRACT FROM AUTHOR]

Cyanate ester (CE) was employed to modify epoxy resin (EP) by chemical reaction, and the thermal, mechanical, and corrosion properties were systematically studied. Differential scanning calorimetry and Fourier transform infrared spectra were carried out to determine the curing kinetic parameters, suitable curing procedure, and reaction mechanism. The glass transition temperature and thermal stability were investigated employing dynamic mechanical thermal analysis and thermogravimetry measurement. Furthermore, the mechanical and corrosive properties were evaluated, using test techniques such as mechanical testing machine, abrasion tester, axle rod flexibility tester, scanning electron microscope, and electrochemical impedance spectroscopy. Results verified that an appropriate amount of CE could significantly improve the comprehensive performance of EP. However, a satisfactory effect would not be achieved when the modifier is inadequate or excessive. [ABSTRACT FROM AUTHOR]

Nanoparticles have been widely used in the improvement of the mechanical and thermal properties of the epoxy matrix. In this study, the room temperature curing agent composed of acrylic acid and 2,4,6‐trimethyl‐m‐phenylenediamine was mixed with different concentrations of CeO2 nanoparticles into the epoxy resin (E51) to obtain a nanocomposite that can be rapidly molded and cured. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to study the curing behavior of nanocomposites and E51 with the synthesized hardener. Through tensile, flexural, and impact tests, the influence of the nanoparticles content on the mechanical and thermal properties of the prepared composites was discussed. The results showed that the curing process was completed in 4 h. An increase of 78.4% in tensile strength, 81.7% in flexural strength, and 122.0% in elongation were obtained for the cured nanocomposite having 5 wt% CeO2 loading compared to the neat resin. Thermogravimetric analysis result showed that the thermal stability increased with increasing of CeO2 nanofillers content. Finally, the scanning electron microscope revealed the fracture surface morphology of the composites. [ABSTRACT FROM AUTHOR]

High‐performance composites reinforced with natural fibers are next‐generation structural materials due to their recyclability and light weight. Manufacturing composites with high strength has been a challenge. Here, we describe the manufacture of novel composites reinforced with wood fibers using densification by hot‐pressing and fixing by curing reaction with phenolic resin. This composite with 1.4 g/cm3 had high mechanical properties, high water stability, and aging‐resistance, and exhibited a flexural strength and internal bonding strength of 102.4 and 7.5 MPa, respectively. The strength and modulus are 1.5–6.0 and 1.3–28.1 times higher than those of most of the wood fibers reinforced composites. After immersing in water for 24 h, the water absorption and thickness swelling are only 1.3% and 0.8%, respectively. Scanning electron microscope characterization indicates that the cell wall is totally collapsed and became complete densification. And the collapsed cells are fixed by phenolic resin. This production strategy for the composites was shown to be universally effective for various species of natural fibers. These novel wood fiber‐reinforced composites were suitable for commercial manufacture in the current production line, making them a low cost and high‐performance alternative to automotive and aerospace industries. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) materials constituted by a microencapsulated paraffin having a melting temperature of 6°C and a thermoplastic polyurethane (TPU) matrix were prepared through fused deposition modeling. Scanning electron microscope (SEM) micrographs demonstrated that the microcapsules were homogeneously distributed within the matrix, with a rather good adhesion within the layers of 3D printed specimens, even at elevated concentrations of microcapsules. The presence of paraffin capsules having a rigid polymer shell lead to a stiffness increase, associated to a decrease in the stress and in the strain at break. Tensile and compressive low‐cycles fatigue tests showed that the presence of microcapsules negatively affected the fatigue resistance of the samples, and that the main part of the damage occurred in the first fatigue cycles. After the first 10 loading cycles at 50% of the stress at break, a decrease in the elastic modulus ranging from 60% for neat TPU to 80% for composite materials was detected. This decrease reached 40% of the original value at 90% of the stress at break after 10 cycles. Differential scanning calorimetry tests on specimens after fatigue loading highlighted a substantial retention of the original TES capability, in the range of 80%–90% of the pristine value, even after 1000 cycles, indicating that the integrity of the capsules was maintained and that the propagation of damage during fatigue tests took probably place within the surrounding polymer matrix. It could be therefore concluded that it is possible to apply the developed blends in applications where the materials are subjected to cyclic stresses, both in tensile and compressive mode. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to investigate octavinyl‐polyhedral oligomeric silsesquioxane (OV‐POSS) incorporation into natural rubber (NR)/butadiene rubber (BR) elastomer blends as a potential compatibilizer. The effects of OV‐POSS loading levels on the thermal, mechanical, morphological, and dynamic‐mechanical properties of elastomer blends were explored. Fourier‐Transform Infrared Spectrometer (FTIR), Temperature Scanning Stress Relaxation (TSSR), and Differential Scanning Calorimetry (DSC) results revealed the conceivable effect of OV‐POSS nanoparticles in the vulcanization through reacting with sulfur and/or elastomers. Scanning Electron Microscope (SEM), X‐Ray Diffraction (XRD), and tensile test measurements supported the improvement of mechanical properties due to homogeneous dispersion at low loading levels. On the other hand, high amount of OV‐POSS incorporation (7 and 10 phr) resulted in a decrease in mechanical properties, owing to the agglomeration of nanoparticles. According to contact angle and Dynamic mechanical analysis (DMA) results, it could be concluded that OV‐POSS nanoparticles were localized at the interface of the elastomers and enabled the compatibilization of immiscible NR/BR blends. [ABSTRACT FROM AUTHOR]

The first aim of this study was to compare influences of various contents of the micro‐ (200 nm) and nano (50 nm)‐sized titania (TiO2) particles especially on the mechanical performance of the polylactide (PLA) biopolymer. Micro‐ and nano‐composites were prepared by twin‐screw extruder melt mixing, while the specimens were shaped by compression molding. Scanning electron microscope analyses and mechanical tests revealed that due to the most efficient uniform distribution in the matrix, the best improvements in the strength, elastic modulus, and fracture toughness values could be obtained either by using 5 wt% micro‐TiO2 or by only 2 wt% nano‐TiO2 particles. The second purpose of this study was to investigate influences of using maleic anhydride (MA)‐grafted copolymer (PLA‐g‐MA) compatibilization on the performance of one nanocomposite composition. Due to the improved chemical interfacial adhesion, use of PLA‐g‐MA compatibilization for the specimen of PLA/2 wt% n‐TiO2 composition resulted in the highest improvements in the mechanical performance of neat PLA. The improvements were 14% in tensile strength, 20% in flexural modulus, and as much as 67% in fracture toughness. Thermal behavior of all specimens was also observed by differential scanning calorimetry and thermogravimetric analyses. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, copper (Cu) crystallites were successfully prepared via low temperature molten salt method, and the possible formation mechanisms were proposed. The conductive fillers of multiwalled carbon nanotubes (MWCNTs) and as-prepared Cu particles were designed and introduced into acrylonitrile-butadiene-styrene (ABS) blend to prepare different conductive composites. The dispersion states of conductive fillers and the morphologies of the composites were characterized using a field emission scanning electron microscope. The electrical resistivity of different composites was measured. The results showed that Cu and MWCNTs exhibited a synergistic effect in decreasing the electrical resistivity of the Cu/MWCNTs/ABS composites, because Cu that could locate between MWCNTs chain segments provides a better charge transport in the conductive pathways. Compared with pure ABS, the tensile strength, elastic modulus and thermal stability of the Cu/MWCNTs/ABS composites were significantly improved with the incorporation of Cu and MWCNTs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41738. [ABSTRACT FROM AUTHOR]

Nanocomposites of poly(vinylidene fluoride) (PVDF) with chemically reduced graphene nanosheets (GNs) were prepared by melt mixing method and their structure and morphology characterized by SEM analysis. The addition of GNs in the PVDF matrix resulted in changes of the crystallization and melting behaviors. Furthermore, increasing GNs content led to improved thermal stability of the PVDF nanocomposites in air and nitrogen, as well as significant increase in tensile and flexural properties. The nanocomposites' rheological behavior is also affected by the GNs' content. Using oscillatory rheology to monitor the GNs' dispersion, it was found that as the GNs loading increase, the Newtonian behavior disappears at low frequency. This suggests a viscoelastic behavior transition from liquid-like to solid-like, with greater GNs content and more homogeneous dispersion resulting in a stronger solid-like and nonterminal behavior. By using the melt mixing method to disperse GNs, the properties of PVDF are enhanced due to the better dispersion and distribution of GNs throughout the matrix. This improvement could broaden the applications for PVDF nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Three kinds of poly(urea-formaldehyde) (PUF) microcapsules filled with epoxy resins (MCEs) were applied to bismaleimide (BMI)/ O,O′-diallyl bisphenol A (BA) system to develop novel fiber reinforced BMI/BA/MECs composites. The effects of MCEs on the mechanical properties, the hot-wet resistance, and the dynamic mechanical properties of fiber reinforced BMI/BA composites were investigated. The morphologies of fiber reinforced BMI/BA/MCEs composites were characterized by scanning electron microscope (SEM) and optical microscope (OM). Results indicate that the appropriate contents of MCEs can significantly improve the mechanical properties and the hot-wet resistance of fiber reinforced BMI/BA composites. In this study, MCEs may decrease the storage modulus of fiber reinforced BMI/BA composite but they have no significant influence on the glass transition temperature ( Tg) of the composite. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The long‐term exposure to a hot and humid environment severely damages the bonding integrity of fiber‐reinforced polymer composites and thus significantly degrades their mechanical performances. In this work, we aim to develop an improvement procedure for effectively enhancing the bonding strength in glass fiber‐reinforced polymers (GFRPs). Glass fibers were coated with a thin layer of silica nanoparticles of different concentrations by the use of the evaporative deposition method. Micromorphological comparisons in terms of scanning electron microscope imaging demonstrate significant improvements on the surface roughness of glass fibers. With the coated glass fibers, GFRP composite laminates were designed, molded through the vacuum‐assisted resin infusion technique, and experimentally tested for quantitatively studying their hydrothermal aging performance. The water absorption tests conducted for three exposure temperatures suggest that both the water diffusion rate and the equilibrium water content can be effectively reduced due to the introduction of the silica coating. With increased exposure temperatures, however, the desired reductions become much less significant. A so‐called water‐channel diffusion mechanism along fiber/resin interfaces was proposed to explain the coupling effects of silica coating and exposure temperature. Reductions of water diffusion rate and equilibrium water content were expected to slow down the hydrothermal aging performance of GFRPs. For this purpose, both uniaxial tensile test and three‐point bending test were subsequently performed on GFRP specimens that have been subjected to different coating concentrations, exposure temperatures, and exposure durations. When compared with untreated GFRP specimens, both experiments demonstrate that the residual strength and stiffness can be effectively promoted through coating a thin layer of silica nanoparticles on glass fiber surfaces. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48652. [ABSTRACT FROM AUTHOR]

The influences of size and content of silicon dioxide (SiO2) nanoparticles on the morphological, optical, toughness, and thermal properties of polycarbonate (PC) were investigated. The PC nanocomposites were prepared using a twin‐screw extruder followed by injection molding. The scanning electron microscope (SEM) micrographs displayed an adequate level of nano‐SiO2 particle distribution within the PC matrix but still revealed some agglomerated particles. Upon increasing the content of nanoparticles, slightly larger agglomerates formed. These agglomerated particles caused a reduction in material transparency due to light loss via reflection and scattering. However, the incorporation of nano‐SiO2 into the PC matrix greatly improved toughness properties and slightly increased glass‐transition temperature (Tg), in conjunction with filler content (up to 4 vol %). This was particularly in the case with the smaller sized nano‐SiO2, which not only significantly improved toughness but also enhanced optical properties of the PC nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47634. [ABSTRACT FROM AUTHOR]