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Composites are fabricating by reinforcing waste bambara nut shell powder (BNSP) as a bio-filler into an epoxy resin matrix. The composite is fabricated by varying the mass fractions of filler in the range of 5–35 wt%. The effects of bio-filler content on physical, mechanical, and thermal properties are evaluated. The studies reveal that the tensile strength, tensile modulus, flexural strength, and impact strength increased with increasing bio-filler content. The highest mechanical properties of BNSP-loaded epoxy composites are achieved at bio-filler mass content of 15 wt%, whereas hardness increased for 5–35 wt% with peak value at 35 wt%. The water absorption and thickness swelling of the BNSF/epoxy composites increased with increasing bio-filler contents, while the density decreased with an increase in bio-filler content. The TGA results revealed that an increasing bio-filler content decreased thermal stability, whereas the Tg and Tm of the composites increased with increasing bio-filler content. [ABSTRACT FROM AUTHOR]

The present study explores the influence of Cobalt oxide nanoparticles(Co3O4 NPs) on the physicochemical characteristics of Poly(vinylalcohol)/ Chitosan (PVA/Cs) blend. Using a variety of techniques, the pure blend and the nanocomposites' composition, structure, optical, thermal, and mechanical properties, and antibacterial activity were characterized. The Co3O4 NPs were produced by precipitation method utilizing cobalt salt as the raw material. The crystalline nature of the nanoparticles and semi-crystalline behavior of the PVA/Cs are demonstrated by the XRD data. Adding nanoparticles to the pure blend reduced the intensity of the semi-crystalline. The rise in absorption intensity observed in UV-visible spectra upon the incorporation of Co3O4 NPs into the PVA/Cs blend indicates an improved dispersion of the nanoparticles within the blend. When Co3O4 NPs are added, the energy band-gap Egdir and Egind of PVA/Cs–Co3O4 samples greatly decrease. According to TGA data, the thermal stability of nanocomposites was significantly higher than that of the PVA/Cs blend, and it rose as the concentration of nanoparticles increased. When compared to neat PVA/Cs film, mechanical property investigation of PVA/Cs–Co3O4 nanocomposites films revealed enhanced features. The effectiveness of the PVA/Cs–Co3O4 nanocomposite films in inhibiting the growth of microorganisms was assessed by evaluating their antimicrobial activity (ANMAC) against a range of bacteria and fungi. The inclusion of Co3O4 NPs led to an increase in activity against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria as well as fungi Candida albicans and Aspergillus niger (C. albicans and A. niger). The addition of Co3O4 NPs to the PVA/Cs blend effectively improved the material's optical, thermal, mechanical, and antibacterial properties. This remarkable improvement stems from the Co3O4 NPs, which were introduced into the PVA/Cs blend in different amounts, leading to the development of novel nanocomposites. The outstanding properties of Co3O4/PVA/Cs nanocomposite films suggest their potential for applications in optoelectronics and food packaging. [ABSTRACT FROM AUTHOR]

In this study, poly(l-lactide-co-ε-caprolactone) (PLCL) block copolymers with an ABA structure were prepared using a two-step polymerization process, and their microstructures, thermal, and mechanical properties were systematically investigated based on the introduction of ε-caprolactone as a comonomer in the first step to form the B block. As a result, it was observed that as the content of the B block, or the ε-caprolactone comonomer increased, the average sequence length of l-lactide decreased, indicating that a potential impact on the crystallization behavior and thermal properties of the final PLCL block copolymers. However, the decrease in thermal properties, such as the melting temperature, was less significant than expected. For instance, the melting temperature of pure PLA in this study was 172.5 °C, whereas the PLCL block copolymer with 9 mol% ε-caprolactone comonomer had a melting temperature of 171.1 °C, showing a relatively minimal difference between the two samples. Additionally, as the ε-caprolactone content increased, tensile strength and initial modulus of the PLCL block copolymer slightly decreased, while the breaking strain significantly increased. This suggests that the two-step polymerization method proposed in this study is effective in imparting flexibility to PLA while minimizing its mechanical property degradation. Consequently, the introduction of comonomer such as the ε-caprolactone through controlled polymerization process offers valuable insights for developing PLA materials with diverse properties. [ABSTRACT FROM AUTHOR]

This study reports the design and preparation of thermoplastic polyurethane (TPU), TPU/Cloisite 30B (0.4, 0.8, and 1.2 wt %) nanocomposites, and TPU/Irganox 1010 (0.5, 1, and 1.5 wt%) through a semi-batch method in an internal mixer and glass reactor. For this purpose, poly (ethylene adipate) was reacted with 4,4'-methylene diphenyl isocyanate to obtain the prepolymer and subsequently cured with 1,4-butanediol (BD) as chain extender to obtain the TPU sample. To accurately evaluate the curing reaction time (6 min), samples were taken from the internal mixer at specified intervals and then subjected to ATR-FTIR analysis (at 2, 4, and 6 min). Good distribution and dispersion of nanoclays in the resulting TPU nanocomposites were confirmed by XRD and scanning electron microscopy. Thermogravimetric analysis showed that the T5% and T50% of the TPU nanocomposite (TPU/Cloisite 30B (1.2 wt%)) were 15 and 33 °C higher compared to TPU-Internal. Similarly, the tensile strength of the TPU nanocomposite (TPU/Cloisite 30B (1.2 wt%)) was improved by about 25% compared to TPU-Internal. DMTA analysis revealed that the tan δ was decreased due to steric hindrance of Irganox 1010 on TPU chain mobility. Additionally, the tanδ peak for TPU-Internal was shifted from − 5.35 °C to 7.10 °C and − 1 °C for TPU 6 and TPU 3, respectively. [ABSTRACT FROM AUTHOR]

The promotion of different properties of polymers has become a substantial worldwide objective for different counterparts in industry and academia. In this work, different loadings of multi walled carbon nanotubes (MWCNTs) were employed to reinforce acrylonitrile butadiene styrene (ABS) to prepare polymer nanocomposites. The employed loadings by solution blending approach were (0.1, 0.5, 1.0, and 5.0) wt. %. FTIR and XRD were utilized to investigate the chemical interaction and crystal structure; respectively. The morphological investigation performed by scanning electron microscopy (SEM) showed the nature of the neat polymer, the dimensions and orientations of the nanotubes, and the good dispersion of the nanotubes within the polymer for the loadings up to 1.0 wt. %. As a result of this good dispersion, thermal properties represented by thermal degradation temperature (Td) and glass transition temperature (Tg) were improved. Furthermore, Young's modulus and tensile strength for the nanocomposite of 1.0 wt. % were enhanced by 87% and 46%, respectively as compared to the neat polymer. [ABSTRACT FROM AUTHOR]

Al–Zn–Mg–Cu alloys have been prepared using the gravity die-casting process. The influence of copper addition on microstructure, mechanical and thermal properties are studied. The experimental alloys were prepared using 5754 alloys, Al–Cu alloys, and pure zinc (solid form). Alloys are mechanically stirred for uniform distributions of alloying elements and precipitate phases. Four alloys with different copper weight percentages (0.02 wt%, 0.89 wt%, 1.57 wt%, and 3.34 wt%) were prepared. The α-Al and η (MgZn2) phases are observed in as-cast Al–Zn–Mg alloy. The addition of copper in Al–Zn–Mg alloys formed a θ phase (Al2Cu). Micro-Vickers hardness of Al–Zn–Mg–Cu alloy increased (from 116 HV1 to 133 HV1) with copper addition (0.02–1.57 wt%) at firstly due to the formation of θ phase (Al2Cu). Then, micro-Vickers hardness decreases due to high amounts of precipitates. Copper addition reduces the melting point (623–612 °C) and precipitation temperature (472–466 °C) of aluminum alloy. Al–Zn–Mg alloys have tensile strength of 422 MPa due to precipitates phase formation of η and T phases, solid solution strengthening (zinc and magnesium). Copper addition increases tensile strength due to the formation of θ phases. After achieving a strength of 486 MPa at an elongation of 3.72% (1.57 wt% Cu), tensile strength reduces due to a higher amount of precipitates. [ABSTRACT FROM AUTHOR]

SiO2f/SiO2 composites were prepared by compression molding and sintering using short-cut quartz fibers as reinforcement. The effects of fiber volume fraction (15%∼35%) on bulk density, apparent porosity, and mechanical and thermal properties of the composites were investigated. The results indicated that the samples with 25% fiber volume fraction had the best comprehensive performance, with an apparent porosity and compressive strength of 36% and 46.3 MPa, respectively. The flexural strength of the samples was 13.9 MPa, which represented a 90% increase compared to the samples without fibers. It was attributed to the occurrence of fiber debonding and fiber pull-out in the porous matrix. Meanwhile, the residual strength ratio of the samples after 20 thermal shocks was 74.8%. In addition, the average coefficient of thermal expansion was 0.95 × 10− 6/℃ at 300 ℃∼700 ℃ and the thermal conductivity was 0.388 W·m− 1·K− 1 at 800 °C. This approach can satisfy the requirements of low cost, fast preparation of SiO2f/SiO2 composites, which offers the prospect of its application in the integration of load-bearing and thermal insulation. [ABSTRACT FROM AUTHOR]

The effect of T4 and T6 treatment on the microstructures, precipitates, thermal expansion and thermal conductivity properties of Mg-2Nd-4Zn alloys was systemically investigated. The number of NdZn2 phase increased subjected to T6 treatment. The coherent relationship between the NdZn2 phase and Mg matrix was observed in the Mg-2Nd-4Zn alloys, which plays a great influence on improving the thermal expansion, thermal conductivity and mechanical properties of Mg-2Nd-4Zn alloys. The decrease in the coefficient of thermal expansion (CTE) and the thermal conductivity of Mg alloys were ascribed to the existence of solute atoms in alloys after the T4 treatment. It was also found that the T6-treated alloy has smaller area of the hysteresis loop, which has better thermal stability. Therefore, the high performance was mainly due to T6 treatment, the thermal conductivity of T6-treated Mg-2Nd-4Zn alloy is 124.4 K·m−1·K−1 at room temperature, and TYS of 235.5 MPa, CYS of 393.7 MPa, elongation of tension and compression are 31 and 27%, respectively. [ABSTRACT FROM AUTHOR]

The laser powder bed fusion (LPBF) process can integrally form geometrically complex and high-performance metallic parts that have attracted much interest, especially in the molds industry. The appearance of the LPBF makes it possible to design and produce complex conformal cooling channel systems in molds. Thus, LPBF-processed tool steels have attracted more and more attention. The complex thermal history in the LPBF process makes the microstructural characteristics and properties different from those of conventional manufactured tool steels. This paper provides an overview of LPBF-processed tool steels by describing the physical phenomena, the microstructural characteristics, and the mechanical/thermal properties, including tensile properties, wear resistance, and thermal properties. The microstructural characteristics are presented through a multiscale perspective, ranging from densification, meso-structure, microstructure, substructure in grains, to nanoprecipitates. Finally, a summary of tool steels and their challenges and outlooks are introduced. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of the addition of hexagonal boron nitride (hBN) and/or graphene nanoplatelets (GnP) to basalt fiber (BF)-reinforced polyphenylene sulfide (PPS) matrix composites at different weight ratios, both alone and hybrid, on the composite properties. Mechanical, tribological, thermal, and thermomechanical properties of the composites were evaluated using analyses such as tensile test at different ambient temperatures (23 °C and 70 °C), adhesive wear test, thermogravimetric analysis, differential scanning calorimeter analysis, and dynamic mechanical analysis. The results of the tensile test at 70 °C showed that the addition of 0.3 wt% GnP and 1 wt% hBN to the BF-reinforced composites resulted in a 40% increase in tensile strength. In addition, the composite containing 0.3 wt% GnP and 10 wt% hBN showed a 25% increase in high-temperature tensile strength, a 37% decrease in COF value, and a 10 °C improvement in T40% thermal decomposition temperature. Furthermore, the analysis results showed that the hybrid inclusion of GnP and hBN to the BF-reinforced PPS matrix composites improved the high-temperature tensile strength, adhesive wear resistance and thermal resistance properties. As a result, it is concluded that the hybrid use of GnP and hBN provides superior properties to the composites for advanced composite applications where mechanical, tribological and thermal performance is required along with electrical properties. [ABSTRACT FROM AUTHOR]

This study explored the effectiveness of hardened epoxy containing pear cactus fiber and onion sheath biocarbon nanosheet. Mechanical, dielectric, and thermal properties of pear cactus epoxy composites containing varying volumes of biocarbon nanosheet are the focus of this investigation. For this study, biocarbon was extracted by pyrolysis from red onion peel. For 3 vol.% of biocarbon, tensile strength was up to 63%, and flexural strength was up to 44% higher than pure epoxy. The addition of reinforcements boosted the Izod impact toughness and hardness values by around 5 volume percent to roughly 94% and 92%, respectively. When biocarbon made up 5% of a material's volume, improvements in dielectric constant and loss were around 5.8 and 0.23, respectively. The inclusion of biocarbon increased the thermal conductivity to a high of 0.44 W/mK. These composites might be used as a shielding material because to their improved dielectric, mechanical, and thermal activities. [ABSTRACT FROM AUTHOR]

A hybrid polymer nanocomposite polystyrene-b-poly(ethylene-ran-butylene)-b-polystyrene-grafted maleic anhydride with organically modified montmorillonite; SEBS-g-MA/OMMT was synthesized through solution casting methodology with varying clay proportions. The organophilic character was introduced into the inorganic clay platelets using 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPPP) as an intercalating mediator employing ion interchange process which was confirmed by XRD patterns. Nanocomposite films were investigated by FTIR, XRD, and SEM for their morphology. XRD pattern of the nanocomposite film revealed the homogeneous dispersion of platelets into the matrix, thus responsible for the improved material properties. Enhanced forces of adhesion led to a compatibilized system as depicted by scanning electron micrographs. Fine dispersion and smooth surface particles were exfoliated and were unidentified under the microscope. SEBS-g-MA showed improved mechanical strength up to 8% clay content based on tensile tests. When the mechanical strength of the nanocomposite was examined with its clay content, a 90% increase in modulus was found when compared to the original polymer matrix. Thermal decomposition temperatures of the nanocomposite ranged from 365 to 446 °C. With increasing clay loading, the nanocomposite exhibited thermal stability greater than pure polymers under similar conditions. [ABSTRACT FROM AUTHOR]

Linear low-density polyethylene (LLDPE) is a type of plastic with a high percentage of solid waste and is hardly degradable. The characteristics of LLDPE such as high toughness and low density have the potential to be an alternative aggregate substitute for applications in non-structural mortar composites. The purpose of this study was to determine the suitable formulation of LLDPE aggregate substitution against silica sand for the application of non-structural adhesive mortar composites. Vinyl acetate/ethylene (VAE) surfactant (1.2 wt%) was used to improve the interface between LLDPE and the cement matrix. Mechanical testing; XRD and FTIR characterization; density measurements; compression, adhesion, and thermogravimetric test; and morphological observation were carried out in this experiment. The results showed that LLDPE substitution decreased physical properties and accelerated thermal degradation. Cracks occurred on higher amount of LLDPE composition due to big difference in polarity. Suitable LLDPE substitution composition for adhesive mortar is up to 50%. [ABSTRACT FROM AUTHOR]

The increased interest in the use of polymer composites with natural, biodegradable and renewable fillers is the result of increased awareness of the environment. Therefore, the search for new materials that meet the above expectations is becoming a current issue. The article presents the results of research on composites containing pistachio shells (Pistacia vera L.), which are common agricultural waste, with unsaturated polyester resin based on post-consumer recycled poly(ethylene terephthalate) and vinyl ester resin based on bisphenol-A. The environmentally friendly polymeric cobalt solution was used as the accelerator. In order to study the degradation of the composites, accelerated ageing, immersion in various solvents, and high temperature were used. From the obtained results, it can be observed that accelerated aging resulted in the additional cross-linking of the resin, while the filler absorbed the UV light. During immersion, the polymer matrix was degraded in acetone, whereas the incorporation of pistachio increases its water sorption and the plasticisation effect was also observed. The alkali environment initiated the hydrolysis of ester linkages. The vinyl ester resin-based materials were more chemically and thermally resistant than those from the unsaturated polyester. [ABSTRACT FROM AUTHOR]

The scope of the work is to develop in-organic–organic hybrid epoxy nanocomposites using a combination of DGEBA (CY 230) epoxy resin and areca fibre (Af) mixture in the ratio of 70:30, respectively. The mixture was reinforced with varying weight percentages (1 and 2 wt%) of surface-modified nanozinc oxide (M-nZnO) and cured with triethylene-tetra-amine (HY951) at room temperature. 3-aminopropyltriethoxysilane was used as a coupling agent to introduce amine groups on the surface of ZnO and its structure was confirmed by FT-IR. The thermal stability and mechanical properties of in-organic–organic hybrid epoxy nanocomposites having different weight percentages of M-nZnO are investigated by thermogravimetric analysis. Their surface morphology of in-organic–organic hybrid epoxy nanocomposites was analysed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The introduction of M-nZnO improved the mechanical and thermal properties of the in-organic–organic hybrid epoxy nanocomposites. The mechanical characteristics and thermal stability analyses yielded the best results with a 2 wt% addition of M-nZnO nanoparticles. The study's findings clearly suggest that 2 wt% M-nZnO with Af/DGEBA epoxy resin can be used in a wide range of high-performance applications. Interestingly, the Af/DGEBA/M-nZnO epoxy nanocomposites displayed an excellent antibacterial action against high concentrations of Gram-negative bacteria like Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

The hybridization of natural and synthetic fibers is an alternate method to balance the performance and environmental friendliness of fiber metal laminates (FMLs). This research aims to fabricate hybrid aluminum (A)/ carbon fiber (C)/ pineapple leaf fiber (P) reinforced epoxy FMLs with different stacking sequences by the vacuum-assisted resin transfer molding (VARTM) technique. The fabricated hybrid FMLs were subjected to tensile, flexural, thermogravimetric analysis (TGA), and water absorption tests. The tensile and flexural strength of hybrid A1 (ACPCA) surpassed those of non-hybrid AP (APPPA) by 252.77% and 165.08%, respectively. The thermal test shows that the hybrid FMLs A1 with higher CF content leads to better thermal stability than A2 (APCPA). In addition, from the water absorption test, the AP and A2 FMLs, with PALF as outer layers of core materials, absorbed moisture exceeding 6% after 10 weeks, compared to AC (ACCCA) and A1 with CF as outer layers of core materials, which only reached up to 2.88% and 4.22%, respectively. From this study, it is worth pointing out that the hybrid A1 showed comparable performance to non-hybrid AC. Thus, the appropriate hybridization of synthetic and natural fibers can broaden the scope of the practical application of FMLs with improved environmental friendliness in the automotive industry. [ABSTRACT FROM AUTHOR]

Two semi-alicyclic thermoplastic polyimides (PI) have been prepared from stereoisomeric hydrogenated pyromellitic dianhydrides, including 1S,2R,4S,5R-hydrogenated pyromellitic dianhydride (ccHPMDA or H-PMDA) and 1R,2S,4S,5R-hydrogenated pyromellitic dianhydride (ctHPMDA or Hʹʹ-PMDA) and a fluorine-containing diamine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (BDAF), respectively. The derived PI-1 (ccHPMDA-BDAF) and PI-2 (ctHPMDA-BDAF) resins were easily soluble in polar aprotic solvents, such as N-methyl-2-pyrrolidinone (NMP) and N,N-dimethylacetamide (DMAc) and meanwhile they also exhibited good thermoplasticities. Thus, the PI films (thickness: ~25 μm) and sheets (thickness: ~3 mm) were separately prepared from the PI solutions in DMAc and the PI powders, respectively. The stereoisomeric effects in the ccHPMDA-derived PI-1 and the ctHPMDA-derived PI-2 apparently affected the melt-flowability of the polymers. PI-2 exhibited lower melting viscosities than that of the PI-1 counterpart. The PI sheets exhibited obviously reduced optical transparency compared with those of the PI films; however better optical transparency than those of the common thermoplastic PI sheets. For example, PI-2 sheet showed the optical transmittance value at the wavelength of 760 nm (T760) of 69.6%, which was 19.5% lower than that of the analogous PI-2 film (T760 = 89.1%), however 50.3% and 65.7% higher than those of the commercially available PI-ref1 sheet (T760 = 19.3%) derived from 3,3ʹ,4,4ʹ-oxydiphthalic dianhydride (ODPA) and 4,4ʹ-oxydianiline (ODA) and the PI-ref2 sheet (T760 = 3.9%, Aurum® PL450C, Mitsui Chem. Co, Ltd., Japan), respectively. Meanwhile, the PI-1 and PI-2 sheets showed the heat deflection temperatures (HDT) of 261.0 °C and 265.0 °C, respectively, which were obviously higher than those of the referenced PIs. At last, the PI sheets exhibited good mechanical properties, including high flexural strength (130.0 ~ 132.0 MPa), flexural modulus (2.87 ~ 2.96 GPa), compression strength (124.4 ~ 149.3 MPa), compression modulus (1.49 ~ 1.59 GPa), and impact strength (129.0 ~ 139.6 KJ/m2). [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) was synthesized from the graphite powder by modified Hummer's method. Functionalized multi-walled carbon nanotubes (f-MWCNTs) containing –COOH groups were prepared to improve the compatibility of carbon nanotubes with the polymer matrix. Polyethylene terephthalate (PET) hybrid nanocomposites were made by melt blending by micro-compounding. In all compositions, the investigation was done at a constant filler amount of 2 wt%. Fourier transform infrared spectroscopy (FT-IR) and Raman studies revealed that there have been only physical interactions between PET matrix, GO and f-MWCNT fillers. Both water absorption and Shore hardness D increased with increase in GO content or decrease in f-MWCNT till both the nanofillers are equal and decreased upon further increase of GO content or decrease in f-MWCNT. Morphological studies were carried out by FE-SEM and AFM. Tensile and flexural modulus, impact strength, glass transition, melting temperature and thermal conductivity of hybrid nanocomposites were higher than the neat PET. It was also observed that wettability increased with increase in surface roughness. The 3D geometrical bridge between GO (2D) and f-MWCNT (1D) made the hybrid more dispersible and effective for different applications, and a 3D model is proposed. [ABSTRACT FROM AUTHOR]

Composites due to its advantageous properties for different construction purposes and outdoor applications have gained significant popularity in recent years. The utilization and recycling of waste feathers from animal husbandary is a worldwide problem. Bio-composite materials from such fibers have numerous intriguing characteristics, such as biodegradability, low density, and inexpensive production costs, as compared to composite materials reinforced with synthetic fibers. In this study, green composite based on chicken feather fiber as a reinforcing agent, modified epoxidized soybean oil as resin, and rosin derivative as crosslinker was prepared successfully via compression molding technique by maintaining the fiber/resin ratio at 30:70 and the percentage of rosin derivative was varied from 0 to 40 (wt%). The resulting bio-composites were characterized by Fourier transformed infrared (FT-IR) spectroscopy. DFT calculations for the reactants and the probable crosslinking reaction were carried out which was also substantiated by FTIR spectroscopy. Thermogravimetric analysis (TGA) was done to observe the thermal stability of the bio-composites. Scanning Electron Microscopy (SEM) was used to study the morphology of the biocomposites. An enhanced UV resistance was observed for the composites loaded with rosin derivative as supported by lower weight loss, carbonyl index, and SEM analysis. After biodegradation, a significant loss in weight and mechanical values of the samples were observed. However, composite loaded with 30 wt% of rosin derivative revealed highest enhancement in all the properties. This work represents a major step in fabricating lightweight and biodegradable composites for greener environment and has the potential to be employed in various structural applications. [ABSTRACT FROM AUTHOR]

Natural resource-driven approaches to bioengineering plastics are being developed to compete in the automobiles, power, and other sectors. Polytrimethylene terephthalate (PTT) is a particular of them, and it was chosen for the current investigation to build an advanced nanocomposite material. Using a twin-screw micro compounder, injection moulded PTT/Graphene-Oxide (GO)/Carboxyl functionalized Multiwall Carbon nanotube (f-MWCNT) hybrid nanocomposites were prepared. The impact of GO and f-MWCNT reinforcement on the composite's thermal and mechanical characteristics of hybrid nanocomposites was examined. GO was synthesized from the graphite powder by modified Hummer's method and MWCNTs were functionalized using the concentrated sulfuric acid (H2SO4) and nitric acid (HNO3) with a volume ratio of 3:1 in an ultrasonic bath at room temperature. In all formulations, the investigation was done at a constant filler amount of 2 wt%. To understand the chemical interaction between PTT and nanofiller, Raman spectroscopy was used and to examine the state of dispersion, scanning electron microscopy (SEM) was systematically analysed. In comparison to pristine PTT, the water absorption, tensile strength, flexural strength and impact strength of hybrid nanocomposites were improved marginally. It was also observed that GO has more prominent in increasing the mechanical properties of the hybrid and f-MWCNT in thermal properties. The 3-D geometrical bridge between GO (2-D) and f-MWCNT (1-D) made the hybrid more dispersible and effective for different applications. [ABSTRACT FROM AUTHOR]

The kinetics of austenite decay and the modeling of thermal welding cycles on the installation of high-frequency currents of various sections of the thermal influence zone of medium-carbon medium-alloy steels were studied. The change in hardness and toughness at metal heating temperatures of 170°C to 1300°C is presented. The mechanical properties of the simulated thermal influence zone and the real welded joint are compared. [ABSTRACT FROM AUTHOR]

As the 3D printing polymer material extrusion process is moving beyond niche markets and into large-scale manufacturing, still commercial systems employed by this process work in an open-loop environment where no feedback or control solution is provided from batch-to-batch production. This issue causes significant differences in part quality and generates lower production efficiency. However, there are substantial innovations in terms of smart manufacturing (SM) technologies, where the use of integrated smart sensors, the internet-of-things (IoT), big data, and artificial intelligence (AI) tools, that applied can let the systems evolve into a closed-loop higher rentability mass production process. This study investigates the available smart manufacturing technologies applied to evaluate the current state-of-the-art. This paper used scientometric analysis to analyze the most important contributions in this area. A systematic review aims to verify the results and understand the publications related to the polymer material extrusion process in detail. The analysis concludes that the most investigated aspect is the relation between the mechanical properties of materials and the high anisotropy presented in the process. The conclusions show that different sensors have been integrated, such as digital cameras, thermal cameras, thermocouples, and accelerometers, among others. They all obtain metrics and use data models to make supported decisions. Furthermore, AI algorithms have been applied to the process, and significant progress has been made to detect quality failures or part defects. Finally, as a substantial conclusion, it has been found that there is still no system in the market that can provide integral feedback control and process adjustment in real-time. This brings a positive opportunity to improve and achieve a fully smart manufacturing system in the 3D printing polymer material extrusion process. [ABSTRACT FROM AUTHOR]

This present study investigates the role of adding sugarcane bagasse biosilica (SBB) fine particle on Opuntia dillenii fibre (ODF)-reinforced epoxy resin composite and its mechanical, thermal and laminar shear strength properties. In this study, the biosilica particles were prepared from Indiana sugarcane bagasse via thermo-chemical process. The fibre and particles were silane surface-treated (SST) using 3-aminopropyltrimethoxysilane via acid hydrolysis process. Hand layup was used to create the composites, which were then post-cured at 120 °C for 48 h. The composites were characterized using ASTM standards in order to evaluate the mechanical, thermal and laminar shear strength properties. The tensile strength of SST fibre and particle produced the highest strength of 178 MPa for 40 vol.% of fibre and 2 vol.% of particle in epoxy resin. Similarly, the SST fibre and particle retained high thermal stability than as-received fibre and particle in the composite. The laminar shear strength of SST fibre shows the highest value of 33 MPa against shear load. The SEM morphology shows highly adherence surface between SST fibre and resin. Thus, in the process of making biocomposites using plant-based fibres, the silane treatment is mandated in order to achieve high performance. [ABSTRACT FROM AUTHOR]

Ir doping is an effective method used to strengthen and toughen Pt–Rh alloy and improve its high-temperature properties. However, Ir and Pt–Rh alloys are infinite solid solution alloys, and their microstructures are difficult to observe to understand their mechanism of action. Therefore, the stability and mechanical and thermal properties of a series of Pt–20Rh–xIr (x = 0, 5, 10 and 20) alloys were calculated using first-principle studies based on density functional theory. The results show that with an increase in the Ir content, the Young's modulus and hardness of Pt–20Rh–xIr initially decrease and then increase. The largest Young's modulus (436.243 GPa) and hardness (18.453 GPa) were achieved when the Ir content was 20 wt%. Meanwhile, the thermodynamic calculation results show that with an increase in the Ir content, the thermal stability of Pt–20Rh–xIr was significantly improved, and the thermal expansion coefficient of Pt–20Rh–xIr was only 63% of that observed for Pt–20Rh. The above results imply that the addition of 20 wt% Ir gave the best effect on improving the strength, toughness and high temperature properties of Pt–20Rh alloy. This study provides theoretical guidance for further application of Pt–Rh alloy in the aviation field. [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]

In this work, the melt polycondensation method was used to synthesize aliphatic polyesters from 1,12-dodecanediol and aliphatic diacids with even carbon atoms. Gel permeation chromatography, hydrogen-1 nuclear magnetic resonance (1H NMR), infrared spectroscopy, differential scanning calorimetry, wide-angle X-ray diffraction, thermogravimetric analysis, tensile test, dynamic mechanical analysis, and rotational rheometer were used for characterization. All polyesters had high weight average molecular weight (> 60,000 g/mol). Poly(1,12-dodecylene adipate) had the lowest weight average molecular weight (66,360 g/mol) and poor thermal stability. Four polyesters had very flexible molecular chains and shared a crystalline structure with polyethylene. Poly(1,12-dodecylene octanedioate) and poly(1,12-dodecylene sebacate) had tensile strength of 20.8 MPa and 25.3 MPa, respectively, and elongation at break of 255% and 254%, respectively, meaning that their tensile properties were similar to those of polyethylene. [ABSTRACT FROM AUTHOR]

Bio-based interpenetrating polymer networks (IPNs) with tunable thermal and mechanical properties were prepared by bio-based polyurethane (PU) and epoxy resin (EP) derived from plant oils. The cure reaction, dynamic mechanical properties, thermal stability, mechanical performance and morphology of bio-based PU/EP IPNs were characterized by Fourier transform infrared spectroscopy, dynamic mechanical analysis, thermogravimetry, universal test machine and scanning electron microscopy. Dynamic modulus, glass transition temperature, thermal stability and tensile strength of bio-based EP/PU IPNs decreased in the content of soybean oil-based PU prepolymers. However, the damping properties of bio-based EP/PU IPNs increased in the content of soybean oil-based PU prepolymers. The elongation at break of bio-based EP/PU IPNs was greatly higher than that of the plant oil-based EP. The elongation at break of the bio-based EP/PU IPN containing 20% soybean oil-based PU prepolymer was fourfold higher than that of the plant oil-based EP. Soybean oil-based PU prepolymer significantly improved the damping properties and the elongation at break of the plant oil-based EP. By adjusting the mass ratio of the plant oil-based EP to the soybean oil-based PU, the glass transition temperature, damping and mechanical properties of bio-based PU/EP IPNs can be optimized. [ABSTRACT FROM AUTHOR]

Abaca is a strong competitor among natural fibres for use as the reinforcement of polymer composites. Due to its high durability, considerable fibre length, flexibility and mechanical strength, abaca shows good potential as a renewable source of fibres for application in technological and industrial fields. Discussing the influence of various treatment strategies, such as alkali and silane, for the preparation of abaca-based composites results in the improvement of their properties over that of bare polymer materials and that of other synthetic fibres. The enhanced characteristics of abaca fibre reinforced composites are widely explored for a variety of applications in automotive and other industries. These include for example roping and woven fabrics, currency notes, cigarette filter papers, vacuum bags, tea bags, cellulose pulp for paper and packaging, and materials for automotive components, etc. In particular, the effective use of abaca fibre reinforced polymer composite in manufacturing external parts of cars, using therefore also thermoplastic matrices, has become popular. The gaps in research from the literature that show the scarcity of studies on topics such as simulation and designing of mechanical characteristics of abaca fibre composites constructed on polymer matrices, such as epoxy, polylactide, high density polyethylene, phenol formaldehyde and polyester are also highlighted. The results indicate that abaca is particularly flexible to be used in different sectors, in combination with various matrices, and in hybrid composites with various fibres. Further work would necessarily involve the larger consideration of abaca textiles with different areal weights in the production of composites, and a widespread introduction of abaca in datasets for the automated selection of natural fibres for composites reinforcement. [ABSTRACT FROM AUTHOR]

One of the approaches to improve the properties of polymers is to use additives in them. In the last few years, nanoscale additives have received attention due to the favorable properties they give to polymers in low concentrations. POSS or polyhedral oligomeric silsesquioxane has unique properties due to its nanometer size and organic–inorganic nature. The rigid structure of POSS and its compatibility with all types of polymers make their use attractive in various polymer industries. The concentration, structure of the mineral core, and type of POSS organic groups can affect the final properties of polymers containing these nanostructures. Chemical mixing of POSS with polymer increases the viscosity of the system, while physical mixing decreases the viscosity of the polymer. These nanostructures can improve properties such as tensile strength, modulus, and toughness of the polymer. Polymers with low concentrations of POSS have the advantage of high thermal stability and low flammability, which makes them ideal for applications in the aerospace industry where materials must withstand extreme temperatures and harsh environments. In addition, the low dielectric constant of POSS-containing polymers makes them useful for use in electronic components. The high specific surface of POSS allows the use of these nanostructures as supports for various catalysts. POSS is used in a wide range of industries including aerospace, biomedical, electronics and chromatography columns, etc. [ABSTRACT FROM AUTHOR]

In the recent years, additive manufacturing (AM) has been widely expanded for manufacturing the polymer and polymer-based composite parts. The main drawback of the material extrusion additive manufactured parts is the weaker mechanical properties in comparison to the manufactured parts by the conventional methods. The stated weak mechanical properties are due to the weak adhesion between the deposited layers. The poor adhesion between the deposited layers in material extrusion additive manufacturing process is due to the fact that the previous deposited filament (n-1) is already cooled and solidified. To ensure the appropriate adhesion between the two adjacent filaments, the temperature of the first deposited layer (n-1) has to be high enough to obtain a suitable adhesion to the subsequent layer (n) but in an optimum range to avoid the lack of the dimensional accuracy. Therefore, a precise and local measurement of the temperature on the scale of the diameter of the filaments is necessary. In this study, four important process parameters (liquefier temperature, layer height, print speed, and bed platform temperature) were selected to study their effects on the rheological behavior and temperature evolution of the PA6 and CF-PA6 materials during material extrusion process. Then, the impact of the short/chopped reinforcement on the thermal and mechanical properties of the material extrusion additive manufacturing processed polymer-based composites were studied by comparing the obtained results from PA6 and CF-PA6 parts. In one experiment, it was observed that increasing the liquefier temperature from 220 to 240 °C increased the tensile strength and crystallinity percentage of the manufactured PA6 and CF-PA6 specimens. It was determined that the crystallinity percentages of PA6 and CF-PA6 specimens increased from 12.51 to 14.40% and from 19.97 to 20.51%, respectively. One of the existence effects of carbon fibers is highlighted in the higher crystallinity values of the CF-PA6 specimens comparing PA6 specimens. Finally, a time–temperature-transformation diagram was plotted to determine the processability condition of the utilized materials. It can be helpful for the designers and researchers to find out the optimal material extrusion additive manufacturing process parameters condition for the utilized raw materials. [ABSTRACT FROM AUTHOR]

In this work, the effect of uniaxial stretching on the crystallization and melting behaviors, miscibility, crystal structure, and mechanical properties of neat poly(L-lactide) (PLLA) and miscible PLLA/poly(vinyl acetate) (PVAc) blends was investigated. Stretching process could generate remarkable influence on thermal properties of neat PLLA and PLLA/PVAc blend. With stretching ratio increasing, macromolecular chains orientation and crystallization were promoted, resulting in a decrease in cold crystallization temperature and an increase in glass transition temperature, and a significant increase in crystallinity. In addition, after stretching process PVAc still inhibited the crystallization of PLLA. PLLA/PVAc blends were completely miscible blend system which had only one glass transition temperature before and after stretching process, and phase separation did not occur after stretching process. When stretch ratio increased, amorphous PVAc had greater influence on the tanδ transition peak and storage modulus increased markedly, which was benefit to the improvement of heat resistance. The α′ crystal form was produced in blends after stretching process. Stretching process with moderate stretch ratio can be utilized to improve the mechanical properties of PLLA with simultaneous enhancement of tensile strength, fracture strain and stiffness. The findings in this work provide an insightful understanding of the effect of stretching process on miscible PLLA blend and the improvement of toughness, which will facilitate the large-scale practical application of PLLA. [ABSTRACT FROM AUTHOR]

Recently, the applications in the automotive and packaging sectors have been developed for rubber-toughened Polypropylene (PP) nanocomposites with desired thermal and mechanical properties. In this work, PP/Nitrile butadiene rubber (PP/NBR) blends and nanocomposites containing graphene oxide (GO) and chemically functionalized GO with γ-glycidoxy propyl trimethoxy silane (GPTMS) and aminopropyl triethoxy silane (APTS) were prepared and studied via melt blending process using Brabender mixer. In addition, the effect of three compatibilizer components (PP-g-MAH, PP-g-NH2, and PP-g-OH) on the properties of the systems was also investigated. The intercalation of polymer chains into GO and functionalized GO layers was confirmed by XRD analysis. According to the TGA findings, the addition of GO-APTS, GO-GPTMS, and compatibilizers significantly improved the thermal stability. The incorporation of graphene materials increased the PP/NBR melting and crystallization temperatures, as well as the degree of crystallinity, according to DSC analyses. Moreover, from the mechanical evaluation, PP/NBR/PP-g-NH2/GPTMS-GO exhibited superior Elongation at break and impact resistance compared to the other compatibilized nanocomposites. [ABSTRACT FROM AUTHOR]

First-principles calculations based on density functional theory have been used to explore the structural, mechanical, vibrational and thermal properties of Nodal-Line Semimetal CaAgX (X = P, As) for the first time in detail. Firstly, lattice parameters are obtained, and it is found that they are in excellent agreement with previous experimental data. The calculated elastic constants for hexagonal structures satisfy mechanical stability conditions. Thus, using elastic constants, bulk modulus, B/G ratio, shear ratio, Poisson's ratio, Debye temperature and minimum thermal conductivity have been calculated. An attentive investigation of elastic and mechanical properties reveals that these compounds are brittle, and the hardest one is CaAgP, which also has the highest thermal conductivity. Also, the ionic character is dominant in the bonding mechanism for all the studied materials. These materials are also dynamically stable because negative frequencies have not been observed. Lastly, CaAgP reaches the Dulong–Petit limit (≅75 J mol–1 K) slower than CaAgAs, which agrees with previous experimental study results. [ABSTRACT FROM AUTHOR]

PLA and its nanocomposite containing 3% chitosan nanoparticles (PLA-3CsNP) were studied to see how γ -irradiation affected their characteristics. Different doses of γ -irradiation were applied to the investigated materials under inquiry (5–40 kGy) using 60Co at ambient conditions. The irradiation materials were characterized by FT-IR, GPC, mechanical tensile test, DSC, XRD, and TGA in solid and chloroform solutions. The molecular weight of the studied materials was lowered when the irradiation dose was increased, indicating that γ-irradiation had the dominating effect through oxidative degradation, and chain scission. The addition of chitosan to PLA reduces the impact of γ-irradiation, while the samples irradiated in solution showed more degradation after irradiation than irradiated solid films. Irradiation caused a decrease in tensile strength and elongation at break values. Both the melting temperature (Tm) and the glass transition temperature (Tg) decreased as the irradiation dose was increased. The crystallization peak temperatures were reduced when pure PLA was irradiated in solution. The thermal stability of PLA was diminished as the irradiation dose was raised, and this effect was more pronounced in samples irradiated in chloroform solution. [ABSTRACT FROM AUTHOR]

In order to obtain thermoplastic polyurethane elastomers (TPUEs) with good thermal and mechanical properties, in this work, poly(ether carbonate) polyurethane elastomers (PECUEs) with mixed soft segments are synthesized using a non-toxic, non-polluting and simple process of melt polycondensation. Thermal and tensile tests show that PECUEs are elastomers with excellent low-temperature elasticity and mechanical properties (e.g., Tg of − 36 °C, Td,5% of 284 °C, tensile strength of 36.1 Mpa, elongation at break of 1308% and resilience at 200% fixed length of 90%). This work is the first to synthesize PECUEs by melt polycondensation process. The products have good performance, green process and great potential for industrial applications. [ABSTRACT FROM AUTHOR]

In this study, PDMS incorporated with SWCNTs have been fabricated via solution casting method for industrial applications and characterized by the analyses of SEM, FTIR, TGA, AFM, and MST. The modified membranes were further analyzed for CO2, O2, and N2 gas permeability. The strategic membranes have five different weight ratios (0.013, 0.025, 0.038, 0.050, 0.063) compared to neat PDMS membranes. The even distribution of SWCNTs in PDMS provided results that showed improvement in thermal stability. However, mechanical strength has been weakened with increased concentration of nanofiller because of the increase in the number of SWCNTs by increases that imperfections become more severe. The designed polymeric membranes with good thermal stability and adequate mechanical strength can be used for the selectivity and permeability of CO2, O2, and N2 gases. The effect of the PDMS-SWCNTs on gas permeability has been studied. 0.063 wt.% SWCNTs presented the maximum permeability of CO2 gas while maximum O2 and N2 gas permeability have been obtained by 0.013 wt.% SWCNTs. The ideal selectivity of mixed (50:50) gas conditions has been tested. The maximum CO2/N2 ideal selectivity was obtained by 0.050 and 0.063 wt.% SWCNTs while maximum O2/N2 ideal selectivity obtained by 0.050 wt.% SWCNTs. Therefore, the fabrication of this novel SWCNTs-PDMS membrane may lead to separating the industrial exhaust and be used as a potential membrane for environmental remediation in the future. [ABSTRACT FROM AUTHOR]

In the present work, the fused filament fabrication method was applied to fabricate polypropylene nanocomposite sheets reinforced with TiO2 nanoparticles. The friction stir welding was also applied to join the polypropylene/TiO2 nanocomposite sheets. The response surface methodology was used to examine the effect of the parameters of rotational speed, welding speed, and TiO2 content on the mechanical properties of the obtained welds. The mechanical properties of weld samples were examined by tensile and hardness tests, while their thermal properties were studied by thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. The results revealed that the addition of TiO2 nanoparticles increased the melting point and crystallinity percentage of the polypropylene nanocomposite up to 170.2 °C and 57.7%, respectively, due to good interfacial interaction between TiO2 nanoparticles and PP matrix. The weld strength enhanced (about 21%) when rotational speed increased from 500 to 1000 rpm, while the hardness deteriorated (about 20.5%). The increase of welding speed from 20 to 40 mm/min resulted in an improvement of hardness by 13.5% and a decline of tensile strength by 9%. The highest hardness of the weld joint (12.5 HV) was obtained at 4 wt% TiO2, whereas the tensile strength of the weld joint maximized (43 MPa) at 2 wt% TiO2. Finally, the concurrent enhancement of hardness and tensile strength was achieved by a rotational speed of 833 rpm, welding speed of 20 mm/min, and TiO2 content of 3.5 wt%. At the optimal conditions, the tensile strength and hardness improved up to 43.87 MPa and 12.45 HV, respectively. [ABSTRACT FROM AUTHOR]

The aim of the study was to study the effect of cheap bio-based monomer 2,5-thiophenedicarboxylic acid on poly(butylene furandicarboxylate). Bio-based copolyesters were successfully synthesized by two-step melt polycondensation using 2,5-thiophenedicarboxylic acid (TDCA), 2,5-furandicarboxylic acid (FDCA) and 1,4-butanediol (BDO). Compared with FDCA, the price of TDCA is lower. The main purpose of this study is to add different amounts of TDCA to reduce the cost of polyester and to investigate the effect of TDCA on the properties of poly(butylene furandicarboxylate) (PBF). It can be determined that the expected copolymers were indeed synthesized by FTIR and 1H NMR spectra. DSC and WAXD results suggested that PBFTF27, PBFTF51 and PBFTF77 show isodimorphism behaviors. Because the angle between two carboxyl groups in TDCA is larger than that of FDCA, and the electronegativity of sulfur atom is weaker than that of oxygen atom, the glass transition temperature decreases due to the increase in the flexibility of the chain with the increase in TDCA. Compared with PBF, the toughness of poly(butylene 2,5-thiophenedicarboxylate) (PBTF) and copolyesters increased significantly. Poly(butylene furandicarboxylate-co-butylene 2,5-thiophenedicarboxylate) can be used in the packaging applications. [ABSTRACT FROM AUTHOR]

In this study, poly (vinyl acetate) (PVAc) containing boehmite nanoparticles were synthesized by an emulsion polymerization strategy. The prepared nanocomposites were analyzed by FT-IR, UV–visible, XRD, optical microscopy, AFM, FE-SEM, HR-TEM, DSC and TGA. Tensile testing techniques and impedance spectroscopy were used to investigate the impact of nanoparticles on the mechanical and electrical properties of PVAc. The characteristic peak of boehmite in the polymer was identified by FT-IR spectra. The optical bandgap energy decreases while the refractive index increases sharply with the addition of boehmite up to 7 wt% loadings. The semicrystalline structure of the composite system was revealed by the XRD pattern. The addition of boehmite to PVAc increases the surface roughness measured by AFM. The FE-SEM and optical microscopy confirmed the presence of uniformly distributed nanoparticles in the polymer. The results from HR-TEM confirm the structural variation of PVAc with the nano-size distribution of boehmite. DSC results revealed that increasing the nanoparticle content increased the glass transition temperature of the polymer nanocomposites. TGA results revealed that the presence of boehmite in the polymer matrix significantly improved the thermal stability of PVAc. The findings of the mechanical test indicate that the tensile strength and Young's modulus of polymer composites was improved by increasing the concentration of nanoparticles. The electrical property data reveal that increasing the frequency decreased the dielectric constant while increased the AC electrical conductivity. Overall, the results showed that the prepared nanocomposite with high tensile strength, conductivity, and dielectric constant can be used to fabricate optoelectronic devices and EMI shielding. [ABSTRACT FROM AUTHOR]

A review of the mechanical property development of concrete containing calcined clay was performed. A comparison of compressive and tensile strength results showed that concrete can be made to have equivalent or higher strength as an ordinary portland cement (OPC) system with up to 30% calcined clay or 50% blend of calcined clay and limestone fines in a limestone calcined clay cement (LC3) system, as long as the kaolinite content in the clay used is above 40%. Most of the strength development in these systems occurs during the first 7 days, making extended wet curing not necessary in these systems. Calcined clay systems are subject to the cross-over effect because of the high solubility of ettringite and lower cement degree of hydration at elevated temperatures. Concrete creep and shrinkage were found to be a function of the clay kaolinite content and replacement level. Bond strength was improved by the use of up to 20% metakaolin. [ABSTRACT FROM AUTHOR]

Foam concrete possesses low density and excellent thermal insulation properties and has been widely used in construction industry. Considering the recycling and reusing of coal gasification slag (CGS), a solid waste product in the coal chemical industry, CGS was used as the supplementary cementations material to prepare foam concrete (CGS-FC) in this work. The influence of the CGS content and water-binder ratio on the pore structure, mechanical and thermal properties was investigated. The results show that the CGS content and water-binder ratio directly impact the fluidity of the slurry, which affects the internal pore structure of the specimens after molding. And a CGS-FC with a compressive strength of 6.89 MPa, thermal conductivity of 0.24 W/m K, and a bulk density of 867 kg/m3 was successfully produced when the CGS content was 30% and water-binder ratio was 0.5. In particular, the utilization of CGS to prepare foam concrete product has recycling efficiency and environmental benefit. [ABSTRACT FROM AUTHOR]

In order to further improve the thermal conductivity and mechanical properties simultaneously of the base alloy (Al-7Si-0.6Fe-0.5Zn alloy) treated by B/La/Sr modification, the La content was further optimized in the B/La/Sr-modified process, and the Ce element was added into the melt treated by B/La/Sr modification to get higher improvement. For the B/La/Sr-modified alloys, when the content of La decreases from 0.15 to 0.05%, the thermal conductivity (λ) and integrated mechanical properties index (Q) increase 3.1W/(m·K) and 21.1MPa, respectively. In the B/La/Ce/Sr-modified alloys, the λ and Q increase simultaneously with the increase of the Ce content, reaching the maximum of 179.2W/(m·K) and 380.2MPa, respectively, when the Ce content reaches 0.5%, and then decrease simultaneously with the further increase of the Ce content. When the Ce content is not more than 0.5%, the morphology change of the Fe-rich phases is the main reason for the simultaneous improvement of the thermal conductivity and the mechanical properties of the B/La/Ce/Sr-modified alloys. When the Ce content is more than 0.5%, the precipitation of the needle flake-like Ce-rich phases and coarse flake-like Si phases is the main reason for the simultaneous deterioration of the mechanical properties and thermal conductivity. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising alternative to petroleum-based polymers, however its high brittleness limits its practical applicability. In this study, two polyurethane elastomers (PUa and PUb) containing poly (ε-caprolactone) or poly(ε-caprolactone)/poly(butylene adipate) as soft segment and different hard segments content (38.16% for PUa and 53.12% for PUb) were synthesized and melt blended with PHBV in various proportions. The addition of 5–15 wt% PU elastomers to PHBV did not significantly change its thermal stability; however, the presence of PUs decreased the crystallization temperature of PHBV by up to 9 °C, and the crystallinity of PHBV decreased from 48.2% to 42.2 or 43.6% in the blends with 15% PUa or PUb, indicating the development of some interactions between PHBV and PUa/PUb. The addition of PUa to PHBV increased its elongation at break by up to 70%, a weaker effect being observed with PUb. Remarkably, a slight variation in the tensile strength and modulus, which remained close to those of neat PHBV, was concomitant with the increased ductility. The fatigue resistance of the selected blends was estimated by a DMA cyclic test under controlled force from − 20 to 70 °C, this test clearly differentiating the blends. [ABSTRACT FROM AUTHOR]

Fibers obtained from curauá, a species of small ornamental pineapples, are known for their good mechanical properties and benefits, such as ballistic resistance, in composites. To obtain a quantity of curauá suitable for commercial application, in vitro cultivation of the plant is tested. In this work, we produced curauá plants via tissue culture (micropropagation technique) and extracted the fibers. The fibers grown in vitro were characterized to determine moisture, ash, extracts, lignin, hemicelluloses, holocellulose, and cellulose contents; and infrared spectroscopy (FTIR–ATR), X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and mechanical testing and analysis were performed. Compared with data on curauá fibers grown traditionally––i.e., cultivated outside of a laboratory setting––this curauá fiber presented a higher content of cellulose (77.2%) and lower hemicellulose content (6.8%). Another unique feature was the high crystallinity of the cellulose present in the fiber (73.53%), which reflected good thermal and mechanical properties. This study indicates that the micropropagation technique is highly advantageous for higher-scale production of this fiber for application in composites, as it generates high-quality fibers grown in a controlled plant growth environment. [ABSTRACT FROM AUTHOR]

Silica nanoparticles were reported that can improve the fire safety and mechanical properties of polymers simultaneously due to excellent rigidity and physical barrier effect. However, its efficiency was limited by the agglomeration in polymers due to their high specific surface energy. Silica@ polydopamine (SiO2@PDA) was prepared by a facile self-polymerization method to comprehensively improve fire safety, thermal stability, and mechanical properties of plant fiber-reinforced polymer (PFRP) composites. The results of micro-morphology confirmed that the SiO2@PDA nanoparticles exhibit better dispersion state in epoxy matrix. The introduction of SiO2@PDA further increased the thermal decomposition temperature and the yield of graphitized char residue of PFRP composites compared to pure silica nanoparticles. And the fire safety of composites including limiting oxygen index, heat parameters, smoke parameters and mass loss rate was improved effectively. Particularly, the time to ignition of composites was delayed by 30 s, which was beneficial for individuality escape and rescue. Meanwhile, the improvement of storage modulus suggested the SiO2@PDA enhanced the mechanical properties of the PFRP composites. And it was proved that PDA can improve the graphitization degree of char layer and release inert gas including NH3 and CO2 during combustion. The effectiveness of non-toxic PDA in enhancing the quality of char layer and optimizing the interface to improve the dispersion state of nanoparticles appeared promising potential in the field of manufacturing fire-safe polymer-matrix composites. [ABSTRACT FROM AUTHOR]

The molecular dynamics simulations based study of graphene (Gr) reinforced polymer nanocomposite (PNC) is a very intense research field due to the enormous range of possible applications involving such materials. Current review focuses on the reinforcing mechanisms behind the enhancement of the mechanical, thermal, and tribological properties of Gr-based PNC based on molecular dynamics (MD) simulations. It also reviews the capabilities of MD simulations to reproduce the experimentally measured materials properties and behaviour of Gr-based PNC. This review-based investigation summarizes the current literature of the MD simulation studies as well as comparisons for the tribo-thermo-mechanical properties of Gr-based PNC and identification of the suitable simulation protocols for model development, characterization, and mechanism analysis. The careful review of published MD simulation-based articles indicates that two important factors help to reproduce the experimentally measured materials properties and behaviour of Gr-based PNC. They are mainly (a) simulation models (material used for reinforcement, e.g. Gr and Gr derivatives) development and (b) simulation run parameters. In this review, details about those factors have been discussed keeping major consideration of Gr effect (e.g. shape or length, orientation, clustering, weight fraction, different layer, functionalization, and defective condition). Finally potential applications, current challenges and future prospects are discussed which can be useful to the research community. [ABSTRACT FROM AUTHOR]

The possible structures of technetium diboride under ambient conditions are predicted by the structure prediction algorithm CALYPSO with density functional theory calculations, and their phase stability, mechanical properties and thermal conductivity are further investigated. The results showed that P63/mmc (hP6-TcB2), P6/mmm (hP3-TcB2), Pmmn (oP6-TcB2), R 3 ¯ m (hR9-TcB2), Cmcm (oC12-TcB2) are all mechanically and dynamically stable. Moreover, the Vickers hardness of the five structures is evaluated by empirical model. In which, hP6-TcB2 has the highest hardness (38.4 GPa), and hP6-TcB2, oP6-TcB2, and hR9-TcB2 are both the potential hard materials. In addition, the elastic-dependent anisotropy properties of these structures are further characterized by three-dimensional graphical representations. The anisotropic order of bulk modulus B is hR9 > hP6 > oP6 > hP3 > oC12, while the anisotropy ranking of Young's modulus E and shear modulus G should be hP3 > oP6 > hP6 > hR9 > oC12. Finally, the minimum thermal conductivity of TcB2 in different structures are further investigated by using Clarke's and Cahill's models. The results showed that these technetium diborides may also be potential high-temperature thermal barrier coating materials. [ABSTRACT FROM AUTHOR]

In this study, a multifunction polymeric adhesion promoter and anti-aging compound based on the triethanolamine salt of acrylamide acrylic acid copolymer (COS) was prepared and characterized using Fourier-transform infrared spectroscopy (FTIR). The impact of different COS contents on the tensile, adhesion, and thermal properties of NBR composite and NBR/PET sandwich was evaluated. The NBR composites containing COS displayed good retention of their mechanical properties with increasing thermal ageing time, while the composite without COS showed a decrease in its mechanical properties. The highest tensile strength (17.5 MPa with a retention value of 0.6%) after 7 days of thermal aging was recorded for NBR composite, which contains 5 phr (parts per hundred parts of rubber) of COS (COS 5), compared to NBR composite without COS (COS 0), which recorded 15.1 MPa with a retention value of -27.4%. In addition, the COS 5 composite displayed an improvement in peel strength of 16.4% compared to the COS 0. The results of the thermogarvemetric analysis (TGA) supported the anti-thermal ageing effect of COS, where the initial decomposition temperature (Ti) value increased by 11.7 and 9.3 °C, after addition of 5 and 10 phr of COS to NBR composite, respectively. In addition, the other thermogravemetric parameters investigated displayed a significant increase in their values, which confirms the improvement in thermal stability of NBR composite in the presence of COS. Also, the air permeability of the PET/NBR sandwich decreased by 80% after the addition of 7.5 phr of COS. [ABSTRACT FROM AUTHOR]

Micro Fibrillated Cellulose (MFC) has gained interest both in academia and industry, but some critical issues must be overcome to exploit the industrial MFC/biocomposites uses. In particular, the first drawback is related to the MFC agglomeration during the primary processing. Encouraging results have been obtained using plasticizers, as dispersing aids, during the extrusion that optimizes the process parameters based on the variation of the melt viscosity. However, even if the plasticizer addition counterbalances the excessive biocomposite stiffness, caused by the addition of the MFC, its eventual migration from the finished product needs to be evaluated to avoid toughness reductions as well as environmental and health issues. In this work, the MFC role in controlling the plasticizer migration was evaluated by analytical modeling based on Fick's second law. The diffusion coefficient, D, over time was evaluated and correlated with the change in mechanical and thermal properties of cast extruded biocomposites. Mechanical and thermal data, analyzed over a 50-day time span, confirmed the expected benefits. The results obtained proved how the approach adopted in this study can be a valuable industrial manufacturing approach. [ABSTRACT FROM AUTHOR]

Blending is an economical and feasible method to improve the properties of polymers. To improve the mechanical properties of ethylene acrylate rubber (AEM), a series of hydrogenated nitrile butadiene rubber (HNBR)/AEM blends were prepared. The mechanical, thermal properties and compatibility of HNBR/AEM blends were investigated in detail. Carbon black filled HNBR/AEM blends exhibited excellent mechanical properties as well as good resistance to high and low temperature. The reactivity of HNBR was higher than that of AEM at a high temperature (180 °C) in air. The crosslinking reaction was more likely to occur in HNBR rubber, while it is not easy to remove small molecules at high temperature. The degradation temperature (Td5%) of AEM (350 °C) was lower than that of HNBR (390 °C), while the hot-air ageing tests indicate that the retention of tensile strength of AEM (95%) was much higher than that of HNBR (58%). HNBR/AEM blends were compatible within the full range of formulations, and have been mutually validated by SEM, dynamic mechanical analysis and mechanical property models of HNBR/AEM blends. [ABSTRACT FROM AUTHOR]