Mori-Tanaka-based statistical methodology to compute the effective Young modulus of polymer matrix nano-composites considering the experimental quantification of nanotubes dispersion and alignment degree

This paper presents a Mori-Tanaka-based statistical methodology to predict the effective Young modulus of carbon nanotubes (CNTs)-reinforced composites considering three variables: weight content, reinforcement dispersion and orientation. Last two variables are quantified by two parameters, namely, free-path distance between nano-reinforcements and orientation angle regarding the loading direction. To validate the present methodology, samples of multi-walled CNTs (MWCNTs)-reinforced polyvinyl alcohol (PVA)-matrix composite were manufactured by mixing solution. The MWCNT/PVA Young modulus was measured by nano-indentation, while the MWCNTs Young modulus was quantified by micro-Raman spectroscopy. Both stretched and unstretched composite specimens were fabricated. Transmission electron microscopy (TEM) and in-plane image analysis were used to obtain fitting coefficients of log-normal frequency distribution functions for the free-path distance and orientation angle. It was evidenced that numerical results fit well to measured values of effective Young modulus of MWCNTs and MWCNT/PVA, with exception of some particular cases where significant differences were found. Microstructural heterogeneities, cluster formation, polymer chains alignment, errors associated with the dispersion, orientation and mechanical characterization procedures, as well as idealization and statistical errors, were identified as possible causes of these differences. Finally, using the proposed methodology and the dispersion and orientation distribution functions experimentally obtained, the effective Young modulus is estimated for three kinds of thermoplastic matrices (polyvinyl alcohol, polyethylene ketone, and ultra-high molecular weight polyethylene) with different kinds of nanotubes (single wall, double wall, and multi-walled), at different weight contents, finding the superior mechanical performance for double-walled CNTs-reinforced composites and the lower one for multi-walled CNTs-reinforced ones.

In-Vivo Neuropharmacological and Anti-Nutrient Study of Methanolic Extract of Lemna Minor

Medicinal plants constitute an important natural wealth of a country. They play a significant role in providing primary health care services to rural people. They serve as therapeutic agents as well as important raw materials for the manufacture of traditional and modern medicine. Lemna minor, the common duckweed is an aquatic freshwater aquatic plant of the genus Lemna. They belong to the family of Lemnaceae, which is monophyletic to the Araceae family. The study assesses In-vivo Neuropharmacological and Anti Nutrient Study of methanolic extract of Lemna minor. The plants were collected from Chandpur were extracted in methanol solvents using soxhlet apparatus. Chemical tests to identify different anti nutrients, total phenolic and flavonids were carried out using specific reagents. Several test such as open field test, hole cross test, hole board test and phenobarbital induced sleeping time test are performed to check possible neurological activity.The study of anti-nutrient properties showed a very high amount of tannin (5.625gm/kg) but a low amount of phytic acid (0.03gm/kg) & alkaloids (0.526gm/kg) comparison with standard value. Total phenolic (19.22 GAE/g dry weight) and flavonoids (7.68 QE/g dry weight) content determine that Lemna minor have a very good amount of phenolic and flavanoids content and which may act as good anti-oxidant. In the study of in-vivo neurological activity the efficacy of Lemna minorextract was compared with standard anxiolytic drug diazepam (1 mg/kg b.w.) showed limited sedation as well as anxiolytic properties in mice. The present study of in-vivo & anti-nutrient is biological evaluation of this plant forms a primary platform for further phytochemical, anti-nutrient & pharmacological studies.

Multiblock Elastomers TPEAA and TPEEA: Physical Structure and Properties

A three series of terpolymers composed of the blocks PTMO (MPTMO = 1000 g/mol) or DLAol (MDLAol = 540 g/mol), PA12 (MPA12 = 2000 g/mol) and xGT (DPxGT = 2) with various chemical compositions of ester block were obtained. The series differ in the chemical structure of the flexible block and weight content of the soft phase. The effect of the number of carbons dividing the terephthalate groups on the synthesis, structure and properties of these elastomers has been investigated. To confirm assumed chemical structure Carbon-13 (13C NMR) and Proton (1H NMR) Nuclear Magnetic Resonance and Fourier-transform Infrared Spectroscopy (FT-IR) were used. The influence of chemical compositions of ester block on the thermal properties and the phase separation of obtained systems were defined by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Thermal Analysis (DMTA) and Wide Angle X-ray Scattering (WAXS). The mechanical and elastic properties were evaluated.

Characteristics of Thermal Parameters and Some Physical Properties of Mineral Eutectic Type: Petalite–Alkali Feldspars

The aim of the research was to check whether the system of three fluxes based on lithium aluminium silicate and alkali feldspars has a eutectic point, i.e., with the lowest melting temperature. Lithium was introduced into the mixtures in the form of petalite, which occurs naturally in nature (Bikita Zimbabwe deposit). Using naturally occurring raw materials such as petalite, sodium feldspar, and potassium feldspar, an attempt was made to obtain eutectics with the lowest melting point to facilitate thermal processing of the mineral materials. In addition, the high-temperature viscosity of the mineral alloys and physical parameters such as density, linear shrinkage, and open porosity were studied. The study showed that in these systems, there is one three-component eutectic at 1345 °C, with the lowest viscosity of 1·105 Pas and the highest density of 2.34g/cm3, with a weight content of petalite 20%, sodium feldspar 20%, and potassium feldspar 20%.

Kinetics of the Thermal Degradation of Poly(lactic acid) and Polyamide Bioblends

Poly(lactic acid) (PLA) and biosourced polyamide (PA) bioblends, with a variable PA weight content of 10–50%, were prepared by melt blending in order to overcome the high brittleness of PLA. During processing, the properties of the melt were stabilized and enhanced by the addition of a styrene-acrylic multi-functional-epoxide oligomeric reactive agent (SAmfE). The general analytical equation (GAE) was used to evaluate the kinetic parameters of the thermal degradation of PLA within bioblends. Various empirical and theoretical solid-state mechanisms were tested to find the best kinetic model. In order to study the effect of PA on the PLA matrix, only the first stage of the thermal degradation was taken into consideration in the kinetic analysis (α < 0.4). On the other hand, standardized conversion functions were evaluated. Given that it is not easy to visualize the best accordance between experimental and theoretical values of standardized conversion functions, an index, based on the integral mean error, was evaluated to quantitatively support our findings relative to the best reaction mechanism. It was demonstrated that the most probable mechanism for the thermal degradation of PLA is the random scission of macromolecular chains. Moreover, y(α) master plots, which are independent of activation energy values, were used to confirm that the selected reaction mechanism was the most adequate. Activation energy values were calculated as a function of PA content. Moreover, the onset thermal stability of PLA was also determined.

Influence of the Cellulose and Soft Wood Fibres on the Impact and Tensile Properties in Polypropylene Bio Composites

Investigation presents an experimental study of mechanical properties of hybrid bio-composites made from man-made cellulose fibres and soft wood microfiller embedded into polypropylene homopolymer matrix at different weight contents. Mechanical properties such as elastic modulus, tensile strength, and impact resistance of the reinforced composites determined for various total weight contents of both biobased fillers were used as the design parameters. The problem was solved by planning the experiments and response surfaces method. The results demonstrate that using the both filler types enhance the mechanical properties. The tensile modulus increases by ~115%. The bio-composite with the highest weight content of man-made cellulose fibres and the lowest content of soft wood microfibers possesses maximum tensile strength (more 66 MPa). Addition of man-made cellulose fibres demonstrate a significant influence on the impact resistance of the investigated composites.

Effect of particle size, shape, and weight percentage of hydroxyapatite (HA) on rheological behaviour of polycaprolactone/hydroxyapatite (PCL/HA) composites

The aim of this study is to investigate the influence of hydroxyapatite’s (HA) particle size, shape, and variation of HA weight percentage on the rheological behaviour of polycaprolactone/hydroxyapatite (PCL/HA) composite. The composite was produced by melt blending process using a single screw extruder assisted with an ultrasonic wave with varied HA weight content (0 wt.%, 10 wt.%, 20 wt.%, 30 wt.% and 40 wt.%). Two types of HA were used, which are needle shape (HAN) and irregular shape (HAS). The rheological behaviour of the PCL/HA composite was investigated through the melt flow index (MFI) test at a varied temperature of 100, 110, and 120 °C. The result indicated that an increase of HA content decreases the MFI values of the PCL/HA composite. At similar content of HA, PCL/HAN composite has higher activation energy with lower MFI values compared to PCL/HAS composite. In conclusion, this study concluded that the particle size, shape, and weight percentage of HA significantly affect the rheological behaviour of PCL/HA composites.

On the Multi-Functional Behavior of Graphene-Based Nano-Reinforced Polymers

The objective of the present study is the assessment of the impact performance and the concluded thermal conductivity of epoxy resin reinforced by layered Graphene Nano-Platelets (GNPs). The two types of used GNPs have different average thicknesses, <4 nm for Type 1 and 9–12 nm for Type 2. Graphene-based polymers containing different GNP loading contents (0.5, 1, 5, 10, 15 wt.%) were developed by using the three-roll mill technique. Thermo-mechanical (Tg), impact tests and thermal conductivity measurements were performed to evaluate the effect of GNPs content and type on the final properties of nano-reinforced polymers. According to the results, thinner GNPs were proven to be more promising in all studied properties when compared to thicker GNPs of the same weight content. More specifically, the glass transition temperature of nano-reinforced polymers remained almost unaffected by the GNPs inclusion. Regarding the impact tests, it was found that the impact resistance of the doped materials increased up to 50% when 0.5 wt.% Type 1 GNPs were incorporated within the polymer. Finally, the thermal conductivity of doped polymers with 15 wt.% GNPs showed a 130% enhancement over the reference material.

Mechanical Characterization and Fracture Analysis of Epoxy Resin Composites Reinforced with Quasi-Unidirectional Salago Fibers

The good environmental effect and possible cost reduction which can be achieved by reinforcing natural fibers in composites while improving some properties led to the development of these materials in various fields. In terms of mechanical properties of composites with natural fibers, both fiber loading and their orientation in the matrices are important factors. In this research work, the effects on the mechanical properties of reinforcing quasi-unidirectional salago fiber in epoxy resin were investigated. Varying alkaline treated fiber contents of 5 %, 10 % and 15 % by weight were characterized through tensile, flexural and impact tests. Fracture analysis after mechanical testing was done with the aid of optical microscopy. As the fiber weight content increases, results revealed enhancements on tensile strength, modulus of elasticity, flexural modulus and impact strength. Overall, the 15 wt. % fiber loading obtained the highest mechanical properties with average tensile and Izod impact strengths of 89.2 MPa and 137 J/m, respectively.

Ultrasonic Preparation of PN For The Photodegradation of 17ß-Estradiol In Water And Biotoxicity Assessment Of E2 After Degradation

This study prepared a novel Phosphorene (PN) and load it onto TiO2 to fabricated PN-TiO2, to effectively photo degrade the hydrophobic environmental hormone 17ß-estradiol in aqueous solutions. First, the corresponding characterization of prepared materials was implemented by myriads of methods (e.g, atomic force microscopy), transmission electron microscopy, scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction and Raman spectroscopy. Next, the effect of the PN on the degradation efficiency was systematically investigated. Apparently, the doping of TiO2 by PN significantly enhanced its photocatalytic and adsorption properties with the addition of PN, compared to that in the absence of TiO2. That is the addition improved the adsorption capability of the composite. The optimal PN weight content was found to be 0.5%. However, the photo degradation efficiency gradually decreased when the PN content increased further. This optimal PN content directly suggested synergistic interactions upon the photo degrading efficiency. Compare to other PN-based photocatalysts mentioned in literature, this PN-based material owned striking advantages, such as higher energy efficiency, greater remove capacity, and superior cost-effectiveness. Further, biotoxicity of the water after treatment decreased was evident by observing the development of zebrafish embryos. In conclusion, the prepared PN-based materials exhibited promising photocatalytic capabilities for removal and biotoxicity reduction of 17ß-estradiol in aqueous solutions.