Physicochemical Properties Of Composites Research Articles

Scaffolds based on β tricalcium phosphate and polyhydroxyalkanoates as biodegradable and bioactive bone substitutes with enhanced physicochemical properties

Polyhydroxyalkanoates (PHAs) are biocompatible and biodegradable bacterial-origin polyesters, which have recently emerged as a potential prosperous coating for bioceramic scaffolds. However, biopolymers often have properties inferior to commercially available polymers, and thus blending seems to be an efficient method to tailor their characteristics. In our study poly(3-hydroxybutyrate) (P(3HB)) and medium chain length PHA (mcl-PHA) blends were used as coatings on β tricalcium phosphate (βTCP) scaffolds. The influence of the coating type on the physicochemical properties of composites was investigated using various techniques such as X-ray diffraction (XRD), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis with differential scanning calorimetry (TG/DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM), wettability measurements, ultra high-performance liquid chromatography with and mass spectrometry (UHPLC-MS) and in vitro studies. It has been demonstrated that blends with various amounts of brittle P(3HB) and viscous mcl-PHA can serve as coatings on βTCP scaffolds, modulating their physicochemical properties. Macroporous scaffolds covered with blends possessed high open porosity (~ 65 vol%) and improved compressive strength (up to 4.9 ± 0.9 MPa). It has been shown that their wettability can be tailored by modifying composition of blends, making the surface more hydrophobic with increasing amount of mcl-PHA. The highest amount of mcl-PHA was shown to significantly influence the degradation of the composites which may be a valuable feature in the case of customized scaffolds for the controlled release of bioactive substances. Moreover, UHPLC-MS analysis revealed that PHAs degrade to hydroxy acids and their oligomers, which may serve as potentially nourishing compounds for surrounding tissues. According to in vitro biocompatibility tests on mouse preosteoblasts, all evaluated scaffolds were nontoxic. The greater the surface hydrophilicity, the better cell adhesion and proliferation were observed.

Structural and physicochemical properties of composites between starch nanoparticles and β-carotene prepared via nanoprecipitation

To apply starch nanoparticles (SNP) as host materials for β-carotene encapsulation, aqueous SNP dispersions (10, 25, 50, and 100 mg/10 mL) and β-carotene in acetone (10, 50, 100, 150, and 200 μg/mL) were mixed. The acetone in the mixture was evaporated to prepare SNP and β-carotene composites, which were homogeneously dispersed in aqueous media with over 90 % solubility. When SNP content was higher than 50 mg, over 80 % of β-carotene was encapsulated in the composite matrix. X-ray diffraction, nuclear magnetic resonance spectroscopy, and transmission electron microscopic analyses confirmed the micellar-shaped composite particles with diameters <120 nm and an amorphous structure. High SNP content in the composites enhanced β-carotene stability under extremely hot and acidic conditions as well as against ultraviolet rays and oxidation reactions. The encapsulated β-carotene was not readily released in simulated gastric fluid, but was gradually released in simulated intestinal fluid via SNP digestion in the composites.

The fabrication of halloysite nanotube-based multicomponent hydrogel scaffolds for bone healing.

Bone tissue engineering, as an alternative for common available therapeutic approaches, has been developed to focus on reconstructing of the missing tissues and restoring their functionality. In this work, three-dimensional (3D) nanocomposite scaffolds of polycaprolactone-polyethylene glycol-polycaprolactone/gelatin (PCEC/Gel) were prepared by freeze-drying method. Biocompatible nanohydroxyapatite (nHA), iron oxide nanoparticle (Fe3O4) and halloysite nanotube (HNT) powders were added to the polymer matrix aiming to combine the osteogenic activity of nHA or Fe3O4 with high mechanical strength of HNT. The scanning electron microscope (SEM) methods was utilized to characterize the nanotube morphology of HNT as well as nanoparticles of Fe3O4 and nHA. Prepared scaffolds were characterized via Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and SEM methods. In addition, the physical behavior of scaffolds was evaluated to explore the influence of HNT on the physicochemical properties of composites. Cell viability and attachment were investigated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay and SEM on human dental pulp-derived mesenchymal stem cells (h-DPSCs) in-vitro. Cell proliferation was observed without any cytotoxicity effect on h-DPSCs for all examined scaffolds. Alizarin red (ARS) and alkaline phosphatase (ALP) staining were carried out to determine the osteoconductivity of scaffolds. The data demonstrated that all PCEC/Gel/HNT hydrogel scaffolds supported osteoblast differentiation of hDPSCs with moderate effects on cell proliferation. Moreover, PCEC/Gel/HNT/nHA with proper mechanical strength showed better biological activity compared to PCEC/Gel/HNT/Fe3O4 and PCEC/Gel/HNT scaffolds. Therefore, this study suggested that with proper fillers content, PCEC/Gel/HNT nanocomposite hydrogels alone or in a complex with nHA, Fe3O4 could be a suitable candidate for hard tissue regeneration.

Effectiveness of a biogenic composite derived from cattle horn core/iron nanoparticles via wet chemical impregnation for cadmium (II) removal in aqueous solution

The objective of the current study was focused on the potential adsorption capability of a biogenic hydroxyapatite/iron nanoparticles-based composite tailored for the elimination of toxic pollutant, Cd(II) ions. Morphological along with physicochemical properties of composites were analyzed by different techniques including Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). It has been noticed an increase in cell parameters of prepared composites with an increase in the amount of nanoparticles. The best adsorbent was found to be the one with a 5% amount of nanoparticles (P400Fe(5%)). The kinetics studies have shown that the pseudo-first-order-models were in good agreement for the removal of Cd(II) ions onto P400Fe(5%) at any concentration, suggesting a physisorption mechanism. Besides, isotherms analysis has consistently revealed Freundlich as the model better explained the isotherm data, with a maximum removal capacity of 392.3 mg g−1, higher compared to many adsorbents. Thermodynamically, the removal adsorption process of Cd(II) ions onto the composite favorable, exothermic, and spontaneous. The regeneration study has been also investigated with reusability used until four cycles. The overall results pointed out the suitability and efficiency of the prepared biogenic composite for the elimination of metal pollutants in wastewater.

Preparation of Biocomposite Material with Superhydrophobic Surface by Reinforcing Waste Polypropylene with Sisal (Agave sisalana) Fibers

Nowadays, eco-friendly, renewable, and biodegradable biocomposites are among the most intensely sought materials of choice. Biocomposites have been widely used as substitutes for plastics due to their biodegradability. However, biocomposite materials absorb water and ultimately loss mechanical properties that affect service life. In this work, a biocomposite material with superhydrophobic surface was prepared by reinforcing waste polypropylene with sisal (Agave sisalana) fibers. The biocomposite was prepared by mixing waste polypropylene and sisal fiber with 5%, 10%, 15%, and 20% fiber loading. Based on characterization results, the composite with 15% fiber content is considered as optimum ratio. Physicochemical properties of composites were evaluated using standard American Society of Testing Materials including biodegradability test and chemical resistance test. The biodegradability of the composite before surface modification was determined by calculating weight loss and found to be 0.11%, 4.62%, 7.15%, and 10.97% for 0%, 5%, 10%, and 15% fiber loadings, and their tensile strength was 10.25 ± 0.05 , 14.47 ± 0.02 , 14.48 ± 0.02 , and 19.90 ± 0.09 MPa for 0%, 5%, 10%, and 15% fiber content, respectively. The surface of the composite was modified for hydrophobicity by etching the surface with chromic acid followed by treating with stearic acid. The FTIR and the SEM images of unmodified and modified (superhydrophobic) surface of composites clearly state the significant difference in chemical composition and surface structure, respectively. The superhydrophobicity of the surface-modified biocomposite was defined by its self-cleaning and low wet ability properties.

Prediction of G Protein-Coupled Receptors With CTDC Extraction and MRMD2.0 Dimension-Reduction Methods.

The G Protein-Coupled Receptor (GPCR) family consists of more than 800 different members. In this article, we attempt to use the physicochemical properties of Composition, Transition, Distribution (CTD) to represent GPCRs. The dimensionality reduction method of MRMD2.0 filters the physicochemical properties of GPCR redundancy. Matplotlib plots the coordinates to distinguish GPCRs from other protein sequences. The chart data show a clear distinction effect, and there is a well-defined boundary between the two. The experimental results show that our method can predict GPCRs.

Preparation of Multicomponent Biocomposites and Characterization of Their Physicochemical and Mechanical Properties

This work focused on a mutual comparison and characterization of the physicochemical properties of three-component polymer composites. Binary polyaniline–chitosan (PANI–CHT) composites were synthesized by in situ polymerization of PANI onto CHT. Ternary composites were prepared by blending with a third component, polyvinyl alcohol (PVA). Composites with variable PANI:CHT (25:75, 50:50 and 75:25) weight ratios were prepared whilst fixing the composition of PVA. The structure and physicochemical properties of the composites were evaluated using thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)) and spectroscopic methods (infrared (IR), nuclear magnetic resonance (NMR)). The equilibrium and dynamic adsorption properties of composites were evaluated by solvent swelling in water, water vapour adsorption and dye adsorption isotherms. The electrical conductivity was estimated using current–voltage curves. The mechanical properties of the samples were evaluated using dynamic mechanical analysis (DMA) and correlated with the structural parameters of the composites. The adsorption and swelling properties paralleled the change in the electrical and mechanical properties of the materials. In most cases, samples with higher content of chitosan exhibit higher adsorption and mechanical properties, and lower conductivity. Acid-doped samples showed much higher adsorption, swelling, and electrical conductivity than their undoped analogues.

Novel biochar@CoFe2O4/Ag3PO4 photocatalysts for highly efficient degradation of bisphenol a under visible-light irradiation

In the study, a series of novel Z-scheme biochar@CoFe2O4/Ag3PO4 photocatalysts were synthesized and employed to degrade bisphenol A under visible light irradiation (λ ≥ 420 nm). The structural morphology, optical properties and physicochemical properties of composites were characterized by means of TEM, XRD, FT-IR, XPS, UV–Vis, BET, EIS and VSM analysis. The photocatalytic performances of the photocatalysts were evaluated systematically. The MBA-3 photocatalyst exhibited the highest photocatalytic and mineralization ability within 60 min among all photocatalysts, 91.12% and 80.23%, respectively. After four cycles, the degradation of BPA still kept the photocatalytic activity of 73.94%, and the removal rate of TOC remained 58.96%. Moreover, the active species in the photocatalytic process were evaluated, and we proposed the Z-scheme photocatalytic mechanism for highly efficient degradation of BPA. According to the GC-MS results, the photodegradation pathway of BPA is also suggested. The present study has provided a valuable way of using the magnetic biochar in the design of new and efficient system for the degradation of organic pollutions in waste water.

Formation of active zero-valent iron by simple co-grinding with CaCO3 to protect fresh active surface for efficient removal of hexavalent chromium

A novel composite material consisting of zero-valent iron (ZVI) and CaCO3 was successfully prepared through a simple grinding operation. The as-synthesized ZVI/CaCO3 composites were applied to the reduction precipitation of hexavalent chromium (Cr(VI)) and a tremendous improvement in reaction capacity was obtained compared with raw ZVI and ground ZVI sample without CaCO3 addition. Many factors of the grinding operation and ZVI/CaCO3 mass ratios were investigated to evaluate material properties and to study reaction mechanism. A high removal efficiency of 99.68% within just 30 min on Cr (VI) (10 mg/L) was obtained by the ZVI/CaCO3 composite with ZVI mass ratio at 30 wt%. X-ray diffraction (XRD), Fourier transformed infrared (FTIR), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) were used to investigate the chemical constitution and physicochemical properties of composites before and after the reaction. Addition of CaCO3 played very important role in both grinding iron particles into fine powders and protecting the fresh surface of active ZVI to enable the superior performance as zero-valent iron. Besides the environment-friendliness of the process itself without any pollutant emission, waste solid materials containing iron particles may serve as the starting sample to decrease the product cost.

Physicochemical Properties of Calcium Phosphate–Chitosan Composites and Scaffolds

This paper reports a study of the physicochemical properties of composites and scaffolds (synthesized for the first time) based on dicalcium phosphate dihydrate (DCPD, brushite), hydroxyapatite (HA), and chitosan. The crystallite size of the composites has been shown to increase with increasing chitosan concentration in the starting solution. The first technique has been proposed for the fabrication of scaffolds based on brushite, HA, and chitosan gel. The pore size in the scaffolds has been shown to increase with increasing brushite content. Raising the calcination temperature improves the stability of the scaffolds, whereas the composites persist in the form of powder independent of heat treatment. Analysis of the dissolution behavior of the synthesized composites and scaffolds in an isotonic solution indicates that, in the DCPD–chitosan system, the dissolution rate decreases with increasing chitosan concentration, whereas the HA–chitosan system exhibits opposite behavior.

In situ synthesis and characterization of hydroxyapatite/natural rubber composites for biomedical applications

In this work, a biomimetic synthesis reaction for the production of hydroxyapatite (HA)/natural rubber (NR) composites is presented. HA was synthesized in the presence of solubilized NR in tetrahydrofuran (THF), which permits that negatively charged domains in proteins and lipids in NR work as nucleation sites for hydroxyapatite. The mechanical and physicochemical properties of composites containing 10, 20 and 30wt% HA were studied. NR influenced HA crystallite morphology, shape and size and was able to disperse the HA particles in THF. The dispersion of HA in the composites promoted the enhancement of mechanical properties and loss of solubility of composites, which is believed to be macroscopic manifestations of the physical adsorption of NR to HA particles, known as the bound rubber phenomenon. Preliminary cell studies indicated that HepG2 cells presented viabilities ranging from 71.6 to 91.3%, with cell proliferation positively influenced by HA content at shorter culture times. The good dispersion of HA in the composites is expected to improve NR bioactivity and direct its use towards bone applications.

Synthesis and physico-chemical properties of composites based on nanostructured zinc oxide and polyaniline

ABSTRACTComposites based on polyaniline and nanostructured zinc oxide were synthesized by mechanical mixing and the method of in situ polymerization and their physicochemical properties were studied. The electrical conductivity, surface structure and morphology of composites have been investigated. It is shown that the method of synthesis and quantity of filler affects the morphology and physicochemical properties of composite materials. An addition of various quantities of mineral filler to composite allows controlling conductivity of obtained materials. XRD-analysis of composite materials synthesized by in situ polymerization confirms the interaction of the components of the composite.

Production Technology and Physicochemical Properties of Composition Containing Surfactant Proteins

Production Technology and Physicochemical Properties of Composition Containing Surfactant Proteins

The use of PAP-2 aluminum dust to fabricate powder composite materials: the features of technology, structure and physicomechanical composites. Part 1. Manufacturing approaches that provide the creation of composite materials and applied procedures for de

Composites Al/Al2O3 (lamellar cermet matrix)–filling agent (discrete metallic filaments, duralumin chips, graphite particles, fused corundum grains, kaolin filaments, and technical alumina spherolites) are fabricated. Industrially produced PAP-2 aluminum powder, which consists of scaled particles with stearin coating (specific surface of the powder is 4,1322 m2/g, its particle sizes vary from 0,03 to 10 μm), was used to form the lamellar cermet matrix. In order to form the composites, the following production operations were used: heat treatment of PAP-2 powder in air to burn-out stearin from the particle surface and substitute it by alumina film, mixing the formed powder product with the filling agent, pressing, and reaction sintering the powder billets in a filtration burning mode in air. A new approach based on the chemical reaction of stearin saponification is proposed to fabricate the Al/Al2O3 composite. In this reaction, stearin on the surface of aluminum particles reacts with caustic soda resulted from the hydrolysis of diluted liquid glass introduced into initial powder. The reaction products (sodium stearate and glycerin) decompose during subsequent heat treatment in air with the formation of coke residue on the particle surface. Physicochemical properties of composites were determined using standard and generally accepted procedures.

Bioactivity and Physico-Chemical Properties of Composites on Basis of Hydroxyapatite with Lactic and Glycolic Acids Oligomers

A new methodin situfor producing of biocompatible composites based on hydroxyapatite and oligomers of lactic and glycolic acid is described. Their thermo-mechanical, physical-chemical and biological properties are studied as well. The formation of bonds between hydroxyapatite with lactic and glycolic oligomers in composites are confirmed by IR spectroscopy of the samples, including those obtained in the Soxhlet apparatus. The formation of calcium-phosphate layer on the composite's surface containing hydroxyapatite was shown by SBF-investigation. The scaffolds based on lactic acid oligomer do not stimulate formation of a calcium-phosphate layer and they are subjected to destruction by the way of hydrolysis.

Synthesis, characterization and photocatalytic behavior of TiO2–SiO2 mesoporous composites in hydrogen generation from water splitting

TiO2–SiO2 mesoporous composite photocatalysts with different proportions (in wt%) of TiO2 and SiO2 (TiO2–SiO2 = 20:80, 40:60, 60:40, 80:20 and 100:0) were prepared by loading TiO2 on as-synthesized Si–MCM-41 using sol–gel method. The physicochemical properties of composites were investigated by powder X-ray diffraction, N2 adsorption–desorption measurements, transmission electron microscopy and UV–Vis diffuse reflectance spectroscopy. It is revealed that the titanium species are dispersed as TiO2 having interaction with the surface of the support. Even at high TiO2 loading, the mesostructural feature of MCM-41 was found to be intact without pore blockages. The change in morphology of TiO2 particle was observed with increase in TiO2 loading which may be due to different environment for the growth of TiO2. The photocatalytic evaluation of composites was carried out in production of hydrogen by water splitting. Among the prepared samples, mesoporous composite containing 60 % TiO2 (MTi60) has shown the best results (0.08805 mmol of H2/h/g of TiO2) compared to other composite photocatalysts. The catalytic performance of this sample was further enhanced (~8 times) after loading 1 % Pt in water splitting (0.70161 mmol of H2/h/g of TiO2). 1 % Pt loaded on pure TiO2 (MTi100) showed hydrogen evolution of the magnitude 0.26 mmol of H2/h/g of TiO2. TiO2–SiO2 mesoporous composite photocatalyst showed much higher activity (~1.9 times) than amorphous silica-embedded titania catalyst having same composition.

Sintering and physicochemical properties of compositions in the SiC–Al 2O 3–La 2O 3–Cr 2O 3 system II. Oxidation resistance of pressureless sintered compacts in the SiC–Al 2O 3–La 2O 3–Cr 2O 3 system

Compacts prepared from SiC (70–55 wt%), Al 2O 3 (10 wt%) and LaCrO 3 (20–35 wt%) by pressureless sintering in carbon at 1700°C were studied for their oxidation resistance in air at 1300, 1400 and 1500°C. The oxidation resistance of the material at 1500°C was dependent on the quantity of La 2O 3–Al 2O 3–SiO 2 melt, which diffused from inside to the surface of the compacts. Instead, chromium compounds were retained in the material and barred the melt diffusion. Nevertheless, at 1300°C, La 2O 3 of the compacts reacted with SiO 2 and gave a dependable protective layer of lanthanum silicates.