Styrene butadiene-based blends containing waste rubber powder: Physico-mechanical effects of mechanochemical devulcanization and gamma irradiation

Waste rubber (WR) powder was introduced in a two-roll mill in the presence of various ratios of curatives to develop sheets of devulcanized waste rubber (DWR). The selected product was investigated by FTIR, TGA and SEM. In a roll mill and hot press, styrene butadiene rubber (SBR) gum was differentially replaced by DWR feed ratios, and thereafter irradiated with gamma rays. The mechanical parameters of the developed blend were examined. Oil resistance and thermogravemetric behavior were discussed. Remarked improvement in the mechanical, thermal and physical parameters of SBR was generally determined by the incorporation of DWR and gamma irradiation.     

Electrochemical characterization and transport properties of polyvinyl chloride based carboxymethyl cellulose Ce(IV) molybdophosphate composite cation exchange membrane

The polyvinyl chloride (PVC) based carboxymethyl cellulose Ce(IV) molybdophosphate composite membrane are prepared and characterized by the Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and thermogravimetric analysis (TGA) studies. The inorganic–organic composite membrane was found to be crystalline in nature with consistent arrangement of particles and indicating no sign of visible cracks. The FTIR spectra verify the binding of organic polymer with inorganic component. The membrane was found to be cation-selective. The order of surface charge density for uni-univalent electrolytes solution was found to be KCl > NaCl > LiCl.     

Effect of additives on the properties and performance of cellulose acetate derivative membranes in the separation of isopropanol/water mixtures

In this work, various cellulose acetate (CA) membranes for pervaporation were prepared by the incorporation of different additives, i.e. polyethylene glycol-600 (PEG-600), propylene glycol (PG), and ethylene glycol (EG) to enhance the separation of isopropanol (IPA)/water mixtures. These membranes were characterized by FTIR, DSC, TGA, SEM and UTM. Each additive was responsible for its characteristic effect on the membrane morphology, mechanical strength, permeation flux and separation factor. The SEM micrograph showed that the additives were evenly dispersed in the membrane matrix with the formation of dense membranes. The UTM tests for the membrane reveled that both the Young's Modulus and tensile strength increased with the increase in additive contents. TGA studies for the CA/PEG blend membrane exhibited the highest thermal stability as compared to the CA/PG and CA/EG blends. For each of these synthesized membranes, the separation factor decreased while the permeation flux increased with the increase in additive contents, while the CA/PG membrane with 20 wt.% additive content showed highest permeation flux of 452.27 g/m²h.     

A study on the characteristics of a rubber blend of fluorocarbon rubber and hydrogenated nitrile rubber

In this study, the physical and chemical characteristics of a rubber blend of fluorocarbon rubber (FKM) and hydrogenated Nitrile Butadiene rubber (HNBR) were investigated based on the blend ratio for the purpose improving thermal resistance of HNBR and the low-temperature resistance of FKM. The blended FKM and HNBR materials showed better heat resistance, oil resistance, and fuel resistance than those of the 100 phr HNBR materials. Blended materials with added compatibilizer (KBM503) showed improved basic physical properties than those of the materials without the agent. This result agreed with a scanning electron microscopy image. The thermal properties of the blended materials based on the FKM and HNBR blend ratio were studied by Thermo Gravimetric Analysis (TGA) and differential scanning calorimetry (DSC). The TGA results showed improved heat resistance characteristics for the blended materials than those of the HNBR materials. The DSC results also showed improved characteristics of low temperature resistance with increasing HNBR contents.     

Synthesis,physico-chemical characterization,transport phenomena and antibacterial activity of polystyrene based barium phosphate composite membrane

The polystyrene based barium phosphate composite membrane was prepared by co-precipitation method. The composite membrane has been characterized on the basis of scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR) and thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies. Ion-exchange capacity, water uptake, porosity, thickness and stability studies were also carried out to determine the preliminary ion-exchange properties of the composite membrane. The order of transport number of cation for univalent electrolytes solution was found to be KCl < NaCl < LiCl. The antibacterial activity of composite membrane was investigated against some bacteria.     

The effect of gamma irradiation on mechanical,thermal and morphological properties of glass fiber reinforced polyethylene waste/reclaim rubber composites

Composites of waste polyethylene (WPE), collected from municipal solid waste/recycled waste rubber powder (RWRP) reactive compatibilizing agent, maleic anhydride (MA) and glass fiber (GF) up to 20 wt%, prepared by melting and irradiated with gamma-rays up to 150 kGy have been studied. Tensile strength (T_S), elongation at break (E_b), elastic modulus, hardness, thermal and morphological parameters of the irradiated composites were investigated. The examined mechanical properties have been found to improve largely with filler content. Interesting E_b behavior has been detected for the irradiated composites loaded up to ∼10 wt% GF and has been basically discussed in view of matrix crystallinity and morphology. TGA thermograms of unirradiated composites revealed enhanced thermal stability than that reported for the blend whereas comparatively slight improvement has been demonstrated by irradiation. Whereby insignificant alteration in T_m values was observed by loading or irradiation, yet ΔH_m maximum of 3.41 J/g, indicated for the 5 wt% GF irradiated composite with an integral dose of 75 kGy, emphasizes the influence of the relatively moderate load and dose levels on matrix stability. The phenomenon has been confirmed by the respective SEM micrographs.     

PVC based polyvinyl alcohol zinc oxide composite membrane: Synthesis and electrochemical characterization for heavy metal ions

The polyvinyl chloride (PVC) based polyvinyl alcohol zinc oxide composite membrane was successfully prepared by solution casting technique. Membrane properties were studied in terms of water uptake, porosity, thickness, ion-exchange capacity and swelling. The physico-chemical characterization of the material was studied using Fourier transform infrared (FTIR) spectroscopy, thermogravimetry analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies. The important application of this composite ion-exchange membrane is in environmental separation of heavy metal ions transport. The increasing order of transport number of cation as HgCl₂ < PbCl₂ < CdCl₂.     

Synthesis and characterization of polyaniline–titanium(IV)phosphate cation exchange composite: Methanol sensor and isothermal stability in terms of DC electrical conductivity

Electrically conductive composite of polyaniline–titanium(IV)phosphate (PANI–TiP) was synthesized by sol–gel method. The obtained composite was characterized by using Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The composite showed good ion-exchange capacity and isothermal stability in terms of DC electrical conductivity retention at an ambient conditions below 100 °C. The composite material was investigated as alcohol vapors sensor and compared with blank polyaniline. The results showed that the composite was more selective and sensitive towards methanol vapors.     

Synthesis and characterization of TiO2 nanoparticles

TiO₂ nanoparticles were synthesized by thermal decomposition of a precipitate obtained from a precursor solution of titanium isopropoxide (IV) and isopropyl alcohol. The as-prepared precipitate was heated at various temperatures and the obtained samples were morphologically, texturally and structurally characterized using TGA–DTA, gas adsorption, SEM, XRD and FTIR. The UV–vis radiation absorption and the photocatalytic activity also were verified. The TiO₂ sample heated at 300 °C shows the best results to be applied as blocker in solar skin protector.     

Thermal degradation study of fire resistive coating containing melamine polyphosphate and dipentaerythritol

A melamine polyphosphate (MPP)/dipentaerythritol (DPER) mixture was used as fire retardant additives for preparing waterborne intumescent fire resistive coating. The thermal degradation of the MPP/DPER mixture and of the coating was studied by TGA and FTIR. The resulting char of the coating was investigated by XPS, SEM and energy dispersive spectroscopy (EDS). The results showed that the thermal degradation behavior of the MPP/DPER mixture was similar to that of the coating. They decomposed to nonflammable gases, and formed intumescent char layer containing phosphorus oxide at high temperature. The EDS results proved that the resulting char was gradually oxidized with the temperature increase. The SEM micrographs showed that the average cell size of the char layers became bigger and the cell size distribution became wider as the temperature increased from 500 °C to 800 °C, and this non-uniform char layer could damage the fire protection of the coating.     

Optical and thermo-mechanical properties of composite films based on fish gelatin/rice flour fabricated by casting technique

Packaging films based on fish gelatin-rice flour (FG-RF) at different blend ratios (FG-RF ≈ 10:0, 8:2, 6:4, 5:5 and 0:10, w/w) using 30% (w/w) glycerol as plasticiser were prepared and characterised. FG-RF composite films exhibited lower tensile strength (TS) and elongation at break (EAB), compared to FG film (P < 0.05). Higher water vapour permeability (WVP), but lower water solubility (WS) was obtained for FG-RF composite films having the increased proportion of RF (P < 0.05). Light transmission in ultraviolet (UV) and visible regions (200–800 nm) was lowered in all FG-RF composite films, indicating excellent light barrier characteristics. Based on FTIR spectra, significant changes in molecular structure and lower intermolecular interactions between FG and RF molecules were found in FG-RF (8:2) composite film. Thermogravimetric analysis indicated that FG-RF (8:2) composite film had only 7.61% (w/w) heat-stable mass residues in the temperature range of 50–600 °C. DSC thermograms suggested that FG-RF (8:2) composite film consisting of amorphous/microcrystalline layers of partially miscible aggregated junction zones and the coexisting two different order phases of unbound domains. SEM micrographs elucidated that FG-RF (8:2) composite film was rougher than FG film, but no signs of phase separation between film components were observed, thereby confirming their potential use as packaging material.     

Electron beam irradiation of polycarbonate reinforced acrylonitrile butadiene rubber

The effects of electron beam irradiation and polycarbonate (PC) concentration on the properties of acrylonitrile butadiene rubber (NBR) were investigated. The electron beam irradiation doses were from 25 to 150 kGy, whereas the PC contents were from 10 to 30 phr. It was found that the mechanical properties of NBR such as tensile strength (TS), hardness and tear strength (Ts) were remarkably improved by the incorporation of PC, while elongation at break (E_b) and thermal properties were decreased. However, the improvement in TS of NBR/PC blends was strongly dependant on PC content, in which maximum improvements need higher doses. On the other hand, the maximum value of Ts for all the blend ratios was at 25 kGy, whereas the hardness increases with increasing irradiation dose. Moreover, it was observed that the fuel resistance of NBR/PC was higher than NBR and decreases by increasing the content of PC.     

Preparation and characterization of 3-chloropropyl polysiloxane-based heat-curable silicone rubber using polyamidoamine dendrimers as cross-linkers

A series of high-temperature vulcanization (HTV) silicone rubber was prepared with polyamidoamine (PAMAM) dendrimers as concentrative cross-linkers and polysiloxane containing 3-chloropropyl groups (CPPS) as gums in a novel curing system. The curing, mechanical, and thermal properties of this novel HTV silicone rubber (MCSR) were studied through rheometry, mechanical testing, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The curing process was analyzed on the basis of the cure curves obtained by rheometry. The optimal conditions to prepare MCSR were determined by changing curing conditions, including cross-linker concentration, curing temperature, and postcuring temperature. MCSR exhibited a tensile strength of 9.34 MPa and a tear strength of 47.71 kN/m when the molar ratio of [3-chloropropyl]/[N–H] was 1:1.5. These excellent mechanical properties were attributed to the concentrative cross-linking effect from PAMAM dendrimers. Meanwhile, the mechanical properties slightly changed as the generation of PAMAM dendrimers increased because of steric hindrance. In addition, TGA results indicated that MCSR was thermally stable in a nitrogen atmosphere even at high degradation temperatures, such as T_{5 wt.% loss} (MCSR-3) = 451.7 °C and T_{50 wt.% loss} (MCSR-3) = 659.0 °C. DSC analysis revealed that a glass transition peak followed by a melt was identified for MCSR at − 160 °C to 30 °C. The experimental results showed that using PAMAM dendrimers as cross-linkers is a practical way to obtain silicone rubber with excellent properties.     

Preparation and performance of a heat-resistant organic adhesive obtained via a liquid SiC precursor

A heat-resistant organic adhesive rich in active SiH bonds and CHCH₂ bonds has been synthesized by modifying polymethylsilane with D4Vi. The structure and properties of the adhesive have been investigated by FTIR, GPC, TGA, XRD, bonding strength tests, and SEM. The results show that the obtained adhesive exhibits outstanding thermal stability and bonding properties. The ceramic yields of the adhesive treated in Ar or in air at up to 1200 °C were measured as 81% and 90.6%, respectively. The adhesive can maintain an amorphous state even when heat-treated at 1200 °C for 2 h in air. The room temperature shear strength of the adhesive was measured as 14.9 MPa, and this increased to a maximum value of 31.7 MPa after heat-treatment at 1000 °C for 2 h.     

Carbon nanotubes: Amino functionalization and its application in the fabrication of Al-matrix composites

Al-matrix composites reinforced with amino-functionalized multiwalled carbon nanotubes (fCNTs) have been fabricated using the powder metallurgy process. Using this method fCNTs (1.5 wt.%) were dispersed in Al powder by high energy ball milling. Al–fCNTs composites (1.5 wt.%) were fabricated by the consolidation of powders at 550 MPa followed by sintering at 620 °C under a vacuum of 10^? 2 Torr for 2 h. Functionalization of the nanotubes was carried out by ball milling multi-walled carbon nanotubes (MWCNTs) in the presence of ammonium bicarbonate. It was observed that the dispersion of fCNTs in Al-matrix was much higher than those of non-functionalized MWCNTs. Microhardness measurements showed that a microhardness value of about 400 kg/mm² could be obtained for Al-matrix composites loaded with 1.5 wt.% fCNTs. Microstructure observations using scanning electron microscopy (SEM) and high-resolution electron microscopy (HRTEM) confirmed that the sintered composites had a good dispersion of fCNTs in Al matrix and they do not agglomerate with each other. Further, the HRTEM characterization of these composites revealed the formation of a thin transition layer of Al₄C₃ between fCNTs and Al matrix, which is believed to be responsible for load transfer from Al matrix to fCNTs. A thorough characterization of MWCNTs and fCNTs synthesized in the present work was carried out using XRD, SEM, TGA, HRTEM, FTIR, SIMS and Raman spectroscopy.     

Preparation and properties of a novel precursor-derived Zr-C-B-N composite ceramic via zirconocene and borazine

A novel preceramic polymer polyzirconocenyborazane (PZCBN) was synthesized by the polymerization of Bis(cyclopentadienyl)zirconium divinyl and borazine, introducing Zr, B, C, N together. The formation and concentration of elements Zr, C, B, N in the precursor and ceramic were detected through FTIR NMR, XRD, SEM and TEM. From the analysis, the Cp₂Zr(CH?CH₂)₂ and borazine linked together via the addition reaction between C?C and B-H. And after pyrolysis at 1200 °C, the precursor turned to ZrC/ZrB₂/BN composite ceramics, with a yield of 52 wt%. EDX resulted showed that the elements were well dispersed in the ceramics. According to SEM and TEM, the ceramic had a relatively dense structure with nano crystalline areas of ZrC embedded in the amorphous Zr-C-B-N matrix. TGA in air demonstrated that the ceramic had a favorable property on oxidation resistance.     

In-situ FTIR analyses of bentonite under high-pressure

The stability of bentonite is of particular interest for containment barriers in nuclear waste disposal facilities. However, very little is known about the stability of montmorillonite (the major component of bentonite) under high-pressure (HP) conditions. The objective of this work is to investigate the stability of montmorillonite under HP conditions, using a sample of bentonite in which the major component is a dioctahedral calcium montmorillonite. This montmorillonite was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), specific surface area (SA), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). HP experiments up to 7.7 GPa at room temperature (RT) were performed using toroidal chambers (TC). The samples were characterized by XRD after the HP processing. In-situ FTIR analyses were performed in the samples inside a diamond anvil cell (DAC) up to 8 GPa (dispersed in KBr) and up to 13 GPa (pure bentonite). In-situ FTIR measurements inside the DAC showed that montmorillonite was stable despite a reversible deformation in the Si–O bond and did not lose water up to 13 GPa. XRD analysis of the samples processed at 8 GPa at RT inside the TC showed no marked modification in the (001) reflections and b-parameter (060) reflections of montmorillonite induced by high pressure. The obtained results indicated that montmorillonite remained stable under high pressure conditions.     

Activation of Mg–Al hydrotalcite catalysts for transesterification of rape oil

Mg–Al hydrotalcites with different Mg/Al molar ratios were prepared and characterized by powder X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), thermogravimetric apparatus and differential thermal analysis (TGA-DTA) and scanning electron micrograph (SEM). It was confirmed by XRD that the materials had hydrotalcite structure. The hydrotalcite catalyst calcined at 773 K with Mg/Al molar ratio of 3.0 exhibited the highest catalytic activity in the transesterification. In addition, a study for optimizing the transesterification reaction conditions such as molar ratio of the methanol to oil, the reaction temperature, the reaction time, the stirring speed and the amount of catalyst, was performed. The optimized parameters, 6:1 methanol/oil molar ratio with 1.5% catalyst (w/w of oil) reacted under stirring speed 300 rpm at 65 °C for 4 h reaction, gave a maximum ester conversion of 90.5%. Moreover, the solid catalyst could be easily separated and possibly reused.     

Deposition of SiC/Si coatings in a microwave plasma-assisted spouted bed reactor

Silicon carbide (SiC) layers were deposited onto alumina particles in a microwave plasma-assisted spouted bed reactor using methyltrichlorosilane (MTS) and hydrogen mixtures, in argon, as precursor gas feed. The operating parameters studied were enthalpy, gas composition, and pressure. Microwaves were guided from a generator, operating at 2.45 GHz, along a rectangular waveguide intersecting a quartz tube, acting as the reaction zone. A graphite nozzle at the bottom of the tube facilitated the spouting action. Growth rates varied from 50 to 140 μm/h. Overall results indicate that the optimal region for SiC deposition requires relatively high enthalpy (～5 MJ/kg) and pressure (>?60 kPa) conditions, with hydrogen-to-MTS ratios ～5:1. The quality (i.e. crystallinity, particle size, Si/C ratios) of the layers improve at these conditions, at the cost of decreased deposition rates. Characterisation was done by XRD, FTIR, XPS, SEM, TEM and EDX, which assisted in developing colour and morphological charts to indicate the changes as a function of changing operating parameters. A microwave plasma spouted bed reactor is demonstrated to be a viable alternative technique for SiC layer deposition onto microspheres.     

Microwave-induced combustion process variables for MgO nanoparticle synthesis using polyethylene glycol and sorbitol

In this study, MgO nanoparticles were prepared by microwave-induced combustion synthesis of magnesium nitrate (as oxidant and MgO precursor) and polyethylene glycol and sorbitol as fuels. The effects of various parameters including the aging time of the precursor gel before combustion, microwave power and fuel-to-oxidant ratio were investigated. Microwave was applied to homogeneously heat the precursor gel. The temperature profile and the composition of the released gases during the combustion process and the carbonaceous deposits on the MgO nanoparticles were studied by FTIR, TGA, Raman spectroscopy, and temperature programmed oxidation (TPO). The MgO samples were calcined at 400 °C for 3 h and characterized using SEM, TEM, BET and PXRD. MgO nanoparticles as small as 4.1 nm were formed using 20% excess of sorbitol and 40% excess of polyethylene glycol as the fuels.