Modification of physiochemical properties of copra meal by dilute acid hydrolysis

Coconut residue or copra meal (CM), a by‐product after pressing cream and oil out of the coconut meat, is a good source of dietary fibre (DF), but high water‐holding capacity (WHC) of CM limits the quantity of fibre incorporated into food products. This study focused on the modification of CM physiochemical properties using acid hydrolysis to improve its potential utilisation as source of food fibres or low‐calories bulk ingredients in food applications. Acid hydrolysis using 0.5% HCl significantly reduced swelling capacity (SC) and water retention capacity, whereas bulk density (BD) and soluble DF content of the modified CM significantly increased. Monosaccharide composition profile, gel penetration profile and FT‐IR spectra indicated the destruction of CM matrix structure. This destruction increased compactness of the structure and lessened the ability of CM to hold water. Substituting the modified CM for wheat flour in bread and cookies significantly improved bread and cookies qualities compared with the use of the untreated CM. Response surface methodology showed that HCl concentration, hydrolysis temperature and time influenced properties of the modified CM. The models predicting their relationships were also generated.     

Production of nano‐calcium carbonate from shells of the freshwater channeled applesnail,Pomacea canaliculata,by hydrothermal treatment and its application with polyvinyl chloride

The use of naturally renewable shells of the freshwater channeled applesnail, Pomacea canaliculata, as a filler to replace commercial calcium carbonate (CaCO₃) was investigated in this study. Ground P. canaliculata shell particles were converted to nano‐CaCO₃ particles by the displacement reaction of calcium chloride in sodium carbonate solution followed by hydrothermal treatment at 100°C for 1 h to synthesize nano‐CaCO₃ with particle sizes of 30–100 nm in diameter. The mechanical properties, in terms of the tensile strength, elongation at brake and impact strength, of polyvinyl chloride (PVC) were greatly improved by mixing with nano‐CaCO₃ at 5–10 parts per hundred of resin. Additionally, the presence of nano‐CaCO₃ at the same levels increased the flame resistance and thermal stability of the PVC composite materials. POLYM. COMPOS., 36:1620–1628, 2015. © 2014 Society of Plastics Engineers     

Effects of Reaction Parameters in Catalysis of Glycerol Oxidation by Citrate-Stabilized Gold Nanoparticles

Abstract  

This work describes a catalytic oxidation of glycerol using citrate-stabilized gold nanoparticles (citrate-AuNPs) having a mean diameter of 22 ± 3 nm. A careful product analysis was performed by mean of high-performance liquid chromatography, liquid chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy. Effects of reaction temperature, oxygen pressure, catalyst and reactant concentration, and NaOH/glycerol molar ratio on glycerol conversion, and product yields were investigated. The glycerol conversion and glyceric acid yield were optimum when the oxidation was performed using 0.6 M glycerol and NaOH at 80 °C under 3 bar of O₂ pressure in the presence of 50 ppm citrate-AuNPs catalyst for 3 h.     

Comparative behavior of in situ silica generation in saturated rubbers: EPDM and hydrogenated natural rubber

Role of carbon‐carbon double (C?C) bonds content and their position in ethylene‐propylene diene ter‐polymer (EPDM), hydrogenated natural rubber (HNR) and natural rubber (NR) on in situ silica formation using tetraethoxysilane (TEOS) as a silica precursor is comparatively investigated. Glass transition temperature (T_g ) reflecting rubber chain flexibility is found as an important factor for in situ silica generation via swelling method. Despite of similar solubility parameters, NR has higher TEOS‐swelling degree resulting in the higher in situ silica content (30.8 phr) than EPDM (3.50 phr) and HNR (10.4–17.6 phr) due to the higher T_g of EPDM and HNR providing the less chain flexibility to be swollen in TEOS solution. The morphological analysis implies that C?C bonds in saturated rubbers may be agglomeration sites for in situ silica particles. For practical applications, saturated rubbers containing in situ silica/NR vulcanizates showed the improvement of mechanical properties and resistance of thermal and ozone degradation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44748.     

Organosulfonic acid-functionalized mesoporous composites based on natural rubber and hexagonal mesoporous silica

This study is the first report on synthesis, characterization and catalytic application of propylsulfonic acid-functionalized mesoporous composites based on natural rubber (NR) and hexagonal mesoporous silica (HMS). In comparison with propylsulfonic acid-functionalized HMS (HMS-SO₃H), a series of NR/HMS-SO₃H composites were prepared via an in situ sol–gel process using tetrahydrofuran as the synthesis media. Tetraethylorthosilicate as the silica source, was simultaneously condensed with 3-mercaptopropyltrimethoxysilane in a solution of NR followed by oxidation with hydrogen peroxide to achieve the mesoporous composites containing propylsulfonic acid groups. Fourier-transform infrared spectroscopy and ²⁹Si MAS nuclear magnetic resonance spectroscopy results verified that the silica surfaces of the NR/HMS-SO₃H composites were functionalized with propylsulfonic acid groups and covered with NR molecules. After the incorporation of NR and organo-functional group into HMS, the hexagonal mesostructure remained intact concomitantly with an increased framework wall thickness and unit cell size, as evidenced by the X-ray powder diffraction analysis. Scanning electron microscopy analysis indicated a high interparticle porosity of NR/HMS-SO₃H composites. The textural properties of NR/HMS-SO₃H were affected by the amount of MPTMS loading to a smaller extent than that of HMS-SO₃H. NR/HMS-SO₃H exhibited higher hydrophobicity than HMS-SO₃H, as revealed by H₂O adsorption–desorption measurements. Moreover, the NR/HMS-SO₃H catalysts possessed a superior specific activity to HMS-SO₃H in the esterification of lauric acid with ethanol, resulting in a higher conversion level.     

Thiosalicylic acid as a devulcanizing agent for mechano-chemical devulcanization

A mechano-chemical devulcanization process for vulcanized natural rubber (NV) was investigated. Thiosalicylic acid was used as a test devulcanizing agent in comparison to diphenyl disulfide as the reference. The optimum condition for devulcanization of NR vulcanizates (NVs) was found to be grinding of the NV and subsequent mixing with a selected devulcanizing agent at 140°C for 30 min. The degree of devulcanization was indicated by using sol-gel fractions of the devulcanized rubber (DVR). Revulcanized rubber was made by using virgin natural rubber (NR) containing DVR at different ratios. The tensile strength of the DVR/NV composite, after revulcanization, decreased by 5–10%, while the elongation at brake was improved by 5–10% at a DVR content of 5–15%. Devulcanization of industrial truck tires, as a typical sample of industrial products, was also demonstrated for the practical application of this technique.     

Low-temperature particle synthesis of titania/silica/natural rubber composites for antibacterial properties

Composite particles of titania/silica/natural rubber (TiO₂/SiO₂/NR) were prepared and evaluated for their potential antibacterial application. All processes were restricted to a low temperature or a small heating contact time to avoid degradation of the NR. The primary NR particles were synthesized by spray drying and then SiO₂ and TiO₂ were incorporated sequentially by chemical vapor deposition and liquid phase deposition, respectively. The physical and chemical properties were characterized by X-ray diffractometry, scanning electron microscopy with energy dispersive X-ray spectrometry, Fourier-infrared spectroscopy and thermogravimetric analyses. The TiO₂/SiO₂/NR composite particles had a spherical shape with a diameter of about 10 μm, with titania on the outer layer, and showed an effective antibacterial activity of a 99.99% reduction in viable Escherichia. coli and Staphylococcus aureus within 20 min of exposure under fluorescent light. In addition, the particles could be reused with the same level of antibacterial activity for up to three cycles. The structural and antibacterial models of the composite particles are proposed in this work.     

Natural Calcium‐Based Residues for Carbon Dioxide Capture in a Bubbling Fluidized‐Bed Reactor

Used clamshells (Paphia undulata), as a precursor of calcium oxide (CaO) sorbents, were employed for carbon dioxide (CO₂) adsorption in a bubbling fluidized‐bed reactor. To find the optimal calcination conditions, a 2^k experimental design was used to vary the ground clamshell particle size, heating rate, and calcination time at 950 °C under a nitrogen atmosphere. The heating rate was the most significant factor affecting the CO₂ adsorption capacity of the obtained CaO sorbent. The maximum CO₂ adsorption capacity of the CaO obtained under these study conditions was higher than that of commercial CaO.     

Novel mesoporous composites based on natural rubber and hexagonal mesoporous silica: Synthesis and characterization

The present study is the first report on the synthesis and characterization of mesoporous composites based on natural rubber (NR) and hexagonal mesoporous silica (HMS). A series of NR/HMS composites were prepared in tetrahydrofuran via an in situ sol–gel process using tetraethylorthosilicate as the silica precursor. The physicochemical properties of the composites were characterized by various techniques. The effects of the gel composition on the structural and textural properties of the NR/HMS composites were investigated. The Fourier-transform infrared spectroscopy (FTIR) and ²⁹Si magic angle spinning nuclear magnetic resonance (²⁹Si MAS NMR) results revealed that the surface silanol groups of NR/HMS composites were covered with NR molecules. The powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) data indicated an expansion of the hexagonal unit cell and channel wall thickness due to the incorporation of NR molecules into the mesoporous structure. NR/HMS composites also possessed nanosized particles (∼79.4 nm) as confirmed by scanning electron microscopy (SEM) and particle size distribution analysis. From N₂ adsorption–desorption measurement, the NR/HMS composites possessed a high BET surface area, large pore volume and narrow pore size distribution. Further, they were enhanced hydrophobicity confirmed by H₂O adsorption–desorption measurement. In addition, the mechanistic pathway of the NR/HMS composite formation was proposed.     

Increasing the thermal storage capacity of a phase change material by encapsulation: preparation and application in natural rubber

Existing encapsulated organic phase change materials (PCM) usually contain a shell material that possesses a poor heat storage capacity and so results in a lowered latent heat storage density of the encapsulated PCM compared to unencapsulated PCM. Here, we demonstrate the use of a novel microencapsulation process to encapsulate n-eicosane (C20) into a 2:1 (w/w) ratio blend of ethyl cellulose (EC):methyl cellulose (MC) to give C20-loaded EC/MC microspheres with an increased heat storage capacity compared to the unencapsulated C20. Up to a 29 and 24% increase in the absolute enthalpy value during crystallization and melting were observed for the encap-C20/EC/MC microparticles with a 9% (w/w) EC/MC polymer content. The mechanism that leads to the increased latent heat storage capacity is discussed. The blending of the water-dispersible C20-loaded EC/MC microspheres into natural rubber latex showed excellent compatibility, and the obtained rubber composite showed not only an obvious thermoregulation property but also an improved mechanical property.