Effect of Oleic Acid on Properties of Natural Rubber Filled Bacterial Cellulose

Natural rubber (NR) containing the nata de coco fiber or Bacterial cellulose (BC) was prepared by co-coagulation of BC and concentrated NR latex with CaCl2 and compounded by two roll mill. The effect of oleic acid (OA) containing in NR filled BC (NR/BC) was the important factor in this study. BC was varied from 0–25 parts per hundred parts of rubber (phr), and the Mooney viscosity, cure characteristics and mechanical properties of NR/BC with and without OA as compatiblizer was evaluated. It was found that tear strength and elongation at break of NR/BC containing OA improved. The addition of OA into NR/BC affect vulcanization properties of NR/BC masterbatch that retard the cure time of their compound. Of all BC contents investigated, the vulcanized NR/BC at 10-20 phr of BC with OA shows the optimum tear strength and the morphology of the vulcanized NR/BC is improved by the addition of OA.</jats:p

Antibacterial Activity of TiO&lt;sub&gt;2&lt;/sub&gt; and Fe&lt;sup&gt;3+&lt;/sup&gt; Doped TiO&lt;sub&gt;2&lt;/sub&gt; Nanoparticles Synthesized at Low Temperature

Nanocrystalline TiO2 powder with and without Fe3+ doping were successfully synthesized at low temperature by a microwave-assisted sol–gel method. The synthesized TiO2 powders were characterized by XRD, BET, FT-IR and SEM. It was found that anatase phase was formed after refluxed at 80°C using a domestic microwave oven. Antibacterial behavior towards E. coli was then studied under UV and fluorescent irradiation. The synthesized pure TiO2 powder exhibited superior antibacterial activity under fluorescent irradiation compared to the commercial TiO2 (Degussa P25). It can efficiently destroy E. coli bacteria after 20 min with UV irradiation and 3 h with fluorescent light; this good activity is mainly related to the high OH radicals on its surface. It was also observed that the synthesized powders have smaller crystallite size and larger specific surface area than those of Degussa P25 due to the absence of high temperature calcination requirement.</jats:p

Compatibilization Efficiency of Polybutadiene-Grafted Maleic Anhydride in Ethylene-Propylene Diene Rubber/Epoxidized Natural Rubber Blends

This research aims to investigate the efficiency of polybutadiene-grafted maleic anhydride (PB-g-MAH) as the compatibilizer for ethylene-propylene diene rubber and epoxidized natural rubber (EPDM/ENR) blends. PB-g-MAH was varied from 0-10 parts per hundred parts of rubber (phr), and the cure characteristics, mechanical and dynamic properties of 70/30 EPDM/ENR blends with and without compatibilizer were evaluated. It was found that the minimum torque, maximum torque, scorch and cure times of the blends increased after adding PB-g-MAH, whereas cure rate decreased. The morphology of the blend is improved by the addition of PB-g-MAH in small amounts, owing to an improved compatibility of these rubbers confirmed by dynamic mechanical property. The hardness and oil resistance increased with increasing PB-g-MAH content. Of all blends investigated, the blend compatibilized with 2-4 phr of PB-g-MAH shows the optimum mechanical properties and thermal resistance.</jats:p

Effect of Natural Rubber Contents on Biodegradation and Water Absorption of Interpenetrating Polymer Network (IPN) Hydrogel from Natural Rubber and Cassava Starch

AbstractInterpenetrating polymer network (IPN) hydrogel based on crosslinked natural rubber (NR) latex and crosslink cassava starch (St) was successfully prepared by a solution blending technique. Crosslinked NR latex was firstly prepared in emulsion state at 70°C by using potassium persulfate as initiator and N, N’-methylene-bis-acrylamide (MBA) as crosslinker. Secondly, the crosslinked NR latex was mixed then with gelatinized cassava starch and maleic acid (MA) as crosslinker for starch at ambient temperature by using mechanical stirrer. Finally, the mixture was casted on a glass mould to form IPN NR/St sheet via crosslinked reaction at 120 oC in oven for 1.5h. The water absorption, tensile properties, gel and soluble fraction in water as well as biodegradation of IPN NR/St hydrogels were investigated. It was found that water absorption, soluble fraction, biodegradation and tensile properties decreased with increasing NR contents, while gel fraction in water and elongation at break increased. This was because the rubber molecules prevented the hydrogel from dissolution in water and degraded by microorganism. Furthermore, by immersion of IPN NR/St for long time, water absorption of hydrogel increased with increasing rubber contents due to the effect of elasticity of rubber molecule to easy expansion of INP NR/St hydrogel

Titanium Dioxide Thin Films Deposited by Electric Field-Assisted CVD: Effect on Antimicrobial and Photocatalytic Properties**

Thin films of anatase titanium dioxide are deposited on fluorine-doped tin oxide (FTO) glass substrates utilizing the electric field-assisted aerosol (EA)CVD reaction of titanium isopropoxide in toluene at 450 °C. The as-deposited films are characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (RS), and UV-vis spectroscopy. The photoactivity and antibacterial activity of the films are also assessed. The characterization analysis reveals that the use of an electric field affects the film microstructure, its preferential orientation, and the functional properties. XRD of the anatase films reveals that the application of electric fields causes a change in the preferential orientation of the films from (101) to (004) or (211) planes, depending on the strength of the applied field during the deposition

Immunodominance of LipL3293–272 peptides revealed by leptospirosis sera and therapeutic monoclonal antibodies

Background/Purpose: Leptospirosis is a neglected zoonosis, imposing significant human and veterinary public health burdens. In this study, recombinant LipL3293–147 and LipL32148–184 middle domain of LipL3293–184, and LipL32171–214, and LipL32215–272 of c-terminal LipL32171–272 truncations were defined for immunodominance of the molecule during Leptospira infections revealed by leptospirosis sera. Results: IgM-dominant was directed to highly surface accessible LipL32148–184 and Lipl32171–214. IgG dominance of LipL32148–184 revealed by rabbit anti-Leptospira sera and convalescent leptospirosis paired sera were mapped to highly accessible surface of middle LipL32148–184 truncation whereas two LipL32148–184 and LipL32215–272 truncations were IgG-dominant when revealed by single leptospirosis sera. The IgM-dominant of LipL32148–214 and IgG-dominant LipL32148–184 peptides have highly conserved amino acids of 70% identity among pathogenic and intermediate Leptospira species and were mapped to the highly surface accessible area of LipL32 molecule that mediated interaction of host components. IgG dominance of two therapeutic epitopes located at LipL32243–253 and LipL32122–130 of mAbLPF1 and mAbLPF2, respectively has been shown less IgG-dominant (<30%), located outside IgG-dominant regions characterized by leptospirosis paired sera. Conclusion: The IgM- and IgG-dominant LipL32 could be further perspectives for immunodominant LipL32-based serodiagnosis and LipL32 epitope-based vaccine. Keywords: Leptospira spp., LipL32, IgM-dominant LipL32 peptide, IgG-dominant LipL32 peptide, Therapeutic LipL32 epitope