จำนวน Repository ( 8 )
Efficiency of reducing mixing energy and mechanical properties of rubber vulcanizatesfrom natural rubber with silica masterbatch
The natural rubber with silica masterbatch was produced and used as based material in rubber compound modified from standard tread formulation given in ASTM E 1136. The reduction of mixing energy and rubber vulcanizate properties were investigated. Results indicate that in comparison with STR 5L compound the rubber with silica masterbatch i.e. fresh latex (FNRmSi) low viscosity natural rubber used 1.0 phr of hydrogen peroxide (LNR1mSi) and low viscosity natural rubber used 0.34 phr of hydrogen peroxide and 2.7 phr of potassium persulphate mixture (LNR2mSi) provides maximum mixing energy saving of 30.48% 33.37% and 37.20% respectively. The scorch time and cure time rise with increasing filler loading. The mechanical properties of LNR1mSi and LNR2mSi are similar to those STR5L compound whereas FNRmSi vulcanizate shows superior mechanical properties such as 300% modulus tear resistance abrasion resistance elongation at break and tensile strength. The homogenous distribution and interfacial interaction of silica filler and natural rubber matrix were enhanced by the self-assembled silica masterbatch as shown by the fracture surfaces morphology of the vulcanizate using a Scanning Electron Microscope (SEM). The silica masterbatch form has reduced the mixing power consumption and enhanced the mechanical properties.
Mechanical Properties of Silica-Based Geopolymer Composites Cured at Ambient Conditions in Accordance with Size-Independent Method
In this paper silica-based geopolymer matrix reinforced composites containing approximately 35 50 or 55 wt.% of carbon (HTS 5631 1600tex 24K TohoTenax) advanced basalt (BCF13-2520tex KV12 Int Basaltex) or electrical grade glass (E-glass: E2400P192 Saint-Gobain Vetrotex) roving fibers respectively were synthesized and fabricated at ambient conditions. The flexural properties of the resulting composites which are high toughness: the shear stress plays here a greater role in compared with other ceramic matrix composites were determined on a universal testing machine under three-point bending mode in accordance with novel size-independent method which based on testing specimens at different scale of sample height (H) to span length (L) ratios; The basic principles of the new size-independent approach are presented as well. Microstructures of composites were analyzed by means of scanning electron microscope (SEM) on perpendicular sections the images show the adhesion between the fibers and geopolymer matrix are very good and micro-cracks on both cross-sections and surfaces of geocomposites are determined as inborn defects of inorganic matrix composites.
Phosphonic Acid Functionalization of Hyperbranched Polyamidoamine Grafted Ultrafine Silica to Prepare the Flame Retardant for Cotton Fabric
Grafting of hyperbranched polyamidoamine (PAMAM) dendrimer onto ultrafine silica followed by the introduction of phosphonic acid groups onto branch ends was carried out. First an initiating site was incorporated into silica surface by reacting the silica silanol group with 3-aminopropyltriethoxysilane producing amino-functionalized silica. The free amine group content was controlled by varying ratios of methanol to water in the hydrolysis step of sol-gel reaction. Then grafting of PAMAM was performed by repetitive reactions between Michael addition of silica amino groups to methyl acrylate and amidation of the resulting terminal methyl ester groups with ethylenediamine. Amino group content in each generation was determined. This was found to be significantly lower than theoretical value due to unavoidable side reactions. After the G3.0 hyperbranched PAMAM grafted onto silica was synthesized phosphonic acids functionalization of the terminal amino groups by the Mannich type reaction was carried out. The phosphorylated hyperbranched PAMAM grafted silica was achieved and its application on cotton fabric to produce phosphonated cellulose was studied.