Silica tensile properties

Finer dispersion of silica improves the mechanical and dynamic mechanical properties of the resultant composites. Figure 3.11a and b compares the tensile properties of the acrylic copolymer and terpolymers in the uncross-hnked and cross-linked states, respectively. 

In all of the rheometer testing of the uncured compounds, the commercial silica AZ showed the highest values with the B1 and B3 samples having the highest values among the B-series silica samples. The Mooney viscosity at 100°C increases as the number of particles in the aggregates increases. The same compounds were cured and tested, measuring tensile properties, tear resistance. 

The effect of the microstructure of acrylic copolymer/terpolymer on the properties of silica-based nanocomposites prepared by the sol-gel technique using TEOS has been further studied by Patel et al. [144]. The composites demonstrate superior tensile strength and tensile modulus with increasing proportion of TEOS up to a certain level. At a particular TEOS concentration, the tensile properties improve with increasing hydrophilicity of the polymer matrix and acrylic acid modification. 

Most conspicuous is the steep tensile curve for the S-SBR sample containing PTh-silica. The PTh-silica gives the best improvement in tensile properties in terms of tensile strength, modulus at 100%, and modulus at 300%, but elongation at break is lower. The PA- and PPy-silicas as well as the silane-treated silica result in only a slight... 

Overall, the plasma-treated samples show an improvement in terms of dispersion and tensile properties. Treatment with different plasma monomers show different levels of improvement in terms of dispersion and final vulcanizate properties due to the different levels of compatibilization in the polymer blend and, more specifically, with the different polymers used in this blend. The most important aspect for achieving an optimal balance between the properties of a filled polymer blend for a specific application is the selection of the proper monomer for the plasma modification of the silica surface, in relation to its required compatibility with a particular polymer in the blend. 

White (silica) fillers, often surface treated, are sometimes used to improve flow, moisture resistance, and tensile properties.25 27... 

The use of inert materials in vinyls is widely practiced. The filler can be used to lower cost and increase hardness. The most common types of fillers in use today include the calcium carbonates and silicate types. Also available are various silica gels, barytes, gypsum, alums, wood flour, and antimony oxide. Depending upon the oil absorption value of the inert material, a filler will (1) lower tensile properties, (2) increase hardness, (3) lower flexibility, and (A) increase processing temperatures. 

Effect of silica on tensile properties of films cast from silicone latexes. The curve marked 0 pph was obtained from a film containing 2 pph of sodium silicate instead of collodal silica (pph = parts per hundred). 

In another study, the ground reclaim rubber was blended with stirene-butadiene rubber and cured under pressure at 160°C. The cured sheets were silica-reinforced by soaking in tetraethyl ortho silicate, then in an aqueous solution of n-butyl amine catalyst, followed by heat treatment at 50°C. The tensile properties of the blends containing conventionally incorporated silica, with no coupling agent, were superior to those containing silica incorporated by the sol-gel reaction [21]. 

Fillers increase the strength, impart needed rheological properties, and reduce the cost of sealants. Tensile properties are increased significantly, depending on the type of filler, its particle size, and the type of cure. Improper filler selection can ruin the performance of a polysulfide sealant. Calcium carbonates (wet or dry ground limestone, precipitated), carbon blacks (furnace, thermal), calcined clays, silica and silicate fillers, and rutile titanium dioxide are typical fillers used in polysulfide sealants. Generally, combinations of fillers are used in formulation. Plasticizers improve the working properties while... 

Crespo et prepared NR nanocomposites with OC as a substitute for silica by conventional mechanical mixing. The results revealed that the OC was homogeneously dispersed in the NR matrix. The mechanical properties of NR indicated that 50 phr of silica can be replaced by 4 phr of OC without adversely affecting the tensile properties of the final material, even after ageing. 

Silica reinforcement using the sol gel technique on epoxidized natural rubber 25 mol% (ENR 25) has been reported. ENR was first pre-ciued with 3-aminopropyltriethoxysilane (APS). APS was mixed into ENR and the ENR-APS mixture was cured at 180 °C to produce pre-ciued rubber sheets with tensile properties much lower than those of normally ciued rubber vulcanizates. The crosslinking of ENR utilizing the epoxy groups as crosslinking sites using amine functional groups catalysed by bisphenol A has been established. The ENR-APS network is shown in Scheme 7.2. 

This method allows the sol-gel siliea NR latex eompound to be moulded into the desired shape. TESPT was eo-mixed with TEOS and eoneentrated NR latex. Ammonia which functioned as base catalyst was added into the concentrated NR latex. The silica-TESPT-NR latex compound was then subjected to heat to complete the sol-gel silica conversion process. The dried sol-gel silica-NR mixture was compounded as per normal mixing procedure. A good dispersion of silica particles of the size between 100 and 500 nm was achieved. Using the two-level factorial design, it was concluded that the mechanical properties, i.e. tensile properties and tear strength, were significantly affected by the TEOS loading. It was also found that the amount of ammonia present in the concentrated latex, i.e. 0.7% (w/w) was sufficient to convert TEOS into silica. 

Effects of silica modifled by radiation- and thermal-induced admicellar polymerization on the mechanical properties i.e. tensile properties and tear strength of the reinforced polyisoprene were compared with those of the typical silica filled polyisoprene with and without TESPT. "... 

The filled composites containing 5 phr of nano-ZOS and 10-15 phr of SCC exhibited comparable tensile properties, tear strength and hardness as that of the microcomposite containing 5 phr of micro-ZnO and 30 phr of precipitated silica. These observations also support the findings that stearic acid-coated nano-ZnO (ZOS), nano-BIAT and SCC are better dispersed due to the small size of the particles as well as the higher specific surface area as already discussed in this chapter. 

The various properties of the silica filled compounds were improved compared to the unfilled compounds. The torque values of the filled compounds were increased due to the increase in viscosity. The scorch time and optimum cure time significantly decreased due to the heat conduction of filler particles. Tear and tensile properties of the silica filled compounds were considerably higher because of the effects of strain amplification and hysteresis of the silica filled vulcanizates. ... 

Properties of Silicone Rubbers. Gum vulcanizates have essentially no tensile strength. Fillers are therefore essential. Reinforcing silicas are frequently used. Even then, the tensile properties and abrasion resistance of silicone rubber vulcanizates are poor in comparison with of other types of elastomer. However, the properties change very little with increasing temperatures. These polymers excel in high-temperature applications. 

In many cases several different fillers are used in a composite material. The use of a clay with fiber glass is one typical combination. The clay is used to add bulk and improve primarily the compression properties while the fiber glass is used to improve the tensile and compression properties. The relatively inert extender also reduces the coefficient of thermal expansion and improves the thermal conductivity which is advantageous in many cases. Colloidal silica is also frequently added to glass reinforced materials to improve the tensile properties by stiffening the resin phase. Beryllium fillers greatly increase the thermal conductivity. 

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