Fillers nano, surface modification

The properties of rubber-rubber blend composites depend on the size and shape and concentration of nano particles and their interactions with the individual mbber matrix. The interaction between the filler and the matrix are improved by surface modification. In the mbber industry the uniform distribution of nano particles is considered to be important as it affects the mechanical properties and performance of the composite. For mbber-mbber blend composites fillers like carbon black prefer to migrate to less polar, less viscous mbber phase whereas silica and clay particles migrate to more polar mbber phase. CNTs mainly reside in the highly polar and non-polar mbbers but not in weakly polar ones. The Tg remain unaltered for a completely incompatible blend. In the case of partially compatible blends, the Tgs of the blend components are expected to shift towards each other as compared with the pure components. Shifting of Tg of polymers to lower or higher values in a blend depends on the polarity difference and the difference in the thermal expansion coefficient of the respective polymers in the blend. 

Filler surface modification and nanocomposite fabrication. Agglomeration of nano-CaC03 in the surface modification process has remained a major problem because of the enormous interfacial area of the nanoparticles. The uniform dispersion of nano-CaCOs in polymer precursors and melts, therefore, still presents a key challenge for the in-situ polymerization and melt compounding approaches. Carefully engineering and fiill understanding of interfacial properties are needed, and ultimately many perspectives will develop, dictated by the final applications of each specific system. 

Other filler materials are hydroxyapatite, aluminum oxide and aluminum nitride. In addition, nanofillers are used. PEEK polymer filled with nano sized silica or alumina fillers of 15-30 nm exhibit an improvement of the mechanical properties by 20-50%. The agglomeration tendency can be somewhat dimiiushed by a modification of the surface of the fillers with stearic acid. °... 

In this chapter, the study carried out on nanofillers reinforced natural/synthetic rubber has been discussed. After a description on the NR rubber and CaCOs as filler, the development of synthetic composites with the incorporation of micro and nano-CaC03 as a filler material has also been discussed for comparative study. In particular, the role of fillers on the property modification of rubber properties, such as surface properties, mechanical strength, thermal conductivity, and permittivity has been mentioned. The effectiveness of this coating was demonstrated. The importance of well-dispersed nanoparticles on the improvement of the mechanical and electrical properties of polymers is also emphasized. However, one of the problems encountered is that the nanoparticles agglomerate easily because of their high surface energy. 

Polymer/CaCOs nanocomposites have developed rapidly in the past few years. Cubic nano-CaCOs particles with narrow size distribution can now be produced on a massive scale at relatively low cost. Nanometer-scale dispersion of CaC03 particles in common polymer matrices has been successfully achieved via in-situ polymerization and/or melt-compounding with the aid of organic modification of filler surface. The nanocomposites fabricated possess a combination of good mechanical properties, processability and improved temperature resistance at... 

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