Nanoscale additives, glass transition

The curing and dynamic properties of precipitated nano-silica on NR without and with the sulfur addition (NR with S), synthetic polyisoprene (IR), polybutadiene (BR) and SBR was investigated. Silica was treated with bis(3-triethoxysilylpropyl)tetrasulfane (TESPT) to form bonds at interfaces. Cure, Mooney viscosity, glass transition temperature, bound rubber, crosslink density and DMA were measured. The properties of silica-filled SBR and BR correlated with highest rolling resistance and SBR-silica correlated with best skid resistance. A Payne effect was observed in the loss modulus under some experimental conditions. In addition to possible filler de-agglomeration and network disruption, the nanoscale of the filler may have further contributed to the non-linear response typified by the Payne effect. ... 

Paul and Robeson et al. [139] have published an extremely informative review on the properties of exfoliated nanoclay-based nanocomposites. These have dominated the polymer literature, but there are a large number of other significant areas of current and emerging interest. This review details the technology involved with exfoliated clay-based nanocomposites and also includes other important areas, such as barrier properties, flammability resistance, biomedical applications, electrical/electronic/optoelectronic applications, and fuel cell interests. The important question of the nanoeffect of nanoparticles or fiber inclusion relative to their large-scale counterparts is addressed relative to crystallization and glass transition behavior. Other polymer (and composite)-based properties derive benefits from the nanoscale filler or fiber addition, and fhese questions are addressed. 

In addition to chemical structure, the polymer crystallinity, crystal structures, molecular orientation, melting temperature (2A), glass transition temperature (Tg), cross-linking density, external particulates present in the polymer network, and micro- and nanoscale structure of the scaifold also influence the degradation rate. ... 

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