Solution Cross-Linked Natural Rubber (NR)/Clay Aerogel Composites

Abstract

Aerogels are structural materials with ultralow bulk densities (often less than 0.1 g cm -3 ), which stand out as good candidates for a variety of applications. In the present study, natural rubber (NR)/ clay aerogel composites were produced by freeze-drying of the aqueous aerogel precursor suspensions, followed by solution cross-linking of the aerogel samples in benzene using sulfur monochloride (S 2 Cl 2 ) as a cross-linking agent. The influences of cross-linking conditions, i.e., cross-linker concentration and reaction temperature, as well as polymer loading on the aerogel structure and properties were investigated. 1% (v/v) of S 2 Cl 2 and reaction temperature of -18°C were found to be the optimum conditions for producing a strong and tough rubber composite; the 2.5 wt % NR aerogel, for example, after being cross-linked, exhibited a compressive modulus of 1.8 MPa, 26 times higher than that of the neat control. These favorable mechanical properties are attributed to the high local concentration of rubber and S 2 Cl 2 in the freeze-dried structures, giving rise to the high cross-linking efficiency. Increasing the rubber concentration led to a substantial increase in the mechanical strength, in accord with the changes in microstructure and degree of cross-linking. The swelling capacity of the NR aerogels decreased with either increasing the cross-linker concentration or decreasing the weight fraction of rubber. Cross-linking of the rubber aerogels brought about increased thermal stability, consistent with restricted thermal motion of NR chains.

Development of facture free clay-based aerogel: Formulation and architectural mechanisms

“…Raising the polymer content inevitably leads to the increase of density and decrease of pore size, which are both unfavourable to thermal insulation. While it is hard to make balance between thermal insulation and mechanical strength through this approach, some researchers try to strengthen the aerogel by primary cross-linking in wet state before freezing and then conduct secondary curing after freezing-dry [27]. This may incur complicated procedure and unwanted chemical reaction.…”

A Facile Pathway to Modify Cellulose Composite Film by Reducing Wettability and Improving Barrier towards Moisture

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Bifunctional Regenerated Cellulose Membrane Containing TiO2 Nanoparticles for Absorption and Photocatalytic Decomposition

“…Meanwhile, the pore volumes (V p ) of the samples were calculated through the water uptake of the membranes. Since water did not dissolve cellulose and TiO 2 , therefore value of V p can be determined from (7) (Pojanavaraphan et al 2011…”