Is bonded rubber a chemically bonded polymer?

An autoclave approach for measuring bound rubber was developed by Hoshikawa et al. [27, 28], and this toluene extraction was conducted on CB-filled SBR samples for 24 h at 150 °C with a pressure of about 300 kPa. The tightly bound polymer assessed from this measurement protocol was considered to be chemically bonded to the filler.

Is the polymer layer in Rubber Co-mingled and entangled with unbound polymer?

This implies that the total bound polymer layer in the filled rubber – which is composed of the physically and chemically bound chains described above – is co-mingled and entangled with a significant amount of unbound polymer (see visual illustration of relative chain density near the CB surfaces in Fig. 1 a compared to Fig. 1 b).

What is a polymer (rubber) chain?

A polymer (rubber) chain is divided into bound rubber chains, interfacial chains that are in close proximity but not bound with filler, and free mobile chains that locate apart from filler. Source: Moldovan et al. .

What role does bound rubber play in a polymer matrix?

The key role in this process is ascribed to bound rubber (BR) that engages with the matrix as well as with adjacent nanofillers. To date, this understanding has been impeded by the lack of experimental tools to directly probe the BR chains buried in a polymer matrix composed of the same polymer.

How small is chemical bound rubber?

The chemical bound rubber from our three-step extraction procedure appears to be quite small at less than 1% of the total SBR (β = 0.86%), but this translates into 31 polymer chains that are chemically attached to each carbon black aggregate which seems significant.

What is bound rubber elastomer?

Bound rubber is the elastomer insoluble in solvents due to chemisorption onto the carbon black during mixing. It is extracted by swelling the unvulcanized polymer in a solvent for an extended period. Any soluble lower molecular weight polymer that is not bound to the carbon black is removed.