Patent
(page 2)

Under the heading, "Future trends in manufacture" the author further states, "So long as high temperatures are necessary for fibre destruction, extensive chain scission must take place and result in a product consisting essentially of fragmentary molecules. Under these conditions there appears to be little prospect of any very pronounced improvement in reclaim qualities. Already it is evident that the employment of the digester process for SBR and other types of synthetic is introducing complications due to heat hardening..."

Chart #2 would seem to support this theory. For example, Nitrile rubber has an ignition temperature (or char temperature) of 700 F and EPDM has an ignition or char temperature of 730 F. The oils used in either compound will flash off at 540 F. Thus in either case, the "safe temperature" would be well under 540 F.
In the patent application for TRC, we are using superheated steam at temperatures up to 800 F for short periods of time, without the use of any chemicals or oils. Furthermore, the TRC finished reclaim does not require further processing through cracker or refiner mills, as the author of the attached article states is required in every case.

In the second preceding paragraph, the author states that high heat causes extensive chain scission. We submitted samples of a polymer (EPDM) devulcanized and the original formula to an outside A2LA accredited lab (Akron Rubber Development Lab) for testing. Their testing proved that the molecular backbone of the polymer was untouched and only the cross-linked sites were broken. They further stated that this was the first time they had ever witnessed a devulcanized product where there was no indication that the polymer had been devulcanized. (No traces of outside chemicals and no breakdown of the polymer backbone)

Chapter IV, Part One, `FUNDAMENNTAL ASPECTS OF RECLAIMED RUBBER", by the same authors states on page 254 "The high state of cure obtained by modern vulcanization techniques and the use of antioxidants, together with those reinforcing pigments which induce strong forces, have greatly increased resistance to thermal plasticisation, as well as necessitating a more intense degree of subsequent mechanical working. He goes on to state, "The "devulcanisation" reaction is stated to be doubled for each rise of 5.5 C, but heat alone is not adequate for plasticisation (Italics added) and techniques using swelling agents, plasticisers, reclaiming agents and sometimes the deliberate addition of oxygen have been developed.

Again, we have the author stating that the heat resistance of the rubber requires the use of chemicals and more intense mechanical work to "reclaim" the rubber and furthermore, heat alone is not adequate. On page 257, the authors state, "Modern theories regard the presence of a least traces of oxygen as essential for the breakdown of olefin polymers, and reclaimers have long known that the presence of air facilitates the thermal plasticisation of vulcanised rubber".
The key to our patent application is the fact that the TRC process does not require swelling agents, reclaim oils, peptizers or further mechanical breakdown. Against popular opinion, developed since 1858 and running up to present day, we are able to break down the cross link sights by superheated steam, in the absence of oxygen.

On page 261 they refer to the dramatic drop (66%) in tensile strength of a tire tread compound, with a resultant drop of almost 40% in elongation. The TRC process proves there was only a 13% maximum drop of tensile strength in a compound containing 60% reclaim and a maximum drop of 9% in elongation for the same compound. (See Chart )

The authors state on page 260, "On the other hand, it is thought that the breaking up of the network structure by either direct or indirect rupture of linkages is perhaps a rather idealised concept, (emphasis added) more especially in the light of the possible modifications of the cross-link....".

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