US 2012/0238694 A1Published application

Powdered metastable polymer material

AssigneeMercurhone

InventorBeom-Jun Yi

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Abstract

The novel group of polymers is presented under the name of Powdered Metastable Polymer Material (PMPM). PMPM is in a chemically stable state at an ambient temperature of 25° C. for a relatively long time, but it is in a thermodynamically unstable state, and may change to either a stable state (in this case, re-vulcanization), or an unstable state (in this case, decomposition). According to the prior art, these PMPMs are, under various conditions, reactive, malleable, processable, compoundable, re-vulcanizable and re-polymerizable, and thus makes it possible to form new vulcanized or coagulated products, with or without moulds, with or without other polymers or elastomers, cross-linking agents, compatibilizers, various additives, etc. PMPM is manufactured by a process known as metactivation, which applies to pre-vulcanized, polymer granules, a multi-directional microcracking by individual rotary compression and a disintegration by micro auto-explosion, thus obtaining a metastable state by virtue of activation enthalpy reduction, necessary for triggering a spontaneous reaction. The classification of recycled rubbers in the forms of granules or powders, manufactured from pre-vulcanized rubbers is arranged in a table that classifies the typologies according to their scientific characteristics, which makes it possible to demonstrate the specificities of the PMPM. The properties of this group, which are fundamentally novel, open the way to the complete reuse (material recycling) of pre-vulcanized polymers, such as used tires.

The material(s) which is comprised of polymer particles smaller than 3 millimeters (mm) in diameter, whereof the mass is a polymer compound mixed with diverse chemical substances used in the polymer industry, such as fillers (e.g. carbon black), vulcanizing agents (e.g. sulphur), peptizing oils (e.g. aromatic oil), activators (e.g. zinc oxide), accelerators, antioxidants, etc. This polymer material in particles is produced solely through a mechanical process , from pre-vulcanized gum granules (initial material), generally ranging in size from 1 to 5 mm, coming from used rubber products/items (e.g. used tires), rubber product wastes, rubber factory scraps, etc. The aforementioned polymer material(s) in particles does present the following characteristics:

Shape:
the surface of the material particles shows a particular shape with micro-grains of 1 to 20 microns, more or less spherical, similar to the grains inside a pomegranate.
Size (mm):
measured by granulometry after sieving, the size in diameter of the material particles, identified at the peak position of the Gaussian curve, is on average 2 to 15 times smaller than that of the initial material particles, i.e. pre-vulcanized gum granules.
Bulk density (g/cm3):
measured by tapping, the bulk density is on average, 5 to 20% smaller than the initial material, i.e. pre-vulcanized gum granules.
Specific surface (cm2/g):
measured by the BET method with Krypton, the specific surface is on average 5 to 20 times higher than that of the initial material, i.e. pre-vulcanized gum granules.
Specific heat (J/° C.g):
measured by the DSC/MDSC method, the specific heat is on average 5 to 20% higher than that of the initial material, i.e. pre-vulcanized gum granules.
Devulcanization rate (%):
measured by the Swelling technique of Gel fraction according to the Soxhlet method and the Flory-Rehner equation, the devulcanization rate is more than 20%, but varies between 20 and 90%, depending on the initial material, i.e. pre-vulcanized gum granules.
Depolymerization (or, degradation) rate (%):
measured by Gel fraction using the Soxhlet method, the depolymerization rate is less than 30%, but is variable between 3% and 30%, depending on the initial material, i.e. pre-vulcanized gum granules.

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Abstract

Claims6