A Novel Method to Recycle Scrap Tires: High-Pressure High-Temperature Sintering

Abstract

High-pressure high-temperature sintering (HPHTS) is a novel recycling technique that makes it possible to recycle vulcanized rubber powders made from waste rubber (namely scrap tires) through only the application of heat and pressure. A brief look into the mechanism of sintering will be presented along with information about the influence of molding variables, such as time, temperature, pressure and rubber particle size on the mechanical properties of the produced parts. One of the most interesting observations is that powders of every crosslinked elastomer attempted sintered together via this technique, including silicone rubber (SI), sulfur cured [natural rubber (NR), ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR)], peroxide cured butadiene rubber (BR), and fluoroelastomers (FKM). Early work on sintered rubber made from commercially available rubber powder had a modulus of 1 to 2 MPa, strength of 4 to 7 MPa and an elongation at break of 150–250%. Recently, in-house ground samples of SBR have had sintered values over 9.5 MPa strength and 275% elongation, or greater than 60% retention of the original properties. Many of these mechanical properties are comparable with industrially manufactured rubbers, and it is believed that recycled rubbers produced via HPHTS offer the potential to replace virgin rubber in numerous applications.

Rheological properties of a reclaimed waste tire rubber through high-pressure high-temperature sintering

“…The crumb rubber may consist of mixing between synthetic (SBR, EPDM) and natural rubber (Isoprene). The samples are prepared by coined method HPHTS [9,10] using custom made hydraulic hot press with temperature controlled heating. Sintered specimens of the recycled rubber powders are obtained by placing approximately 2 g of powder into a 30 mm diameter mold for an hour, applied pressure of 25 MPa and heating temperature of 200 C. During sample preparation, the starting temperature is about 27 C transiently increasing until 200 C for 17-20 minutes.…”

“…Reclaiming waste tires were usually performed by blending WTR with virgin rubber or by revulcanizing the dead rubber by treating it in physical and/or chemical ways. Morin et al [9] and Tripathy et al [10] proposed HPHT sintering to reclaim tire rubber based on supporting research by Tobolsky and coworkers [11][12][13][14]. Departing from fundamental theory of rubber scission and reformation, Morin et al [9] discovered that HPHT successfully reclaims WTR without the incorporation of virgin rubber.…”

“…High Pressure High Temperature (HPHT) sintering proposed by Morrin et al [9] was successfully reclaiming waste rubber without incorporation of virgin rubber. The working principle of HPHTS method is simultaneous compaction under high pressure (about 14-25 MPa) and high temperature (180 -200 C).…”

“…Dynamic properties of rubbery material is an important thing since the application of rubber lies in dynamic condition. Therefore, this study intends to reveal the dynamic properties of reclaimed waste rubber through HPHTS coined technique introduced by Morrin et al [9].The dynamic properties of reclaimed rubber are obtained through the rheological test as the focus of this article.…”

Physicochemical Properties and Stress-Strain Compression Behaviors of a Waste based Magnetorheological Elastomers

“…The previous investigation on the use of hundred percent purely recycled rubbers to produce new components is very limited [22][23][24][25]. Consequently, the resulted product from rubber waste reclamation does not have high economic value and has limited functional uses.…”