Recycling and application of wasted polytetrafluoroethylene via high-energy ball milling technology for nitrile rubber composites preparation

Abstract

Wasted polytetrafluoroethylene fibers were recycled using high-energy ball milling technique, and the recylced polytetrafluoroethylene (r-PTFE) was employed to prepare nitrile rubber (NBR)/r-PTFE composites. The structure of r-PTFE and properties of NBR/r-PTFE composites were investigated by polarized optical microscope, laser particle size analyzer, differential scanning calorimetry, and scanning electron microscopy, respectively. The results show that increasing the milling time from 4 to 7 h leads to decreasing the average particle size, the degree of crystallinity and the number-average molecular weight of r-PTFE, whereas no obvious change is found by further prolonging the milling time. It is also clear that the NBR/r-PTFE composite with the r-PTFE obtained from a longer milling time possesses a higher mechanical and solvent resistance property. Compared with pure NBR, NBR/r-PTFE composites with r-PTFE for 7 h milling show a 21.9% increase in modulus at 300% and 27.8% decrease in swelling index. POLYM. ENG. SCI., 56:643-649, 2016.

Wear-Resistant Elastomeric Composites Based on Unvulcanized Rubber Compound and Recycled Polytetrafluoroethylene

“…The presence of such functional groups and persistent reactive radicals improves the compatibility and uniform distribution of recycled PTFE in the URC/PhFR matrix. Other studies [26,37] indicate that the stimulation of intramolecular stress relaxation occurs under the influence of ionizing radiation, alternating mechanical and temperature loads. In addition, in correspondence with a decrease in polarization in PTFE particles and the transition of particles to an unpolarized equilibrium, an uncharged state takes place.…”

“…Special compounding processes have been developed to reduce the fibrillation effect and facilitate the dispersion of high-molecular-weight PTFE in elastomers. Methods for the surface modification of PTFE powder to improve compatibility with hydrocarbon elastomers and reduce agglomeration have also been reported [22,[24][25][26]. It is known that high-energy gamma radiation and electron beam radiation affect the physical and mechanical properties of PTFE [27][28][29][30].…”

“…For instance, radiation-treated PTFE exhibits a better reinforcing effect than non-irradiated PTFE in polar systems [23]. Khan et al [24,25] and Cao et al [26] report that high-energy irradiation reduces the energy required to produce PTFE powder from its waste and results in a powder that does not agglomerate. Portnyagina et al [31] show that the introduction of ultrafine polytetrafluoroethylene into propylene oxide rubber leads to a decrease in the coefficient of friction and an improvement in the wear resistance of the material by 21%.…”