The disposal of used automobile tires is a major waste concern. Simply stacking tires and allowing them to decompose will harbor breeding mosquitoes that spread viruses, whereas burning them will release acidic and toxic gases. Therefore, one viable option is pyrolysis, where elevated temperatures are used to facilitate the decomposition of a material. However, the lack of theoretical support for pyrolysis technology limits the development of the pyrolysis industry when it comes to discarded tires. The purpose of this research is to put forward a brand-new multi-kinetic research method for studying materials with complex components through the discussion of various kinetic research methods. The characteristic of this kinetic research method is that it is a relatively complete theoretical system and can accurately calculate the three kinetic factors considered during the pyrolysis of multicomponent materials. The results show that the multi-kinetic research method can obtain the kinetic equation and reaction mechanism for the pyrolysis of tires with high accuracy. The pyrolysis process of this compound was divided into two stages, Reaction I and II, where the kinetic equation of Reaction I was $f\left(\mathsf{\alpha }\right)=0.2473{\mathsf{\alpha }}^{-3.0473}$ , with an activation energy of 155.26 kJ/mol and a pre-exponential factor of 5.88 × 10⁹/min. Meanwhile, the kinetic equation of Reaction II was $f\left(\mathsf{\alpha }\right)=0.4142\left(1-\mathsf{\alpha }\right){[-\ln \left(1-\mathsf{\alpha }\right)]}^{-1.4143}$ , while its activation energy was 315.40 kJ/mol and its pre-exponential factor was 7.86 × 10¹⁷/min. Furthermore, based on the results of the research analysis, the reaction principles corresponding to Reaction I and Reaction II in the pyrolysis process of this compound were established.

In this study, the two key factors affecting the thermal performance of the insert rubber and stress distribution on the tire sidewall were analyzed extensively through various performance tests and simulations to promote the development of run-flat tires. Four compounds and two structures of insert rubber were designed to investigate the effects of heat accumulation and stress distribution on durability testing at zero pressure. It was concluded that the rigidity and tensile strength of the compound were negatively correlated with temperature. The deformation was a key factor that affects energy loss, which could not be judged solely by the loss factor. The stress distribution, however, should be considered in order to avoid early damage of the tire caused by stress concentration. On the whole, the careful balance of mechanical strength, energy loss, and structural rigidity was the key to the optimal development of run-flat tires. More importantly, the successful implementation of the simulations in the study provided important and useful guidance for run-flat tire development.

The thermal conductivity of flake graphite (FG) particulates reinforced high density polyethylene (HDPE) composites was systematically investigated under a special dispersion state of FG particles. The effects of particle size, weight filling ratio and proportion of various sizes were discussed in detail. A special composite (15 wt % 500 μm/10 wt % 200 μm/10 wt % 20 μm/5 wt % 2 μm FG + 60 wt % polyethylene (PE)) with a high thermal conductivity about 2.49 W/(m·K) was produced by combining the synergistic effect of several fillers. The component material size distribution was employed to analyze the effect of particle size. And scanning electron microscope (SEM) was adopted to observe the FG network in the composites. Thermogravimetric analysis (TGA) revealed the good thermal stability of composites. Differential scanning calorimetry (DSC) indicated that all composites own a similar melting temperature. Sample compression experiment indicated that all composites still exhibit high mechanical strength. Consequently, the easy-making flake graphite reinforced polyethylene composites with a high thermal conductivity would have a wide application in the new material field, such as a thermal interface material, a heat exchanger, voltage cable, etc.

Spent fluid catalytic cracking catalysts (FCC catalysts) produced by the petrochemical industry are considered to be environmentally hazardous waste, and precious metals and heavy metals deposited on the surface make them difficult to treat. Even so, these catalysts retain some of their activity. The pyrolysis of waste tires is considered to be one of the most effective ways to solve the fossil fuel resource crisis, and this study attempts to catalyze the pyrolysis of waste tires using spent catalysts to increase the value of both types of waste. FCC catalysts reduced the activation energy (E) of waste tire pyrolysis. When the catalyst dosage was 30 wt.%, the E of tread rubber decreased from 238.87 kJ/mol to 181.24 kJ/mol, which was a 19.94% reduction. The E of the inner liner decreased from 288.03 kJ/mol to 209.12 kJ/mol, a 27.4% reduction. The spent catalyst was more effective in reducing the E and solid yield of the inner liner made of synthetic rubber. It should be emphasized that an appropriate increase in the heating rate can fully exert the selectivity of the catalyst. The catalyst could also be effectively used twice, and the optimum ratio of catalyst/waste tires was about 1/4.5. Compared with specially prepared catalysts, it is more cost-effective to use such wastes as a catalyst for waste tire pyrolysis.