Structure And Properties Of Polyolefin/GTR Blended By Reactive Extrusion

The limitation of crude oil and environmental pollution bring the waste resources a great challenge, in which, the ground tire rubber resource becomes a main target of resolving these issues. However, according to the three-dimensional network structure, the vulcanized rubber cannot using the melt processing in the recycling of plastic and steel, this is the biggest obstacle of effectively reusing the waste resources.This paper studied the polyolefin / ground rubber blends can be prepared by mixing the ground tire rubber with polyolefin plastics. Based on the reasonable matrix and formula, the blends with good elasticity and reprocessing capability can be obtained by optimizing the melt processing conditions, and achieved the waste disposal and resource recycling. The solution of preparing the blends with nice performance was achieved by focusing on the structural changes of vulcanized rubber phase, and through developing the proper processing methods.Firstly, different matrixes were studied to find a suitable blending system for GTR, and it was discovered that the blends with polyolefin matrix had better performance both in mechanical strength and elasticity than those with polystyrene or high impact polystyrene blends. The blend with LLDPE obtains the best mechanical properties; especially the elongation at break exceeds 100%. In addition, the ratio of polyolefin / rubber was also analyzed. Although the overall performance of the blends shows a downward trend along with the increase of GTR content, the blends with 70 phr GTR has a reasonable strength and elongation at break as a potential choice of preparing elastomer material. Secondly, the dynamic change of the particles size was studied in different processing conditions. The results show that the performance of the blends is mainly affected by the size of the dispersed phase and its uniformity. Meanwhile, the particle size of the dispersed phase is sensitive to the shear strength and temperature in the process. It is the foundation of the reactive extrusion process approach.Thirdly, LLDPE / GTR blends were prepared by the reactive extrusion - dynamic vulcanization processing method. This method employs a twin-screw extruder to achieve the mixture of LLDPE and GTR, while partially desulfurized the rubber powder. After that the dynamic vulcanization was used to provide good performance for the final product. The results show that the dynamic vulcanization process not only recovers the degradation of the cross-linked structure, but also there brings mechano-chemical effect between GTR and LLDPE.Finally, the processing conditions were studied to investigate its relationship with the structure and properties of the blends. The screw speed of 100-200 rpm and processing temperature below 200 oC can obtain the blends with good mechanical properties. In addition, although the introduction of desulfurizer improves the effect of desulfurization, it cannot be reflected on the properties of the blends.