Abstract:

Associating with the wide use of rubber products especially tires, large volumes of scraps have been generated, which has brought about global environmental problems and public health concerns. It is urgent and of paramount importance to develop technologically feasible and cost-effective routes for recycling waste rubber. It is believed to be one of the most potential ways to reuse the waste rubber in the form of ground rubber powders due to its low cost and less secondary pollutions, which has attracted increasing attentions. However, the obstacle is the relative poorer performances of the final rubber products comparing to those prepared by the raw rubber, which constrains the wide applications of ground rubber powders. To overcome this problem, there are mainly two strategies: one is to improve the whole performances by making surface modification or optimizing the formulations; the other is to endow the final rubber products with the functional properties by composting route.
    As to the modification of waste rubber powders, mechano-chemical activation has been used and the influences of free radicals, processing parameters and activators on de-vulcanization efficiencies have been discussed. The results showed that: 1) The various free radicals had emerged during mechano-chemical modification process due to the broken-up of chemical bonds under strong mechanical shearing forces. The concentration of free radicals increased as the mixing number increased and approached to the highest value, and then gradually decreased as the mixing number increased further. The rubber powders with less particle sizes appeared to be more sensitive to the mechano-chemical modification. 2) The modified robber powders changed into sheet-shapes after mechano-chemical modification. With using them as the starting materials, the blends of rubber powders/ natural rubber have been obtained and they demonstrated best mechanic properties with the contents of rubber powders increasing to the high value of 80phr at the the optimal addtives such as DM 2.5phr, sulfur 0.5 phr and coumatone resin 4.0 phr.
    Focusing on the functionalization of waste rubber powders, the method to composite inorganic magnetic powders with waste rubber powders has been presented based on making improvements on de-vulcanization of rubber powders and refinement of the compatibilities of inorganic and organic phases. The results indicated that: 1) both in-situ surface modifications of inorganic ferrite particles and de-vulcanization of waste rubber powders have been accomplished during the microwave irradiation process. The de-vulcanization efficiency was dramatically improved by increasing the microwave power or prolonging the microwave irradiation time, and gradually decreased if the microwave power or the microwave irradiation exceeded to a limited value. After microwave irradiation, the phase compatibilities of ferrites and rubber matrix have been greatly improved. 2） The contents of ferrite filling in the rubber composites could approach to the highest value of 50.0wt% (100phr) without any additives. After microwave treatment, the inorganic particles were homogenously dispersed in the robber matrix, which demonstrated fine phase compatibilities. The as-fabricated magnetic rubber was characterized by a typical permanent with the saturation magnetization of 31.5emu/g, remnant magnetization of 15.5emu/g and the coercive filed of 1730Oe. After adding additives such as sulfur, accelerator and activator, the phase compatibilities between inorganic fillings and organic matrix were improved further and the cross-linked structures of rubber matrix were integrated completely, the contents of ferrite fillings could achieve to 200phr.
Keywords: rubber powders; reclamation; mechano-chemical activation; functionalization

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Biography:

    Prof. ZHANG Ming was born in Taizhou, Jiangsu Province, on April 1958. Prof. ZHANG Ming is currently Director of Testing Center of Yangzhou University. He also serves as the responsible person of the primary-level discipline of Material Science & Engineering, Yangzhou University. He joined Yangzhou University after graduating from Nanjing University in 1982. He achieved Engineering Ph.D. degree from Northeastern University in 2001. He was a senior visiting scholar at Aichi Institute of Technology, Kyushu Institute of Technology, Toyama University and Kobe University.

    His research interest includes that rare earth-containing functional polymer materials, ordered nano-structured polymer functional materials and dry renewable technology for waste tire.

    He has undertaken a number of national-level research projects, as well as more than 30 provincial-level / ministerial-level research projects and University-enterprise joint research projects. He has published papers in academic journals over 130 articles, including over 80 articles indexed by SCI, EI, ISTP, etc. He also has more than 30 patent applications accepted by SIPO, China. And 15 patents are authorized.

   Prof. ZHANG's research achievements are in the international advance level in the fields of rare earth-containing polymer materials, conductive plastics and waste rubber powder recycle.

   Prof. ZHANG Ming is the member of a council of Chinese Rare Earth Society, China Instrument and Control Society, and Chemistry and Chemical Society of Jiangsu Province. He is the member of professional committee of both Glass Ceramic Branch of Chinese Rare Earth Society and Synthetic Rubber Branch of Chemical Industry and Engineering Society of China. Prof. ZHANG Ming concurrently serves as a member of editorial board of both journal of China Synthetic Rubber Industry and Chinese Journal of Rare Metals.