Abstract:

The rheological behavior, characterization of the aging behavior, kinetics of vulcanization and mechanical properties of natural rubber coagulated by microorganisms (NR-m) was studied. The thermal and thermooxidative degradation kinetics of NR-m in nitrogen and air was investigated by thermogravimetry analysis (TG) and differential thermal analysis (DTA). The results showed that the effect of temperature on viscosity of raw NR followed the Arrhenious-Frenkel-Eyring model. The storage torque, complex viscosity of NR-m were higher than those of natural rubber coagulated by acid (NR-a) while the loss factor was lower. The viscous flow behavior of NR-m was poorer than those of NR-a. With the prolongation of the aging time, the storage modulus, storage torque, and complex viscosity of raw NR-m decreased while the loss modulus were increased. In the induction period of vulcanization, the time t0 of NR-m is shorter than that of natural rubber coagulated by acid (NR-a). Both the curing periods of NR-m and NR-a consist of two stages. The first stage follows first-order reaction, while the second stage (end stage of the curing period) does not follow first-order reaction. The modulus, tensile strength, tearing strength and hardness (shore A) of NR-m is markedly higher than those of NR-a. The results of thermal analysis indicate that the thermal degradation of NR-m in nitrogen is significantly different from the thermooxidative degradation of NR-m in air. There is only one-stage in the thermal degradation reaction of NR-m, while thermooxidative degradation of NR-m in air is a two-stage reaction. The initial temperature of weight loss (T0) and the peak temperature of weight loss（Tp）as well as the reaction activation energy (Ea) of NR-m are higher than those of nature rubber coagulated by acid (NR-a).

Keywords: natural rubber, microorganism coagulation, rheological properties; kinetics of vulcanization; mechanical properties; thermal degradation

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Biography:

Shuangquan Liao is the professor and the vice dean of College of Materials and Chemical Engineering of Hainan University.
Study and Work Experience
South  China University of Tropical Agriculture, Bachelor, Storage and Processing of Agricultural Products, July, 1996
South China University of Tropical Agriculture, Master, Agricultural Products Processing and Storage Engineering, July, 1999
Beijing Institute of Technology, Ph. D, Material Science, August, 2002
Edinburgh University, UK, Postdoctor, Organic Chemistry, September, 2006-September, 2007
South China University of Tropical Agriculture, Lecturer, September, 1999-August, 2002
South  China University of Tropical Agriculture, Associate Prof. and Assistant Dean, September, 2002-January, 2005
South China University of Tropical Agriculture, Associate Prof. and Associate Dean, January, 2005-September, 2007
Hainan University, Associate Prof. and Associate Dean, October, 2007-October, 2009
Hainan University, Haikou, Hainan Province, Prof. and Associate Dean, October, 2009-

Research Interest
1.Green processing technology of natural rubber
2.Morphological character and distribution of rubber particles of natural rubber latex
3.Preparation of fast coagulator for coagulating field latex
4.Preparation of  liquid natural rubber and application as a processing agent and a cross-linking agent
5.Preparation of water-swelling rubber and relationships between structure and characteristics
6.Processing technology for improving skim natural rubber performance

Dr. Liao was the recipient of research grants from Key Projects in the National Science & Technology Pillar Program during the Twelfth Five-year Plan Period and NSCF and NSCF of Hainan Province and other projects. He has the author or co-author of beyond 80 publications and applied 15 and awarded 8 invent patents. Currently, he is the director of the general office of Hainan Policy and Industrial Research Institute of Low-Carbon Economy and assist Hainan Development and Reform Commission and to work together with them in combating climate change and studying on the development model of low-carbon in Hainan. He is the committee member of Chemical Industry and Engineering Society of China（2013），and the committee member and technical program committee member of international rubber conference(2014).