Performance, Structure, And Application Of NR/TPI Blends

Trans-1,4 - polyisoprene (TPI) is a synthetic rubber with high hardness, heat low dynamics, anti-abrasion performance and superior dynamic fatigue properties. NR has excellent processing performance, high flexibility, and excellent performance. However, it also has some defects, such as bad dynamic properties, higher loss, bad thermo-oxidative aging, lower hardness and set extension.Both TPI and NR are isoprene, so they have a good compatibility, blending TPI with NR can remedy the defects of NR. In this paper, the relationship between structure and properties of NR/TPI was studied, which laid a theoretical basis for obtaining high-performance materials and exploring the application of TPI.In the second chapter, effects of TPI dosage, processing technology, carbon black, silica and their contents on aggregation structure and physical and mechanical properties of NR/TPI blends were studied. Aggregation structure of TPI in NR/TPI blends was investigated by the polarizing microscope, thermal analysis, infrared spectra, and electronic scanning microscop.The main results were as follows:Polarized light microscopy showed that, when the content of TPI was 20phr, the spherulite of TPI in NR/TPI blends became continuous phase. At the same time, NR/TPI vulcannizates had best dynamic fatigue performance. Thermal analysis showed that, before curing, the compound agent and carbon black had no obvious effect on the TPI crystallinity by pure plastic blends. After curing, crystallinity of TPI in NR/TPI decreased observably, however, there were still some remnants of the crystallization,and crystallinity increased as increasing the contents of TPI in NR/TPI blends. Infrared analysis showed that, after curing, characteristic peaks of TPI crystal weakened clearly, which also meant that the main cause of damage to the crystallization of TPI was vulcanization. The investigation of SEM showed that, the residual crystal of TPI distributed in form of grain in the amorphous region, the number and size of which increased with increasing of TPI content; Grains dispersed in NR / TPI blends in the role of physical crosslinking points and made up for deficiencies of system.The addition of carbon black is in the double role of reinforcement and damage of crystallization of TPI. Research results showed that, when the dosage of TPI was 20 phr, crystallinity of TPI in NR/TPI blends decreased from 1.74% to 1.18% with the addition of carbon black; wear performances of NR filled with carbon black, NR/TPI filled with carbon black, NR/TPI without carbon black were investigated, and the results showed that, the abrasion value of the rubber of NR/TPI filled with carbon black was minimum, which meant that both microcrystalline of TPI and carbon black improved the wear performances of NR/TPI blends. Research results of types of carbon black and amounts of carbon black, silica showed that, when selected carbon black of N330, silica / carbon black was 20/30, wear rubber, dynamic fatigue, hardness, strength and thermo-oxidative aging of NR./TPI blends were improved.In order to investigate the dispersion of carbon black in NR / TPI blend , four mixing process were studied using RPA, and the results showed that, the amount of bound rubber, hardness, set extension and tensile strength of NR/TPI were higher when selected mixing process of TPI and NR mixing + carbon black + agent.In the third and forth chapter, the application of NR/TPI blends in wiper and tennis was studied. The results showed that, when the content of TPI was 18phr, silica / carbon black was 20/30 in NR/TPI blends, anti-abrasion and thermo-oxidative aging of NR/TPI increased by 30.6% and 20%, Flex fatigue properties were also improved because of making up for deficiencies on the system by TPI-ceramics, and the contribution of silica for the reinforcement of network structure. When contents of TPI in the tennis was 18phr, Resilience of NR/TPI decreased by 2.7%, Modulus at 200% and Hardnss of NR/TPI increased by 43.1% and 7.1%, because of the resilience of TPI molecular as well as the improvement of cross-linking density.