Molecular Simulation on Miscibility of NR/BR Blends

doi:10.3969/j.issn.1000-2561.2022.11.005

Abstract

Abstract:

Natural rubber (NR) is widely used in various fields for its excellent comprehensive properties, however its poor heat resistance and aging resistance have great influence on the service life of NR products. The blending of natural rubber and cis-butadiene rubber (BR) could not only improve the tensile strength, wear resistance and tear resistance of the product, but also improve the service life and cold resistance of the product, and the NR/BR blends are widely used in tire manufacturing. When NR and BR are blended, the miscibility between NR and BR has an important influence on the phase structure and properties of the blends. In this study, Material Studio software was used to build the models required for the simulation, and molecular dynamics (MD) and dissipative particle dynamics (DPD) simulation methods were performed to investigate the miscibility of NR/BR blends from the molecular and mesoscopic scales at room temperature. The MD simulation results showed that the minimum repeating units of NR and BR in the NR/BR blend models were both 20; Models of NR/BR blends with mass ratios of 10/90, 30/70, 50/50, 70/30, 90/10 were constructed by Material Studio, by calculating the interaction parameter χ of each NR/BR blends, it was found that the interaction parameters of NR-BR in NR/BR blends (χ_NR/BR) were always smaller than the critical interaction parameter χ_C; The radial distribution function between molecules of NR/BR blends with different mass ratios were analyzed, and it was found that the radial distribution function g_inter(r) between NR and BR molecules were always higher than that between NR and NR, BR and BR molecules of the same species, which showed that the interaction between different species (NR-BR) in the blends is stronger than the interaction between the same species (NR-NR, BR-BR). In addition, DPD simulations results calculated from the NR/BR blends with different mass ratios showed that the domain size of the dispersed phase of the blends increased with the increase of the dispersed phase content while macroscopic phase separation had always not been detected. Furthermore, the samples of NR/BR blends were prepared, and the miscibility of each blending system was confirmed with the results of dynamic mechanical analysis (DMA). The simulation results show that when NR and BR are blended with different mass ratios at room temperature, they always show good compatibility, and the experimental results are consistent with the results of molecular simulation.For this reason, molecular simulation will be of significance to study and predict the miscibility of polymer blend, and it will provide much more reliable guidance for experiment.

Key words: natural rubber, cis-butadiene rubber, molecular dynamics, dissipative particle dynamics, miscibility

CLC Number:

YUAN Xiaoqin, CAO Xianchao, MA Yanbin, YU Rentong, ZHAO Yanfang, CHEN Yongping, LIAO Jianhe. Molecular Simulation on Miscibility of NR/BR Blends[J]. Chinese Journal of Tropical Crops, 2022, 43(11): 2215-2223.

Figures/Tables 10

References 27

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名称 Name	相对分子量 Relative molecular mass	极限特征比$C_{ \infty}$	粒子数 N_DPD
NR	350 000	5.45	810
BR	120 000	5.60	496

名称 Name	相对分子量 Relative molecular mass	极限特征比$C_{ \infty}$	粒子数 N_DPD
NR	350 000	5.45	810
BR	120 000	5.60	496

序号 No.	NR/BR质量比 NR/BR mass ratio	相互作用 Interation/(KJ·mol^-1)
1	10/90	25.130
2	30/70	25.021
3	50/50	24.993
4	70/30	25.103
5	90/10	24.160

序号 No.	NR/BR质量比 NR/BR mass ratio	相互作用 Interation/(KJ·mol^-1)
1	10/90	25.130
2	30/70	25.021
3	50/50	24.993
4	70/30	25.103
5	90/10	24.160

NR/ BR	$\varphi_{NR}$/%	$\varphi_{BR}$/%	CED_NR/ (×10⁸J·m^-3)	CED_BR/ (×10⁸J·m^-3)	CED_mix/ (×10⁸J·m^-3)	△E_mix/ (J·m^-3)
10/90	10.35	89.65	2.68	2.96	2.93	3.33E+05
30/70	29.76	70.24	2.68	2.96	2.88	4.62E+04
50/50	50.42	49.58	2.68	2.96	2.82	-1.47E+04
70/30	69.55	30.45	2.68	2.96	2.77	2.08E+05
90/10	89.87	10.13	2.68	2.96	2.73	-1.60E+06