Shear thinning molecular dynamics simulation of binder solution for 3D printing alumina. Issue 19 (1st October 2022)

• Record Type: Journal Article
• Authors: Zhao, Jingjing; Yang, Daoyuan; Li, Xing; Luo, Jiahua; Bai, Xiaosong; Hao, Mingxuan; Cui, Junyan; Yuan, Huiyu; Wang, Hailong; Shao, Gang
• Is Part Of: Ceramics international. Volume 48:Issue 19(2022)Part A
• Page Start: 27302
• Page End: 27311
• Publication Date: 2022-10-01
• Subjects: 3D printing paste binders -- Shear-thinning ability -- Molecular orientation configuration -- Hydrogen bond; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.01.099
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: To simulate and analyze the effects of binder on the shear thinning ability of water-based alumina ceramic pastes for 3D printing, the single chain molecular weight of binders was set as 1825 (±20), the polymerization degree of the binder molecules containing polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyacrylamide (PAM) and carboxymethyl cellulose (CMC) was then set as 41, 41, 26 and 8 respectively via Materials Studio software (MS). The solutions consisting of 10 binder molecules and 1000 H2 O molecules were built as the objects to carry out the all-atom molecular dynamics simulation. The mechanism of solution shear thinning was elucidated by analyzing the parameter of shear viscosity, molecular orientation configuration, radius of gyration distribution, diffusion coefficient and hydrogen bonding. Results show that the solution viscosity decreased by 17.828 mPa s (CMC), 16.551 mPa s (PAM), 6.744 mPa s (PVA), and 2.642 mPa s (PEG) respectively, when the shear rate was in range of 0.001–0.01 ps -1, all exhibiting good shear thinning ability. The order of shear-thinning ability was: CMC > PAM > PVA > PEG. The radius of gyration distribution range of unit chain length was 0.1504 Å (CMC), 0.1035 Å (PAM), 0.0758 Å (PVA), and 0.0618 Å (PEG), indicating that the shear-thinning ability was related with the radius of gyration distribution. As the shear rate increased, the diffusion coefficient of molecules was increased significantly. Besides, the straight-chain or directionally aligned molecules moved easily, and molecules with branched chains or ring structure moved slowly, which directly affect the shear thinning ability of binders. The average weakening degree of hydrogen bonding at 0.01 ps -1 compared with steady state was 7.9% (PVA), −4.1% (PEG), 44.6% (PAM) and 47.6% (CMC). The weakening of hydrogen bonding plays an important role in improving the shear thinning ability.