Preparation and performance investigation of shear thickening liquid microcapsules

doi:10.19491/j.issn.1001-9278.2024.01.006

Abstract

Abstract:

In this study， STF microcapsules （STF MCs） were prepared by using a monocoalescence method with chitosan material as a wall material and STF as a core material. The process parameters for the preparation of microcapsules were determined by a single⁃factor experimental study. Span 80 and Tween 80 were used as dispersants at a mass ratio of 3∶1， the addition amount of emulsifier was determined to be 11 wt%， the mass ratio of core to shell was determined to be 2∶1， the stirring speed was 600 r/min， the reaction temperature was 60 ℃， and the oil⁃to⁃water mass ratio of the system was 1∶2. The STF MCs produced under these conditions show a relatively regular spherical morphology with a relatively uniform distribution centered as a particle size of 3 μm. Rheological results indicated that the introduction of carbon nanotubes （CNTs） effectively improved the rheological properties of STFs. The CNTs⁃doped STF system exhibited a smaller critical shear rate， a faster viscosity transition， and an almost doubled peak viscosity. Infrared spectroscopic results indicated that the infrared spectrum of the microcapsule emulsion was almost consistent with that of the core. This indicated that chitosan was successfully adsorbed on the surface of the core droplets to realize the encapsulation of STFs. Thermogravimetric analysis results indicated the wall material could provide protection for the STF core， thus enhancing its thermal stability.

Key words: shear thickening liquid, microcapsule, complex coagulation method, single?factor filtering, protective performance

CLC Number:

TQ320.66

YU Bo, ZHAO Bingqian, NI Yezhou, QIAN Kun, YU kejing, CHEN Kunlin. Preparation and performance investigation of shear thickening liquid microcapsules[J]. China Plastics, 2024, 38(1): 35-41.

Figures/Tables 11

乳化剂种类	质量比	HLB值	含量/g	乳化结果评价
Span 80	—	4.3	0.2	乳液粒子稍大
Tween 80	—	15	0.2	乳液聚结
Span 80∶Tween 80	1∶1	9.7	0.2	乳液聚结
Span 80∶Tween 80	2∶1	7.9	0.2	乳液粒子小
Span80∶Tween 80	3∶1	7.0	0.2	乳液粒子小且均匀
Span 80∶Tween 80	4∶1	6.4	0.2	乳液粒子稍大，且存在一定黏连情况

Tab.1. Evaluation of the properties of colostrums prepared from different emulsifiers

Fig.1. Polarizing microscopy of W/O colostrum prepared from different emulsifiers

Fig.2. Effect of emulsifier content on particle size of microencapsulated colostrum

Fig.3. Effect of core⁃shell ratio on the average particle size of microcapsules

搅拌转速/r·min^-1	乳化剂含量/%	平均粒径/nm	PDI
200	11	3 096	0.896
400	11	2 968	0.659
600	11	2 776	0.598
800	11	2 710	0.546
1 000	11	2 656	0.516

Tab.2. Effect of stirring speed on particle size and particle size distribution of the microcapsules

Fig.4. Effect of oil⁃water ratio on particle size of the microcapsules

Fig.5. SEM of SiO2 and rheological diagrams of the base system and the doped carbon tube system

Fig.6. Microscopic morphology and normal distribution of the microcapsules

Fig.7. EDS spectroscopy analysis of the microcapsules

Fig.8. FTIR of the microcapsules， their core materials and wall materials

Fig.9. TG curves of the sample

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