Hapipi Norhiwani Mohd, Mazlan Saiful Amri, Ubaidillah Ubaidillah, Abdul Aziz Siti Aishah, Choi Seung-Bok, Nordin Nur Azmah, Nazmi Nurhazimah, Pang Zhengbin, Mohd Yusuf Shahir
Engineering Materials and Structures (eMast) iKohza, Malaysian-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia.
Mechanical Engineering Department, Faculty of Engineering, Universitas Sebelas Maret, Jl. Ir. Sutami 36A Kentingan Jebres, Surakarta 57126, Indonesia.
Sensors (Basel). 2021 Nov 22;21(22):7758. doi: 10.3390/s21227758.
Polyvinyl alcohol (PVA)-based magnetorheological plastomer (MRP) possesses excellent magnetically dependent mechanical properties such as the magnetorheological effect (MR effect) when exposed to an external magnetic field. PVA-based MRP also shows a shear stiffening (ST) effect, which is very beneficial in fabricating pressure sensor. Thus, it can automatically respond to external stimuli such as shear force without the magnetic field. The dual properties of PVA-based MRP mainly on the ST and MR effect are rarely reported. Therefore, this work empirically investigates the dual properties of this smart material under the influence of different solvent compositions (20:80, 40:60, 60:40, and 80:20) by varying the ratios of binary solvent mixture (dimethyl sulfoxide (DMSO) to water). Upon applying a shear stress with excitation frequencies from 0.01 to 10 Hz, the storage modulus (G') for PVA-based MRP with DMSO to water ratio of 20:40 increases from 6.62 × 10 to 0.035 MPa. This result demonstrates an excellent ST effect with the relative shear stiffening effect (RSTE) up to 52,827%. In addition, both the ST and MR effect show a downward trend with increasing DMSO content to water. Notably, the physical state of hydrogel MRP could be changed with different solvent ratios either in the liquid-like or solid-like state. On the other hand, a transient stepwise experiment showed that the solvent's composition had a positive effect on the arrangement of CIPs within the matrix as a function of the external magnetic field. Therefore, the solvent ratio (DMSO/water) can influence both ST and MR effects of hydrogel MRP, which need to be emphasized in the fabrication of hydrogel MRP for appropriate applications primarily with soft sensors and actuators for dynamic motion control.
基于聚乙烯醇（PVA）的磁流变塑性体（MRP）在受到外部磁场作用时具有优异的磁致机械性能，如磁流变效应（MR效应）。基于PVA的MRP还表现出剪切硬化（ST）效应，这在制造压力传感器方面非常有益。因此，它可以在没有磁场的情况下自动响应外部刺激，如剪切力。基于PVA的MRP主要基于ST和MR效应的双重特性鲜有报道。因此，本工作通过改变二元溶剂混合物（二甲基亚砜（DMSO）与水）的比例，实证研究了这种智能材料在不同溶剂组成（20:80、40:60、60:40和80:20）影响下的双重特性。在施加频率为0.01至10Hz的剪切应力时，DMSO与水比例为20:40的基于PVA的MRP的储能模量（G'）从6.62×10增加到0.035MPa。该结果表明具有高达52,827%的相对剪切硬化效应（RSTE）的优异ST效应。此外，随着DMSO含量相对于水的增加，ST和MR效应均呈下降趋势。值得注意的是，水凝胶MRP的物理状态可随不同溶剂比例在液态或固态之间变化。另一方面，瞬态逐步实验表明，作为外部磁场的函数，溶剂组成对基质内CIPs的排列有积极影响。因此，溶剂比例（DMSO/水）会影响水凝胶MRP的ST和MR效应，这在主要用于动态运动控制的软传感器和致动器的水凝胶MRP制造中需要加以强调。
