Organogels containing immobilized shear thickening fluid and their composites with polyurethane elastomer

Abstract

This article concerns investigation on immobilization of shear thickening fluids (STFs) in form of organogel obtained with the use of oligo(propylene glycol) diacrylate (PPGA) as a crosslinking monomer. The STF used was a suspension of nanosilica in oligo(propylene glycol). Organogel particles were prepared by dropwise addition of the STF containing PPGA into silicone oil followed by thermal cross-linking of the monomer. Organogel particles were used to prepare PUR-matrix composite. The rheological properties of organogels and composites were studied by oscillatory measurements. The measurements showed significant changes in internal structure of the samples, which are most likely connected with shear thickening. It was demonstrated that manufactured composites exhibited 20% higher impact absorption than that of cast polyurethane elastomer. Presented method of STF immobilization allows to obtain organogel particles that can be widely used for intelligent materials preparation due to their good stability and impact absorption ability.

Rheological and Technological Aspects in Designing the Properties of Shear Thickening Fluids

“…Silica is a primary choice as a solid phase for STF production [ 16 , 33 , 34 ], but other raw materials such as corn starch [ 35 ], calcium carbonate [ 36 ], titanium dioxide [ 37 ], polymethyl methacrylate [ 38 ], polystyrene [ 39 ], or ethyl polystyrene acrylate [ 40 ] are also used for this purpose. The continuous phase of an STF is usually ethylene glycol [ 41 , 42 ], poly(ethylene glycol) [ 32 , 43 , 44 ], propylene glycol [ 41 ], or poly(propylene glycol) [ 7 , 45 , 46 , 47 ]. There are also reports on the application of glycerin [ 48 ], ethanol [ 37 ], and even water [ 49 ].…”

How a Gel Can Protect an Egg: A Flexible Hydrogel with Embedded Starch Particles Shields Fragile Objects Against Impact

“…Is this property of shear-thickening related to impact absorption? Shear-thickening fluids (STFs) have been introduced into fabrics such as Kevlar and shown to enhance the fabric’s resistance to stabbing with knives or other sharp objects. − There have been a couple of recent studies on foams and elastomers containing STFs in the context of impact absorption, but none of these systems were hydrogels and none used starch suspensions as the STF. ,, When particles such as starch are in a gel matrix, they will be immobilized and unable to flow. Thus, the gel cannot exhibit shear-thickening, unlike a flowing suspension.…”

“…29−32 There have been a couple of recent studies on foams and elastomers containing STFs in the context of impact absorption, but none of these systems were hydrogels and none used starch suspensions as the STF. 27,28,33 When particles such as starch are in a gel matrix, they will be immobilized and unable to flow. Thus, the gel cannot exhibit shear-thickening, unlike a flowing suspension.…”

The Mechanical Properties of Silicone Rubber Composites with Shear Thickening Fluid Microcapsules

“…Liu et al added a sodium alginate solution and Span 20 to the STF paraffin solution containing Span 80, then the mixture was dropped into anhydrous calcium chloride aqueous solution using a syringe to prepare STF capsules [ 16 ]. Kaczorowski et al adopted polypropylene glycol diacrylate as a monomer to prepare a slightly crosslinked shear thickening liquid organic gel and then embedded it into the uncured polyurethane mixture to form STF/polyurethane elastomer composites [ 17 ]. Soutrenon et al used the vacuum resin infusion method to infiltrate STFs into foam and then covered the outer layer with silicone rubber to achieve the encapsulation of STF/foam composites [ 18 ].…”