Deformation behavior of crosslinked polyurea elastomers obtained via sol-gel chemistry: experimental determination and constitutive modelling

Polyurea Networks from Moisture-Cure, Reaction-Setting, Aliphatic Polyisocyanates with Tunable Mechanical and Thermal Properties

“…While for the short polymers, a glassy-like behavior is detected, and the long polymers are in the rubberlike region, as indicated by a master curve obtained using the time−temperature superposition method (Figure S11). For the short aliphatic polyurea networks (P-D230 and P-D400), the presence of the soft domains with reduced mobility greatly affects the viscoplastic behavior 48 of these materials when compared to the reference cured sample P-BHI showing lower elastic modulus values (69 and 45%) while increasing the loss modulus (6 to 7 times), respectively (Table S5). Thus, upon adding these soft segments, a damping component is introduced in the sample while sacrificing a portion of the elastic properties of the P-BHI and making the material less brittle.…”

Solvent free sol-gel based synthesis of soft magnesium silicate

“…2 M(OR)n-1(OH) + M(OR)n-1(OH) → (OR)n-1M-O-M(OR)n-1 + H2O Eq. 3 In contrast to the HSG, the NHSG is based on thermoactivated reactions which uses organic oxygen donors like ether, alcohol, or alkoxide, instead of water [10]. Many mechanisms have been developed for the synthesis of oxides and they can be classified according to the oxygen donor or the nature of the released by-products during the reaction [11,12].…”

“…Commonly used nowadays, the sol-gel process is a method for synthesizing a large number of inorganic compounds for many applications [1][2][3][4]. The method consisted on the formation of an oxide-based network from organometallic or silica precursors.…”

Quasi-Static Mechanical Response of Density-Graded Polyurea Elastomeric Foams

“…In recent years, polyurea foams emerged in the scientific literature as a suitable material candidate for biomechanical impact mitigation applications. ,− Such emphasis was motivated by the contemporary work of Reed et al. , and Ramirez et al, − reporting viable approaches to foam bulk polyurea using spontaneous foaming and heat-activated/controlled foaming methods, respectively. Polyurea is a fascinating class of polymers with several formulations that span the spectrum from linear to cross-linked polymers. − Polyurea, with a specific mixture of diamine and diisocyanate, found favor in the scientific and technological communities for its superior mechanical and thermal properties, including hygrothermal stability, large extensibility, , a broad range of operating temperature, , adhesive properties, − chemical, moisture, and abrasion resistance, and toughness based on its tailored segmental microstructure. − This polyurea formulation was also found to be mildly affected by extended exposure to ultraviolet radiation . Research on bulk polyurea for impact mitigation applications, with an emphasis on military infrastructures and assets, i.e., response to ultrahigh ballistic strain rate, was recently collated by Barsoum. , The latter research culmination showed the momentous promise of this material while signifying polyurea as an interesting scientific testbed.…”

“…Polyurea is a fascinating class of polymers with several formulations that span the spectrum from linear to cross-linked polymers. 37 − 41 Polyurea, with a specific mixture of diamine and diisocyanate, found favor in the scientific and technological communities for its superior mechanical and thermal properties, including hygrothermal stability, 42 large extensibility, 43 , 44 a broad range of operating temperature, 32 , 45 adhesive properties, 46 − 48 chemical, moisture, and abrasion resistance, and toughness based on its tailored segmental microstructure. 49 − 51 This polyurea formulation was also found to be mildly affected by extended exposure to ultraviolet radiation.…”