Influence of microphase separation and crosslinking density on dynamic viscoelastic properties of nano‐Fe₃O₄ modified polyurethane

Abstract

Although there have been some studies on the preparation and characteristics of nano‐Fe3O4‐filled polyurethane (PU) composites, research focusing on the quantitative influence of the degree of microphase separation (DPS) and the crosslinking density (CLD) on dynamic viscoelastic properties is rare. In this paper, PU composites are synthesized by incorporating nano‐Fe3O4 as fillers. The dynamic mechanical properties under alternating loads are investigated using dynamic mechanical analysis. The influences of the DPS and the CLD on the dynamic hysteresis loss are analyzed. The experimental results show that the DPS and CLD of PU nanocomposites increase and then decrease with the increase of nano‐Fe3O4 addition and reached a maximum at the addition amount of 1.0 wt%. The quantitative relationships between DPS, CLD and the dynamic hysteresis loss of PU nanocomposites at different filler ratios are obtained. With a 1.0 wt% nano‐Fe3O4 content, the strain energy density (SED) and hysteresis energy density (HED) are increased by 416% and 354%, respectively. The hysteretic loss H indexes of all composites are kept lower than that of pure PU. These characteristics make nano‐Fe3O4‐filled PU a promising material for reducing the rolling resistance and increasing the service life of fuel‐saving tire materials.

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“…Besides, silicone oil in the carbon grease can decrease the modulus of the electrode . Generally, the DMP of elastomer composite materials can be tailored by changing the type of elastomer matrix, the filling fraction of fillers, the type and surface properties of fillers, − the vulcanization system and cross-linking density, − or the degree of aging . Among them, modifying the cross-linking density of SRE is the most effective method with minimal impact on conductivity.…”

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“…The peak temperature of the loss angle tangent is taken as T g . The crosslinking density ( υ e ) was calculated by Equation (2) with the storage modulus of the rubbery plateau obtained by DMA [ 29 , 30 , 31 ]. where E r is the storage modulus of the rubbery plateau, Pa; R is the gas constant; T is taken as T g + 30, K.…”

“…The peak temperature of the loss angle tangent is taken as Tg. The crosslinking density (υe) was calculated by Equation ( 2) with the storage modulus of the rubbery plateau obtained by DMA [29][30][31].…”