Two coupled effects of sub micron silica particles on the mechanical relaxation behavior of ethylene–propylene–diene rubber chains

Abstract

This article studied the influence of silica (SiO2) particles on the crosslinked network and the molecular mobility of ethylene-propylene-diene (EPDM) rubber chains by dynamic mechanical analysis (DMA). When SiO2 fraction is lower than 8 phr, the chain segments that participate in the glass-rubber transition (α transition) decrease with increasing the SiO2 content, while the whole crosslinked network is almost unaffected by the presence of SiO2. When the SiO2 fraction increases to about 20 phr, there appears a new tan δ peak (α' transition) above the α transition. This could be because the crosslinking reaction took place only on a small scale and the formed network became gradually incomplete when the content of the particles exceeded some critical value, and the α' transition is attributed primarily to the motion of non-elastic network chains loosely attached to the three-dimensional network. However, at SiO2 loadings higher than 40 phr, the crosslinking density was kept basically constant. The α' transition is hindered by a restriction of the chain mobility due to SiO2. The different changes of α' transition depended on the two coupled effects of SiO2, including restricting the chain mobility and decreasing the crosslinking density. Correspondingly, with increasing the mobility of EPDM chains and SiO2-induced strengthening, the mechanical properties of EPDM composite are dramatically improved. With the addition of 20 phr of SiO2 in the EPDM, a 113% increase in the elongation at break, a 510% increase in the fracture energy, and a 283% increase in the tensile strength are achieved.

Preparation of high‐performance deproteinized natural rubber/chitosan composite films via a green and sulfur‐free method

“…For example, the DSC results showed that the T g increased from −65.3°C of the neat DPNR to −62.3°C of the HP‐DPNR/CS 7 . This phenomenon can be explained by the restriction of rubber chain mobility by CS framework 40,41 . Such slight increase of T g was also reported in some studies that adding chitosan into NR 3,42 .…”

“…This phenomenon can be explained by the restriction of rubber chain mobility by CS framework. 40,41 Such slight increase of T g was also reported in some studies that adding chitosan into NR. 3,42 Similarly, the HP-DPNR/CS also showed a certain resistance to the solvent due to the restriction of rubber chain mobility by CS framework.…”

Skin Adhesives with Controlled Adhesion by Polymer Chain Mobility

“…Figure S3 shows that the soluble fraction F s and the swelling ratio Q decreased with increasing cross-linking agent amounts, which indicates PDMS becomes more cross-linked. 31 To further investigate the relevance between adhesion force and different cross-linking density, we tested the evolution of adhesion force (F) under different retract speeds (Figure 3c). When the cross-linking agent content decreased, the increase of retract speed (ν) during high retract speed (F ∝ ν β ) can cause more increase of the adhesion force (F), from ν 15.9 for the PDMS with 9.1 wt % of cross-linking agent to ν 50.4 for the PDMS with 2.0 wt % of cross-linking agent as the inset shows.…”

“…The soluble fraction F s and the swelling ratio Q are calculated from the relations as follows in which ρ polymer and ρ toluene are the density of the PDMS and the toluene, respectively. Figure S3 shows that the soluble fraction F s and the swelling ratio Q decreased with increasing cross-linking agent amounts, which indicates PDMS becomes more cross-linked . To further investigate the relevance between adhesion force and different cross-linking density, we tested the evolution of adhesion force ( F ) under different retract speeds (Figure c).…”

Tuning the visco-elasticity of elastomeric polymer materials via flexible nanoparticles: insights from molecular dynamics simulation

“…6 Elastomer is a typical kind of visco-elastic materials, attributed to the viscous friction between molecules. 7 For the practical application of automobile tires, nano-sized NPs such as carbon black [8][9][10] or silica [11][12][13] are always introduced to improve the mechanical properties through nanoreinforcement, such as the modulus, tensile and tear strength, abrasion resistance and so on. Since the loading of NPs is high, the aggregate of NPs always occur attributed to the weak interaction between NPs and elastomer, strong van der Walls interaction between NPs and the loss of the conformational entropy of polymer chains in the vicinity of NPs.…”