Transitions and Relaxations

Myasnikova, L. P.

doi:10.1002/0471440264.pst375

Cited by 3 publications

(2 citation statements)

References 128 publications

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“…Moreover, T g increases slightly (Table 4), which may be assigned to the fact that the segmental relaxations are slowed down due to the restriction effect caused by the presence of crystalline part. [26,27] It should be emphasized that T m of the vulcanizates remains unchanged by varying the cooling rate, but is significantly lower than that of the uncured T A B L E 3 Calorimetric results from DSC for the uncured compounds samples. This can be attributed to steric hindrance of chain folding caused by network formation.…”

Section: Segmental Mobility Evaluation By Dscmentioning

confidence: 99%

Segmental relaxations and other insights into filler‐mediated interactions for carbon black‐filled polybutadiene rubber

Zhang

Zhou

2020

J of Applied Polymer Sci

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The role of interaction with filler particles in modifying segmental relaxations of elastomers is still not fully clear. This work examines the glass and melting transition of unvulcanized and vulcanized polybutadiene rubber filled with carbon black. It is found that for uncured rubbers, the calorimetric glass and melting transition temperatures are unaffected by the presence of carbon black, without invoking the concept of restricted chains near filler. In quenched vulcanizates, the increment in segmental relaxation with filler loading is detected, which is attributed to the reduction in chemical crosslink density caused by filler agglomeration. On the other hand, the crystalline part constrains the molecular motion in amorphous regions such that the glass transition temperature is raised when the crystallinity is large. This study reveals that the only effect of carbon black is to influence chemical crosslinks through filler networking and then change in segmental relaxations is detectable.

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Section: Segmental Mobility Evaluation By Dscmentioning

confidence: 99%

Segmental relaxations and other insights into filler‐mediated interactions for carbon black‐filled polybutadiene rubber

Zhang

Zhou

2020

J of Applied Polymer Sci

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“…The loss modulus peak centered at −192°C corresponds to γ transition. According to Myasnikova [26] several works, published in recent years, give a significant progress concerning the β and γ relaxation mechanisms. These studies established relationships between the β and γ relaxation parameters and the internal state of polymers at the molecular level.…”

Section: Resultsmentioning

confidence: 99%

Constitutive modeling of polycarbonate during high strain rate deformation

Safari

Zamani

Ferreira³

et al. 2012

Polymer Engineering & Sci

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A constitutive model is presented for large strain deformation of polycarbonate (PC) at high strain rates (above 102 s−1). The proposed model considers the primary process (α) and the two secondary rate‐activated processes (β and γ). It is shown that the secondary transitions in the material affect the yield and post yield behavior of the material at high strain rates. The constitutive model has been implemented numerically into a commercial finite element code through a user material subroutine. The experimental results, obtained using a split Hopkinson pressure bar, are supported by dynamic mechanical thermal analysis (DMTA) and DSR (Decompose/Shift/Reconstruct) method. These are employed to gain understanding of the material transitions, and to further the linkages between material viscoelastic, yield, and stress–strain behavior. Comparison of model predictions with experimental data demonstrates the ability of model to capture the characteristic features of stress–strain curve of the material such as initial linear elasticity, global yield, strain softening, and strain hardening at very high strain rates (up to 10,000 s−1). POLYM. ENG. SCI. 2013. © 2012 Society of Plastics Engineers

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