Origin of Nonlinear Viscoelasticity in Filled Rubbers: Theory and Practice

2014 ◽  
pp. 1-13 ◽  
Author(s):  
Deepalekshmi Ponnamma ◽  
Sabu Thomas
Keyword(s):  
Nonlinear Viscoelasticity ◽  
Theory And Practice ◽  
Filled Rubbers

Filler Network Change and Nonlinear Viscoelasticity of Rubbers

2006 ◽  
Vol 11-12 ◽  
pp. 729-732 ◽  
Author(s):  
Yoshinobu Isono ◽  
Y. Satoh ◽  
Shuji Fujii ◽  
Seiichi Kawahara ◽  
S. Kagami
Keyword(s):  
Electrical Resistivity ◽  
Dynamic Modulus ◽  
Network Formation ◽  
Nonlinear Viscoelasticity ◽  
Large Strain ◽  
Relaxation Modulus ◽  
Network Structures ◽  
Wide Range ◽  
Filled Rubbers ◽  
Filler Network

Uncured, filled rubbers show remarkable nonlinear viscoelasticity as well as cured, filled rubbers. The nonlinearity may come from change in entanglement and filler network structures. Many people use dynamic modulus to characterize rubber materials. However, dynamic modulus cannot be defined at large strain. Hence we must study a viscoelastic function to be defined at large strain. In addition, we need other information to separate the effects of the change in entanglement and filler network structures on nonlinear viscoelasticity. In this work, we have measured simultaneously relaxation modulus G(γ,t) and electrical resistivity ρ(γ,t) for carbon black (CB)-filled, uncured styrene-butadiene copolymers (SBRs) at wide range of strains. Electrical resistivity at equilibrium, ρ(0,t), showed step-like change at the CB loading between 20 and 35 phr, indicating threshold for filler network formation should exist in the range of values in CB loading. Both G(γ,t) and ρ(γ,t) for the samples having CB loading to be higher than the threshold showed nonlinearity at the strain larger than shear strain γ=0.1, indicating rupture in filler network at large strain.

Addressing the Content Vocabulary With Core: Theory and Practice for Nonliterate or Emerging Literate Students

2012 ◽  
Vol 21 (3) ◽  
pp. 74-81 ◽  
Author(s):  
Debbie Witkowski ◽  
Bruce Baker
Keyword(s):  
Communication Skills ◽  
High Performance ◽  
Theory And Practice ◽  
Written Communication ◽  
Academic Tasks ◽  
Meaningful Participation ◽  
Core Theory ◽  
Communication Needs ◽  
Core Vocabulary ◽  
Personal Success

Abstract In the early elementary grades, the primary emphasis is on developing skills crucial to future academic and personal success—specifically oral and written communication skills. These skills are vital to student success as well as to meaningful participation in the classroom and interaction with peers. Children with complex communication needs (CCN) may require the use of high-performance speech generating devices (SGDs). The challenges for these students are further complicated by the task of learning language at a time when they are expected to apply their linguistic skills to academic tasks. However, by focusing on core vocabulary as a primary vehicle for instruction, educators can equip students who use SGDs to develop language skills and be competitive in the classroom. In this article, we will define core vocabulary and provide theoretical and practical insights into integrating it into the classroom routine for developing oral and written communication skills.

The Measurement Invariance of the Short Dark Triad

2020 ◽  
Vol 41 (4) ◽  
pp. 207-218
Author(s):  
Mihaela Grigoraș ◽  
Andreea Butucescu ◽  
Amalia Miulescu ◽  
Cristian Opariuc-Dan ◽  
Dragoș Iliescu
Keyword(s):  
Structural Equation Modeling ◽  
Item Response ◽  
Structural Equation ◽  
Dark Triad ◽  
Theory And Practice ◽  
Equation Modeling ◽  
Scale Level ◽  
High Stake ◽  
Differential Functioning ◽  
Item Functioning

Abstract. Given the fact that most of the dark personality measures are developed based on data collected in low-stake settings, the present study addresses the appropriateness of their use in high-stake contexts. Specifically, we examined item- and scale-level differential functioning of the Short Dark Triad (SD3; Paulhus & Jones, 2011 ) measure across testing contexts. The Short Dark Triad was administered to applicant ( N = 457) and non-applicant ( N = 592) samples. Item- and scale-level invariances were tested using an Item Response Theory (IRT)-based approach and a Structural Equation Modeling (SEM) approach, respectively. Results show that more than half of the SD3 items were flagged for Differential Item Functioning (DIF), and Exploratory Structural Equation Modeling (ESEM) results supported configural, but not metric invariance. Implications for theory and practice are discussed.

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