Creep and stress relaxation in methacrylate polymers: Two mechanisms of relaxation behavior across the glass transition region

2001 ◽  
Vol 41 (5) ◽  
pp. 873-880 ◽  
Author(s):  
P. R. Higgenbotham-bertolucci ◽  
H. Gao ◽  
J. P. Harmon
Keyword(s):  
Glass Transition ◽  
Stress Relaxation ◽  
Transition Region ◽  
Relaxation Behavior ◽  
Glass Transition Region ◽  
Methacrylate Polymers ◽  
Creep And Stress Relaxation

scholarly journals Buckling and vibration analysis of shape memory laminated composite beams under axially heterogeneous in-plane loads in the glass transition temperature region

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Nilesh Tiwari ◽  
A. A. Shaikh
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Boundary Conditions ◽  
Shape Memory ◽  
Transition Region ◽  
Shape Memory Polymer ◽  
Shear Deformation Theory ◽  
Effect Of Temperature ◽  
Glass Transition Region

AbstractBuckling and vibration study of the shape memory polymer composites (SMPC) across the glass transition temperature under heterogeneous loading conditions are presented. Finite element analysis based on C° continuity equation through the higher order shear deformation theory (HSDT) is employed considering non linear Von Karman approach to estimate critical buckling and vibration for the temperature span from 273 to 373 K. Extensive numerical investigations are presented to understand the effect of temperature, boundary conditions, aspect ratio, fiber orientations, laminate stacking and modes of phenomenon on the buckling and vibration behavior of SMPC beam along with the validation and convergence study. Effect of thermal conditions, particularly in the glass transition region of the shape memory polymer, is considerable and presents cohesive relation between dynamic modulus properties with magnitude of critical buckling and vibration. Moreover, it has also been inferred that type of axial loading condition along with the corresponding boundary conditions significantly affect the buckling and vibration load across the glass transition region.

Dynamic mechanical behaviour of a polysulfone in the glass transition region

1988 ◽  
Vol 20-21 (1) ◽  
pp. 451-460 ◽  
Author(s):  
E. Macho ◽  
J. M. Alberdi ◽  
A. Alegría ◽  
J. Colmenero
Keyword(s):  
Glass Transition ◽  
Transition Region ◽  
Mechanical Behaviour ◽  
Glass Transition Region ◽  
Dynamic Mechanical

Thermal Analysis of Nomex® and Kevlar® Fibers

1977 ◽  
Vol 47 (1) ◽  
pp. 62-66 ◽  
Author(s):  
J. R. Brown ◽  
B. C. Ennis
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Glass Transition ◽  
Melting Point ◽  
Transition Region ◽  
High Temperatures ◽  
High Performance ◽  
Polymer Melt ◽  
Glass Transition Region ◽  
Dta Curves

DTA, TG, and TMA curves of commercial Kevlar® 49 and Nomex® fibers have been used to assess their behavior at high temperatures. The fibers lost absorbed water around 100°C, and a glass transition was reflected in the DTA and TMA curves in the region of 300°C. Difficulties in the interpretation of DTA and TMA curves in the glass-transition region and in the assignments of Tv‘s for these high-performance fibers are discussed. Whereas Kevlar 49 showed both a crystalline melting point (560°C) and a sharp endothermal thermal decomposition (590°C), Nomex showed only the latter (440°C) and no evidence of melting from the DTA curves. The endothermal decomposition peaks apparently correspond to “polymer melt temperatures” reported for related materials, and correlate well with the TG and TMA features. During thermal analysis of Kevlar 49, oxidation occurs more readily than thermal decomposition, but the latter predominates for Nomex. Differences between dyed and undyed Nomex were due to differences in yarn constitution.

Dynamic light scattering study of poly(di-n-butyl itaconate) in the glass transition region

Polymer ◽  
1991 ◽  
Vol 32 (11) ◽  
pp. 1928-1934 ◽  
Author(s):  
Tzyy-Lung Yu ◽  
K Devanand ◽  
A.M Jamieson ◽  
R Simha
Keyword(s):  
Glass Transition ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Transition Region ◽  
Glass Transition Region ◽  
Scattering Study

Comparative Study of Creep and Stress Relaxation Behavior for 7055 Aluminum Alloy

2011 ◽  
Vol 314-316 ◽  
pp. 772-777 ◽  
Author(s):  
Li Hua Zhan ◽  
Yan Guang Li ◽  
Ming Hui Huang ◽  
Jian Guo Lin
Keyword(s):  
Aluminum Alloy ◽  
Creep Rate ◽  
Stress Relaxation ◽  
Relaxation Rate ◽  
Constitutive Equations ◽  
Relaxation Behavior ◽  
Experimental Results ◽  
Stress Relaxation Behavior ◽  
Creep And Stress Relaxation ◽  
7055 Aluminum Alloy

In order to study the similarities and dissimilarities between creep and stress relaxation behavior of age formed aluminum alloys, both creep ageing and stress relaxation ageing experiments have been conducted with plate shaped 7055 aluminum alloy specimens on the 100 KN tensile testing machine performed at 120 °C for 20 h, under different stress levels from 190.0 to 357.8 MPa. The experimental results show that similar variation trends for creep and stress relaxation behavior were observed. Both creep and stress relaxation curves can be divided into two stages. During the first stage, higher creep rate and stress relaxation rate occur, which increase with stress levels but decrease with ageing time. While during the second stage, both the creep rate and the stress relaxation rate reach its lowest value and keep constant. A set of unified creep ageing constitutive equations has been developed and calibrated from creep experimental data, which can be used to predict the creep strain under age forming conditions perfectly. But the experimental results from stress relaxation ageing tests cannot be predicted with the established creep ageing constitutive equations, which shows that there is not a one-to-one correspondence between creep and stress relaxation, creep deformation is the most important but not the only reason for stress relaxation under age forming condition.

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