Polymer Microlayer Composites

1991 ◽  
Vol 255 ◽  
Author(s):  
A. Hiltner ◽  
K. Sung ◽  
E. Shin ◽  
S. Bazhenov ◽  
J. Im ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Fatigue Properties ◽  
Irreversible Processes ◽  
Dramatic Improvement ◽  
Entire System ◽  
Usual Manner ◽  
Cooperative Process ◽  
Deformation Processes ◽  
Ductile Component ◽  
Primary Variable

AbstractContinuous microlayer composites of polycarbonate (PC), a ductile glassy polymer, and styrene-acrylonitrile copolymer (SAN), a glassy relatively brittle polymer, were discussed. Microlayered systems composed of 49 to 776 continuous layers, in which the primary variable was the variation in thickness of the continuous layers between 30 and 2μm, were emphasized. The bulk properties of these microlayered composites showed a dramatic improvement in the toughness or ductility and in the fatigue properties as the layer thickness decreased. Investigation of the irreversible deformation processes revealed that when the layers were thicker (30μm, 49 layers) the SAN layers crazed and the PC shear banded in the usual manner. Subsequently the composite system fractured in a relatively brittle manner due to the development of large voids in the SAN layers. When the layer thickness was reduced to 2μm (776 layers) the entire system behaved in a ductile manner and both the PC and SAN shear banded due to a new cooperative process. This was analyzed by considering the micromechanics of these irreversible processes at the PC-SAN interface. As a result of this work, it is expected that ultra-thin layered structures of other alternating composite systems will reveal synergistic properties if the interfacial properties are designed so that the ductile component will dominate the yield and failure characteristics of the entire system.

scholarly journals Scratching Cu|Au Nanolaminates

Lubricants ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 44 ◽  
Author(s):  
Adrien Gola ◽  
Lars Pastewka
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Layer Thickness ◽  
Wear Track ◽  
Complex Deformation ◽  
Normal Forces ◽  
Deformation Processes ◽  
Dynamics Simulations

We used molecular dynamics simulations to study the scratching of Cu|Au nanolaminates of 5 nm layer thickness with a nanoscale indenter of 15 nm radius at normal forces between 0.5 μ N and 2 μ N. Our simulations show that Au layers wear quickly while Cu layers are more resistant to wear. Plowing was accompanied by the roughening of the Cu|Au heterointerface that lead to the folding of the nanolaminate structure at the edge of the wear track. Our explorative simulations hint at the complex deformation processes occurring in nanolaminates under tribological load.

scholarly journals Effect of Cr Electroplating Layer Thickness on the Tensile and High Cycle Fatigue Properties of AISI 1045 Steel

2019 ◽  
Vol 57 (3) ◽  
pp. 138-145 ◽  
Author(s):  
Gi-Su Ham ◽  
Yeon-Ji Kang ◽  
Hyung-Jun Kim ◽  
Sang-Hoon Yoon ◽  
Kee-Ahn Lee
Keyword(s):  
Layer Thickness ◽  
High Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
1045 Steel

scholarly journals Effect of Temperature on Xylanase II from Trichoderma reesei QM 9414: A Calorimetric, Catalytic, and Conformational Study

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Gloria López ◽  
Pilar Estrada
Keyword(s):  
Trichoderma Reesei ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Effect Of Temperature ◽  
Irreversible Processes ◽  
Inactivation Kinetics ◽  
Scanning Calorimetry ◽  
Fluorescence Emission Spectra ◽  
State Process ◽  
Cooperative Process

The secondary structure of xylanase II from Trichoderma reesei is lost in an apparent irreversible cooperative process as temperature is increased with a midpoint transition of 58.8 ± 0.1°C. The shift of the spectral centre of mass above 50°C is also apparently cooperative with midpoint transition of 56.3 ± 0.2°C, but the existence of two isofluorescent points in the fluorescence emission spectra suggests a non-two-state process. Further corroboration comes from differential scanning calorimetry experiments. At protein concentrations ≤0.56 mg·mL−1 the calorimetric transition is reversible and the data were fitted to a non-two-state model and deconvoluted into six transitions, whereas at concentrations greater than 0.56 mg·mL−1 the calorimetric transition is irreversible with an exothermic contribution to the thermogram. The apparent Tm increased linearly with the scan rate according to first order inactivation kinetics. The effect of additives on the calorimetric transition of xylanase is dependent on their nature. The addition of sorbitol transforms reversible transitions into irreversible transitions while stabilizing the protein as the apparent Tm increases linearly with sorbitol concentration. d-Glucono-1,5-lactone, a noncompetitive inhibitor in xylanase kinetics, and soluble xylan change irreversible processes into reversible processes at high protein concentration.

scholarly journals Influence of layer thickness and post-process treatments on the fatigue properties of CoCr scaffolds produced by laser powder bed fusion

2018 ◽  
Vol 23 ◽  
pp. 498-504 ◽  
Author(s):  
Antonio Cutolo ◽  
Bram Neirinck ◽  
Karel Lietaert ◽  
Charlotte de Formanoir ◽  
Brecht Van Hooreweder
Keyword(s):  
Layer Thickness ◽  
Fatigue Properties ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Post Process
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