Molecular Confinement Accelerates Deformation of Entangled Polymers During Squeeze Flow

Science ◽  
2008 ◽  
Vol 322 (5902) ◽  
pp. 720-724 ◽  
Author(s):  
H. D. Rowland ◽  
W. P. King ◽  
J. B. Pethica ◽  
G. L. W. Cross
Keyword(s):  
Squeeze Flow ◽  
Entangled Polymers ◽  
Molecular Confinement

scholarly journals Static ultrasonic welding of carbon fibre unidirectional thermoplastic materials and the influence of heat generation and heat transfer

2021 ◽  
pp. 002199832097681
Author(s):  
F Köhler ◽  
IF Villegas ◽  
C Dransfeld ◽  
A Herrmann
Keyword(s):  
Cross Sections ◽  
Weld Line ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Thermoplastic Composites ◽  
Squeeze Flow ◽  
Anisotropic Flow ◽  
Lap Shear ◽  
Anisotropic Thermal Conductivity ◽  
Edge Defects

Ultrasonic welding is a promising technology to join fibre-reinforced thermoplastic composites. While current studies are mostly limited to fabric materials the applicability to unidirectional materials, as found in aerospace structures, would offer opportunities for joining primary aircraft structures. However, due to the highly anisotropic flow of a molten unidirectional ply undesired squeeze flow phenomena can occur at the edges of the weld overlap. This paper investigates how the fibre orientation in the plies adjacent to the weld line influences the welding process and the appearance of edge defects. Ultrasonic welding experiments with different layups and energy director configurations were carried out while monitoring temperatures at different locations inside and outside the weld overlap. The joints were characterized by single lap shear tests, analysis of corresponding fracture surfaces and microscopic cross-sections. Results showed that the anisotropic flow and the anisotropic thermal conductivity of the plies adjacent to the weld line have a distinct effect on the appearance and location of edge defects. By using energy directors that cover only part of the weld overlap area a new approach was developed to mitigate edge defects caused by the highly directional properties of the unidirectional plies.

Flow-Induced Orientation and Stretching of Entangled Polymers in the Framework of Nonequilibrium Thermodynamics

2016 ◽  
Vol 49 (8) ◽  
pp. 3161-3173 ◽  
Author(s):  
Pavlos S. Stephanou ◽  
Ioanna Ch. Tsimouri ◽  
Vlasis G. Mavrantzas
Keyword(s):  
Nonequilibrium Thermodynamics ◽  
Entangled Polymers

Rational Design of Novel Materials From Polymer Microrheology

2010 ◽  
Author(s):  
Rodrigo E. Teixeira ◽  
Richard S. Graham
Keyword(s):  
Rational Design ◽  
Molecular Level ◽  
Pressure Vessels ◽  
Novel Materials ◽  
Entangled Polymers ◽  
Stochastic Fluctuations ◽  
Safety Margins ◽  
Polymer Liquids ◽  
Entangled Polymer ◽  
High Degree

The visco-elastic properties of entangled polymer liquids arise from molecular-scale topological interactions and stochastic fluctuations under flow. Here, the evolutions of individual entangled polymers were observed in rheologically relevant shear flow histories. We uncover a high degree of molecular individualism and broad conformational distributions resulting from incessant stretch-collapse cycles. The data and insights of the present study may lead to improved molecular-level models and constitutive equations. These tools, in turn, may enable the rational design of novel materials with properties tailored to accomplish specific tasks such as high-pressure vessels and piping with greater safety margins and cost-effectiveness.

scholarly journals Modelling of pastes as viscous soils – Lubricated squeeze flow

2018 ◽  
Vol 323 ◽  
pp. 250-268 ◽  
Author(s):  
M.J. Patel ◽  
S. Blackburn ◽  
D.I. Wilson
Keyword(s):  
Squeeze Flow

Squeeze flow theory and applications to rheometry: A review

2005 ◽  
Vol 132 (1-3) ◽  
pp. 1-27 ◽  
Author(s):  
Jan Engmann ◽  
Colin Servais ◽  
Adam S. Burbidge
Keyword(s):  
Flow Theory ◽  
Squeeze Flow

Squeeze flow coupled with dynamic pressure mapping for the rheological evaluation of cement-based mortars

2018 ◽  
Vol 92 ◽  
pp. 18-35 ◽  
Author(s):  
Franco A. Grandes ◽  
Victor K. Sakano ◽  
Andressa C.A. Rego ◽  
Fábio A. Cardoso ◽  
Rafael G. Pileggi
Keyword(s):  
Dynamic Pressure ◽  
Squeeze Flow ◽  
Pressure Mapping
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