Plastics Final (Part 1) Flashcards
the resistance of the polymer melt to flow, representing the internal friction or stickiness of the material as it undergoes deformation during processing (31 cards)
Viscoelasticity
the resistance of the polymer melt to flow, representing the internal friction or stickiness of the material as it undergoes deformation during processin
Creep vs. Stress Relaxation
Creep: The gradual deformation of a material under constant stress over time.
-Stress Relaxation: The decrease in stress within a material under constant strain over time.
Creep Curves
Graphical representation showing how strain changes with time under constant stres
Specific Heat / Heat Capacity
The amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius.
Thermal Conductivity
The ability of a material to conduct heat
Coefficient of Thermal Expansion
The measure of how a material expands or contracts with a change in temperature, a homework assignment might involve calculations related to this property
Polymer Degradation Mechanisms
Swelling / Dissolution, and Chain Scission
Swelling / Dissolution
The absorption of a solvent causing the polymer to swell or dissolve
Chain Scission
Breakage of polymer chains, leading to a reduction in molecular weight
Testing Methods to Evaluate Degradation
Techniques used to assess the extent of degradation, such as spectroscopy or mechanical testing
Rheology
how polymers deform and flow under the influence of applied stress, encompassing factors such as viscosity, shear rate, and temperature.
Newtonian vs. Non-Newtonian Behavior
Newtonian fluids have constant viscosity, while non-Newtonian fluids exhibit variable viscosity under different shear rates
Shear Stress, Shear Rate, Viscosity
Parameters describing the behavior of materials under she
Viscosity vs. Shear Rate Curves
Graphical representation depicting how viscosity changes with shear rate
Melt Flow Rate Testing
A measure of a polymer’s flowability under specific temperature and pressure conditions
“Apparent” Rheological Properties
Properties observed under specific conditions, which may differ from the material’s true rheological behavior
Factors that Influence the Response
Variables affecting how a material responds to applied stress or deformation.
Fillers vs. Reinforcements
Distinction between materials added to enhance specific properties (fillers) and those added for strength (reinforcements)
Fibrous Reinforcement Issues
Challenges and considerations related to using fibrous materials to reinforce polymers.
Material Selection for an Application
Functional Requirements:
- Identifying the desired properties a material must possess for a specific application.
Base Resin Morphology / Properties
Understanding the inherent properties and structure of the base polymer.
Additive Packages for Application Specific Improvements / Protection
Selection of additives to enhance specific performance or protect against degradation
Iso-stress vs. Iso-strain Loading
Different loading conditions in composite materials where stress or strain is held constant
PMC
Polymer Matrix Composites
