Quiz Study 1-8 Flashcards
On the basis of ionic charge and ionic radii, predict the crystal structure of CsI
Find the cation-anion ratio to find the coordination number.
Describe why most ceramic materials are brittle and show no plastic deformation.
In ceramics there is resistance to sliding and sliding is plastic deformation. Therefore, no plastic deformation.
Describe the difference in specific volume change with temperature between amorphous glasses and crystalline ceramics
Crystalline ceramics has an abrupt change in specific volume when T changes. Amorphous has a gradual change in viscosity.
Describe the benefit of adding soda and lime in terms of glass forming
Working range is improved and can work on glass @ lower T.
Describe the process and strengthening mechanism of tempered glass
Heat above transition T & below softening point followed by a controlled cool down. Compression is applied to suppress cracks.
Briefly describe the difference in the function of water in hydroplasticity and cementation.
Water molecules fit in between layered sheets and reduces degree of Van der Waals allowing for particles to move past one another. Cementation, water performs chemical bonding by hydration and not drying.
Describe the process of polymerization.
A chain of polymers is made. A reaction between a monomer & a free radical. This propagates by adding new monomers.
Describe the states and property of polymer vs molecular weight relationship.
A high molecular weight increases stretchability, impact resistance, chemical resistance, & viscosity.
Describe how the molecular chain of polymers can be bent, coiled, and kinked in terms of
bonding of backbone carbon atoms (C-C).
As long as the angle between the previous C atom. In tetrahedral shape and not in a straight chain and the atoms are relatively free to rotate around a single C-C bond.
Describe four molecular structures of polymers
Linear (Spaghetti), Branched (similar to linear w/ branches), cross linked (additives), Network (Reinforced Cross link)
Describe isotactic configuration, syndiotactic configuration, atactic configuration of polymers.
Isotactic-R groups are in same side of chain,
Syndiotactic- R groups alternate on side of chains
Atactic- R groups are random
When comparing crystalline polymers and amorphous polymers, which one has higher
density?
Amorphous are less packed than crystalline.
Describe three typical stress-strain curves of polymers and their microstructural changes during deformation
Brittle- Some gradual elastic deformation followed by a sudden fracture.
Plastic- Elastic deformation followed by plastic deformation.
Elastometer- Large elastic strain @ low stress
Describe the difference between thermoplastic and thermoset polymers.
Thermoplastic- soften when heated & hardened when cold can be repeated.
Thermosetting- Will become permanently deformed and does not soften when heated.
Describe two types of polymerization processes.
Addition- When you add monomer units to form a macro-molecule
Condensation- Inter-molecular chemical reactions that may involve more than one monomer species.
Describe the difference between fillers and plasticizers in terms of their functions to the mechanical properties in the polymers.
fillers- added to improve flexibility, ductility, toughness, stiffness.
Plasticizers- transforms from brittle to ductile.
Describe matrix and dispersed phases in composite materials.
matrix- transferred stress to dispersed phases and protects from environment.
Dispersed- Discontinuous with different sized particles, wires, & meshes.
Describe the critical length of fibers in fiber-reinforced composites.
Minimal length so that the entire load is transferred from matrix to fiber
Describe the mechanical properties (stress-strain curve and elastic modulus) of
continuous and aligned fiber composites in longitudinal loading conditions.
fibers stretch elastically and tensile strength of fiber is higher than the yield strength of the matrix.
Describe three different common types of polymer-matrix composites.
glass fiber, carbon fiber, and aramid fiber
Describe two typical types of structural composites.
Sandwich panel and Laminate Composite.
Ceramic materials are mostly compounds consisting of metallic and nonmetallic
elements
True
Ceramic materials have high hardness and high toughness
False
Hydration is a process used in the forming of ceramic clays
False
Soda-lime classes are easier to fabricate than pure silica (fused silica).
True
The density of crystalline polymers is the same as that of amorphous polymers
False
A chemical reaction between two or more monomer species, producing byproducts such
as water, occurs in condensation polymerization.
True
