Understanding Glass and Polymer Structures and Properties

Glass

A disordered, noncrystalline solid.

Amorphous Solid

A solid lacking long-range order (LRO).

Long-Range Order (LRO)

Order present in crystalline materials only.

Short-Range Order (SRO)

Order found in all solid materials.

SiO2

Silicon dioxide, a common glass-forming material.

Coordination Number

Number of nearest neighbors around an atom.

Silicon Coordination in SiO2

Silicon has a coordination number of 4.

Oxygen Coordination in SiO2

Oxygen has a coordination number of 2.

Radial Distribution Function

Measures probability of finding atoms at distances.

Pair Correlation Functions

Related to measurements of atomic arrangements.

Thermal Energy

Energy due to atomic vibrations above absolute zero.

Viscosity

Resistance of a liquid to flow.

Glass Formation

Process of transitioning from liquid to solid state.

Energy Barrier

Energy required for atoms to rearrange.

Tg (Glass Transition Temperature)

Temperature where viscosity significantly increases.

Fictive Temperature

Apparent Tg at faster cooling rates.

Refractive Index

Ratio of speed of light in vacuum to material.

Clausius-Mossotti Relationship

Links refractive index to electron density.

Molar Volume

Volume occupied by one mole of a substance.

Crystalline Structure

Ordered arrangement of atoms in solids.

Amorphous Structure

Disordered arrangement of atoms in solids.

X-ray Diffraction

Technique to analyze atomic structure of materials.

Fast vs. Slow Cooling

Cooling rates affect glass structure and properties.

Higher Density

Increases refractive index of materials.

Fictive Temperature

Temperature at which glass structure becomes stable.

Refractive Index

Measure of light speed reduction in a medium.

Quenching

Rapid cooling process affecting glass properties.

Modifiers

Elements that disrupt glass network structure.

Typical SiO2 Glass

Standard form of silicon dioxide used in glass.

Soda Lime Glass

Common glass type made with sodium and calcium.

Tg (Glass Transition Temperature)

Temperature where glass transitions to a more fluid state.

Thermal Conductivity

Ability of a material to conduct heat.

Viscosity

Resistance of a fluid to flow.

Monomers

Basic repeating units in polymer chains.

Molecular Weight

Weight of a molecule, affecting polymer properties.

Number Average Molecular Weight

Average molecular weight based on number of molecules.

Weight Average Molecular Weight

Average molecular weight weighted by mass of molecules.

Homopolymer

Polymer made from one type of monomer.

Copolymer

Polymer made from two or more different monomers.

Side Groups

Additional groups attached to polymer backbone.

Elastic Constant

Measure of a material's stiffness.

Chemical Resistance

Material's ability to withstand chemical dissolution.

Strength and Toughness

Material's ability to withstand stress and deformation.

Atomic Motion

Movement of atoms within a material.

Cs vs Na

Cesium has higher atomic number than sodium.

Backbone

Main structural component of a polymer chain.

Styrene Monomer

Rigid and bulky monomer affecting polymer properties.

Tg

Glass transition temperature indicating polymer rigidity.

Polar Side Group

Enhances intermolecular forces, increasing polymer strength.

Flexible Side Group

Reduces rigidity, allowing for higher Tg.

Tacticity

Arrangement of polymer chains affecting crystallization.

Atactic

Random arrangement of polymer chains, less dense.

Isotactic

Same side arrangement of polymer chains, more crystalline.

Syndiotactic

Alternating arrangement of polymer chains, enhances properties.

Polymer Architecture

Structure defining the arrangement of monomer units.

Grafted Polymer

Main chain differs from branches in composition.

Blend

Physical mixture of two different monomer chains.

Acrylonitrile Butadiene Styrene (ABS)

Example of a rubber-toughened thermoplastic polymer.

Covalent Cross-Linking

Chemical bonds linking polymer chains for strength.

Physical Cross-Linking

Non-covalent interactions between polymer chains.

Vulcanization

Process of cross-linking rubber to enhance properties.

Network Polymers

Polymers with interconnected chains for structural integrity.

Deborah Number

Ratio of relaxation time to observation time.

Viscoelastic Behavior

Time-dependent mechanical response of polymers.

Secondary Bonds

Non-covalent interactions affecting polymer strength.

Molecular Weight

Higher weight generally increases mechanical strength.

Mechanical Strength

Ability of a polymer to withstand applied forces.

Viscoelasticity

Material behavior combining liquid and solid properties.

Creep

Strain changes over time under constant stress.

Stress Relaxation

Stress decreases over time under constant strain.

Deborah Number

Dimensionless number indicating material's time dependence.

Polyvinyl Alcohol

A polymer used in making slime.

Boric Acid

Ionizes in solution, used in slime.

Glass Transition Temperature (Tg)

Temperature where polymer transitions from glassy to rubbery.

Thermosets

Polymers that cannot be remelted after curing.

Thermoplastics

Polymers that can be melted and reshaped.

Crystalline Polymers

Polymers with ordered molecular structure.

Hydrogels

Polymers that swell in water but can be cross-linked.

Spherulites

Spherical aggregates of crystallites in polymers.

Lamella

Folded regions of polymer chains in crystalline structures.

Crystallites

Small crystalline regions within a polymer.

Tacticity

Arrangement of side groups in polymer chains.

Isotactic

Polymer chains with all side groups on one side.

Syndiotactic

Polymer chains with alternating side group arrangements.

Elastic Modulus

Measure of a material's stiffness.

Melting Temperature

Temperature at which a solid becomes liquid.

Opacity

Degree to which a material prevents light transmission.

Chain Motion

Movement of polymer chains affecting material properties.

Cross-linking

Chemical bonds linking polymer chains, affecting properties.

Thermal Energy

Energy related to temperature affecting molecular motion.

Dye Segregation

Dye accumulates in amorphous polymer regions.

Vapor Barrier Properties

Higher crystallinity improves gas impermeability.

Spider Silk

Natural fiber with strong, crystalline structure.

Repeating Peptide Sequence

Forms hydrogen bonds in spider silk.

Frame Threads

Strong, highly crystalline silk threads.

Capture Threads

Less crystalline, more plasticized silk threads.

Optimal Tg

Glass transition temperature for specific environments.

Optimal Tm

Melting temperature for specific environments.

Semiconducting Polymers

Polymers with enhanced charge transport properties.

Conjugated Polymers

Polymers with alternating single and double bonds.