Introduction to Polymers: Lecture Series

<p>Tg and HDT are related but not directly proportional. (D)</p> Signup and view all the answers

<p>Plasticizers. (D)</p> Signup and view all the answers

<p>VST measures softening, while HDT measures structural deflection under load. (B)</p> Signup and view all the answers

<p>Adhesive wear. (B)</p> Signup and view all the answers

<p>Frictional heating wear. (D)</p> Signup and view all the answers

<p>A larger change in length for a given temperature change. (B)</p> Signup and view all the answers

<p>Dynamic Viscosity (η) (A)</p> Signup and view all the answers

<p>Zero-Shear Viscosity (η0) (D)</p> Signup and view all the answers

<p>Intrinsic Viscosity [η] and Molecular Weight (M) (B)</p> Signup and view all the answers

<p>Brookfield Viscometer (C)</p> Signup and view all the answers

<p>Capillary Viscometer (C)</p> Signup and view all the answers

<p>Ostwald Viscometer (C)</p> Signup and view all the answers

<p>The viscosity decreases with increasing shear rate. (D)</p> Signup and view all the answers

<p>Apparent Viscosity (ηapp) (D)</p> Signup and view all the answers

<p>Uniform shear rate distribution (C)</p> Signup and view all the answers

<p>Dynamic Mechanical Analysis (DMA) (D)</p> Signup and view all the answers

<p>The balance between elastic and viscous behavior (D)</p> Signup and view all the answers

<p>The material behaves more like a liquid (C)</p> Signup and view all the answers

<p>It marks the transition from liquid-like to solid-like behavior (D)</p> Signup and view all the answers

<p>It is applicable to all types of polymers (A)</p> Signup and view all the answers

<p>High G' and low G'' are both indicative of solid-like behavior. (C)</p> Signup and view all the answers

<p>It leads to non-uniform shear distribution. (D)</p> Signup and view all the answers

<p>Thermoplastics have weaker intermolecular forces, allowing them to melt and reshape without degradation. (A)</p> Signup and view all the answers

<p>Block copolymer (B)</p> Signup and view all the answers

<p>Branched polymers have a larger surface area, which increases the spacing between polymer chains. (D)</p> Signup and view all the answers

<p>Chain growth polymerization (C)</p> Signup and view all the answers

<p>Chains connected by covalent bonds forming a rigid, three-dimensional network (B)</p> Signup and view all the answers

<p>To improve the processability and performance of the polymer (D)</p> Signup and view all the answers

<p>Artificial heart valves (D)</p> Signup and view all the answers

<p>The high cost of polymer production compared to other materials (C)</p> Signup and view all the answers

<p>Tensile strength (C)</p> Signup and view all the answers

<p>Entanglements between polymer chains become more pronounced and restrict movement. (D)</p> Signup and view all the answers

<p>Higher crystallinity leads to a higher modulus due to the rigid structure of crystalline regions. (D)</p> Signup and view all the answers

<p>Thermoplastics exhibit significant deformation before breaking, often reported as stress at specific deformations. (B)</p> Signup and view all the answers

<p>Increased crosslinking increases the modulus by locking the chains in place. (C)</p> Signup and view all the answers

<p>Necking is a localized thinning of the material occurring after the yield point. (C)</p> Signup and view all the answers

<p>Bending tests are used to evaluate a material's resistance to forces that cause bending or flexing. (A)</p> Signup and view all the answers

<p>Ductile polymers deform significantly before breaking, while brittle polymers fracture with little deformation. (A)</p> Signup and view all the answers

Large molecules made from repeating monomers through polymerization.

The chemical process of linking monomers to form polymers.

Polymers that can be melted and reshaped, making them recyclable.

Polymers that cannot be melted and reformed; they decompose instead.

Polymers made from two or more different monomers.

Copolymers with monomers distributed randomly along the chain.

Copolymers where monomers are grouped in distinct segments.

The spatial arrangement of polymer chains affecting properties.

The degree of structural order in a polymer. Higher crystallinity results in increased stiffness due to rigid structures.

The process of linking polymer chains with bonds, increasing rigidity. High crosslinking can lead to thermoset materials.

Refers to how polymer chains respond to stress; low frequency allows organization, while high frequency increases stiffness due to entanglements.

The stress level at which a material begins permanent deformation, leading to plastic changes.

A phenomenon where a localized thinner region forms in a material after reaching its yield point under stress.

Ductile polymers stretch significantly before breaking, while brittle ones fracture with minimal deformation.

The resistance of a material to deformation; high modulus indicates high stiffness.

Evaluates material behavior under compression, measuring compressive modulus and strength.

Resistance to sliding between surfaces.

Loss of material as small particles detach due to surface adhesion.

Wear caused by excess heat leading to local melting and damage.

Transition temperature from solid to liquid for crystalline polymers.

Transition from glassy to rubbery state for amorphous polymers.

The highest temperature a polymer can withstand under load without significant deformation.

Temperature where a 1 mm² indenter penetrates a polymer sample by 1 mm under specific force.

The tendency of a polymer to expand when heated.

Measures the change in material length per degree of temperature change, represented by α.

Failure mode where materials undergo significant plastic deformation before fracturing.

Fracture with minimal deformation; occurs suddenly at stress concentrations.

Formation of microvoids in polymers under tensile stress, not a crack but may lead to failure.

Crack growth due to repeated cyclic loading, often below immediate failure loads.

Includes bond energy, material type, crosslinking, and crystallinity affecting expansion level.

Key considerations for choosing materials include strength, ductility, and resistance to fatigue.

Design features such as notches or sharp corners that can lead to failure; should be avoided.

Region where shear thinning occurs as polymer chains align.

Viscosity measured under an applied shear force.

Ratio of dynamic viscosity to density of a fluid.

Extrapolated viscosity at very low shear rates.

Calculated from complex modulus divided by angular frequency.

Extrapolated viscosity at different concentrations to zero concentration.

Instrument measuring kinematic viscosity based on gravity-driven flow.

Measures viscosity using a rotating spindle in controlled conditions.

A device using two cylinders to control shear rate for viscosity measurement.

A rheometer using a cone on a flat plate to maintain constant shear rate.

A rheometer consisting of two plates with adjustable gap to study suspensions.

Technique measuring elastic and viscous properties with oscillating stress.

Measures the elastic response of a material in oscillatory testing.

Measures the viscous response of a material in oscillatory testing.

The point where storage modulus equals loss modulus indicating a phase change.

Technique to extend measurement range by shifting curves on a frequency axis.