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Group 6 Presentation Chapter 7, 8, and 9. Gavin Kurey Kevin Archibeque David Barboza Cedric Turcotte Marcos Gonzales. Overview of Presentation:. Structure, General Properties, and Applications of: Polymers (Ch. 7) Ceramics, Graphite, and Diamonds (Ch. 8) Composite Materials (Ch. 9).

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Group 6 presentation chapter 7 8 and 9

Group 6 PresentationChapter 7, 8, and 9

Gavin Kurey

Kevin Archibeque

David Barboza

Cedric Turcotte

Marcos Gonzales


Overview of presentation

Overview of Presentation:

Structure, General Properties, and Applications of:

Polymers (Ch. 7)

Ceramics, Graphite, and Diamonds (Ch. 8)

Composite Materials (Ch. 9)

Pictures from Accelrys


Chapter 7 structure general properties and applications of polymers

Chapter 7Structure, General Properties, and Applications of Polymers

Background of Polymers

Characteristics of Polymers

The Structure of Polymers

Types of Plastics and Rubbers

Recycling Plastics


Background of polymers

Background of Polymers

Terminology:

Polymer – Poly meaning many and mer meaning unit.

Monomers – Basic building block of a polymer.

Macromolecules – extremely large collections of molecules to form one unit.

Plastics – a synonym for polymers.

Synthetic – manmade.


Background of polymers1

Background of Polymers

The word plastic comes from the Greek word plastikos, meaning capable of being molded and shaped.

The earliest polymers, such as cellulose, were made from natural organic materials from animals and vegetable products.


Background of polymers2

Background of Polymers

  • Bakelite, the earliest synthetic polymer, is made from phenolformaldehyde, a thermoset developed in 1906.


Background of polymers3

Background of Polymers

The development of modern polymer technology began in the 1920’s when raw materials necessary for making polymers were extracted from coal and petroleum products. Ethylene was the first example of such raw material.


Characteristics of polymers

Characteristics of Polymers

Plastics contain large molecules

Two common examples of how plastics can be shaped are:

Forming

Machine Casting





Characteristics of polymers4

Characteristics of Polymers

Advantages of using plastics:

Low Cost

Low Electrical and Thermal Conductivity

Low Density

High Strength-to-Weight Ratio

Resistance to Chemical Corrosion

Amount of Noise Reduction

Assortment of Colors and Transparencies

Ease of Manufacturing

Minimal Additional Surface Treatments

Forms of Availability Such As: Tubes, Films,

Sheets, Plates, Rods, etc.


Structures of polymers

Structures of Polymers

Definitions:

Molecular Weight Distribution (MWD), is the sum of the molecular weights of the mers in a chain

Degree of Polymerization (DP), is the size of the polymer chain

MWD and DP determines the tensile strength, impact strength, and viscosity of polymers.


Structures of polymers1

Structures of Polymers

An increase in MWD, increases:

Tensile Strength

Impact strength

Resistance to cracking

Viscosity

The larger DP, the larger:

Viscosity

Cost (because harder to shape)


Structures of polymers2

Structures of Polymers

Polymers are very large molecules compared to most other organic materials

They are long chain of molecules linked together by a process called polymerization.

There are two important types of Polymerization:

Condensation Polymerization

Addition Polymerization


Structures of polymers3

Structures of Polymers

Condensation Polymerization:

Known as Step-Growth or Step Reaction

Is the process in which polymers are produced by the formation of bonds between two types of reacting mers. In better terms, the polymer grows step-by-step until all of one reactant is consumed.

Example: Water is condensed out to make plastic.


Structures of polymers4

Structures of Polymers

Addition Polymerization:

Known as chain-growth or chain-reaction

Much faster than condensation method

Is the process in which the chain-growth takes place without reactant by-products such as water

An initiator is added to the reaction to open the double bond between the two carbon atoms


Structures of polymers5

Structures of Polymers

  • Examples of the basic building blocks for plastics:


Structures of polymers6

Structures of Polymers

Linear Polymers

Sequential structures

Branched Polymers

Increase resistance to deformation and stress cracking.

Cross Linked Polymers

(Thermosets) have a major influence in polymers. Imparting hardness, strength, stiffness, brittleness, and better dimensional stability.

Networked Polymers

(highly cross linked), have a higher strength when exposed to high energy radiation, UV light, x-rays, or electron beams.


Structures of polymers7

Structures of Polymers

Copolymers contain two types of polymers

Ex: Styrene-butadiene, used in making tires

Terpolymers contains three types of polymers

Ex: Acrylonitrile-butadiene-styrene, used to make helmets


Structures of polymers8

Structures of Polymers

Amorphous, the polymer chains exist without order.

Crystallites, the regions arrange themselves in an orderly manner.


Structures of polymers9

Structures of Polymers

As Crystallinity increases polymers become:

Stiffer

Harder

Less ductile

More dense

Less rubbery

More resistant

to solvents and heat.


Thermoplastics

Thermoplastics

Polymers that can undergo external shaping forces and return to their original state

Ex: Acrylics, Nylons, Polyethylenes


Thermoplastics1

Thermoplastics

Characteristics and Effects on Thermoplastics:

Effects of Temperature

Rate of Deformation

Orientation

Creep/Stress Relaxation

Crazing

Water Absorption

Thermal and Electrical Properties


Effects of temperature

Effects of Temperature

Glass-Transition Temperature (Tg)

Above the Tg, the thermoplastic gradually softens and eventually turns into a viscous fluid.

Repeated heat-cycling causes thermal aging or degredation.

Effects of Temp. on thermoplastics is similar to that of metals, (for increased T, Increased toughness, strength/modulus of elasticity decreases)


Rate of deformation

Rate of Deformation

Thermoplastics can undergo large uniform deformation in tension before fracture.

This characteristic allows for thermoforming.

Complex shapes can be made, like bottles, meat trays, etc.


Orientation

Orientation

Under deformation, the molecules within thermoplastics align themselves in unison with the deformation.

This is called Orientation.

The specimen becomes anistropic

Important for enhancing strength and toughness properties


Creep stress relaxation

Creep/Stress Relaxation

Most thermoplastics are susceptible to Creeping and/or stress relaxation

This can even occur at room temperature!


Crazing

Crazing

Localized, deformed areas that are wedge-shaped that occur under stress

Sometimes appearing to be cracks, crazes are usually comprised of voids (50%).

Caused by enviroment stress or other external forces, like solvents.

Stress whitening


Water absorption

Water Absorption

Polymers absorb water

Water acts as a plasticizing agent

Lubrication

Tg, elastic modulus, and yeild stress are all lowered when water is absorbed

Dimensional changes


Thermal electrical properties

Thermal/Electrical Properties

low thermal/electrical conductivity and a high coefficient of thermal expansion

Good as insulators and packaging for electronics

Doping

Electrically conducting Polymers (metal powders, iodides, salts)

Thermally conducting Polymers (nonmetallic, conductive particles;100x more conductive)


Thermosets

Thermosets

When long chain molecules in a polymer become one giant molecule with strong covalent bonds and is from then on permanently set.

The curing reaction of a thermoset is irreversible, unlike thermoplastics

No set Tg value, rate of deformation, or response to temperature.


Additives in plastic

Additives in Plastic

Plasticizers

Carbon Black

Fillers

Colorants

Flame Retardants

Lubricants


Plasticizers

Plasticizers

Adds Flexibility

Adds Softness

Achieved by reducing secondary bond strength

Most common use of a plasticizer is found in PVC (Polyvinylchloride)


Carbon black

Carbon Black

Soot

Compounded into plastics and rubbers

Protects against Oxidation and Ultraviolet Radiation


Fillers

Fillers

Reduces overall cost of a polymer

May improve hardness, toughness, stiffness, abrasion resistance, etc

Common fillers include: Saw Dust, silica flour, clay, mica, talc, asbestos, etc


Colorants

Colorants

Organic or Inorganic

Dyes(organic)

Pigments(inorganic)

Colorant selection depends on service temperature and light exposure.

Pigments have a higher tolerance to temp and light.


Flame retardants

Flame Retardants

Additives to reduce the flammability of a polymer

Common additives include phosphorus, chlorine, and boron

Cross-linking reduces flammability as well


Lubricants

Lubricants

Added to reduce friction during processing.

Typical lubricants are: Linseed oil, mineral oil, waxes, metallic soaps, etc

Very important to keep thin polymer sheets from sticking to each other



Biodegradable plastics

Biodegradable Plastics

Biodegrability - microbial species can decompose the object over time

Three different biodegradable plastics have been developed thus far: Starch-based, Lactic-based, and Fermented Sugar Systems.


Recycling

Recycling

Thermoplastics can be recycled by melting them down and reshaping them into new products

Recycling symbols/numbers

  • PETE (polyethylene)

  • HDPE (high density polyethylene)

  • V (vinyl)

  • LDPE (low density polyethylene)

  • PP (polypropylene)

  • PS (polystyrene)

  • Other


Elastomers

Elastomers

Also known as Rubber

Ability to undergo large elastic deformations without rupture

Highly kinked structure

Stretch under load, but return to original shape without load

Vulcanization (cross-linking w/ sulfur)

Types of elastomers: Natural Rubber, Synthetic Rubber, Silicones, Polyurethane


Ceramics

Ceramics

Definition: Ceramics are compounds of metallic and non-metallic elements

Two Major Categories:

Traditional such as whiteware, tiles, bricks, and pottery.

Industrial uses:

turbines, cutting tools, and aerospace applications.


Major types of oxide ceramics

Major types of oxide ceramics

  • Alumina:

  • Used both in its raw form or as an ingredient blended with other ceramics.

  • Are the most commonly used ceramic material

  • Used as an abrasive such as grinding wheels or sandpaper.

  • Affordable compared to other ceramics.


Major types of oxide ceramics1

Major types of oxide ceramics

  • Zirconia:

  • Possesses high toughness and strength, resistance to thermal shock, wear, corrosion and low thermal conductivity.

  • Excellent or good for high heat applications such as dies for hot extrusions, aerospace coatings.

  • Definitions:

  • Thermal Shock-Refers to the development of cracks after a single thermal cycle.

  • Thermal conductivity- Rate at which heat flows within and through a material. Ionically or covalently bonded have poor conductivity


Carbides

  • Tungsten Carbide

  • Made from tungsten-carbide particles with cobalt as a binder

  • The quantity of binder used has a major influence on the attributes of the final product.

  • Cobalt increases toughness, but hardness, strength, and wear resistance decreases

Carbides

  • Titanium Carbide

  • Not as tough as Tungsten Carbide.

  • Uses nickel and molybdenum as a binder.

  • Most often used as cutting tools.

  • Silicon carbide

  • Low friction coefficient while still retaining its strength at elevated temperatures.


Nitrides

Nitrides

  • Silicon Nitride

  • Used in high temperature applications since it possesses a high resistance to thermal shock and creep.

  • Definition

  • Creep is the permanent elongation of a component under a static load over a long period of time.

Cubic Boron Nitride

It is the second hardest known substance.

Synthetically made in a manner similar to synthetic diamonds.

It is not found in nature.

It is often used in cutting tools and abrasive wheels.


Nitrides1

Nitrides

  • Titanium Nitride (TiN)

  • Is gold in color and is very widely used as a coating for cutting tools. Drill bits, end mills, etc.


Sialon and cermets

Sialon and Cermets

  • Sialon

  • It is a combination of Silicon, Aluminum, Oxygen, and Nitrogen.

  • It is more thermal-shock resistant and has a higher strength than Silicon Nitride.

  • It sees use as a machine cutting tool.

  • Cermets

  • It is a combination of Ceramics phase bonded with a Metallic phase.

  • They marry the high temperature oxidation resistance of ceramics with the ductility, toughness, and thermal-shock of metals.

  • Introduced in the 1960’s.

  • Often used in machining tools.


Silica and nanoceramics

  • Silica

  • Found in nature silica can have different crystal structures or is called a polymorphic material.

  • The most common form found is quartz.

  • The cubic structure is found in the ceramic refractory bricks used in high temperature furnaces.

Silica and Nanoceramics

  • Nanoceramics

  • By reducing the size of the particles, nanoceramics are formed.

  • They consist of atomic clusters containing a few thousand atoms.

  • They are ductile at much lower temperatures than conventional ceramics

  • Stronger and easier to machine with less flaws.

  • Found in the automotive industry for valves, turbocharger rotors, and cylinder linings.


Bioceramics

Bioceramics

Because of their strength and inertness the most common uses include replacement for human joints, prosthetic devices and teeth crowns.


Advantages disadvantages

Advantages/Disadvantages

  • Advantages

  • Ceramics tend to be very hard, abrasion resistant, able to operate in high temperatures, and resistant to corrosive chemicals.

  • Disadvantages

  • Expensive to manufacture and machine

  • Due to the hardness and the abrasive nature of many ceramics diamond tools are required to machine, which is very time consuming and expensive.

  • Tend to be brittle and do not take impact loads very well.

  • Not as tough as metal


Section 8 4 8 7

Section 8.4 - 8.7

Types of Glasses

Properties of Glasses

Glass Ceramics

Types of Graphite

Diamond


Glass terminology

Glass Terminology

Terminology:

Glass- an amorphous solid with the structure of a liquid.

Glass is an inorganic product of fusion that has been supercooled to a rigid condition without crystallizing.

Supercooled- the cooling of a liquid at a rate too high to allow crystals to form.


Types of glasses

Types of Glasses

Soda-lime glass- The most common type of commercial glass.

Lead-alkali glass-

Borosilicate glass

Aluminosilicate glass

96%-silica glass

Fused silica glass


Types of glasses1

Types of Glasses

Soda-lime glass


Types of glasses2

Types of Glasses

Lead-alkali glass


Types of glasses3

Types of Glasses

Borosilicate glass


Types of glasses4

Types of Glasses

Aluminosilicate glass


Types of glasses5

Types of Glasses

96%-silica glass


Types of glasses6

Types of Glasses

Fused silica glass


Characteristics of glass

Characteristics of Glass

Glass is categorizied by its:

Density

Strength

Resistance to thermal shock

Electrical resistivity

Hot workability

Heat Treatability

Chemical Resistance

Impact-abrasion resistance

Ultraviolet-light transmission


Glass classifications

Glass Classifications

Colored

Opaque (White or Translucent)

Photochromatic (Darkens with light exposure)

Photosensitive (Changing from clear to opaque

Fibrous (Constructed of long fibers)

Foam or cellular (containing bubbles)

Hard or Soft (Thermal hardness)

Elasticity (Modulus of elasticity 55 to 90 GPa)

Scratch Resistance (350 to 500 HK)


Glass ceramics

Glass Ceramics

Glass Ceramics have a higher crystalline component than that of glass.

This increase in crystalline is due to the Devitrification of the glass.

Devitrification- is the recrystallization of glass which occurs due to the heat treating of the glass after the desired shape is constructed.

Glass Ceramics have a hardness of 520 to

650 HK, which is significantly larger than the hardness of typical glass (350 to 500 HK).


Characteristics of glass ceramics

Characteristics of Glass Ceramics

High resistance to thermal-shock, due to their non-zero coefficient of thermal expansion

Extremely strong due to the absence of porosity; which is typically found in traditional ceramics

Glass ceramics are commonly used for cookware, heat exchangers in gas turbines engines, housing for radar antennas, and other electrical applications.


Background on graphite

Background on Graphite

Graphite- a crystalline form of carbon having a layered structure with basal planes or sheet of close-packed carbon atoms.

Lampblack (black soot) is an amorphous graphite that is used as a pigment


Characteristics of graphite

Characteristics of Graphite

The strength and stiffness of graphite increases with temperature

High electrical and thermal conductivity

Good resistance to thermal shock and high temperature

High resistance to chemicals


Types of graphite and uses

Types of Graphite and Uses

Graphite Fibers- used to reinforce plastics

Carbon and Graphite Foams- used for core material for aircraft and ship interior panels, structural insulation, sound absorption panels, lithium-ion batteries, and for fire and thermal protection

Buckyballs- solid lubricant particles that are made from lampblack (black soot)

Nanotubes- used as a natural building material for new microelectromechanical systems


Types of glasses7

Types of Glasses

BuckyballsNanotubes


Diamonds

Diamonds

Diamond- a principal form of carbon with a covalently bonded structure

Hardest substance known (7000 to 8000 HK)

Very brittle, starts to decompose in air at 700oC


Chapter 9 composite materials

Chapter 9: Composite Materials


Definition

Definition:

A composite material is a combination of two or more chemically distinct and insoluble phases with recognizable interface, in such manner that its properties and structural performance are superior to those of the constituents acting independently.

(Book definition p.238)


Quick examples every day use to space ship applications

Quick examples:Every day use to space ship applications…

First engineering application 1907:

acid-resistant tank (Phenolic resin with asbestos fibers)

Steel-wire reinforced tires;

Snow boards / skis;

Tennis raquets;

Protective gear;


Quick examples

Quick examples:

Reinforced concrete;

2 x more resistant (compression)


Quick examples1

Quick examples:

Sailboard

(see p.249);


Quick examples2

Quick examples:

Fiberglass;


Quick examples3

Quick examples:

Brake pads / rotors;


Quick examples4

Quick examples:

High speed

fan blades;


Quick examples5

Quick examples:

High performance racing body parts;


Structure of reinforced plastics composite

Structureof reinforced plastics (composite)

Don’t get confused by the PLASTIC appellation.

Reinforced plastics: also know as polymer-matrix composites&fiber-reinforced plastics.

Two phases:

1 . Fibers (discontinuous)

2. Matrix (continuous)


Fibers

Fibers:

Known as a slender, elongated, threadlike object or structure


Fibers continued

Fibers:(continued)

They combine high strength and high stiffness.

Variety

Graphite – Glass – Boron – Polymer;

Others (boron carbide, steel, aluminium oxide, etc.)

When more then two fibers are used, the composite is called a hybrid.

Percentage of fibers in reinforced plastics varies from 10% to 60%. Anything higher then 65% usually result in lower structural properties.

Fibers are sometimes treated with a coating to increase bonding strength between fiber and matrix.


Fibers continued1

Fibers:(continued)

Cross-section usually less then 0.0004 in. (hair =0.001in)

Sensible to defects

Short & long fibers:In a given type of fiber, if the mechanical properties improve as a result of increasing the average fiber length, then it is call a short fiber. Otherwise it’s a long fiber.

Continuous fibers: Offers a better control on composite’s reaction. Generally use for oriented forces or for increased properties.


Matrix

Matrix

Known as the bonding substance.


Matrix continued

Matrix (continued)

Tough and generally chemically inert.

Functions:

Support the fibers in place and transfer the stress to them while they carry most of the load;

Protect the fibers against physical damage and the environment;

Reduce the propagation of cracks in the composite by virtue of the greater ductility and toughness of the plastic matrix.


Matrix continued1

Matrix (continued)

Thermosets: epoxies (80%) – polyester - silicon

Thermoplastics:Polyetheretherketone; thougher then thermosets, but lower temperature resistance;

Metals: aluminium – magnesium - titanium

Ceramics: silicon carbide/nitride – aluminium oxide - mullite


Properties

Properties

The mechanical and physical properties of reinforced plastics depend on type, shape, and orientation of the reinforcing material, the length of the fibers, and the volume fraction of the reinforcing material.

Short fibers are less effective than long fibers.

Bond strength between fibers and matrix is a critical to avoid fiber pullout and delamination, and to maintain good load transmission.


Orientation of fibers

Orientation of fibers

Random(5-25%)

(mostly short or long fibers, not continuous)

Orthogonal (20-40%) Unidirectional (100%)






References for chapter 7

References for Chapter 7

http://www.accelrys.com

http://www.edmar-co.com

http://www.mahjongmuseum.com

http://www.4to40.com

http://www.seismo.unr.edu

http://www.silverhook.co.uk

http://www.nyu.edu

http://www.euroarms.net

http://alfiesantiques.com

http://depts.washington.edu

http://www.camposgroup.com

http://www.texwipe.com

http://archives.cnn.com

http://www.sandretto.it

http://weather.wkowtv.com/ images/


References for chapter 8

  • www.performancecoatings.com

  • www.ortechceramics.com

  • www.ceramicindustry.com

  • www.bearingworks.com

  • www.tribology.com

  • www.fujikin.com

  • www.ornl.gov

References For Chapter 8


References
References

  • HTTP://WWW.MS.ORNL.GOV/RESEARCHGROUPS/CMT/FOAMS/FOAMS.HTM

  • http://handle.tamu.edu/1969.1/55

  • http://uk.dk.com/static/cs/uk/11/features/miller/images/aa_104_7_HAMG220304.jpg

  • http://www.pilkington.com/resources/floatstructure.jpg

  • http://www.beadmuseumdc.org/beadimages/bubble.jpg

  • http://www.pelletlab.com/images/1870.jpg


Reference list
Reference List

  • http://www.element-collection.com

  • http://www.ecplaza.net/tradeleads/seller/3415816/fused_silica_tube.html#none

  • www.dupont.com/safetyglass/ lgn/stories/2906.html

  • fireartstudio.ca/ WarmGlass.htm

  • www.ill.fr/dif/ 3D-crystals/bonding.htmlhttp://www.hofstra.edu/Academics/HCLAS/Chemistry/CHM_faculty_nirode.cfm

  • www.npacorp.com/ products/vitrolite.html


References1

References

Book ‘Des Materiaux’, Jean-Paul Baïlon, Edition Polytechnique.

http://hypertextbook.com/facts/1999/BrianLey.shtml


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