This document discusses polymerization reactions and polymer classification. It begins by defining monomers and polymers, and explaining that polymerization is the chemical reaction where monomers join together via covalent bonds to form polymers. Polymers are classified as homopolymers, copolymers, or by their chain structure. The two main types of polymerization reactions are step-growth and chain-growth polymerization. Step-growth includes condensation polymerization while chain-growth includes addition polymerization. The document provides examples of common polymers formed by different reaction types and ends by discussing applications of polymeric materials.
The presentation gives a brief idea about polymers,its definition,types of polymers,common examples of polymers,polymerization and its types,polymer processing and applications of polymers.
polymerization is a process of bonding monomer, or "single units" together through a variety of reaction mechanisms to form longer chains named Polymer.
I hope You all like it. I hope It is very beneficial for you all. I really thought that you all get enough knowledge from this presentation. This presentation is about materials and their classifications. After you read this presentation you knowledge is not as before.
The presentation gives a brief idea about polymers,its definition,types of polymers,common examples of polymers,polymerization and its types,polymer processing and applications of polymers.
polymerization is a process of bonding monomer, or "single units" together through a variety of reaction mechanisms to form longer chains named Polymer.
I hope You all like it. I hope It is very beneficial for you all. I really thought that you all get enough knowledge from this presentation. This presentation is about materials and their classifications. After you read this presentation you knowledge is not as before.
Polymers play a very important role in human life. Our body is made of lot of polymers, e.g. Proteins, enzymes, etc. Other naturally occurring polymers like wood, rubber, leather and silk are have wide application. Now a day synthetic polymer like useful plastics, rubbers and fiber materials are synthesized. presentation includes introduction classification and preparation methods. Polymers play a very important role in human life. Our body is made of lot of polymers, e.g. Proteins, enzymes, etc. Other naturally occurring polymers like wood, rubber, leather and silk are have wide application. Now a day synthetic polymer like useful plastics, rubbers and fiber materials are synthesized. Leo Baekeland patented the first totally synthetic polymer called Bakelite (1910). Bakelite is a versatile, durable material prepared from low-cost materials phenol and formaldehyde and was the most important synthetic polymer material. In the 1920s Hermann Staudinger showed that polymers were high-molecular-weight compounds held together by normal covalent bonds.
The suffix in polymer ‘mer’ is originated from Greek word meros – which means part. The word polymer is thus coined to mean material consisting of many parts or mers. A macromolecule having high molecular mass (103-107u) and generally not a well-defined structure or molecular weight. The macromolecules formed by joining of repeating structural units on a large scale. The repeating structural units are simple and reactive molecules linked to each other by covalent bonds. This process of formation of polymers from respective monomers is called polymerization. Most of the polymers are basically organic compounds, however they can be inorganic (e.g. silicones based on Si-O network).
Polymer science revolves around the study of macromolecules known as polymers, which are formed by linking together repeating units called monomers. Understanding the relationship between polymers and monomers is fundamental to grasping the diverse properties and applications of these materials.
Additionally, we'll delve into the nomenclature of polymers, which involves the systematic naming conventions used to describe their structure and composition. Clear and standardized nomenclature ensures effective communication within the scientific community and facilitates the classification of polymers based on their chemical structure, properties, and applications.
Methods of polymerisation It is also called as Zeigler – Natta polymerisation.
Zeigler (1953) and Natta (1955) discovered that in the presence of a combination of transition metal halides like TCl4, ZnBr3 etc, with an organometallic compound like triethyl-aluminium or trimethyl-aluminium, stereospecific polymerisation can be carried out.
Combination of metal halides and organometallic compounds are called Zeigler Natta catalyst.
Synthetic polymers - a content written by Dr.Lali Thomas Kotturan about man ...lalikotturan
A polymer is a giant molecule made from small identical repeating molecules called monomers joined together by covalent bonds. The process of interlinking the monomers to form a polymer is called polymerization. The Classification of Polymers is possible based on different parameters. Origin, thermal processing Behavior, Mechanism of polymerization, line structure, physical property, Crystallinity, and Degradability are such parameters. The spatial arrangements of substituents like alkyl, phenyl, chloro groups on the carbon chain of polymer are called tacticity. Based on tacticity polymers are classified into isotactic, syndiotactic, and atactic polymers. Tacticity depends on the temperature of formation and solvent used. Steps involved in addition polymerization or chain-growth polymerization are initiation, propagation, and termination. Polythene is an addition polymer that exists as LDPE or HDPE.LDPE is formed from ethylene at a high pressure of 1500-3000 atmosphere at a temperature range of175-250oC in presence of some oxygen, peroxide, or azocompounds as initiators.LDPE has nearly 20–50 branches (both long and short branches) per 1000 linear carbon atoms in the chain molecules. The polymerization at a low temperature and pressure in presence of metal oxide catalyst results in HDPE. 2–5 short branches or side chains per 1000 carbon atoms in the main chain, thus having a higher density range (0.945–0.96) and high melting temperature (125–130°C) compared to LDPE. Polystyrene is a transparent, amorphous addition polymer of styrene.PMMA is an addition polymer of methyl methacrylate.PAN is an acrylic fiber obtained by addition polymerization of acrylonitrile. Condensation polymerization or step-growth polymerization happens by the intermolecular reaction with the elimination of water, HCl, etc. Monomers of nylon 66 are hexamethylene diamine and adipic acid.
The first 6 in 66 denotes the number of carbon atoms in diamine and the second 6 denotes the number of carbon atoms in diacid. Nylon 6 is formed from caprolactam which has 6 carbon atoms in its ring. Bakelite is a three-dimensional phenol-formaldehyde polymer. Kevlar is an aromatic polyamide formed from-phenylene diamine and terephthaloyl chloride. Terylene is the condensation polymer from ethylene glycol and terephthalic acid. A typical Ziegler Natta catalyst is a mixture of titanium tetrachloride and triethyl Aluminium. This catalyst permits the synthesis of unbranched, stereospecific, high molecular weight polyolefins. The process is coordination polymerization and the product is the cis product. Biodegradable polymers get decomposed by bacteria into natural byproducts such as gases (CO2, N2), water, biomass, and inorganic salts. These polymers are esters, anhydrides or amides. PLA(polylactic acid), PGA (Poly(glycolic acid), and PHBV -Poly(β-hydroxybutyrate-co-hydroxy valerate) are examples of biodegradable polymers. The plastic identification code identifies the type of plastic.
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We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
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Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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2. MONOMERS & POLYMERS
• Monomers are small molecules used to
synthesise polymers.
• A polymer is a large molecule made up of
many smaller molecules (monomers).
• The chemical reaction in which the monomers
are joined together by covalent bonds is called
polymerization.
3. CLASSIFICATION OF POLYMERS
• Homopolymers – synthesised from a single
type of monomer. Example : polyethylene and
polypropylene.
These may be represented as : -[A-A-A-A-A-A]• Copolymers – formed from two or more
different types of monomers are called
copolymers.
These may be represented as : -[A-B-A-B-A-B]-
4. Several classes of copolymer are possible
• Statistical copolymer (Random)
ABAABABBBAABAABB
two or more different repeating unit
are distributed randomly
• Alternating copolymer
ABABABABABABABAB
are made of alternating sequences
of the different monomers
• Block copolymer
AAAAAAAAABBBBBBBBB
long sequences of a monomer are followed
by long sequences of another monomer
• Graft copolymer
AAAAAAAAAAAAAAAAAA
B
B
B
B
B
B
Consist of a chain made from one type of
monomers with branches of another type
5. Classification by Chain structure (molecular architecture)
• Linear chains : a polymer consisting of a single continuous chain
of repeat units
• Branched chains :a polymer that includes side chains of repeat
units connecting onto the main chain of repeat units
• Hyper branched polymer consist of a constitutional repeating
unit including a branching groups
• Cross linked polymer :a polymer that includes interconnections
between chains
• Network polymer :a cross linked polymer that includes numerous
interconnections between chains
Linear
Branched
Cross-linked
Direction of increasing strength
Network
6. NOMENCLATURE / NAMING
Generic source-based nomenclature for
polymers
(IUPAC Recommendations 2001)
A generic source-based name comprises two parts:
1) polymer class (generic) name followed by a
colon
2) the actual or hypothetical monomer name(s),
always parenthesized in the case of a copolymer
7. Homopolymers
RULE 1
• The source-based name of a homopolymer is made
by combining the prefix “poly” with the name of the
monomer.
8. General Rules
RULE 2
• A generic source-based name of a polymer has two
components and always parenthesized in the case of a
polymer
I. A polymer class (generic) name (polyG) followed by a
colon
II. The actual of hypothetical monomer name(s)
9. RULE 3
• When more than one type of functional group or
heterocyclic system is present in the polymer
structure, names should be alphabetized, example,
poly(GG’):(A-alt-B)
10. RULE 4
• Polymer class names relevant only to the main chain
are specified in the name, names of side-chain
functional groups may also be included after a
hyphen if they are formed during the polymerization
reaction.
11. RULE 5
• In the case of carbon-chain polymers such as vinyl
polymers or diene polymers, the generic name is to
be used only when different polymer structures may
arise from a given monomeric system.
12. CHARACTERISTICS OF POLYMERS
•
•
•
•
•
•
•
•
•
•
•
Low Density.
Low coefficient of friction.
Good corrosion resistance.
Good mould ability.
Excellent surface finish can be obtained.
Can be produced with close dimensional tolerances.
Economical.
Poor tensile strength.
Low mechanical properties.
Poor temperature resistance.
Can be produced transparent or in different colours.
13. PHYSICAL PROPERTIES
The physical properties of a polymer, such as its strength
and flexibility depend on:
• Chain length - in general, the longer the chains the
stronger the polymer;
• Side groups - polar side groups give stronger attraction
between polymer chains, making the polymer
stronger;
• Branching - straight, un branched chains can pack
together more closely than highly branched chains,
giving polymers that are more crystalline and therefore
stronger;
• Cross-linking - if polymer chains are linked together
extensively by covalent bonds, the polymer is harder
and more difficult to melt.
14. STRENGTH OF POLYMERS
In general, the longer the polymer chain, the stronger the
polymer. There are two reasons for this:
• longer chains are more tangled
• there are more intermolecular forces between the
chains because there are more points of
contact. These forces, however, are quite weak for
polyethene.
• Areas in a polymer where the chains are closely packed
in a regular way are said to be crystalline. The
percentage of crystallinity in a polymer is very
important in determining its properties. The more
crystalline the polymer, the stronger and less flexible it
becomes.
15. • When a polymer is stretched (cold-drawn), a neck
forms. In the neck the polymer chains line up
producing a more crystalline region. Cold-drawing
leads to an increase in strength.
• The first polyethene which was made contained many
chains which were branched. This resulted in a
relatively disorganised structure of low strength and
density. This was called low density polyethene (ldpe).
• In the crystalline form, the methyl groups all have the
same orientation along the chain. This is called the
isotactic form. In the amorphous form, the methyl
groups are randomly orientated. This is called the
atactic form.
• Polymers with a regular structure are said to be
stereoregular.
17. • Both classes of reaction can lead to the formation of
either linear polymers or polymer networks.
Whether the linear chains or polymer networks are
obtained only depends on the number of reactive
entities per monomer.
19. STEP-GROWTH POLYMERIZATION
• In step-growth polymerization, a linear chain results
from the step-wise condensation or addition of
reactive groups of bifunctional monomers.
20. Condensation Polymerization
• Condensation : process in which two monomers
react to form a larger molecule and eliminate a
smaller molecule (usually water, ammonia, methanol
or hydrogen chloride).
• Example : Kevlar, nylon, and Terylene.
21. • Step-Growth polymerization occurs by consecutive reactions in
which the degree of polymerization and average molecular
weight of the polymer increase as the reaction proceeds.
Usually (although not always), the reactions involve the
elimination of a small molecule (e.g., water). Condensation
polymerization may be represented by the following reactions:
Monomer + Monomer
Dimer + H2O
Monomer + Dimer
Trimer + H2O
Monomer + Trimer
Tetramer + H2O
Dimer + Dimer
Tetramer + H2O
Dimer + Trimer
Pentamer + H2O
Trimer + Trimer
Hexamer + H2O
• Generally, the reactions are reversible, thus the eliminated
water must be removed if a high molecular weight polymer is to
be formed.
• Based on the assumption that the polymerization kinetics are
independent of molecular size, the condensation reactions may
all be simplified to:
~~~~COOH + HO~~~~
~~~~COO~~~~ + H2O
22. • When a monocarboxylic acid reacts with an amine,
amide is formed.
• When a carboxylic acid with two –COOH groups
reacts with an amine with two –NH2 groups, a
polyamide is formed.
23. • When a monocarboxylic acid reacts with an alcohol,
and ester is formed.
• When a carboxylic acid with two –COOH groups
reacts with an alcohol with two –OH groups, a
polyester is formed.
24. Addition Polymerization
• Addition : monomers with double bonds are joined
together by covalent bonds to form a large molecule
(polymer) without loss of a small molecule.
• Monomers for making addition polymers may be
alkenes (ethene and propene) or alkene derivatives
(choloroethene, CH2 = CHCl)
• In the formation of addition polymers, the carboncarbon double bond in each monomer is broken
open and replaced by a carbon-carbon single bond.
25. • Chain polymerization proceeds by the succession of
three steps :
– Initiation : The first active center (radical, anion or
cation) is formed and the growth of the chain is
initiated.
– Propagation : Growth of the polymer chain occurs
by the successive addition of monomers to the
active center at the end of the chain.
– Termination : Growth is terminated by either
neutralization or transfer of the active center.
27. Vinyl monomers for addition polymerizations
The only exceptions to the unreactivity
of tri- and tetra-substituted vinyl
monomers are those with fluorine, like
tetrafluoroethylene (CF2=CF2). The
main cause of this reactivity pattern is
the steric size of the substituents.
33. APPLICATION
• Polymeric materials are used in and on soil to improve
aeration, provide mulch, and promote plant growth and
health.
Medicine
• Many biomaterials, especially heart valve replacements
and blood vessels, are made of polymers like Dacron,
Teflon and polyurethane.
Consumer Science
• Plastic containers of all shapes and sizes are light weight
and economically less expensive than the more
traditional containers. Clothing, floor coverings, garbage
disposal bags, and packaging are other polymer
applications.
34. Industry
• Automobile parts, windshields for fighter planes,
pipes, tanks, packing materials, insulation, wood
substitutes, adhesives, matrix for composites, and
elastomers are all polymer applications used in the
industrial market.
Sports
• Playground equipment, various balls, golf clubs,
swimming pools, and protective helmets are often
produced from polymers.
