<h3 id="successpolymerslecture-3success"><Success>Polymers(Lecture-3)</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> </div> <div style='float: right; width:0%;'> <!----> </div>

### <Success>Based on mechanical behavior</Success> <div style='float: left; width:50%;font-size:28px;text-align:left'> <ul> <li>Stress: Force/area $=F / A$</li> <li>Strain: change in dimension/ original length $=\Delta L / L$</li> <li>$\frac{\text { stress}}{\text { strain }}=$ Modulus (Resistance to deformation)</li> <li>Fibers :</li> <li>High modulus</li> <li>High tensile strength</li> <li>Elongation is low</li> <li>High elongation $\geqslant 5-10$ times, $\hspace{1mm}$ $\geqslant 500-$ $1000 %$</li> <li>Reversible</li> <li>Modules is low</li> </ul> </div> <div style='float: right; width:50%;'> <img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/2448ff64-d124-427b-c4cd-21b404d82a00/public" width="70%"> <!----> </div>

<h3 id="successelastomersuccess"><Success>Elastomer</Success></h3> <div style='float: left; width:50%;font-size:30px;text-align:left'> <ul> <li>Low modulus</li> <li>High elongation</li> <li>Reversible</li> <li>Very weak intermolecular forces</li> <li>Sightly cross-linked</li> <li>Buna - S</li> <li>Neoprene</li> </ul> <!--5. Based on mechanical behavior--> <!--Stress: Force/area $=F / A$--> <!--Strain: change in dimension/ original length $=\Delta L / L$--> <!--$\frac{\text { stress}}{\text { strain }}=$ Modulus (Resistance to deformation)--> <!--fibers : --> <!--high modulus--> <!--high tensile strength --> <!--elongation is low--> <!--Nylon 6,6, PET fibers --> <!--high elongation $\geqslant 5-10$ times. --> <!--$\hspace{20mm}$ $\geqslant 500-$--> <!--$1000 \%$--> <!--Reversible. --> <!--Modulus is low--> </div> <div style='float: right; width:50%;'> <img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/95029a69-f8fd-435c-7dcf-ef211e957e00/public" width="60%"> <!----> <!----> </div>

<h3 id="successplasticssuccess"><Success>Plastics</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> <ul> <li>A large variety of polymers with wide-range of mechanical properties between elastomers and fibers</li> <li>Rigid plastics - intermolecular forces are higher</li> <li>High modulus</li> <li>Very low elongation</li> <li>Polystyrene, PMMA, phenol-formaldehyde resin.</li> <li>Flexible plastics - intermolecular forces are low</li> <li>Low modulus</li> <li>High elongation (partially reversible)</li> <li>Polyethylene, polypropylene, etc</li> </ul> </div> <div style='float: right; width:0%;'> <!----> </div>

<h3 id="successbased-on-thermal-behaviorsuccess"><Success>Based on thermal behavior</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> <ul> <li><strong>Thermoplastics:</strong> Linear or slightly branched polymers capable of repeatedly softening on heating and hardening on cooling. PE, PVC, PS, etc…</li> <li><strong>Thermosetting polymers</strong>: Cross-linked or heavily branched which undergo extensive Cross-linking in moulds and become infusible Non-recyclable polymer materials</li> <li>Bakelite, urea formaldehyde</li> </ul> </div> <div style='float: right; width:0%;'> <!----> </div>

<h3 id="successmw-of-polymersuccess"><Success>MW: of polymer</Success></h3> <div style='float: left; width:50%;font-size:30px;text-align:left'> <ul> <li>Average molecular weight</li> <li>Arithmetic mean: no. average MW $\overline{(M_n)}$</li> <li>Weight average MW $\overline{(M_w)}$</li> <li>$\frac{\bar{M}_w}{\bar{M}_n}$ = $\text { PDI }=\text { Polydispersity index }$</li> </ul> </div> <div style='float: right; width:50%;'> <!--<img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/0a9eb487-940e-47cb-0c13-1229af20ce00/public" width="60%" >--> <img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/cc53e4bf-d171-4c62-7758-a4d7a98a2200/public" width="100%" > </div> <div style='float: right; width:0%;'> <!----> </div>

<h3 id="successquestionssuccess"><Success>Questions</Success></h3> <div style='float: left; width:100%;font-size:26px;text-align:left'> <ul> <li>Explain the terms polymer and monomer</li> <li>What are natural and synthetic polymers? Give two examples of each type</li> <li>Distinguish between the terms homopolymer and copolymer and give an example of each</li> <li>How do you explain the functionality of a monomer?</li> <li>Define the term polymerisation</li> <li>Is $ [\mathrm{NH}-\mathrm{CHR}-\mathrm{CO}]_n$ a homopolymer or copolymer?</li> <li>In which classes, the polymers are classified on the basis of molecular forces?</li> <li>How can you differentiate between addition and condensation polymerisation?</li> <li>Explain the term copolymerisation and give two examples</li> <li>Write the free radical mechanism for the polymerisation of ethene</li> <li>Initiation $\rightarrow$ Propagation $\rightarrow$ termination</li> </ul> </div> <div style='float: right; width:0%;'> <!----> <!----> <!---->

<h3 id="successquestionssuccess-1"><Success>Questions</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> <ul> <li>Define thermoplastics and thermosetting polymers with two examples of each</li> <li>Classify the following as addition and condensation polymers: Terylene, Bakelite, Polyvinyl chloride, Polythene</li> <li>Arrange the following polymers in increasing order of their intermolecular forces</li> <li>Nylon 6,6, Buna-S, Polythene</li> <li>Nylon 6, Neoprene, Polyvinyl chloride</li> <li>Write the name and structure of one of the comman initiators used in free radical addition polymerisation</li> <li>What does ‘Bu’ & ‘Na’ & ‘S’ stand for in Buna-5 polymer respectively?</li> </ul> </div> <div style='float: right; width:0%;'> <!----> <!----> <!----> </div>

<h3 id="successexamples-of-polymerssuccess"><Success>Examples of polymers</Success></h3> <div style='float: left; width:50%;font-size:30px;text-align:left'> Examples of different polymers: Preparation methods and some applications - <ul> <li>Polyethylene (Polythene) (I) LDPE (LDP)</li> </ul> <p>n$CH_2=CH_2$ $\xrightarrow[Temp (350K-570K) (Trace of dioxygen) / peroxide]{high Pressure(1000-2000 atom)}$ $(-CH_2-CH_2-)_n$</p> <ul> <li>Chain transfer</li> <li>Polymers with long-chain branchig</li> </ul> </div> <div style='float: right; width:50%;'> <img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/4abd98eb-8e6b-457a-3e2e-fc6aa982e700/public" width="50%"> <!----> </div>

<h3 id="successexamples-of-polymerssuccess-1"><Success>Examples of polymers</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> <ul> <li>Low density due to low dense packing</li> <li>Flexible and low utility over a long range of temp</li> <li>Good combination of strength, flexibility, impact resistance</li> <li>Highly resistance & water even at hightemp</li> <li>Electrical insulator</li> <li>Good Solvent, chemical, oxidation resistance</li> </ul> <!--Examples of different polymers: Preparation methods and some applications ---> <!--1. Polyethylene (Polythene)--> <!--(I) LDPE (LDP)--> <!--n$CH_2=CH_2$ $\xrightarrow[Temp (350K-570K) (Trace of dioxygen) / peroxide]{high Pressure(1000-2000 atom)}$--> <!-- $(-CH_2-CH_2-)_n$--> <!--Chain transfer.--> <!--Polymers with long-chain branchig.--> </div> <div style='float: right; width:0%;'> <!----> <!----> </div>

<h3 id="successexamples-of-polymerssuccess-2"><Success>Examples of polymers</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> <p>(I) HDPE (HDP)</p> <ul> <li>Addition polymerization of ethylene in presence of catalyst such as titanium tetrachloride and triethyl aluminium (Ziegler- Natta)</li> <li>Temp 333K to 343K</li> <li>Pressure 6-7 atm.</li> <li>(Giulio & Natta Karl Ziegler 1963)</li> <li>Linear</li> <li>High density due to close packing</li> <li>Chemically inert</li> <li>More tougher and harder</li> <li>Buckets, dustbins, bottles, pipes etc.</li> </ul> </div> <div style='float: right; width:0%;'> <!----> </div>

<h3 id="successteflonsuccess"><Success>Teflon</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> <ol start="2"> <li>Poly (tetrafluoroethylene) [Teflon]</li> </ol> <p>$n C F_2=C F_2 \xrightarrow[\text { high pressure }]{\text { Catalyst }} \quad [ -CF_2-\mathrm{CF}_2-]_n$ (tetrafluoroethylene)</p> <ul> <li>Non-stick</li> <li>Resistance to corrossire reagents</li> <li>Chemically inert</li> <li>Lubricants</li> <li>Making oil seals and gaskets</li> </ul> </div> <div style='float: right; width:0%;'> <!----> </div>

<h3 id="successpolyacrylonitrilesuccess"><Success>Poly(acrylonitrile)</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> <ol start="3"> <li>Poly (acrylonitrile)</li> </ol> <img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/e50f03f6-9243-4182-bb8d-39a3552ee000/public" width="80%" > <!--<span style="color:green">$nCH_2=CH-CN^-$ (acrylonitrile) $\xrightarrow[\text { peroxide Catalyst }]{\text { Polymerization }}$ $(-CH_2-CH(-CN^-))_n$ PAN</span>--> <ul> <li>Substituent for wool in making commercial fiber as orlon or acrylins</li> <li>Styrene - acrylonitrile coplymers (SAN)</li> </ul> </div> <div style='float: right; width:0%;'> <!----> </div>

<h3 id="successcondensation-polymersuccess"><Success>Condensation polymer</Success></h3> <div style='float: left; width:100%;font-size:30px;text-align:left'> <p>Condensation polymer / Step-growth mechanism</p> <ul> <li>Polyamides: $[-CO-NH-]$</li> <li>Diacid + Diamine $\rightarrow$ Direct Amidation</li> <li>Cyclic amides (lactams) $\rightarrow$ Ring opening polymerisation</li> <li>Nylon 6,6, Nylon 6/6, Nylon-6-6</li> </ul> <!--<span style="color:green">n$H_2N-(CH_2)_6 -NH_2 (Hexamethylenediamine) + nHOOC-(CH_2)_4-COOH$ (adipic acid) $\rightarrow$ $[-HN-(CH_2)_6-NH-CO-(CH_2)_4-CO-]_n$ (hexamethylene adipamide) + (2n-1) $H_2 O$</span>--> <img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/a14bf096-d7b0-4a23-96ce-6d7279b05e00/public" width="50%" > </div> <div style='float: right; width:0%;'> <!----> </div>

<h3 id="successnylonsuccess"><Success>Nylon</Success></h3> <div style='float: left; width:80%;font-size:30px;text-align:left'> <img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/5e54158a-0685-4928-92de-04c00b317200/public" width="70%" > <ul> <li>Nylon 6,6</li> <li>Hosiery textile</li> <li>Strech fabrics</li> <li>Sheets</li> <li>Tire reinforcement</li> <li>Fabrics</li> </ul> </div> <div style='float: right; width:0%;'> <!----> </div>

<div style='float: left; width:100%;font-size:30px;text-align:left'> </div> <h3 id="successthank-yousuccess"><Success>Thank you</Success></h3> <div style='float: right; width:0%;'> <!----> </div>