Polymer Engineering

Classification of Polymers

• Natural Polymers

• Synthetic Polymers

• Deformable Materials

• Non-Deformable Materials

• Thermoplasts

• Duromers

• Elastomers

• Dispersions

• Varnishes and Paints

• Functional Polymers

Molecular Architecture

• Linear Homopolymer

• Branched Homopolymer

• Statistical Copolymer

• Block Copolymer

• Multi-block Copolymer

• Graft Copolymer

Examples

• High Density Polyethylene (HDPE)

• Low Density Polyethylene (LDPE)

• Styrene Acrylonitrile Copolymer (SAN)

• Styrene-Butadiene Block Copolymer (SB)

• Styrene-Butadiene-Styrene Block Copolymer (SBS)

• Styrene-Butadiene Graft Copolymer (B-g-S)

Non-Deformable Polymers - Examples

• Dispersions based on styrene/n-butylacrylate

• Acrylamide-sodiumacrylate

• Alkylacrylate-copolymers

• Superabsorber

• Polycarboxylate

• Polyethyleneimine

• Paper finishing

• Detergent additives

• Partially crosslinked Acrylamide-sodiumacrylate-alkylene-copolymer

Application

• Precipitants

• Paints

• Polymer

Functional Polymers

• Functional variety by changing the length of molecules…

Example:

• Polymers based on acrylic acid

  • Molar mass 5,000 g/mol: Dispergents

  • Molar mass 70,000 g/mol: Detergents

  • Molar mass 2 Mio. g/mol: Precipitants, Thickeners, Superabsorbers

  • Cross-linked

Functional Polymers - Copolymerization

• Polyacrylic acid

• Acrylic acid/Maleic acid Copolymer

• Polyvinylpyrrolidone

• Vinylpyrrolidone/Vinylacetate Copolymer

• $CH_2=CH$

• $CH_2=CH$

• $COOH$

• $CH_2=CH$

• $CH_2=CH$

• $COOH$

• $COOH$

• $CH_2=CH$

• $CH_2=CH$

• $N=O$

• $CH_2=CH$

• $N=O$

• $CH_2=CH$

• $OOCCH_3$

Classification of Thermoplastic Polymers

• High Temperature Thermoplasts

  • TCU: 150°C – 260°C

  • Examples: PAEK, LCP, PAI, PPS, PSU, PEI, PES

• Technical Polymers

  • TCU: 90°C - 140°C

  • Examples: PC, PBT, PET, PA, PPE-Blends, POM, SAN, ABS, PMMA

• Standard Polymers

  • TCU: < 90°C

  • Examples: PS, PVC, LDPE, HIPS, LLDPE, HDPE, PP

Thermoplastic Polymers - Examples

• Polyethylene (LDPE, HDPE, LLDPE): $CH<em>2-CH</em>2$

• Polypropylene (PP): $CH<em>2-CH(CH</em>3)$

• Polystyrene (PS): $CH<em>2-CH(C</em>6H_5)$

• Polyvinylchloride (PVC): $CH_2-CH(Cl)$

Thermoplastic Polymers - More Examples

• Polyamides (PA-X.Y, PA-X): Reactions of diamines and dicarboxylic acids forming amide links.

• Polyethyleneterephthalate (PET, X=2)

• Polybutyleneterephthalate (PBT, X=4)

• Polymethylmethacrylate (PMMA): $C(CH<em>3)(COOCH</em>3)-CH_2$

• Polyoxymethylene (POM): $(CH<em>2O)</em>n$

High Temperature Thermoplasts - Structures and Properties

• Polyethersulphone (PES): Continuous use temperature 190°C

  • $[O-C<em>6H</em>4-SO<em>2-C</em>6H<em>4]</em>n$

• Polysulphone (PSU): Continuous use temperature 160°C

  • $[O-C<em>6H</em>4-SO<em>2-C</em>6H<em>4-C(CH</em>3)<em>2-C</em>6H<em>4]</em>n$

• Polyetherimide (PEI): Continuous use temperature 180°C

  • Complex structure involving imide and ether linkages.

• Polyphenylenesulfide (PPS): Continuous use temperature 240°C

  • $[C<em>6H</em>4-S]_n$

High Temperature Thermoplasts - More Structures and Properties

• Polyphenylenesulphone (PPSU): Continuous use temperature 160°C

  • $[C<em>6H</em>4-SO<em>2-C</em>6H<em>4-O-C</em>6H<em>4]</em>n$

• Polyetheretherketone (PEEK): Continuous use temperature 250°C

  • $[O-C<em>6H</em>4-O-C<em>6H</em>4-CO-C<em>6H</em>4]_n$

• Polyetherketoneetherketoneketone (PEKEKK): Continuous use temperature 250°C

  • $[O-C<em>6H</em>4-CO-C<em>6H</em>4-O-C<em>6H</em>4-CO-C<em>6H</em>4-CO-C<em>6H</em>4]_n$

Examples for Duromers

• Unsaturated Polyester Resin (UP) - Use temperature: 120 – 150 °C

• Epoxy Resin (EP) - Use temperature: 80 – 180 °C

• Phenolic Resin (PF) - Use temperature: 110 – 150 °C

• Melamin-Formaldehyde Resin (MF) - Use temperature: 80 – 120 °C

• Vinylester Resin (VE) - Use temperature: 100 – 140 °C

Molecular Structure of a Polyurethane Elastomer

• Soft segment

• Stiff segment

Energy for Production

The energy required to produce different materials in kg oil equivalent per liter of material, from lowest to highest:

• Duromers

• Low density polyethylene

• Polypropylene

• High density polyethylene

• Polyvinylchloride

• Polystyrene

• Steel

• Copper

• Aluminum

From Crude Oil to Polymers

• Naptha is cracked and separated to produce:

  • C2 (Ethylene) -

    • PE

    • $C<em>2H</em>4Cl_2$ -

      • PVC (via C2H3Cl )

  • C3 (Propylene) -

    • PP

  • C6 (Benzene) -

    • Ethylbenzene ($C<em>8H</em>{10}$) -

      • Styrene -

        • PS

Types of Polymerization Reactions

• Chain-growth polymerization

  • Radical chain polymerization

  • Cationic chain polymerization

  • Anionic chain polymerization

  • Coordinative chain polymerization

• Step-growth polymerization

  • Polycondensation

  • Polyaddition

Structure of Bifunctional Monomers

• O=C=N-R-N=C=O + HO-R'-OH -> [-R-N-C-O-R'-O-C-N-]_n (Polyaddition)

• Monomers suitable for polymerization need to be at least bifunctional

Functionality of Monomers

• MONOMER Monofunctional group or Monofunctional group

• MONOMER Bifunctional group

Polycondensation of PA6.6

• H2N-(CH2)6-NH2 + HOOC-(CH2)4-COOH -> [-NH-(CH2)6-NH-CO-(CH2)4-CO-]n + nH2O

• Loss of water during polymerization.

Radical Polymerization under High Pressure (LDPE)

• Starting reaction: ROOR -> 2RO with "relic" R typically H in case of $H<em>2O</em>2$

• Chain Growth: RO + H2C=CH2 -> RO-H2C-CH2 followed by RO-(CH2-CH2)n + H2C=CH2 -> RO-(CH2-CH2){n+1}

• Termination:

  • Disproportionation: RO-(CH2-CH2)n-CH2-CH2 + RO-(CH2)n-CH2-CH2 -> RO-(CH2-CH2)n-CH=CH2 + RO-(CH2-CH2)n-CH2-CH3

  • Recombination: RO-(CH2-CH2)n + RO-(CH2-CH2)n -> RO-(CH2-CH2)_{2n}-OR

Overview of Polymerization Methods

• Radicalic chain polymerization:

  • Low density polyethylene (LDPE)

  • Polymethylmethacrylate

  • Polystyrene

  • Polyacrylicacid, -acidester, -amide, -nitrile

  • Polyvinylchloride

  • PTFE and Polyvinylidenefluoride

• Anionic chain polymerization:

  • Polybutadiene

  • Polyformaldehyde

  • Polyisoprene

  • Poly-ε-caprolactam

  • Polymethylcyanoacrylate

  • Technically most important method for manufacturing block-copolymers: Styrene-Butadiene Polyetherester, with hard and soft blocks

• Cationic chain polymerization (technically less important):

  • Polyisobutylene

  • Polyalkylvinylether

  • Polyformaldehyde

• Polyinsertion:

  • High density polyethylene (HDPE, ZN)

  • Isotactic polypropylene (PP, ZN, Metallocene)

  • Linear low density polyethylene (LLDPE, ZN, Metallocene)

  • Ethylene-Propylene-Terpolymer (EPDM, ZN, Metallocene)

  • (ZN: Ziegler-Natta-Catalyst, Metallocene: Metallocene-Catalyst)

High Pressure Polymerization of Low Density Polyethylene

• Autoclave reactor or Tube reactor, Compressor, Precompressor

• Low pressure separator, High pressure separator

• High pressure circuit, Low pressure circuit

• Extruder : resulting in Pellets

• Temperature: 200 – 300°C

• Pressure: 2000 – 3000 bar

• Reactants

Processing Scheme for Linear Low Density Polyethylene

• Hydrogen, Comonomer, Ethylene

• Fluidized bed reactor

• Catalyst

• Compressor, Cooler, Polymer

• Temperature: 85 – 100°C

• Pressure: 20 – 40 bar

• Residence times of hours

• Reactor volumes of several 100 m³

Summary of Intro to Polymer Materials

• Polymer materials are ubiquitous.

• The world-wide consumption of polymer materials is significantly higher than that of steel if related to volume.

• Classification of polymers:

  • Natural and synthetic polymers

  • Deformable and non-deformable polymers

• Molecular architecture:

  • Linear and branched homopolymers

  • Statistical, block and graft copolymers

• Chemical structure of various thermoplastics and duromers

• Polymerization methods

• Production of low density polyethylenes as examples of polymerization processes

Molecular Mass of Polymers

• $M<em>i = P</em>iM<em>g + 2M</em>{EG} ≈ P<em>iM</em>g$ (if $P_i$ is high)

  • $M_i$: Molar mass of macromolecule i

  • $P_i$: Degree of polymerization of macromolecule i

  • $M_g$: Molar mass of the monomer unit

  • $M_{EG}$: Molar mass of the endgroup

Molar Masses of Structural Units of Some Polymers

• PE: $M<em>g = (2x12 + 4x1) g/mol = 28 g/mol$ ($CH</em>2-CH_2$)

• PP: $M<em>g = (3x12 + 6x1) g/mol = 42 g/mol$ ($CH</em>2-CH(CH_3)$

• PVC: $M<em>g = (2x12 + 3x1 + 1x35) g/mol = 62 g/mol$ ($CH</em>2-CH(Cl)$

Discrete Molar Mass Distributions

• Number average: $M<em>n = \frac{\sum</em>i n<em>i M</em>i}{\sum<em>i n</em>i} = \sum<em>i M</em>i f(M_i)$

• Weight average: $M<em>w = \frac{\sum</em>i n<em>i M</em>i^2}{\sum<em>i n</em>i M<em>i} = \frac{\sum</em>i m<em>i M</em>i}{\sum<em>i m</em>i} = \sum<em>i M</em>i h(M_i)$

• Definitions of average molar masses

• Number distribution: $f(M<em>i) = \frac{n</em>i}{\sum n_i}$

• Mass distribution: $h(M<em>i) = \frac{m</em>i}{\sum m_i}$

• $m<em>i = M</em>i n_i$

Continuous Molar Mass Distributions

• Number average: $M<em>n = \int</em>0^{\infty} M g(M) dM$

• Weight average: $M<em>w = \int</em>0^{\infty} M w(M) dM$

• Polydispersity factor: $PD = \frac{M<em>w}{M</em>n} ≥ 1$

• Relations between distribution functions

  • $w(M) = \frac{M g(M)}{M_n}$

  • $\int_0^{\infty} w(M) dM = 1$

  • $\int<em>0^{\infty} g(M) dM = \frac{1}{M</em>n}$

Example for Different Distributions

• Coins from a moneybox

  • Nominal Value, Number $n<em>i$, Mass $M</em>i$,
    $m<em>i=M</em>i n_i$

  • Number average: $\frac{\sum n<em>i M</em>i}{\sum n_i}$

  • Weight average: $\frac{\sum M<em>i^2 n</em>i}{\sum M<em>i n</em>i}$

Molar Mass Averages of Some Commercial Polymer Materials

Molecular Modification by Branching

• Low Density Polyethylene (LDPE) - Long-chain branches, High pressure polyethylene

• High Density Polyethylene (HDPE) - Very few short-chain branches, Low pressure polyethylene

• Linear Low Density Polyethylene (LLDPE) - Variable C1 to C6-branches, Low pressure polyethylene

Modification of Low Density Polyethylenes by Copolymerization

• Non-polar comonomers are used to create LLDPE.

• Butene: $CH<em>2=CH-CH</em>2-CH_3$

• Hexene: $CH<em>2=CH-CH</em>2-CH<em>2-CH</em>2-CH_3$

• Octene: $CH<em>2=CH-CH</em>2-CH<em>2-CH</em>2-CH<em>2-CH</em>2-CH_3$

Ethylene Copolymers with Polar Groups

• Ethylene / Vinylacetate (E/VA) - $CH<em>2=CH-OOCCH</em>3$

• Ethylene / Acrylic acid (E/AA) - $CH_2=CH-COOH$

• Ethylene / Butylacrylate (E/BA) - $CH<em>2=CH-COOC</em>4H_9$

• Ethylene / Butylacrylate / Acrylic acid (E/BA/AA)

Molecular Modification by Changing the Tacticity

• Isotactic polypropylene: All methyl groups on the same side

• Syndiotactic polypropylene: Methyl groups alternate sides

• Atactic polypropylene: Methyl groups are randomly oriented

Summary of Structure of Macromolecules

1. Mathematical definition of molar masses (discrete and continuous distributions)

   • Number average: Mn

   • Weight average: Mw

2. Molecular modification

   • Branching: LDPE, LLDPE, HDPE

   • Copolymerization

   • Tacticity

Methods for the Determination of Molar Masses

• Osmometry

• Light scattering

• Gel permeation chromatography (GPC)

• Viscometry

Membrane Osmometry

• Van‘t Hoff law: $\Pi = \frac{R T c}{M}$, $\Delta h = \frac{\Pi}{\rho g}$

  • $\Pi$: Osmotic pressure

  • $g$: Constant of gravity

  • $\rho$: Density

  • $c$: Concentration

  • $M$: Molar mass

  • $R$: Gas constant

  • $T$: Absolute temperature

  • $\Delta h$: Height difference due to osmotic pressure

Example for Osmometric Data

• Osmotic pressure as a function of concentration for a polystyrene in toluene

Information Derived from Osmometry

*$\frac{\Pi}{RT} = \frac{1}{M_n} + Bc$

• $M_n$ : Number average molar mass

• $B$ : Second virial coefficient

• With osmometry the number average molar mass Mn can be measured

The Θ-Solution

• A polymer solution for which B=0 is called a theta(Θ)-solution.

• To a Θ-solvent the undisturbed chain statistics can be applied.

Principles of Light Scattering

• Measuring principle and definition of scattering angle Θ

• Polymer solution, Primary beam, Rotating photocell (detector)

• Scattering intensity i(Θ) as a function of the scattering angle Θ

Equations for the Evaluation of Light Scattering Experiments

• $i(\Theta,c) = i(0,c) \frac{V_0}{r^2} \frac{1 + cos^2 \Theta}{2}$

  • $i(\Theta,c)$: Intensity of light scattered at an angle Θ from a polymer solution of concentration c

  • $i_0$: Intensity of incident light

  • $V_0$: Sample volume

  • $r$: Distance between scattering volume and photo cell

Evaluation of Light Scattering Experiments (cont.)

• $\frac{K c}{i(\Theta)} = \frac{1}{M_w P(\Theta)} + 2Bc$

  • $K = 4 \pi^2 n<em>1^2 (dn/dc)^2 / (N</em>L \lambda^4)$

    • $n_1$: Refractive index of solvent

    • $n$: Refractive index of solution

    • $dn/dc$: Refractive index increment of solution

    • $\lambda = \lambda<em>0/n</em>1$: Wavelength of incident light in solution

    • $\lambda_0$: Wavelength of incident light

    • $N_L$: Avogadro’s number

  • $P(\Theta) = 1 - \frac{16 \pi^2 h^2}{3 \lambda^2} sin^2(\Theta/2)$

    • $h$: Radius of molecule

    • $B$: Second virial coefficient

• From light scattering experiments the mass average molar mass $M_w$, the average radius of the molecules h, and the second virial coefficient B can be determined.

Gel Permeation Chromatography (GPC)

• Schematic illustration of the GPC

• Mechanism of separation by molecule size in a gel

• Large molecules elute first, followed by smaller molecules

Definition of the Viscosity of a Liquid

• $\tau = \eta \dot{\gamma}$

  • $\dot{\gamma} = \frac{dv_x}{d}</p></li></ul></li></ul><p><br><strong>Term 1:</strong> Natural Polymers<br><strong>Definition 1:</strong> Polymers derived from natural sources<br><strong>Term 2:</strong> Synthetic Polymers<br><strong>Definition 2:</strong> Polymers synthesized from chemical processes<br><strong>Term 3:</strong> Deformable Materials<br><strong>Definition 3:</strong> Polymers that can undergo significant deformation without breaking<br><strong>Term 4:</strong> Non-Deformable Materials<br><strong>Definition 4:</strong> Polymers that resist deformation<br><strong>Term 5:</strong> Thermoplasts<br><strong>Definition 5:</strong> Polymers that soften when heated and harden when cooled, allowing for reshaping<br><strong>Term 6:</strong> Duromers<br><strong>Definition 6:</strong> Polymers that undergo irreversible hardening when heated and cannot be reshaped<br><strong>Term 7:</strong> Elastomers<br><strong>Definition 7:</strong> Polymers with elastic properties, capable of returning to their original shape after deformation<br><strong>Term 8:</strong> Dispersions<br><strong>Definition 8:</strong> Mixtures in which one substance is dispersed throughout another<br><strong>Term 9:</strong> Varnishes and Paints<br><strong>Definition 9:</strong> Coatings consisting of a resin dissolved in a solvent, often with pigments<br><strong>Term 10:</strong> Functional Polymers<br><strong>Definition 10:</strong> Polymers designed for specific applications due to their unique chemical or physical properties<br><strong>Term 11:</strong> Linear Homopolymer<br><strong>Definition 11:</strong> A polymer composed of a single type of monomer, arranged in a linear chain<br><strong>Term 12:</strong> Branched Homopolymer<br><strong>Definition 12:</strong> A polymer composed of a single type of monomer with branches extending from the main chain<br><strong>Term 13:</strong> Statistical Copolymer<br><strong>Definition 13:</strong> A polymer composed of two or more different monomers, arranged randomly<br><strong>Term 14:</strong> Block Copolymer<br><strong>Definition 14:</strong> A polymer composed of long sequences (blocks) of different monomers<br><strong>Term 15:</strong> Multi-block Copolymer<br><strong>Definition 15:</strong> A copolymer containing multiple blocks of different monomer sequences<br><strong>Term 16:</strong> Graft Copolymer<br><strong>Definition 16:</strong> A polymer with chains of one type of monomer grafted onto a backbone of another type of monomer<br><strong>Term 17:</strong> Chain-growth polymerization<br><strong>Definition 17:</strong> Polymerization in which monomers add to the growing chain one at a time<br><strong>Term 18:</strong> Step-growth polymerization<br><strong>Definition 18:</strong> Polymerization by combining monomers through a series of individual reactions<br><strong>Term 19:</strong> Polycondensation<br><strong>Definition 19:</strong> A type of step-growth polymerization with the release of a small molecule like water.<br><strong>Term 20:</strong> Polyaddition<br><strong>Definition 20:</strong> A type of step-growth polymerization without the release of a small molecule<br><strong>Term 21:</strong> Discrete Molar Mass Distributions<br><strong>Definition 21:</strong> Distribution of molar masses described using number average<br><strong>Term 22:</strong> Continuous Molar Mass Distributions<br><strong>Definition 22:</strong> Distribution of molar masses described using integration<br><strong>Term 23:</strong>$R$<br><strong>Definition 23:</strong> The gas constant<br><strong>Term 24:</strong>$T$<br><strong>Definition 24:</strong> Absolute temperature<br><strong>Term 25:</strong>$\Delta h$$
    Definition 25: Height difference due to osmotic pressure
    Term 26: The Θ-Solution
    Definition 26: A polymer solution for which B=0