Macromolecular compounds Martin Keppert Martin Keppert Department of materials engineering and chemistry Department of materials engineering and chemistry Office A 329, office hours Monday 14 Office A 329, office hours Monday 14 - - 16 16 [email protected][email protected]web: web: tpm.cvut.cz tpm.cvut.cz
55
Embed
Martin Keppert Department of materials engineering and ...tpm.fsv.cvut.cz/vyuka/buc/buc_polymers.pdf · Martin Keppert Department of materials engineering and chemistry Office A 329,
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Department of materials engineering and chemistryDepartment of materials engineering and chemistryOffice A 329, office hours Monday 14Office A 329, office hours Monday 14 --1616
� production and properties of synthetic polymers on C basis
� synthetic polymers on Si basis
homopolymer copolymer
• Makromolecular compound (polymer)matter which structure is formed by chain of repeatingunits – identical or similar structure units (monomers)
Fundamental terms
Fundamental terms
� biopolymersnatural compound, founded in organisms(proteins, saccharides)
� natural polymer materialsmaterials produced from natural polymeric raw materials (timber, natural rubber)
� synthetic polymerssynthetic polymers produced from simple organickolecules(plastics, rubbers)
SYNTHETIC POLYMERSELASTOMERSElastic deformation
PLASTICSplastic deformation
rubbers termoplasticsRepeatedly shapeable
after heating
thermosetsAfter hardening are no
more shapeable
Fundamental terms
Bio-Macromolecules
proteins chains of amino acidsAlaninThe simplest amino acid
polysacharides chains of saccharidesGlucose
nucleic acids DNA and RNA
(Poly)-Saccharides
Monosacchardides: glucose
Saccharides (carbohydrates) – the most abundant biomolecules –substances in living organisms„used“ for construction or storage of energy
Polysaccharides: chains of monosaccharides (more than 10)formed by condensationof monos. units
Amylose = polymer of glucosecomponent of starch
α-D-glukopyranose
Synthetic polymers
Macromolecules based on:
a) carbon basischains of (simple) organic molecules
Poly-propylene
b) silicon basis
PDMS poly-dimethyl-silicone
Raw materials for organic chemistry
Fossil: crude oil – mixture of hydrocarbons and other organiccompounds – phenols, heterocycles…
natural gas – mostly methane CH4, small amouts of other gaseous hydrocarbons, H2S, He…
coal – sedimentary rock formed by organic (aromatic)compounds, 80-90 % of C
Renewable: wood (or biomass in general)
PhotosynthesisConversion of CO 2 gas from air to saccharides-Takes place in plants-Needs energy – photosynthesis isconversion of ligth energy of sunto chemical energyof saccharides
6 CO2+6 H2O → C6H12O6 + 6 O2
Glucose
Energy of light
The only process for conversionof light to chemical energy →
responsible also for oil and coal
Chemistry of wood
Organic matter: contains C (49 %), O (44 %), H, N, S..
Structure of wood: cellulose - structurehemicellulose - structurelignin – filler of celulose structure
Properties of wood: inhomogenity and anisotropy – mechanicalproperties depends on direction (tree rings) and position
E.g. tensile strength: 250 and 10 MPa (along x transversalto the fibres)
CellulosePrincipal building material of plant cellsPolymer of monosaccharide β-D-glukopyranoseLong chains – fibers (to 10 000 units; i.e. to 4 mm) – bonded
also transversaly by hydrogen bonds → large, insoluble molecules
Polymer chain
Transversal hydrogen bonds
Hemi-cellulosePoly-saccharide formed by various mono-saccharides
Similar to cellulose, but:
Smaller molecules than cellulose (to 250 units)
Lower strength and higher solubility than cellulose
LigninVarious large organic compounds, it fills the structure madeby cellulose
Soluble in alkaline solutions
Use of wood in buildingsDirect – wooden constructions, roof constructions…
Wood-based boards – glued pieces (small, large…) of wood
plywood
OSB oriented strand board
chip-board
Burning of wood
• Burning = oxidation of wood components by oxygen from air
over 100 C: dehydration of cellulose to water and carbon130-150 C: decomposition of lignin – browning of wood180-200 C: fast dehydration to water steam and CO2
270-280 C: burning exotermic oxidation by oxygen
Pyrolysis of wood
• Thermal decomposition without oxygen• dehydration of cellulose, decomposition of lignine, partial
oxidation• product: charcoal fuel with higher caloricity (about 95 %
carbon, the rest is water and ash)
Charcoal pile
Production of cellulose (pulp)
Pulp = technical cellulose
1. pulp-wood is chipped
2. chips are cooked in alkaline solution (NaOH+Na2S orCa(HSO3)2+SO2) at 150 ˚C and 6 hours
3. lignin and hemi-cellulose dissolve → cellulose remains
4. bleaching of cellulose by H2O2 or Cl2
Production of paper
1. pulp is grinded in water solution to suspension of cellulosefibres
2. addind of recycled paper, binder, filler, pigment….
3. processing on paper machine: from cellulose suspensionto dry paper
Fossile raw materialsfor organic chemistry
Crude oil: containes alkanes and cykloalkanes – liquidcertain amount of dissolved gasses: ethane, propane
important by-products of oil refining: asphalt
Natural gas and coal: has to be converted mixture of CO and H2→ „synthesis gas“ (syn-gas) → synthesis of other hydrocarbons (Fischer-Tropsch process)
important by-product of coking: tar
Asphalt
Black, sticky, viscous liquid or semi-solidRest after destilation of crude oil
Dispersion of two phases: maltenes liquid organic compounds (oil)M=500-1000 g/mol
Other use: binder of aggregates in road construction
Tarby-product of coal cokingliquid, black organic matter
hydrofobic: use for roofing shingles ,insulation tar paper
Synthetic polymers on C basis
Elastomers Plastomers
Elastic deformation Plastic deformation
Rubbers Thermoplastics
May be reversiblyformed by heating
Thermosettingplastics
After curing are notformable any more
General properties of polymers� physical and chemical properties depend on the chemical
composition (type of monomers), length of chains ,1D or 3D structure
� are easily formed and modified (e.g. increase adhesion)
� usually low price
� low heat resistance and flammability (not true for Teflon)
Higher stregth and stability
Structure of polymers
Monomer: principal, repeating unit
Molar mass of polymer: up to 300 000 g/mol
Degree of polymerization:
polymer
monomer
Mn
M=
Polyethylene
Structure of polymers 2
a) linear polymer
b) branch polymer
c) cross-linked polymer – 3D structure (rubber)
Formation of polymeric structure
a) polymerization joining of alkenes (double bond) to chain-no by-product-polymer has the same chemical composition as monomers
b) polycondensation joining of monomers by condensationby-product: water
c) polyaddition addition of monomer to a growing chain by-proper functional group-polymer contains the same elements as monomers,but in different possitions
Polymerization
Monomers have double bond – converts to a new bondbetween monomers → formation of polymer
Styrene (vinyl benzene) Poly-styrene
Mechanism of polymerization: monomer(s) are dissolvedin solution, polymerization takes place by radical, cationic oranionic mechanism