What is Polymerization?
The transformation of Monomers into Polymers.
What are the two subclasses of Polymerization in both models?
Model 1:
chain growth polymerization
step growth polymerization
Model 2:
addition reaction
condensation reaction
Give the educt and the product structure of the Polyethylen polymerization
What is the difference between Polymerization by an addition reaction and a condensation reaction?
The addition reaction runs with no waste or byproduct, the condensation reaction splits of a part of the Monomer, which is called condensate (e.g. HCL for PA6,6)
Name four examples for the Polymerization addition reaction.
PE, PP, PVC, PMMA
Name four examples for the Polymerization condensation reaction.
PA, PET, PC, Polyesters
What are the possible products of the Polyethylen polymerization?
LDPE: Low density Polyethylene: Very branched structure -> low packing density
HDPE: High density Polyethylene: linear chains -> lead to denser packing
UHMWPE: Utra high molecular weight Polyethylene: very long Polymer chains
What is an Oligomer?
The intermediate step between Monomer and Polymer <=> a few joined Monomers
What is the difference between the chain growth polymerization and the step growth polymerization?
In chain growth polymerisation an existing chain can only enlarge itself by reacting with a monomer.
In step growth polymerization two existing chains can react with eachother.
What is isotactic, syndiotactic and atactic?
What is the tacticity in the following comercial Polymers?
PS
PP
PVC
PMMA
Polystyrene: atactic
Polypropylene: isotactic
Polyvinylchloride: atactic
Polymethylmethacrylate: atactic
What is meant by the process of Vulcanization?
network forming in elastomers by sulfur
What are the steps in chain polymerization?
Chain initiation
Chain propagation
Chain transfer or termination
What is a Homopolymer?
A Homopolymer is a polymer made up of the same repeat unit, which can include multiple monomers
What is a Copolymer?
A Polymer which has different repeat units, which can occur in different non regular distributions
What are the type of distributions of Copolymers?
Statistical Copolymers: distribution following statistical laws
Random Copolymers: repetition random
Alternating Copolymers:-A-B-A-B-A-B-A-B-A-B-A-B-A-B-
Block Copolymers:-A-A-A-A-A-A-A-A-A-B-B-B-B-B
Graft Copolymers:
Name 4 examples for products of the polycondesation reaction.
PA6, PA6.6, PET, PC
Describe the type of polymerization and polymerization process of PA6.6, on Cl basis.
Polycondensation:
Describe the type of polymerization and polymerization process of PA6.6, on hydroxide basis.
“Stealing” of Hydrogen atom from other acid
Joining of chains and seperation of H2O and H+
What are the steps of the PET synthesis?
Dimethyl terephtalate+2 ethylen glycol->(transesterification) bis-(2-hydroxyethyl)terphtalate+2 methanol->(at270°C) Polyethyleneterephtalate+ ethylen glycol
What are the uses and problems of polycarbonate?
Glas like properties, used for glasses, windows etc.
BPA and Phosgen as educt, which can be residually present and harmfull for health
How is Polycarbonate formed?
Phenol+Acetone->BPA
BPA+Phosgen->Polycarbonate
What are the advantages of Polyether Sulfone?
high glass transition temperature
High rigidity and thermal resistance
low price
What is characteristic for PEEK?
Polyether-ether ketone:
highest thermal resistance of a polymer
very high stiffness
100-130 €/kg
What are characteristics of Aramids? Give the IUPAC name.
Poly phenylene terephthalamide
High toughness fibre
cannot be processed as a bulk material
for high strength fibre production
High crystallinity
What are the characteristics of PAI?
Polyamide imide
Very stiff -> forming and polymerization simultainous
polycondensation with water byproduct
high heat and chemical resistance
in competition with metals
Give the structure of an imide group.
What are the two forms of imide polymers and which form is preferrable?
aromatic form has better properties
What is a source of the toughness of the Polyamid imids?
The difference in partial load leads to electric forces bonding the macromolecule and the macromolecules amongst eachother together.
Why need Polyamid imids to be softened and how is that achieved?
To increase fromability for production
copolymerisation with bisphenol A, which has more flexability:
How is the burnability of Polyamid imids?
Self estinguishing, by developing a oxygen blocking layer
What are the steps of ring opening polymerisation?
What is the structure of an amide group?
What is the driving force behing ring opening polimerization?
bond-bond strain
steric repulsion
What are the two types of ring opening Polimerization?
cationic ring opening polimerization
anionic ring opening polimerization
Describe the mechanism of ring opening polymerization for Polysiloxanes.
Hydroxide donates electron, which causes Si-O bond to break. The excess electrons are shifted to the more electro negative O. Now it can open itself new rings.
Describe the Ring opening of Caprolactam. What Polymer is being produced?
Nylon6
How does the Nylon6 Polymerization work after the first ring opening?
Which Polymers can be obtained by Ring opening Polymerization?
Nylon6, PLA, PCL, PEO, PPO
What defines the Vinyl Polymerization?
The Polymerisation via double C-C bonds.
What are the subclasses of the Vinyl Polimeritstation?
Free radical vinyl polimerization
Ionic polymerization
Anionic polymerization
Cationic polymerization
Ziegler-Natta polymerization
Metallocene catalysis polymerization
Which polymers can be produced by free radical vinyl polimerisation?
PS, PMMA, PVA, PVC, PTFE, PP, PE
How are intiator transformed into free radicals?
Explain on the example of BPO.
What are the main termination reactions in radical polymerisation?
Coupling:
Disproportionation:
How are which types of PP produced?
Isotactic & atactic PP with zieglar-natta polymerization
alternating isotactic and atactic blocks with metallocene catalyst. Leads to elastomer.
What are the characteristics of PTFE
polytetrafluoroethylen:
teflon
free radical vinyl polymerization
high temperature and oxidation resistance
low friction coefficient
What are the characteristics of PS
Polystyrene
cheap product
syndiotacticity possible by metallocene catalysis
What are the characteristics of PMMA
Polymethylmethacrylate
Replacement for glass due to similar refractory index
What are the characteristics of PVC
Polyvinylchloride
Used for pipes
free radical polymerization
toxic educt
What are the characterisitcs of PVAC
Polyvinylacetate
used for glues
How does anionic polymerization function?
A initiator falls apart into a positive and negative part. The negative part reacts with the monomers and split the double bonds until they are depleted.
How does Cationic Vinyl Polimerization function?
The intiator will react with the double bond to form a single bond of its own. This continues with the Carbon atoms.
For which Polymer is Cationic Polymerization mainly used comercially?
PiB = Polyisobutylene
What are the most common intiators for anionic and cathionic polymerization?
cathionic:
What is the major problem with the Cationic Polymerization?
The intiator can also terminate the reaction and the polimerization doesnt need to run linearly along the chain. (which leads to non linear makromolecules)
How does the Ziegler-Natta polymerization function?
Formation of Ti-Al complex
What are the major differences between the Ziegler-Natta and the Metallocene catalysis polymerization.
A different Catalyst
The ability to have blocks of certain orientation in the Metallocene process
narrow molecular weight distribution for the Metallocene catalyst
What is the urethane structure?
What is special about the structure of Polyurethane?
One unit of Polyurethane consists of the polymer polyethylenglycol and a rigid aromatic component
What is the relation between molecular weight and conversion percentage for Chain growth, living and step growth polymerization?
What are the characteristics of PLA?
Polylactide Acid
ring opening polymerization
Biodegreadable
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