End group analysis is the most important absolute method of obtaining number-average molar mass values for polymers of the step-growth polymerization type. It is shown that large differences may arise between the value determined by titration and the actual amino end group content.
How end groups of polymer affects viscosity?
The polymer viscosity increases when the polymer concentration increases, as shown in Figure p27. Polymers with a higher molecular weight provide higher viscosity, as shown in Figure p28.
What is at the end of a polymer chain?
A method of termination that applies to all polymer reactions is the depletion of monomer. In chain growth polymerization, two growing chains can collide head to head causing the growth of both of the chains to stop.
How is the end group analysis done for Peg?
The analysis involves an indirect titration procedure. An excess of PMDA is mixed with the weighed PEG sample, and the catalyst is added.
Which reagent is used for end group analysis?
thiocarbonate
What is number average degree of polymerization?
The number-average degree of polymerization is a weighted mean of the degrees of polymerization of polymer species, weighted by the mole fractions (or the number of molecules) of the species. It is typically determined by measurements of the osmotic pressure of the polymer.
How is degree of polymerization measured?
Divide the molecular weight of the polymer by the molecular weight of the monomer unit to calculate the degree of polymerization. If the molecular mass of tetrafluoroethylene is 120,000, its degree of polymerization is 120,000 / 100 = 1,200.
How can you increase the degree of polymerization?
Increasing the degree of polymerisation. The strength properties of polymers increase with the length of the chains, which is controlled by the degree of polymerisation. For example, the tensile strength of polyethylene is directly related to the chain length, which is defined by the molecular weight (MW).
What is called the polymer in which degree of polymerization is less than 25?
Copolymer
How many types of polymerization degrees are there?
The Degree of Polymerization is classified in two forms, the number-average degree of polymerization and weight-average degree of polymerization.
What is degree of polymerization of cellulose?
Degree of polymerization (DP) is one of the most important structural properties of cellulose. The alkaline extraction can remove most of the hemicellulose and the rest of lignin, which can provide an accurate result of cellulose DP.
What is cellulose made of?
Cellulose is a long-chain polymer of glucose molecules joined together. As the plant adds one glucose molecule to the polymer, one molecule of water is released. You can see this mechanism in the video opposite. Cellulose polymerisation occurs as a plant grows and creates new cells.
What are types of polymerization?
There are two general types of polymerization reactions: addition polymerization and condensation polymerization. In addition polymerization, the monomers add to one another in such a way that the polymer contains all the atoms of the starting monomers.
What is polymerization process?
Polymerization, any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer. The monomer molecules may be all alike, or they may represent two, three, or more different compounds.
What is polymerization class 10th?
Polymerization is the process of connecting these monomers together and creating large macromolecules of different sizes and shapes. Polymerization is similar to constructing a large building out of the same type of Lego blocks.
What is polymerization give example?
A polymer is a large single chain-like molecule in which the repeating units derived from small molecules called monomers are bound together. The process by which monomers are transformed into a polymer is called polymerisation. For example ethylene polymerizes to form polyethylene.
What is a polymer used for?
Uses of polymers Polymers are used in almost every area of modern living. Grocery bags, soda and water bottles, textile fibers, phones, computers, food packaging, auto parts, and toys all contain polymers. Even more-sophisticated technology uses polymers.
