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The main polycarbonate material is produced by the reaction of bisphenol A (BPA) and phosgene COCl 2. The overall reaction can be written as follows: The first step of the synthesis involves treatment of bisphenol A with sodium hydroxide, which deprotonates the hydroxyl groups of the bisphenol A. [6] (HOC 6 H 4) 2 CMe 2 + 2 NaOH → Na 2 (OC 6 ...
"Step growth polymerization" and condensation polymerization are two different concepts, not always identical. In fact polyurethane polymerizes with addition polymerization (because its polymerization produces no small molecules), but its reaction mechanism corresponds to a step-growth polymerization.
A polycarbonate is an oxocarbon dianion consisting of a chain of carbonate units, where successive carbonyl groups are directly linked to each other by shared additional oxygen atoms. That is, they are the conjugate bases of polycarbonic acids , the conceptual anhydrides of carbonic acid , or polymers of carbon dioxide .
The simplest case refers to the formation of a strictly linear polymer by the reaction (usually by condensation) of two monomers in equimolar quantities. An example is the synthesis of nylon-6,6 whose formula is [−NH−(CH 2) 6 −NH−CO−(CH 2) 4 −CO−] n from one mole of hexamethylenediamine, H 2 N(CH 2) 6 NH 2, and one mole of adipic acid, HOOC−(CH 2) 4 −COOH.
The total number of radicals delivered to the system by the initiator during the course of the polymerization is low compared to the number of RAFT agent molecules, meaning that the R group initiated polymer chains from the re-initiation step form the majority of the chains in the system, rather than initiator fragment bearing chains formed in ...
An example of chain transfer in styrene polymerization. Here X = Cl and Y = CCl 3. In some chain-growth polymerizations there is also a chain transfer step, in which the growing polymer chain RM n ° takes an atom X from an inactive molecule XY, terminating the growth of the polymer chain: RM n ° + XY → RM n X + Y°.
For example, if narrow molar mass distribution standards are available for polystyrene, these can be used to construct a calibration curve (typically vs. retention volume ) in eg. toluene at 40 °C. This calibration can then be used to determine the "polystyrene equivalent" molecular weight of a polyethylene sample if the Mark-Houwink ...
The application of the principle typically involves the following steps: experimental determination of frequency-dependent curves of isothermal viscoelastic mechanical properties at several temperatures and for a small range of frequencies; computation of a translation factor to correlate these properties for the temperature and frequency range