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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 ...
The type I reaction dominates, which cause chain scission at the carbonyl unit to give a range of products. [1] [38] Type II Norrish reactions are less common but give rise to acetaldehyde by way of vinyl alcohol esters. [36] This has an exceedingly low odour and taste threshold and can cause an off-taste in bottled water. [39]
It is a colourless solid which is soluble in most common organic solvents, but has very poor solubility in water. [2] [7] BPA is produced on an industrial scale by the condensation reaction of phenol and acetone. Global production in 2022 was estimated to be in the region of 10 million tonnes. [8]
One important class of condensation polymers are polyamides. [4] They arise from the reaction of carboxylic acid and an amine. Examples include nylons and proteins.When prepared from amino-carboxylic acids, e.g. amino acids, the stoichiometry of the polymerization includes co-formation of water:
Polycarbonate polyols are more expensive than other polyols and are thus used in more demanding applications. [31] [32] They have been used to make an isophorone diisocyanate based prepolymer which is then used in glass coatings. [33] They may be used in reactive hotmelt adhesives. [34] All polyols may be used to produce polyurethane prepolymers.
The continuous water phase is an excellent conductor of heat, enabling fast polymerization rates without loss of temperature control. Since polymer molecules are contained within the particles, the viscosity of the reaction medium remains close to that of water and is not dependent on molecular weight.
When exiting a reactor after a polymerization reaction, many polymers still contain undesired low-molecular weight components. These component may make the product unusable for further processing (for example, a polymer solution cannot directly be used for plastics processing), may be toxic, may cause bad sensory properties such as an unpleasant smell or worsen the properties of the polymer.
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 .