Search results
Results From The WOW.Com Content Network
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 ...
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 .
Phase I reactions occur by adding an oxygen to either of the benzene rings by Cytochrome P450. [49] The type of P450 present also determines where the oxygen will be added; phenobarbital (PB)-induced P450s catalyze oxygenation to the meta-para positions of PCBs while 3-methylcholanthrene (3MC)-induced P450s add oxygens to the ortho – meta ...
Photodissociation involves the formation of an excited terephthalic acid unit which undergoes Norrish reactions. 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]
Diverse methods are employed to manipulate the initiation, propagation, and termination rates during chain polymerization. A related issue is temperature control, also called heat management, during these reactions, which are often highly exothermic. For example, for the polymerization of ethylene, 93.6 kJ of energy are released per mole of ...
Thus, the measured viscosity of polymers can provide valuable information about the average length of the polymer, the progress of reactions, and in what ways the polymer branches. [11] Composites are formed by combining polymeric materials to form an overall structure with properties that differ from the sum of the individual components.
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:
Biology is thus but a branch of the physico-chemistry of liquids; it includes the study of electrolytic and colloidal solutions, and of the molecular forces brought into play by solution, osmosis, diffusion, cohesion, and crystallization."