Chain transfer to monomer
WebThe amount of chain transfer to monomers is usually small because this reaction requires breaking strong carbon-carbon or carbon-hydrogen bonds. 1 Thus. 1 / DP ≈ 1 / DP 0 + … WebWhile the basic free radical polymerization reactions of initiation, propagation, termination, and chain transfer are still favored, the secondary reactions begin to have a stronger impact on polymerization as the temperature rises. ... Secondary reactions significantly affect reaction kinetics in the polymerization of acrylate monomers ...
Chain transfer to monomer
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WebJan 1, 2013 · The cationic polymerization is a chain polymerization that involves three steps: (1) initiation, (2) propagation, and (3) termination. The feasibility of polymerization depends on the ease of cation formation from monomer. The reaction can occur with the addition of the electrophile (carbocation) to monomer and form more stable intermediate. WebFeb 5, 2024 · Saturated chain ends, instead, usually derive from chain transfer to a main group metal cocatalyst (e.g., Al and Zn alkyls) [31,32] or reaction with molecular …
WebJun 16, 2024 · Chain transfer to monomer is relatively low for many monomers but high for those with labile C–H bonds (e.g., vinyl acetate in which abstraction of a H atom from the ester methyl group gives a radical stabilized by resonance with the carbonyl group). The extent of chain transfer to solvents varies massively dependent upon the chemical ... http://willson.cm.utexas.edu/Teaching/Chem367L392N/Files/Lecture%2011.pdf
WebWith moderately hydrophobic chain transfer agents (i.e., mainly soluble in the monomer phase but sufficiently water soluble to diffuse from the monomer droplets to the particle, through the aqueous phase) exhibiting low chain transfer constant like dithiocarbonate (also called xanthates), the nucleation step was not modified with respect to a … WebJan 31, 1998 · The monomer chain transfer constant (C M) has been evaluated for three monomers in bulk polymerization, viz, methyl methacrylate (MMA), styrene (STY) and α …
WebJul 23, 2008 · Computational studies of a variety of polymerization catalyst models have revealed an unexpected fluidity in chain termination mechanisms. For many early transition metal olefin polymerization catalysts two distinct transition states exist for β-hydrogen transfer to monomer, which differ mainly in the M−H distance and CMC angle. The …
http://www.polymerdatabase.com/polymer%20chemistry/Chain%20Transfer.html 01班01牙Web2 days ago · Thermosetting materials generated by photopolymerization are inherently highly crosslinked and suffer from significant shrinkage stress, are often brittle, and have a limited range of mechanical properties. Various classes of chain transfer agents (CTAs) have been investigated and developed to reduce the crosslinking density of … 01玻璃WebJul 23, 2008 · Computational studies of a variety of polymerization catalyst models have revealed an unexpected fluidity in chain termination mechanisms. For many early … 01琴WebSep 12, 2024 · This unusual hydride transfer is probably facilitated by very close contact distance between two chains, or between two segments of one chain, in a concentrated polymerization milieu. As a result, one chain end stops growing, and the chain begins growing from a new position along its backbone. 01甜點工作室WebJan 28, 2024 · 31.1: Chain-Growth Polymers. Polymers resulting from additions to alkenes monomers are chain-growth polymers. In these processes each addition step results in … 01理論Webchain branching through the terminal double bond propagation reaction. •Chain transfer to chain transfer agent R• n +S −→kfs P n +R • 1 r =k fsR• n S A chain transfer agent, S is a molecule containing a weak bond that can be broken to lead to radical transfer, similarly as in the case of monomer above (e.g. CCl 4, CBr 4, mercaptans). 01生命