Multifunctional assumption

Although quantitative areas for all absorptions can not be obtained from a single spectrum, an assumption that a —C=0 group adjacent to a C=C bond has similar relaxation times, and hence they have comparable peak, area is made. Based on this assumption the conversion of various multifunctional monomers, which yield highly crosslinked polymers with methyl methacrylate, is determined from the spectra recorded at 1 ms contact time. It is also found that the conversion of these comonomers increases with the increasing length and flexibility of the spacer between the methacrylate double bonds 245). 

The molecular size distributions for multifunctional polymerization leading to three-dimensional polymers are derived in a manner analogous to those for linear polymers, but with much more difficulty. The derivations have been discussed elsewhere [1,15,19], and only the results will be considered here. The results given below are based on three simplifying assumptions of ideal network formation (1) all functional groups of the same type are equally reactive (2) all groups react independently of one another and (3) no intramolecular reactions (cyclization) occur. 

Thus this case study focuses on key methodological steps for handling a multifunctional system and the assumptions made when conducting the LCIs. Additionally, it discusses the effect of the type of the LCA studies, namely, prospective and retrospective, on the selection of the allocation methods and therefore on the LCA metrics. According to some researchers [72], attributional LCA requires market-oriented allocation while consequential appHcations require system expansion. However, it has also been reported that various allocation methods have been appUed in practical applications, depending on the goal and scope of the study and the LCA practitioner preference and expert knowledge [66]. 

Under the assumption of bimolecular termination, the reaction diffusion parameter R (equation (4.2)) was determined for the bulk photopolymerization of multifunctional (meth)acrylates [I, 3, 6, 17, 481. It was found that for methacrylates at the plateau level, R was in the order of 2 1 moP [6] and for acrylates R was 3-5 1 moP [I7J. In general, reduction of network cross-linking density by co-polymerization with a difunctional reactive diluent (2-hydroxyethyl methacrylate (HEMA), octyl methacrylate) [3] increased the values of R due to increased mobility of the polymerization system until a plateau is reached. The addition of an inert diluent (polyethylene glycol 400 (PEG 400) [3, 6] or hydrogenated monomers [25. 53]) to a flexible monomer of low viscosity did not change R,... 

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