Coagent-induced transformations of polypropylene microstructure: Evolution of bimodal architectures and cross-linked nano-particles

Control of degradation of polypropylene during its radical functionalisation with furan and thiophene derivatives

“…Therefore, the functionalisation as well as b-scission occur preferentially on high MW macro-radicals [24,26]. Consequently, combining the above considerations, whether the MAH grafted on the PP tertiary macroradicals at high MW chains or not, the formation of a considerable fraction of cut polymer chains occurs.…”

“…It has also to consider that the probability of hydrogen atom transfer is uniform between propylene mers (units), hence chains of higher MW have a larger reaction probability [26]. Therefore, the functionalisation as well as b-scission occur preferentially on high MW macro-radicals [24,26].…”

“…Most likely both b-scission and coupling reactions took place for this sample. The functionalizing molecules should be preferentially grafted to the high MW chains, since the radical activity it is reported to be more probable amongst the longest chains [24,26]. Hence, it is reasonable to believe that the PPBFA macro-radicals were involved in coupling reactions.…”

Combined effects between activating group Z and leaving group R in dithiocarbamates for controlling degradation and branching reactions of polypropylene

“…Previous researches have demonstrated that prolonging the life time of macroradicals by forming reversible dormant chains using thiuram disulfides [9] and metal dithiocarbamate [10,11] or stabilizing macroradicals by changing radical intermediate states using styrene [12] and furan derivatives [13e15] are efficient routes to reduce the chain scission and improve branching reaction. In addition, the homopolymerization of multifunctional monomers often occurs during preparing LCBPP [16,17], which leads to uneven reactions between primary radicals/macroradicals and multifunctional monomers, and even the formation of highly branched structures [16] or large gel aggregates [17] and lower branching efficiency of multifunctional monomers. However, there are few literatures concerning the reduction of the homopolymerization of multifunctional monomers and the promotion of the branching efficiency of multifunctional monomers [18].…”

“…On one hand, it is expected to design a specific dithiocarbamate which can better control the bscission of PP macroradicals and avoid severe degradation of PP backbone; on the other hand, the dithiocarbamate are expected to control the homopolymerization of multifunctional monomers to avoid the formation hyperbranched structure [16] or large gel [17] and thus improve the efficiency of multifunctional monomers to form LCB structures.…”