Polymerization Processes

Versatility of a succinimidyl‐ester functional alkoxyamine for controlling acrylonitrile copolymerizations

“…fAN,0 = 0.70 and 0.86) it is possible that the polymerization becomes heterogeneous and the AN-rich copolymer begins to precipitate out the solution. This has been reported elsewhere for AN polymerizations [47][48][49][50] . Finally, it should be noted that it is possible that other effects such as inhibition and autoinitiation could be occurring.…”

Versatility of a succinimidyl‐ester functional alkoxyamine for controlling acrylonitrile copolymerizations

“…fAN,0 = 0.70 and 0.86) it is possible that the polymerization becomes heterogeneous and the AN-rich copolymer begins to precipitate out the solution. This has been reported elsewhere for AN polymerizations [47][48][49][50] . Finally, it should be noted that it is possible that other effects such as inhibition and autoinitiation could be occurring.…”

Synthesis of polyols by anionic polymerization: determination of kinetic parameters of propylene oxide polymerization using caesium and potassium alcoholates

“…The GPC analyses (Fig 2) show that the polyols synthesized with caesium and with potassium are quasi‐monomodal; that is to say, they are polymers of narrow molecular mass distribution, as expected. This quasi‐monomodal distribution is achieved because in this living polymerization the initiation reaction is very fast, almost instantaneous, and the ion exchange reactions are also so fast that all the chains have the same probability of adding a new monomer unit and growing uniformly 20. As can be seen, all the samples exhibit a rather small secondary peak at lower molecular weights This secondary peak is associated with the allyl adduct formed in the side reaction,18 confirming that the polymerization of propylene oxide, whether caesium or potassium initiated, cannot be properly considered as ‘living’.…”

Some Factors Affecting the Molecular Weight Distribution (MWD) in Low Density Polyethylene Multizone Autoclave Polymerization Reactors

“…The instantaneous MWD for each zone can be calculated based on the work of Hamielec (which is useful only for linear chains) and then the total MWD can be obtained by summing the individual MWDs. The instantaneous weight‐MWD in the j th zone can be calculated from the corresponding polymer production rate in such reactor zone as Where w ( j , n ) and R D ( j , n ) are the weight fraction and production rate of chains of length n in the zone j , respectively.…”

Versatility of a succinimidyl‐ester functional alkoxyamine for controlling acrylonitrile copolymerizations

“…fAN,0 = 0.70 and 0.86) it is possible that the polymerization becomes heterogeneous and the AN-rich copolymer begins to precipitate out the solution. This has been reported elsewhere for AN polymerizations [47][48][49][50] . Finally, it should be noted that it is possible that other effects such as inhibition and autoinitiation could be occurring.…”

Synthesis of polyols by anionic polymerization: determination of kinetic parameters of propylene oxide polymerization using caesium and potassium alcoholates

“…The GPC analyses (Fig 2) show that the polyols synthesized with caesium and with potassium are quasi‐monomodal; that is to say, they are polymers of narrow molecular mass distribution, as expected. This quasi‐monomodal distribution is achieved because in this living polymerization the initiation reaction is very fast, almost instantaneous, and the ion exchange reactions are also so fast that all the chains have the same probability of adding a new monomer unit and growing uniformly 20. As can be seen, all the samples exhibit a rather small secondary peak at lower molecular weights This secondary peak is associated with the allyl adduct formed in the side reaction,18 confirming that the polymerization of propylene oxide, whether caesium or potassium initiated, cannot be properly considered as ‘living’.…”

Some Factors Affecting the Molecular Weight Distribution (MWD) in Low Density Polyethylene Multizone Autoclave Polymerization Reactors

“…The instantaneous MWD for each zone can be calculated based on the work of Hamielec (which is useful only for linear chains) and then the total MWD can be obtained by summing the individual MWDs. The instantaneous weight‐MWD in the j th zone can be calculated from the corresponding polymer production rate in such reactor zone as Where w ( j , n ) and R D ( j , n ) are the weight fraction and production rate of chains of length n in the zone j , respectively.…”

Versatility of a succinimidyl‐ester functional alkoxyamine for controlling acrylonitrile copolymerizations

“…fAN,0 = 0.70 and 0.86) it is possible that the polymerization becomes heterogeneous and the AN-rich copolymer begins to precipitate out the solution. This has been reported elsewhere for AN polymerizations [47][48][49][50] . Finally, it should be noted that it is possible that other effects such as inhibition and autoinitiation could be occurring.…”

Synthesis of polyols by anionic polymerization: determination of kinetic parameters of propylene oxide polymerization using caesium and potassium alcoholates

“…The GPC analyses (Fig 2) show that the polyols synthesized with caesium and with potassium are quasi‐monomodal; that is to say, they are polymers of narrow molecular mass distribution, as expected. This quasi‐monomodal distribution is achieved because in this living polymerization the initiation reaction is very fast, almost instantaneous, and the ion exchange reactions are also so fast that all the chains have the same probability of adding a new monomer unit and growing uniformly 20. As can be seen, all the samples exhibit a rather small secondary peak at lower molecular weights This secondary peak is associated with the allyl adduct formed in the side reaction,18 confirming that the polymerization of propylene oxide, whether caesium or potassium initiated, cannot be properly considered as ‘living’.…”

Some Factors Affecting the Molecular Weight Distribution (MWD) in Low Density Polyethylene Multizone Autoclave Polymerization Reactors

“…The instantaneous MWD for each zone can be calculated based on the work of Hamielec (which is useful only for linear chains) and then the total MWD can be obtained by summing the individual MWDs. The instantaneous weight‐MWD in the j th zone can be calculated from the corresponding polymer production rate in such reactor zone as Where w ( j , n ) and R D ( j , n ) are the weight fraction and production rate of chains of length n in the zone j , respectively.…”