The melt grafting of acrylates onto LLDPE was investigated for monomers of GMA

HPMA

HEMA

EMA

MMA and HEA by Haake mixer.It is found that

the depolymerization would occur during the melt grafting process for the grafted acrylate oligomer chains when the temperature was higher than the ceiling temperature (Tc) of the grafted acrylate polymers

which induced the decrease in the grafting ratio of the acrylates.Tc varied with different molecular structures of acrylate monomers.The influence of the steric hindrance and the special interactions between monomers was discussed.For the monomers with hydroxyl groups (GMA

HPMA

HEMA

HEA)

the larger the steric hindrance is

the lower the reaction heat

which results in the lower ceiling temperature.The monomers of MMA and EMA have no hydroxyl groups

so the reaction heat is much lower

which results in the relatively low ceiling temperature than that with hydroxyl groups.The order of the ceiling temperatures was finally suggested:Tc(HEA) Tc(HEMA) Tc(HPMA)Tc(GMA) Tc(EMA

MMA).The solution polymerization in dichlorobenzene of the acrylate monomers was carried out respectively and the ceiling temperature ranges of different acrylate monomers were identified

which agreed well with the results of melt grafting.The styrene (St) was added as co-monomer to assist the grafting of acrylate monomers onto LLDPE

and the effect could be predicted by the Q-e rule.The grafting ratio of GMA

HPMA

MMA and EMA could be improved by adding St because they can copolymerize with St well and the depolymerization in melt grafting could be depressed even at high temperatures.