Molecular structure development of metallocene‐catalyzed linear low density polyethylene under ultrasonic irradiation

Abstract

In this work, the effect of ultrasonic irradiation on molecular structure development of metallocene‐catalyzed linear low density polyethylene (mLLDPE) was studied. GPC results show that ultrasonic irradiation have influence on molecular weight and molecular weight distribution of mLLDPE. Molecular weight of mLLDPE decreases slightly at the initial 30 s of ultrasonic irradiation and then increases obviously; its distribution becomes wider with the increase of ultrasonic irradiation time. The power and frequency of ultrasonic irradiation have the distinct influence on molecular weight and its distribution of mLLDPE. DSC results show that ultrasonic irradiation has distinct influence on multiple step crystallizing behaviors of mLLDPE because of the change of branched chain in mLLDPE molecules. Thermal stability of mLLDPE is improved greatly because of micro‐crosslinking structure in mLLDPE molecule, which is formed in the presence of ultrasonic irradiation. A possible mechanism for molecular structure development of mLLDPE in the presence of ultrasonic irradiation is also proposed in this paper. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2121–2129, 2005

Effects of ultrasound vibration on the structure and properties of polypropylene/graphene nanoplatelets composites

“…Another thing should be noted is that all of the above phenomenon is more obvious in low shear rate than the high one. It is because the higher shear rate will decrease ultrasound treatment time, and then the effect of ultrasound vibration on PP/GNPs nanocomposites will be reduced [40]. This is also confirmed by the FESEM analysis.…”

“…Wu et al [40,44] draw a conclusion that ultrasound vibration might lead to the degradation of polymeric matrix, then reduced the thermal degradation temperature of composites. To have a better understanding of the thermal stability of PP/GNPs nanocomposites extruded with the ultrasound vibration.…”

Effects of ultrasonic oscillations on linear viscoelastic behaviors of metallocene‐catalyzed linear low density polyethylene and its blends with low density polyethylene

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