Nonisothermal crystallization kinetics of low‐density polyethylene inside percolating network of ZnO nanoparticles

Abstract

The nonisothermal crystallization of lowdensity polyethylene inside percolating network of ZnO nanoparticles (LDPE/60 vol % ZnO) was investigated via differential scanning calorimetry (DSC), and compared to that of LDPE bulk (pristine LDPE and LDPE/1.15 vol % ZnO). The results revealed that crystallization behavior of LDPE inside ZnO percolating network was quite different from that of LDPE bulk. The former showed $ 4 C higher crystallization onset temperatures contrasting to the latter, demonstrating nucleation effect of ZnO on LDPE crystallization. On the other hand, much longer half-crystallization times were observed for the former, illustrating that crystallization of LDPE is retarded by the continuous ZnO net-work to some extent. Moreover, LDPE embedded inside ZnO network has by far larger crystallization activation energy and smaller specific free energy of the folding surface in contrast to LDPE bulk. Finally, nonisothermal crystallization kinetics study illustrated that both modified Avrami and Liu methods could be used to describe satisfactorily nonisothermal crystallization kinetics for all the samples investigated. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 125: E113-E121, 2012

Nonisothermal crystallization of isotactic polypropylene in carbon nanotube networks

“…In each sample, the crystallization peak becomes wider and onset temperature (T 0 ) shifts to lower temperature with increasing cooling rate due to time-dependent nucleation and crystal growth, which is in agreement with many previous studies. [30][31][32] From these curves, some useful parameters such as the T 0 and T p , and the values of T 0 ÀT p of the samples can be obtained, as shown in Figure 4. It can be seen from Figure 4(a) that the T 0 of PPCN20 increases by more than 18 C compared to PP0 at all the cooling rates, indicating an appreciable heterogeneous nucleation effect of CNT network on iPP crystallization, which could be attributed to the easy attachment of iPP segments in melted state onto the surface of CNTs and subsequently the initiation of iPP nucleation at higher temperature.…”