On the kinetics of isothermal crystallization of branched polyethylene

Strobl, G.; Engelke, T.; Maderek, E.; Urban, Günter

doi:10.1016/0032-3861(83)90175-1

Cited by 30 publications

(16 citation statements)

References 11 publications

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“…The overall crystallinity, defects, and crystal size distribution were determined by both SCBD and cooling rate [31]. Strobl and coworkers [32, 33] also investigated the effect of molecular weight and branches on the isothermal crystallization of some commercial low‐density polyethylene (LDPE) samples. They discovered that the crystallization behavior of LDPE was significantly affected by the chain branches.…”

Section: Introductionmentioning

confidence: 99%

Effect of long chain branching on nonisothermal crystallization behavior of polyethylenes synthesized with constrained geometry catalyst

Yang

Wang

et al. 2011

Polymer Engineering & Sci

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Nonisothermal crystallization behavior of linear and long chain branched (LCB) polyethylene (PE) samples having similar molecular weight but different long‐chain branching densities (LCBD) up to 0.44 C per 1000 carbons was investigated using differential scanning calorimetry (DSC) at various scanning rates. The LCB PE samples were prepared in our high‐temperature, high‐pressure continuous stirred‐tank reactor (CSTR) system using the constrained geometry catalyst. The existence of LCB was found to affect the PE crystallization behavior considerably. The enthalpy of crystallization and the ultimate degree of crystallinity decreased with the increase of LCBD. At the relatively low cooling rates, the small amount of LCB promoted nucleation but restrained chain movement and reduced the crystal growth rate. There was ∼ 17% of crystallinity generated from a secondary crystallization. The energy barrier became significant with the LCB structure, resulting in chain diffusion limitations and lower LCB PEs overall crystallization rates than their linear counterpart. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

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Section: Introductionmentioning

confidence: 99%

Effect of long chain branching on nonisothermal crystallization behavior of polyethylenes synthesized with constrained geometry catalyst

Yang

Wang

et al. 2011

Polymer Engineering & Sci

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“…Given a constant lamellar thickness and assuming a constant density difference G-0a, the differences in crystallinity between the fractions (table 2) must be due to differences in the specific internal surface with w,: volume fraction crystallinity. We were led to a similar view in a recent SAXS-study on the crystallization kinetics [12] which showed that the crystal thickness d c and the crystalline density Qc are constant. One has to note that L specifies the most probable distance between adjacent lamellae rather than an average value.…”

Section: Discussionmentioning

confidence: 65%

Crystallization and melting of fractions of branched polyethylene

Maderek

Strobl

1983

Colloid & Polymer Sci

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Effects of the molecular weight on the crystallization behaviour of branched polyethylene become observable if isothermal crystallization is studied at temperatures near to the melting end. Crystallinifies decrease with decreasing molecular weight. Thicknesses of lamellae grown during isothermal crystallization are independent of the molecular weight. They depend only on temperature. Compared to the effect of the branches polydispersity gives only a minor contribution to the broadening of the crystallization and melting range of low density polyethylene.

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“…In similar system of PEH/PEB ¼ 50/50, we have observed both fibril and isolated lamella crystal habits using atomic force microscopy [5]. Strobl et al insisted that a crystallization process of branched polyethylene was dendritic growth due to decreasing the specific internal surface from their studies of small Avrami exponent [27,28]. However, in PEH/PEOC blends, the diffusion process of PEOC chain from the growth front is the dominant effect on decreasing the Avrami exponent.…”

Section: Resultsmentioning

confidence: 89%