Process engineering

Hatfield, Eric

doi:10.1016/b978-0-8155-2021-4.10008-5

Cited by 1 publication

(2 citation statements)

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“…9 During the MDO process, the semicrystalline film is heated to a temperature close to the melting temperature of the polymer, and then it is uniaxially stretched at a draw ratio close to 10, or even more in some cases. 10 Finally, the film is thermally treated in order to lock the new properties obtained from the stretching. This process has been proven to have a strong effect on the microstructure transformation from spherulitic to fibrillar and 11 enhances barrier properties 9 and tensile strength at break.…”

Section: Introductionmentioning

confidence: 99%

“…This process has been proven to have a strong effect on the microstructure transformation from spherulitic to fibrillar and 11 enhances barrier properties 9 and tensile strength at break. 10 In the laboratory scale, it has been shown that by applying elongational flow with high strain rate to a supercooled melt at a temperature close to the melting point, not only morphology is affected, but kinetics as well, resulting in an increase of up to 6 orders of magnitude of the crystallization rate and in an ultrahigh performance. 12 In addition to imposed flow, temperature can also affect the mobility of the chains, their orientation, and straightening.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Temperature on Flow-Induced Crystallization of Isotactic Polypropylene: A Molecular-Dynamics Study

Sigalas,

Van Kraaij,

Lyulin

2023

Macromolecules

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Molecular-dynamics simulations are employed in order to study the flow-induced crystallization (FIC) of isotactic polypropylene from a supercooled state at different temperatures. The study found that FIC displayed the highest rate at a temperature range of T max = 330–360 K. By applying the mean first passage time method, the pre-nucleation, nucleation, and growth stages were successfully identified. The pre-nucleation stage was thoroughly examined, and multiple phenomena were observed, including unexpected strain hardening in the vicinity of T max and the formation of high ordering areas that acted as nuclei precursors with limited motion along the tensile direction. Additionally, a non-uniformly slowed segmental relaxation was noted, which suggested the existence of cooperative rearranging regions, the percolation of which could potentially explain the strain hardening effect. Furthermore, the size of the critical clusters at the nucleation point was independent of temperature. Finally, stable clusters grew and merged, resulting in the formation of a shish network.

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