Introduction to Polymer Crystallization

Nurazzi, Norizan Mohd; Norrrahim, Mohd Nor Faiz; Shazleen, Siti Shazra; Harussani, M.M.; Sabaruddin, Fatimah Athiyah; Asyraf, M. R. M.

doi:10.1002/9783527839247.ch1

Cited by 1 publication

(3 citation statements)

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“…Broadly, there exist two principal viewpoints. (1) The majority of authors attribute this signal to the presence of elliptical porous structures (cavities) within pure amorphous polymers or the amorphous phase of semicrystalline polymers. 8,18,47,48 The characterization of the dimensions, quantity, and volume fraction of these cavities can be assessed using (ultra-)SAXS techniques, for instance, as demonstrated by Mourglia-Seignobos et al, 47 Djukic et al, 48 and Charvet et al 49 (2) An alternate interpretation posits that this signal might stem from large-scale structural heterogeneity within the lamellar stacks along the tensile direction.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Semicrystalline polymers comprise more than two-thirds of all polymeric materials in industrial applications. 1 They exhibit a naturally composite structure, which allows them to combine the advantageous properties of both crystalline and amorphous phases. At the nanoscale of semicrystalline polymers, the fundamental building unit that accounts for the biphasic properties is the lamellar composite structure, which consists of a crystalline layer and an amorphous layer.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Semicrystalline polymers comprise more than two-thirds of all polymeric materials in industrial applications . They exhibit a naturally composite structure, which allows them to combine the advantageous properties of both crystalline and amorphous phases.…”

Section: Introductionmentioning

confidence: 99%

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What Determines Yield Stress in Semicrystalline Polymers within Lamellar Stack Dimensions: Competition between the Yield Behaviors of Crystalline and Glassy Amorphous Phases

Chen,

Zhu,

Zhang

et al. 2024

Macromolecules

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Through meticulous design involving prestretching and various annealing procedures, we prepared poly(ethylene terephthalate) (PET) films featuring a series-coupled lamellar composite model structure. Each film manifests distinct properties of the crystalline and glassy amorphous phases. Using synchrotronbased in situ small-angle X-ray scattering and wide-angle X-ray diffraction techniques, we investigated the yield mechanisms of these oriented PET samples. Our findings highlight a competition between the yield behaviors of the two phases. In PET samples exhibiting low crystallinity, thin and imperfect crystals, and limited chain mobility in the amorphous phase, it becomes evident that the yield of the crystalline phase significantly influences the macroscopic yield stress. For these samples, we observed a positive correlation between the yield stress and the cohesive strength of the crystalline structure (considering crystallinity, crystal thickness, and perfection), consistent with findings commonly reported in publications. However, an intriguing phenomenon emerged when PET samples underwent annealing at elevated temperatures, specifically at 230 °C for durations exceeding 10 min. In these treated samples, the yield of the amorphous phase emerged as the primary contributor to the macroscopic yield stress, exhibiting a surprising negative correlation between the cohesive strength of the crystalline structure and the macroscopic stress, which contradicts conventional wisdom.

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