Vibrational Spectra of Poly(ethylene terephthalate) Chains in the Mesomorphic Form

Rizzo, Paola; Trotta, Diletta; Musto, Pellegrino; Guerra, Gaetano

doi:10.1002/macp.201700362

Cited by 4 publications

(3 citation statements)

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“…The procedure adopted to quantify X c is the well-established method of the spectral subtraction of the amorphous component: , where A D , A s , and A r represent, respectively, the difference, the sample, and the reference spectra and the subtraction factor, k , is adjusted so as to reduce to the baseline a specific signature of the reference spectrum (at 475 cm –1 , see Figure ). For the present case, the reference spectrum is that of the purely amorphous sample (i.e., the film prior to the sorption test) and A D ( v ) represents the spectroscopically purified crystalline phase.…”

Section: Resultsmentioning

confidence: 99%

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Benzene-Induced Crystallization of PPO: A Combined Thermodynamic and Vibrational Spectroscopy Study

Musto

Loianno

Scherillo

et al. 2019

Ind. Eng. Chem. Res.

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Sorption of benzene vapor in amorphous poly(2,6-dimethyl-1,4-phenylene) oxide (PPO) has been investigated experimentally at 40 °C by gravimetric analysis and in situ FTIR spectroscopy. This analysis indicates the occurrence of polymer crystallization during sorption when experiments are performed at elevated benzene activities. In fact, absorbed benzene determines a depression of the glass transition temperature of the system and, in turn, an increase of macromolecular mobility that promotes a solvent induced crystallization. The event of crystallization is evidenced by the presence of an overshoot in the sorption curve, both in gravimetric and spectroscopic sorption experiments performed at a relative pressure of benzene vapor close to 0.80. A theoretical approach, based on the combination of a nonrandom compressible lattice fluid theory and of the Gibbs−Di Marzio criterion, has been used to predict the glassy−rubbery state domain map of the PPO−benzene system, in temperature−benzene vapor pressure coordinates, showing that the system should display a retrograde vitrification phenomenon. This modeling allowed the identification of values of benzene vapor pressure favoring the occurrence of solvent induced crystallization that are consistent with the indications emerging from the gravimetric sorption isotherm. In addition, relevant insight into the crystallization process occurring during sorption has been obtained from vibrational spectroscopy, evidencing a rather peculiar behavior that points to the formation of cocrystalline benzene−PPO structures.

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Section: Resultsmentioning

confidence: 99%

“…The procedure adopted to quantify X c is the well-established method of the spectral subtraction of the amorphous component: 53,54…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Benzene-Induced Crystallization of PPO: A Combined Thermodynamic and Vibrational Spectroscopy Study

Musto

Loianno

Scherillo

et al. 2019

Ind. Eng. Chem. Res.

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“…Intriguingly, the terephthalic polyesters bearing shorter CH 2 segments ( e.g. , PET, PTT, and PBT) can form the unique mesophase when their amorphous samples are stretched at a low temperature around or below T g . ,− Such mesophase is characterized by a layered structure with longitudinal order, assigned to the long-range ordered smectic-like phase. , Two flat phenylene groups of PET, PTT, and PBT can have π–π interactions with each other, acting as the mesogenic units to induce the formation of long-range ordered mesophase . The periodicity and formation condition of the mesophase vary with the change of CH 2 segment length in terephthalic polyesters.…”

Section: Introductionmentioning

confidence: 99%

Temperature-Dependent Triple Crystal Polymorphism of Poly(hexamethylene terephthalate): Long-Range Ordered Mesophase Formation and Crystal Structure–Property Relationships

Xia,

Ni,

Zeng

et al. 2024

Macromolecules

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Terephthalic polyesters are important engineering plastics and can crystallize into multiple crystal phases, including the mesophase in processing. However, the formation process and structural characteristics for the unique long-range ordered mesophase of terephthalic polyesters are still not well understood. Herein, we investigated the crystal polymorphism, crystallization kinetics, phase transition, and mechanical properties of a medium-chain terephthalic polyester, poly(hexamethylene terephthalate) (PHT). A new long-range ordered mesophase (named as the δ phase) is discovered for PHT during quiescent melt crystallization at a low crystallization temperature (T c = 10−30 °C). However, the α and β crystal phases are crystallized at a medium (40−80 °C) and high (90−130 °C) T c , respectively. The mesomorphic δ phase has a long-range order with a layered structure and inclined chain packing, which shows faster chain relaxation and smaller lamellar thickness than the α and β phases. The mesomorphic δ phase is metastable and converts into the stable β phase upon heating or high-temperature annealing. Mechanical properties of PHT can be well tuned by crystal polymorphs. The mesomorphic δ phase of PHT has good transparency and ductility, while the α and β phases possess a higher yield strength and modulus. This work provides an in-depth understanding of the mesophase formation and complex crystal polymorphism of terephthalic polyesters.

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Polyethylene terephthalate (PET) optical properties deterioration induced by temperature and protective effect of organically modified SiO2–TiO2 coating

Szczurek

Tran

Kubacki

et al. 2023

Materials Chemistry and Physics

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Vibrational Spectra of Poly(ethylene terephthalate) Chains in the Mesomorphic Form

Cited by 4 publications

References 50 publications

Benzene-Induced Crystallization of PPO: A Combined Thermodynamic and Vibrational Spectroscopy Study

Benzene-Induced Crystallization of PPO: A Combined Thermodynamic and Vibrational Spectroscopy Study

Temperature-Dependent Triple Crystal Polymorphism of Poly(hexamethylene terephthalate): Long-Range Ordered Mesophase Formation and Crystal Structure–Property Relationships

Polyethylene terephthalate (PET) optical properties deterioration induced by temperature and protective effect of organically modified SiO2–TiO2 coating

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