Correlation of Sequence Block Lengths and Degree of Randomness with Melt Rheological Properties in PET/PEN Blends

Khonakdar, Hossein Ali; Golriz, Mahdi; Jafari, Seyed Hassan; Wagenknecht, Udo

doi:10.1002/mame.200800298

Cited by 21 publications

(38 citation statements)

References 21 publications

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“…The observed behavior of the sequence length and the degree of randomness in this study are consistent with previous reports of the copolymerization of PET/PEN and PET/PBT …”

Section: Resultssupporting

confidence: 93%

Synthesis of statistical PET/PEN random block copolymers and their crystallizability in the bulk and at the surface

Shinotsuka

Assender

Claridge

2018

J of Applied Polymer Sci

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A series of PET/PEN copolyesters were synthesized by molten transesterification. The degree of randomness and the sequence length of the copolymers were determined by 1H NMR spectroscopy, and the changes in the bulk glass transition temperature (TgB), bulk crystallization temperature (TcB), and bulk melting temperature (TmB) were observed by DSC. A clear relationship was obtained between the observed enthalpy of melting (ΔHm) and degree of randomness (B), and TmB was suppressed for the midcompositions. As with their homopolymer counterparts, there was significant depression in crystallization temperature at the surface (TcS) of the random/block copolymers compared with the bulk, and so surface‐localized crystallization could be induced in spin‐coated thick films (thickness ranging from ca. 400 to 700 nm) by annealing at a temperature in which the surface region is mobile, but the bulk is not. The formation of these clear surface crystals allows the morphology to be directly imaged by AFM, and we observed that the crystallizability and the lamellar morphology of the surface crystals deviated from those of the original homopolymers, depending on the mixing ratio of PET/PEN and degree of randomness. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46515.

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“…The observed behavior of the sequence length and the degree of randomness in this study are consistent with previous reports of the copolymerization of PET/PEN and PET/PBT …”

Section: Resultssupporting

confidence: 93%

Synthesis of statistical PET/PEN random block copolymers and their crystallizability in the bulk and at the surface

Shinotsuka

Assender

Claridge

2018

J of Applied Polymer Sci

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“…By propagation of ester exchange reactions, the irregularity in the structure of blend chains enhances. Therefore, the more irregularity in the structure, the weaker the crystallization peak is .…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the disappearance of the crystallization peak in blends can be related to the inadequate crystallization time during cooling. Moreover, some portions of the chains, which are located near the crystalline units during the second heating cycle, result in slight mobility and transfer to crystalline units, causing the appearance of a small exothermic cold crystallization peak . The T cc and Δ H cc values of samples in which this behavior was detected are presented in Table .…”

Section: Resultsmentioning

confidence: 99%

Interrelationship of thermal and mechanical properties of poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate)/graphene nanocomposites

Ghadami

Ehsani

Khonakdar

2015

J Vinyl Addit Technol

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In the present work, attempts were made to investigate the thermal and mechanical properties of melt‐processed poly(ethylene terephthalate) (PET)/poly(ethylene 2,6‐naphthalate) (PEN) blends and its nanocomposites containing graphene by using differential scanning calorimetry and tensile test experimenting. The results showed that crystallinity, which depends on a blend ratio, completely disappeared in a composition of 50/50. By introducing graphene to PET, even in low concentrations, the crystallinity of samples increased, while the nanocomposite of PEN indicated reverse behavior, and the crystallinity was reduced by adding graphene. In the case of PET‐rich (75/25) nanocomposite blends, by increasing the nano content in the blend, the crystallinity of the samples was enhanced. This behavior was attributed to the nucleating effect of graphene particles in the samples. From the results of mechanical experiments, it was found in PET‐rich blends that by increasing the PEN/PET ratio, the modulus of samples decreased, whereas in the case of PEN‐rich blends, a slight increment of modulus is seen as a result of the increment of the PEN/PET ratio. The two contradicting behaviors were attributed to the reduction of crystallinity of PET‐rich blends by enhancement of PEN/PET ratio and the rigid structure of PEN chains in PEN‐rich blends. Unlike the different modulus change of PET‐rich and PEN‐rich blends, the nanocomposites of these blends similarly indicated an increment of modulus and characteristics of rigid materials by increasing the nano content. Furthermore, the same behavior was detected in nanocomposites of each polymer (PET and PEN nanocomposites). The alteration from ductile to rigid conduction was related to the impedance in the role of graphene plates against the flexibility of polymer chains and high values of graphene modulus. J. VINYL ADDIT. TECHNOL., 23:210–218, 2017. © 2015 Society of Plastics Engineers

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“…As discussed earlier, shifting of H (s) to the lower level could be related to dispersion of filler and also to the lower extent of trans-reactions in the blends nanocomposites via the presence of graphene [5,40]. The plasticizing effect of the nanographene leads to a reduction of relaxation time, further viscous motions, and declining elastic modulus [36,40,41] as is represented well in the modulus studied earlier.…”

Section: Relaxation Time Spectramentioning

confidence: 76%

A comprehensive study on morphological and rheological behavior of poly(ethylene terephthalate) and poly(ethylene‐2,6‐naphthalene) nanocomposite blends in presence of graphene

Ghadami

Ehsani

Khonakdar

2016

Vinyl Additive Technology

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This study is concerned with morphological and rheological behavior of several systems based on poly(ethylene terephthalate) (PET), poly(ethylene-2,6-naphthalene) (PEN), PET/PEN blend, and their graphene-filled nanocomposites. The composites were prepared by using a melt-mixing method and analyzed by scanning electron microscopy and transmission electron microscopy techniques. It was observed that the graphene nanosheets were almost distributed uniformly, especially in the blend matrix. The applied mixing method was easily able to disperse nanographene as well as the initial aggregates in polyester and the blend system. By performing rheological examinations, the elastic modulus, viscosity, loss curve, and relaxation spectra of the samples were fully investigated. The presence of graphene had different effects on rheological properties such as viscosity and modulus in two polyester matrices and their blends. In all nanocomposite samples, with the addition of 1 wt% graphene, the elasticity level dropped relative to that of neat polyesters. In PEN nanocomposites, the tand peak appeared with the addition of graphene. However, in PET nanocomposites, the tand peak developed at higher frequency, with a low percentage of graphene nanosheets, and became narrower at greater quantity, compared with neat PET. By addition of nanographene into the blend, the damping factor increased. The relaxation spectra, H (s), helped to better understand the viscoelastic properties in the long-time region, and it was demonstrated that the graphene sheets retarded the relaxation process of polyesters in the molten state. The results of relaxation spectra and storage modulus agreed with each other, and similar trends were observed in all the samples under examination. J.

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Correlation of Sequence Block Lengths and Degree of Randomness with Melt Rheological Properties in PET/PEN Blends

Cited by 21 publications

References 21 publications

Synthesis of statistical PET/PEN random block copolymers and their crystallizability in the bulk and at the surface

Synthesis of statistical PET/PEN random block copolymers and their crystallizability in the bulk and at the surface

Interrelationship of thermal and mechanical properties of poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate)/graphene nanocomposites

A comprehensive study on morphological and rheological behavior of poly(ethylene terephthalate) and poly(ethylene‐2,6‐naphthalene) nanocomposite blends in presence of graphene

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