scholarly journals Melting temperature versus crystallinity: new way for identification and analysis of multiple endotherms of poly(ethylene terephthalate)

2020 ◽  
Vol 27 (12) ◽  
Author(s):  
Ferenc Ronkay ◽  
Béla Molnár ◽  
Dóra Nagy ◽  
Györgyi Szarka ◽  
Béla Iván ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Crystallization Temperature ◽  
Ethylene Terephthalate ◽  
Primary Crystallization ◽  
Crystallization Time ◽  
X Ray Diffraction ◽  
Molecular Weights ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Peak Set

AbstractPoly(ethylene terephthalate) (PET) materials with different molecular weights were isothermally crystallized from melt by systematically varying the temperature and duration of the treatment performed in the differential scanning calorimeter (DSC). Multiple endotherm peaks were observed on the subsequent heating thermograms that were separated from each other on the basis of their melting temperature versus crystallization temperature and melting temperature versus crystallinity function. By this new approach five sub-peak sets were identified and then comprehensively characterised. Wide-Angle X-Ray Diffraction (WAXD) analyses revealed that the identified sub-peak sets do not differ in crystalline forms. By analysing the crystallinity and the melting temperature of the sub-peak sets as a function of crystallization time, crystallization temperature and intrinsic viscosity, it was concluded that below the crystallization temperature of 460 K the sub-peak sets that were formed during primary or secondary crystallization transform partially or completely to a third sub-peak set during the heating run of the measurement, while above this temperature, the sub-peak set formed during primary crystallization gradually transforms to a more stable structure, with higher melting temperature. These formations and transformations are described with mathematically defined parameters as well.

The Melting Behavior of Poly(Ethylene Terephthalate)/ Attapulgite Nanocomposites

2013 ◽  
Vol 773 ◽  
pp. 530-533
Author(s):  
Chen Liu ◽  
Xiang Hui Lu ◽  
Xue Qi ◽  
Peng Li
Keyword(s):  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Ethylene Terephthalate ◽  
Melting Process ◽  
Melting Behavior ◽  
Crystallization Time ◽  
Scanning Calorimetry ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Crystallization From The Melt

The melting and recrystallization behavior of Poly(ethylene terephthalate) (PET)/ Attapulgite(At)nanocomposites after isothermal crystallization from the melt was studied by Step-scan differential scanning calorimetry (SDSC). The influence of At contents, crystallization temperature and crystallization time on the melting process were examined. Two melting endotherms(in the SDSC CP.A curves, reversible part) and one recrystallization exotherm (in the SDSC CP.IsoK curves, irreversible part)of PET/At nanocomposites after isothermal crystallization were observed during the melt process. This ascribes to the melting-recrystallization mechanism .The low temperature endotherm attributes to the melting of primary crystal formed during the isothermal treating and the high temperature endotherm resulting from the melting of recrystallization materials. The reason why more recrystallization happened with the increase of At content was given and the process of recrystallization was described in detail. The effects of crystal perfection and recrystallization were minimized by increasing of crystallization temperature and time.

The Melting and Recrystallization Behavior of Poly(ethylene Terephthalate)/SiO2 Nanocomposites Studied by Step-Scan DSC

2009 ◽  
Vol 87-88 ◽  
pp. 69-73
Author(s):  
Chen Liu ◽  
Kang Zheng ◽  
Xia Yin Yao ◽  
Xian Zhang ◽  
Xiang Lan Liu ◽  
...  
Keyword(s):  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Ethylene Terephthalate ◽  
Melting Process ◽  
Crystallization Time ◽  
Recrystallization Behavior ◽  
Scanning Calorimetry ◽  
Poly Ethylene Terephthalate ◽  
Sio2 Nanocomposites ◽  
Poly Ethylene

The melting and recrystallization behavior of Poly(ethylene terephthalate) (PET)/SiO2 nanocomposites after isothermal crystallization from the melt was studied by Step-scan differential scanning calorimetry (SDSC). The influence of SiO2 contents, crystallization temperature and crystallization time on the melting process were examined. Two melting endotherms(in the SDSC CP.A curves, reversible part) and one recrystallization exotherm (in the SDSC CP.IsoK curves, irreversible part)of PET/SiO2 nanocomposites after isothermal crystallization were observed during the melt process. This ascribes to the melting-recrystallization mechanism .The low temperature endotherm attributes to the melting of primary crystal formed during the isothermal treating and the high temperature endotherm resulting from the melting of recrystallization materials. The reason why more recrystallization happened with the increase of SiO2 content was given and the process of recrystallization was described in detail. The effects of crystal perfection and recrystallization were minimized by increasing of crystallization temperature and time.

Modifying the surface of poly(ethylene terephthalate) nanofibrous materials by alkaline treatment and TiO2 nanoparticles

2017 ◽  
Vol 47 (8) ◽  
pp. 1944-1958 ◽  
Author(s):  
Ali Karimi ◽  
Hossein Izadan ◽  
Akbar Khoddami ◽  
Seyed A Hosseini
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Alkaline Hydrolysis ◽  
Ethylene Terephthalate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Poly Ethylene Terephthalate ◽  
Dye Absorption ◽  
Poly Ethylene ◽  
Scanning Electron

The mutual effects of nano-TiO2 and alkaline hydrolysis on the morphology, chemical structure, water absorption, and the dyeing behavior of poly(ethylene terephthalate) nanofibers were investigated via employing scanning electron microscope, Fourier Transform Infra Red Spectroscopy (FTIR) and X-ray diffraction, and measuring water contact angle, 3M repellency, and dye absorption. A direct relation between the alkaline hydrolysis rate and nanofibers hydrophilicity was observed, while the addition of the nano-TiO2 led to more hydrophobicity. However, the alkaline hydrolysis had the prominent effect. FTIR spectra illustrated no chemical interaction between the nanoparticles and nanofibers. It was also shown that the dye absorption at dyeing equilibrium and the rate of dyeing were increased by the presence of the nano-TiO2 and these effects were intensified by the alkaline hydrolysis. These observations were related to the reduction in the nanofibers diameter and the increase in the surface roughness, as evidenced in the scanning electron microscope, and the increase in the amorphous regions of the nanofibers, as shown by the X-ray diffraction diffractograms.

In Situ High Temperature X-Ray Diffraction Studies of Modified Poly(Ethylene Terephthalate)

1992 ◽  
Vol 36 ◽  
pp. 379-386
Author(s):  
T. Blanton ◽  
R. Seyler
Keyword(s):  
High Temperature ◽  
Ethylene Terephthalate ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Pet Crystallization

The effect of dimethyl-5-sodiosulfoisophthalate, SIP, on poly(ethylene terephthalate), PET, crystallization has been studied using in situ high-temperature x-ray diffraction, HTXRD. At low levels of SIP modification, PET-like crystallinity was observed. At high SIP levels, clustering of polyester ionomers was observed and crystallization was significantly suppressed. The HTXRD data along with differential scanning calorimetry, DSC, and small angle x-ray scattering, SAXS, indicate that the change from bulk crystallization to bulk ionomer formation occurred when 8-12 mol% of the diester linkages contained SIP.

scholarly journals Isothermal Crystallization Kinetics of Poly(ethylene terephthalate) Copolymerized with Various Amounts of Isosorbide

2020 ◽  
Vol 10 (3) ◽  
pp. 1046 ◽  
Author(s):  
Nicolas Descamps ◽  
Florian Fernandez ◽  
Pierre Heijboer ◽  
René Saint-Loup ◽  
Nicolas Jacquel
Keyword(s):  
Isothermal Crystallization ◽  
Ethylene Terephthalate ◽  
Systematic Investigation ◽  
Crystallization Time ◽  
Isothermal Crystallization Kinetics ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Half Crystallization Time ◽  
First Time ◽  
Kinetics Of

Poly(ethylene-co-isosorbide terephthalate) (PEIT) copolyesters could be used in various applications depending on their ability to crystallize. Moreover, the possibility to carry out solid-state post-condensation (SSP) is conditioned by its ability to sufficiently crystallize. The present study, thus, gives a systematic investigation of isothermal crystallization of these statistical copolyesters with isosorbide contents ranging from 4.8 to 20.8 mol.%. For each copolyester composition, the lowest isothermal half crystallization times and the highest Avrami constant (K) were obtained around 170 °C. Over the range of composition that was studied, both melting points and melting enthalpies decreased with increasing amounts of isosorbide (from 250 to 207 °C and from 55 to 28 J/g, respectively). On the contrary, half crystallization time displayed an exponential increase when increasing isosorbide contents in the studied range. Finally, structural and thermal analysis of PIT homopolyester are reported for the first time, showing that only ET moieties crystallized when PEIT was subjected to isothermal crystallization at 170 °C.

Sign in / Sign up

Export Citation Format

Share Document