Physical gelation and macromolecular mobility of sustainable polylactide during isothermal crystallization

2017 ◽  
Vol 55 (16) ◽  
pp. 1235-1244 ◽  
Author(s):  
Huagao Fang ◽  
Qizheng Xie ◽  
Haibing Wei ◽  
Pei Xu ◽  
Yunsheng Ding
Keyword(s):  
Isothermal Crystallization ◽  
Physical Gelation ◽  
Macromolecular Mobility

scholarly journals Non-Isothermal Crystallization Kinetics of Poly(Ethylene Glycol)–Poly(l-Lactide) Diblock Copolymer and Poly(Ethylene Glycol) Homopolymer via Fast-Scan Chip-Calorimeter

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1156
Author(s):  
Dejia Chen ◽  
Lisha Lei ◽  
Meishuai Zou ◽  
Xiaodong Li
Keyword(s):  
Ethylene Glycol ◽  
Heterogeneous Nucleation ◽  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Poly Ethylene Glycol ◽  
Ozawa Method ◽  
Isothermal Crystallization Kinetics ◽  
Fast Cooling ◽  
Poly Ethylene ◽  
Kinetics Of

The non-isothermal crystallization kinetics of double-crystallizable poly(ethylene glycol)–poly(l-lactide) diblock copolymer (PEG-PLLA) and poly(ethylene glycol) homopolymer (PEG) were studied using the fast cooling rate provided by a Fast-Scan Chip-Calorimeter (FSC). The experimental data were analyzed by the Ozawa method and the Kissinger equation. Additionally, the total crystallization rate was represented by crystallization half time t1/2. The Ozawa method is a perfect success because secondary crystallization is inhibited by using fast cooling rate. The first crystallized PLLA block provides nucleation sites for the crystallization of PEG block and thus promotes the crystallization of the PEG block, which can be regarded as heterogeneous nucleation to a certain extent, while the method of the PEG block and PLLA block crystallized together corresponds to a one-dimensional growth, which reflects that there is a certain separation between the crystallization regions of the PLLA block and PEG block. Although crystallization of the PLLA block provides heterogeneous nucleation conditions for PEG block to a certain extent, it does not shorten the time of the whole crystallization process because of the complexity of the whole crystallization process including nucleation and growth.

scholarly journals Shear-Induced and Nanofiber-Nucleated Crystallization of Novel Aliphatic–Aromatic Copolyesters Delineated for In Situ Generation of Biodegradable Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2315
Author(s):  
Ramin Hosseinnezhad
Keyword(s):  
Shear Rate ◽  
Cooling Rate ◽  
Isothermal Crystallization ◽  
Cellulose Nanofibers ◽  
Crystallization Time ◽  
Nucleation Density ◽  
Shear Rates ◽  
Biodegradable Nanocomposites ◽  
In Situ Generation

The shear-induced and cellulose-nanofiber nucleated crystallization of two novel aliphatic–aromatic copolyesters is outlined due to its significance for the in situ generation of biodegradable nanocomposites, which require the crystallization of nanofibrous sheared inclusions at higher temperatures. The shear-induced non-isothermal crystallization of two copolyesters, namely, poly(butylene adipate-co-succinate-co-glutarate-co-terephthalate) (PBASGT) and poly(butylene adipate-co-terephthalate) (PBAT), was studied following a light depolarization technique. To have a deep insight into the process, the effects of the shear rate, shear time, shearing temperature and cooling rate on the initiation, kinetics, growth and termination of crystals were investigated. Films of 60 μm were subjected to various shear rates (100–800 s−1) for different time intervals during cooling. The effects of the shearing time and increasing the shear rate were found to be an elevated crystallization temperature, increased nucleation density, reduced growth size of lamella stacks and decreased crystallization time. Due to the boosted nucleation sites, the nuclei impinged with each other quickly and growth was hindered. The effect of the cooling rate was more significant at lower shear rates. Shearing the samples at lower temperatures, but still above the nominal melting point, further shifted the non-isothermal crystallization to higher temperatures. As a result of cellulose nanofibers’ presence, the crystallization of PBAT, analyzed by DSC, was shifted to higher temperatures.

scholarly journals Thermal Properties, Isothermal Decomposition by Direct Analysis in Real-Time-Of-Flight Mass Spectrometry and Non Isothermal Crystallization Kinetics of Poly(Ethylene-Co-Vinyl Alcohol)/Poly(ε-Caprolactone) Blend

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 292
Author(s):  
Abdulaziz Ali Alghamdi ◽  
Hussain Alattas ◽  
Waseem Sharaf Saeed ◽  
Abdel-Basit Al-Odayni ◽  
Ahmed Yacine Badjah Hadj Ahmed ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Real Time ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Vinyl Alcohol ◽  
Time Of Flight ◽  
Direct Analysis ◽  
Isothermal Crystallization Kinetics ◽  
Flight Mass Spectrometry ◽  
Poly Ethylene

A series of poly(ethylene-co-vinyl alcohol)/poly(ε-caprolactone) blends with different compositions were prepared using solvent casting. The miscibility of this pair of polymers was investigated using differential scanning calorimetry (DSC), and proved by a negative Flory interaction parameter value calculated from the Nishi–Wang equation. The miscibility of this blend was also confirmed by scanning electronic microscopy (SEM). The thermal behaviors of the obtained materials were investigated by DSC, thermogravimetric analysis, and direct analysis in real-time–time-of-flight mass spectrometry and the results obtained were very relevant. Furthermore, the crystalline properties of the obtained materials were studied by DSC and X-ray diffraction where the Ozawa approach was adopted to investigate the non-isothermal crystallization kinetics. The results obtained revealed that this approach described the crystallization process well.

Association and physical gelation of ABA triblock copolymer in selective solvent

Polymer ◽  
2003 ◽  
Vol 44 (18) ◽  
pp. 5303-5310 ◽  
Author(s):  
Katsuhiro Inomata ◽  
Daisuke Nakanishi ◽  
Ai Banno ◽  
Eiji Nakanishi ◽  
Yosuke Abe ◽  
...  
Keyword(s):  
Triblock Copolymer ◽  
Selective Solvent ◽  
Physical Gelation ◽  
Aba Triblock Copolymer

scholarly journals Isothermal Crystallization Kinetics of Poly(ethylene oxide)/Poly(ethylene glycol)-g-silica Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 648
Author(s):  
Xiangning Wen ◽  
Yunlan Su ◽  
Shaofan Li ◽  
Weilong Ju ◽  
Dujin Wang
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Poly Ethylene Glycol ◽  
Isothermal Crystallization Kinetics ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Kinetics Of

In this work, the crystallization kinetics of poly(ethylene oxide) (PEO) matrix included with poly(ethylene glycol) (PEG) grafted silica (PEG-g-SiO2) nanoparticles and bare SiO2 were systematically investigated by differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM) method. PEG-g-SiO2 can significantly increase the crystallinity and crystallization temperature of PEO matrix under the non-isothermal crystallization process. Pronounced effects of PEG-g-SiO2 on the crystalline morphology and crystallization rate of PEO were further characterized by employing spherulitic morphological observation and isothermal crystallization kinetics analysis. In contrast to the bare SiO2, PEG-g-SiO2 can be well dispersed in PEO matrix at low P/N (P: Molecular weight of matrix chains, N: Molecular weight of grafted chains), which is a key factor to enhance the primary nucleation rate. In particular, we found that the addition of PEG-g-SiO2 slows the spherulitic growth fronts compared to the neat PEO. It is speculated that the interfacial structure of the grafted PEG plays a key role in the formation of nuclei sites, thus ultimately determines the crystallization behavior of PEO PNCs and enhances the overall crystallization rate of the PEO nanocomposites.

Isothermal crystallization behavior of poly(L-lactic acid)/organo-montmorillonite nanocomposites

2009 ◽  
Vol 30 (9) ◽  
pp. 1338-1344 ◽  
Author(s):  
Xiaoxiu Li ◽  
Jingbo Yin ◽  
Zhenyang Yu ◽  
Shifeng Yan ◽  
Xiaochun Lu ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Montmorillonite Nanocomposites
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