scholarly journals Non-Isothermal Crystallization Kinetics of Poly(4-Hydroxybutyrate) Biopolymer

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2840 ◽  
Author(s):  
Ina Keridou ◽  
Luis J. del Valle ◽  
Lutz Funk ◽  
Pau Turon ◽  
Lourdes Franco ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cooling Rate ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Secondary Nucleation ◽  
Scanning Calorimetry ◽  
Limited Region ◽  
First Case ◽  
Biodegradable Poly ◽  
Insertion Mechanism

The non-isothermal crystallization of the biodegradable poly(4-hydroxybutyrate) (P4HB) has been studied by means of differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). In the first case, Avrami, Ozawa, Mo, Cazé, and Friedman methodologies were applied. The isoconversional approach developed by Vyazovkin allowed also the determination of a secondary nucleation parameter of 2.10 × 105 K2 and estimating a temperature close to 10 °C for the maximum crystal growth rate. Similar values (i.e., 2.22 × 105 K2 and 9 °C) were evaluated from non-isothermal Avrami parameters. All experimental data corresponded to a limited region where the polymer crystallized according to a single regime. Negative and ringed spherulites were always obtained from the non-isothermal crystallization of P4HB from the melt. The texture of spherulites was dependent on the crystallization temperature, and specifically, the interring spacing decreased with the decrease of the crystallization temperature (Tc). Synchrotron data indicated that the thickness of the constitutive lamellae varied with the cooling rate, being deduced as a lamellar insertion mechanism that became more relevant when the cooling rate increased. POM non-isothermal measurements were also consistent with a single crystallization regime and provided direct measurements of the crystallization growth rate (G). Analysis of the POM data gave a secondary nucleation constant and a bell-shaped G-Tc dependence that was in relative agreement with DSC analysis. All non-isothermal data were finally compared with information derived from previous isothermal analyses.

The effect of cooling rate on crystallization behavior and tensile properties of CF/PEEK composites

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guangming Dai ◽  
Lihua Zhan ◽  
Chenglong Guan ◽  
Minghui Huang
Keyword(s):  
Cooling Rate ◽  
Crystallization Temperature ◽  
Crystallization Behavior ◽  
Crystalline Polymer ◽  
Scanning Calorimetry ◽  
Nonisothermal Crystallization ◽  
Cooling Rates ◽  
Control Range ◽  
Temperature Range ◽  
Transverse Tensile

Abstract In this study, the differential scanning calorimetry (DSC) tests were performed to measure the nonisothermal crystallization behavior of carbon fiber reinforced polyether ether ketone (CF/PEEK) composites under different cooling rates. The characteristic parameters of crystallization were obtained, and the nonisothermal crystallization model was established. The crystallization temperature range of the material at different cooling rates was predicted by the model. The unidirectional laminates were fabricated at different cooling rates in the crystallization temperature range. The results showed that the crystallization temperature range shifted to a lower temperature with the increase of cooling rate, the established nonisothermal crystallization model was consistent with the DSC test results. It is feasible to shorten the cooling control range from the whole process to the crystallization range. The crystallinity and transverse tensile strength declined significantly with the increase of the cooling rate in the crystallization temperature range. The research results provided theoretical support for the selection of cooling conditions and temperature control range, which could be applied to the thermoforming process of semi-crystalline polymer matrixed composites to improve the manufacturing efficiency.

scholarly journals The effect of isothermal crystallization on mechanical properties of poly(ethylene 2,5-furandicarboxylate)

e-Polymers ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 1-11
Author(s):  
Wei Zhang ◽  
Qingyin Wang ◽  
Gongying Wang ◽  
Shaoying Liu
Keyword(s):  
Mechanical Properties ◽  
Intrinsic Viscosity ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Tensile Modulus ◽  
Optical Microscope ◽  
Crystallization Time ◽  
Scanning Calorimetry ◽  
Crystallization Properties ◽  
Poly Ethylene

Abstract The effects of isothermal crystallization temperature/time on mechanical properties of bio-based polyester poly(ethylene 2,5-furandicarboxylate) (PEF) were investigated. The intrinsic viscosity, crystallization properties, thermal properties, and microstructure of PEF were characterized using ubbelohde viscometer, X-ray diffraction, polarizing optical microscope, differential scanning calorimetry, and scanning electron microscopy. The PEF sample isothermal crystallized at various temperatures for various times was denoted as PEF-T-t. The results showed that the isothermal crystallization temperature affected the mechanical properties of PEF-T-30 by simultaneously affecting its crystallization properties and intrinsic viscosity. The isothermal crystallization time only affected the crystallization properties of PEF-110-t. The crystallinity of PEF-110-40 was 17.1%. With small crystal size, poor regularity, and α′-crystal, PEF-110-40 can absorb the energy generated in the tensile process to the maximum extent. Therefore, the best mechanical properties can be obtained for PEF-110-40 with the tensile strength of 43.55 MPa, the tensile modulus of 1,296 MPa, and the elongation at a break of 13.36%.

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.

scholarly journals An Investigation of the Effect of Chitosan on Isothermal Crystallization, Thermal Decomposition, and Melt Index of Biodegradable Poly(L-lactic acid)

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Yan-Hua Cai ◽  
Li-Sha Zhao
Keyword(s):  
Thermal Decomposition ◽  
Lactic Acid ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Decomposition Temperature ◽  
Temperature Zone ◽  
Melt Index ◽  
Analysis Instrument ◽  
Biodegradable Poly ◽  
Higher Temperature

Biodegradable chitosan (CS) was introduced into another biodegradable poly(L-lactic acid) (PLLA) to prepare the PLLA/CS composites, and the effect of CS on thermal behavior and melt index of PLLA was investigated using modern testing technologies including optical depolarizer, thermogravimetric analysis instrument, and melt index instrument. The relevant testing results showed that both crystallization temperature and CS concentration affected the isothermal crystallization behavior of PLLA. Compared to neat PLLA, thet1/2of PLLA/5% CS decreased from 2991.54 s to the minimum value 208.76 s at 105°C. However, thet1/2of PLLA/CS composites in high crystallization temperature zone was different from that in low crystallization temperature zone. The increase of CS concentration and heating rate made the thermal decomposition temperature of PLLA/CS composites shift to higher temperature. The melt index results indicated that 3% CS made the fluidity of PLLA become better.

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.

scholarly journals Non-isothermal crystallization behavior of biodegradable poly(butylene succinate-co-terephthalate) (PBST) copolyesters

2012 ◽  
Vol 16 (5) ◽  
pp. 1480-1483
Author(s):  
Jie Zhang ◽  
Fa-Xue Li ◽  
Jiang-Yong Yu
Keyword(s):  
Differential Scanning Calorimetry ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Lamellar Thickness ◽  
Scanning Calorimetry ◽  
Butylene Succinate ◽  
Butylene Terephthalate ◽  
Melting Curves ◽  
Biodegradable Poly

Non-isothermal crystallization and subsequent melting of biodegradable poly(bu-tylene succinate-co-terephthalate) copolyesters with different butylene terephtha-late contents were investigated by differential scanning calorimetry measurements. Differential scanning calorimetry crystallization curves revealed that butylene terephthalate contents of poly(butylene succinate-co-terephthalate) copolyesters had an identical effects on the onset, peak and final crystallization temperatures. Subsequent differential scanning calorimetry melting curves implied that both PBST-10 and PBST-70 copolyesters had the narrow distribution of lamellar thickness, while the PBST-50 copolyester showed much wider distribution.

scholarly journals Effect of Alkyl Chain Length in POSS Nanocage on Non-Isothermal Crystallization Behavior of PCL/Amino-POSS Nanocomposites

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1719 ◽  
Author(s):  
Fernández ◽  
Guzmán ◽  
Ramos ◽  
Fernández
Keyword(s):  
Size Distribution ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Crystallization Process ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
Degree Of Crystallinity ◽  
Polyhedral Oligomeric Silsesquioxanes ◽  
Scanning Calorimetry ◽  
Oligomeric Silsesquioxane

The study of the non-isothermal crystallization behavior of polymers is of great importance due to the effect of degree of crystallinity and crystallization process on the polymer properties. The effect of aminopropylisobutyl polyhedral oligomeric silsesquioxane (APIBPOSS) and aminopropylisooctyl polyhedral oligomeric silsesquioxane (APIOPOSS) on poly(ε-caprolactone) (PCL) crystallization is studied by differential scanning calorimetry (DSC) under non-isothermal conditions and polarized optical microscopy (POM). The crystallization kinetics is analyzed using the Avrami and Mo models, and effective activation energies are evaluated by the Friedman isoconversional method. The results show that the compatibility between polyhedral oligomeric silsesquioxanes (POSS) and PCL and POSS loading affect the crystallization process. A higher crystallization temperature, a narrower size distribution of crystallite, and a faster crystallization rate are obtained in the presence of all the studied contents of APIBPOSS and at lower contents of APIOPOSS. At APIOPOSS contents higher than 2 wt %, the crystallization temperature is lowered, the size distribution of crystallite is broadened, and the crystallization process is retarded. The presence of POSS leads to an increase in the number of nucleation sites, and a reduction in the size of the crystallite and the overall degree of crystallinity, as a result of the confinement of PCL chains caused by POSS nanoparticles.

Investigation of Nonisothermal Crystallization Behaviors of Poly and Silica Nanocomposites Using Differential Scanning Calorimetry

2005 ◽  
Vol 295-296 ◽  
pp. 39-44 ◽  
Author(s):  
Ling Xue Kong ◽  
Z. Peng
Keyword(s):  
Differential Scanning Calorimetry ◽  
Cooling Rate ◽  
Crystallization Temperature ◽  
Self Assembly ◽  
Degree Of Crystallinity ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
Nonisothermal Crystallization ◽  
Crystallization Behaviors ◽  
Silica Nanocomposites

Nonisothermal crystallization behaviors of PVA and poly (vinyl alcohol) and Silica (PVA/SiO2) nanocomposites prepared via a self-assembly monolayer (SAM) technique are investigated in this study. Differential scanning calorimetry (DSC) is used to measure the crystallization temperature and enthalpy of PVA and nanocomposites in nitrogen at various cooling rate. The results show that the degree of crystallinity of PVA and nanocomposites decreases when the SiO2 content increases but increases with an increasing cooling rate. The peak crystallization temperature decreases with an increasing cooling rate.

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