Influence of molecular characteristics on overall isothermal melt-crystallization behavior and equilibrium melting temperature of syndiotactic polypropylene

Lactide-Caprolactone copolymer (LACL) was added to a Polylactide/Poly(ε-caprolactone) (PLA/PCL) blend as a compatibilizer through solution mixing and the casting method. The melt crystallization behavior and crystalline morphology of PLA, PLA/PCL, and PLA/PCL/LACL were investigated using differential scanning calorimeter (DSC) and polarized optical microscopy (POM), respectively. The temperature of the shortest crystallization time for the samples was observed at 105 °C. The overall isothermal melt crystallization kinetics of the three samples were further studied using the Avrami theory. Neat PLA showed a higher half-time of crystallization than that of the PLA/PCL and PLA/PCL/LACL blends, whereas the half-time of crystallization of PLA/PCL and PLA/PCL/LACL showed no significant difference. The addition of PCL decreased the spherulite size of crystallized PLA, and the nuclei density in the PLA/PCL/LACL blend was much higher than that of the PLA and PLA/PCL samples, indicating that LACL had a compatibilization effect on the immiscible PLA/PCL blend, thereby promoting the nucleation of PLA. The spherulites in the PLA/PCL and PLA/PCL/LACL blend exhibited a smeared and rough morphology, which can be attributed to the fact that PCL molecules migrated to the PLA spherulitic surface during the crystallization of PLA.

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Effect of Cellulose Nanocrystal on Crystallization Behavior of Poly(3–hydroxybutyrate–co–3–hydroxyvalerate)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.430-432.20 ◽

2012 ◽

Vol 430-432 ◽

pp. 20-23 ◽

Cited By ~ 4

Author(s):

Hou Yong Yu ◽

Zong Yi Qin

Keyword(s):

Heterogeneous Nucleation ◽

Crystallization Temperature ◽

Crystallization Behavior ◽

Crystallization Rate ◽

Kinetics Study ◽

Solvent Casting ◽

Melt Crystallization ◽

Casting Method ◽

Isothermal Crystallization Kinetics ◽

Biodegradable Nanocomposites

The biodegradable nanocomposites of poly (3–hydroxybutyrate–co–3–hydroxyvalerate) (PHBV) with different cellulose nanocrystals (CNCs) contents were prepared by a solvent casting method. The effects of CNCs on the crystallization behavior of PHBV were studied by DSC. The DSC results showed that compared to PHBV, the melt crystallization temperature increased to 92.3 °C for the nanocomposites with 10 wt. % CNCs, which indicated that the crystallization of PHBV became easier with the addition of CNCs. Moreover, the non–isothermal crystallization kinetics study illustrated that overall crystallization rate of PHBV in the nanocomposites was faster than that of neat PHBV, which should be attributed to the strong heterogeneous nucleation of CNCs.

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Evaluation of thermal degradation and melt crystallization behavior of taro mucilage and its graft copolymer with poly(lactide)

SN Applied Sciences ◽

10.1007/s42452-019-1490-4 ◽

2019 ◽

Vol 1 (11) ◽

Cited By ~ 1

Author(s):

Abubakar Hamisu Mijinyawa ◽

Geeta Durga ◽

Anuradha Mishra

Keyword(s):

Thermal Degradation ◽

Graft Copolymer ◽

Crystallization Behavior ◽

Melt Crystallization

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Crystallization Behavior of Polypropylene/Syndiotactic1,2-Polybutadiene Blends

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.531-532.182 ◽

2012 ◽

Vol 531-532 ◽

pp. 182-185

Author(s):

Xiao Feng He ◽

Shuai Wang ◽

Tie Jun Ge ◽

Xue Quan Zhang ◽

Chun Yu Zhang

Keyword(s):

High Temperature ◽

Melting Temperature ◽

Crystallization Temperature ◽

Crystallization Behavior ◽

Strong Impact ◽

Crystallization Behaviors ◽

Supercooling Temperature ◽

Melting And Crystallization

The melting and crystallization behaviors of Polypropylene/Syndiotactic1,2-polybutadiene (PP/s-PB) blends and neat PP were studied by using DSC, the results showed that the presence of s-PB in PP would have a strong impact on the crystallization capacity of PP. The presence of s-PB in PP could increase the crystallization temperature(Tc) of PP, and the s-PB could obviously lower supercooling temperature(Tm-Tc) of PP, but the s-PB in PP have a Slightly influence on the melting temperature(Tm) of PP. The proposed reason for those are that the crosslinking s-PB in high temperature is a nucleator for PP’s crystallization and increases PP’s crystalline rate. However, the s-PB lowers PP’s crystallinity. At the same time, the presence of PP in blends lowers s-PB’s crystallinity, but the PP in blends have a Slightly influence on the melting temperature(Tm) and crystallization temperature(Tc) of s-PB.

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Thermodynamics of Crystallization in High Polymers. Natural Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3542833 ◽

1955 ◽

Vol 28 (3) ◽

pp. 718-727 ◽

Cited By ~ 3

Author(s):

Donald E. Roberts ◽

Leo Mandelkern

Keyword(s):

Natural Rubber ◽

Melting Temperature ◽

Low Temperatures ◽

Rapid Heating ◽

Heat Of Fusion ◽

Low Molecular Weight ◽

Heating Rates ◽

Equilibrium Melting Temperature ◽

Clapeyron Equation ◽

Melting Temperatures

Abstract The existence of an equilibrium melting temperature, T0m, at 28 ± 1°, for unstretched natural rubber has been established, using dilatometric methods. The lower melting temperatures previously observed are a consequence of the low temperatures of crystallization and the rapid heating rates employed. From melting point studies of mixtures of the polymer with low molecular-weight diluents, the heat of fusion per repeating unit, ΔHu has been evaluated as 15.3 ± 0.5 cal./g. The values of ΔHu and T0m have then been combined with data of other workers to obtain the following information concerning natural rubber: (1) The variation of melting temperature with applied hydrostatic pressure has been calculated from the Clapeyron equation to be 0.0465° C/atm. (2) The degree of erystallinity resulting from maintaining a sample at 0° until the rate of crystallization is negligible has been calculated, by three independent methods, to be in the range 26 to 31 per cent. (3) Analysis of the stress-strain-temperature relationship has indicated that crystallization is the cause of the large internal energy changes that are observed at relatively high elongations.

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