The crystallization kinetics and morphology of poly(ethylene suberate) (PESub) were studied in detail with differential scanning calorimetry, polarized optical microscopy, and wide-angle X-ray diffraction. The Avrami equation could describe the overall isothermal melt crystallization kinetics of PESub at different crystallization temperatures; moreover, the overall crystallization rate of PESub decreased with increasing crystallization temperature. The equilibrium melting point of PESub was determined to be 70.8°C. Ring-banded spherulites and a crystallization regime II to III transition were found for PESub. The Tobin equation could describe the nonisothermal melt crystallization kinetics of PESub at different cooling rates, while the Ozawa equation failed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43086.

In this work, the nonisothermal and isothermal cold crystallization behaviors of poly(l-lactide) (PLLA)/trisilanolisobutyl-polyhedral oligomeric silsesquioxanes (tsib-POSS) nanocomposites with low tsib-POSS contents were fully investigated. For all the samples, the variations of heating rate and the tsib-POSS loading may influence the nonisothermal cold crystallization of PLLA. During the nonisothermal crystallization kinetics study, the Ozawa equation failed to fit the nonisothermal crystallization process of PLLA, while the Tobin equation could fit it well. For the isothermal crystallization kinetics study, the crystallization rates of all the samples increased with increasing crystallization temperature. The cold crystallization activation energy of PLLA was increased with 1 wt % tsib-POSS. Moreover, the addition of tsib-POSS and the increment of tsib-POSS loading could increase the crystallization rate of PLLA, indicating the nucleating agent effect of tsib-POSS. However, the crystallization mechanism and crystal structure of PLLA remained unchanged in the nanocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43896.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/phenolic blends are new miscible crystalline/amorphous polymer blends prepared via solution casting method in this work, as evidenced by the single composition dependent glass transition temperature. The measured T_gs can be well fitted by the Kwei equation with a q value of 13.6 for the PHBV/phenolic blends, indicating that the interaction between the two components is strong. The negative polymer–polymer interaction parameter, obtained from the melting depression of PHBV using the Nishi-Wang equation, indicating the thermal miscibility of PHBV and phenolic. The spherulitic morphology and crystal structure of PHBV/phenolic blends were studied with polar optical microscopy and wide angle X-ray diffraction compared with those of neat PHBV. It is found that the growth rates of PHBV in the blends are lower than that in neat PHBV at a given crystallization temperature, and the crystal structure of PHBV is not modified by the presence of phenolic in the PHBV/phenolic blends, but the crystallinity decrease with the increasing of phenolic. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Biodegradable poly(butylene succinate-co-butylene adipate) (PBSA)/multiwalled carbon nanotubes (MWCNTs) nanocomposites were prepared via a simple melt-compounding method at low MWCNTs contents. Scanning and transmission electron microscopy observations revealed a relatively nice dispersion of MWCNTs throughout the PBSA matrix. Both the nonisothermal and isothermal melt crystallizations of PBSA were enhanced significantly in the nanocomposites relative to neat PBSA because of the presence of MWCNTs; however, the crystal structure of PBSA remained unchanged. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Miscibility, isothermal melt crystallization kinetics, spherulitic morphology and growth rates, and crystal structure of completely biodegradable poly(ε-caprolactone) (PCL)/tannic acid (TA) blends were studied by differential scanning calorimetry, polarized optical microscopy, and wide angle X-ray diffraction in detail in this work. PCL and TA are miscible as evidenced by the single composition dependent glass transition temperature over the whole compositions range and the depression of equilibrium melting point of PCL in the PCL/TA blends. Isothermal melt crystallization kinetics of neat PCL and an 80/20 PCL/TA blend was investigated and analyzed by the Avrami equation. The overall crystallization rates of PCL decrease with increasing crystallization temperature for both neat PCL and the PCL/TA blend; moreover, the overall crystallization rate of PCL is slower in the PCL/TA blend than in neat PCL at a given crystallization temperature. However, the crystallization mechanism of PCL does not change despite crystallization temperature and the addition of TA. The spherulitic growth rates of PCL also decrease with increasing crystallization temperature for both neat PCL and the PCL/TA blend; moreover, blending with TA reduces the spherulitic growth rate of PCL in the PCL/TA blend. It is also found that the crystal structure of PCL is not modified in the PCL/TA blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Miscibility and crystallization of biodegradable poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx)/poly(vinyl phenol) (PVPh) blends were investigated in this work. PHBHHx is miscible with PVPh over the whole composition range as evidenced by the single composition dependent glass transition temperature and the depression of equilibrium melting point of PHBHHx in the blends. The overall crystallization rates decrease with increasing crystallization temperature for both neat PHBHHx and its blends with PVPh; moreover, the overall crystallization rates are slower in the PHBHHx/PVPh blends than in neat PHBHHx at the same crystallization temperature. Blending with PVPh may change the crystallization mechanism of PHBHHx in the blends compared with that of neat PHBHHx. Both neat PHBHHx and the PHBHHx/PVPh blends exhibit a crystallization regime II to III transition. The crystal structure of PHBHHx is not modified in the PHBHHx/PVPh blends; however, the values of crystal layer thickness, amorphous layer thickness, and long period all become larger with increasing PVPh content in the blends. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

Biodegradable poly(3-hydroxybutyrate) (PHB)/functionalized multi-walled carbon nanotubes (f-MWNTs) nanocomposite was prepared in this work by solution casting method at 2 wt% f-MWNTs loading. Scanning electron microscopy and transmission electron microscopy observations indicate a homogeneous distribution of f-MWNTs in the PHB matrix. Nonisothermal melt crystallization, overall isothermal melt crystallization kinetics, and crystalline morphology of neat PHB and the PHB/f-MWNTs nanocomposite were studied in detail. It is found that the presence of f-MWNTs enhances the crystallization of PHB during nonisothermal and isothermal melt crystallization processes in the nanocomposite due to the heterogeneous nucleation effect of f-MWNTs. Moreover, the incorporation of a small quantity of f-MWNTs apparently improves the thermal stability of the PHB/f-MWNTs nanocomposite with respect to neat PHB. Two methods are employed to study the activation energies of thermal degradation for both the neat PHB and the PHB/f-MWNTs nanocomposite. The activation energy of thermal degradation of the PHB/f-MWNTs nanocomposite is higher than that of neat PHB. Copyright © 2009 John Wiley & Sons, Ltd.

Biodegradable poly(butylene succinate) (PBSU)/carboxyl-functionalized multi-walled carbon nanotubes (f-MWNTs) nanocomposites were prepared via solution casting method at low f-MWNTs loadings of 0.5 and 1 wt%, respectively, in this work. Scanning and transmission electron microscopic observations reveal a fine dispersion of f-MWNTs throughout the PBSU matrix. Non-isothermal melt crystallization at different cooling rates, isothermal melt crystallization at different crystallization temperatures, spherulitic morphology, and crystal structure of neat PBSU and its nanocomposites were investigated with various techniques in detail. The addition of f-MWNTs is found to enhance the crystallization of PBSU, apparently in the nanocomposites during both nonisothermal and isothermal melt crystallization, due to the heterogeneous nucleation effect; however, the crystallization mechanism and crystal structure of PBSU remain almost unchanged. Effect of the presence of f-MWNTs and their loadings on the thermodynamic driving force for nucleation and nucleation activity of PBSU was evaluated quantitatively through two methods. Moreover, it is found that incorporating with 1 wt% f-MWNTs significantly improves the storage modulus of PBSU in the nanocomposites by about 147% at room temperature as compared with that of neat PBSU. Copyright © 2010 John Wiley & Sons, Ltd.

Intercalated and exfoliated nanocomposites of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) and Cloisite 30B (C30B) were fabricated by a solution-casting method to study the effects of the clay loading on the crystallization behavior, thermal stability, and dynamic mechanical properties of PBAT in PBAT/C30B nanocomposites. X-ray diffraction and transmission electron microscopy results indicated the formation of exfoliated nanocomposites at low clay loadings (<5 wt %) and a mixture of exfoliated and intercalated nanocomposites with a clay content of 8 wt % throughout the PBAT matrix. Nonisothermal melt crystallization studies indicated that C30B enhanced the crystallization of PBAT, apparently because of a heterogeneous nucleation effect. Moreover, an attempt was made to quantitatively study the influence of the presence of C30B and its contents on the nucleation activity of PBAT in the PBAT/C30B nanocomposites. The thermal stability of PBAT decreased slightly in the nanocomposites. However, the storage modulus of PBAT apparently increased with the C30B loading increasing in the PBAT/C30B nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Miscibility and crystallization behaviors of biodegradable poly(butylene succinate-co-butylene terephthalate) (PBST)/poly(hydroxyl ether biphenyl A) (phenoxy) blends were investigated with various techniques in this work. PBST and phenoxy are completely miscible as evidenced by the single composition-dependent glass transition temperature over the entire blend compositions. Nonisothermal melt crystallization peak temperature is higher in neat PBST than in the blends at a given cooling rate. Isothermal melt crystallization kinetics of neat and blended PBST was studied and analyzed by the Avrami equation. The overall crystallization rate of PBST decreases with increasing crystallization temperature and the phenoxy content in the PBST/phenoxy blends; however, the crystallization mechanism of PBST does not change. Moreover, blending with phenoxy does not modify the crystal structure but reduces the crystallinity degree of PBST in the PBST/phenoxy blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The crystallization, melting behavior, and spherulitic growth kinetics of biodegradable poly(ethylene succinate-co-6 mol % butylene succinate) [P(ES-co-6 mol % BS)] were investigated and compared with those of the homopolymer poly(ethylene succinate) (PES) in this work. The crystal structure of P(ES-co-6 mol % BS) was the same as that of neat PES, but the crystallinity decreased slightly because of the incorporation of the butylene succinate content. The glass-transition temperature decreased slightly for P(ES-co-6 mol % BS) compared to that for neat PES. The melting point of P(ES-co-6 mol % BS) decreased apparently; moreover, the equilibrium melting point was also reduced. Two melting endotherms were found for P(ES-co-6 mol % BS) after isothermal crystallization; this was ascribed to the melting, recrystallization, and remelting mechanism. The spherulitic growth rate of P(ES-co-6 mol % BS) was slower than that of neat PES at a given crystallization temperature. Both neat PES and P(ES-co-6 mol % BS) exhibited a crystallization regime II to III transition; moreover, the crystallization regime transition temperature of P(ES-co-6 mol % BS) shifted to a low temperature compared with that of neat PES. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Crystallization behavior of biodegradable poly(L-lactide) (PLLA) and its nanocomposites at different carboxyl-functionalized multiwalled carbon nanotubes (f-MWNTs) contents from the amorphous state was studied in detail in this work. For the isothermal cold crystallization, the presence of f-MWNTs enhances the isothermal cold crystallization of PLLA in the nanocomposites compared with that of neat PLLA at the same crystallization temperature; moreover, the overall cold crystallization rate of PLLA increases with increasing the f-MWNTs content in the PLLA matrix while the crystallization mechanism does not change. For the nonisothermal crystallization, the f-MWNTs also accelerate the crystallization process of PLLA. In addition, the activation energies of nonisothermal cold crystallization process were calculated using both the Kissinger and Friedman methods. The cold crystallization activation energies of PLLA are higher in the nanocomposites than in neat PLLA, indicating that the addition of f-MWNTs into the PLLA matrix acts as a physical hindrance to retard crystallization. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Biodegradable poly(ε-caprolactone) (PCL)/polyhedral oligomeric silsesquioxanes (POSS) nanocomposites at various POSS loadings were prepared via solution casting method in this work. Scanning electron microscopy observation indicates that POSS are homogeneously dispersed in the PCL matrix. The experiments show that the crystallization peak temperature is higher in the nanocomposites than in neat PCL during nonisothermal melt crystallization; moreover, the overall crystallization rate is faster in the nanocomposites than in neat PCL during isothermal melt crystallization. Both nonisothermal and isothermal melt crystallization studies suggest that the crystallization of PCL is enhanced by the presence of POSS and influenced by the POSS loading. The effect of POSS on the crystallization is twofold: the presence of POSS may provide heterogeneous nucleation sites for the PCL crystallization while the aggregates of POSS may restrict large crystal growth of PCL. However, the crystallization mechanism and crystal structure of PCL remain almost unchanged despite the presence of POSS in the nanocomposites. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

In this work, nonisothermal melt crystallization and subsequent melting behavior of poly(hydroxybutyrate) (PHB) and its nanocomposites at different multiwalled carbon nanotubes (MWCNTs) loadings were investigated. Increasing the MWCNTs loadings has enhanced the nonisothermal melt crystallization of PHB significantly in the nanocomposites when compared with that of the neat PHB; furthermore, increasing the cooling rates shift the crystallization exotherms to low temperature range for both neat PHB and its nanocomposites. Double melting behavior is found for both neat PHB and its nanocomposites crystallized nonisothermally from the melt, which is explained by the melting, recrystallization, and remelting model. Effects of the MWCNTs loadings, cooling rates, and heating rates on the subsequent melting behavior of PHB were studied in detail. It is found that increasing the MWCNTs loadings, decreasing the cooling rates, and increasing the heating rates would restrict the occurrence of the recrystallization of PHB in the nanocomposites. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2238–2246, 2009