Crystallization behavior of biodegradable poly(L‐lactide)/multiwalled carbon nanotubes nanocomposites from the amorphous state

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     

Crystallization kinetics of poly(L‐lactide)/carbonated hydroxyapatite nanocomposite microspheres

Microspheres consisting of carbonated hydroxyapatite (CHAp) nanoparticles and poly(L ‐lactide) (PLLA) have been fabricated for use in the construction of osetoconductive bone tissue engineering scaffolds by selective laser sintering (SLS). In SLS, PLLA polymer melts and crystallizes. It is therefore necessary to study the crystallization kinetics of PLLA/CHAp nanocomposites. The effects of 10 wt% CHAp nanoparticles on the isothermal and nonisothermal crystallization behavior of PLLA matrix were studied, using neat PLLA for comparisons. The Avrami equation was successfully applied for the analysis of isothermal crystallization kinetics. Using the Lauritzen‐Hoffman theory, the transition temperature from crystallization Regime II to Regime III was found to be around 120°C for both neat PLLA and PLLA/CHAp nanocomposite. The combined Avrami‐Ozawa equation was used to analyze the nonisothermal crystallization process, and it was found that the Ozawa exponent was equal to the Avrami exponent for neat PLLA and PLLA/CHAp nanocomposite, respectively. The effective activation energy as a function of the relative crystallinity and temperature for neat PLLA and PLLA/CHAp nanocomposite under the nonisothermal crystallization condition was obtained by using the Friedman differential isoconversion method. The Lauritzen‐Hoffman parameters were also determined from the nonisothermal crystallization data by using the Vyazovkin‐Sbirrazzuoli equation. CHAp nanoparticles in the composite acted as an efficient nucleating agent, enhancing the nucleation rate but at the same time reducing the spherulite growth rate. This investigation has provided significant insights into the crystallization behavior of PLLA/CHAp nanocomposites, and the results obtained are very useful for making good quality PLLA/CHAp scaffolds through SLS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Crystallization behavior of ultrahigh‐molecular‐weight polyethylene/polyhedral oligomeric silsesquioxane nanocomposites prepared by ethylene in situ polymerization

A [3‐t‐Bu‐2‐O? C₆H₃CH?N(C₆F₅)]₂TiCl₂ catalyst (bis(phenoxyimine)titanium dichloride complex – FI catalyst) was immobilized on disilanolisobutyl polyhedral oligomeric silsesquioxane (OH‐POSS) to prepare ultrahigh molecular‐weight polyethylene (UHMWPE)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites during ethylene in situ polymerization. The dispersion state of POSS in the UHMWPE matrix was characterized by X‐ray diffraction measurements and transmission electron microscopy. It was shown that the OH‐POSS achieved uniformed dispersion in the UHMWPE matrix, although its polarity was unmatched. The isothermal and nonisothermal crystallization behavior of the nanocomposites was investigated by means of differential scanning calorimetry. The crystallization rate of the nanocomposites was enhanced because of the incorporation of POSS during the isothermal crystallization. POSS acted as a nucleus for the initial nucleation and the subsequent growth of the crystallites. For nonisothermal studies, POSS showed an increase in the crystallinity. The crystallization rate of the nanocomposites decreased because the presence of POSS hindered the crystal growth. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40847.     

Crystallization behavior and isothermal crystallization kinetics of PLLA blended with ionic liquid, 1‐butyl‐3‐methylimidazolium dibutylphosphate

The crystallization behavior and isothermal crystallization kinetics of neat poly(l ‐lactic acid) (PLLA) and PLLA blended with ionic liquid (IL), 1‐butyl‐3‐methylimidazolium dibutylphosphate, were researched by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X‐ray diffraction (WXRD). Similar to the non‐isothermal crystallization behavior of neat PLLA, when PLLA melt was cooled from 200 to 20°C at a cooling rate of 10°C min^?1, no crystallization peak was detected yet with the incorporation of IL. However, the glass transition temperature and cold crystallization temperature of PLLA gradually decreased with the increase of IL content. It can be attributed to the significant plasticizing effect of IL, which improved the chain mobility and cold crystallization ability of PLLA. Isothermal crystallization kinetics was also analyzed by DSC and described by Avrami equation. For neat PLLA and IL/PLLA blends, the Avrami exponent n was almost in the range of 2.5–3.0. It is found that t_1/2 reduced largely, and the crystallization rate constant k increased exponentially with the incorporation of IL. These results show that the IL could accelerate the overall crystallization rate of PLLA due to its plasticizing effect. In addition, the dependences of crystallization rate on crystallization temperature and IL content were discussed in detail according to the results obtained by DSC and POM measurements. It was verified by WXRD that the addition of IL could not change the crystal structure of PLLA matrix. All samples isothermally crystallized at 100°C formed the α‐form crystal. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41308.     

Crystallization kinetics of poly (L‐lactic acid)/montmorillonite nanocomposites under isothermal crystallization condition

Poly(L ‐lactic acid)/o‐MMT nanocomposites, incorporating various amounts of organically modified montmorillonite (o‐MMT; 0–10 wt %), were prepared by solution intercalation. The montmorillonite (MMT) was organically modified with dilauryl dimethyl ammonium bromide (DDAB) by ion exchange. Transmission electron microscopy (TEM) and X‐ray diffraction (XRD) reveal that the o‐MMT was exfoliated in a poly(L ‐lactic acid), (PLLA) matrix. A series of the test specimens were prepared and subjected to isothermal crystallization at various temperatures (T₁–T₅). The DSC plots revealed that the PLLA/o‐MMT nanocomposites that were prepared under nonisothermal conditions exhibited an obvious crystallization peak and recrystallization, but neat PLLA exhibited neither. The PLLA/o‐MMT nanocomposites (2–10 wt %) yielded two endothermic peaks only under isothermal conditions at low temperature (T₁), and the intensity of Tm₂ (the higher melting point) was proportional to the o‐MMT content (at around 171°C). The melting point of the test samples increased with the isothermal crystallization temperature. In the Avrami equation, the constant of the crystallization rate (k) was inversely proportional to the isothermal crystallization temperature and increased with the o‐MMT content, especially at low temperature (T₁). The Avrami exponent (n) of the PLLA/o‐MMT nanocomposites (4–10 wt %) was 2.61–3.56 higher than that of neat PLLA, 2.10–2.56, revealing that crystallization occurred in three dimensions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Crystallization behavior and nucleation analysis of poly(l‐lactic acid) with a multiamide nucleating agent

To accelerate the crystallization of poly(L ‐lactic acid) (PLLA) and enhance its crystallization ability, a multiamide nucleator (TMC) was introduced into the PLLA matrix. The thermal characteristics, isothermal and nonisothermal crystallization behavior of pure PLLA and TMC‐nucleated PLLA were investigated by differential scanning calorimetry. The determination of thermal characteristics shows that the addition of TMC can significantly decrease the onset temperature of cold crystallization and meanwhile elevate the total crystallinity of PLLA. For the isothermal crystallization process, it is found that the overall crystallization rate is much faster in TMC‐nucleated PLLA than in pure PLLA and increases as the TMC content is increased, however, the crystal growth form and crystalline structure are not influenced much despite the presence of TMC. In the case of nonisothermal crystallization, the nucleation efficiency and nucleation activity were estimated and the results indicate that excellent nucleation‐promoting effect could be achieved when the weight percentage of TMC is chosen between 0.25% and 0.5%. Polarized optical microscopy observation reveals that the nuclei number of PLLA increases and the spherulite size reduces greatly with the addition of TMC. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Crystallization behavior of biodegradable poly(L‐lactic acid) filled with a powerful nucleating agent: N,N′‐bis(benzoyl) suberic acid dihydrazide

N,N′‐Bis(benzoyl) suberic acid dihydrazide (NA) as nucleating agent for poly(L ‐lactic acid) (PLLA) was synthesized from benzoyl hydrazine and suberoyl chloride, which was deprived from suberic acid via acylation. PLLA/NA samples were prepared by melt blending and a hot‐press forming process. The nonisothermal and isothermal crystallization, spherulite morphology, and melting behavior of PLLA/NA with different contents of NA were investigated with differential scanning calorimetry, depolarized‐light intensity measurement, scanning electron microscopy, polarized optical microscopy, and wide‐angle X‐ray diffraction. With the incorporation of NA, the crystallization peak became sharper and shifted to a higher temperature as the degree of supercooling decreased at a cooling rate of 1°C/min from the melt. Nonisothermal crystallization indicated that the presence of NA accelerated the overall PLLA crystallization. In isothermal crystallization from the melt, the presence of NA affected the isothermal crystalline behaviors of PLLA remarkably. The addition of NA led to a shorter crystallization time and a faster overall crystallization rate; this meant that there was a heterogeneous nucleation effect of NA on the crystallization of PLLA. With the addition of 0.8% NA, the crystallization half‐time of PLLA/NA decreased from 26.5 to 1.4 min at 115°C. The Avrami theory was used to describe the kinetics of isothermal crystallization of the PLLA/NA samples. Also, with the presence of NA, the spherulite number of PLLA increased, and the spherulite size decreased significantly. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Largely improved crystallization behavior and thermal stability of poly(L‐lactide) via the synergistic effects of graphene oxide and carbon nanotubes

Graphene oxide (GO) and carbon nanotubes (CNTs) and their compound were introduced into semicrystalline poly(l ‐lactide) (PLLA) to prepare the corresponding binary and/or ternary nanocomposites, respectively. The dispersion states of nanofillers in different nanocomposites were investigated using UV‐Vis spectroscopy, scanning electron microscopy (SEM) and rheological measurement. The results showed that when GO and CNTs were simultaneously present in the PLLA matrix, good dispersion states of both GO and CNTs could be achieved and the ternary nanocomposites exhibited percolated network structure. The effects of different nanofillers on the crystallization behavior of PLLA matrix were comparatively investigated under the different crystallization conditions including melt crystallization process (nonisothermal and isothermal crystallization from the melt) and cold crystallization (crystallization occurring from an amorphous state during the annealing process). The results showed that GO and CNTs exhibited apparent synergistic effects in improving crystallization ability and enhancing crystallinity of PLLA matrix. Study on the thermal stability of nanocomposites showed that the presence of nanofillers greatly improved the thermal stability of PLLA matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40143.     

Non‐isothermal crystallization kinetics of PEG plasticized PLA/G‐POSS nanocomposites

In this study, the non‐isothermal crystallization kinetics of epoxy functionalized poly(hedral oligomeric silsesquioxane) (G‐POSS) reinforced plasticized or unplasticized poly(lactic acid) (PLA) was investigated. Poly(ethylene glycol) (PEG) was used as plasticizer at a constant content of 10% by weight. A micro‐compounder was used to prepare PLA/G‐POSS, PLA/PEG, and PLA/PEG/G‐POSS nanocomposites. G‐POSS content was varied as 1, 3, 7, and 10 wt%. Avrami, Ozawa, and combined Avrami‐Ozawa kinetic models were implemented to understand the non‐isothermal crystallization behavior of aforementioned nanocomposites. Moreover, the nucleation activity of G‐POSS particles was investigated in terms of Dobreva and Gutzow models. The data for kinetic analysis were obtained through differential scanning calorimeter. It was found that the crystallization rate of both plasticized and unplasticized PLA nanocomposites increased with the addition of G‐POSS. It was highlighted that G‐POSS is an effective nucleating agent for plasticized and unplasticized PLA nanocomposites. In parallel, these findings were in good agreement with activation energies obtained from Friedman model. In addition, all kinetic results were supported by polarized optical microscopy. POLYM. COMPOS., 38:1378–1389, 2017. © 2015 Society of Plastics Engineers     

Cold‐crystallization kinetics of syndiotactic polystyrene

The kinetics of the isothermal and nonisothermal cold crystallization of syndiotactic polystyrene (s‐PS) were characterized with differential scanning calorimetry. A Johnson–Mehl–Avrami analysis of the isothermal experiments indicated that the cold crystallization of s‐PS at a constant temperature followed a diffusion‐controlled growth mode with a decreasing nucleation rate. Furthermore, the slow nucleation rate was the controlling step of the entire kinetic process. For nonisothermal cold‐crystallization kinetics, we used a simple model based on a combination of the well‐known Avrami and Ozawa models. The analysis revealed that, unlike for melt crystallization, the Avrami and Ozawa exponents were not equal. The activation energies for the isothermal and nonisothermal cold crystallizations of s‐PS were 792.0 and 148.62 kJ mol^?1, respectively, indicating that the smaller motion units in cold crystallization had a weaker temperature dependence than those in melt crystallization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3464–3470, 2003     

Effect of zinc phenylphosphonate on the crystallization behavior of poly(l‐lactide)

The effect of zinc phenylphosphonate (PPZn) on the crystallization behavior of poly(l ‐lactide) (PLLA) was investigated using differential scanning calorimetry (DSC) and Polarized Optical Microscopy (POM) measurements. The non‐isothermal cold crystallization results showed that the addition of PPZn obviously decreased the cold crystallization temperature of PLLA and increased the degree of crystallinity of PLLA. The isothermal crystallization kinetics results showed that the crystallization rate of PLLA with small amount of PPZn was much higher than that of neat PLLA, and the half‐time (t_1/2) of PLLA/PPZn sample is far less than that of neat PLLA. As an effective nucleating agent, PPZn particles had also some influence on nucleation mechanism and crystal growth of PLLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2744–2752, 2013     

Crystallization and thermal behavior of microcellular injection‐molded polyamide‐6 nanocomposites

This article presents the effects of nanoclay and supercritical nitrogen on the crystallization and thermal behavior of microcellular injection‐molded polyamide‐6 (PA6) nanocomposites with 5 and 7.5 wt% nanoclay. Differential scanning calorimetry (DSC), X‐ray diffractometry (XRD), and polarized optical microscopy (POM) were used to characterize the thermal behavior and crystalline structure. The isothermal and nonisothermal crystallization kinetics of neat resin and its corresponding nanocomposite samples were analyzed using the Avrami and Ozawa equations, respectively. The activation energies determined using the Arrhenius equation for isothermal crystallization and the Kissinger equation for nonisothermal crystallization were comparable. The specimen thickness had a significant influence on the nonisothermal crystallization especially at high scanning rates. Nanocomposites with an optimal amount of nanoclay possessed the highest crystallization rate and a higher level of nucleation activity. The nanoclay increased the magnitude of the activation energy but decreased the overall crystallinity. The dissolved SCF did not alter the crystalline structure significantly. In contrast with conventionally injection‐molded solid counterparts, microcellular neat resin parts and microcellular nanocomposite parts were found to have lower crystallinity in the core and higher crystallinity near the skin. POLYM. ENG. SCI., 46:904–918, 2006. © 2006 Society of Plastics Engineers     

Synergistic effect of poly(ethylene glycol) and graphene oxides on the crystallization behavior of poly(l‐lactide)

In this article, we report the combined effects of poly(ethylene glycol) (PEG) and/or graphene oxides (GOs) on the crystallization behavior of poly(l ‐lactide) (PLLA) under different crystallization conditions, such as nonisothermal crystallization, isothermal crystallization, and annealing‐induced cold crystallization. Differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction, and polarized optical microscopy were used to study the crystallization kinetics and crystallinity to illustrate the effects of PEG and/or GOs on the crystallization behavior of PLLA. The results show that PEG functioned as a plasticizer and improved the chain mobility of /PLLA during crystallization and the GOs acted as efficient nucleation agents and accelerated the crystallization rate. Finally, both PEG and GOs improved the crystallization ability of PLLA. Importantly, the simultaneous addition of PEG and GOs led to a synergistic effect on the crystallization behavior of PLLA under all conditions. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3498–3508, 2013     

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

The isothermal crystallization behavior of poly(L ‐lactic acid)/organo‐montmorillonite nanocomposites (PLLA/OMMT) with different content of OMMT, using a kind of twice‐functionalized organoclay (TFC), prepared by melt intercalation process has been investigated by optical depolarizer. In isothermal crystallization from melt, the induction periods (t_i) and half times for overall PLLA crystallization (100°C ≤ T_c ≤ 120°C) were affected by the temperature and the content of TFC in nanocomposites. The kinetic of isothermal crystallization of PLLA/TFC nanocomposites was studied by Avrami theory. Also, polarized optical photomicrographs supplied a direct way to know the role of TFC in PLLA isothermal crystallization process. Wide angle X‐ray diffraction (WAXD) patterns showed the nanostructure of PLLA/TFC material, and the PLLA crystalline integrality was changed as the presence of TFC. Adding TFC led to the decrease of equilibrium melting point of nanocomposites, indicating that the layered structure of clay restricted the full formation of crystalline structure of polymer. The specific interaction between PLLA and TFC was characterized by the Flory‐Huggins interaction parameter (B), which was determined by the equilibrium melting point depression of nanocomposites. The final values of B showed that PLLA was more compatible with TFC than normal OMMT. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Isothermal crystallization of HDPE/octamethyl polyhedral oligomeric silsesquioxane nanocomposites: Role of POSS as a nanofiller

The isothermal crystallization of HDPE/POSS (polyhedral oligomeric silsesquioxane) nanocomposites (POSS content varying from 0.25 to 10 wt %) was studied using differential scanning calorimetry (DSC) technique. The Avrami model could successfully describe the isothermal crystallization behavior of the nanocomposites. The value of Avrami exponent (n) varies between 2 and 2.5 for all the compositions studied. For a given composition, the values vary with crystallization temperature and in general increased with POSS content up to 1 wt % POSS content and decreased thereafter. The presence of POSS was found to increase the rate of crystallization, which manifested itself in the increased value of the Avrami rate constant (K) and reduced value of crystallization half‐time (t_1/2). The rate of crystallization peaked at 1 wt % POSS content and was almost constant at higher POSS loadings. X‐ray diffraction studies revealed that POSS exists as nanocrystals in HDPE matrix while some POSS gets dispersed at molecular level too. It is observed that only the POSS dispersed at molecular level acts as a nucleating agent while the POSS nanocrystals do not affect the crystallization process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Cold‐crystallization behavior of poly(L‐lactide)/ACR blend films investigated by in situ FTIR spectroscopy

The cold crystallization behavior of poly (L ‐lactide) (PLLA) blend films modified by small amount of acrylic rubber particles (ACR) have been investigated by in situ Fourier‐transform infrared (FTIR) spectroscopy. During the isothermal cold crystallization, the crystallization rate of PLLA is greatly improved with addition of only 1 wt % ACR. However, for PLLA with 8 wt % ACR, the crystallization rate is slower than that of neat PLLA. The relative crystallinity of PLLA with the addition of 1–5 wt % ACR is obviously higher than that of the neat PLLA. For the PLLA blend film with 3 % ACR, the relative crystallinity reaches a maximum. It was found that the addition of ACR particles below 5% accelerated the cold crystallization nucleation process and made the cold‐crystallization rate of PLLA/ACR be quicker than that of neat PLLA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Isothermal and nonisothermal crystallization kinetics of fully bio‐based polyamides

We studied the crystallization behaviors of bio‐based BDIS polyamides synthesized from the following biomass monomers: 1,4‐butanediamine (BD), 1,10‐decanediamine (DD), itaconic acid (IA), and sebacic acid (SA). Isothermal crystallization, melting behavior, and nonisothermal crystallization of BDIS polyamides were investigated by differential scanning calorimetry (DSC). The Avrami equation was used to describe the isothermal crystallization of BDIS polyamides. The modified Avrami equation, the Ozawa equation, the modified Ozawa equation, and an equation combining the Avrami and Ozawa equations were used to describe the nonisothermal crystallization. The equilibrium melting point temperature of BDIS polyamide was determined to be 163.0°C. The Avrami exponent n was found to be in the range of 2.21–2.79 for isothermal crystallization and 4.10–5.52 for nonisothermal crystallization. POLYM. ENG. SCI., 56:829–836, 2016. © 2016 Society of Plastics Engineers     

Isothermal crystallization kinetics and melting behavior of modified high‐density polyethylene/barium sulfate nanocomposites

The melting/crystallization behavior and isothermal crystallization kinetics of high‐density polyethylene (HDPE)/barium sulfate (BaSO₄) nanocomposites were studied with differential scanning calorimetry (DSC). The isothermal crystallization kinetics of the neat HDPE and nanocomposites was described with the Avrami equation. For neat HDPE and HDPE/BaSO₄ nanocomposites, the values of n ranges from 1.7 to 2.0. Values of the Avrami exponent indicated that crystallization nucleation of the nanocomposites is two‐dimensional diffusion‐controlled crystal growth. The multiple melting behaviors were found on DSC scan after isothermal crystallization process. The multiple endotherms could be attributed to melting of the recrystallized materials or the secondary lamellae caused during different crystallization processes. Adding the BaSO₄ nanoparticles increased the equilibrium melting temperature of HDPE in the nanocomposites. Surface free energy of HDPE chain folding for crystallization of HDPE/BaSO₄ nanocomposites was lower than that of neat HDPE, confirming the heterogeneous nucleation effect of BaSO₄. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Thermal transitions and stability of melt mixed TiO2/Poly(L‐lactic acid) nanocomposites

Poly(L‐lactic acid) (PLLA) nanocomposites containing 5, 10, and 20 wt% titanium dioxide (TiO₂), were prepared by mixing in a co‐rotating twin‐screw extruder. By X‐ray diffraction, a transformation of less ordered (α’‐form) to better organized crystalline (α‐form) structure of PLLA was observed with increasing TiO₂ content. Differential scanning calorimetry (DSC) tests revealed that cold crystallization was facilitated, as shown by the decrease of cold crystallization temperature (T_cc). The main melting peak of PLLA phase in nanocomposites, shifted towards higher temperatures and a shoulder appeared in the lower temperature flank of the curve, revealing a second peak for 20/80 w/w TiO₂/PLLA nanocomposites. The effect of TiO₂ on the isothermal crystallization of PLLA, in the temperature range T_ic: 100–120°C, was also investigated by DSC. At lower temperatures (T_ic: 100 and 110°C), the effect of TiO₂ nanoparticles is an increase of the crystallization rate, leading to lower time for the completion of crystallization, in comparison with that of pure PLLA. The inverse effect was observed at higher crystallization temperatures (T_ic: 115 and 120°C). The kinetic analysis of the crystallization behavior of the examined nanocomposites fits the Avrami equation quite well and gives values for exponent (n) varying between 2 and 3, suggesting a spherulitic crystalline morphology. POLYM. ENG. SCI., 59:704–713, 2019. © 2018 Society of Plastics Engineers     

Crystallization kinetics,melting behavior,and morphologies of poly(butylene succinate) and poly(butylene succinate)‐block‐poly(propylene glycol) segmented copolyester

This article investigated the crystallization kinetics, melting behavior, and morphologies of poly(butylene succinate)(PBS) and its segmented copolyester poly(butylene succinate)‐block‐poly(propylene glycol)(PBSP) by means of differential scanning calorimetry, polarized light microscopy, and wide angle X‐ray diffraction. Avrami equation was used to describe the isothermal crystallization kinetics. For nonisothermal crystallization studies, the Avrami equation modified by Jeziorny, and the model combining Avrami equation and Ozawa equation were employed. The results showed that the introduction of poly(propylene glycol) soft segment led to suppression of crystallization of PBS hard segment. The melting behavior of the isothermally and nonisothermally crystallized samples was also studied. Results showed that the isothermally crystallized samples exhibited two melting endotherms, whereas only one melting endotherm was shown after nonisothermal crystallization. The spherulitic morphology of PBSP and wide angle X‐ray diffraction showed that the polyether segments were excluded from the crystals and resided in between crystalline PBS lamellae and mixed with amorphous PBS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010