Biodegradable poly(vinyl alcohol)‐graft‐ poly(ε‐caprolactone) comb‐like polyester: Microwave synthesis and its characterization

Poly(vinyl alcohol)‐initiated microwave‐assisted ring opening polymerization of ε‐caprolactone in bulk was investigated, and a series of poly(vinyl alcohol)‐graft‐poly(ε‐caprolactone) (PVA‐g‐PCL) copolymers were prepared, with the degree of polymerization (DP) of PCL side chains and the degree of substitution (DS) of PVA by PCL being in the range of 3–24 and 0.35–0.89, respectively. The resultant comb‐like PVA‐g‐PCL copolymers were confirmed by means of FTIR, ¹H NMR, and viscometry measurement. The introduction of hydrophilic backbone resulted in the decrease in both melting point and crystallization property of the PVA‐g‐PCL copolymers comparing with linear PCL. With higher microwave power, the DP of PCL side chains and DS of PVA backbone were higher, and the polymerization reaction proceeded more rapidly. Both the DP and monomer conversion increased with irradiation time, while the DS increased first and then remained constant. With initiator in low concentration, the DP and DS were higher, while the monomer was converted more slowly. Microwaves dramatically improved the polymerization reaction in comparison of conventional heating method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 3973–3979, 2007     

Kenaf fiber/poly(ε‐caprolactone) biocomposite with enhanced crystallization rate and mechanical properties

Plant‐derived kenaf fiber (KF)‐reinforced poly(ε‐caprolactone) (PCL) biocomposites were successfully fabricated by the melt mixing technique. The crystallization behavior, morphology, and mechanical and dynamic mechanical properties of PCL/KF composites with various KF weight contents were investigated. The crystallization rate, tensile and storage moduli significantly improved as compared to the virgin polymer. The half times of PCL/KF composite (20 wt % fiber content) in isothermal crystallization at 40°C and 45°C reduced to 31.6% and 42.0% of the neat PCL, respectively. Moreover, the tensile and storage modulus of the composite are improved by 146% and 223%, respectively, by the reinforcement with 30% KF. The morphology evaluated by SEM indicates good dispersion and adhesion between KF and PCL. Overall, these findings reveal that KF can be a potential reinforcement for the biodegradable polymer composites owing to its good ability to improve the mechanical properties as well as crystallization rate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of poly(ϵ‐caprolactone)‐b‐poly(ethylene glycol) block copolymers prepared by a salicylaldimine‐aluminum complex

A series of poly(?‐caprolactone)‐b‐poly(ethylene glycol) (PCL‐b‐PEG) block copolymers with different molecular weights were synthesized with a salicylaldimine‐aluminum complex in the presence of monomethoxy poly(ethylene glycol). The block copolymers were characterized by ¹H NMR, GPC, WAXD, and DSC. The ¹H NMR and GPC results verify the block structure and narrow molecular weight distribution of the block copolymers. WAXD and DSC results show that crystallization behavior of the block copolymers varies with the composition. When the PCL block is extremely short, only the PEG block is crystallizable. With further increase in the length of the PCL block, both blocks can crystallize. The PCL crystallizes prior to the PEG block and has a stronger suppression effect on crystallization of the PEG block, while the PEG block only exerts a relatively weak adverse effect on crystallization of the PCL block. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Micro structural and non‐isothermal crystallization and degradation kinetics studies on manganese thioglycolate end capped poly(ε‐caprolactone)

The Manganese thioglycolate (Mn‐TG) end capped poly(ε‐caprolactone) (PCL) was prepared by ring opening polymerization at 160°C under inert atmosphere in the presence of Mn‐TG as an initiator and stannous octoate as a catalyst by bulk polymerization technique. The prepared PCL was investigated using various analytical tools to assess its physico‐chemical properties. The chemical structure of PCL was confirmed by Fourier transform infrared and nuclear magnetic resonance spectroscopic techniques. The particle size and morphology of the sample was examined by atomic force microscopy and TEM. The melting and crystallization behavior of PCL was analyzed using differential scanning calorimetry. The thermal property of PCL was assessed with the help of thermogravimetric analysis (TGA). The non‐isothermal crystallization kinetics was carried out to understand the nucleation type and crystal growth for the prepared PCL. The energy of activation (E_a) for crystallization process of PCL was determined. The thermal degradation of PCL and its E_a was determined under non‐isothermal condition using important kinetic models. POLYM. ENG. SCI., 59:633–642, 2019. © 2018 Society of Plastics Engineers     

Crystallization,mechanical properties,and enzymatic degradation of biodegradable poly(ε‐caprolactone) composites with poly(lactic acid) fibers

Biodegradable polymer composites based on poly(ɛ‐caprolactone) (PCL) and poly(lactic acid) (PLA) fibers were prepared by melt compounding. The effects of PLA fibers on the crystallization, mechanical properties, and enzymatic degradation of PCL composites were investigated. The addition of PLA fibers enhanced the crystallization of PCL due to the heterogeneous nucleation effect of fibers. However, the final crystallinity of the PCL in the composites was little changed in the presence of PLA fibers. With the addition of PLA fibers, significant improvement in storage modulus (E′) of PCL in the composites was achieved. A significant increase in E′ was 173% for the composites as compared to that of the neat PCL at 20°C. With the increase in PLA fibers content, the PCL composites showed decreased elongation and strength at break; however, the tensile yield strength and modulus were increased significantly, indicating that PCL was obviously reinforced by adding PLA fibers. Although the PLA fibers retarded the enzymatic degradation of PCL, it was possible to be completely degraded without much degradation time for PCL blending with suitable amounts of PLA fibers. POLYM. COMPOS., 34:1745–1752, 2013. © 2013 Society of Plastics Engineers     

Preparation and characterization of biodegradable poly(ϵ‐caprolactone) self‐reinforced composites and their crystallization behavior

Self‐reinforced poly(?‐caprolactone) (PCL) composites were prepared by dispersing a homologous nucleating agent within the PCL matrix through melt mixing. Coalesced PCL, featuring more orderly chain arrangements, acted as the nucleating agent leading to improvement of crystallization for the melt PCL matrix. Non‐isothermal melt crystallization behavior, isothermal melt crystallization kinetics, spherulitic morphology and the crystal structure of neat PCL and the PCL self‐reinforced composites were studied in detail. The results indicated that both non‐isothermal and isothermal melt crystallization of PCL composites were enhanced significantly by the homologous nucleating agent, while the crystallization mechanism and crystal structures remained unchanged. The results of tensile mechanical tests showed that the Young's modulus of the composites was improved by up to 77% with the incorporation of 20 wt% nucleating agent. Biocompatibility tests demonstrated that the cells could adhere to and proliferate well on the surface of the self‐reinforced PCL composites. © 2017 Society of Chemical Industry     

Paper‐sheet biocomposites based on wood pulp grafted with poly(ε‐caprolactone)

Kraft pulp fibers were used as substrates for the grafting of poly(ε‐caprolactone) (PCL) from available hydroxyl groups through ring‐opening polymerization, targeting three different chain lengths (degree of polymerization): 120, 240, and 480. In a paper‐making process, paper‐sheet biocomposites composed of grafted fibers and neat pulp fibers were prepared. The paper sheets possessed both the appearance and the tactility of ordinary paper sheets. Additionally, the sheets were homogenous, suggesting that PCL‐grafted fibers and neat fibers were compatible, as demonstrated by both Fourier transform infrared spectroscopy microscopy and through dye‐labeling of the PCL‐grafted fibers. Finally, it was shown that the paper‐sheet biocomposites could be hot‐pressed into laminate structures without the addition of any matrix polymer; the adhesive joint produced could even be stronger than the papers themselves. This apparent and sufficient adhesion between the layers was thought to be due to chain entanglements and/or co‐crystallization of adjacent grafted PCL chains within the different paper sheets. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42039.     

The effect of pH on the hydrolytic degradation of poly(ε‐caprolactone)‐block‐poly(ethylene glycol) copolymers

The in‐vitro hydrolytic behavior of diblock copolymer films consisting of poly(ε‐caprolactone) (PCL) and poly(ethylene glycol) (PEG) was studied at pH 7.4 and pH 9.5 at 37°C. The degradation of these films was characterized at various time intervals by mass loss measurements, GPC, ¹H‐NMR, DSC, FTIR, XRD, and SEM. A faster rate of degradation took place at pH 9.5 than at pH 7.4. Analysis of the molecular weight profile during the course of degradation revealed that random chain scission of the ester bonds in PCL predominates at the initial induction phase of polymer degradation. There was also an insignificant mass loss of the films observed. Mass spectroscopy was used to determine the nature of the water soluble products of degradation. At pH 7.4, a variety of oligomers with different numbers of repeating units were present whereas the harsher degradation conditions at pH 9.5 resulted in the formation of dimers. From the results, it can be proposed that a more complete understanding of the degradation behavior of the PCL‐b‐PEG copolymer can be monitored using a combination of physiological and accelerated hydrolytic degradation conditions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of poly(ε‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ε‐caprolactone) triblock copolymers with dibutylmagnesium as catalyst

Two series of poly(ε‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ε‐caprolactone) triblock copolymers were prepared by the ring opening polymerization of ε‐caprolactone in the presence of poly(ethylene glycol) and dibutylmagnesium in 1,4‐dioxane solution at 70°C. The triblock structure and molecular weight of the copolymers were analyzed and confirmed by ¹H NMR, ¹³C NMR, FTIR, and gel permeation chromatography. The crystallization and thermal properties of the copolymers were investigated by wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). The results illustrated that the crystallization and melting behaviors of the copolymers were depended on the copolymer composition and the relative length of each block in copolymers. Crystallization exothermal peaks (T_c) and melting endothermic peaks (T_m) of PEG block were significantly influenced by the relative length of PCL blocks, due to the hindrance of the lateral PCL blocks. With increasing of the length of PCL blocks, the diffraction and the melting peak of PEG block disappeared gradually in the WAXD patterns and DSC curves, respectively. In contrast, the crystallization of PCL blocks was not suppressed by the middle PEG block. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Miscibility and crystallization behavior of biodegradable poly(ε‐caprolactone)/tannic acid blends

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     

Thermal properties and crystallization behaviour of blends of poly(ε‐caprolactone) with chitin and chitosan

Blend films of poly(ε‐caprolactone) (PCL) with chitin and chitosan were prepared as completely biodegradable polyester/polysaccharide composites. Differential scanning calorimetry and Fourier‐transform infrared (FTIR) spectroscopy revealed that the crystallization of PCL, which had been suppressed by blending with chitin and chitosan, progressed with the elapse of time after film preparation. The suppression of crystallization of PCL by blending with polysaccharides was also observed by solid‐state ¹³C NMR spectroscopy. Furthermore, FTIR spectra indicated that the extent of hydrogen bonding between PCL and polysaccharides, which suppressed the crystallization of PCL, decreased with elapse of time after film preparation. Wide‐angle X‐ray diffraction indicated that the polysaccharides affected the crystallization of PCL and slightly deformed its crystalline lattice. Copyright © 2003 Society of Chemical Industry     

Synthesis,characterization and thermal degradation of poly[2‐(3‐p‐bromophenyl‐3‐methylcyclobutyl)‐2‐hydroxyethylmethacrylate]

In this work, 2‐(3‐p‐bromophenyl‐3‐methylcyclobutyl)‐2‐hydroxyethylmethacrylate (BPHEMA) [monomer] was synthesized by the addition of methacrylic acid to 1‐epoxyethyl‐3‐bromophenyl‐3‐methyl cyclobutane. The monomer and poly(BPHEMA) were characterized by FT‐IR and [¹H] and [¹³C]NMR. Average molecular weight, glass transition temperature, solubility parameter, and density of the polymer were also determined. Thermal degradation of poly[BPHEMA] was studied by thermogravimetry (TG), FT‐IR. Programmed heating was carried out at 10 °C min⁻¹ from room temperature to 500 °C. The partially degraded polymer was examined by FT‐IR spectroscopy. The degradation products were identified by using FT‐IR, [¹H] and [¹³C]NMR and GC‐MS techniques. Depolymerization is the main reaction in thermal degradation of the polymer up to about 300 °C. Percentage of the monomer in CRF (Cold Ring Fraction) was estimated at 33% in the peak area of the GC curve. Intramolecular cyclization and cyclic anhydride type structures were observed at temperatures above 300 °C. The liquid products of the degradation, formation of anhydride ring structures and mechanism of degradation are discussed. © 1999 Society of Chemical Industry     

Fabrication and Physical Properties of Poly(ε‐Caprolactone)/Modified Graphene Nanocomposite

A chemical strategy is attempted to modify graphene for its facilitated dispersion in poly(ε‐caprolactone) (PCL) matrix. Herein, graphite oxide is subjected to sequential treatment with phenyl isocyanate and vitamin C (VC) to yield graphene nanosheets (iG‐VC). It is noteworthy that following the reduction treatment, iG‐VC graphene sheets exfoliate within the PCL matrix and show appreciable interfacial compatibility with PCL matrix in organic solvent by virtue of improved polarity from isocyanate treatment. The tensile yield strength and Young's modulus of the PCL/iG‐VC composite exhibit pronounced enhancement as compared to neat PCL, despite of mere composition of graphene sheets. The tensile yield stress of composite is increased notably to reach 18.6 MPa at 3 wt% graphene sheets as compared to neat PCL. Likewise, Young's modulus of composite is observed to increase from 370 to 470 MPa at 5 wt% graphene sheets. Moreover, the crystallization temperature (T _c) and crystallinity of PCL increase significantly upon incorporation of small amount of iG‐VC. Ultimately, functional role of iG‐VC graphene sheets is demonstrated in enhancing electrical conductivity of PCL‐based nanocomposites. The plausible mechanisms are also proposed to explain the increased T _c, improved mechanical property, and improved electrical conductivity of PCL/iG‐VC composite.

     

Poly(ɛ‐caprolactone)/polyhedral oligomeric silsesquioxane hybrids: Crystallization behavior and thermal degradation

Biodegradable organic–inorganic hybrids based on poly(?‐caprolactone) (PCL) and polyhedral oligomeric silsesquioxane (POSS) with 5.3–21.3 wt % POSS were synthesized via ring‐opening polymerization (ROP). Chemical structures of the polymers were characterized by proton nuclear magnetic resonance (¹H NMR), fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). X‐ray diffraction (XRD) analysis illustrated that both POSS and PCL segment in POSS/PCL hybrids could crystallize and form two well‐separated crystalline phases except in the one with low content of POSS (5.3 wt %). Melting behavior and non‐isothermal crystallization kinetics of POSS/PCL hybrids were studied by differential scanning calorimeter (DSC). The results indicated that the POSS segment suppressed crystallization of the PCL segment to some extent. Polarizing optical microscope (POM) images showed that POSS/PCL hybrids with the highest POSS loading (21.3 wt %) possessed “snowflake” shape crystals whereas the ones with relatively low POSS loading exhibited classic spherulites. Thermogravimetry (TG) measurement revealed that thermal degradation of POSS/PCL hybrids proceeded by four‐step while PCL homopolymers degraded by a single step. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44113.     

Low percolation threshold and high electrical conductivity in melt‐blended polycarbonate/multiwall carbon nanotube nanocomposites in the presence of poly(ε‐caprolactone)

This study focuses on the electrical properties of polycarbonate (PC)/poly(ε‐caprolactone) (PCL)‐multiwall carbon nanotube (MWCNT) nanocomposites. MWCNTs were incorporated into thermoplastic PC matrix by simple melt blending using biodegradable PCL based concentrates with MWCNT loadings (3.5 wt%). Because of the lower interfacial energy between MWCNT and PCL, the nanotubes remain in their excellent dispersion state into matrix polymer. Thus, electrical percolation in PC/PCL‐MWCNT nanocomposites was obtained at lower MWCNT loading rather than direct incorporation of MWCNT into PC matrix. AC and DC electrical conductivity of miscible PC/PCL‐MWCNT nanocomposites were studied in a broad frequency range, 10¹?10⁶ Hz and resulted in low percolation threshold (p_c) of 0.14 wt%, and the critical exponent (t) of 2.09 from the scaling law equation. The plot of logσ_DC versus p^?1/3 showed linear variation and indicated the existence of tunneling conduction among MWCNTs. At low MWCNT loading, the influence of large polymeric gaps between conducting clusters is the reason for the frequency dependent electrical conductivity. Transmission electron microscopy and field emission scanning electron microscopy showed that MWCNTs were homogeneously dispersed and developed a continuous interconnected network path throughout the matrix phase and miscibility behavior of the polymer blend. POLYM. ENG. SCI., 54:646–659, 2014. © 2013 Society of Plastics Engineers     

Crystallization,melting behavior,and wettability of poly(ε‐caprolactone) and poly(ε‐caprolactone)/ poly(N‐vinylpyrrolidone) blends

Both wettability and crystallizability control poly(ε‐caprolactone)'s (PCL) further applications as biomaterial. The wettability is an important property that is governed by both chemical composition and surface structure. In this study, we prepared the PCL/poly(N‐vinylpyrrolidone) (PVP) blends via successive in situ polymerization steps aiming for improving the wettability and decreasing crystallizability of PCL. The isothermal crystallization of PCL/PVP at different PVP concentrations was carried out. The equilibrium melting point (T), crystallization rate, and the melting behavior after isothermal crystallization were investigated using differential scanning calorimetry (DSC). The Avrami equation was used to fit the isothermal crystallization. The DSC results showed that PVP had restraining effect on the crystallizability of PCL, and the crystallization rate of PCL decreased clearly with the increase of PVP content in the blends. The X‐ray diffraction analysis (WAXD) results agreed with that. Water absorptivity and contact angle tests showed that the hydrophilic properties were improved with the increasing content of PVP in blends. The coefficient for the water diffusion into PCL/PVP blends showed to be non‐Fickian in character. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polymorphism and crystallization in poly(vinylidene fluoride)/ poly(ϵ‐caprolactone)–block–poly(dimethylsiloxane)–block–poly(ϵ‐caprolactone) blends

The miscibility, crystallization kinetics and crystalline morphology of a new system of poly(vinylidene fluoride)/poly(?‐caprolactone)‐block‐poly(dimethylsiloxane)‐block‐poly(?‐caprolactone) (PVDF/PCL‐b‐PDMS‐b‐PCL) triblock copolymer were investigated by a variety of techniques. The miscibility and phase behaviour of PVDF/PCL‐b‐PDMS‐b‐PCL were studied by determination of the melting point temperature, crystallization kinetics and Fourier transform infrared (FTIR) mapping. Chemical imaging was used as a new technique to characterize the interaction of polymer blends in crystalline morphology. The results demonstrate the existence of characteristic peaks of both PVDF and PCL in the chosen crystalline area. The crystalline structures of PVDF were affected by the PCL‐b‐PDMS‐b‐PCL triblock copolymer and facilitate the formation of the β polymorph which was illustrated by FTIR analysis. The β crystal phase fraction increases significantly on increasing the composition of the PCL‐b‐PDMS‐b‐PCL triblock copolymer. In addition, confined crystallization of PCL within PVDF inter‐lamellar and/or inter‐fibrillar regions was confirmed through polarizing optical microscopy, wide‐angle X‐ray diffraction and small‐angle X‐ray scattering analysis. © 2019 Society of Chemical Industry     

Synthesis and characterization of polyrotaxanes comprising α‐cyclodextrins and poly(ε‐caprolactone) end‐capped with poly(butyl methacrylate)s

Biodegradable polyrotaxane‐based triblock copolymers were synthesized via the bulk atom transfer radical polymerization (ATRP) of n‐butyl methacrylate (BMA) initiated with polypseudo‐rotaxanes (PPRs) built from a distal 2‐bromoisobutyryl end‐capped poly(ε‐caprolactone) (Br‐PCL‐Br) with α‐cyclodextrins (α‐CDs) in the presence of Cu(I)Br/N,N,N′,N″,N″‐pentamethyldiethylenetriamine at 45 ºC. The structure was characterized in detail by means of ¹H NMR, gel permeation chromatography, wide‐angle X‐ray diffraction, DSC and TGA. When the feed molar ratio of BMA to Br‐PCL‐Br was changed from 128 to 300, the degree of polymerization of PBMA blocks attached to two ends of the PPRs was in the range 382 ? 803. Although about a tenth of the added α‐CDs were still threaded onto the PCL chain after the ATRP process, the movable α‐CDs made a marked contribution to the mechanical strength enhancement, blood anticoagulation activity and protein adsorption repellency of the resulting copolymers. Meanwhile, they could also protect the copolymers from the attack of H₂O and Lipase AK Amano molecules, exhibiting a lower mass loss as evidenced in hydrolytic and enzymatic degradation experiments. © 2013 Society of Chemical Industry     

Structural evolution of uniaxial tensile‐deformed injection molded poly(ɛ‐caprolactone)/hydroxyapatite composites

It is essential to examine the mechanisms of plastic deformation of polymer composites under external loads and large strains, especially if the material is intended to be used in a dynamic environment. This work investigated the variation of structure as well as the properties of poly(ɛ‐caprolactone) (PCL) deformed under different tensile draw ratios and strain rates. The PCL/HA composites were prepared by melt mixing the PCL with up to 10 wt% HA in a twin‐screw extruder. The deformation behavior of the PCL/HA composites revealed a strong correlation between the mechanical response and the accompanying structural transformations. It was found that the strain rate and stretching ratio played important roles in modulating the molecular orientation and crystallization of the PCL/HA composites. The increase in strain rate from 0.2 to 100 mm/min led to the variation of crystallinity from 56.81% to 67.50%. With an increase of the strain rate, the chain extension rate along the stretching direction increased faster than the chain relaxation, which improved the orientation of the polymer chains. The crystallinity and orientation of the deformed PCL/HA composites increased with an increase in draw ratio. The composites also possessed enhanced yield strength resulting from an increased strain rate. POLYM. COMPOS., 38:1771–1782, 2017. © 2015 Society of Plastics Engineers     

Epoxy/poly(ɛ‐caprolactone) nanocomposites: Effect of transformations of structure on crystallization

The influence of morphology of the epoxy/poly(?‐caprolactone) (PCL) system and corresponding nanocomposites with organophilized layered silicate on PCL crystallization was studied by differential scanning calorimetry, scanning, and transmission electron microscopy. The results obtained indicate a significant affecting of nonisothermal PCL crystallization by phase morphology brought about by the reaction‐induced phase separation (RIPS) influenced either by various nanoclay contents or the epoxy/PCL ratio. Dispersed morphology of PCL matrix with epoxy globules induces crystallization at higher temperatures. The inverse dispersed morphology of epoxy matrix with PCL inclusions causes crystallization at lower temperature. The co‐continuous morphology induces crystallization in both steps. Rate of the second crystallization step is substantially higher than that in the first step. No nucleation effect has been found in the nanocomposites with the added nanofiller. Multicomponent samples show retarded crystallization, i.e., lower crystallinities and lower overall crystallization rate compared with neat PCL. The results obtained suggest that it is primarily morphological/interfacial effects that play a decisive role in the crystallization behavior of PCL in the epoxy/PCL/clay system. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3197–3204, 2013