Transesterification in homogeneous poly(?-caprolactone)-epoxy blends

Chen, Jyh-Luen; Hu, Haitao; Li, Ming-Shiu; Chang, Feng‐Chih

doi:10.1002/(sici)1097-4628(19990103)71:1<75::aid-app10>3.0.co;2-2

Cited by 21 publications

(18 citation statements)

References 27 publications

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“…[9][10][11] Although grafting reactions are not discussed in those studies, the occurrence of PCL grafting onto the crosslinked epoxy network is known to occur via (i) amidation of PCL with the amine curing agent, (ii) the hydroxyl end groups of PCL that react with the oxirane rings of the epoxy resin, and (iii) transesterification. 15,16 Similar changes in the crystallization behavior were observed after compatibilization of polymer blends by the addition of copolymers in the absence of crosslinking. Tang and Huang 12 reported an increase in T c for blends of PP and poly(ethylene oxide) (PEO) by compatibilization with a maleated PP-PEO copolymer, whereas Adewole et al 13 observed an increase in T c for PP in blends with poly (styrene) (PS) after the addition of a PP-PS graft copolymer.…”

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confidence: 52%

“…Several studies on blends of poly(ε‐caprolactone) (PCL) with epoxy resins prepared via reaction‐induced phase separation (RIPS) showed a significant nucleating effect of the dispersed, amorphous epoxy phase on the PCL matrix 9–11. Although grafting reactions are not discussed in those studies, the occurrence of PCL grafting onto the crosslinked epoxy network is known to occur via (i) amidation of PCL with the amine curing agent, (ii) the hydroxyl end groups of PCL that react with the oxirane rings of the epoxy resin, and (iii) transesterification 15, 16. Similar changes in the crystallization behavior were observed after compatibilization of polymer blends by the addition of copolymers in the absence of crosslinking.…”

Section: Introductionmentioning

confidence: 99%

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Crystallization kinetics and crystalline morphology of poly(ε‐caprolactone) in blends with grafted rubber particles

l’Abee

Duin

Goossens

2010

J Polym Sci B Polym Phys

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The crystallization behavior of pure PCL and PCL in blends with crosslinked rubber particles was studied under (non)isothermal crystallization conditions, where the rubber particles were grafted with PCL chains via hydrogen abstraction of the aliphatic moieties in PCL. The crystal growth and the organization of crystals into spherulitic superstructures are significantly influenced by the presence of the grafted rubber particles, which act as an excellent nucleating agent for PCL.The nucleating efficiency shows an exponential dependency on the PCL grafting density and, according to an Avrami analysis, an increased PCL grafting density increases the overall crystallization rate of the PCL matrix.

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confidence: 52%

Section: Introductionmentioning

confidence: 99%

Crystallization kinetics and crystalline morphology of poly(ε‐caprolactone) in blends with grafted rubber particles

l’Abee

Duin

Goossens

2010

J Polym Sci B Polym Phys

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“…It is known, for example, that PCL becomes immiscible with certain anhydride-cured epoxy resins during polymerization, but typically remains fully miscible with amine-cured epoxy resins up to full conversion of these latter. This difference in miscibility is attributed to the presence of hydroxyl groups in the amine-cured epoxy, which are capable of forming hydrogen bonds with the ester groups of the PCL [11,12]. PIPS has nevertheless been observed in epoxy-PCL blends cured with the diamines diethyltoluenediamine (DETDA) and 4,4 0 -diaminodiphenyl sulfone (DDS), and the dependence of the morphology of DDS-cured epoxy-PCL blends on composition and cure temperature has been described in some detail by Chen and Chang [13,14].…”

Section: Introductionmentioning

confidence: 76%

“…Thermoplastics that have been demonstrated to show this type of morphology when combined with epoxy thermoset resins include polycaprolactone (PCL) [5,[11][12][13][14][15][16][17][18][19][20], poly (ether sulfone) [21][22][23], polyetherimide [24][25][26][27], poly(methyl methacrylate) [28][29][30] and polystyrene [28][29][30]. The potential of PCL for the thermal healing of epoxies stems from its low melting temperature (55°C) and high degree of thermal expansion (an increase in volume by up to 14% between room temperature and 150°C [31]), and it has also been demonstrated to be of interest for shape-memory assisted self-healing [32,33].…”

Section: Introductionmentioning

confidence: 99%

Thermal mending in immiscible poly(ε-caprolactone)/epoxy blends

Cohades

Manfredi

Plummer

et al. 2016

European Polymer Journal

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a b s t r a c tBlends of commercial epoxy monomer with a 4,4 0 -diaminodiphenylsulfone hardener and poly(e-caprolactone) (PCL) were evaluated for their potential as a self-healing matrix for fiber-reinforced composites, based on their room temperature toughness and stiffness and their capacity for healing when subjected to a moderate heating cycle. Analysis of the microstructure and thermal properties of the blends indicated three types of morphology to result from polymerization-induced phase separation during cure, depending on the PCL content, including an interconnected particulate epoxy phase and a co-continuous PCL phase above 23 vol% PCL. While the mechanical performance diminished with increasing PCL content, toughness recovery after healing at 150°C for 30 min strongly increased. Blends with 25 vol% PCL showed a healing efficiency in excess of 70%, while retaining suitable room-temperature mechanical properties (a tensile modulus of 1.5 GPa and a tensile strength of about 20 MPa), and were concluded to be promising candidates for self-healing composites.

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“…In both studied cases, RIPS occurs, so two different phases can be seen: one corresponding to the rich-PCL phase and the other one to the epoxy matrix. There are numerous PCL/TS systems that prove totally miscible blends, forming inter-penetrating network (IPN), without phase separation [18,19]. This is explained because of the pendant hydroxyl groups, resulted from the oxirane ring opening reaction with the amine curing agent, which play an important role because they form hydrogen-bonds with PCL, enhancing its solubility into the epoxy network.…”

Section: Characterizationmentioning

confidence: 99%

Influence of Morphology on the Healing Mechanism of PCL/Epoxy Blends

2020

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Polycaprolactone (PCL) is being researched as a self-healing agent blended with epoxy resins by several reasons: low melting point, differential expansive bleeding (DBE) of PCL, and reaction induced phase separation (RIPS) of PCL/epoxy blends. In this work, PCL/epoxy blends were prepared with different PCL ratios and two different epoxy networks, cured with aliphatic and aromatic amine hardeners. The curing kinetic affects to the blend morphology, varying its critical composition. The self-healing behavior is strongly affected by the blend morphology, reaching the maximum efficiency for co-continuous phases. Blends with dispersed PCL phase into epoxy matrix can also show high self-healing efficiency because of the low PCL domains that act as reservoir of self-healing agent. In this last case, it was confirmed that the most efficient self-healable blends are one whose area occupied by PCL phase is the largest. These blends remain the good thermal and mechanical behavior of epoxy matrix, in contrast to the worsened properties of blends with bicontinuous morphology. In this work, the self-healing mechanism of blends is studied in depth by scanning electron microscopy. Furthermore, the influence of the geometry of the initial surface damage is also evaluated, affecting to the measurement of self-healing efficiency.it depends on both a kinetic curing reaction and the thermodynamics of phase separation. The obtained TP/TS morphology is strongly influenced by TP fraction added. At contents lower than critical composition, the blend morphology is usually a dispersion of TP-rich domains in the TS matrix. However, at high TP percentages, a phase inversion occurs, showing TS-rich modules dispersed into a TP-rich matrix. Close to critical composition, the blend morphology can show co-continuous phases or doubled separated phases. For TS toughening, the desired morphology is the first one, TP domains dispersed into TS matrix [4,5]. The presence of low stiffness thermoplastic domains into brittle thermoset matrix induces the appearance of different toughening mechanisms, such as shear yielding, cavitation, crack deflection, crack bifurcation, and bridging, among others.However, critical compositions are being more investigated [6], in the recent years, as self-healing strategy, due to the better distribution and higher area occupied by TP phase, which really acts healable agent.Self-healing process is usually based on a mobile phase, triggered by external stimuli, which is able to transport melted TP mass to the crack site and local mending connection by chemical bonds or physical interactions. In the case of self-healable TS/TP blends, the healing process is based on the melting of the thermoplastic phase. This means that the main requirement of the TS/TP blend to show self-healing capability is the selection of a semicrystalline thermoplastic polymer, whose melting point (T m ) is significantly lower than the glass transition temperature (T g ) of the TS resin in order to promote enough flow to crack.As it is mentioned above...

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Transesterification in homogeneous poly(?-caprolactone)-epoxy blends

Cited by 21 publications

References 27 publications

Crystallization kinetics and crystalline morphology of poly(ε‐caprolactone) in blends with grafted rubber particles

Crystallization kinetics and crystalline morphology of poly(ε‐caprolactone) in blends with grafted rubber particles

Thermal mending in immiscible poly(ε-caprolactone)/epoxy blends

Influence of Morphology on the Healing Mechanism of PCL/Epoxy Blends

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