The mechanism and energy of activation of the melting of poly (ε‐caprolactone) with and without prior treatment with span 80

Fraga, F.; Martínez-Ageitos, J. M.; Rodríguez‐Núñez, Eugenio; Blanco-Méndez, J.; Luzardo-Álvarez, Asteria; Calvo-Carnota, Emilio; Jiménez-Carrillo, Lisbeth

doi:10.1002/app.34164

Cited by 4 publications

(7 citation statements)

References 34 publications

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“…A p and E p stand for the pre‐exponential constant and the activation energy of the melting, respectively. [ 18 ] The material properties and the parameters entered in the cure and melting kinetics models used in the present study are summarized in Tables 1 and 2 , respectively. When compared with experiments, an additional heat loss term − H loss ∙ ( T − T 0 ) was added to the left‐hand side of the first equation in Equations () and (), where H loss = 24.5 kW m −3 is the heat loss coefficient and was determined by fitting the local temperature history in experiments (Figure S9, Supporting Information).…”

Section: Methodsmentioning

confidence: 99%

Controllable Frontal Polymerization and Spontaneous Patterning Enabled by Phase‐Changing Particles

Gao

Dearborn

Hemmer

et al. 2021

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Frontal polymerization provides a rapid, economic, and environmentally friendly methodology to manufacture thermoset polymers and composites. Despite its efficiency and reduced environmental impact, the manufacturing method is underutilized due to the limited fundamental understanding of its dynamic control. This work reports the control and patterning of the front propagation in a dicyclopentadiene resin by immersion of phase‐changing polycaprolactone particles. Predictive and designed patterning is enabled by multiphysical numerical analyses, which reveal that the interplay between endothermic phase transition, exothermic chemical reaction, and heat exchange govern the temperature, velocity, and propagation path of the front via two different interaction regimes. To pattern the front, one can vary the size and spacing between the particles and increase the number of propagating fronts, resulting in tunable physical patterns formed due to front separation and merging near the particles. Both single‐ and double‐frontal polymerization experiments in an open mold are performed. The results confirm the front–particle interaction mechanisms and the shapes of the patterns explored numerically. The present study offers a fundamental understanding of frontal polymerization in the presence of heat‐absorbing second‐phase materials and proposes a potential one‐step manufacturing method for precisely patterned polymeric and composite materials without masks, molds, or printers.

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Section: Methodsmentioning

confidence: 99%

Controllable Frontal Polymerization and Spontaneous Patterning Enabled by Phase‐Changing Particles

Gao

Dearborn

Hemmer

et al. 2021

Small

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“…Koocheki et al reported a reduction in the T g of PLGA due to the interaction between the Tween 80 and polymer molecules 39 . Fraga‐López et al demonstrated the plasticizer effect of Span 80 when studying the influence of this surfactant in the melting activation energy of poly(ε‐caprolactone) 45 …”

Section: Resultsmentioning

confidence: 99%

“…39 Fraga-López et al demonstrated the plasticizer effect of Span 80 when studying the influence of this surfactant in the melting activation energy of poly(ε-caprolactone). 45 Carefully observing the results shown in Figure 13, it was noticed that the T g of PLLA microparticles produced with Span 80 were lower than those produced with Tween 80. A more intense plasticizer effect was expected when using Span 80 instead of Tween 80 due to the low HLB (4.3) of Span 80, which characterizes it as a hydrophobic compound.…”

Section: Thermal Characterization Of the Microparticlesmentioning

confidence: 85%

Metformin hydrochloride sustained release biopolymeric system composed by PLLA‐CMC microparticles

Silva

Nogueira

2021

J of Applied Polymer Sci

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Metformin hydrochloride (MetHCl) is a drug extensively used to treat diabetes mellitus Type 2. However, its high hydrophilicity drastically reduces its metabolic absorption. Consequently, high drug concentrations should be taken by patients to achieve the desired therapeutical efficiency, causing several side effects. The present study proposes the development of a MetHCl sustained release biopolymeric system composed of poly(L-lactic acid) (PLLA) and carboxymethyl cellulose (CMC) as a strategy to minimize the problems aforementioned. The PLLA-CMC microparticles were produced by the double emulsion-solvent evaporation technique using two distinct emulsifiers in the first emulsion (Span 80 and Tween 80). The microparticles were characterized by ultraviolet-visible spectrophotometry, scanning electron microscopy with field emission gun, thermogravimetric analyses, and differential scanning calorimetry (DSC). Additionally, in vitro drug release assays were performed. The results demonstrated that the emulsion stability and encapsulation efficiency increased in a dependent fashion way with the CMC concentration. DSC findings showed that the choice of the emulsifier of the first emulsion influences the polymer particle's crystallinity and, consequently, the releasing behavior of the drug. The in vitro studies revealed that the encapsulation of MetHCl in PLLA-CMC microparticles is a promising sustained release system compatible with a zero-order kinetic mechanism.

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“…The solution in discrete phase-changing PCL particles (denoted hereafter with the subscript p) is obtained with the aid of the following melting–diffusion model describing the evolution of the degree of melting δ In the first equation, H p denotes the melting enthalpy and the negative sign reflects the endothermic nature of the melting process. The second equation approximates the phase transition of the PCL as a first-order kinetic model, where A p and E p , respectively, stand for the pre-exponential constant and the activation energy of the melting process. , The thermal properties and melting kinetics parameters are listed in Tables and , respectively.…”

Section: Computational and Experimental Methodsmentioning

confidence: 99%

“…The second equation approximates the phase transition of the PCL as a first-order kinetic model, where A p and E p , respectively, stand for the pre-exponential constant and the activation energy of the melting process. 37,39 The thermal properties and melting kinetics parameters are listed in Tables 1 and 2, respectively. Equations 1 in the COD resin and eq 3 in the part of the domain occupied by the embedded PCL particles are solved in the rectangular domain shown schematically in Figure 2a while maintaining the particle volume fraction ϕ fixed (ϕ = 0.1).…”

Section: ■ Introductionmentioning

confidence: 99%

Manipulating Frontal Polymerization and Instabilities with Phase-Changing Microparticles

et al. 2021

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Recently presented as a rapid and eco-friendly manufacturing method for thermoset polymers and composites, frontal polymerization (FP) experiences thermo-chemical instabilities under certain conditions, leading to visible patterns and spatially dependent material properties. Through numerical analyses and experiments, we demonstrate how the front velocity, temperature, and instability in the frontal polymerization of cyclooctadiene are affected by the presence of poly(caprolactone) microparticles homogeneously mixed with the resin. The phase transformation associated with the melting of the microparticles absorbs some of the exothermic reaction energy generated by the FP, reduces the amplitude and order of the thermal instabilities, and suppresses the front velocity and temperatures. Experimental measurements validate predictions of the dependence of the front velocity and temperature on the microparticle volume fraction provided by the proposed homogenized reaction−diffusion model.

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The mechanism and energy of activation of the melting of poly (ε‐caprolactone) with and without prior treatment with span 80

Cited by 4 publications

References 34 publications

Controllable Frontal Polymerization and Spontaneous Patterning Enabled by Phase‐Changing Particles

Controllable Frontal Polymerization and Spontaneous Patterning Enabled by Phase‐Changing Particles

Metformin hydrochloride sustained release biopolymeric system composed by PLLA‐CMC microparticles

Manipulating Frontal Polymerization and Instabilities with Phase-Changing Microparticles

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