Effects of processing conditions on hybrid filler selective localization, rheological, and thermal properties of poly(ε‐caprolactone)/poly(lactic acid) blends

Abstract

In this study, the effects of processing conditions through different mixing sequences were used to analyze the factors, which could influence the hybrid filler selective localization in an immiscible polymer blend and how localization can influence the rheological and thermal properties. Different selective localizations were observed depending on the mixing sequence used when the hybrid filler was added. Notably, nanoparticles can interact with each other, which favor a synergy between them and alters, besides the localization, the dispersion state, or can interact with one polymer phase, and also alter the nanoparticles' selective localization. An improvement in rheological properties was observed in the hybrid nanocomposite in which there was interaction between the nanoparticles, favoring the hexagonal boron nitride exfoliation. On the other hand, for the storage modulus and degree of crystallinity, the sharpest increase occurred in the hybrid nanocomposite in which the nanoparticles could interact preferably with one polymer phase. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48711.

Multifunctional bionanocomposites with ultraviolet blocking, infrared reflection and thermal conductivity

“…[ 38 ] In the samples after the compression process, as there is no longer a preferential direction forced by the processing/flow, the elongated fibrillar phase is randomly oriented in space (as highlighted by the rows), Figure 1D‐F, suggesting that hybrid quaternary nanocomposites have a co‐continuous‐like morphology (composed of discontinuous irregular PLA domains, distributed in the PCL continuous matrix). [ 39,40 ] Figure 2 presents the TEM image and as previously observed in Aguiar et al [ 41 ] the light phase is the PLA and dark phase the PCL. In previous studies individually adding the nanoparticles to the PCL/PLA system, [ 5,6 ] a co‐continuous‐like structure was observed and the TiO 2 preferred localization was at the interface, [ 5 ] while the hBN was in the PCL phase.…”

“…The nanocomposites crystallinity was discussed in our previous paper. [39] The opaquest film, PCL/PLA/hBN + TiO 2 , showed the highest crystallinity degree (37%,) and PCL/PLA/TiO 2 /hBN, the most translucent, presented 17% of crystallinity degree. [39] Analyzing the behavior of hybrid quaternary nanocomposites in the NIR wavelength region, in the reflectance spectrum ( Figure 5C), the PCL/PLA/TiO 2 / hBN nanocomposite had a lower NIR reflectance capacity (54%) than the PCL/PLA/TiO 2 + hBN and the PCL/ PLA/hBN + TiO 2 nanocomposites ( Figure 6B).…”

“…[39] The opaquest film, PCL/PLA/hBN + TiO 2 , showed the highest crystallinity degree (37%,) and PCL/PLA/TiO 2 /hBN, the most translucent, presented 17% of crystallinity degree. [39] Analyzing the behavior of hybrid quaternary nanocomposites in the NIR wavelength region, in the reflectance spectrum ( Figure 5C), the PCL/PLA/TiO 2 / hBN nanocomposite had a lower NIR reflectance capacity (54%) than the PCL/PLA/TiO 2 + hBN and the PCL/ PLA/hBN + TiO 2 nanocomposites ( Figure 6B). Sun reflectance occurs on the surface of the samples, and as the nanocomposites exhibited a co-continuous-like morphology with different localizations of the TiO 2 and the hBN nanoparticles, some areas of the film may have been uncovered, that is, without nanoparticles, allowing the F I G U R E 6 A, Blocking UV-B (300 nm wavelength) of films; B, Reflectance NIR (1000 nm wavelength) of films.…”

“…Thus, for these hybrid quaternary nanocomposites, the mixing sequence altered the migration dynamics of the hBN and the TiO 2 nanoparticles, that is, it had a direct influence on the localization of the TiO 2 /hBN hybrid in the PCL/PLA blend. In the study by Decol et al, [ 39 ] the factors that influenced the localizations were discussed, highlighting that nanoparticles can strongly interact with each other, which may favor the synergy between them by changing the dispersion state, or they can interact with a polymer phase, changing the selective localization of nanoparticles. Thus, nanoparticle/nanoparticle and/or nanoparticle/polymer interaction can influence the selective localization and dispersion of hybrid nanoparticles in an immiscible blend.…”

“…The nanocomposites crystallinity was discussed in our previous paper. [ 39 ] The opaquest film, PCL/PLA/hBN + TiO 2 , showed the highest crystallinity degree (37%,) and PCL/PLA/TiO 2 /hBN, the most translucent, presented 17% of crystallinity degree. [ 39 ]…”