In this work, the effect of TiO 2 addition over morphological and ultraviolet (UV) blocking properties of poly(lactic acid) (PLA) and poly(E-caprolactone) (PCL) blends was investigated. The micrographs showed a partially co-continuous structure in the PLA/PCL blend with 42/58 (wt %/wt %) and the TiO 2 nanoparticles addition leads to a structural phase inversion, i.e., continuous PCL and partially continuous PLA with a dispersed portion. TiO 2 nanoparticles were observed to be preferably localized at the interface of the two phases due to kinetic effects (large difference between the melting temperatures) and nanoparticle geometry (low aspect ratios). An adhesion improvement between the phases and morphological stability were observed with the addition of TiO 2 nanoparticles. This behavior indicates that the nanoparticles can act as compatibilizers due to their localization at the interface between the two phases. The UV light absorption and transmission percolation threshold occurred with 1.5% TiO 2 in the 42PLA/ 52PCL blend.

This work proposes modifying the adding sequence of components during the production of poly(lactic acid) (PLA) and poly(ε‐caprolactone) (PCL) ternary systems with multiwalled carbon nanotubes (CNT) or graphene nanoplatelets (GN), in order to analyze the nanoparticles’ selective localization in terms of the competition between different factors, such as kinetics, thermodynamics, rheology, and geometry. In the studied system, the PLA's viscosity is higher than the PCL's and the difference in interactions between the CNT or the GN/PLA and the CNT or the GN/PCL is small, meaning the viscosity effects could dominate. However, other factors, such as thermodynamics and geometry, can be observed to compete with the rheological factor, depending on the mixing sequences. Depending on the processing time, a competition between thermodynamics and rheological factors could be observed when the nanoparticles had contact first with the thermodynamically favored phase. The competition between geometrical and rheological factors was observed in the presence of GN in the PLA phase, in the system in which the GN was added first to the PLA phase, which is the phase of lowest affinity. POLYM. ENG. SCI., 59:323–329, 2019. © 2018 Society of Plastics Engineers

This work aims to develop multifunctional biodegradable ternary nanocomposites with heat dissipation capability. The effects of adding hexagonal boron nitride (hBN), regarding phase morphology, near-infrared radiation (NIR) reflectance and thermal conductivity of poly (ε-caprolactone) (PCL) and poly(lactic acid) (PLA) blends were investigated. The hBN nanoparticles were selectively localized in the PCL phase. Scanning electron microscopy showed that the increased hBN concentration in the PCL/PLA blend led to a more fibrillar PLA phase and, after compression molding, its morphology presented a co-continuous structure. Adding hBN nanoplatelets increased the reflectance in the NIR region by 184%, the thermal conductivity of the PCL/PLA by 400%, and increased the blend's thermal stability. The co-continuous morphology could favor the heat flow, because it promotes the confinement of the hBN nanoplatelets in the PCL phase, favoring the conductive thermal pathway formation. POLYM. COMPOS., 40:3464-3471, 2019.

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.

The objective of this paper is investigating the effect of different localizations of titanium dioxide (TiO 2) and hexagonal boron nitride (hBN) nanoparticles in the poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blends on the ultraviolet (UV) blocking, infrared reflection (NIR), and thermal conductivity of the nanocomposites for the fabrication of bionanocomposites with high performance. Transmission electron microscopy images demonstrated that the different mixing sequences induced different nanoparticle localization in the immiscible PCL/PLA blend. These different localizations yielded differences in the properties of the hybrid quaternary nanocomposite. When the nanoparticles had different localizations, TiO 2 at the interface and hBN in the PCL phase, the thermal conductivity was 0.86 Wm −1 K −1 , 100% of UV radiation (λ = 300 nm) was blocked and 74% of NIR radiation was reflected. This nanocomposite has a strong potential for application as a multifunctional biodegradable film for agriculture, capable of absorbing UV radiation, reflecting NIR radiation, and conducting thermal energy.