To date, polylactic acid (PLA) composites with a uniform dispersion of fillers have been extensively studied. However, there is little research about the shape memory (SM) behavior of a PLA composite in which the nanoclays have a nonuniform dispersion. In this paper, the alkaline calcium bentonite (ACBT) was first modified by citric acid (CA) to improve the compatibility between bentonite (BT) and PLA. The structure of CA-modified bentonite (CABT) was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Then the CABT/PLA composite with gradient concentration of CABT in thickness direction was fabricated. Because of the good affinity between the grafted CA and the ester groups, the CABT imposed powerful restrictions on the PLA chains, which contributed to the anisotropic driving force for shape recovery. The relationship between the structure and the properties and the mechanism of anisotropic SM behavior of composite were studied.

No abstract

No abstract

High-performance flexible conductive films are highly promising for the development of wearable devices, artificial intelligence, medical care, etc. Herein, a three-step procedure was developed to produce electromagnetic interference (EMI) shielding, Joule heating, and a hydrophobic nanofiber film based on hydrolysate of waste leather scraps (HWLS): (i) electrospinning preparation of the HWLS/polyacrylonitrile (PAN)/ zeolitic imidazolate framework-67 (ZIF-67) nanofiber film, (ii) carbonization of the HWLS/PAN/ZIF-67 nanofiber film, and (iii) coating of the carbon nanofiber@cobalt (Co@CNF) nanofiber film with perfluorooctyltriethoxysilane (POTS). The X-ray diffraction results showed that metal nanoparticles and amorphous carbon had obvious peaks. The micromorphology results showed that metal nanoparticles were coated with carbon nanofibers. The conductivity and shielding efficiency of the carbon nanofiber film with 250 μm thickness could reach 45 S/m and 49 dB, respectively, and absorption values (A > 0.5) were higher than reflection (R) values for the Co@CNF nanofiber film, which indicated that the contribution of absorption loss was more significant than that of reflection loss. Ultrafast electrothermal response performances were also achieved, which could guarantee the normal functioning of films in cold conditions. The water contact angle of the Co@CNF@POTS nanofiber film was ∼151.3°, which displayed a self-cleaning property with water-proofing and antifouling. Absorption-dominant and low-reflection EMI shielding and electrothermal films not only showed broad application potential in flexible wearable electronic devices but also provided new avenues for the utilization of leather solid waste.