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Abstract It is an effective strategy to improve the heat resistance of polylactide (PLA) via forming stereocomplex crystals (SCs) in poly(l -lactide) (PLLA)/poly(d -lactide) (PDLA) blend. In this work, pentearythritol (PENTA), which is an environment-friendly polyhydroxy compound for food packaging, is selected to facilitate the SC crystallization and suppress the HC crystallization for HMW PLLA/PDLA blend. Impressively, only 3 wt% PENTA is added, the exclusive SCs with high content (X c,SC = 50%) can be obtained, which exhibits a high promotion efficiency of crystallization of SCs. Interestingly, with PENTA content ascending, the crystallinity of SCs increases drastically first and then in a relatively slow manner. Furthermore, Miscibility with high content of PENTA leads to a relatively looser packing of SC lamella in the blend confirmed by scanning electron microscope (SEM) due to intercalation of PENTA between crystal lamella. The mechanism of how PENTA facilitates the formation of SCs at molecular level is also proposed in this work. Graphical abstract Image 1 Highlights • An exclusive SCs can be efficiently achieved by addition of food-contact additive of PENTA in PLLA/PDLA blend. • The enhanced mix and intermolecular interactions of PLLA and PDLA chains with PENTA results in preferred SC crystallization. • There is an interplay effect of hydrogen bonding interaction and hydrogen bonding network on the formation of SCs. • The spherulite structure of SCs with a loose packing of lamella is observed by SEM for the first time. [ABSTRACT FROM AUTHOR]

Polyamide 6 (PA6) with low moisture-sensitivity is realized by blending with poly(ethylene terephthalate) (PET), the crystal structure and morphology formed under high cooling rate and shear stress are also investigated. A pronounced reduction in the maximum water content from 9.7 to 5.6 wt% accompanying the variation of the diffusion coefficient from 1.2 × 10−6 to 5.2 × 10−7 mm2/s with the increasing of PET content is achieved. The dielectric constant decreases from 12.3 to 6.2 (@103 Hz) and the dielectric loss decreases from 0.25 to 0.13 (@103 Hz) with the increasing of PET content. The structural characterization confirms that the hydrogen-bonding interactions between PA6 and PET play a major role in the reduction of moisture-sensitivity of PA6 as well as that the evolution of the polymorphism of PA6 that the high shear stress facilitates the formation of α-form while the high cooling rate promotes the generation of γ-form. Image 1 • The moisture-sensitivity of polyamide 6 is significantly reduced. • Hydrogen-bonding interactions play a crucial role in the low moisture-sensitivity. • The properties of the blends are well preserved under exposure of water. • The structure of the blends under high cooling rate and shear stress is revealed. [ABSTRACT FROM AUTHOR]