Isodimorphism in Polyamide 56/Polyamide 66 Blends with Controllable Thermal and Mechanical Properties

The crystallization behaviors of polyamide 56/polyamide 66 (PA56/PA66) blends are investigated. Isodimorphism is first found in PA56/PA66 blends. The melting point, crystallization temperature, and crystallinity of the blends first decrease and then increase with the increase of PA66 content in the blends at the pseudo-eutectic point with ϕ66 = 0.5. The crystalline structure follows the dominant component in the blends. That is, PA56 phase and PA66 phase are obtained in the PA56-rich and PA66-rich blends, respectively, upon cooling the blends from the melting state. Both PA56 phase and PA66 phase are formed in PA56/PA66 blends at the pseudo-eutectic point upon cooling from the melting state. Fourier transformation infrared spectroscopy results indicate that the isodimorphic behavior is attributed to the hydrogen bonding interactions between PA56 and PA66 chains in the blends. Mechanical properties of the blends indicate that the elongation at break of the blends is tremendously enhanced without scarifying the strength and modulus of the materials. The isodimorphism of PA56 and PA66 provides a simple and promising approach for fabricating polymeric materials with versatile applications

Eco-Friendly Preparation of Hydrophobic and Flexible Nanocellulose Fibers without Further Modification

These non-modified hydrophobic and lipophilic nanocellulose fibers (CNFs) are clean and efficient and prepared using alternating boiling of biological solutions (pectin lyase and chemical additives) and weak acid solution (i.e., sodium chlorite and acetic acid), which enrich the source of nanocellulose and reduce the environmental pollution caused by the preparation process. The prepared CNFs were systematically characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrum, cellulose component analysis, small-angle X-ray scattering, X-ray diffraction, contact angle (CA), rheological energy, toxicity, and volume distribution. The best yield of CNFs was 40.64%, with a low crystallinity of 58.57% and a high volume distribution of 14%. The CNFs are extracted by this alternate cooking with weak acid solution and biological solutions, which solves the low productivity and high pollution caused by traditional inorganic chemical acid, without solid acid pollution, and meets the requirements of material cleaning and finishing. The water CA and oil CA of CNFs were 110 and 13.7°, respectively. It indicated that the CNFs prepared by this method can be hydrophobic without further modification. The CNFs are non-toxic and have good cytocompatibility based on the toxicity test result. It has a great possibility for using in the field of medical materials