Search Results (3)

Nylon 514 is one of the new long-chain bio-based nylon materials; its raw material, 1,5-pentanediamine (PDA), is prepared by biological techniques, using biomass as the raw material. The high-performance monomer of nylon 514, 1,5-pentanediamine-tetradecanedioate (PDA-TDA) salt, was obtained through efficient crystallization methods. Here, two crystal forms of PDA-TDA, anhydrous and dihydrate, were identified and studied in this paper. From the characterization data, their crystal structures and thermal behaviors were investigated. Lattice energy was calculated to gain further insight into the relationship between thermal stability and crystal structures. The contribution of hydrogen bonds and other intermolecular interactions to the crystal structure stability have been quantified according to detailed Hirshfeld and IRI analyses. Additionally, the transformation mechanism of the anhydrate and dihydrate was established through a series of well-designed stability experiments, in which the temperature and water activity play a significant role in the structural stability of crystalline forms. Eventually, we obtained nylon 514 products with good thermal stability and low absorption using stable dihydrate powders as monomers. The properties of nylon 514 products prepared by different polymerization methods were also compared. Full article

Bio-based polymers can reduce dependence on nonrenewable petrochemical resources and will be beneficial for future sustainable developments due to their low carbon footprint. In this work, the feasibility of bio-based polyamide 56 (PA56) substituting petroleum-based PA66 is systematically investigated. The crystallization, melting, and decomposition temperature of PA56 were all lower than that of PA66. PA56 formed a γ crystal type with larger grain size and took a longer amount of time to complete the crystallization process since its crystallization rate was lower than that of PA66. Compared with PA66, PA56 exhibited a higher tensile strength of 71.3 ± 1.9 MPa and specific strength of 64.8 ± 2.0 MPa but lower notched impact strength. More importantly, the limited oxygen index and vertical combustion measurement results indicated that the flame retardancy of PA56 was better than PA66, and the LOI values and the UL94 result of PA56 were 27.6% ± 0.9% and V-2. It is worth noting that the PA56 fiber had superior biodegradability compared to the PA66 fiber. PA56 showed significant biodegradation from the eighth week, whereas PA66 remained clean until the sixteenth week (without obvious biodegradation taking place). Eventually, PA56 did not show significant differences compared to PA66 in terms of thermal and mechanical properties. However, PA56 had great advantages in flame retardancy and biodegradability, indicating that the bio-based PA56 could potentially replace petroleum-based PA66 in many fields. Full article

In this work, solubility data of 1,5-pentanediamine adipate dihydrate in binary solvent systems of water + methanol, water + ethanol and water + N,N-dimethylformamide were experimentally measured via a static gravimetric method in the temperature range from 278.15 K to 313.15 K under atmospheric pressure. The results indicated that the solubility of 1,5-pentanediamine adipate dihydrate increased with the rising of temperature in all the selected binary solvent systems. For water + N,N-dimethylformamide, solubility increased as the mole fraction of water increased. However, the rising tendency changed when the temperature was higher than 303.15 K for water + methanol, and it would show a cosolvency phenomenon for water + ethanol. Furthermore, the solubility data were fitted with modified an Apelblat equation, NRTL model, combined nearly ideal binary solvent/Redlich Kister (CNIBS/R-K) model and Jouban–Acree model. The calculation results agreed well with the experimental data. Finally, the mixing thermodynamic properties of 1,5-pentanediamine adipate dihydrate in all tested solvents were calculated based on the experimental data and NRTL model. Full article