SOLUBILITY OF NYLON 3

As nylon 3 melts at about 340°C with decomposition, melt spinning of nylon 3 may be difficult. Therefore, wet spinning or dry spinning must be used for production of nylon 3 fibers. In order to get the basic information of solution spinning of nylon 3, its solubillity is investigated in this paper.The solvent power of aqueous inorganic salts depends strongly on the combination of both cation and anion. Salts containing such cations as Zn2+, Sn4+, Mg2+, Li+, Ca2+, Fe3+ and such anions as SCN-, ClO4-, I-, Br-, Cl-, are good solvents for nylon 3. Strong inorganic acids (e. g. sulfuric acid, nitric acid) are also solvents. Phenol and m-cresol, which are usually good solvents for polyamides, have poor solvent power for nylon 3. Compounds with electron accepting substituent groups (e. g. p-nitrophenol, m-nitrophenol, trichloroacetaldehyde, cyanoacetic acid) have good dissolving power to nylon 3. Some mixed organic solvents such as phenol-water, chloral hydratewater systems also have good dissolving power for nylon 3. Organic compounds, which are known to be proton acceptors (e. g. dimethylformamide, dimethyl sulfoxide) do not dissolve nylon 3. Dissolving mechanism of nylon 3 was investigated by an infrared spectroscopy, using N-methy-lacetamide as a model compound of nylon 3, and is explained in terms of proton donating power of the solvents to nylon 3.