The effect of composition on the properties of nylon 612 copolymers

Abstract

SynopsisThe series of nylon 612 copolymers was synthesized from caprolactam (C) and laurolactam (L) a t 145°C. The 50/50 C/L molar ratio copolymer was found to have the minimum melting temperature (T,) for the series. The glass transition temperatures (Tg's) of the copolymers were affected by the crystallinity of the copolymers. The T ' was at a minimum for the 50/50 copolymer for crystalline samples. However, for amorphous samples there was a decrease in Tg with increasing L content. Percent crystallinity was determined by differential scanning calorimetry and X-ray techniques. I t was found that the degree of crystallinity was at a minimum for copolymers of 70/30 to 40/60 C/L ratios. Coefficients of linear thermal expansion (CLTE) were obtained for the copolymers at 10°C intervals from 20 to 70°C for dry and from 20 to 50°C for samples conditioned at 50% relative humidity and 50°C. The dry samples gave lower initial values, but had a greater temperature dependence than the conditioned samples. As expected, the CLTE was found to be lowest for samples exhibiting the highest crystallinity. The tensile strengths and moduli decreased rapidly with increasing L up to the 70/30 C/L ratio after which they remained relatively constant. Elongations reached maximums between 70/30 and 40/60 C/L ratios. An inverse relationship was found between crystallinity and impact strength.

Polyamides – Still Strong After Seventy Years

“…The powerful effect of mixing of monomers is illustrated by the results of Garner and Fasulo [173] for the combination of PA 6 and PA 12, polymerized together from a mixture of caprolactam and laurolactam. Data taken from their table of Tensile and Impact Properties are reproduced in Table 7.…”

“…Table 7. Mechanical properties of PA6/PA12 copolyamides (after Garner and Fasulo [173] ). [177,178] was expected to be followed.…”

Anionic copolymerization of nylon 6/12: A comprehensive review

“…, the same extraction process was employed to remove unreacted monomer before measuring physio‐mechanical properties. Garner and Kubota et al . investigated the properties of molded polymer samples as well.…”

“…Both of these reasons will lessen the crystal contents of the final copolymer. In higher loadings of LL content, the homogeneity of LL crystal microstructures (γ‐crystalline) may predominate the limitations of co‐crystallization occurrence and results in an increment of total crystallinity content . However, in some cases, such co‐crystallization have been reported to be negligible .…”

Anionic Nylon 6/Zinc Composite Materials: Evaluation of Thermal and Mechanical Behavior

“…Among various aliphatic polyamide matrices, nylon 6 has been one of the best choices for preparation of various types of composite materials. [8,[13][14][15] Many deficiencies of nylons can be overcome by formulation of the system containing metal particulate as fillers. [11] Through hydrolytic polymerization, nylon 6 is conventionally produced by heating at much higher temperature of 250 C, under pressure with a catalytic amount of water (5-10%) and nylon salt or aminocaproic acid as an initiator for about 12-24 h. [11] In contrast, anionic polymerization of '-caprolactam can be carried out at the rather low temperature of 150 C in the presence of a strong base as initiator.…”