Crystallization and Melting Behavior of Nylon 66/Poly(ether imide) Blends

Abstract

ABSTRACT:Isothermal crystallization and melting behavior of nylon 66 and its blends with poly(ether imide) (PEI) were investigated by differential scanning calorimetry. Crystallization kinetics such as overall rate constant Z and index n were calculated according to Avrami approach. Crystallization in the blend was retarded with respect to that of pure nylon 66 by incorporation of PEI with high glass transition temperature (T.). The lowest growth rate of the spherulites was observed in the blends containing 10 and 15wt% fraction of PEI. A transition temperature where positively birefringent spherulites disappear and negative birefringent spherulites develop was measured by thermal analysis. The transition temperature increased with content of PEI in the blends. A suitable range of isothermally crystallization temperatures, 238.5-246°C, is suggested for determining the equilibrium melting points by means of Hoffman-Weeks approach.KEY WORDS Crystallization Behavior / Melting / Polymer Blend / Nylon 66/Poly(ether imide) / Poly(ether imide), PEI, (poly(2,2'-bis(3,4-dicarboxyphenoxy)phenyl propane)-2-phenylene bisimide), is a relatively new high performance material with the repeat unit:It is a thermally stable, non-crystallizable and soluble thermoplastic manufactured by General Electric Co. Key properties of PEI are excellent high temperature resistance, toughness, good dielectric properties, low flammability, and high resistance to radiation and deformation under load at elevated temperatures. In particular, PEI combines relatively low production cost with appreciable physical properties. 1 -3 Some basic research on the blends of PEI with thermotropic liquid crystalline polymers, 4 polyetheretherketone, 5 polyethersulfone, 6 and polybenzimidazole 7 has been carried out.Aliphatic polyamides are extensively used in the manufacture of automobile parts, engineering products, and textile fibers. Among various polyamides, nylon 66 and nylon 6 are commercially important polyamides. Nylon 66 is a crystallizable material with relatively high mechanical properties, low cost, and low melting viscosity. Blending nylon 66 with a variety of polymers has generated considerable interest because this is an easy way of tailoring nylon 66 to suit specific end uses. Sometimes, it made blends of nylon 66 with novel mechanical performance and excellent processing properties. Significant improvement in processing properties of PEI can be achieved without a consequent decrease in the mechanical properties by blending a small amount of nylon 66 with PEL The mechanical and heat resistant properties of nylon 66 increase remarkably by adding PEI as a minor component. Thus, blending the two polymers seems most attractive in terms of both processability and performance improvement.Numerous works have been reported on polyamides regarding melting behavior, 8 • 9 crystal structures, 10 , 11 spherulitic morphologies, 12 • 13 as well as the reorganization of crystals on heating, 14 but study of crystallization and melting behavior of nylon blends,...

Crystallization kinetics of polyamide 66 at processing-relevant cooling conditions and high supercooling

“…7 is a plot of the peak-time of isothermal crystallization of PA 66 as a function of the crystallization temperature. The blue and red circles represent peak times of crystallization obtained by FSC in this work while the other symbols represent half-times of crystallization collected by DSC on different PA 66 grades, available in the literature [29][30][31]. As discussed above, the peak-time of crystallization decreases with increasing supercooling due to increasing thermodynamic driving for the crystallization, passes through a minimum at 160-170 C, and begins then to increase because of decreasing mobility of chain segments (see red data points and arrow) [53,54].…”

“…Regarding the kinetics of formation of a 0 -crystals it is known that on cooling at rates lower than 20 K/min, as is typically applied in DSC analyses, crystallization occurs at 220-240 C [23][24][25][26][27][28][29]. Isothermal DSC experiments revealed that at a temperature of 230 C crystallization is finished after about 1-2 min, with the crystallization time rapidly increasing with crystallization temperature [29][30][31]. Besides formation of the a-polymorph as a result of slow cooling or crystallization at high temperature, there has been reported the development of a pseudohexagonal mesophase with non-planar arrangement of hydrogen bonds upon quenching of the melt [32].…”

“…Blue and red circles represent peak times of crystallization obtained by FSC in this work while the other symbols represent half-times of crystallization collected by DSC, reported in literature[29][30][31]. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.…”

Effect of compatibilization on the properties of HIPS/PA1010 blends

“…8 It seems that the crystals formed at a lower T c usually contain a bit of smaller and more defective spherulites. Perhaps most of them are positive spherulites with branched fibril structure.…”

Structure and Mechanical Properties of Directly Injection‐Molded Blends of Poly(ether imide) and Polysulfone of Bisphenol A

“…Partially miscible blends, include blends with poly(ethylene terephthalate),11 bisphenol A polycarbonate12 and polyarylate 13, 14. Other blends, such as those with poly(phenylene sulfide),15 polyamide 6,616, 17 and liquid crystal polymers 18, 19 were reported to be immiscible.…”