Blends of nylon-6 and EPDM-rubber were prepared with various rubber contents (0-20 wt ~o) and particle sizes (0.3-1.6 #m). The effects of rubber concentration and particle size on the tensile modulus, torsion modulus, yield stress and notched impact strength of the blends were studied. Blend structures and fracture surfaces were investigated by scanning electron microscopy. Rubber particles induce a sharp brittle-tough transition which is independent of the glass transition temperature of the nylon matrix. The brittle-tough transition temperature for notched Izod impact tests shifts to lower values when the rubber content is increased or the particle size is decreased. A correlation was found between the brittle-tough temperature and the interparticle distance. Two deformation modes were observed: voiding and shear yielding. Particle size and interfacial adhesion affect neither the yield stress nor the modulus of the blends.

Blends of 90wt% nylon-6 and 10wt% impact modifier were prepared. As impact modifiers were used: EPDM (ethylene propylene diene monomer) rubber, EPM (ethylene propylene monomer) rubber, polyethylene, four poly(ether esters) and some commercial impact modifers. EPDM, EPM and polyethylene were functionalized with maleic anhydride. The mechanical properties of the impact modifiers were tested with both a torsion pendulum test and a tensile test. The notched impact strength of the blends was measured as a function of temperature. The relation between the mechanical properties of the elastomer and the impact behaviour of the elastomer-modified nylon-6 was studied while taking into account the effect of the rubber particle size. The type of impact modifier was found to have a strong effect on the impact behaviour of the blend. The rubber particles do not toughen nylon-6 by acting as stress concentrators.

SynopsisNylon 46 was synthesized from the salt of l,4-diaminobutane and adipic acid. High molecular weight polymers could be obtained by reaction for 1 hr at 215OC in a closed system and at least for 1 hr in UQCUO at a temperature in the range 290-305OC. The reactions at 29OOC were found to have taken place in the solid state and those at 305OC in the melt. The highest molecular weights ( M , ca. 45,000) were obtained by reaction at 290°C with a nylon salt with a pH of 7.8-8.0. The molecular weight characteristics were studied with end-group analysis, viscometry, light scgtering, and ultracentrifugation. The polymers were found to be gel-free and monodisperse (M,/Mn -1.15).Films could be cast from formic acid. From x-ray diffraction patterns, measured on such films, spacings of 3.74 and 4.30 A were calculated, whereas a long period of 66 A was also found. The infrared spectra showed all the usual amide bands of even-even polyamides. The melting temperature was found to vary between 283 and 319OC, depending on the thermal history of the sample. Water absorption measured on a cast film showed this to be very hygroscopic (7.5% at 65% RH), while a highly crystalline sample absorbed only little water (1.6% at 65% RH).

SynopsisNylon 46 was synthesized from the salt of l,4-diaminobutane and adipic acid. High molecular weight polymers could be obtained by reaction for 1 hr at 215OC in a closed system and at least for 1 hr in UQCUO at a temperature in the range 290-305OC. The reactions at 29OOC were found to have taken place in the solid state and those at 305OC in the melt. The highest molecular weights ( M , ca. 45,000) were obtained by reaction at 290°C with a nylon salt with a pH of 7.8-8.0. The molecular weight characteristics were studied with end-group analysis, viscometry, light scgtering, and ultracentrifugation. The polymers were found to be gel-free and monodisperse (M,/Mn -1.15).Films could be cast from formic acid. From x-ray diffraction patterns, measured on such films, spacings of 3.74 and 4.30 A were calculated, whereas a long period of 66 A was also found. The infrared spectra showed all the usual amide bands of even-even polyamides. The melting temperature was found to vary between 283 and 319OC, depending on the thermal history of the sample. Water absorption measured on a cast film showed this to be very hygroscopic (7.5% at 65% RH), while a highly crystalline sample absorbed only little water (1.6% at 65% RH).

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