Influence of properties and morphology of elastomeric phase on the behavior of ternary reactive blends of polyamide 6/rigid polymer/elastomer

Abstract

A ternary blend of the PA6 matrix with a finely dispersed rigid polymer and elastomer is a system with well-balanced mechanical properties. Its micromechanical behavior, especially that of the elastomer phase, apparently differs from corresponding binary mixtures. This study shows the influence of the elastomer type, modulus, and reactivity on the behavior of ternary blends in comparison with analogous binary PA6/elastomer combinations. The presence of rigid reactive poly(styrene-co-maleic anhydride) (SMA) enhanced the properties of all the systems studied. For nonreactive elastomers, the dominant effect was refinement of their size due to enhanced viscosity, whereas for functionalized low-modulus elastomers, the very good balance of properties was due to synergistic influences of both finely dispersed phases. Of interest is the enhanced toughness of ternary blends also for more rigid elastomers having a low toughening efficiency in binary blends. An appropriate addition of rigid SMA together with an elastomer enhances the energy absorption of the matrix, probably without cavitation of very small elastomer particles. Of importance also is the simultaneous strain-hardening effect of deformed rigid particles.

PBT blends with rigid polymer and elastomer inclusions: the effect of component type and reactivity on mechanical behaviour

“…The most favourable behaviour, ie simultaneous enhancement of strength, modulus and impact strength, was found for the blends with the finest dispersion of both components, ie those containing at least one component bearing epoxy functionality, e.g., the EPR‐MA/PS‐co‐GMA/PBT and PE‐GMA/PS‐GMA/PBT systems. The fact that the best ternary blend contained the finest particles agrees to the results obtained for PA6 blends12–14 and confirms the best effectivity of a combination of rigid and brittle inclusions in this case. Unfortunately, due to lower effectivity of reactive compatibilization of PBT, the particle size of most systems studied exceeded the optimum value ≈0.1 µm 12–14.…”

“…This is undoubtedly the main reason for the lowest size of elastomer particles, 0.2 µm (close to that of the analogous PA6 blend), found in the presence of the most reactive PS‐ co ‐GMA (particle size ≈0.1 µm), whereas for other less reactive rigid components, significantly larger elastomer particles occur. In comparison with analogous PA6 systems with particle size of both dispersed components below 0.1 µm,12–14 the structure of PBT systems (Table 1) is coarser as a consequence of the less effective reactive compatibilization of the used components with PBT.…”

“…It can be seen that the size of elastomer particles in ternary blends in all cases is lower in comparison with corresponding binary blends. One reason is a lower elastomer content (5 % versus 10 %) but, in the case of fair reactivity of the second (rigid) component, the effect of increased viscosity should also be taken into account 14. This is undoubtedly the main reason for the lowest size of elastomer particles, 0.2 µm (close to that of the analogous PA6 blend), found in the presence of the most reactive PS‐ co ‐GMA (particle size ≈0.1 µm), whereas for other less reactive rigid components, significantly larger elastomer particles occur.…”

“…Recently, we have found a good balance of mechanical properties in toughened Polyamide 6 (PA6) system by replacing a part of the elastomer with finely dispersed rigid polymer 12–14. An example is the PA6/poly(styrene‐ co ‐maleic anhydride) (SMA)/maleated ethylene‐propylene elastomer (EPR‐MA) combination, where up to 15 % total content of both dispersed components, an increase in toughness, strength and at least unchanged stiffness was found.…”

Polymer Blends

“…To achieve their separate dispersion, the surface energy of one minority component should be higher than that of the matrix, while the reverse relation holds for the other minority component (242). Ternary blends of polyamide 6 containing rigid particles of SMA ($5%) and particles of maleated ethylenepropylene rubber ($5%) are an example of blends with balanced mechanical properties (286,287). In these blends, the losses in stiffness and tensile strength caused by rubbery component are (more than) compensated by the action of the brittle component, while both minority components contribute to the toughness enhancement.…”