The morphology of polyamide 6/poly(butylene terephthalate) (PA6/PBT, 70/30, W/W) blends filled with pristine Zinc oxide (ZnO) nanoparticles and ZnO surface-modified by γ-glycidoxypropyltrimethoxysilane (K-ZnO) was investigated. The incorporation of ZnO and K-ZnO by one-step compounding both resulted in a smaller size and narrower distribution of PBT domains and the effect of ZnO was greater than K-ZnO. To reveal the underlying mechanism, two-step compounding in which ZnO or K-ZnO was premixed with PA6 or PBT was conducted and the finest morphology was achieved when mixing PA6 with premixed PBT/ZnO. Transmission electron microscopy (TEM) demonstrated that ZnO was distributed in PBT in all cases and K-ZnO was enriched at the interface except when K-ZnO was premixed with PBT. ZnO and K-ZnO caused a deterioration in the melt rheological properties of PBT, which played a dominating role in the morphological changes. In addition, the interfacial localization of K-ZnO enhanced the dynamic rheological properties of PA6/PBT blends substantially.

The morphology and properties of polyamide 6 (PA6)/poly(butylene terephthalate) (PBT) blends filled by three types of glass fibers (GF) with different surface properties were investigated. The GF were unmodified or surface-modified for PA6 or PBT, denoted as GF(Pris), GF(PA6), and GF(PBT), respectively. The incorporation of 15 wt % of GF with different surface properties all led to a transition from a cocontinuous (at least a part of each phase penetrates the whole volume in a coherent and continuous manner) to a sea-island (separated domains dispersed in a continuous matrix) morphology with PA6 being the matrix phase when PA6/PBT equaled 45/55. GF(Pris) was always encapsulated by PA6, while the encapsulating layers on the surfaces of GF(PA6) and GF(PBT) changed from PBT to PA6 with increasing PA6 contents. The morphological changes induced by GF caused more PBT to crystallize at a lower temperature and enhanced the alkali tolerance of the blend significantly.