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ABSTRACT:We have investigated polyketone (PK)/ polyamide 6 (PA) polymer alloys having enhanced Charpy impact energy greater than that of polycarbonate (PC) as a result of moisture absorption. From the results of differential scanning calorimetry (DSC), Raman spectroscopy, and transmission electron microscope (TEM) observation of the polymer alloys, it was found that PK-rich and PA-rich phases exist at the nanometer level in the polymer alloys; however, a microscopic interaction phase formed between the two phases. 3D-TEM observations, electron energy loss spectroscopy, and small-angle X-ray scattering measurements revealed that a co-continuous nanolayer formed from the PA-rich phase and lamella network of the PKrich phase. Moreover, the interaction and mobility of PK and PA molecular chains were investigated by using a 13 C cross polarization/magic angle sample spinning NMR technique. It was found that moisture absorption markedly enhances the mobility of PA molecular chains in PK/PA alloys. This suggests that the wet (moisture-absorbed) PA phase of PK/PA alloys allows quick deformation upon impact stimulation. On the other hand, the results of Charpy impact tests showed that the total impact energy (E total ) of the wet polymer alloy was much higher than that of the dry one. An examination of the load-displacement curves revealed that the wet samples showed a pronounced increase in displacement compared with the dry ones. From these results, it was concluded that the lamella network of the PK-rich phase sustains the maximum stress and that the large displacement of the PA-rich phase increases the impact energy.

The influence of diblock copolymer addition on the tack properties of a polyacrylic triblock copolymer/tackifier system was investigated. For this purpose, poly(methyl methacrylate)‐block‐poly(n‐butyl acrylate)‐block‐poly(methyl methacrylate) triblock copolymer (MAM) and a 1/1 blend with a diblock copolymer consisting of the same components (MA) were used as base polymers, and a tackifier was added in amounts ranging from 10 to 30 wt %. The temperature dependence of tack was measured by a probe tack test. The tack of MAM/MA at room temperature was significantly higher than that of MAM, and the improvement of MAM/MA upon the addition of the tackifier was higher than that of MAM. The peeling process at the probe/adhesive interface during the probe tack test was observed using a high‐speed microscope. It was found that for MAM/MA, cavitation was caused in the entire adhesive layer, and peeling initiation was delayed by the absorption of strain energy due to deformation of the adhesive layer. In contrast, for MAM, peeling progressed linearly from the edge to the center of the probe. The greater flexibility of the soft block chain in the diblock copolymer resulted in improved interfacial adhesion. 1H pulse nuclear magnetic resonance analysis showed that the addition of the tackifier improved the cohesive strength of the adhesive. Adhesion strength is affected by two factors: the development of interfacial adhesion and cohesive strength. In the MAM/MA/tackifier system, the presence of MA and the tackifier improved the interfacial adhesion and cohesive strength, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

ABSTRACT:The Izod impact strength of two kinds of ternary composites was investigated. One consisted of polypropylene (PP), the triblock copolymer polystyreneblock-poly(ethylene butene)-block-polystyrene (SEBS), and calcium carbonate (CaCO 3 ) particles, and the other consisted of PP, carboxylated SEBS (C-SEBS), and CaCO 3 particles. The mean size of the CaCO 3 particles was about 160 nm. According to scanning electron microscopy observations, the composite with SEBS showed a morphology in which SEBS domains and CaCO 3 particles were independently dispersed in the PP matrix. On the other hand, the composite with C-SEBS showed a morphology in which CaCO 3 particles were encapsulated by C-SEBS; that is, a core-shell structure was formed. The Izod impact strength of the composite with SEBS was higher than that of the composite with C-SEBS and the PP/SEBS and PP/C-SEBS binary blends. According to observations of the fractured surface, the stress-whitened area was larger in the composite with SEBS than in the composite with C-SEBS and the PP/SEBS and PP/C-SEBS binary blends. The toughening mechanism of the composite, using nanometer-sized CaCO 3 particles in combination with SEBS, was examined.

Nagata et al. recently developed high-impact polyketone/polyamide-6 (PK/PA) alloys and investigated their mechanical properties (Nagata et al. Polym. Prep. Jpn. 2006, 55, 4286−4287). This paper presents the results of investigations of their morphology, such as the domain size of PA and PK, features of crystalline phase of PK (the long period and thickness of lamellae are deduced), and the change in crystalline form of PA in the PK/PA alloys, using solid-state nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Solid-state 13C and 15N NMR results revealed that the γ crystalline phase of PA changes into a thermodynamically stable α crystalline phase after alloying with PK. The difference in the long period of lamellae of PK/PA alloys between dry and wet conditions is discussed. We conclude that the characteristic morphology of PK and humidity of the amorphous phase of PA in the wet condition are very important factors enabling the PK/PA alloys to exhibit high impact resistance, high-strength, and high modulus.