The morphology of the lamellae in non-isothermally crystallized linear low-density polyethylene (LLDPE), conventional high-pressure low-density polyethylene (HP-LDPE), and a highdensity polyethylene (HDPE) sample was investigated by transmission electron microscopy (TEM). LLDPE exhibits clearly two different types of lamellae, i. e., thick, long, and straight lamellae like those of HDPE, and thin, short, and curved lamellae which grow among the former ones. Also LLDPE shows the broadest distribution of the values for the lamella thickness among the three types of polyethylenes mentioned. The average lamella thickness decreases in the order HDPE > LLDPE > HP-LDPE. Fractions were used to study the effects of the kind and the degree of short chain branching (SCB) and of the molecular weight in the range from 4 100 to 3,l 16. SCB has a predominant influence on the lamella thickness as well as on the shape, while the molecular weight does not largely affect lamella thickness but affects the shape of the lamellae. Further it was revealed from TEM observation that the isobutyl branch decreases lamella thickness more effectively than does the ethyl branch. This is in accordance with results from small-angle X-ray and differential scanning calorimetry measurements.

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Poly(p-phenylene sulfide) (PPS) is a high performance polymer that has superior chemical resistance and heat stability, but its brittleness is a serious drawback for applications. The objective of this work is to improve the physical properties of PPS by incorporating a small amount of either poly(ethylene-ran-methylacrylate-ran-glycidyl methacrylate) (EMA-GMA) or poly(ethyleneran-glycidyl methacrylate)-graft-poly(methyl methacrylate) (EGMA-g-PMMA) by melt mixing under a high shear rate. It was demonstrated that the chemical reaction between PPS and EMA-GMA (or EGMA-g-PMMA) proceeded efficiently at the interface and that the domains of EMA-GMA (or EGMA-g-PMMA) were finely dispersed in the PSS matrix with size of ca 0.1-0.3 lm. The resultant copolymers formed at the interface contributed to a decrease in the interfacial tension and an increase in the interfacial adhesion so that the obtained PPS/EMA-GMA blends (or PPS/EGMA-g-PMMA blends) showed excellent mechanical properties, at the same time retaining high thermal stability. Polymer Journal ( , good electrical and electronic properties, good mold precision, and high stiffness and modulus (tensile modulus¼2600-3900 MPa). 1 The semi-crystalline PPS has a T g of 88-93 1C, T m of 280-285 1C and an equilibrium melting point of its orthorhombic crystals at 303-350 1C. 1-3 Furthermore, PPS shows extraordinary flame retardance, having a limited oxygen index of 44%, which belongs to the highest group among polymeric materials together with poly(vinyl chloride) and polyimide. 4 So taking advantage of these unique properties, PPS has been applied as an alternative material for metals and thermoset polymers; for example, automobile parts and electrical and electronics parts. 1 However, its low toughness and high brittleness, which originate from its rigid structure, are serious drawbacks, preventing further applications.Thus, in order to improve the properties of PPS, blending of PPS has been intensively studied, and can be categorized into three groups. The first group of PPS blends are formed with other high performance super-engineering plastics, such as polysulfone, 5 poly(ether sulfone) (PES) 6,7 and liquid crystalline polymers (LCPs), 8-10 which have thermal stability over 150 1C for long durations. It is reported that PPS blends having an amorphous polysulfone matrix (p50 wt% of PPS) show good tensile properties, but that blends having a PPS matrix (450 wt% of PPS) become brittle. 5 It was found that PPS and PES are partially miscible, in which PES is also an amorphous polymer having excellent mechanical properties. 6 Although mechanical proper-

Presence of water was found to be essential to maintain the Keggin structure of 12-molybdophosphoric acid (PMo12). Hydronium ion was detected by IR at high water contents. PMo12 was almost pure Brönsted acid as seen from IR spectra of adsorbed pyridine. Dependencies of the spectra on time, temperature, and presence of water were discussed in relation to the characteristic surface properties of PMo12.

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