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The RTPP/ABS (rubber toughened polypropylene/poly (acrylonitrile-co-butadiene-co-styrene) blends, both noncompatibilized and compatibilized with polypropylene-g-polystyrene, were prepared by melt mixing in a Brabender Plasti-Corder. As the torque ratio of RTPP and ABS was about 2, phase cocontinuity in the blends was achieved at ABS volume fractions around 0.16, which was evidenced by both microscopic analysis and mechanical testing. A new microscopic and image analysis technique was introduced, whose combination provides two semiquantitative parameters: structure roughness and structure cocontinuity. The latter parameter is closely associated with the predictive scheme based on the equivalent box model and percolation theory, which was used in this study. The predicted mechanical properties were confronted with the experimental data for tensile modulus, yield strength, and tensile impact strength. While the modulus of noncompatibilized blends is reasonably fitted by the model, the compatibilizer accounts for a positive deviation attributed to a strong interaction between the compatibilizer and the matrix. The yield strength of noncompatibilized blends indicates poor interfacial adhesion, which is so enhanced by the compatibilizer that no phase debonding occurs before yielding. Tensile impact strength, in contrast to modulus and yield strength, passes through a deep minimum for both types of blends; two tentative explanations of this detrimental behavior were suggested. POLYM. ENG. SCI., 47:582-592, 2007. [c] 2007 Society of Plastics Engineers, INTRODUCTION Preparation of polymer blends is known as a cost-effective way of upgrading various mass-scale polymers. As can be seen in available literature [1-8], polyolefin blends with styrenics still attract [...]

Fluorescence quenching of phenanthrene (Ph) and anthracene (An) fluorophores by maleic anhydride (MAH) and n-octadecenylsuccinic anhydride (ODSA) quenchers in solid polypropylene (PP) films were studied. Results were compared with fluorescence quenching of the same fluorophores by MAH and ODSA quenchers in chloroform solution. Contrary to the results obtained in solution, it was observed that fluorescence emission of Ph fluorophore in PP films was more efficiently quenched by ODSA than by MAH. This was due to the better miscibility of Ph with ODSA than with MAH. When An fluorophore was used instead of Ph, it was observed that its fluorescence intensity in PP films was notably reduced by the addition of MAH. This was mainly due to the Diels--Alder reaction, which consumed a part of the An molecule. However, fluorescence intensity of An strangely increased with the addition of ODSA instead of MAH. Because of short lifetime of An (around 6 ns), ODSA had no quenching effect on An. POLYM. ENG. SCI., 47:192-199, 2007. © 2007 Society of Plastics Engineers, INTRODUCTION Fluorescence quenching of polyaromatic molecules by electron deficient molecules was extensively studied in liquid solutions and both dynamic (collisional) and static fluorescence quenching mechanisms were developed [1-3]. The collisional [...]

The effect of the volume fraction of a dispersed phase on improvement in the toughness of injection-molded isotactic polypropylene (i-PP), blended with a styrenic thermoplastic elastomer, has been studied. The volume fraction of the dispersed phase, which indicates compatibility between elastomer and i-PP, depends on the molecular structure of a soft segment and the copolymerization ratio of styrene. The volume fraction of the dispersed phase of the i-PP blended with styrene-ethylene-propylene-styrene tri-block copolymer (SEPS) was higher than that of the i-PP blended with styrene-ethylene-butylene-styrene tri-block copolymer (SEBS). The volume fraction of the dispersed phase increases as the copolymerization ratio of styrene increases. Improvement in the toughness of the blended i-PP clearly depends on relaxation of strain constraint by void formation from the dispersed phase. Its efficiency proved to be dependent on the strength and the volume fraction of the dispersed phase depending on the compatibility between elastomer and i-PP. POLYM. ENG. SCI., 45: 1630-1638, 2005. [c] 2005 Society of Plastics Engineers, INTRODUCTION Frequent studies have been made on the toughness improvement in isotactic polypropylene (i-PP), for example, by melt-mixing the polymer with suitable elastomers [1-3]. The study results suggest that the [...]

Montmorillonite is a promising substitute for aluminum trihydroxide in flame-retardant polypropylene/aluminum trihydroxide (PP/ATH) composites. Study was made of the partial substitution of organoclay for ATH in PP/ATH composites. The total concentration of filler was kept at 30 wt%. The composites were compatibilized with two types of compatibilizer: commercial maleic anhydride functionalized polypropylene (PP-g-MA) and hydroxyl-functionalized polypropylene (PP-co-OH) prepared with metallocene catalyst. The effect of compatibilization on the morphology was studied by the transmission electron microscopy and the scanning electron microscopy. Mechanical properties were characterized by tensile and impact measurements, and flammability properties with a cone calorimeter. Addition of compatibilizer and stearic acid (SA) treatment of the ATH particles contributed to the dispersion of the fillers. Both compatibilizers produced organoclay with exfoliated structure and improved adhesion between the fillers and the matrix. Toughness improved and decomposition and flammability were reduced. POLYM. ENG. SCI., 45:1568-1575, 2005. [c] 2005 Society of Plastics Engineers, INTRODUCTION Flame retardancy is commonly introduced to polymers by adding metal hydroxide filler, such as aluminum trihydroxide (ATH). Typically about 60 wt% of filler is required, however, and this creates [...]

The effects of processing conditions on appearance characteristics of injection-molded mineral-filled polypropylene (compounded with pigments giving differing intensities of a beige color) have been studied; characteristics studied included gloss, color, and texture. A mold cavity embossed with smooth, fine, and coarse surface patterns was used. In-mold rheology and gate-seal analysis were used to select the filling and postfilling processing parameters. Interest was focused on the effects of filling rate, holding pressure, and mold temperature on the appearance characteristics, and a significant influence of these processing conditions on the gloss and color was found. For all the surface patterns examined, a better replication of the mold texture was obtained with a low melt viscosity at a high shear rate (high injection speed or short injection time) and a high mold temperature. This gave a higher gloss in the smooth surface regions and a lower gloss in the textured regions. An increase in the holding pressure had an effect similar to but smaller than increasing the filling rate or mold temperature. The gloss (or surface topography) had a significant effect on the color; an increase in gloss was associated with an increase in the color coordinate b* and a decrease in the lightness L*. POLYM. ENG. SCI., 45:1557-1567, 2005. © 2005 Society of Plastics Engineers, INTRODUCTION A satisfactory visual impression of the end product is one of the basic quality criteria for polymer injection molding. The assessment of surface appearance is increasingly important, including not [...]

This research explores the interlayer effect, dynamic mechanical properties, hysteresis behavior, and dynamic antivibration properties of PEL (polypropylene oxide-polyethylene oxide copolymer with LiCI[O.sub.4] 20 wt%) for modified PU (mPU) blends with clay and organoclay of varying amounts. The results show that the d-spacing between the layers of clay and organoclay ranges between 1.78-1.88 nm in the presence of PEL. The dynamic mechanical analysis indicates that the presence of clay and organoclay increases the vibration isolators of the nanocomposites under 20°C. It is found that organically modified clay significantly improves the antivibration performance of the blends based on the compressive vibration hysteresis effect. From the results of the dynamic antivibration test, the dynamic ratio of the blends decreases with the addition of clay or organoclay. In addition, clay is better than organoclay in enhancing the vibration isolation of the mPU blends. POLYM. ENG. SCI., 45:539-548, 2005. © 2005 Society of Plastics Engineers, INTRODUCTION Polymers exhibit uniquely high damping behavior in their glass transition zone due to conversion of mechanical vibration into heat energy through friction between molecular chains and heat dissipation [1]. [...]