SynopsisComposites of polypropylene-CaC03 coated with isopropoxy triisostearoyl titanate have been prepared on Buss KO-Kneader. These composites have been evaluated for mechanical properties, melt index, dispersion, and adhesion of polymer to filler using the scanning electron microscope. Calcium carbonate being a platelike substance with low aspect ratio results in com~osites having inferior tensile properties but superior impact characteristics. Uniform dispersion of filler in the composite and long alkyl chains of the coupling agent provide additional advantages such as improved melt index, higher tensile elongation, and better optical properties.
The occurrence of transcrystallinity in polypropylene in the presence of mica flakes was studied. Both uncoated mica as well as mica coated with triisostearoylisopropyl titanate (TTS) developed transcrystallinity. Injection molded samples of polypropylene filled with uncoated mica and also mica coated with TTS were prepared separately. The fracture surface analysis under scanning electron microscope revealed that the interfacial bondage between the polymer and mica was poor. This study clearly indicates that transcrystallinity does not influence the interfacial bondage.
ZUSAMMENFASSUNG:Das Auftreten von Transkristallisationsvorgangen in Polypropylen in Gegenwart von Glimmerschuppen wurde verfolgt. Sowohl unbeschichteter als auch mit Triisostearylisopropyltitanat (TTS) beschichteter Glimmer bewirkten eine Transkristallisation. Spritzgegossene Proben von mit unbeschichtetem und mit TTS-beschichteten Glimmer gefiilltem Polypropylen wurden getrennt hergestellt. Die Bruchflachenanalyse im Rasterelektronenmikroskop zeigte, da8 die Grenzflachenbindungen zwischen dem Polymeren und Glimmer schwach waren. Diese Arbeit zeigt klar, dal3 Transkristallisation die Grenzflachenbindung nicht beeinflufit.
Polypropylene composite samples with concentrations of mica of 10,20, 30, 40, 45, 50, and 60 wt percent were prepared under identical conditions by injection molding. The influence of mica concentration on the structure and mechanical properties of the composites was investigated using a polarizing microscope, scanning electron microscope, differential scanning calorimetry, and stress-strain characteristics. Flexural and impact strengths show a n initial rise and then gradual fall with increasing mica concentration. An optimum of these properties occurred at -20 wt percent mica. Tensile modulus and heat distortion temperature show a continuous rise: whereas the percent elongation decreased with mica content. These changes in properties are discussed in terms of a skin-core morphology, transcrystallinity, crystallinity, fracture surface morphology, flake orientation, and interfacial adhesion in these composites. This study helps in optimizing the mica concentration for injection molded composites.
This paper discusses about the development and nature of property relationships generated by blending a low cost homopolymer (PVC) with ABS terpolymer. The blend properties are strongly influenced by the phase behaviour of the constituents which is due to interactions among them. PVC/ABS blends are microheterogeneous: they have a rigid matrix with soft dispersed phase but are mechanically compatible. Because of this partial compatibility, additive responses are observed (as a function of blend ratio) in tensile strength and modulus, flexural strength and modulus and viscosities. The mutual interaction also accounts for positive deviations of experimental specific gravities from empirically calculated ones, using the values for PVC & ABS alone. The pay-off for blending comes from "synergistic" improvements in the impact strength of PVC/ABS blends, which undoubtedly comes from the presence of discrete elastomeric phase. PVC/ABS blends are attractive not only due to their high impact but offer "built-in" flame retardance, moderate cost, good processability, high gloss etc.
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