Hans Bertilsson

Recycling of ABS and ABS/PC blends†

The aim of this work within the framework of mechanical recycling of polymers is upgrading recycled engineering plastics by means of a blending technique. Four different plastics from dismantled Volvo cars have been investigated. They are poly(acrylonitrile-butadiene-styrene) (ABS) and ABS-polycarbonate (ABS/PC) as major components and poly(methyl methacrylate) (PMMA) and polyamide (PA) as minor components. Blending recycled ABS and PC/ABS (70/30) with a small amount of methyl methacrylate-butadiene-styrene core-shell impact modifiers gives the mixture better impact properties than any of its individual components. Some 10% of PMMA from tail light housings can follow the PC/ABS blends made. The property profile will rather be improved. However, PA is an incompatible component that should be sorted out from the mixture. Antioxidants and metal deactivators do not help the recyclates show better mechanical properties. Two toughness measurements, Charpy impact strength and J-integral method, show complimentary results for such blends.

Morphological changes probed as rheokinetics of whisker- and unfilled polymer blends

Abstract The rheological time dependencies of both whisker-filled (composites) and unfilled PE/PIB and SAN/PA6 blends were studied as functions of composition and shear history. A three-step experiment of steady dynamic—steady shear was designed. Rupture and formation of the morphology in batch-compounded blends/composites was conveniently and accurately studied in the first steady shear. The second step emphasises morphological sensitivity in blends close to phase inversion. During the oscillation phase metamorphosis and whisker transport were noticed. The third step together with microscopy studies confirmed these observations.

Morphological effects in SAN-PA6 blends induced by aluminum borate whiskers

The effects of aluminum borate whiskers on melt mixed poly(styrene-co-acrylonitrile)/polyamide 6 (SAN-PA6) blends have been investigated. With SAN as the major component, scanning electron microscopy reveals that PA6 creates a continuous phase with the whiskers, i.e a co-continuous morphology is created. For the inverse system, with PA6 as the major component, this effect does not occur. The interactions between PA6-whiskers and SAN-whiskers have been quantified as Lewis acid-base properties using inverse gas chromatography (IGC) at infinite dilution. Interactions between whiskers in PA6 are much stronger than between whiskers in SAN. The morphology of blends with SAN as the majority component is not stable at high shear rates. This can be explained by the rheological characteristics of the components, i.e. a crossover point in viscosity as a function of shear rate.

Effect of impregnation on mechanosorption in wood and paper studied by dynamic mechanical analysis

The results of dynamic mechanical measurements in dual cantilever and uniaxial tension of untreated Scots pine veneer and unbleached sulphate paper under stepwise changes in the relative humidity of the surrounding atmosphere between 5% and 85% are compared to corresponding results for acetylated samples and samples treated by impregnation with poly(ethylene oxide) (PEO), glycerol or melamine formaldehyde resin. The treatments resulted in significant reductions in the transient mechanical losses associated with stepwise humidity changes. Although acetylation of wood and impregnation with PEO or glycerol both result in greatly improved dimensional stability with respect to humidity changes, the two types of treatment appear to be fundamentally different in terms of the models used here to interpret the results.We find that it is helpful to consider the dynamic process of moisture sorption/ desorption in these samples in terms of two coupled processes: the diffusion of moisture into or out of the sample, with a characteristic diffusion time given approximately by t* = π/16)h2/D where h is the sample thickness and D a characteristic diffusion constant for the moisture in the material, and the attachment/detachment of (clusters of) water molecules to binding sites in the samples, apparently with characteristic “chemical” relaxation times of the order of seconds or minutes. Clearly, when the sample thickness is quite small, 0.8 mm in our case, and the diffusion coefficient of the order of 50 × 10−8 cm2/s, then the characteristic diffusion time is about 40 minutes, already for these small dimensions more than an order of magnitude larger than the characteristic “chemical” relaxation time. By varying the frequency of the dynamic mechanical measurements these characteristic processes for untreated and treated samples can be probed in some detail.

Enhanced conductivity in conducting polymer blends induced by aluminum borate whiskers

The influence of a filler on melt-mixed conducting polymer blends of poly(3-octylthiophene) (POT) has been examined with respect to their morphology, rheology, conductivity and acid-base properties. The matrix polymers used were low density polyethylene (LDPE), poly(vinyl chloride) (PVC) and poly(methyl methacrylate) (PMMA) and the filler was non-conducting aluminum borate whiskers. These blends show two-phase behavior when examined by scanning electron microscopy. It was found that the adhesion at the polymer-filler interface in combination with the viscosity ratios between the polymers exerts a considerable influence on the morphology and hence on the conductivity. For the PE/POT blends, addition of whiskers changed the morphology and increased the conductivity by several orders of magnitude. The conductivity of blends with PVC was almost unchanged while the conductivity of PMMA blends slightly decreased upon addition of whiskers. The interactions between whiskers and the polymers used decreased in the ...

Damping Properties of a Mica-Filled Latex IPN Structure and Applications in Constrained-Layer Damping

The influence of platelet mica fillers on the damping properties of a polymer specimen produced from a coreshell latex based on styrene, methyl methacrylate and ethylhexylacrylate was evaluated. This polymer is expected to exhibit an interpenetrating network (IPN) structure, and in the unfilled state it exhibits a rather broad glass transition (Tg) region. The damping peak (tan δ), evaluated by dynamic mechanical analysis (DMA), became somewhat higher when mica filler was added to the polymer but the Tg-region became somewhat narrower. The filler particle size had no appreciable influence on the damping properties of the filled polymer. Silane treatment of the mica resulted in a slight broadening of the glass transition (lower temperature side of the peak) and a decrease in the magnitude of the damping peak compared to the result obtained with untreated mica of the same particle size. The results of the DMA measurements on the polymer samples were used to calculate the composite loss factor (CLF) for a steel laminate consisting of two steel plates with a thin intermediate polymeric layer, using the theory proposed by Ross, Ungar and Kerwin (RUK). The calculated results were compared with the measured composite loss factors at higher frequencies (200 Hz or more) determined in vibrating beam tests (VBT). The agreement between the calculated and measured values with regard to the temperature location of the damping peak was reasonably good for the unfilled material, provided that the DMA values used * To whom correspondence should be addressed. for the calculations were recalculated using the timetemperature superposition principle to the actual higher frequencies used in the VBT. For the filled systems, the RUK theory predicted the location of the CLF-damping peak to be ca. 5°C higher than was observed experimentally. Possible reasons for this are discussed. Addition of the mica to the polymer affected the experimentally determined CLF values somewhat, but the changes were not very dramatic. K e y W o r d s : constrained-layer damping, core-shell latex, fillers, glass transition, LIPN, metal-polymermetal laminate