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2 2009

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Some effects of multiple injection moulding on selected properties of ABS

Żenkiewicz M., Rytlewski P., Moraczewski K., Stepczyńska M., Karasiewicz T., Malinowski R., Ostrowicki W.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 37, nr 2

361-368

Purpose: The purpose of this work was to investigate the influence of multiple (up to 10 times) injection moulding of acrylonitrile butadiene styrene (ABS) on some properties of the obtained moulded pieces. Design/methodology/approach: The investigated samples were obtained during the industrial injection moulding. There were determined the sample mechanical properties (by a tensile test), melt flow rate, temperatures of phase transitions (by differential scanning calorimetry, DSC), temperatures of thermal degradation (by thermogravimetric analysis, TGA), as well as storage modulus and damping coefficient (both by dynamic mechanical analysis, DMA). Findings: After the first injection mouldings, minor decreases (ca. 2.0 %) in the tensile strength were observed. After the next injection mouldings, this quantity did not change much. The melt flow rate increased along with the number of injection mouldings. The glass transition temperatures (from DSC) of butadiene and acrylonitrile styrene fractions don’t vary with the number of injection mouldings and are ca. 61 and +104şC, respectively. Research limitations/implications: In order to confirm that degradation process occurs in ABS during injection mouldings, further investigation is necessary, mostly that on variations in the mean molecular weight of ABS. Practical implications: The studies carried out by now indicate that there are no arguments not to subject the ABS technological waste to the management by material recycling. Originality/value: It has been observed that the largest changes in the tensile strength and melt flow rate of ABS occur during its first injection moulding and a melt flow rate increases slightly with the number of injection mouldings. The temperatures of phase transitions and thermal as well as the storage modulus and damping coefficient of ABS do not essentially change after repeated injection mouldings.

Effect of multiple injection moulding on some properties of polycarbonate

Żenkiewicz M., Rytlewski P., Moraczewski K., Stepczyńska M., Karasiewicz T., Richert J., Ostrowicki W.

Archives of Materials Science and Engineering

2009

Vol. 37, nr 2

94-101

Purpose: The aim of this work was to investigate the influence of multiple (up to 6 times) injection moulding of polycarbonate (PC) on some properties of the obtained moulded pieces. The investigation results are to be used to evaluate the usefulness of the multiple processing of PC and management of the PC technological waste by material recycling. Design/methodology/approach: The investigated samples were obtained during the industrial injection moulding. There were determined the sample mechanical properties (by a tensile test), melt flow rate, temperatures of phase transitions (by differential scanning calorimetry, DSC), temperatures of thermal degradation (by thermogravimetric analysis, TGA), as well as storage modulus and damping coefficient (both by dynamic mechanical analysis, DMA). Findings: After the first and second injection mouldings, minor increases (ca. 2.2 wt.% in sum) in the tensile strength of polycarbonate were observed. After the next injection mouldings, this quantity did not change much. The melt flow rate increased along with the number of injection mouldings. The glass temperature was approximately constant while the other phase transition temperatures decreased by ca. 7° C after the first injection moulding and they did not essentially change after each of the next five processing procedures. The storage modulus and damping coefficient of polycarbonate were not noticeably affected by the number of injection mouldings. Research limitations/implications: In order to confirm the claim that degradation processes, occurring in polycarbonate during the first two injection mouldings, cause an increase in the van der Waals interactions between the polymer macromolecules, further investigation is necessary, mostly that on variations in the mean molecular weight of polycarbonate. Practical implications: The studies carried out by now indicate that there are no arguments not to subject the polycarbonate technological waste to the management by material recycling. Originality/value: The method for calculating the fraction of multi-processed plastic in a final product is presented. It has been observed that the largest changes in the examined properties of polycarbonate occur during its first injection moulding. It is stated that a minor degradation of polycarbonate macromolecules increases slightly its tensile strength, caused probably by enhancement of the van der Waals forces.