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1 Journal of Achievements in Materials and Manufacturing Engineering

1 2012

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Mechanical and physical properties investigation of polyurethane material obtained from renewable natural source

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Santos dos D. J. , Tavares L. B. , Batalha G. F.

tom Vol. 54, nr 2

211--217

Purpose: The purpose of this paper is to investigate the influence of different polyol/diisocyanate ratios on the mechanical and physical behaviours of polyurethane based polymers. Design/methodology/approach: Castor oil was mixed, as polyol, to diisocyanate in order to obtain polyurethane based polymers. Besides the ideal stoichiometry, polyol/ diisiocyanate ratio, ratios with excess/ lack of diisocyanates were provided. The mechanical behaviour was investigated by uniaxial tests. Differential Scanning Calorimetry (DSC) and Thermo gravimetric Analysis (TGA) were used to investigate the thermal behaviour. The various polymeric structures, obtained by the different ratios, were analysed and compared by Infrared Spectroscopy (IR). Findings: Mechanical performance was increased proportionally to contend of diisocyanate. High levels of diisocyanate have generated elongation decreasing and CO2 formation during curing, damaging mechanical behaviour due to bubble presence. Analytical experiments have showed important changes on: polymeric structures, glass transition temperatures and behaviour at elevated temperatures. Research limitations/implications: Free acid and water contend were not taken into consideration by defining the ideal stoichiometry. The investigated formulations cannot be direct applied on practical applications; fillers and additives must be added to them, which were not taken in consideration. Practical implications: The obtained results can support development of adhesives, engineering polymers and polymeric matrix for structural composites. Stabling the relation between component ratios to their behaviours is possible to define optimal performance ranges and to avoid excess of diisocyanate on polymers. Originality/value: Deep investigation of PU based material, obtained from renewable natural source (castor oil). The results can orientate development of materials for industrial applications and researches using other oils as polyol.