Polyurethanes (PUs) represent one of the most important groups of plastics, and so the increasing quantity of wastes makes their recycling an urgent task. The general purpose of PU chemical recycling is to recover constituent polyol, a valuable raw material. Among the suitable processes, glycolysis in two phases allows better quality products. The objective of this work is the evaluation of the option to apply the recovered polyols to obtain PU with identical characteristics to the starting raw material, and so several foaming tests were carried out according to the evaluation method employed in free expansion foaming of conventional flexible slabstock foams. To achieve this objective, a formulation recipe for flexible foams was selected, in which the raw polyol was totally or partially replaced for recovered polyol. The foaming formulations were modified because of the different amount of active hydrogens in the recovered polyols and the virgin polyol. Amounts up to 50% could be applied without relevant changes in rising profiles and the physical properties of the foams. The foams were characterized, and according to its appropriate characteristics they can be employed in the same applications where a commercial one made with raw polyol is used.
The quality of object oriented information systems (OOIS) depends greatly on the decisions taken at early phases of their development. As an early available artifact the quality of the class diagram is crucial to the success of system development. Class diagrams lay the foundation for all later design work. So, their quality heavily affects the product that will be ultimately implemented. Even though the appearance of the Unified Modeling Language (UML) as a standard of modelling OOIS has contributed greatly towards building quality OOIS, it is not enough. Early availability of metrics is a key factor in the successful management of OOIS development. The aim of this paper is to present a set of metrics for measuring the structural complexity of UML class diagrams and to use them for predicting their maintainability that will heavily be correlated with OOIS maintainability.
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