Abstract
Previously we reported a new type of thermosetting resins, cross-linked polyesteramides, formed by the reaction of bis-2-oxazolines with dicarboxylic acids in the presence of an organic phosphite as catalyst. Since then, structure and properties of the resins have been studied. The materials used for making the resins are 2, 2′- (1, 3-phenylene) bis-2-oxazoline (1, 3-PBO), five kinds of aliphatic dicarboxylic acids-glutaric, adipic, azelaic, sebacic and dodecanedioic acids-and triphenyl phosphite.
The mole ratio of 1, 3-PBO to the dicarboxylic acid is required to be more than a unit for the formation of crosslinked resins. Complete curing needs 0.4% or more triphenyl phosphite as catalyst and heating the reaction mixture for 30 minutes at 180°C or for 10 minutes at 200°C. Water in the resin materials hinders curing.
Structure of the resins was proposed based on a model reaction and chemical analysis of a cured resin (Fig. 5).
Table 1 shows the properties of typical grades of the resins; the resins are very hard and strong. Some grades have the highest mechanical strengths and moduli and higher lzod impact strengths (7-10 kgf.cm/cm) than any other thermosetting resin. Relationship between the properties and composition of the resins is shown in Figures 6, 7, 8 and 9.
(Study on the thermosetting resins made from bis-2-oxazolines and acidic organic compounds (1))
