Properties of polymerized cyclic butylene terephthalate and its composites via ring-opening polymerization:

Continuous glass fiber (GF)-reinforced polymerized cyclic butylene terephthalate (pCBT) composites were prepared via vacuum-assisted resin transfer molding using butyltin tris(2-ethylhexanoate) as the catalyst. The relationship between melt viscosity and polymerization time was examined in the ring-opening polymerization of CBT resin. The effects of polymerization conditions such as catalyst content and polymerization temperature on viscosity average molar mass (M-v ), crystallization, mechanical properties, and microstructure of GF/pCBT composites were also investigated in detail. It is found that both high molecular weight and high degree of crystallinity of resin matrix can lead to high mechanical properties of composites. The composites prepared with 0.5% catalyst at 190 degrees C show the best mechanical properties with tensile strength of 549 MPa, flexural strength of 585.2 MPa, and interlaminar shear strength of 47.1 MPa. The scanning electron microscopy analysis also demonstrates that good interfacial adhesion exists between fiber and resin, which agrees very well with experimental results.