Synthesis, characterization, and cure of propargyl-functionalized cyclopentadiene for use in carbon-carbon composites

A new composite resin was synthesized by reaction of cyclopentadiene with p ropargyl bromide and base under phase transfer conditions to give a mixture of products with two to six propargyl functionalities per cyclopentadiene ring. DSC analysis of the propargylated cyclopentadiene resin (PCP) showed thermal cure with no added initiator over a broad temperature range with a peak at 250 degrees C. FT-IR analysis of the cured resin showed the generat ion of new unsaturated and saturated species through a hydrogen transfer en e-like reaction and polyaddition of the propargyl groups to give oligomers and/or cyclotrimers. X-ray analysis showed no long-range graphitic order, N eat PCP resin cured at 250 degrees C gave a room temperature flexural modul us of 2.9-3.0 GPa by DMA and showed no thermal transitions up to 300 degree s C while PCP/carbon fiber composites gave a room-temperature flexural modu lus of 115-120 GPa and a flexural strength of approximately 950 MPa, TGA sh owed exceptional carbon yield at 1000 degrees C with 75% weight retention i n both air and N-2, while composites with 40 wt % resin showed 90% carbon y ield. Interlaminar shear strengths of carbonized samples were comparable to those of presently used materials.