To produce high-performance poly(ethylene terephthalate) (PET) composites f
rom the polymerization of ethylene terephthalate cyclic oligomers (ETCs) pr
epared From PET waste, the viscosity, thermal stability, and crystallizatio
n of ETC melts were investigated, and ETC melt was; polymerized with cyclic
dibutyltin initiator (cyclic stannoxane 1). The melt viscosity of ETCs at
295 degrees C where all ETCs can be melted was about 30 cP initially. The v
iscosity of the completely molten ETCs remained sufficiently constant at 29
5 degrees C to allow time for infusion into large composite preforms. and n
early all of the ETC molten sample remains a liquid for tens of seconds whe
n quenched to the most desirable polymerization/solidification temperature.
From the polymerization and crystallization results, it was found that the
optimum polymerization temperature is approximately 230 degrees C. PET pol
ymerized at this temperature had enough crystallinity for a good composite
matrix; however, the molecular weights of such PETs were too low to form su
fficiently strong tough matrices for composites; this is probably due to sm
all amounts of impurities which produce low molecular weight PET and inadeq
uate thermal stability of the cyclic stannoxane 1 initiator at this tempera
ture.