摘要:
Processes for producing polyethylene terephthalate copolyesters are disclosed, that include the steps of: esterifying a mixture of at least terephthalic acid, from 20 mole percent to 45 mole percent 1,4-cyclohexanedimethanol, and ethylene glycol, optionally in the presence of one or more alkaline earth metals or alkali metals, to form an oligomer; polycondensing the oligomer in the melt phase in the presence of aluminum and one or more alkaline earth metals or alkali metals, to obtain a copolyester having an intrinsic viscosity of at least 0.5 dL/g; and thereafter adding to the copolyester a phosphorus-containing compound.
摘要:
A method for providing a standard Raman spectrum from a sample uses a particular Raman spectrometry apparatus or any similar Raman spectrometry apparatus, which is used to simultaneously irradiate a reference material and at least one sample, thereby obtaining their respective convolved Raman spectra. Using a defined standard energy dispersion characteristic and a standard Raman spectrum of the reference material, a convolution function is determined and applied to produce a deconvolved Raman spectrum of the sample. This deconvolved spectrum is multiplied by a defined standard photometric response function to produce a standard Raman spectrum of the sample. A method for providing an accurate and precise quantitative analysis of the chemical composition and/or physical properties of an unknown sample uses the standard Raman spectra of a plurality of known samples to construct a normalized calibration, which is applied to a standard Raman spectrum of the unknown sample to produce an accurate and precise quantitative analysis thereof, using any similar Raman spectrometry apparatus.