Comparative techniques for molecular weight evaluation of poly (ethylene terephthalate) (PET)

Kinetics of catalytic glycolysis of PET wastes with sodium carbonate

“…Samples having a particle size of about 3 mm were first conditioned with an aqueous diluted (1 %wt) sodium hydroxide (Panreac) solution for about 1 h to remove any surface impurities and subsequently washed with water and dried in an oven at 80 • C. The intrinsic viscosity of PET, measured in a 60/40 (w/w) phenol (Panreac)/1,1,2,2-tetrachloroethane (Fluka) solution at 30 • C using the Billmeyer relationship (ASTM 4603), was 0.73 dL g −1 . On the basis of the Mark-Houwink method both number-average molecular weight (3.3 × 10 4 g mol −1 ) and weightaverage molecular weight (5.0 × 10 4 g mol −1 ) were calculated from this intrinsic viscosity value [47]. PET scraps were cut with a cryogenic rotary cutter (Retsch ZM 2000) in order to obtain various fractions with a particle size between 0.14 and 1.67 mm.…”

Preparation of PET/clay nanocomposites via in situ polymerization in the presence of monomer‐activated organoclay

“…Based on Billmeyer and Mark-Houwink equations [16], intrinsic viscosity and the number average molecular weight (M n ) of all samples were calculated, respectively. The Billmeyer equation is…”

“…As can be noticed, with increasing either the Cloisite 30B or the RM-Cloisite 30B content in the PET matrix, the position of the exothermic peaks is gradually shifted, whereas the peaks become moderately narrower and sharper. The DT c values of PETCNs are in the range of [14][15][16][17][18] C, which are narrower than that for pure PET (about 26 C), indicating that the added nanoclay particles act as effective heterogeneous nucleating agents that significantly enhance the crystalline structures as their loading is increased. It is also suggested that nanoclay itself can help the PET molecules stack on each other in order to grow into crystallites, thus leading to the higher crystallization rate [24].…”

Chain extension of poly (ethylene terephthalate) by reactive extrusion with secondary stabilizer

“…After ground previously, PET samples (0,1 g) were dissolved in the solvent mixture (20 mL) at 110 °C for 5 hours After the complete solubilization, the solutions were filtered and tested at 30 °C in water bath, according to standard test method ASTM D 4603 21 . From the flow time of the pure solvent mixture (t 0 ) and of PET solutions (t), it was possible to obtain the relative (ηr), specific (η esp ), reduced (η red ) and inherent (η iner ) viscosities by means of the following equations 22,23 :…”

“…The extrapolation of η red or η iner to concentration limit tending to zero gives intrinsic viscosity ([η]) 22,23 :…”