**5.1. Experimental**

*Example 1 of glycolysis reaction:* Small pieces of PET waste (100 g), equivalent to 0.5 mol repeating unit (mol.wt. 192 gmol-1) were added to 88.64 g PG (mol.wt. 76.09 gmol-1), 173.07 g TEG (mol.wt.150 gmol-1) or 461.5 g PEG 400 (mol.wt. 400 gmol-1), such that the molar ratio of PET repeating unit to glycol was 1:2.

*Example 2 of glycolysis reaction:* In the second experimental runs of depolymerisation, appropriate amount of PET waste were added to 396.1 g PG, 750 g TEG or 2173 g PEG 400, so that molar ratio of PET repeating unit to glycol was 1:10. These mixtures (with different molar ratio PET/glycol) and 0.5 wt.% zinc acetate (based on the weight of PET as transesterification catalyst) were charged to a glass reactor, which was fitted with stirrer, reflux condenser, nitrogen inlet and temperature controller. This reactor was immersed in an oil bath and the content of the reaction kettle was heated at 190 oC for 2 h, subsequently the temperature was raised to 210 oC until all the solids disappeared.

90 Polyurethane

thermal resistance of the chains.

the products formed.

**5.1. Experimental** 

dimine (EDA) as chain extender.

PET repeating unit to glycol was 1:2.

**recycled poly (ethylene terephthalate)** 

second group can be observed in the range, varying maximum of the peak, from 267 to 347 oC, for PPG soft segments. A marked difference can be observed, promoted by changing the type of chain extender in DTG profiles, especially in the first stage of weight loss, corresponding just to urethane (EG or PG as chain extender) linkage degradation. The soft segment, formed only by PPG degradation step seemed to be also affected. The rigid segment formed from EG retarded the weight loss of PPG chains (peak at 375 oC), while PG showing peaks at 267 oC (Cakić et al., 2006, 2007 c). All DTG curves showed that there are different stages of degradation which are not perceptible in TG curves, showing the close

The degradation profiles of PU cast films obtained from water-based dispersions were influenced by the type of chain extender, length of the hard segment and type of catalysts. The presence of more selective catalysts, which formed urethane linkages with higher hard segment proportions, had a marked influence on the degradation of the polymers, especially in elevated quantities, improving the thermal stability of the materials. The DTG curves showed that the length of the hard segment had a strong influence on the thermal profile of the samples as a whole. The type of chain extender, forming urethane linkages, affected the whole process of degradation and the presence of more selective catalyst improved the

relation and mutual influence between degradation of hard and soft segments.

**5. Water-based PUD based on glycolized products obtained from** 

production of plastics or other advanced meterials (Patel et al., 2007).

Recycling of polymers has received a great deal of attention (Atta et al., 2006, 2007). Although several methods have been proposed for recycling waste poly(ethylene terephthalate) (PET), it is suggested that the most attractive method is glycolysis of chemicals into the corresponding monomers or raw chemicals that could be reused for the

Two-stage PUD synthesis was applied: the first, glycolysis of PET using different types of glycols (PG), triethylene glycol(TEG) and poly(ethylene glycol) (PEG 400), with different molar ratio of PET repeating unit to glycol (1:2 and 1:10); the second, preparation of PUD of

PUD are prepared by anionic dispersion process (Cakić et al., 2011), using IPDI, glycolyzed products, DMPA as potential ionic center which allow water dispersibility and ethylene

*Example 1 of glycolysis reaction:* Small pieces of PET waste (100 g), equivalent to 0.5 mol repeating unit (mol.wt. 192 gmol-1) were added to 88.64 g PG (mol.wt. 76.09 gmol-1), 173.07 g TEG (mol.wt.150 gmol-1) or 461.5 g PEG 400 (mol.wt. 400 gmol-1), such that the molar ratio of The obtained glycolyzed oligoester polyols were analysed by the hydroxyl value (HV) determination according to the conventional acetic anhydride/pyridine method (Cakić et al., 2011). The hydroxyl value of the oligoester polyol obtained in the glycolysis reaction based on molar ratio of PET repeating unit to glycol, 1:2, with PG was HBPG=490 mg KOH/g, TEG HBTEG=370 mg KOH/g and PEG HBPEG400=297 mg KOH/g.

The hydroxyl value of the oligoester polyol obtained in the glycolysis reaction based on molar ratio of PET repeating unit to glycol, 1:10, with PG was HBPG=201 mg KOH/g, TEG HBTEG=209 mg KOH/g and PEG HBPEG400=192 mg KOH/g.
