**5. Novel polyurethanes based on aminolysis product of PET waste**

The product obtained, BHETA has potential for further reactions to synthesize useful products. Using ethanolamine to obtain BHETA and BHETA-based polyurethanes has been investigated in author's works. Three types of polyurethanes have been synthesized using BHETA. In the first case, BHETA is used as ring opening agent in caprolactone polymerization, and then novel biodegradable polyurethane has been synthesized. In the second and third cases, BHTEA is used as chain extender to synthesis of high modulus and special polyurethanes which is discussed in the next topics.

#### **5.1 First step: Aminolysis of PET waste to obtain BHETA**

In aminolysis with ethanolamine, the obtained product, BHETA is in its pure. Mechanism of synthesis of BHETA which proposed by Shukla and Harad is shown in Fig. 14. ( Shukla SR, et al (2006). Ethanolamine was used for the aminolysis of PET waste materials in the molar ratio 1:6 (PET: ethanolamine) under reflux in the presence of catalyst for time period up to 5 h. The catalyst, sodium acetate, was used in concentration 1% by weight of polymer. At the end of the reaction, distilled water was added in excess to the reaction mixture with vigorous agitation to precipitate out the product, BHETA.

The filtrate contained mainly unreacted ethanolamine and little quantities of a few water soluble PET degradation products. The precipitate obtained was filtered and dissolved in distilled water by boiling for about 20 min. White crystalline powder of BHETA was obtained by first concentrating the filtrate by boiling and then chilling it. It was further purified by recrystallisation in water. It was then dried in an oven at 80°C. Different techniques of analysis were used for characterization of BHETA.

After synthesis and high purification, BHETA has been characterized using 1HNMR and Fourier transform infrared (FTIR) spectroscopy depicted in Figures 15-16. BHETA has been shown in Fig. 15, it may be clearly seen that the spectrograph contains peaks at 1056 and 3288 Cm-1 indicating the presence of primary alcohol. The peaks for secondary amide stretching are observed at 1311, 1554 and 3369 Cm-1. Fig. 16 shows the 1H NMR spectra of

which they are reacted in polyurethanes. Therefore, polyurethanes have received recent attention with regard to the development of degradable polymers because of their great potential in tailoring polymer structures to achieve mechanical properties and biodegradability to suit variety of applications such as biodegradable polymers, soft tissue adhesives, clinical demand and meniscus scaffold. Multiblock copolymers based on caprolactone and lactic acid, polyglycoles, polyesters and multifunctional aliphatic carboxylic acids as soft segments have been investigated used in various applications such as medical or industrial fields. Commercial polycaprolactones with different molecular weights as a soft segment, Polycaprolactone-based polyurethanes using diols such as Ethyleneglycole BHET, 1,4-butanediol or other diols as chain extender for ring opening polymerization of caprolactone have been studied. Using of nature-based polyols to prepare polyurethane foams is common but there are few reports on elastomeric polyurethane. Presence of aromatic ring in PET structure caused to improve mechanical and thermal properties of polyurethane structure; while presence of esteric bonds leads to

biodegradation. (Yeganeh et al, 2007; Heijka R et al, 2005)

special polyurethanes which is discussed in the next topics.

**5.1 First step: Aminolysis of PET waste to obtain BHETA** 

vigorous agitation to precipitate out the product, BHETA.

techniques of analysis were used for characterization of BHETA.

**5. Novel polyurethanes based on aminolysis product of PET waste** 

The product obtained, BHETA has potential for further reactions to synthesize useful products. Using ethanolamine to obtain BHETA and BHETA-based polyurethanes has been investigated in author's works. Three types of polyurethanes have been synthesized using BHETA. In the first case, BHETA is used as ring opening agent in caprolactone polymerization, and then novel biodegradable polyurethane has been synthesized. In the second and third cases, BHTEA is used as chain extender to synthesis of high modulus and

In aminolysis with ethanolamine, the obtained product, BHETA is in its pure. Mechanism of synthesis of BHETA which proposed by Shukla and Harad is shown in Fig. 14. ( Shukla SR, et al (2006). Ethanolamine was used for the aminolysis of PET waste materials in the molar ratio 1:6 (PET: ethanolamine) under reflux in the presence of catalyst for time period up to 5 h. The catalyst, sodium acetate, was used in concentration 1% by weight of polymer. At the end of the reaction, distilled water was added in excess to the reaction mixture with

The filtrate contained mainly unreacted ethanolamine and little quantities of a few water soluble PET degradation products. The precipitate obtained was filtered and dissolved in distilled water by boiling for about 20 min. White crystalline powder of BHETA was obtained by first concentrating the filtrate by boiling and then chilling it. It was further purified by recrystallisation in water. It was then dried in an oven at 80°C. Different

After synthesis and high purification, BHETA has been characterized using 1HNMR and Fourier transform infrared (FTIR) spectroscopy depicted in Figures 15-16. BHETA has been shown in Fig. 15, it may be clearly seen that the spectrograph contains peaks at 1056 and 3288 Cm-1 indicating the presence of primary alcohol. The peaks for secondary amide stretching are observed at 1311, 1554 and 3369 Cm-1. Fig. 16 shows the 1H NMR spectra of chain extender. The purified BHETA was characterized by FTIR, 1HNMR, and melting point. Synthesized BHETA has been melted at 227°C.

Fig. 14. Depolymerization mechanism of (2-hydroxy ethylene) Terephthalamide.

The FTIR spectrograph of the purified As can be seen, the shift and splitting pattern of 1H NMR at 8.52 ppm, 7.91ppm , 4.73 ppm, 3.52 ppm and 3.34 ppm, corresponding to H of the amine group, aromatic ring, hydroxyl Group, CH2 bonded to hydroxyl group, and CH2 bonded to amine group respectively. These obtained results confirmed that the PET fibers depolymerized and expected product (BHETA) was synthesized successfully.

Fig. 15. 1HNMR spectrum of BHETA.

From PET Waste to Novel Polyurethanes 371

Fig. 17. Ring opening polymerization of caprolactone by BHETA to obtain polyol.

Table 1. Molar ratios, theoretical and experimental "Mn" and "n" of used polyols.

Fig. 16. FTIR spectrum of BHETA.
