Chemical Recycling, Kinetics, and Thermodynamics of Poly (Ethylene Terephthalate) (PET) Waste Powder by Nitric Acid Hydrolysis

Purpose Poly(ethylene terephthalate) (PET) waste from soft drink bottles was incorporated into palm olein alkyd to produce new polyol for use in polyurethane resins as surface protection on metal surfaces. Design/methodology/approach Alkyd was prepared from palm olein, glycerol and phthalic anhydride. PET underwent simultaneous glycolysis and transesterification reactions with the alkyd. Varying the amount of PET has led to polyols with different viscosities. Polyurethane resins were produced by reacting the polyols with toluene diisocyanate. The resins were coated on mild steel panels and cured. Performances of the cured films were tested. Findings The polyurethanes (PU) resin cured to a harder film with better thermal stability. Films showed excellent adhesion properties, while higher content of PET exhibited higher pencil hardness, better water, salt, acid and alkali resistance. Research limitations/implications Other vegetable oils could also be used. The alkyd structure could be changed by formulation to have different functionality and the ability to incorporate higher amount of PET waste. Rate of glycolysis of PET could be increased by higher amount of ethylene glycol. Practical implications This method has managed to use waste PET in producing new polyol and PU resins. The cured films exhibit good mechanical and chemical properties, as well as excellent adhesion and thermal stability. Social implications The non-biodegradable PET has created environmental pollution problems connected to littering and illegal landfilling. It has become necessary to pay greater attention to recycling PET bottles for obtaining valuable products. Originality/value This approach is different from the earlier reports, where PET was recycled to recover the raw materials.

Download Full-text

Synthesis and sizing performances of water-soluble polyester based on bis(2-hydroxyethyl) terephthalate derived from depolymerized waste poly(ethylene terephthalate) fabrics

Textile Research Journal ◽

10.1177/0040517517750652 ◽

2018 ◽

Vol 89 (4) ◽

pp. 572-579 ◽

Cited By ~ 2

Author(s):

Jing Lu ◽

Mengjuan Li ◽

Yanyan Li ◽

Xiaoqiang Li ◽

Qiang Gao ◽

...

Keyword(s):

Surface Tension ◽

Fourier Transform ◽

Ethylene Terephthalate ◽

Water Soluble ◽

Chemical Recycling ◽

Step Method ◽

Pet Fabric ◽

Poly Ethylene Terephthalate ◽

Poly Ethylene ◽

Viscosity Stability

This work aimed at effective chemical recycling of waste poly(ethylene terephthalate) (PET) fabrics into water-soluble polyester (WSP). For this, PET fabric waste was depolymerized using excess ethylene glycol (EG) in the presence of zinc acetate as catalyst. The glycolysis product of PET, bis(2-hydroxyethyl) terephthalate (BHET) was then used to synthesize WSP by a three-step method, that is, transesterification, esterification and polycondensation. The structures of BHET and WSP were identified by Fourier transform infrared spectra. Sizing performances of WSP were studied, and it was found that the surface tension of WSP size (57 mN/m, 22℃, 0.5% of weight) was lower than common sizes, the viscosity of WSP size was 1–2 mPa·S (95℃, 6% of weight) and the viscosity stability was larger than 90% at this temperature. The mixture of WSP and starch showed stronger adhesion to polyester–cotton roving and polyester roving than onefold starch. K/ S values of fibers before sizing and after desizing showed a slightly difference, which indicated that WSP would not influence the color of yarns when used as the sizing agent.

Download Full-text