Krishna Dutt

A review on synthesis of value added products from polyethylene terephthalate (PET) waste

Many research papers have been contributed by several authors for making PET waste recycling economically and ecologically more viable. Recycling of PET waste was started in last two decades. Most of the authors are devoting their time in getting economically viable solution for development of methods based on either mechanical or chemical recycling. Some success has been obtained in development of chemical recycling methods which provides value added products from PET waste. However, different products developed by chemical recycling have not provided economically enough and reliable methods of recycling of PET waste.

Thermal Stability and Crystallization Behavior of TER Blends of Isotactic Polypropylene (iPP)/Ethylene-Propylene Diene Rubber (EPDM)/Nitrile Rubber (NBR)

The blends of isotatic polypropylene (iPP), ethylene-propylene diene rubber (EPDM), and nitrite rubber (NBR) were prepared using dimethylol phenolic resin as a crosslinking system. The dynamically crosslinked blends of iPP/EPDM/NBR showed superior thermal stability to that of virgin isotactic polypropylene (iPP). Dynamic crosslinking rendered the vulcanizate thermally more stable as compared to uncrosslinked blends, which can be attributed due to the variations in degree of crosslinking and degree of crystallinity. Crystallization of iPP in the blends of iPP/EPDM/NBR was also studied through Temperature Modulated Differential Scanning Calorimetry (TMDSC). Other detailed analysis of endotherm peaks obtained after first and second melts in terms of heat of enthalpy, degree of undercooling, and degree of crystallinity were also evaluated. Various kinetic parameters were also determined. Degree of crosslinking increases the interfacial adhesion between the iPP and EPDM/NBR phases. Dimethylol phenolic resin used as a compatibilizer also enhanced the thermal stability of the iPP/EPDM/NBR blends.

Eco-friendly synthesis of PET-based polymeric plasticiser and its application in nitrile-PVC rubber blends

ABSTRACT We report a robust synthesis of polymeric plasticiser from the post-consumer plastic waste, i.e. poly(ethylene terephthalate) (PET) and its subsequent use as plasticiser for preparation of nitrile rubber (NBR) and nitrile-PVC rubber blends. PET waste was depolymerised by alcoholysis with the help of 1-decanol. The obtained oligomeric plasticiser was characterised for its chemical structure using Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance. The prepared polymeric plasticiser was then used for the preparation of nitrile and nitrile-PVC blend rubber sheets. NBR and nitrile-PVC blend rubber sheets were also prepared by using dioctyl phthalate as plasticiser. The fabricated sheets were compared for their mechanical properties such as tensile strength, elongation at break, hardness. The effect of ageing on mechanical properties was also analysed. It was observed that the use of polymeric plasticiser resulted in significant improvement in tensile properties and ageing resistance. This eco-friendly synthesis of plasticiser offers its use for high-performance applications.

Kinetic Studies on Cure Kinetics of DGEBA (Diglycidyl Ether of Bisphenol-A) with Terephthalamide Hardening System generated from PET waste

Abstract: An aromatic amide system for epoxy resin based on diglycidyl ether of Bisphenol-A was developed through ammonolysis of PET waste. The ammonolysis of PET waste was carried out at ambient conditions of temperature & pressure. The end product, characterized as terephthalamide was used as hardener in epoxy resin (Diglycidal ether of Bisphenol-A) and triethylamine and sodium hydroxide were used as catalysts. Several samples were used to study the curing kinetics having varying amounts of the catalysts by means of Differential scanning calorimetry (DSC). Isothermal and Dynamic DSC characterization of the formulations were performed. The curing kinetics of terephthalamide with epoxy resin shows high energy of activation as 50.18 KJ/mole in the absence of catalyst which was lowered towards negative values in their presence. The optimum curing of epoxy resin heated with aromatic hardener can be obtained in 28 minutes at 320 EsC. The use of catalysts reduced the curing time to 2.0 minutes at 60 EsC.