Production of a Non-Isocyanate Polyurethane (NIPU) Polymeric Material for Adhesive or Plasticizer Applications from Castor Oil and Chitosan

Abstract

ABSTRACT : A new bio-based non-isocyanate polyurethane (NIPU) material was developed from castor oil (Ricinus communis) and chitosan through various adequation steps and a polymerization reaction. The main research problem tackled in this project was the possibility of the reaction between amino groups of chitosan and cyclic carbonate groups through an aminolysis reaction to yield urethane or carbamate bonds. Many reports have been published about this reaction with different substrates, mainly in homogeneous conditions using carbonated and aminated substrates. Carbamate bond production from amine groups of polysaccharides like chitosan has been broadly studied through the reaction with chloroformates (chloroformic acid esters), but only one report was found on the attempt to produce carbamate through carbonate-amine aminolysis (Aiba, 1993). Indeed, this work uses chitosan as an aminated substrate and linear carbonates such as diethyl and dimethyl pyrocarbonates. To the best of the author’s knowledge, this is the closest study to what was intended to be done in this project, as no cyclic carbonates have been used in this reaction. In the project, several defined processing steps for castor oil can be identified: epoxidation and carbonation. In the epoxidation step, the mass transfer limitation involved in the performance of the catalyst was studied. A factor significance study and an optimization of the reaction parameters were carried out using response surface experimental designs. Some pilot-scale runs were also done to study the behavior and the evolution of temperature. At the epoxidized castor oil carbonation step, the apparent improving effect of water in the reaction was studied. The aminolysis reaction was studied using a simple fatty-carbonated substrate like carbonated methyl oleate and short amines like n-butylamine and its derivatives. Kinetic studies were conducted at this stage. Then, carbonated methyl oleate and carbonated castor oil were reacted with glucosamine hydrochloride, which is the monomeric unit of chitosan. Characterization by nuclear magnetic resonance and Fourier transform infrared spectroscopy allowed the identification of carbamate bond production. Finally, carbonated castor oil was reacted with aqueous chitosan in an emulsion system, and the product was used as an additive for a commercial adhesive product, Autodhesan®, from ANDERCOL Co., an Akzo Nobel team member. The final product showed improved performance characteristics for the adhesive.