Synthesis and thermal studies of block copolymers from NR and MDI‐based polyurethanes

Abstract

Five series of block copolymers based on natural rubber and polyurethane were prepared from hydroxyl terminated liquid natural rubber (HTNR) and polyurethane (PU) formed by the reaction of diphenyl methane-4,4 0 -diisocyanate (MDI) with a chain extender diol, viz., ethylene glycol (EG)/propylene glycol (PG)/1,4-butane diol (1,4-BDO)/1,3-butane diol (1,3-BDO)/bisphenol A (BPA), by solution polymerization. Structural characterization of the block copolymers was done by infrared (IR) analysis. Thermal studies and kinetic analysis on thermal degradation of the block copolymers were undertaken with the view of characterizing them. Energy of activation and entropy change for the degradation were determined and a probable mechanism for the solid state degradation was suggested which corresponds to a three dimensional diffusion mechanism. DSC analysis has been used for the study of microphase separation in the block copolymers. Thermal transition of the hard segment significantly varies with the extender diol which highlights the effect of extender diol structure on the chain stiffening mechanism.

Studies on the Complexation of 3d Transition Metal Ions with NR/PEO Block Copolymer in Aqueous Medium

“…PEO and HTNR were block copolymerised using diisocyanate coupling agent to form a product, which seems to be a crosslinked material. Crosslinking may be due to the formation of allophanate linkages . This is an advantage in the present case since it leads to swelling of the polymer in aqueous medium to form a gel.…”

Polyurethane foams from oligomers derived from waste tire crumbs and polycaprolactone diols

“…There have been several studies related to the synthesis of bio‐based polyurethane using HTNR as a soft segment . Considering the biodegradation of the final material, the HTNR‐based PU are not easily biodegraded due to the chemical structure that has no ester linkage and very few bacteria strains and fungi are known to attack polyisoprene backbone.…”

Elaboration and properties of renewable polyurethanes based on natural rubber and biodegradable poly(butylene succinate) soft segments

“…Because of the presence of a double bond in the polymeric backbone, NR is suitable for chain cleavage and chemical modification affording renewable monomers, such as hydroxyl telechelic natural rubber (HTNR) . HTNR has been used as a starting material (Polyol) in the preparation of many kinds of polyurethanes . In addition, our group reported recently the preparation of bio‐based polyurethane from HTNR and poly(ε‐caprolactone) (PCL) …”