Investigations on the suitability of triethylene glycol glycolate, thioglycolate, lactate, and phydroxybenzoate for the synthesis of new polyurethanes from 4,4'-diphenylmethane d i i i a n a t e were carried out. The products obtained were subjeded to physicomechanical, thermal, dielectric, and analytical tests. IR, DTA, and TG analyses were also done.
Polyurethanes belong to the group of polymers which have gained the growing appreciation of a great number of research workers as well as of many users of their products. The interest these polymers attract is due to the wide range of their advantageous properties. They have proven to be especially suitable for the production of expanded plastics, highly elastic fibers, elastomers, glues, varnishes, water emulsions, and constructional materials.13
Pursuing tests on the synthesis of new p0lyurethanes,4*~ the reactions of polyaddition of 4,4'-diphenylmethane diisocyanate (MDI) with, respectively, triethylene glycol glycolate, thioglycolate, lactate, and p -hydroxybenzoate were carried out.
The enumerated esters were synthesized in our laboratory by a standard method of esteri€ication.6 Their yields varied between 98.8% and 99.5% of the theoretical yield. The percentage composition, saponification number, acid number, and hydroxyl group content of the esters were determined. The results are given in Table I.
The esters obtained constituted the components for the synthesis of polyurethanes. The polyaddition reaction of the enumerated esters with MDI was conducted in a three-necked flask provided with a reflux condenser and electrical stirrer with a special seal.
In order to determine the most favorable reaction conditions, the process was carried out with or without a catalyst in the following solvents: toluene, dioxane, and ethyl acetate. Anhydrous lead acetate was used as catalyst. Preliminary tests proved that most favorable results were obtained when conducting the reaction in toluene without catalyst. The presence of catalyst accelerates the reaction to such an extent that at the boiling point of the mixture the reaction takes place almost immediately and the products obtained have unwanted physicomechanical properties.
The synthesis of the polymer from triethylene glycol alone and MDI was done