Four novel phenol-formaldehyde resins having pendant citraconimides in their repeating units were synthesized via condensation of formaldehyde with N-(hydroxy phenyl) citraconimides under conditions similar to those used in novolac preparation. The prepared resins were modified by using two methods the first one involved esterification of phenolic hydroxyl groups via treatment of the resins with different acid chlorides in the presence of triethyl amine producing sixteen new resins while the second method involved free radical polymerization of citracon vinyls of the pendant citraconimides producing four new cross-linked thermally stable polymers. Both the prepared and the cured resins have new properties which may serve different applications. Introduction Phenol-formaldehyde resins are the oldest commercial synthetic polymers, they exhibit excellent electrical and chemical resistance and retention of properties after long term exposure to high temperatures (1-4). These resins are used in a wide variety of applications including adhesives, surface coatings, binders and molding, therefore not surprisngly a number of synthetic strategies have been carried out to incorporate structural modifications in these resins to obtain new properties serving new applications (5-8) .
1. The variation of the ordering in polyvinyl chloride and polymethylmethacrylate precipitated from solutions in the process of heat treatment was studied. 2. The intensity curves calculated from the electronographic (electron diffraction) data show that the heat treatment leads to the formation of a more ordered arrangement of the chain molecules of these amorphous polymers. 3. The variation of the degree of ordering in these polymers in the heat-treatment process causes a change of the mechanical properties of the polymers and of their capacity for reprocessing. 4. From the data obtained we may conclude that the form of the polymer molecules and their mutual arrangement in the solution differ from those in the condensed state.
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