SYNTHESIS AND CHARACTERIZATION OF CHLORINE-FREE POLYCYCLOTRIPHOSPHAZENE AS ADHESIVE FOR GLASS

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Date
2009-11
Authors
PONNUSAMY, RAJESWARY
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Abstract
The halogen-free phosphazene-based polymeric adhesive was synthesized via two separate steps. The first step involved the reaction of hexachlorocyclotriphosphazelle with bisphenol A in the presence of dried triethylamine that afforded, after isolation and purification, a slightly yellowish solid polymer that is designated as Pl (chlorine-bound poly[2,2-di{p-hydroxophenyl)propane]cyclotriphosphazene). In the second step, Pl was reacted with ethyl 4-hydroxybenzoate to obtain a white solid polymer that is designated as P2 (chlorine-free poly[2,2-di{p-hydroxophenyl)propane ]cyclotriphosphazene ). Both reactions were conducted in purified 1,4-dioxane under atmosphere of dried nitrogen. Pl and P2 were characterized by means of Fourier transformed infrared (FT-IR) spectroscopy, 1H and 31P Fourier transformed Nuclear Magnetic Resonance (NMR) spectroscopy, and a hyphenated system comprising Thermo gravimetric analyzer and FT -IR spectrometer (TGA-FTIR). P2 is found to be odorless, thermally stable, nonflammable and likely to be non toxic. When melted and placed in between two pieces of glass, it formed a layer of transparent adhesive. The adhesive properties of P2 were evaluated by using a tensile machine fixed with a custom made shearing fixture to measure its shear strength. For example, usage of 0.50 g of P2 provided an excellent result of 10907.50 N of shearing force, 11.19 MPa of stress and 3.38 J of energy at maximum load to break the strong bond affected by P2 between the glass plates. To further understand the level of adhesive properties of P2, the result of 0.25 g P2 in glass plates were matched with that of 0.15 g result of super glue (ethyl cyanoacrylate) available commercially. It is concluded that P2 does have a good adhesive properties which is concurrent to the market demands. However, unlike the super glue or any typical epoxy-based adhesive, P2 is free from irritants such as volatile organic compounds or petroleum distillates. Furthermore, the adhesive properties of P2 are reversible: bonded surfaces can be unglued and reglued with the same layer of P2 repeatedly as desired for the purpose of dismantling and transporting shatterable panels such as glass plates.
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Keywords
CHLORINE-FREE , POLYCYCLOTRIPHOSPHAZENE
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