Glycidoxypropyltrimethoxysilane Synthesis

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Glycidoxypropyltrimethoxysilane (GPTMS) and Bis (3-trimethoxysilyl-propyl) amine (Dynasylan 1124 ®) are provided by Evonik Industries, USA. Heloxy Modifier 65® (EEW=230) and epoxy resin (EPON 828 ®, EEW=188) are supplied with Momentive, USA. Isophorone diisocyanate (IPDI) is supplied by Bayer Material Science. Colloidal silica Ludox HSA is provided by Grace Davison. Brulin 815 GD is obtained from Brulin & company Inc. Mercaptanbenztriazol (MBT) (corrosion inhibitor) and all other chemicals and solvents are purchased from Sigma-Aldrich, and used without any modifications. Aluminum alloy AA2024-T3 panels are supplied by ACT panels LLC, USA. EPON 828 and Heloxy Modifier 65 (7.4 g) and anhydrous ethanol (40 g) are charged to three neck flask attached…show more content…
Reaction is carried out in a 500 ml three-neck flask supported on a heating mantle and provided with a mechanical stirrer, a water condenser, a thermometer probe with an inlet for dry nitrogen gas, and an addition funnel. The calculated amount of IPDI and THF are charged to the three- neck flask under mechanical stirring and BTMSPA is added slowly from the addition funnel at a rate to maintain the reaction temperature below 50°c. After addition of BTMSPA is complete, mixture is stirred for additional 1 hour at room temperature. The completion of the reaction is verified by FT-IR following the disappearance of peak associated with NCO groups. The obtained solution is transferred to a single-neck flask and by using a rotary vacuum evaporator THF is distillate in two steps and replaced by dry ethanol to yield around 60-65% solution. The bis-ureasil solution is transferred into an air-tight container and stored under refrigeration. Preparation of epoxy based sol-gel…show more content…
In the first step, the panels are scrubbed with a sponge side of Scotch Brite pad dipped in a 10:1 mixture of tap water and Brulin 815GD at room temperature followed by rinsing with tap water and checked for “break-free” test by immersion in de-ionized water. The panels, then immersed 5 minutes in the tap water/ Brulin 815 GD (10:1) circulating bath are heated to 65°C, and then rinsed by 10 dunks in tap water immersion followed by spraying of low pressure de-ionized water. The panels are then immersed in a circulating de-oxidizing bath for 2 minutes, and then 10 dunks immersion in tap water following by low pressure spray of de-ionized water. Deoxidizing bath contains 35% butyl alcohol, 25% isopropyl alcohol, 18% phosphoric acid, and 22% de-ionized water (by vol.). Panels are placed vertically in a panel stacker for drying and are applied with coatings within 3 hours. Application of sol-gel coating All coatings are applied at room temperature (25–30˚C) using an automatic dip coater (PTL-200, MTI Corporation), at an immersion/withdrawal speed of 15–17 cm/minutes, with a residence time of 15–20 seconds. After application, the panels are placed vertically in a panel stacker for 15 minutes of air drying, followed by 30 minutes of thermal curing in an air circulating oven at 120°C. The typical dry-film thickness of coatings should be

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