IndexIntroductionExperimental results and discussionConclusionThis laboratory involves the synthesis of an acrylic polymer. Hydroxyethyl acrylate, styrene, and butyl acrylate reagents were reacted in a semi-batch process. The product was then stored for a week before being cross-linked with a melamine-formaldehyde resin and a catalyst. The resulting coating was applied to an Al panel, cured and tested according to ASTM D5402 for solvent resistance. This process was repeated and the formulation was adjusted until a formulation exceeded 200 MEK double rubs. The formulation was then created in a larger batch and applied to aluminum, steel, and free film substrates using pick-up bars. These samples were then processed and characterized using various ASTM methods based on mechanical and chemical properties. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay IntroductionAcrylic resins were first used in the 1950s in the automotive industry. They have since increased their durability and practicality. Acrylic resins are formed by radical chain polymerization. This process has three phases: initiation, propagation and termination. The formation of a radical is what initiates this polymerization. That radical species is then able to react with the monomer to produce a carbon radical on the monomer. This new radical can then react with other monomers creating an increasingly longer monomer chain. This polymer continues to grow pushed forward by the reactivity of the radical until it is terminated by another radical or other means. The goal of this lab is to successfully synthesize an acrylic resin with favorable PDI, then cross-link the polymer with melamine-formaldehyde. This reaction appears to create a coating that can be tested using numerous characterization techniques following ASTM. Experimental The first step of this experiment was the synthesis of acrylic resin. A semi-batch process was used in this synthesis. Xylene (100.0 g) was added to the resin kettle and began to heat up to 90°C. A flow of nitrogen was then started which covered the entire apparatus. Special care was taken not to have excessive flow to preserve the solvent. While the solvent was heating, hydroxyethyl acrylate (15.0 g), styrene (82.6 g), butyl acrylate (52.5 g), and Vazo 67 (3.75 g) were mixed in a flask Erlenmeyer until the initiator, Vazo 67, was completely melted. This solution was then added to an additional funnel that flowed into the xylene kettle. The monomer solution began to settle drop by drop into the heated solvent. The temperature was monitored constantly. The temperature goal of the addition period was 90-95°C. To control the temperature, the cloak was turned off and lowered to cool and raised and turned on to warm. This back-and-forth heating and cooling cycle created predictable and consistent heating throughout the addition. The entire addition took 56 minutes. Once the entire monomer solution was added, the batch was held at 90-95°C for another 30 minutes. A portion of xylene (2.5 g) and Vazo 67 (0.5 g) was added directly to the kettle after this waiting period. The temperature was then maintained for another hour. This complete synthesis was followed by cooling the resin and storing it for future use in a sealed jar. One week after the synthesis, theformulation with a cross-linker together with characterization. The first test was to determine the percentage of solids according to ASTM D2369. The percentage of solids was determined to be 51.88%. With this information, a formulation with the cross-linker Cymel 303 can be calculated. The formulation of synthesized resin (10.00 g), Cymel 303 (1.30 g) (25%) and pTSA (0.026 g) (0.5 % ) was prepared with a drop of the flow aid, Byk 301 in solvent. This was then drawn onto an aluminum panel which was chemically cleaned with solvent. The drawdown was carried out with a 5 mil bar. The panel was left to dry for 15 minutes before being placed in an oven at 160°C for 20 minutes. To test hardening, MEK double rubs were conducted according to ASTM D5402. If the coating has survived more than 200 rubs without failing, the formulation passes and can be used for further testing. The initial formulation failed at 50 rubs. The formulation was adjusted two more times with the same formulation as indicated above, except that the amount of catalyst, pTSA, was increased with each new formulation. The final successful formulation contained the synthesized resin (20.09 g), Cymel 303, (2.63 g) (25%), and pTSA (0.21 g) (2%). This formulation has successfully passed 200 rubs and has been used to coat aluminum and steel panels. A glass panel was also used to obtain a thin film and for gloss measurements. These aluminum and steel panels were subjected to numerous ASTM test methods explained in the Results and Discussion section. Results and discussion The Tg value (theoretical) was calculated to be 16.18°C of the synthesized resin. The Tg measured using DSC was found to be 35.55°C. The Tg of the thin film coating was also measured using DSC and yielded 57.39°C. DSC test results differ from theoretically calculated ones. This difference is worth noting. The temperature was kept constant within the range during the entire experiment (discarding the startup). The range was 90.0-94. 9°C. One possibility for this variation is the use of older reagents. It is possible that self-polymerization has begun in any of the reagents used. This would also explain the variance in the PDI. A more likely source of this difference may be direct addition rate. The rate at which the monomer solution was added was not at all constant throughout the addition with a rate range of 20 to 40 ml per 10 minutes. This would lead to variations in the length of the chain. An advantage of semi-batch synthesis is that it is possible to control the rate of monomer addition. The idea is to maintain a constant flow throughout the polymerization. This has not been maintained and results may vary because of this. DMA should have been performed on the thin film, but the film was too fragile and impossible to measure. Despite maintaining the temperature, the monomer conversion rate was less than 99%. This is known thanks to the solids percentage value. A solids percentage value of 66% would have given a more promising conversion rate. This value could have been increased by maintaining a constant flow and heating the sample longer and with a slightly larger amount of initiator. This would increase your conversion rate, but could lead to other problems with PDI. This synthesis must be performed in one go. Initiation, propagation, and termination are not processes that can simply be paused. If the temperature were to drop to room temperature, termination could terminate early and leave the monomer.