4.7 Latex Compounding
All compounding ingredients are commercial chemicals, used without further purification. Aqueous dispersion of sulphur (S), zinc oxide (ZnO), zinc diethyldithiocarbamate (ZDEC) and antioxidant were prepared by ball milling for 48-72 hours. The concentrated NR latex was compounded according to the formulation shown in Table 4.4. After compounding, the mixture was stirred slowly and allowed to mature at room temperature (ca. 28-30 C) for 24 hours or until the mixture reaches the chloroform number of 3 and % quick swelling in toluene of 90-95%. Methods of measurements of chloroform number and % quick swelling are given in Sections 4.8.7 and 4.8.8, respectively.
Table 4.4 Formulation for preparation of prevulcanised
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It is measured by precipitating the latex in acetic acid and dried. Approximately 5 g of latex was weighed into the stainless steel pan. The latex was coagulated by sufficient amount of 5% v/v acetic acid, while stirring constantly. The latex was then placed onto a steam bath to complete the coagulation. The coagulum was then rolled as a thin sheet with a small two-roll mill with simultaneously washed with water. The coagulum sheet was dried in an oven at 70°C for 16-20 hours. The drying and weighing process was repeated until the weight was constant to within 1 mg or less. The DRC was calculated by the following …show more content…
The liquid sample was poured into acetone-cleaned glass container of 30 mL and placed on the stage. The platinum-iridium ring was cleaned by washing in water and then heating in a flame, taking care to avoid distorting the ring. The ring was submerged below the interface by moving the stage where liquid container is placed. After immersion, the stage was gradually lowered and the ring pulled up the meniscus of the liquid. Automatically, in alternated direction, the stage was gradually increased and the ring pushed down. The surface tension was calculated based on the measurement of the maximum force and averaged from ten times of pulling and pushing of the ring.
4.8.7 Vulcanisation Level by Chloroform Number Test The chloroform number test was performed through the coagulation of a sample by mixing the latex with an equal volume of chloroform. After 2-3 minutes, the coagulum was examined and graded according to the texture of the coagulum. The chloroform number was expressed as shown in Table 4.5.
Table 4.5 The expression of chloroform number test [86]
Coagulum form Chloroform number Vulcanisation
Cumulatively these three methods resulted in the determination of the percent purity for each type of aspirin.
Firstly, an amount of 40.90 g of NaCl was weighed using electronic balance (Adventurer™, Ohaus) and later was placed in a 500 ml beaker. Then, 6.05 g of Tris base, followed by 10.00 g of CTAB and 3.70 g of EDTA were added into the beaker. After that, 400 ml of sterilized distilled water, sdH2O was poured into the beaker to dissolve the substances. Then, the solution was stirred using the magnetic stirrer until the solution become crystal clear for about 3 hours on a hotplate stirrer (Lab Tech® LMS-1003). After the solution become clear, it was cool down to room temperature. Later, the solution was poured into 500 ml sterilized bottle. The bottle then was fully wrapped with aluminium foil to avoid from light. Next, 1 mL of 2-mercaptoethanol-β-mercapto was added into fully covered bottle. Lastly, the volume of the solution in the bottle was added with sdH2O until it reaches 500 ml. The bottle was labelled accordingly and was stored on chemical working bench.
In this work, the mechanical and barrier properties were examined for Polypropylene (PP) film in which the surface of the film was modified by Oxygen plasma treatment. The PP film was treated in various intervals of time of 60 s, 120 s, 180 s, 240 s and 300 s with three various RF power settings of 7.2 W, 10.2 W, 29.6 W. The contact angle was measured to characterize the wettability. The oxygen functional groups were generated on the surface of oxygen modified PP which was observed by Fourier transform infrared spectroscope and it was resulted in the improvement of wettability. The surface morphology and roughness of the PP films before and after the oxygen plasma treatment was analyzed by Atomic Force Microscopy (AFM). It was found that the roughness of
The lab begins with reflux of the reaction to form an ester, followed by several extractions from an organic layer. To purify the ester, the compound is dried by gravity filtration with a drying agent, distilled using simple distillation, and recrystallized. The aldol condensation is reacted in a test tube and the solute is collected via vacuum filtration and recrystallized. The esterification procedure was performed first. To begin the lab, the heating mantle was set at the 6 setting, and the hot plate heat was turned on to low.
Ensure gloves are worn at all times when handling strong acids and bases within the experiment of the preparation of benzocaine. 4-aminobenzoic acid (3.0g, 0.022 moles) was suspended into a dry round-bottomed flask (100cm3) followed by methylated sprits (20 cm3). Taking extra care the concentrated sulphuric acid of (3.0 cm3, 0.031 moles) was added. Immediately after the condenser was fitted on, and the components in the flask were swirled gently to mix components. It should be ensured that the reactants of the concentrated sulphuric acid and the 4-aminobenzoic acid were not clustered in the ground glass joint between the condenser itself and the flask. In order to heat the mixture to a boiling point, a heating mantle was used and then further left for gently refluxing for a constituent time of forty minutes. After the duration of the consistent forty minutes the rou...
The actual amount of crude product was determined to be 3.11 grams. The percent yield of the crude product was determined to be 67.75 %. The actual amount of pure product formed was found to be 4.38 grams. The percent yield of the pure product was determined to be 95.42%. Regarding the thin layer chromatography, the line from the solvent front is 8 centimeters.
About 1 gm. coarse powder was weighted and transferred to a 500 ml conical flask containing 100 ml of water. It was maintained at moderate boiling for 30 minute on water bath. It was cool and filtered in to a 100 ml volumetric flask. Volume was diluted by adding sufficient amount of water. The decoction was poured in test tube, and then shaken in a lengthwise motion for 15 seconds. They were allowed stand for 15 minutes and the height of foam was measured to determine the foaming index.
The mixture was poured through a weight filter paper and Sucrose washed with a 5ml of dichloromethane. The resulting solid was left in a breaker to dry for one week, to be measured. Left it in the drawer to dry out for a week and weighted it to find the sucrose amount recovered amount.
The pure compound melting point should be in the range of 169-172 ℃. During this lab practical Paracetamol- acetaminophen will be synthesis, purified and recrystallized again. The purpose of the experiment was to learn basic recrystallization techniques that include hot and cold filtration
During the incubation, in an Erlenmeyer flask, 1X Tris Acetate EDTA (1 mL) and powder agarose (0.4 g) were dissolved in dH2O (49 mL). Then the solution was microwave for 2 minutes and allowed to cool to room temperature. Then SafeRed concentrate (2.5 µL) was added to the solution and it was poured into the gel box and allowed to solidify.
The solvent should be easily removed from the purified product, not react with the target substances, and should only dissolve the target substance near it’s boiling point, but none at freezing. A successful recrystallization uses minimum amount of solvent, and cools the solution slowly, if done to fast, many impurities will be left in the crystals. Using the correct solvent, in this case ice water and ethyl acetate, the impurities in the compound can be dissolved to obtain just the pure compound. A mixed solvent was used to control the solubility of the product. The product is soluble in ethanol an insoluble in water. Adding water reduced solubility and saturates the solution and then the crystals
About 25ml of distilled water was added. Then 2-3 drops of phenolphthalein indicator solution were put in. It was swirl to dissolved the solid.
Joseph F. Ackerman, Newport, Ky., and John F. Jones, US Patent No. 2,923,692, Mucilaginous composition comprising salt of cross linked carboxylic polymer and method of preparing same, (Feb. 2, 1960).
We took pictures of each other’s data once finished with the lab. For the paper chromatography, students began by grinding 5g of spinach along with 2g of anhydrous magnesium sulfate. Students added hexanes and acetone as specified by the lab protocols. Once, the solvent was a dark green color, we placed it in a centrifuge and transfer the liquid portion of the solution into a test tube. Throughout this portion of the experiment, students used weighting paper as a funnel poring the indicated solution as stated by the protocol, for instance pouring silica gel and sand into the column. After, we poured about 3ml of Hexanes into the column, making sure not to let the column dry. We then added, spinach extract to the column—after, we added about 1ml of hexanes. Adding hexanes caused the solution to gain a yellow colored band. We added hexanes until the yellow band reached the bottom of the column, thus began to collect all the yellow pigment into a test tube. Once the elutant become colorless, we once again placed a waste basket under it. Finally, we collected the green pigment into another test tube by a 70%/ 30% mixture and a bit of acetone. Once the two colored bands were collected, we obtained the wavelengths of each colored band using the
The mixture was then cooled. Vacuum filtration was then performed on the mixture. This was done by carefully rinsing the precipitate mixture over moist, pre-weighed filter paper into a Büchner flask under vacuum. The residue was then moistened with ethanol while the flask was still under vacuum. The residue and filter paper were placed on a pre-weighed watch glass and weighed. They were then placed in a drying oven for about fifteen minutes and then reweighed. They were reweighed after a further five minutes in the oven and then again after another five minutes, so as to ensure the precipitate had been fully dried.