Polyethylene Vinylacetate (EVA) Student Name Pathik Patel, ID Number #20638625; E-mail: pd6patel@uwaterloo.ca
1. Introduction and Applications:
Ethene, but-3-enoic acid (IUPAC name), commonly known as poly(ethylene-vinyl acetate) (PEVA), as the name suggest, is the copolymer made up of ethylene monomer and vinyl acetate (VA) monomer. It is produced by addition reaction mechanism with free radical initiation. It has a chemical formula of (C2H4)n(C4H6O2)m.
Depending upon the weight percent of vinyl acetate, we get different polymers such as vinyl acetate modified polymer (4% VA), thermoplastic ethylene vinyl acetate (4 - 40% VA) and ethylene vinyl acetate rubber (>40% VA) with the remainder being ethylene. Properties such as toughness,
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Synthesis, Mechanism and Production
In free-radical co-polymerizations, the different reactivity of the growing polymer chain toward two different monomer molecules and the possibility of chain transfer reactions make calculations to predict polymer kinetics and composition extremely difficult.
The first equation shows ethylene-terminated polymer radical reacting with vinyl acetate, and the second equation shows vinyl acetate terminated polymer radical reacting with ethylene. The propagation rate coefficient are used to find the reactive ratios. It is even possible to consider the effects of penultimate groups. It is observed that longer alkyl chain has little effect on the kinetic parameters. However, it was noted that there is a relatively small penultimate unit effect, if any, for this copolymerization.
The reactivity ratios for ethylene-vinyl acetate copolymerization have been measured by a number of workers, and vary from r1 = 0.13 to 0.88 and r2 = 0.72 to 3.74, where r1 = k11/k12 and r2 = k22/k21.
Reactivity ratios are sensitive to reaction temperature, pressure and media, which accounts in part for the broad range reported. the lower temperature and higher pressure conditions increases the reactivity ratios slightly. The table below depicts Reactivity Ratios at Various Temperatures for Ethylene-Vinyl Acetate Co-Polymerization, Where 1 = Ethylene and 2 = Vinyl
The goal of this two week lab was to examine the stereochemistry of the oxidation-reduction interconversion of 4-tert-butylcyclohexanol and 4-tert-butylcyclohexanone. The purpose of first week was to explore the oxidation of an alcohol to a ketone and see how the reduction of the ketone will affect the stereoselectivity. The purpose of first week is to oxidize the alcohol, 4-tert-butylcyclohexanol, to ketone just so that it can be reduced back into the alcohol to see how OH will react. The purpose of second week was to reduce 4-tert-butylcyclohexanol from first week and determine the effect of the product's diastereoselectivity by performing reduction procedures using sodium borohydride The chemicals for this lab are sodium hypochlorite, 4-tert-butylcyclohexanone
Every 5 minutes, a small amount of mixture was dissolved in acetone (0.5 mL) and was spotted onto a thin layer chromatography (TLC) plate, which contained an eluent mixture of ethyl acetate (2 mL) and hexanes (8 mL). The bezaldehyde disappearance was monitored under an ultraviolet (UV) light. Water (10 mL) was added after the reaction was complete, and vacuum filtrated with a Buchner funnel. Cold ethanol (5 mL) was added drop-by-drop to the dried solid and stirred at room temperature for about 10 minutes. Then, the solution was removed from the stirrer and place in an ice bath until recrystallization. The recrystallized product was dried under vacuum filtration and the 0.057 g (0.22 mmol, 43%) product was analyzed via FTIR and 1H NMR
The experimental Fischer esterification of 8.92g of acetic acid with 5.0g of isopentyl alcohol using concentrated sulfuric acid as a catalyst yielded 4.83g (65.3% yield) of isopentyl acetate. The product being isopentyl acetate was confirmed when the boiling point during distillation had similar characteristics to that of the literature boiling points2. Physical characteristics like color and smell also concluded a match of our product with what was intended. 1H-NMR spectroscopy analysis supported this claim due to the fact that the integration values and chemical shifts were comparable to isopentyl acetate. Lastly, infrared spectroscopy (IR) showed similar key characteristics of our product’s wavelengths to that of pure isopentyl acetate5.
At a constant temperature, a pure liquid has a vapor pressure that describes the pressure of escaped gaseous molecules that exist in equilibrium at the liquid’s surface. Adding energy to a pure liquid gives more molecules the kinetic energy to break the intermolecular forces maintaining the liquid and raises the overall temperature of the liquid. Eventually, adding energy boosts the liquid’s vapor pressure until it equals the surrounding atmospheric pressure. When this occurs, the pure liquid boils at a temperature called the boiling point.
In this lab 4-tert-butylcyclohexanone is reduced by sodium borohydride (NaBH4) to produce the cis and trans isomers of 4-tert-butylcyclohexanol. Since the starting material is a ketone, NaBH4 is strong enough to perform a reduction and lithium aluminum hydride is not needed. NaBH4 can attack the carbonyl group at an equatorial (cis) or axial (trans) position, making this reaction stereoselective. After the ketone is reduced by the metal-hydride, hydrochloric acid adds a proton to the negatively charged oxygen to make a hydroxyl group. The trans isomer is more abundant than the cis based on the results found in the experiment and the fact that the trans isomer is more stable; due to having the largest functional groups in equatorial positions.
Strength In terms of strength the effect the plasticizers have on the polymers is that the additive makes the polymer have a weak intermolecular force. As a result of this the polymers will be unstable an easier to handle. Due to this the polymer then can be remoulded and tougher and this will increase the polymers
Spinning is a process that involves forcing the liquefied polymer solution through a ‘die’ (small hole). The crystallinity of Kevlar Polymer strands, contributes to the unique strength and stiffness of the material. Kevlar is very similar to other common synthetic polymers, including Nylon, Teflon and Lycra. In all polated to strength. Aromatic refers to the Carbon atoms attached to a ring, and Amides refers to a group of Carbon, Nitrogen and Hydrogen atoms.
It is a thermoplastic resin that is retrieved by the polymerization of ethylene. PE is a semi-crystalline polymer that has excellent chemical stability. Specifically, it is able to store high quantities of water insoluble components, such as most volatile molecules, due to its polyolefin nature. This occurrence is known as the aroma scalping, which causes a diminishment of content of aroma and/ or an imbalance. The stiffness, hardness and strength of the PE attain greater heights with an increase in the density of chain branches. Not only do containers made up of PE form stiff and strong holders, but they also lead to reduced moisture vapour transmission and clarity or transparency based on the density of polymer
Before using ethylene to produce polyethylene, the compound needs to be purified to almost 100%. In order to reach this level of purity the ethylene needs to be freed of olefins, acetylenes, dienes and water through several processes such as: driers are used to take out the water, a demethanizer is used to remove methane, etc. ...
It is a kind of plastic that originates from consolidating ethylene (found in unrefined petroleum) and chlorine (found in salt). At the point when joined together these substances get to be Polyvinyl Chloride (PVC) gum, or as it is better known - Vinyl. It is then further handled to be made more adaptable, inflexible, semi-fluid, clear or bright, thick or thin.
The synthesis of polymers starts with ethylene, (or ethene). Ethylene is obtained as a by-product of petrol refining from crude oil or by dehydration of ethanol. Ethylene molecules compose of two methylene units (CH2) linked together by a double carbon
spaced –CONH– amide groups. Nylon 6-6, or poly(hexamethylneadipamide), is composed of. two structural monomers (hexamethylendiamine (H2N(CH2)6NH2) and adipic acid. (HOOC(CH2)4COOH), whereas Nylon 6, or poly(6-caprolactam), is composed of a single structural unit (either 6-aminocaproic acid (H2N(CH2)4COOH) or caprolactam). Ultimately, the answer is yes.
German Chemist Hans von Pechmann first synthesized Polyethylene by accident in 1898 by heating diazomethane. His colleagues characterized the waxy substance polyethylene due to the fact that they recognized that it consisted of long ethene chains. It was then first industrially synthesized by accident in 1933 by applying extremely high pressure to ethylene and benzaldehyde. Over the years, development of polyethylene has increased due to the additions of catalyst. This makes ethylene polymerization possible at lower temperatures and pressures.1
This research brought me experience in many areas of material science: monomer preparation and purification, polymerization, polymer precipitation, and film casting. I created the monomer and worked through every step to film production and testing without needing supervision. I also had to learn and perform air-free techniques involving glove boxes and Schlenk lines. Difficulties with the different reaction conditions and ratios needed for each monomer to form correctly made every run a test of
Falak Mdahi Chem 203.2 The Synthesis of Acetanilide from Acetic Anhydride and Aniline Introduction Recrystallization is a technique used to purify solids that contain small amounts of impurities. It is used to isolate pure solids from a supersaturated solution, leaving the impurities in the solvent (1). The solid containing the impurities is placed in a hot solvent and upon cooling the compound precipitates to its purified form while the impurities are left behind in the solvent (1). There are six steps when it comes to undergoing a recrystallization of a solid.