3.4 Latex Film Formation
The process of transforming a stable dispersion of colloidal polymer particles into a continuous film is called “latex film formation”. It involves many steps that span from a dilute through to a concentrated dispersion, into a packed array of particles, and eventually into a continuous polymer film. From a modeling perspective, it is conventional to split the process into three sequential steps (drying, particle deformation, and diffusion) which each steps can overlap in time [37-40].
The film formation process, sketched in Figure 3.8, has a pronounced influence on the final film properties. When a stable dispersion (state 1) is deposited on a surface and subject to evaporation (stage 1), the particles consolidate
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The rate of evaporation has been determined as being the same as the rate of evaporation from water. The first stage is the longest of the three until the polymer has reached approximately 60-70% volume fraction or until the surface area of the liquid-air interface starts to decrease as a result of solid film formation. The second stage starts when the particles first come into irreversible contact. The rate of evaporation per unit area of open wet latex remains constant, but the overall rate of evaporation decreases greatly during this stage. Reducing of the rate of evaporation can lead to better quality films by allowing the particles more time to pack into an order structure.
The last stage starts with the initial formation of a continuous film. The remaining water leaves the film initially via any remaining interparticle channels and then by diffusion through the fused polymer skin, but the rate of evaporation eventually slows to approach that of diffusion alone.
The spatial distribution of particles in latex film is important in determining the evaporation rate as well as the resulting film microstructure. The observation is that inhomogeneities are observed both in the vertical and in the horizontal (in the film plane)
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Dry sintering is a common mechanism in other types of particulate materials, such as ceramics made from oxide powders. It was originally proposed by Dillon et al. [48], important experimental evidence is presented by Sperry et al. [49] who followed the cloudy-clear transition of a film by using a minimum film formation temperature bar. Their results prove that water is not relevant in the deformation around the cloudy-clear transition, at least for the acrylic films. They concluded that the film formation process can be separated into two independent steps. In the first, water evaporates completely and in the next, particles are deformed due to polymer-air interfacial tension and van der Waals
Hypothesis- Water will evaporate the quickest because there isn't heavy sugars in the drinks slowingdown the evaporation process.
lower the rate of reaction until it is too high for a reaction to take
The film Declining by Degrees effectively argues its claim that all is not right in higher education. They do this by interviewing countless professors and students that still attend college or that have recently graduated or dropped out. Their use of personal experiences, statistics, and expert opinions helps build their credibility and emotional appeal for the viewers of the documentary. The main audience for this documentary being anyone who cares about college, parents, students, and even the professors and staff at colleges in the United States.
...pping, painting and spraying. When making things with liquid latex many layers are recommended to make it more durable. Unlike lifecasting a mold isn’t needed when using liquid latex and it can be directly applied onto the skin. Many different types of fabrics can be used with latex as well, almost any type of fabric can be used as long as the latex is sitting on top of it and its being mixed in with the different fibers in the fabric. When removing liquid later after it has been dried it can easily be peeled off, if the latex is sticking to that material applying oil or lotion to the edges makes it easier to remove.
The hypothesis for this experiment was, If three different types of waters (saltwater, fresh water, tap water) are tested, then the liquids won’t evaporate at the same rate and tap water will evaporate at the fastest rate because it won’t have any non-volatile substances to hold it back from evaporating.
The objective of this experiment was to investigate the relationship of dispersion forces and hydrogen bonding forces in intermolecular attractions through the evaporation of different substances. Using temperature probes, the endothermic process of evaporation is measured by inserting the probes into the substance and then taking them out to allow the substance to evaporate, the change in temperature of the substances showed if a lot or not a lot of evaporation occurred and over how long the evaporation took place depending on if the change in temperature was high or low.
In his documentary Classified X, Martin Van Peebles describes three areas where African-Americans could be receive some sanctuary from the racism that pervaded almost all Hollywood films. These three places were: the Hollywood version of an all-Black film, the church, and entertainment. Black culture and music is prominent in mainstream society, but the people behind this culture don’t always receive recognition and respect for their creations. Mainstream White pop culture excitedly consumes and appropriates Black culture, but disrespects the source.
I chose to analyze Despicable Me, an animated film geared towards a younger audience, because I was interested in examining underlying theories and messages that this film would be relaying to its viewers. Often times, when watching animated films, children are not aware of these messages, as they are absorbed by the characters, special effects, and humor. But as we have learned throughout this semester, our brains are subconsciously primed by the various surroundings we are exposed to. Since we also studied the impacts of entertainment, such as television and video games, on children, I wanted to see how a popular children’s film might also affect them.
The ingredients used in making slime contain fundamental additives that, when mixed together, cause the thick, gooey, slime every kid enjoys. Polymers are made from several smaller molecules joined by chemical bonds. The polyvinyl allows the mixture to feel slimy. Combing the polyvinyl and Borax together creates a chemical reaction. The mixture becomes cold, thicker, and elastic. This combination mixed together produces slime that is fun and safe for all ages.
With this short but very interesting and informative class I have just scratched the surface of the what it takes to make a full fleged film. It takes much more than I had presumed to make a movie in Hollywood. The number of people that it takes to make a minute of a movie let alone the entire movie was astonishing to me. There are many things that it takes to start making a movie but without an idea of some sort there is no movie to be made.
According to Al-Amri, (2000) evaporative cooling is the chill that the person feels when his skin stroked by a breeze. With the energy of the human body, the water on the skin will be evaporated by the air. By using high-pressure pumps, the water will be forced through the misting nozzles creating tiny water droplets with less than ten microns size. The created water droplets will then absorb the heat (energy) that is existed in the environment quickly and evaporate to become a gas or water vapor. The used heat or energy to change the water from the liquid phase into gas is subtracted from the environment, and then the air will be cooled (Gupta et al., 1995).
The rate of evaporation can increase if the gas pressure decreases around the liquid. Heat energy is used to break the bonds that hold water molecules together, that is why water easily evaporates at the boiling point but evaporates much slower at the freezing point. Net evaporation happens when the rate of evaporation surpasses the amount of condensation. Saturation occurs when these two process rates are equivalent when the humidity of the air is at one-hundred percent. On average, a fraction of the atoms in a glass of water has enough heat energy to escape from the liquid. Evaporation from the ocean is the primary device for supporting the surface-to-atmosphere part of the water cycle. Evaporation is the pathway where water moves from the liquid state back into the water cycle as atmospheric vapor. Studies have shown that the major bodies of water are nearly ninety percent of the moisture in the atmosphere from the evaporation of the water, the ten percent left is contributed from plant transpiration. Evaporation can only occur when water is available. It also requires the humidity of the surrounding atmosphere to be less than the evaporating surface. At one-hundred percent relative humidity, there is no more evaporation. The wind chill effect is one of the
Offering the unique ability to visually and audibly convey a story, films remain a cornerstone in modern society. Combined with a viewer’s desire to escape the everyday parameters of life, and the excitement of enthralling themselves deep into another world, many people enjoy what films stand to offer. With the rising popularity of films across the world, the amount of film makers increases every day. Many technological innovations mark the advancement of film making, but the essential process remains the same. Pre-production accounts for everything taken place before any shooting occurs, followed by the actual production of the film, post-production will then consist of piecing the film together, and finally the film must reach an audience. Each step of this process contributes to the final product, and does so in a unique right. The process of film making will now start chronologically, stemming from the idea of the story, producing that story into a film, editing that footage together, and finally delivering that story to its viewers.
As air humidity is in an instance of increasing, its ability to absorb water vapor decreases and evaporation rate slows down. For evaporation to undergo there must be a difference in humidity (Tenalem Ayenew and Tamiru Alemayehu, 2001; Fetter C.W, 1994).
Deposition occurs when a vapor is directly turned into a solid. Deposition is most frequently seen in frost or snowflakes. Although this process is relevant to the water cycle, it is not one that we experience as frequently as some of the other processes and is certainly not as distinct.