Lab 7 - lab coursework PDF

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Lab #7 Foaming Processing 04/12/2017 MMET 281 Section 502 Christos Kitras 224002011

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Introduction Foam materials can be made of both thermoset and thermoplastic polymers and have many applications. The objectives of this lab were to observe and practice elementary foam practices, and to gain an understanding of the applications that these foam processes are involved in.

Experimental methods Experimental procedures and materials In this lab we produced foamed parts using a low pressure molding process. A two part urethane foam was used at a 37% part A to 63% part B by weight. We then casted a large football using a specific predetermined mix ratio.

Results The large football weighed 64 grams using 28 grams of part A of the two part urethane mix and 48 grams of part B of the urethane mix. This means that 12 grams of scrap was produced. The football was not completely filled out in the mold but turned out mostly full as is shown in the image below.

Write Up Questions 1. Foamed polymers and parts are advantageous in many applications both industrial and commercial. These include thermal insulation, low weight to high volume material, floatation devices, cushions, and sound insulation. Another advantage is the fact that you can turn a relatively small amount of plastic into a large volume material making it cost effective. 2. Open cell materials are foamed parts that have cells that are interconnected and have openings between the cells. These are used for insulation and applications where a high volume to weight is required such as panel insulation. On the other hand, closed cell materials have individual cells that are separated and discrete from one another. These are used for applications such as sealing and preventing the penetration of air and moisture. 3. Casting is advantageous over other manufacturing processes of foamed parts in that it may be used to mix resins and form a cellular structure in a simple process that can produce large slabs and blocks to be machined into other parts, as well as large parts extruded such as cushions or floatation devices. Similarly, there is a continuous process for mass production.

Design Question In order to make a football that meets design specifications, I would cast a foam football out of rigid foam resin dyed white and then paint half of the football maroon. The polymer will be dense because of the high volume of initial resin used compared to the relatively small football mold which will contain the polymer until it hardens, improving density and allowing for weight of the ball to be increased. This will help with the lightness issues of the ball being blown away. Finally, I would apply a coating of closed cell polymer to the ball to make it impermeable to foreign attacks and more durable....