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How do environmental Changes Affect the Strength of different types of adhesives? Word Count: 3945 Abstract This essay explores the application and durability of different types of adhesives through the question How do environmental changes affect the strength of an adhesive? The main adhesive molecules that were investigated in this experiment were Polyvinyl Acetate and Polypropylene because they are the main active ingredient and most widely used in glue manufacturing. They comprise all of the wood glues and contact glues respectively and their application is immense.

The experiment consisted of gluing identical wood pieces together and then putting them for ours into extreme temperatures of CHIC and -ICC to see how they will react and how their adhesive properties changed. After this the wood sticks were separated using a force meter and the surface area of the glue stain after the separation was measured. The observed force applied against the surface area of the glue after the separation were plotted on a graph to examine the strength of the glue. Conclusively, the results of the experiment indicated several concepts.

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Primarily the experiment proved hat there is a directly proportional relationship between the surface area and the strength Of the glue, consecutively the experiment showed that the strength of an adhesive is determined by not only the chemical bonding but also by the mechanical bonding of the comprising molecules, so different changes in the external environment affect the adhesive molecules differently, hence answering the Research Question. The limitations to this experiment are that environmental changes consist of not only changes in the temperature but also change in humidity, exposure to LIVE light etc. ND the experiment was mainly focused on one type of environmental change – temperature. [270 Words] Contents: I. Introduction and purpose a. Polypropylene b. Polyvinyl acetate c. Ethyl congratulate d. Further Explanation I. Investigation a. Set up Preparation Of samples to test c. Analytical Techniques I. Explanation Preparation of samples iii. Analytical Methods Ill. Experimenting IV. Conclusion a. Reliability of the results b. Related questions c. Further Investigation V. Evaluation VI. Bibliography 1. Introduction and purpose: Any type of adhesive has the properties of adhesion and cohesion.

The ability of the glue to stick to surfaces and also to stick to itself determines its strength and quality. Generally there is no universally accepted theory of what happens when two objects stick together and researchers are still investigating the means by which the bond is formed. However for the purpose of this paper adhesion will be considered under two levels: mechanical level, and molecular level. Molecular level considers presence of van deer Walls forces and Hydrogen bonding since there is no significant chemical reaction in glue to form any other bonding such as covalent bonding r ionic bonding.

For the van deer Walls forces to be effective there has to be a separation between the surfaces of just a little over I. Ox -10 meters and the maximum surface area that is possible to be in contact. Van deer Walls forces are relatively weak forces compared to covalent bonding and ionic bonding, and they attribute to the adhesion of two objects just as much as the Hydrogen bonding does, however why two objects stick better when their surfaces are rougher could be explained by the idea that there is also something happening mechanically.

Mechanical bonding occurs when the adhesive or the glue goes into the little microscopic imperfections of the objects, fills these gaps and as it hardens it forms mechanical bond. The mechanical bonds are a result of the molecular structure of the substances which means that there is somehow a conflict between this type of bond and van deer walls forces since the scale is beyond the length of these forces. I An adhesive is likely to be working with both and this paper will consider equally in the further analysis 1. Polypropylene is a family of synthetic rubbers which is produced by the popularization of chlorine The modern chlorine process is based on he conversion of butadiene into the chlorine monomer (2- chlorination-l ,3). With the aid of free radical initiators, chlorine in the form of an aqueous emulsion is converted into honeymooners or, in the presence of co-monomers, into copolymers. Polypropylene in raw form is widely used as the main adhesive substance in contact adhesives. 1 It provides very high bond strength through diffusion.

An important property of polypropylene is its polarity which allows the substance to be dissolved in wide variety if polar solvents thus allowing it to produce a stable solution for glue. Figure 1 directly used from Figure 1 directly used from womb. CLC. Was 1. 2 Polyvinyl acetate Polyvinyl acetate is a thermoplastic polymer which means that it has a high melting temperature and is elastic and flexible at room temperature.. The manufacturing process involves free radical popularization of vinyl acetate which occurs as the monomer molecule of vinyl acetate is added to water.

The final product is milky white in color and is then instantly processed as a polyvinyl acetate. PA is a synthetic resin polymer, it has non polar nature and is insoluble in water and other polar elevens however it could be dissolved in some alcohols. PA is widely used in adhesives after being converted into polyvinyl alcohol. The process goes through partial hydrolysis and makes the PA(alcohol) soluble in water. PA is very easy to handle due to its properties and solubility in water.

It works best on porous materials such as wood which proves that the adhesive has a stronger mechanical bond. 34 1. 3 Ethyl congratulate Figure 2 Directly used from Wisped image bases CA (CHIN) is a clear liquid that is clear in color and strong acrid smell. It forms a solid polymer when reacting with water. Ethyl congratulate is prepared from condensation of allayed with ethyl concatenate. The reaction is exothermic and thermally cracked- or also broken down into simple molecule it gives the monomer.

It is used as very quickly drying glue and is the most common found in the world. 6 The molecule is not polar and is not dissolved in water however it is soluble in acetone and depositories when heated. 7 1. 4 Further explanation The three types of molecules are the main ingredient for most of the common found glues on the market. They all have different properties and work under different conditions. They all share same properties of adhesion and cohesion. If used under the instructed condition they will serve properly as adhesives.

They are used widely as repair and building materials and their applicability is limitless, which brings up the question how reliable they are for the purpose that they serve. Or in other words: How do the changes in the environment affect the strength of different types of adhesives? 1. 5 The purpose behind this investigation: Penthouse each and every adhesive goes with its purpose in the big building industry every finished project, being a building, a monument or even an object would have different bonds with different glue types however as a finished project it will experience the same condition on every part and corner of it.

I consider it important to have the ability to predict under which conditions which joint has to be checked for maintenance especially when it comes to buildings for example. This paper and investigation would give a basic notation of the specific effects that the environment has on different types of adhesives. Predictions: Polypropylene in theory should be the one able to withstand most since it experiences great adhesive and cohesive properties. The molecule has strong Van deer Walls forces and with its natural rubber-like character it should be able to undergo manipulation.

However the molecule is not very resistive and relies on a lot of external support to form a strong bond. So based upon assumptions polypropylene is favorable to come out to be the strongest most resistive adhesive. 2. Investigation. To investigate the strength of different adhesives under different environment there are 3 processes that must be implemented: 1 . Setting up extreme environment conditions such as high moisture, high temperature and freezing temperature. 2. Preparation of samples to test 3. Analytical techniques 2. 3. In order to simulate extreme environments an insulate box was made out of Styrofoam. The box is built in such way that the walls would be thick enough so that no external factors can affect the probes. Also two thermometers are included in order to keep the desired temperature and a moisture meter to follow the air condition. Temperature is very important to be controlled and kept constantly over the drying period of the adhesives. In order to keep a very low temperature in the box ice containers will be periodically switched in order to maintain a low temperature.

To create a high temperature a radiator will be inserted and heated. For the moisturizer air (still in progress) 2. 3. 2 Preparation Of samples to test. For the all three types of glue to be tested 30 wooden pairs of sticks Will be glued together with same amount of glue each time. The amount will be controlled based on surface area not quantity because surface area is of higher priority when it comes to sticking objects(l . 2) Extra high attention will be paid to the instructions of each type of glue to ensure the best possible gluing conditions for each probe.

A template of the surface area that the glue as to cover is specifically measured so that the bond would be weaker than the strength of the wooden sticks. The probes will be immediately put under the specific condition for a period of 24 hours to dry out. Since some adhesives require pressure to be applied all of the probes will receive equal pressure over the drying period. 2. B Analytical methods Bond strength has to be determined in the overall experiment so it is important to have a proper way of maintaining same comparison. The following methods were developed of which the best was chosen. . Using force meter to pull down glued objects. The method involves applying measured force until the two objects snap 2. Increasing the distance between the two objects until the bond is broken. This involves distances of very small scale since bonds are microscopic so the method is eliminated. 3. Applying sideways force. This was eliminated due to the higher force needed to break the bond. Some of the wooden sticks might not be able to withstand this force. Out of the three methods the best chosen was to apply measured force downwards until the snap.

It would allow to produce an analyzable data and would give instance for a good conclusion. Wooden planks are used in overall reasons: 1 . Wood is a porous material that has a relative high strength even if not thick enough. Since this paper is testing both the mechanical bond and van deer Walls forces all conditions must be applied. 2. Wood is also most commonly used building material so all the three types of glue should in theory be well working with it. 3. Wood will be able to withstand all of the changes in the environment such as the temperature and moisture.

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