Phase Behavior : Melting Point

In the modern world, it is near impossible to live in an environment where one is not exposed and reliant upon the use of polymers. From credit cards to nappies; plastic bottles to prescription glasses, the applications of polymers encompass an endless range of everyday necessities. However, the significance of synthetic polymers was not universally recognised until its initial introduction as polyethylene during World War II. During the combat, they served as a critical material for insulated radar electronics (ACC, 2005).

A basic understanding of polymerization processes is important not only because polymerization affects structure, and hence properties, but also because some processing routes can convert monomers directly to a finished shape. They offer manufacturing industry considerable benefits both in direct and indirect costs. An extra dimension to polymer structure is added by the possibilities of copolymerization, where two or more different monomers a re polymerized together. In one sense it is comparable to alloying different metals to produce an appropriate balance of properties in the final product. Two groups of polymerization are normally acclaimed. In condensation polymerization, each step of the process is accompanied by formation of a molecule of some simple compound, often water ( ). In addition polymerization, monomers react to from a polymer without the formation of by-products. Addition polymerization usually are carried out in the presence of catalysts, which in certain cases exert control over structural details that have important effects on the properties of the polymer. Linear polymers, which are composed of chainlike molecules, may be viscous liquids or solids with varying degrees of crystallinity; a number of them can

Macromolecules have a large covalent structures which contain non-metal atoms, they are joined to contiguous atoms by covalent bonds. Substances that have giant covalent structures have high melting points due to a lot of strong covalent bonds that must be broken.

Melting Point, Freezing Point, Boiling Point. http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/melting.php. 3) Lide, David R. CRC Handbook of Chemistry and Physics: A Ready-reference Book of Chemical and Physical Data. Boca Raton, FL: CRC, 1994.

The melting point of a chemical is a physical property inherent to that substance. The chemical changes from a solid to a liquid state, but the composition remains the same. It can be used to determine the identity of an unknown substance. The purpose of this experiment was to discover the identity of an unknown chemical by determining its melting point.

More recently, distinctions between states have been based on differences in molecular interrelationships. Solid is the state in which intermolecular attractions keep the molecules in fixed spatial relationships. Liquid is the state in which

When the material gets hotter the molecules vibrate more intensely. When the molecules bump into each other the material will tend to expand. When the temperature gets colder the material will tend to get together like get smaller or scrunch up. Rubber bands have different molecules than other materials. Their molecules are like very long chains.

This mechanism is based on assumption that the polymer forms a continuous phase in which the plasticizer & other additives are homogeneously dispersed. When polymer film is formed, it contains molecular sized openings between crosslinked chains of polymer. Plasticizer & other additives affects wetting of these openings as well as interchain dimensions by changing the crosslinking properties of polymer chains which are critical for diffusion of drug. Mostly, drug molecules diffuse through these openings in a process known as hindered molecular diffusion. It is an activated process wherein thermal fluctuations of chain segments

Since glaciers are melting, many organisms are being affected. Since glaciers are melting, the habitat of polar bears, walruses, arctic foxes, and other arctic animals are being destroyed, leading to theses animals’ extinction. Glacial melting leads to a rise in sea levels, which gives land animals less land to live on. Glacial melting has been going on forever because glaciers are always building up and retreating, but glacial melting started to get worse around the 1800s, when the production of trains and factories was big. Glacial melting affects arctic animals, sea levels, and potable, drinkable, water.

Polymer composites are the blend of polymers and filler materials. Disadvantages of polymers such as low mechanical and electronic properties can be improved through reinforcing with much stronger and highly conducting filler materials. Thus, fabricating polymer composites is of mutual benefit to both polymers and fillers. Furthermore, advanced-desired applications can be tailor-made. Also, compared to polymer micro/nanocomposites, polymer nanocomposites show much more improved properties such as extremely smooth finishing, excellent mechanical and electrical properties at lower loadings as low as 0.025 volume % (Schandler, Brinson & Sawyer 2007). In the current chapter, both polymer microcomposites and polymer nanocomposites are briefly discussed.

I was instructed to record a melting point range for each compound, rather than a single temperature melting point. The reason for this instruction is that polymers and unpure substance melt over a range of several degrees. Based on the melting point ranges for both substances, it is difficult to differentiate the two based on its melting point data alone. The ranges of the substances are close enough to one another that one could argue for experimental error when presenting the data as a solo identifying property.

Critical temperature: The temperature at which the resistance of a material suddenly drops to zero is termed as critical or transition temperature.

Thermal energy storage (TES) system store excess thermal energy with different applications and materials and release it for later use. [1] For instance, TES systems is an available means to balanced energy demand between day time peak hours and night time lower usage of energy. Specially, with the applications such like solar collectors, thermal energy storage system can be used to collect summer heat and storage for winter space heating; and summer space cooling like wise. [2] Similar with other energy storage systems, TES systems provide a possibility to overcome the mismatch between energy generated and usage, which is an important environmental-friendly approach to solve the problems of present energy usage and carbon dioxide emissions. [3] Fig. 1 below shows about areas of research in thermal storage systems.

Commonly, it is simple to blend of similar polarities and solubility of rubber and plastic to make a valuable thermoplastic elastomer, for example PP/ethylene-propylene-diene copolymer EPDM, epoxidized natural rubber (ENR) with polyvinyl chloride (PVC), PVC/NBR) and nylon/NBR. However, it is obscure to fabricate a TPE via an elastomer and plastic comprising different polarities as well as solubility. This is owing to being of large interfacial tension between these two polymers. This intricacy can be solved by the utilize of a compatibilizer to get better interfacial relation between two phases [1].

Breaking the limits of picosecond temporal resolution (600 fs) in electron diffraction measurements were first reported in Siwick et al. [15]. This gave the access to the atomic motion in the photo-induced solid-liquid phase transition (melting) process of Aluminum. In this study, the long-order change traced as a function of time. The 20-nm-thick Al sample was excited by a laser pulse fluence of 70 mJ/cm2. The long-range order (present in the crystalline phase) disappear and a short-range atomic correlation (present in the liquid phase) were emerged which is a clear indication of a complete phase translon process within 3.5 ps (Fig. 7a).