Unable to display preview. Download preview PDF. Skip to main content. This service is more advanced with JavaScript available. Advertisement Hide. This process is experimental and the keywords may be updated as the learning algorithm improves. Instead, they reach a range of temperatures over which the material becomes less glassy and more rubber-like or vice versa. The glass transition temperature of a specific polymer may be listed as a single temperature, but this number is a representative value representing a range of temperatures.
To explain glass transition temperature in terms of molecular motion, we would say that, at temperatures below T g , the amorphous polymer chains cannot rotate or move in space the cooked spaghetti is frozen and cannot move. This produces the glassy state, which is hard, rigid, and brittle. When the temperature rises above T g , the entangled chains can move small portions of the spaghetti noodles can move around. This produces a rubbery state, when an amorphous polymer is soft and flexible.
Although percent and 0 percent crystallinity are rare, some polymers fall close to either extreme. Those that tend toward high crystallinity are rigid, have high melting points, and are less affected by solvent penetration. Those that tend toward high amorphousness are softer, have glass transition temperatures , and are penetrated more by solvents than are their crystalline counterparts.
Here are some examples, along with their key properties:. To understand why, it helps to realize that polymers can have multiple configurations.
A polymer has a main backbone with small clusters of atoms, called pendant groups, coming off of the chain. If all of the pendant groups are on the same side of the chain, the polymer is isotactic. If the pendant groups come on alternating sides of the chain, the polymer is said to be syndiotactic.
If the pendant groups are on both sides, but in no particular order, the polymer is atactic. These structural differences can have a significant impact on the properties of a polymer. Many applications of polymers and polymer coatings need flexibility at low to ambient temperatures. Conversely, when hardness and rigidity are required, a polymer with greater crystallinity may be preferred. Mallard Creek Polymers specializes in the design and manufacturing of amorphous polymers.
We work with customers to understand their needs and to develop emulsion polymers that address those needs. Call us for more information. Back to Library. Polymer Morphology In polymer chemistry, morphology is a key factor in describing the distinction between amorphous and crystalline solids.
Contact us for more information. Back to Library. Glass Transition Temperature One of the most important characteristics of amorphous polymers is glass transition temperature T g. At the atomic level, we would see very little motion around the bonds holding the atoms together. Now we would see something a little different. And there would be significantly more motion around the atomic bonds. Amorphous vs. Crystalline Most amorphous polymers are not completely amorphous.
Characteristics of Amorphous Polymers The molecular structure of a polymer — and the degree of crystallinity — has a tremendous impact on its properties. Here are some of the common properties of amorphous polymers: They exhibit relatively low resistance to heat.
Because they have a randomly ordered molecular structure that lacks a sharp melting point, they soften gradually as the temperature rises. They are not prone to shrinkage as they cool. They are tough and brittle at low temperatures, but they lose their toughness quickly above their glass transition temperature and become malleable and prone to elongation.
Due to their deformability, they can bond well to substrates. They often need to be applied and dried above their glass transition temperature, or minimum film formation temperature MFFT to avoid defects in the final material. For example, if the drying temperature is below the MFFT, then a discontinuous film or powder compact may form. See our article on film formation to learn more.
Amorphous Polymer Specialists Mallard Creek Polymers specializes in the design and manufacturing of amorphous polymers. We've got you covered. Get in touch to talk with one of our chemists to find custom solution today. You may also interested in: Polymer Questions.
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