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Crystals are type of solid state bodies whose structural order are well defined and have a unique lattice structures. There is a perfect distance between the various layers in its structure. Crystallinity has big influence on the hardness, density of the body. Non- Crystalline substances are the ones who lack the structural order and do not posses the well defined lattice structure. They tend to have lower density and low melting point as there atoms are scattered. Crystals have high tensile strength while the non crystals are not.
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How Degree of polymerization affect to the crystallinity?
A higher degree of polymerization generally leads to higher crystallinity in polymers. Longer polymer chains can pack together more closely in an organized manner, increasing the likelihood of crystalline regions forming. This results in a higher degree of ordered molecular structure, leading to increased crystallinity in the polymer.
What are the characteristics of branched polymers and how do they differ from linear polymers?
Branched polymers have side chains branching off from the main polymer chain, giving them a more complex structure. This branching increases their flexibility and reduces their crystallinity compared to linear polymers, which have a straight chain structure. Branched polymers also have lower viscosity and higher elasticity than linear polymers.
How can polymers be modified to change their properties?
Polymers can be modified by adding additives, blending different polymers together, controlling the molecular weight, crosslinking, or changing the copolymer composition. These modifications can alter the mechanical properties, thermal stability, or chemical resistance of the polymer.
What are the factors that influence crystallinity?
In general it can be said that the most important factor affecting the crystallinity is the structure of the components used in polymer synthesis. If the polymer synthesized has a very symmetrical structure, then we can say that a highly crystalline material will form. The tacticity of the polymer is also important factor affecting the crystallinity. If the components are reacting in an ordered way, like syndiotactic PET, the material will be highly crystalline. But if the PET is atactic then it will be highly amorphous,even if the components of the polymer are the same.
What disadvantages does crystallinity in a polymer offer?
Crystallinity in a polymer can lead to decreased flexibility and impact resistance. It may also make the material more prone to stress cracking. Additionally, the presence of crystalline regions can affect the transparency and processability of the polymer.
How Degree of polymerization affect to the crystallinity?
A higher degree of polymerization generally leads to higher crystallinity in polymers. Longer polymer chains can pack together more closely in an organized manner, increasing the likelihood of crystalline regions forming. This results in a higher degree of ordered molecular structure, leading to increased crystallinity in the polymer.
In what four ways can polymers be modified to change there properties?
1. Chain length 2. Plasticizers 3. Cross linking 4. Crystallinity
What are the characteristics of branched polymers and how do they differ from linear polymers?
Branched polymers have side chains branching off from the main polymer chain, giving them a more complex structure. This branching increases their flexibility and reduces their crystallinity compared to linear polymers, which have a straight chain structure. Branched polymers also have lower viscosity and higher elasticity than linear polymers.
What is meant by water soluble polymers?
Water soluble polymers are polymers that will dissolve in water.
How is density influenced by crystallinity?
higher crystallinity in a polymer = lower density
Describe the following term in synthetic polymers syndiotactics?
In synthetic polymers, syndiotactic refers to a specific arrangement of monomer units in a polymer chain where the side groups alternate positions on opposite sides of the main chain. This arrangement can lead to unique material properties, such as increased stiffness and crystallinity, compared to atactic or isotactic polymers.
What describes a characteristic of branched polymers?
Branched polymers have side chains or branches extending from the main polymer chain, giving them a more complex and three-dimensional structure. This branching can affect the physical properties of the polymer, such as its flexibility, crystallinity, and viscosity. Branched polymers often exhibit different properties compared to their linear counterparts, making them useful in various applications, such as in adhesives and viscosity modifiers.
What structural characteristics of polymers would result in a relatively high melting point?
High polarity would give higher crystallinity and thus higher melting point. High degrees of cross-linking will mean the polymer may not even melt but char.
How can polymers be modified to change their properties?
Polymers can be modified by adding additives, blending different polymers together, controlling the molecular weight, crosslinking, or changing the copolymer composition. These modifications can alter the mechanical properties, thermal stability, or chemical resistance of the polymer.
How is the degree of crystallinity measured with by x-ray diffraction and differential scanning calorimetry?
The degree of crystallinity can be measured using X-ray diffraction (XRD) by analyzing the intensity and position of diffraction peaks; a higher intensity indicates greater crystallinity. In differential scanning calorimetry (DSC), crystallinity is inferred from the melting temperature and the enthalpy of fusion; the presence of sharp melting peaks and higher enthalpy values suggests a higher degree of crystallinity. Combining both techniques provides a comprehensive understanding of a material's crystalline structure.
What is the crystallinity of polypropllyne fiber?
The crystallinity of polypropylene fiber typically ranges from 50% to 70%. This high degree of crystallinity contributes to its strength, durability, and resistance to chemicals and moisture. The crystalline regions provide structural integrity, while the amorphous regions allow for flexibility and comfort in applications like textiles. Overall, the balance of crystallinity in polypropylene fibers plays a crucial role in determining their physical properties and performance.
How do you calculate crystallinity by XRD?
Crystallinity can be calculated by X-ray diffraction (XRD) by analyzing the intensity of the diffraction peaks in the XRD pattern. The degree of crystallinity is typically determined by comparing the area under the crystalline peaks to the total area under both crystalline and amorphous peaks. A common method involves using the formula: Degree of Crystallinity (%) = (Area of Crystalline Peaks / (Area of Crystalline Peaks + Area of Amorphous Peaks)) × 100. This provides a quantitative measure of the crystalline content in a sample.
