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The amount of strain in the stable neck is called the natural draw ratio [6] because it is determined by the material's hardening characteristics, not the amount of drawing imposed on the material. Ductile polymers often exhibit stable necks because molecular orientation provides a mechanism for hardening that predominates at large strains. [7]
Draw resonance has not been found to be a function of the flow rate, however. A polymer melt approaching a Newtonian fluid such as PET can have a drawdown ratio of around 20, whereas highly shear thinning and viscoelastic polymer melts such as polyethylene, polystyrene, and polypropylene may have critical drawdown ratios as low as 3.
Branch point in a polymer. Polymer architecture in polymer science relates to the way branching leads to a deviation from a strictly linear polymer chain. [1] Branching may occur randomly or reactions may be designed so that specific architectures are targeted. [1] It is an important microstructural feature.
If both values are near 0, the monomers are unable to homopolymerize. Each can add only the other resulting in an alternating polymer . For example, the copolymerization of maleic anhydride and styrene has reactivity ratios r 1 {\displaystyle r_{1}\,} = 0.01 for maleic anhydride and r 2 {\displaystyle r_{2}} = 0.02 for styrene. [ 7 ]
A uniform polymer (often referred to as a monodisperse polymer) is composed of molecules of the same mass. [5] Nearly all natural polymers are uniform. [6] Synthetic near-uniform polymer chains can be made by processes such as anionic polymerization, a method using an anionic catalyst to produce chains that are similar in length.
[1] [2] [4] One added benefits of using polymers prepared by interfacial polymerization is that several properties, such as pore size and interconnectivity, can be fined-tuned to create a more ideal product for specific applications. [1] [4] [5] For example, synthesizing a polymer with a pore size somewhere between the molecular size of ...
Poisson's ratio of a material defines the ratio of transverse strain (x direction) to the axial strain (y direction)In materials science and solid mechanics, Poisson's ratio (symbol: ν ()) is a measure of the Poisson effect, the deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading.
The synthesis and processing of polyacetylene films affects the properties. Increasing the catalyst ratio creates thicker films with a greater draw ratio, allowing them to be stretched further. [8] Lower catalyst loadings leads to the formation of dark red gels, which can be converted to films by cutting and pressing between glass plates. [20]