Examples of 'isotacticity' in a sentence
Meaning of "isotacticity"
Isotacticity - a term used in polymer chemistry to describe the regular arrangement of monomer units in a polymer chain
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- The state of being isotactic
- The extent to which a polymer is isotactic
How to use "isotacticity" in a sentence
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isotacticity
As isotacticity increases the xylene solubles decrease.
Meso pentad content is a measure of isotacticity.
An isotacticity target is established based upon production requirements.
Commercially useful products are of high molecular weight and isotacticity.
High isotacticity index polypropylene is the preferred polymer.
The invention is therefore useful in maintaining product isotacticity within preselected limits.
The isotacticity of the polymer was taken as the insoluble portion.
Particularly preferred metallocene catalyzed polypropylene polymer has medium range isotacticity.
Higher values for isotacticity are indicating higher degrees of crystallinity.
Such a molar ratio range is advantageous with regard to a high isotacticity of the obtained polymer.
The isotacticity of a polymer is important in determining its suitability for a given application.
This combination is indispensable for obtaining isotacticity and stereoregularity in the polymerization of propylene.
The isotacticity of the polymer can be controlled by appropriate selection of the isospecific metallocene.
The propylene polymer obtained according to the inventive process usually has a high degree of isotacticity.
Propylene polymers having high isotacticity are advantageous because of their high stiffness.
See also
Isotacticity can be determined through the use of NMR.
It has been demonstrated for polypropylene that TREF fractograms qualitatively reflect the distribution of isotacticity.
The higher the isotacticity the higher is the crystallinity of the polypropylene composition.
Finally, it has now been observed that high polymerization temperature increases isotacticity.
The isotacticity index corresponds to the percentage weight of the isotactic fraction of the polymer.
Difficulty in adjusting the isotacticity index down to low values ;.
As isotacticity increases in the polymer, the flexural modulus or stiffness increases.
In preferred embodiments of the invention, isotacticity control calculations will be done entirely within a computer.
The isotacticity is determined at the pentad level i.e. mmmm fraction of the pentad distribution.
More preferably, the interpolymer was not characterized by a high degree of either isotacticity or syndiotacticity.
However, this decrease in isotacticity is not significant in an industrial process.
More preferably, the interpolymer is not characterized by a high degree of either isotacticity or syndiotacticity.
The polymer 's isotacticity has been determined by means of a heptane extraction.
More preferably, the interpolymer was not characterized by a high degree of either isotacticity of syndictacticity.
The ( i ) means that complete isotacticity and syndiotacticity can be optionally controlled.
In its absence, low yields, low xylene insolubility and poor isotacticity are obtained.
The isotacticity is determined at the pentad level i.e. mmmm fraction ofthe pentad distribution.
This catalyst system gives good performances in terms of activity, isotacticity and xylene insolubility.
The above ( i ) means that complete isotacticity and syndiotacticity can be arbitrarily controlled.
This invention relates to a process for the controlled polymerization of stereospecific alpha-olefins having a preselected isotacticity.
For the determination of the isotacticity distribution, the TREF method can be applied.
Isotacticity index was measured by extracting with boiling n-heptane for 1 hr in Kumagawa glass extractor.
The diether-containing catalysts have super high activities and produce PP with high isotacticity.
The isotacticity and XS, respectively, were calculated by comparing the measured curve with a standard curve.
However, for film and fibre applications, lower isotacticity is desired.
Isotacticity of the polypropylene will generally be 80 percent or greater.
Difficulty in obtaining resins which have both a low isotacticity and good pourability ( problems of sticking ) ;.
Isotacticity index is n-heptane insoluble material of polymer calculated as w - %.
With transesterified high-yield ZN-catalysts, these temperatures will increase the isotacticity of the polymers.
By pentad isotacticity is meant the fraction of isotactic pentads ( mmmm ).
Thus, the lower the XS of an a-olefin polymer, the higher is its isotacticity.
A high isotacticity of greater than 90 is preferred and greater than 95 is most preferred.
Whereas the complex ( Ind ) 2ZrCl2 provides a polypropylene with a low isotacticity index I.
The isotacticity is determined by 13C-NMR analysis as described in the examples.
It is thus possible to adjust the isotacticity index from approximately 60 % to approximately 87 %.
