(181bt) Experimental Validation of Deconvolution Theory

justify;line-height:200%"> font-family:" times new roman>Experimental validation of deconvolution
theory

justify;line-height:200%">Raunil
Raj, Saeid Mehdiabadi, João B. P. Soares

justify;line-height:200%"> font-family:" times new roman>Abstract

Polyolefins
made from industrially important catalysts like Ziegler-Natta catalysts or
Phillips catalysts produce broad molecular weight distributions (MWD) with a polydispersity
index (PDI) more than 2, a deviation from the expected behavior from Flory’s
Distribution. Additionally, the chemical composition varies across the
molecular weight instead being constant. This behavior is attributed to the multi-site
nature of such catalysts. The catalysts are believed to have multiple sites and
the polymers produced from them, as a result, are an accumulation of polymers
made on each site type. Some new generation catalysts like metallocene and late
transition metal catalysts are known to produce polymers that have molecular
weight distribution, PDI, and chemical composition distribution (CCD) which can
be described by Flory and Stockmayer distributions.

An
estimate of the number and response of the sites in the multiple site catalyst can
be obtained via numerical techniques known as MWD and CCD deconvolution. Through
this approach, the hypothetical number of site types required to be assumed in
order to fully describe the molecular weight distribution and chemical composition
distribution of the polymers made by multiple site catalysts are estimated. This
very useful technique, however, is a theoretical way of understanding the
catalytic system and is still debated if it is a true representation.

justify;line-height:200%"> font-family:" times new roman>In the present work, the deconvolution techniques
were validated experimentally. Polymers were made with a commercial Zeigler
Natta catalyst, and MWD and CCD deconvolution were applied to get the theoretical
MWD and CCD of the polymers made on each site. Thereafter, those polymers with the
specific microstructure were made using single-site metallocene catalysts and
were blended in the proportion as described by deconvolution. The overall
microstructure of the blend was found to be nearly the same as the polymer
produced with multi-site Zeigler Natta catalyst.

justify;line-height:200%"> font-family:" times new roman> 

justify;line-height:200%"> font-family:" times new roman> 

200%">