Molecular weight distributions of linear polymers: Detailed analysis from GPC data

Abstract

The GPC method is used widely to measure molecular weights of linear polymers. High‐quality GPC data contains detailed information on many aspects of the polymer's molecular weight distribution (MWD). This information can be extracted from the data using computer analysis. Equations have been derived for the two simplest MWD functions in the GPC coordinates: the Flory function (one growing polymer chain produces one polymer molecule), and for the case when two polymer radicals combine into one polymer molecule. The equations were used to analyze MWD of two classes of polymers. The first class includes polymers with narrow MWD: polyethylene, ethylene‐propylene and ethylene‐hexene copolymers, syndiotactic polystyrene, and radical polystyrene. The second class includes polymers with broad MWD: ethylene copolymers and polypropylene produced with heterogeneous, Ti‐based catalysts. The examples demonstrate that the resolution of complex GPC curves into their constitutents serve as an important source of information about kinetics of polymerization reactions. © 1995 John Wiley & Sons, Inc.

Multiple active site Monte Carlo model for heterogeneous Ziegler‐Natta propylene polymerization

“…Corresponding GPC curves/data are obtained. However, the results obtained by extracting MWD information from the GPC curves according to Kission' approach 29 are similar. In our previous work, 25 we recorded the polymerization kinetic data under the same experimental conditions as those in this work except the atomic ratio of Si/Al.…”

“…In practice, Kission' s approach is the resolution of GPC curves using the Flory distribution equation. 29 This algorithm assumed that each site type produces a most-probable MWD,…”

“…A simple approach was developed by Kissin, 29 which provides a means to extract detailed MWD information from GPC data.…”

“…In addition, the number of the active site types of the CS-1 catalyst is obtained via the deconvolution of molecular weight distribution (MWD) described in the following section. 29 …”

Study on the microstructures of polypropylene synthesized by a novel MgCl2-supported and low Ti-loading Ziegler–Natta catalyst

“…It seemed that the MWD curve was piled up by MWD curves of polymers produced by different types of active centers (as shown in Fig. 1), which could be mathematically expressed as follows [31]:…”