Chemometric Methods for Estimating the Strain Hardening Modulus in Polyethylene Resins.

The feasibility of using multiway or N-way partial least square (NPLS) methods to estimate physical properties of 1-butene and 1-hexene polyethylene (PE) copolymers directly from multidimensional data obtained from size exclusion chromatography coupled to a Fourier transform infrared detector (SEC FT-IR) was explored. Digital sample sets of horizontal slices (slabs) of two-dimensional data simulating the molecular weight distribution and the corresponding orthogonal FT-IR spectra were correlated to a particular Y-block response using NPLS. The NPLS results were compared to those obtained through separate estimations using various algorithms and exploratory response surface methods. The estimated strain hardening modulus () for bimodal PE-like digital structures could adequately be modeled using both the linear response surface method (RSM) and NPLS. Although different input values were used, the predicted values for  by NPLS was found to mirror both the analytical results and the expected structural effects obtained using linear RSM models.