Deconvolution Protocols for Melt Crystallization Peaks in Recyclate Blends
Deconvolution of DSC melt crystallization peaks isolates PE and PP fractions in recyclates to verify composition before compounding.
Voigt Profile
Meaning
Mathematical convolution represents the combined influence of two distinct physical broadening mechanisms on a spectral line shape. A voigt profile arises when a gaussian distribution, originating from random thermal motion, undergoes convolution with a lorentzian distribution caused by finite lifetime effects or pressure collisions. This hybrid function enables technicians to distinguish between homogenous and inhomogenous widening within high resolution analytical data.
Polymer Analysis
Spectroscopic methods identify molecular chain architectures by measuring the energy absorbed during light interaction with chemical bonds. The voigt profile clarifies the underlying distribution of chain segments in crystalline and amorphous regions by separating temperature dependent broadening from lifetime limited excitation states. Accurate resolution of these curves ensures that the calculated modulus and degree of polymer orientation align with laboratory observations.
Process Influence
Deviations in a production environment force the spectral line to shift or broaden beyond its nominal limits. Excessive melt temperatures during extrusion widen the gaussian component, whereas high concentration additives increase pressure related lorentzian broadening. Moulders track the voigt profile to detect variations in internal stress distributions that indicate an unstable cooling rate within the tool.
Cost Impact
Computational resources required for fitting these complex functions demand significant time during quality control cycles. Engineers incur higher costs when the profile fitting algorithm fails to converge due to excessive noise or poorly calibrated sensors in the optical path. High precision equipment reduces the uncertainty in these calculations, which prevents the costly rejection of batches that possess adequate physical properties despite noisy signal signatures.