Comparing polarized Raman spectroscopy and birefringence as probes of molecular scale alignment in 3D printed thermoplastics.
MRS Commun
; 11(2): 157-167, 2021 Apr 09.
Article
em En
| MEDLINE
| ID: mdl-38482539
ABSTRACT
Polymer chain orientation is crucial to understanding the polymer dynamics at interfaces formed during thermoplastic material extrusion additive manufacturing. The flow field and rapid cooling produced during material extrusion can result in chains which are oriented and stretched, which has implications for interdiffusion and crystallization. Polarized Raman spectroscopy offers a non-destructive and surface sensitive method to quantify chain orientation. To study orientation and alignment of chains in 3D printed polycarbonate filaments, we used a combination of polarized Raman spectroscopy and birefringence (Δn) measurements. By changing the orientation of the sample with respect to polarization of incident radiation, we probe changes in the ratio between orientation-dependent vibration modes and orientation-independent modes. We used principal component analysis (PCA) and partial least squares (PLS) regression to develop correlations for birefringence and Raman measurements in samples that were pulled at different draw ratios (DRs). PCA was used to differentiate between orientation-dependent and orientation-independent modes, while PLS regression was used to calculate birefringence from Raman measurements of 3D printed samples. Birefringence measurements were compared to the polycarbonate intrinsic birefringence of 0.2, to estimate the degree of orientation. We find that measured values of birefringence underestimate orientation compared to Raman measurements.
Texto completo:
1
Base de dados:
MEDLINE
Idioma:
En
Revista:
MRS Commun
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Estados Unidos