Comparing polarized Raman spectroscopy and birefringence as probes of molecular scale alignment in 3D printed thermoplastics
Comparing polarized Raman spectroscopy and birefringence as probes of molecular scale alignment in 3D printed thermoplastics
复制标题
比较偏振拉曼光谱和双折射作为 3D 打印热塑性塑料中分子尺度排列的探针
作者：
N. Hassan;K. Migler;A. H. Hight Walker;Anthony P. Kotula;J. Seppala
聚合物链取向对于了解热塑性塑料挤出助剂制造过程中形成的界面上的聚合物动力学至关重要。在材料挤压过程中产生的流场和快速冷却会导致链条取向和拉伸，这对互扩散和结晶有影响。偏振拉曼光谱提供了一种非破坏性和表面敏感的方法来定量链的取向。为了研究3D打印聚碳酸酯长丝中链的取向和排列，我们使用了偏振拉曼光谱和双折射相结合的方法(ΔnDocumentClass[12pt]{Minimum}usepackage{amsath}usepackage{wa ysym}usepackage{amsfonts}usepackage{amssymb}usepackage{amsbsy}usepackage{mathrsfs}usepackage{upgreek}setlong{oddsidemarin}{-69pt}例如{Document}$$Delta n$$End{Document})。通过改变样品相对于入射辐射的偏振方向，我们研究了取向相关振动模和取向无关振动模之间的比率的变化。我们使用主成分分析(PCA)和偏最小二乘(PLS)回归建立了在不同拉伸比(DRS)下拉伸的样品的双折射和拉曼测量之间的关联。主成分分析被用来区分取向相关和取向无关模式，而偏最小二乘回归被用来从3D打印样品的拉曼测量中计算双折射。将双折射测量结果与聚碳酸酯的本征双折射0.2进行比较，以估计取向程度。我们发现，与拉曼测量相比，双折射的测量值低估了取向。
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 (Δndocumentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$Delta n$$end{document}) 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.
影响因子：
11
作者：
Fang, Lichen;Yan, Yishu;Kang, Sung Hoon
通讯作者：
Kang, Sung Hoon
影响因子：
11
作者：
Costanzo, Andrea;Spotorno, Roberto;McIlroy, Claire
通讯作者：
McIlroy, Claire