Raman Spectroscopic Analyses of Structure–Mechanical Properties Relationship of Crystalline Polyolefin Materials

Abstract

Raman spectroscopy is a vibrational spectroscopic technique that is widely used for analyses of the chemical structures and morphologies of polymeric materials. The peak position and peak area of each Raman band are influenced by microscopic deformations of molecular chain e.g. load-sharing, orientation, and conformational state. In particular, Raman spectroscopic analysis has been used to investigate the structure-mechanical properties relationship of semi-crystalline polyolefins (POs) because the C-C stretching mode, which is the main chain vibration of POs, is strongly Raman-active. The present review summarizes recent Raman spectroscopic analyses of the structure-mechanical properties relationship of POs.

Rheo-Raman Spectroscopic Study of Microscopic Deformation Behavior of Low- and High-Density Polyethylene Solids under Uniaxial Deformation

“…Because the 〈P 2 〉-〈P 4 〉 line of LDPE coincided with the most-probable 〈P 2 〉-〈P 4 〉 line of the uniaxial orientation, the crystalline chains of LDPE were uniaxially oriented into the stretching direction. On the other hand, the 〈P 2 〉-〈P 4 〉 line for HDPE showed a negative deviation from the most-probable uniaxial ume effects of lamellar crystalline structure 23,24,28,48) .…”

“…It is worth noting that the principal axis of the Raman tensor for the 1130 cm −1 band coincides with the molecular chain axis, suggesting that no calibration is required to correct for the angle difference between the molecular chain axis and the Raman tensor's principal axis 20) . In this study, the values of 〈P 2 〉 and 〈P 4 〉 were calculated using the polarized intensity of the 1130 cm −1 band, based on the depol constant method proposed by Frisk et al 23,41) .…”

“…The Thus, the Raman spectroscopy has been used to detect the load sharing and molecular orientation of main chains of PE 19,20) . A rheo-Raman spectroscopic system that combines a Raman spectroscopy device and a tensile machine has been developed to simultaneously evaluate microscopic deformation behaviors and macroscopic mechanical responses [21][22][23] .…”

Direct Observation of the Effect of a High-Molecular-Weight Component on the Deformation Behavior of Polyethylene Solids Using the Rheo-Raman Spectroscopic Technique

“…An increase in R suggests a high degree of molecular orientation in the stretching direction. Moreover, R corresponds to the orientation of the crystalline chains because both Raman bands are assigned to the molecular chains included in the crystal structure. , In the present study, the values of R for hPE and dPE were calculated from R h = I 1130 / I 1063 and R d = I 1150 / I 1063 , respectively, to evaluate the orientation behavior of hPE and dPE chains. It should be noted that the intensities of both Raman bands at 1130 and 1150 cm –1 increased by stretching, although the intensity of the Raman band at 1063 cm –1 was almost unchanged as shown in Figure S1 in the Supporting Information.…”

Perspectives on Polyolefin Catalysis in Microfluidics for High-Throughput Screening: A Minireview

“…32−34 Maintaining uniform conditions throughout the reactor is easy, providing precise parameters control for challenging chemistries and enhanced safety for toxic, fast, and exothermic reactions. Easy scale-up through numbering up in parallel for meeting the production demands with the same performance obtained in analysis of copolymers for chemical composition and molar mass distribution Fourier transform infrared spectroscopy 23 analysis of copolymers for chemical composition and molar mass distribution crystallization analysis fractionation 24 short chain branching in LLDPE olefin blends pyrolysis gas chromatography and mass spectrometry 25 additives in polyolefin Raman spectroscopy 26 structure−property relationship of semicrystalline polyolefins near infrared spectroscopy 27 composition of α-olefin copolymers deuterium labeling 28 chain-shuttling analysis the laboratory significantly reduces the time from laboratory to commercial development. 35 Ever rising demand for polymers with tailored properties for specific applications makes microfluidics for polymerization a suitable option.…”