In situ confocal micro‐Raman spectroscopic investigation of rearrangement kinetics and phase evolution of UHMWPE during annealing

Abstract

Ultrahigh molecular weight polyethylene was investigated using in situ confocal micro-Raman spectroscopy during annealing at 110.0°C. Based on the Raman spectra, crystalline, amorphous, and all-trans noncrystalline fractions were recognized to evaluate rearrangement kinetics during isothermal annealing at 110.0°C and phase evolution during cooling from 110.0 to 30.0°C. For the crystalline fraction, a substantial increase from 0.600 ± 0.001 to 0.639 ± 0.008 was observed during the first 24.2 min of annealing; a very gradual increase from 0.639 ± 0.001 to 0.679 ± 0.001 occurred during the following 114.6 min. For the amorphous phase fraction, conversely, a sharp decrease from 0.240 ± 0.000 to 0.213 ± 0.004 was exhibited during the first 24.2 min of annealing, and then, a flat decrease happened from 0.213 ± 0.004 to 0.192 ± 0.001 as time expanded to 138.8 min. For the all-tans noncrystalline fraction, a gradual decrease was shown from 0.160 ± 0.000 at 0.0 min to 0.128 ± 0.001 at 138.8 min. The rearrangement rate constant K was obtained to be 0.632 by an Avrami equation. During cooling from 110.0 to 30.0°C, there were two phase evolution regions: region 1 from 110.0 to 90.0°C and region 2 from 90.0 to 30.0°C. The crystal lamella thickened faster in region 1 than in region 2. The amorphous layer continually decreased in content in the combined region of 1 and 2. The all-trans noncrystalline phase obviously decreased in region 1 and then almost maintained a constant level in region 2.

Vibrational Analysis of Semicrystalline Polyethylene Using Molecular Dynamics Simulation

“…In a follow-up to Naylor et al, Mandelkern and Alamo 34 commented that estimates of interfacial composition using the method of Strobl and Hagedorn were consistent with estimates from different experimental techniques. Even nearly four decades later, the method of Strobl and Hagedorn is still used to characterize the domain compositions of PE 5,35,36 and has been extended to additional SC polymers. 37 In this work, we investigate the dynamic heterogeneities associated with the vibrational motions within SCPE using molecular dynamics (MD) simulations.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part X

“…He and Lu carried out an in situ confocal micro‐Raman spectroscopic investigation of rearrangement kinetics and phase evolution of ultra‐high molecular weight polyethylene during annealing . Liszka and co‐workers carried out a Raman micro‐spectroscopy investigation of quantitative thickness measurements of nanometer thin polymer films.…”

“…[126] Linear chains and polymers He and Lu carried out an in situ confocal micro-Raman spectroscopic investigation of rearrangement kinetics and phase evolution of ultra-high molecular weight polyethylene during annealing. [127] Liszka and co-workers carried out a Raman micro-spectroscopy investigation of quantitative thickness measurements of nanometer thin polymer films. The results illustrate the ability of far-field Raman microscopy as a sensitive method to quantitatively determine the thickness of thin films down to the nanometer range.…”