Transition regions and surface melting in partially crystalline polyethylene: A raman spectroscopic study

Abstract

Structures of semi crystalline high‐molecular weight polyethylene and their changes with temperature were studied by analysis of Raman spectra. Decomposition of spectra into contributions of an orthorhombic crystalline phase, a meltlike phase, and two kinds of transition regions yields the respective mass fractions. The results of temperature dependent measurements is indicative of a largely reversible surface melting process, the transition regions being located at the crystal surfaces. As‐polymerized samples show a large fraction of the intermediate phase. Annealing leads to a reduction of this phase. © 1993 John Wiley & Sons, Inc.

Effect of weakly interacting nanofiller on the morphology and viscoelastic response of polyolefins

“…In the temperature range T g \ T \ T m , the chains in the amorphous region became mobile as revealed from the NMR or Raman spectra [15][16][17][18]. The amount of mobile phase is, in this case, much lower than the amount of the overall amorphous phase suggesting that some chains or their portions form an interphase in vicinity of the surface of crystalline lamellae.…”

“…In polymers such as PP and PE, the content of mobile amorphous phase content increases from 0 to 100 wt% nonlinearly in the temperature range from T g to T m . At room temperature, the mobile amorphous phase forms about 5-20 wt% in HDPE or PP [15][16][17][18]. Thus, in the case of nanocomposite with polyolefin matrix, the contribution of chain immobilization to the reinforcement should be proportional to the mobile amorphous phase content.…”

A Raman Spectroscopic Method of Evaluating Fat Crystalline States and Its Application in Detecting Pork Fat

“…Although the values of αC and Ctrans show similar dependencies on temperature and time, a considerable difference is seen between the crystallinity that is ultimately reached; 48% for αC and 35% for Ctrans. The difference of 13% can be attributed to the transition region adjacent to the crystallites (Mutter et al 1993). …”

“…Bands at 1297 and 1305 cm -1 were identified as originating from the crystalline and melt phases, respectively (Mutter et al 1993, Strobl & Hagedorn 1978. The sum of the integrated intensities of these two bands (I1297+I1305) that corresponds to the mass of all the methylene groups was found to be independent of temperature (Mutter et al 1993, Strobl & Hagedorn 1978, so the total intensity of both bands was adopted as an internal intensity standard in the denominator. Essentially, the same indicator was used to evaluate the crystallinity of such polymethylene systems as n-alkanes (Orendorff et al 2002), polyethylene (Takahashi et al 2010), and fatty acids (Kaneko et al 1994).…”

“…The factor of (1/0.493) is the experimentally acquired intensity correction coefficient for the 1418-cm -1 band relative to the internal intensity standard (I1297+I1305) (Mutter et al 1993, Strobl & Hagedorn 1978.…”