Investigation of melting behaviors and crystallinity of linear polyamide with high‐aliphatic content

Abstract

ABSTRACT:The melting behaviors and crystal structures of a long alkyl chain polyamide and nylon 18 18, were investigated under annealing and isothermal crystallization conditions. Nylon 18 18 showed multiple melting peaks in differential scanning calorimetry (DSC) thermograms depending on thermal history of the samples. The origin of the multiple melting peaks may be a result of a melting and recrystallization mechanism during DSC scans. Wide-angle X-ray diffraction patterns showed two new diffraction peaks, which appeared at 0.44 and 0.37 nm, and are characteristic peaks of a-form (triclinic structure) of even-even nylons with increasing annealing temperature. The intensities of these peaks increased, and they split further apart, with elevated annealing temperatures. The solid-state 15 N CP/MAS NMR spectra of the nylon 18 18 samples that had been quenched and annealed also confirmed the a-crystalline form. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: [92][93][94][95][96][97][98] 2012

Diamines for Polymer Materials via Direct Amination of Lipid‐ and Lignocellulose‐based Alcohols with NH3

“…[54] Stoichiometric amountso ft he diamine and the diacid were reactedi nt he initial presence of excesswater as ar eaction medium (Table 2). [54] Stoichiometric amountso ft he diamine and the diacid were reactedi nt he initial presence of excesswater as ar eaction medium (Table 2).…”

“…Melt-polycondensations were carriedo ut under elevated pressure in a2 5mLs tainless steel reactor. [54] Stoichiometric amountso ft he diamine and the diacid were reactedi nt he initial presence of excesswater as ar eaction medium (Table 2).…”

“…General procedure for the preparation of long-chain X,X polyamides: [54] Stoichiometric amounts of diamine and diacid (ca. 1g substrates) were weighed into a1 5mLg lass inlay and placed in a2 0mLa utoclave.…”

The Influence of Annealing Process on Crystallinity and Structural Properties of Cotton/Spandex Fabric

“…The results show that the untreated sample, which is the same as a semi crystalline polymer structure, presented some large and wide reflections due to its internal structure, and can be assigned according to the literature [17][18][19], with one significant peak appearing Figure 2, when the heat-setting condition surpassed C1, two peaks appeared that were (002) and (100). As the temperature increased, (002) peaks shifted from 19.58°t o 22.58°, then the (100) diffraction peaks enhance.…”

Fluidity improvement of semiaromatic polyamides: Modification with oligomers

“…Peaks were assigned according to lit. 42,43 Considering the low sensitivity of 13 C-NMR, terminal carboxylic acid group with higher concentration was chosen to be a reference to determine the concentration of phenyl groups deduced from benzoic acid. Terephthalic end groups (Tx) appeared at 133.27, 130.68, and 127.38 ppm, and benzoic end groups (Bx) appeared at 135.…”