{"title":"Study on the Brill transition of polyamide 6 with different crystal forms using low- and high-frequency Raman spectroscopy†","authors":"Jiacheng Gao and Harumi Sato","doi":"10.1039/D4RA08523J","DOIUrl":null,"url":null,"abstract":"<p >Polyamide 6 (PA6) in its α and γ-forms was studied from 30 to 220 °C using Raman spectroscopy in the low- and high-wavenumber regions. Quantum chemical calculations were employed to assist with band assignments. In the low-wavenumber region, a peak at approximately 100 cm<small><sup>−1</sup></small>, attributable to a mixed mode of methylene lateral motion and amide group stretching, was observed. Additionally, a new band at approximately 60 cm<small><sup>−1</sup></small> was observed and assigned to molecular chain torsions in the α-form. Both bands indicated that molecular chain rotation occurs prior to the Brill transition at approximately 130 °C. In the high-wavenumber region, bands at approximately 1126 cm<small><sup>−1</sup></small> and 1060 cm<small><sup>−1</sup></small> indicated a simultaneous weakening of C–C stretching modes in the <em>trans</em> conformation at the same temperature, consistent with observations in the low-wavenumber region.</p>","PeriodicalId":102,"journal":{"name":"RSC Advances","volume":" 3","pages":" 2224-2230"},"PeriodicalIF":3.9000,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11755107/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"RSC Advances","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2025/ra/d4ra08523j","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Polyamide 6 (PA6) in its α and γ-forms was studied from 30 to 220 °C using Raman spectroscopy in the low- and high-wavenumber regions. Quantum chemical calculations were employed to assist with band assignments. In the low-wavenumber region, a peak at approximately 100 cm−1, attributable to a mixed mode of methylene lateral motion and amide group stretching, was observed. Additionally, a new band at approximately 60 cm−1 was observed and assigned to molecular chain torsions in the α-form. Both bands indicated that molecular chain rotation occurs prior to the Brill transition at approximately 130 °C. In the high-wavenumber region, bands at approximately 1126 cm−1 and 1060 cm−1 indicated a simultaneous weakening of C–C stretching modes in the trans conformation at the same temperature, consistent with observations in the low-wavenumber region.
期刊介绍:
An international, peer-reviewed journal covering all of the chemical sciences, including multidisciplinary and emerging areas. RSC Advances is a gold open access journal allowing researchers free access to research articles, and offering an affordable open access publishing option for authors around the world.