{"title":"可生物降解聚乙二醇中的晶体结构演变和空化:热拉伸过程中的原位 WAXD/SAXS 研究","authors":"","doi":"10.1016/j.polymer.2024.127517","DOIUrl":null,"url":null,"abstract":"<div><p>The structural evolution of high-crystallinity polyglycolide (PGA) during hot-stretching from 50 °C to 150 °C was investigated using synchrotron in-situ WAXD/SAXS techniques. The structural evolution during stretching at different temperatures can be divided into three stages. The stage preceding the yield point, the lamellar crystals undergo extensive slip due to shear forces. The crystallite size decreases by 43.9 % during stretching at 50 °C, while it only decreases by 23.8 % at 150 °C. In this stage, cavities with their long axes vertical to the stretching direction form between the lamellar stacks parallel to the stretching direction. Higher stretching temperatures are less favorable for the formation of these cavities. Stage from yield point to onset of strain hardening, some of the small crystals formed in the previous stage accumulate in the oblique direction. After reaching the critical strain, they reorient towards the stretching direction. This reorientation causes fragmentation and recrystallization, promoting the further development of cavities. Both the cavities and the recrystallized crystals align along the stretching direction. In the strain-hardening stage, new crystal formation occurs under stress, and higher temperatures favor the formation of highly oriented crystals. As a result, the crystallinity and crystal orientation of PGA at the end of stretching are positively correlated with the stretching temperature.</p></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":null,"pages":null},"PeriodicalIF":4.1000,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Crystal structural evolution and cavitation in biodegradable polyglycolide: An in-situ WAXD/SAXS study during hot-stretching\",\"authors\":\"\",\"doi\":\"10.1016/j.polymer.2024.127517\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The structural evolution of high-crystallinity polyglycolide (PGA) during hot-stretching from 50 °C to 150 °C was investigated using synchrotron in-situ WAXD/SAXS techniques. The structural evolution during stretching at different temperatures can be divided into three stages. The stage preceding the yield point, the lamellar crystals undergo extensive slip due to shear forces. The crystallite size decreases by 43.9 % during stretching at 50 °C, while it only decreases by 23.8 % at 150 °C. In this stage, cavities with their long axes vertical to the stretching direction form between the lamellar stacks parallel to the stretching direction. Higher stretching temperatures are less favorable for the formation of these cavities. Stage from yield point to onset of strain hardening, some of the small crystals formed in the previous stage accumulate in the oblique direction. After reaching the critical strain, they reorient towards the stretching direction. This reorientation causes fragmentation and recrystallization, promoting the further development of cavities. Both the cavities and the recrystallized crystals align along the stretching direction. In the strain-hardening stage, new crystal formation occurs under stress, and higher temperatures favor the formation of highly oriented crystals. As a result, the crystallinity and crystal orientation of PGA at the end of stretching are positively correlated with the stretching temperature.</p></div>\",\"PeriodicalId\":405,\"journal\":{\"name\":\"Polymer\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":4.1000,\"publicationDate\":\"2024-08-19\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Polymer\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S003238612400853X\",\"RegionNum\":2,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"POLYMER SCIENCE\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Polymer","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S003238612400853X","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"POLYMER SCIENCE","Score":null,"Total":0}
引用次数: 0
摘要
利用同步辐射原位 WAXD/SAXS 技术研究了高结晶度聚乙二醇(PGA)在 50 °C 至 150 °C 热拉伸过程中的结构演变。不同温度拉伸过程中的结构演变可分为三个阶段。在屈服点之前的阶段,片状晶体在剪切力的作用下发生大面积滑移。在 50 °C 的拉伸过程中,晶体尺寸减少了 43.9%,而在 150 °C 的拉伸过程中,晶体尺寸只减少了 23.8%。在这一阶段,平行于拉伸方向的薄片堆之间形成了长轴垂直于拉伸方向的空穴。拉伸温度越高,越不利于这些空腔的形成。从屈服点到应变硬化开始的阶段,前一阶段形成的一些小晶体在斜方向上堆积。达到临界应变后,它们会向拉伸方向重新定向。这种重新定向会导致碎裂和再结晶,促进空洞的进一步发展。空穴和再结晶晶体都沿拉伸方向排列。在应变硬化阶段,新晶体在应力作用下形成,较高的温度有利于高取向晶体的形成。因此,拉伸结束时 PGA 的结晶度和晶体取向与拉伸温度呈正相关。
Crystal structural evolution and cavitation in biodegradable polyglycolide: An in-situ WAXD/SAXS study during hot-stretching
The structural evolution of high-crystallinity polyglycolide (PGA) during hot-stretching from 50 °C to 150 °C was investigated using synchrotron in-situ WAXD/SAXS techniques. The structural evolution during stretching at different temperatures can be divided into three stages. The stage preceding the yield point, the lamellar crystals undergo extensive slip due to shear forces. The crystallite size decreases by 43.9 % during stretching at 50 °C, while it only decreases by 23.8 % at 150 °C. In this stage, cavities with their long axes vertical to the stretching direction form between the lamellar stacks parallel to the stretching direction. Higher stretching temperatures are less favorable for the formation of these cavities. Stage from yield point to onset of strain hardening, some of the small crystals formed in the previous stage accumulate in the oblique direction. After reaching the critical strain, they reorient towards the stretching direction. This reorientation causes fragmentation and recrystallization, promoting the further development of cavities. Both the cavities and the recrystallized crystals align along the stretching direction. In the strain-hardening stage, new crystal formation occurs under stress, and higher temperatures favor the formation of highly oriented crystals. As a result, the crystallinity and crystal orientation of PGA at the end of stretching are positively correlated with the stretching temperature.
期刊介绍:
Polymer is an interdisciplinary journal dedicated to publishing innovative and significant advances in Polymer Physics, Chemistry and Technology. We welcome submissions on polymer hybrids, nanocomposites, characterisation and self-assembly. Polymer also publishes work on the technological application of polymers in energy and optoelectronics.
The main scope is covered but not limited to the following core areas:
Polymer Materials
Nanocomposites and hybrid nanomaterials
Polymer blends, films, fibres, networks and porous materials
Physical Characterization
Characterisation, modelling and simulation* of molecular and materials properties in bulk, solution, and thin films
Polymer Engineering
Advanced multiscale processing methods
Polymer Synthesis, Modification and Self-assembly
Including designer polymer architectures, mechanisms and kinetics, and supramolecular polymerization
Technological Applications
Polymers for energy generation and storage
Polymer membranes for separation technology
Polymers for opto- and microelectronics.