{"title":"Degradation phenomenon of compostable poly(lactic acid) films induced by pure halogenated liquid chemicals and mixtures with water","authors":"Mingyin Hsiao, Kazukiyo Nagai","doi":"10.1016/j.polymdegradstab.2024.110997","DOIUrl":null,"url":null,"abstract":"<div><p>A circular economy requires that plastic packaging should be recyclable or compostable as well as reusable. Compostable/biodegradable poly(lactic acid) (PLA) is an alternative to conventional packaging materials for films, bags, and containers. Packaging is not only for food and beverages but also for medicine, agricultural chemicals, industrial chemicals, and waste solvents such as chlorinated solvents, which sometimes contain water. This study determined that PLA films were completely soluble in dichloromethane and chloroform, insoluble but strongly swollen in trans-1,2-dichlorocycrohexane, o-dichlorobenzene, and carbon tetrachloride, and insoluble with retained film shape in tetrachloroethylene (TCE), 1,2,4-trichlorobenzene (1,2,4-TCB), and 1-bromonaphthalene (1-BN). The equilibrium mass uptake values of pure insoluble solvents in PLA films were 0.977 ± 0.219 wt% for TCE, 1.716 ± 0.631 wt% for 1,2,4-TCB, and 3.351 ± 1.936 wt% for 1-BN. After sorption of the three insoluble pure solvents, the α’-type crystals of PLA films changed to α-type crystals. This phenomenon was based on the molecular size and electrostatic potential value of the solvents. When insoluble solvents were mixed with water, the water-in-oil mixture enhanced the mass uptake for TCE and 1,2,4-TCB but reduced it for 1-BN. The oil-in-water mixture distinctly reduced the solubility for all solvents. The α-type crystal structure was stable in TCE and 1-BN. If an industrially appropriate method of α-type crystal structure formation could be realized selectively, then PLA could be used as packaging materials for films, bags, and containers for these solvents without any further modification.</p></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"229 ","pages":"Article 110997"},"PeriodicalIF":6.3000,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0141391024003410/pdfft?md5=34293896cd0fbc56ffbd24f32cc21946&pid=1-s2.0-S0141391024003410-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Polymer Degradation and Stability","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0141391024003410","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"POLYMER SCIENCE","Score":null,"Total":0}
引用次数: 0
Abstract
A circular economy requires that plastic packaging should be recyclable or compostable as well as reusable. Compostable/biodegradable poly(lactic acid) (PLA) is an alternative to conventional packaging materials for films, bags, and containers. Packaging is not only for food and beverages but also for medicine, agricultural chemicals, industrial chemicals, and waste solvents such as chlorinated solvents, which sometimes contain water. This study determined that PLA films were completely soluble in dichloromethane and chloroform, insoluble but strongly swollen in trans-1,2-dichlorocycrohexane, o-dichlorobenzene, and carbon tetrachloride, and insoluble with retained film shape in tetrachloroethylene (TCE), 1,2,4-trichlorobenzene (1,2,4-TCB), and 1-bromonaphthalene (1-BN). The equilibrium mass uptake values of pure insoluble solvents in PLA films were 0.977 ± 0.219 wt% for TCE, 1.716 ± 0.631 wt% for 1,2,4-TCB, and 3.351 ± 1.936 wt% for 1-BN. After sorption of the three insoluble pure solvents, the α’-type crystals of PLA films changed to α-type crystals. This phenomenon was based on the molecular size and electrostatic potential value of the solvents. When insoluble solvents were mixed with water, the water-in-oil mixture enhanced the mass uptake for TCE and 1,2,4-TCB but reduced it for 1-BN. The oil-in-water mixture distinctly reduced the solubility for all solvents. The α-type crystal structure was stable in TCE and 1-BN. If an industrially appropriate method of α-type crystal structure formation could be realized selectively, then PLA could be used as packaging materials for films, bags, and containers for these solvents without any further modification.
期刊介绍：
Polymer Degradation and Stability deals with the degradation reactions and their control which are a major preoccupation of practitioners of the many and diverse aspects of modern polymer technology.
Deteriorative reactions occur during processing, when polymers are subjected to heat, oxygen and mechanical stress, and during the useful life of the materials when oxygen and sunlight are the most important degradative agencies. In more specialised applications, degradation may be induced by high energy radiation, ozone, atmospheric pollutants, mechanical stress, biological action, hydrolysis and many other influences. The mechanisms of these reactions and stabilisation processes must be understood if the technology and application of polymers are to continue to advance. The reporting of investigations of this kind is therefore a major function of this journal.
However there are also new developments in polymer technology in which degradation processes find positive applications. For example, photodegradable plastics are now available, the recycling of polymeric products will become increasingly important, degradation and combustion studies are involved in the definition of the fire hazards which are associated with polymeric materials and the microelectronics industry is vitally dependent upon polymer degradation in the manufacture of its circuitry. Polymer properties may also be improved by processes like curing and grafting, the chemistry of which can be closely related to that which causes physical deterioration in other circumstances.
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