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Effects of solvents and temperature on spherulites of self-assembled phloroglucinol tristearate

Yawen Yao, Sabine Rosenfeldt, Kai Zhang

《化学科学与工程前沿（英文）》 2020年 第14卷 第3期   页码 389-396 doi: 10.1007/s11705-019-1911-3

摘要： Herein, phloroglucinol tristearate (PhgTS) was used to study the crystallization process due to its unique symmetric structure containing a benzene ring and three aliphatic chains. Spherulites of crystallized PhgTS from four solvents under diverse conditions were analyzed in detail and their formation process was studied. Maltese cross is shown by PhgTS spherulites obtained from aprotic solvents via polarized optical microscopy. In comparison, no Maltese cross can be observed from branch-like crystals formed from protic solvents. Independent on the microscaled morphology, lamellae were found to be the basic blocks constructing both PhgTS spherulites and branch-like crystals, which were formed predominantly by stacked PhgTS molecules. Although differential characters of the solvents did not affect the formation of lamellas, the solvents played a crucial role in the formation of self-assembled microscaled morphologies. In particular, the morphologies of spherulites were strongly affected by the concentration of PhgTS solutions, surrounding temperature and evaporation rate of solvents. Generally, a higher concentration of PhgTS led to more homogeneous spherulites, a lower evaporation rate resulted in more compact spherulites, and a higher surrounding temperature generated preferentially more ring-banded spherulites of PhgTS.

关键词： phloroglucinol     tristearate     aprotic and protic solvent     self-assembly     spherulites    

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Study on the crystal morphology and melting behavior of isothermally crystallized composites of short carbon fiber and poly(trimethylene terephthalate)

Mingtao RUN, Hongzan SONG, Yanping HAO

《化学科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 255-264 doi: 10.1007/s11705-009-0008-9

摘要： The spherulites of the short carbon fiber(SCF)/poly (trimethylene terephthalate) (PTT) composites formed in limited space at designed temperatures, and their melting behaviors were studied by the polarized optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. The results suggest that SCF content, isothermal crystallization temperatures, and the film thicknesses influence the crystal morphology of the composites. The dimension of the spherulites is decreased with increasing SCF content, but whether banded or nonbanded spherulites will form in the composites is not dependent on SCF content. However, the crystal morphology of the composites depends strongly on the temperature. When the isothermal crystallization temperatures increase from 180°C to 230°C, the crystal morphology of SCF/PTT composites continuously changes in the following order: nonbanded → banded → nonbanded spherulites. Discontinuous circle lines form in the film when the film thickness increases from 30 to 60 μm. Basing on the SEM observation, it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the spherulites. These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room temperature at a slow cooling rate; while they will disappear gradually at different temperatures in the heating process. The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated. The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the spherulites.

关键词： poly(trimethylene terephthalate)     short carbon fiber     banded spherulites     crack    

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标题 作者 时间 类型 操作

Effects of solvents and temperature on spherulites of self-assembled phloroglucinol tristearate

Yawen Yao, Sabine Rosenfeldt, Kai Zhang

期刊论文

Study on the crystal morphology and melting behavior of isothermally crystallized composites of short carbon fiber and poly(trimethylene terephthalate)

Mingtao RUN, Hongzan SONG, Yanping HAO

期刊论文