POLYMER DEGRADATION AND STABILITY
·
2020
·
IF 4.032
Zhang Xuzhen,Wen Xin,Zhou Chenmeng,Huang Wenjian,Li Yong
Polylactide (PLA) is a representative material in biodegradable polymers, but its application is limited due to the brittleness and poor toughness. In order to investigate the basic brittleness mechanism of PLA, the morphology and formation of spherulite defects in PLA, including ring line cracks with width around 0.3 nm and micropores with diameters of 0.8–1.2 μm, were studied by polarizing microscope and atomic force microscope. The effects of cooling rate, sample thickness, PLA molecular weight, isothermal crystallization temperature and spherulite growth maturity on PLA spherulite defects were discussed. Both ring line cracks and micropores are caused by internal stress caused during PLA melt cooling process, and their morphology would be changed by internal stress distribution with various factors mentioned above. The inhibition of crystal defects will potentially improve the mechanical properties of PLA, thus these results will provide useful references for the toughening modification of PLA.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2021
·
IF 7.514
Yuying Hu,David Julian McClements,Lufeng Wang,Chunmei Li
Potato starch spherulites (PSS) with different molecular weights were obtained by controlled enzymatic hydrolysis of potato amylose starch, followed by super-heated quenching treatment. The impact of enzymatic hydrolysis on mean particle diameter and molecular weight was observed, ranging from 355 to 57 nm. Structural and physicochemical characteristics of produced spherulites were determined using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and rheological measurements. Rheological analysis indicated that PSS sample was viscoelastic with shear-thinning behavior. PSS was found to exhibit weak B-type crystallinity, similarly to that in native starch. PSS 25% had a higher thermal stability with 128.5 °C melting temperature. Microstructure confirmed there were small spherulites (1–3 μm) formed with hydrolyzed amylose starch, and starch with 15% enzymatic-hydrolysis degree was more beneficial to develop spherulite. These results may be useful in development of starch-based functional ingredients applied in plant-based foods as fat replacers, structure formers, or delivery systems.
研究领域:
食品科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Dongbo Wang,Xuan Zhou,Yanbo Liu,Mingyang Chen,Dandan Han,Junbo Gong
With the rise of research on functional sugar, we found that preparing crystalline powders into spherical crystals will significantly improve quality, stability, appearance, and texture. In this work, d-ribose (D-RIB) spherical crystal aggregates were prepared for the first time. And D-RIB spherical crystal aggregates with superior filterability, flowability, and tap density can be prepared in ethanol, 1-propanol, and isopropanol. Specifically, we used ethanol as an example to reveal the formation mechanism of D-RIB spherical crystal aggregates: solvent-induced crystal defects, which in turn trigger noncrystallographic branching and further spherulite growth. Finally, a comparison of the properties of the D-RIB spherical crystal aggregates with those of commercially available products is given, demonstrating the fabrication of D-RIB spherulites with better tap density and flowability by solvent-induced noncrystallographic branching. This will provide a new insight into the preparation of high-quality D-RIB crystals.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2024
·
IF 4.1
Tiantian Song,Weichao Shi
Solvent evaporation is a dynamic process associated with mass transfer, heat exchange and complex internal flow . Their complicated effects on crystallization remain unclear in evaporating sessile droplets. Here, we study crystallization in evaporating poly(ethylene oxide) (PEO) sessile droplets and obtain three kinds of spherulites with monochromatic, anisotropic or negative birefringence . Monochromatic spherulites are generated at very slow solvent evaporation and low molecular weight , while high anisotropic spherulites are created under flow field at rapid solvent evaporation and large molecular weight . Ordinary negative spherulites appear at intermediate conditions. The temperature variation is verified during solvent evaporation, but plays an insignificant thermodynamic effect on crystallization. The experimental findings are further validated in different solvents and polymer systems . This work establishes the relationship between solvent evaporation and polymer crystallization in sessile droplets and also provides a guideline for modulating optical properties of deposited films using droplet processing techniques.
研究领域:
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2015
·
IF 4.891
Jingxiang Yang,Yongli Wang,Hongxun Hao,Chuang Xie,Ying Bao,Qiuxiang Yin,Junbo Gong,Chen Jiang,Baohong Hou,Zhao Wang
L-Tryptophan was successfully crystallized in the form of spherulites by introducing trace amounts of gelatin into the crystallization solution. The physicochemical properties of L-tryptophan products were significantly improved by using this polymer-induced spherulitic growth strategy. This newly developed polymer-induced spherulitic growth strategy provides another choice for controlling the size distribution of particles. Furthermore, the formation and growth of these spherulites under different conditions was monitored in situ by using particle vision measurement and microscopy. It was found that the morphologies of spherulites could be influenced by the additives, the crystallization temperature, and the initial concentration of L-tryptophan. The influence of temperature on the growth rate of spherulites was investigated. It was found that the growth rate is constant at given temperatures. A population-based empirical model was developed and used to explain the spherulitic growth of L-tryptophan spherulites. It was verified that the growth of L-tryptophan spherulites is interface kinetics controlled.
研究领域:
化学工程
·
材料科学
·
药物结晶
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2020
·Vol. 39
·期 4
·493-500
·
IF 3.154
Meng Xiao-Yu,Li Yi,Yao Shu-Fang,Wei Xue-Wei,Ye Hai-Mu
Spherulites are the most common crystalline morphology and thus the visual expression of crystal structures for polymers. The diversified patterns have provided intuitive morphology probes for various crystallization behaviors, while the correlations between them are still needed to be enriched. In this work, the complicated spherulitic morphology of poly(propylene fumarate) (PPF), which is sensitive to crystallization temperature, is investigated. PPF melt, respectively, crystallizes into rough spherulites, regularly banded spherulites, and spherulites containing both two kinds of morphology at low, high, and mediate temperatures. By systematically assaying, it is clear that the growth axis along the radial direction changes from a -axis to b -axis as the crystallization temperature increases, which leads to the formation of unique crystallization-temperature-dependent spherulites. Based on detailed characterization of Fourier transform infrared spectroscopy, the packing state of the specific hydrogen bonds of “C=C-H⋯O=C-C=C” in PPF crystal lattices is determined, and furthermore, the mechanism for temperature-dependent selection of growth axes for PPF spherulites in melt is reasonably speculated.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
POLYMER
·
2019
·
IF 3.771
Ming Zhang,Mingqing Chen,Zhongbin Ni
Currently, it remains a challenge to effectively improve the toughness of epoxy polymer without impairing the processability and other properties. Herein, a novel strategy was proposed for toughening epoxy polymer using the ordered microstructure formed by the self-assembly of C 8 H 17 -alkyl branched tri-carbamates with a spacer of isocyanurate ring at relatively low concentrations in the epoxy/amine system. The employed tri-carbamates slightly affects the viscosity of the modified epoxy due to its low molecular weight and melting behavior. The dendritic spherulites microstructures self-assembled in epoxy matrix through the desired molecular interactions between branched alkyl chains, –NHCOO– and C O act as the toughening materials that absorb fracture energy and subsequently improve the impact resistance of cured epoxy without significantly sacrificing Tg and mechanic strength . Moreover, due to the good plasticization of branched C 8 H 17 - chains and excellent mechanic strength of isocyanurate ring, in-situ dispersing tri-carbamates endows the modified epoxy the balanced cured properties.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Advanced Optical Materials
·
2025
·
IF 7.2
Yuanfeng Liu,Le Zhou,Kristiaan Neyts,Jingbo Sun,Ji Zhou
So far, second harmonic generation (SHG) is usually obtained through ferroelectric materials with spontaneous polarization because of the broken spatial inversion symmetry. In recent years, ferroelectric systems with topological defects such as vortex domains have aroused great research interest. The SHG response from such ferroelectric topological structures is intriguing toward SHG applications and topological characterizations. In this work, a spherulite material with a single ferroelectric vortex domain is synthesized and studied on its ferroelectric properties and optical nonlinearity. The spherulite material is in a sphere-cap shape, composed of polar molecules RM734, with both the average molecular orientation and the polarity arranged azimuthally, forming a single vortex domain, which is demonstrated by the ferroelectric hysteresis loop and piezoelectric force microscopy. Such a large single vortex domain can produce second-order nonlinearity with local polarity features, which are, in turn, used to characterize the topological structure of the ferroelectric vortex domain. The topological similarity between such a single vortex domain material and the optical vortex beam may shed light on promising ways of optical vortex generation.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTENGCOMM
·
2015
·Vol. 18
·期 2
·274-282
·
IF 4.034
Jun Shao,Yanmei Guo,Sheng Xiang,Dongdong Zhou,Xinchao Bian,Jingru Sun,Gao Li,Haoqing Hou
Linear and three-armed poly(L-lactide)/poly(D-lactide) (PLLA/PDLA, 3PLLA/3PDLA and 3PLLA/PDLA) specimens were prepared through a solution mixing method, and the morphology and the spherulite growth of poly(lactide) stereocomplex crystallites (PLA sc) from the melt with various structures and molecular weights were investigated. Polarized optical microscopy images revealed that regular spherulites and a visible boundary developed in all of the PLLA/PDLA blends with relatively lower molecular weights (Mn < 20 kg mol−1 for each branch), and irregular spherulites formed when the molecular weights of PLA polymers were higher than 60 kg mol−1. The growth rate of the spherulites (G) increased at first, and then decreased as the molecular weight increased in all of the PLLA/PDLA, 3PLLA/3PDLA and 3PLLA/PDLA specimens. The highest G value in all of the specimens was achieved when the average molecular weights of each branch were ∼10 kg mol−1. With similar molecular weights for each of the branches, the G reduced gradually as the three-armed PLA was added to the blend (i.e., PLLA/PDLA > 3PLLA/PDLA > 3PLLA/3PDLA).
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Pingping Cui,Wenchao Yang,Lihong Jia,Ling Zhou,Meijing Zhang,Ying Bao,Chuang Xie,Baohong Hou,Qiuxiang Yin
In industrial crystallization, spherical crystals have gained increasing interest due to their excellent physicochemical properties, such as high bulk density, flowability, stability, etc. However, their formation mechanism is still not well understood and is often oversimplified. In this work, spherical amoxicillin sodium crystals were obtained via a spherulitic growth strategy. It was found that agitation immediately after the addition of crystal seeds was critical for inducing radial noncrystallographic branching and spherulite formation of amoxicillin sodium. Without agitation during the aging period after seed addition, only discrete rod-shaped crystals were obtained. The formation mechanism of amoxicillin sodium spherulites was studied using process analytical technology (PAT) tools, including focused beam reflectance measurement (FBRM) and particle video microscope (PVM). The result was indicative of a three-step morphological evolution process: formation of polycrystalline agglomerates, noncrystallographic branching, and spherulite growth. During this process, agitation immediately after seed addition could help to solute diffusion and induce the agglomeration of small crystals that result from secondary nucleation. The polycrystalline agglomerates serve as the cores for further noncrystallographic branching and growth. On this basis, a new spherulitic growth strategy was proposed by the large addition of crystal seeds as the growth substrates of new branching and spherulite growth. High agitation rates during the aging period can increase the mass ratio of spherulites, and high initial supersaturation can promote branching. Compared with the discrete rod-shaped crystals, spherulites self-regulate the final size greatly up to three times and have a higher bulk density as well as much lower hygroscopicity.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2021
·
IF 3.764
Wei Li,Jing Yang,Shichao Du,Estevao Macaringue,Yan Wang,Songgu Wu,Junbo Gong
l-Valine crystallizes in a flake-like shape generally; however, compared with the flake-like products, spherulitic l-valine has better filterability, flowability, and bulk density and has potential for wider industrial applications in the future. In this study, l-valine spherulites have been successfully prepared by an evaporative crystallization method in the presence of no more than 0.5% hydroxypropyl methyl cellulose (HPMC). The spheroidization of l-valine proceeds via a layer-by-layer transformation from an initial flake-like shape to a petal-like form, and then it continues to grow into the final sphere-like shape. Molecular dynamics simulations show that HPMC interacts with hydrophilic (001) faces preferentially and promotes the continuous layer growth process. Only the substituent groups of hydroxypropyl and methyl exist simultaneously within a certain spatial distance and, in a viscosity of 40–50 mPa·s, can promote the formation of l-valine spherulites. The particle size increased with the increase in the HPMC dosage and decrease of temperature or evaporation rate. This effect of HPMC promoting the spherical formation provides a method to enrich the design of spherulites and new insights into the fabrication mechanism of spherulitic growth.
研究领域:
化学
·
材料科学
·
晶体学
✓ 已验证
DOI
高影响因子
POLYMER
·
2024
·
IF 4.1
Guangxu Ju,Jinzhu Tang,Qunfeng Cheng,Chunming Wang,Rui Liang,Guoxing Sun
Thermosensitive hydrogels have gained increasing attention due to their diverse applications in drug delivery and as wearable sensors. However, their practical utility is hampered by their inherent weak mechanical properties. To overcome this limitation, a tough thermosensitive hydrogel was developed by incorporating non-aggregated spherulite nanoparticles into the system. The hydrogel of poly (N-isopropylacrylamide) (PNIPAM) and calcium hydroxide nano-spherulites (CNS) exhibits a broad temperature response from 0 to 100 °C and good thermosensitivity after ten cycles in swelling experiments. The exceptional mechanical properties with a maximum tensile strength of 82.05 kPa, an elongation at break of about 3200 %, which returns to 88 % of its original size after a compressive load of 16.17 MPa, and an adhesion strength to latex of 32.45 kPa. In addition, each gram of PNIPAM/CNS hydrogel can hold 18.488 mg of AMX , which shows its potential application in many fields such as drug delivery, skin healing, bionics , etc.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）