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In this research, the formation of ring band spherulite of poly(lactic acid) (PLA) under carbon dioxide (CO2) was in‐situ studied and the internal lamellar arrangement of ring band spherulite formed under CO2 was revealed for the first time. The spherulites by PLA crystallized under air and different CO2 pressures have been studied, and the surface and internal lamellar arrangement of the ring band spherulites have also been analyzed in detail. It was found that PLA would form ring band spherulite under air and 6 MPa CO2, while the internal structures of the two types of ring band spherulites were different. The surface height difference of ring band spherulites formed under air was small, at 278.9 nm, and the twisting angle of the lamellae was also small. However, the difference in the surface height of the ring band spherulite formed under 6 MPa CO2 was big, reaching 778.3 nm. Through analysis on the internal lamellar arrangement of the ring band spherulite, it was found that the valley for the ring band spherulites formed under 6 MPa CO2 was composed of flat‐on lamellae, the ridge was composed of edge‐on lamellae and the sudden twist occurred between the flat‐on lamellae and edge‐on lamellae. [ABSTRACT FROM AUTHOR]

Waxes and monoglycerides (MGs) added in edible oils form oleogels that can be used as an alternative structured fat, providing healthier substitutes to saturated and trans fats in foods. This study aimed to investigate the properties of oleogels formed by the interaction between monoglycerides and different waxes in various edible oils. For this purpose, waxes, namely rice bran (RBW), candelilla (CDW), sunflower (SW), and beeswax (BW), together with MGs in a total concentration level of 15% (w/w) were dissolved in several edible oils (olive, sunflower, sesame, and soybean). The structure and physical properties of oleogels were investigated using texture analysis, polarized light microscopy, melting point measurements, and Fourier-transform infrared spectroscopy (FTIR). The hardest structure was produced by SW/MG (5.18 N), followed by CDW (2.87 N), RBW (2.34 N), BW (2.24 N) and plain MG (1.92 N). Furthermore, RBW and SW led to a higher melting point (69.2 and 67.3 °C) than the plain MG oleogels (64.5 °C). Different crystallization structures, i.e., needle-like crystals and spherulites, were observed depending on the type of wax, its concentration, and the oil used. These results can be used to control the properties of oleogels by adjusting the gelator composition for a variety of potential food applications. [ABSTRACT FROM AUTHOR]

Two-dimensional transition-metal carbides and nitrides (MXenes) are a large family of materials actively studied for various applications, especially in the field of energy storage. MXenes are commonly synthesized by etching the layered ternary compounds, called MAX phases. We demonstrate a direct synthetic route for scalable and atom-economic synthesis of MXenes, including compounds that have not been synthesized from MAX phases, by the reactions of metals and metal halides with graphite, methane, or nitrogen. The direct synthesis enables chemical vapor deposition growth of MXene carpets and complex spherulite-like morphologies that form through buckling and release of MXene carpet to expose fresh surface for further reaction. The directly synthesized MXenes showed excellent energy storage capacity for lithium-ion intercalation. [ABSTRACT FROM AUTHOR]

Three ceramic fibrous materials of the Al2O3-SiO2 system with different densities have been treated using concentrated solar radiation. The experiment was performed using technological capabilities of the Big Solar Furnace in the 2 modes: the first mode includes heating up to 1400–1600 °C, holding for 1.5–2 h; the second mode (the fusion mode) includes heating up to 1750–1900 °C until the sample destruction, which is accompanied by fusion. Upon completion of the experiment, the phase composition, microstructure, and compressive strength of the materials were studied. It was shown that the investigated materials retained their fibrous structure under prolonged treatment in the first mode up to temperatures of 1600 °C. The phase composition of the ceramic materials changes during the experiment, and with a decrease in the density, the modification is more pronounced. Treatment of all three materials under study in the fusion mode resulted in the formation of the eutectic component in the form of spherulites. The compressive strength of the materials was found to be slightly reduced after exposure to concentrated solar radiation. [ABSTRACT FROM AUTHOR]

Rhabdophane (Ce0:34-0:43Nd0:13-0:14Ca0:06-0:29La0:08-0:11Y0:05-0:12Pr0:03-0:05Sm0:02-0:05 Gd0:02-0:05Fe0-0:04Dy0:00-0:01/0:97-1:01((P0:69-0:96S0:04-0:31/1:00O4/qH2O is found in a Fe3C-oxyhydroxide nodule (brown iron ore) collected from the upper part of the oxidation profile of the Babaryk massive sulfide occurrence (South Urals, Russia) at a 1.6m depth. The structural and microtextural features of rhabdophane are revealed by electron backscattered diffraction (EBSD); the chemical composition and distribution of the main components are determined on a scanning electron microscope (SEM) equipped with an energy-dispersive analyzer (EDA); the bulk contents of rare earth elements (REEs) and other elements in rock samples are analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Rhabdophane forms spherulitic aggregates up to 35 µm in size with a fine-grained core and radial radiant rims composed of prismatic crystals. The chaotically oriented aggregates of its particles of various sizes including prismatic crystals and spherulitic intergrowths also fill fractures up to 200 µm long and 20-30 µm thick in goethite. The zonal radial radiant structure of the rhabdophane aggregates and their occurrence in fractures of goethite unambiguously indicate the authigenic origin of rhabdophane. The chemically heterogeneous rhabdophane grains always contain Y, Ca and S and rarely Fe and Sr and are Th- or U-free. Contrasting zonation of Ca, S and Y contents is characteristic of spherulites. The band contrast of the EBSD patterns shows a good crystallinity of prismatic crystals regardless of the chemical composition even for Ca-S-rich zones. On the other hand, the Ca- and S-rich fine-grained centers of the spherulites do not yield any distinguishable diffraction patterns. There is a strong negative correlation in pairs (CaCSr)-P and (REEsCY)-S and a positive correlation in pairs (CaCSr)-S and (REEsCY)-P, which indicates the isomorphism according to the scheme (REEsCY)3C C (PO4/3- $ (CaCSr)2C C (SO4/2-. Thus, the chemical composition of rhabdophane does not completely correspond to the rhabdophane-tristramite/brockite series because of the absence of tetravalent U or Th. In contrast to similar samples from the deeper part of the oxidation zone, the brown iron ore with rhabdophane is enriched in light rare earth elements (LREEs) and P. The REEs were probably sourced from ore-bearing volcanomictic rocks, while P could also have been derived from the soil. The enrichment in REEs and P and the formation of rhabdophane are related to the alternation of dry and wet periods, the P input, and sorption-desorption of REEs from Fe3C oxyhydroxides and/or clay minerals due to pH changes and variable composition of pore water. [ABSTRACT FROM AUTHOR]

Herein, a benchtop technique to create one‐to‐one plastic replicas of nanostructured "masters" of various materials and dimensions via polycarbonate (PC) molding under ambient conditions is described. Instead of conventional thermal molding of PC under high temperature and pressure, it is explored to adapt solvent‐assisted method that has been traditionally unpopular due to the alteration of its morphology induced by swelling and recrystallization. A thorough study of how polymer spherulites (spherical domains of semicrystalline polymer chains) develop and whether their growth can be inhibited by nanocontact molding is conducted; it demonstrated not only how molding drastically limits crystallization but also how the crystallization can be controlled in the process of replicating micro/nanostructures. The efficacy of one‐to‐one replication across length scales from 100 nm to 1 mm over large areas (>5 cm2) has been confirmed with high‐resolution scanning electron microscopy and atomic force microscopy. The durable monolithic PC replicas can be used as templates for casting polydimethylsiloxane (PDMS) devices, allowing expensive lithographically designed masters to be preserved and accelerating production by multiplexing. The simplicity and low cost of this benchtop approach augment the feasibility of nanofabrication in resource‐limited settings with reduced costs and processing time. [ABSTRACT FROM AUTHOR]

The recycling of polymers by manufacturing them into composite materials in processes using natural waste has been of interest due to the appeal to mitigate various environmental problems. Therefore, this study aims to investigate the properties of postconsumer recycled polypropylene (PPrec) composites with 20% (by weight) calcined mollusk shell waste. The calcination was carried out at 500 °C for 12, in order to deagglomerate the particles of the shell calcined (CS). Two more composites were prepared from calcined shell: one CS/CNSL, where CS was treated with the liquid from the cashew nut shell—CNSL (an agricultural by-product) and the other CS/PEG, where CS was treated with polyethylene glycol—PEG (a synthetic product). Based on morphological aspect, PPrec showed nanoparticles of calcium carbonate (CaCO3) well dispersed with size around 290.9 nm. The surface treatment of CS with PEG resulted in composites with voids and agglomerated particles. Some of the CS particles were anchored as well as detached from the matrix. Some clusters involving the CaCO3 nanoparticles and shell microparticles treated with CNSL were observed. The TGA curves revealed an ash content in the range of 9.46% for the recycled Polypropylene, suggesting the presence of CaCO3. The thermal stability of the matrix was improved by adding the calcined shell and also by treating it with CNSL. From the DSC, the degree of crystallinity of the CS/CNSL and CS/PEG composites were similar to that of the PPrec. However, an 11.9% reduction in the crystallinity of composite with CS was observed, which exhibited a broader melting peak indicating that smaller polymer spherulites may be present. The investigation of Mechanical properties allowed to verify an increase in both the tensile and flexural modulus of the PPrec/CS, while CS/CNSL composite presents a mild decrease in the both. In addition, CS particles were more effective in improving the toughness of PPrec, increasing its impact strength by 41%. [ABSTRACT FROM AUTHOR]

We present a thermodynamically consistent theory for solvent-vapor induced spherulitic crystallization in binary thin-film blends, including those which consist of polymeric or organic small-molecule semiconductors. Under the proposed theory, spherulitic growth is interface driven, with no diffusion of any species. The thermodynamic driving force at the interface between the spherulite and amorphous phase is identified, and a kinetic relation that delivers a constant growth rate is proposed. [ABSTRACT FROM AUTHOR]

Dendritic spherulites are one type of diversified ways of crystal aggregations into micrometer-size consortia by kinetics-driven assembly from nanometer-size crystal plates (i.e., lamellae or single crystals). Crystallized polymers can exist in states of different degrees of order, which lead to the resulting assembled morphologies are of non-equilibrium supramolecular hierarchical patterns of crystal structures. Diffusion-controlled growth patterns emerge, which change the details of dendritic morphology depending on Tc (degree of super-cooling), polymer-diluent interactions, confinement. Investigation to the diversified patterns of lamellar assembly into polymer dendritic spherulites has come to several key conclusions. This article reviews and summarizes the top-surface-relief morphology and interior dissections of polymer dendritic spherulites, where the dendrites may be composed of ringed stripes or fibrous cilia crystals. The results yield interesting consistency for constructing workable mechanisms to account for each type of morphologies with respect to their molecular weights and crystallization kinetics conditions (i.e., Tc, space confinements, film thickness, blend interaction, as well as blend composition). [ABSTRACT FROM AUTHOR]

Physical and chemical degradative effects of etching agents on polymer spherulites have been explored thoroughly to understand the etching mechanism as well as to perceive the polymer crystal structure and assembly. Interior lamellae of an aromatic polyester, poly(trimethylene terephthalate) (PTT), crystallized into a well-defined periodic-birefringent spherulitic structure, are subjected to sequence-assorted etching agents of basic methylamine (MA) vapor, acidic permanganate (KMnO 4) reagent, inorganic acids mixture (H 2 SO 4 :H 3 PO 4), and organic dichloroacetic acid (DCA). The chemistry involved in reactions between the selected etchants with the polymer spherulites was probed and their synergistic effects on exposing the interior 3D assembly were assessed. The exposed circumferential alignment of rod-like polycrystals interconnected by nanofibrils signifies the hidden interfaces between the lamellae that are assembled in a periodic grating structure to form banded PTT spherulites. The synergy of sequential MA- and KMnO 4 -etchings revealing the nano-assembly of PTT banded spherulites that resembles circumferential shish and kebabs. Image 1 • Combinatory dual-solvent-etching reveals interior lamellae assembly without causing severe distortion. • Pathways and proper sequence of etching agents provide avenue to better expose the interior assembly in banded spherulites. • Periodically assembly originates from tangential nanofibrils interconnected with radial micrometer-size lamellae bundles. • Contrary to classical models, periodic grating structure, with discontinuity in lamellae, accounts for banded spherulites. [ABSTRACT FROM AUTHOR]

The Fe3O4–thymolblue (TB) functionalized or end capped poly(ε-caprolactone) (PCL) was synthesized by ring opening polymerization (ROP) of ε-caprolactone (CL) with Fe3O4–TB nanohybrid as an effective initiator in the presence of stannous octoate (SO) as a catalyst. The main aim of the present work is to analyze the influence of polymer chain end capping agent or functionalization agent on the structure–property relationship particularly, crystallization and thermal degradation behavior of PCL under non-isothermal condition. The structure of the polymer was analyzed using FTIR and NMR spectra. The particle size of the incorporated Fe3O4–TB nanohybrid in PCL matrix was found to be less than 20 nm by TEM. The surface morphology, skewness moment and surface roughness were analysed by AFM. The spherulitic growth of the nucleated polymer crystals was confirmed by POM. The spherulitic growth was further verified with various kinetic models. The melting and crystallization behaviors under non-isothermal condition were assessed by DSC. Various kinetic models were employed to comprehend the degradation behavior of Fe3O4–TB functionalized PCL and its associated kinetic parameters under non-isothermal condition. The energy of activation (Ea) for the crystallization and thermal degradation of PCL were found to be 132 and nearly 140 kJ/mol respectively. [ABSTRACT FROM AUTHOR]

The aim of this article is to investigate the optical properties of a recycled polymer during numerous processes. The effects of different process parameters (number of grinding‐injection cycles, material temperature, mold temperature, and injection rate) on gloss and color properties of a buff‐colored polypropylene containing 2wt%/wt of pigment was considered. The variations of properties are in the same range that is observed by changing processing parameters. It is found that the roughness is not able to explicate the variation of the optical properties for these variations of conditions. In addition, the optical properties of the skin layer of the injected parts are associated with the observed gloss and color variations. Moreover, the change of spherulite dimensions is related with optical changes. POLYM. ENG. SCI., 59:1288–1299 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Abstract Using poly(3-hydroxybutyrate) (PHB) of two molecular weights and various other polymeric or blend systems, this study has shed a critical clue that cracks are inclined to be guided by interior lamellae via interior inter-lamellae discontinuity and interfaces that exist between the successive ring bands or radial/tangential lamellae. Advanced interior dissection analysis on the aggregated spherulites of several polymers further proves that the cracks occur at the interface between the valley and ridge bands of the ringed spherulites, where interfaces with discontinuous lamellae exist with either impingement or intersection. Propagation of the cracks follows the spiral or circular lamellae assembly into similarly spiral or circular concentric patterns, Such updated views via interior lamellae dissection and analysis on PHB's or other polymers' banded spherulites provide avenues for cracks to develop upon cooling contraction. The mechanism of spiral/circular cracks' formation is well proven in this work, which is related to the inner arrangement/assembly of the periodic spiral lamellae into banded types; by contrast, without such lamellae periodicity, cracks tends to be randomly irregular. Graphical abstract The mechanism of spiral/circular cracks' formation can be well proven to be related to the inner arrangement/assembly of the periodic spiral lamellae into banded spherulites. By contrast, without such lamellae periodicity in spherulites, cracks tends to be randomly irregular. Image 1 Highlights • Mechanism of lamellae assembly in polymer banded spherulites is dissected. • Without orderly lamellae periodicity, cracks tend to be randomly irregular. • Critical clue supports that lamellae have discontinuity/interfaces in banded spherulites. • Interior lamellae in banded spherulites self-assemble into patterns with boundaries. • Spherulite cracks resemble materials in nature assembled with unique interior structures. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Crystal morphology of PHBV depends on the composition distribution of copolymers. • Crystal structure was studied using optical microscopy, DSC and X-ray crystallography. • Narrowly distributed copolymers crystallised in regular banded spherulite morphology. • Copolymer blends displayed interpenetrating crystallisation of separate crystal phases. • Optimizing the crystallisation temperature is key to high performing materials. Abstract The crystallisation of a range of as-produced poly(3-hydroxybutyrate- co -3-hydroxyvalerate) copolymer blends from a mixed culture polyhydroxyalkanoate production process, with low (15%), high (82%) and intermediate (62% and 50%) average 3-hydroxyvalerate (3HV) contents, was studied at different temperatures using polarised optical microscopy, differential scanning calorimetry and X-ray crystallography. The low-3HV content material had narrow compositional distribution and crystallised in the typical highly regular banded spherulite morphology, while the other materials displayed varying degrees of interpenetrating crystallisation of separate crystal phases comprising either the 3HV or 3-hydroxybutyrate (3HB) crystal lattice structure. Because of the differing and competing crystallisation kinetics of these phases coupled with diffusion effects, there was a very strong influence of crystallisation temperature on the resulting morphology. Thus manipulation of the final material properties of such copolymeric materials is dependent on understanding these effects and controlling their processing and crystallisation temperatures and conditions. [ABSTRACT FROM AUTHOR]

Abstract This study addresses the influence of as-cast spherulites, which may be present in the glassy matrix of a bulk metallic glass owing to the processing conditions, on its fracture behaviour. The fracture toughness of a Zr 55 Cu 30 Al 10 Ni 5 glass containing a low fraction as-cast spherulites (∼ 1 % volume fraction) is investigated by means of bending tests. The resulting mode-I fracture toughness values, around 72 MPa m , reveal the moderate detrimental effect of the spherulites. This result is compared to previous results for flawless and dendrite-containing glasses of the same composition, as well as with results from literature. The role played by the spherulites in crack propagation, under mode I and II, and fracture is finally addressed by means of fractography observations and finite element computations. [ABSTRACT FROM AUTHOR]

In this study we investigated the crystallisation behaviours of stereocomplex crystals in poly(l‐lactic acid)/poly(d‐lactic acid) (PLLA/PDLA) blends (LD blends) of various weight ratios. The crystallisation and melting behaviours were studied using DSC, and the crystal structure was analysed through wide‐angle X‐ray diffraction. The morphology of homocrystals and stereocomplex crystals in the blends was examined using a hot‐stage polarising microscope and a scanning electron microscope. The DSC results showed that homocrystals and stereocomplex crystals were present in all LD blends except that with 50 wt% PLLA/50 wt% PDLA; in this blend, only stereocomplex crystals were present. The regime II → III transition temperature of stereocomplex crystals in a Lauritzen–Hoffman plot of the LD blends was determined to be 165 °C. A concentric spherulite consisting of stereocomplex crystals and homocrystals formed under two‐step isothermal crystallisation conditions with three growth stages was observed. The confined spherulitic growth rate in the concentric spherulite and the unrestricted spherulitic growth rate in individual spherulites were also analysed. © 2018 Society of Chemical Industry The morphological evolution of concentric spherulites consisting of stereocomplex crystals and homocrystals formed under two‐step isothermal crystallisation conditions with three growth stages is proposed and described. [ABSTRACT FROM AUTHOR]

Graphical abstract The fabricaiton process of lotus leaf-like superhydrophobic coatings was simplified by using micrometer-sized spherulites as building blocks. Highlights • A facile strategy for the fabrication of lotus leaf-like coating was established. • Lotus leaf-like coatings were prepared without the aid of nanomaterials. • Spherulites was first used as building blocks for superhydrophobic coatings. • Superhydrophobic spherulite coatings can be prepared on different materials. Abstract Micropapillae covered by nanometer-sized wax crystals are essential building blocks of lotus leaf surface for repelling water and self-cleaning. It is generally time-consuming and complex to construct similar artificial micropapillae covered by nanometer-sized protuberances in the fabrication of superhydrophobic coatings without the aid of nanomaterials or special materials. We develop a cost-efficient strategy to simplify the fabrication process of lotus leaf-like superhydrophobic coatings by using micrometer-sized spherulites as building blocks. Well-controlled lotus leaf-like superhydrophobic coatings were prepared from hydrogenated castor oil spherulites through a one-step solution-immersion process. The result coatings have water contact angles over 150° and water shedding angles below 10°. It was demonstrated that micrometer-sized spherulites originated from common material could easily form lotus leaf-like superhydrophobic coatings on different materials through simple crystallization process. [ABSTRACT FROM AUTHOR]

The metastable immiscible Cu 80 Fe 20 alloys with different diameters were systematically investigated under conventional solidification. Experimental results indicated that the primary and second liquid-liquid phase separation simultaneously occur during solidification. The average size of primary phase-separated Fe-rich spherulites and the interior morphological pattern of minority Cu-rich phase can be greatly influenced by cooling rate due to the dynamic coupling between thermodynamic and kinetic effects. Moreover, various morphological patterns of minority Cu-rich phase in Fe-rich spherulites were observed, which discloses the dynamic evolution process during self-driven second liquid-liquid phase separation. The Marangoni migration, coalescence and coagulation, and Ostwald ripening are the dynamic mechanisms mainly responsible for various morphological patterns of minority Cu-rich phase after phase separation. Such a clear experimental observation of dynamic microstructure evolution for minority Cu-rich phase provides a strong and visualized evidence for the asynchronous crystallization behavior of primary phase-separated Fe-rich spherulites. Phase field simulation was also performed to reveal the dynamic evolution of minority Cu-rich phase during liquid-liquid phase separation. Besides, the experimental Cu 80 Fe 20 alloys exhibit soft ferromagnetic characteristics possessing relatively low coercivity and high saturated magnetization. This present study provides a new strategy to design immiscible alloy with anticipated microstructure possessing tailored properties and desired functionalities. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The degree of crystallinity in polymer materials was studied by Raman spectrum. • The degree of crystallinity shows a spatial distribution in the radial direction of spherulite. • The texture originated from crystallinity leads to a spatial distribution of the melting range. Abstract The degree of crystallinity in polymer materials significantly affects their physical properties. However, the distribution of the degree of crystallinity within polymer materials has not been considered even though it should, equally importantly, affect the properties. Herein, we investigate how the degree of crystallinity is spatially distributed in poly(ε -caprolactone) (PCL) films utilizing Raman spectrum. The results indicate that the degree of crystallinity is not uniform throughout the films but presents a distribution along the radial direction of spherulite, with lower degree of crystallinity in the spherulite center. Consequently, the melting range exhibits a similar spatial distribution, with the spherulite center starts to melt at a lower temperature. This work begins to provide an additional structural feature of crystalline polymers that should greatly affect the polymer properties. [ABSTRACT FROM AUTHOR]

Abstract: The preparation of ring‐banded spherulites in poly(3‐butylthiophene) via controlled solvent evaporation of solution‐cast films is reported. The spherulites display unusual concentric ring‐banded structures under both polarized and unpolarized lights. The size of the ring‐banded spherulites is 300 ± 100 µm in diameter and the periodicity of the bands is 15 ± 2 µm. The periodic bands of the spherulite consist of alternating ridge and valley surface patterns and the crystalline lamellae in the bands are more or less parallel to the radial growth direction of the spherulites. Local lamellar bending and branching are observed analogous to that of classical non‐conjugated polymers. A possible diffusion‐induced rhythmic growth mechanism is proposed to interpret the formation of periodic banding of the spherulite. [ABSTRACT FROM AUTHOR]

Starch nanocrystal (SNC) particles were used as the filler to prepare green composites with biodegradable poly(β-hydroxybutyrate) (PHB). An interesting way to tune the nucleation and banded morphology of composites by the surface acetylation of SNC was proposed. Pristine SNC acts as the nucleating agent, while acetylated SNC as the antinucleation one to PHB. This role switching is due to improved polymer-particle compatibility after surface acetylation of SNC particles. The banded structure of PHB spherulites degrades evidently in the presence of two kinds of SNC particles, showing decreased ring-band space, with deteriorated periodicity and increased flocculation of peak-to-valley height. But the two kinds of composites have different mechanisms on the degradation of their ring-bands because the two kinds of SNC particles, pristine SNC and acetylated one, have different influences on the PHB spherulite growth rates and system undercooling. This work also opens a new window for the applications of SNC particles. [ABSTRACT FROM AUTHOR]

Unsaturated copolyesters poly(butylene succinate-co- cis -butene succinate) (P(BS-co- c BS)) were the first time prepared by polycondensation in combination with stannous octoate as catalyst and 4-methoxyphenol as radical inhibitor, achieving linear random copolyesters with a number-average molecular weight up to 38.2 kg/mol. The cis -2-butene-1, 4-diol used in this work showed a peculiarity of no isomerization or cross-linking side reaction even at high reaction temperatures, due to the high chemical stability of the unconjugated cis- double bond. Isodimorphic behavior between butylene succinate (BS) and cis -butane succinate ( c BS) in P(BS-co- c BS) was evidenced by DSC and WAXD analyses. Then, the competition and miscibility of isodimorphism between BS and c BS units were further investigated by thermodynamic analyses. The significant discrepancy in competition and miscibility between BS and c BS units from conformational geometry demonstrated unique physicochemical properties and structure-properties relationships in such system of unsaturated copolyesters. A great impact of competition and miscibility on band spherulites and mechanical properties of the copolyesters was observed and discussed. In conclusion, our work here not only clarifies the effect of cis -double bond on isodimorphism in the unsaturated copolyesters, but also gives an insight into the mechanism of how the competition and miscibility regulates their physical properties. [ABSTRACT FROM AUTHOR]

ABSTRACT: Various annealing temperatures below, near, or above the melting temperature were used to anneal polypropylene with oriented shish kebab and isolated spherulite structures in this work. The results showed that a high annealing temperature decreases the time needed to achieve the ideal material property. When the annealing temperature is near or above the melting temperature, the impact strength would be 1.6 times improved by partial melting and recrystallization. The crystal structure of the oriented shish kebab or isolated spherulite structures was improved when annealed at 150 °C, whereas annealing at 165 or 170 °C recombined the crystal lamellae of the structure. Moreover, the high crystallinity and thick lamellae improved the impact and yield strength values of the spherulite structure. However, excessively high crystallinity and thick lamellae in the oriented shish kebab structure did not result in good mechanical performance. Therefore, the prediction of mechanical properties for the shish kebab structure based on crystallinity and lamellar thickness is not feasible. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46465. [ABSTRACT FROM AUTHOR]

Three star-shaped poly(ʟ-lactide)s (PLLAs) were synthesized, two 6-arm with M w of 120 and 245 kg/mol and one 4-arm with M w of 123 kg/mol. Linear PLLAs with M w of 121 and 339 kg/mol were also prepared. Crystallization, both isothermal and nonisothermal, of all PLLAs was studied by means of DSC. The growth rate of spherulites was measured in a broad range of crystallization temperature using PLM. At M w close to 120 kg/mol the star architecture slowed down the spherulite growth above 120 °C, up to 145 °C. The spherulite growth in PLLAs with M w  > 200 kg/mol was slower than that in the other polymers and unaffected by the macromolecule architecture. The differences in the spherulite growth rate were reflected in overall crystallization kinetics in isothermal conditions and also in crystallization peak temperature and crystallinity developed during cooling. The highest crystallinity developed during isothermal crystallization in linear and 6-arm PLLAs with M w close to 120 kg/mol, whereas the lowest in PLLAs with M w  > 200 kg/mol. For M w  > 200 kg/mol the star architecture decreased the melting temperature. The glass transition temperature of all PLLAs was the same, at 61–62 °C, regardless of M w and macromolecule architecture. [ABSTRACT FROM AUTHOR]

The monomer casting polyamide‐polyether amine (MCPA‐PEA) materials initiated by TDI‐PEA macroinitiator presented an obvious toughness characteristic which was contributed by the combination effect of PEA‐TDI macroinitiator and soft PEA component itself. The MCPA‐PEA materials with different content of PEA‐TDI macroinitiator or PEA component were prepared and then the respective contribution of PEA‐TDI macroinitiator and soft PEA component on the synthesis and performance were researched. It was found that the PEA‐TDI macroinitiator presented the dominant contribution and main influence on the polymerization process with higher activation energy and reaction order than PEA component. The PEA molecular chains did not participated in the crystallization process and made no influence on crystal structure of MCPA material whatever the way of copolymerization or blending. The PEA‐TDI macroinitiator also showed the dominant contribution on the decreasing effect of crystallization properties than PEA component with lower crystallinity and smaller spherulites size. The fibrous‐structure for MCPA‐0.3%PEA matrix was more obvious with notable deformation and high impact strength which further indicated the dominant contribution of PEA‐TDI macroinitiator on toughness. The toughening mechanism was deduced as the vast energy consumption by intense extension of fibrous‐structure and the highly orientation of molecular chains. POLYM. ENG. SCI., 58:1353–1361, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The evaluation method for a biaxially oriented film was developed using in-situ measurement during the stretching process. It can obtain basic data such as stress-strain curves, birefringence, light scattering, three dimensional refractive indexes and birefringence distribution. Stress and strain as functions of stretching speed and stretching temperature, as well as the deformation of spherulite of semi-crystalline polymer can be obtained by measuring the birefringence and light scattering during the biaxial stretching process with a small piece of polymer sample. The experimental results show the stress, retardation and three dimensional molecular orientations behavior during the simultaneous biaxial stretching and the sequential biaxial stretching process. Stretchability, thickness uniformity and spherulite size can be obtained simultaneously. In this paper, advantages and details of the newly developed system will be discussed with some experimental data. [ABSTRACT FROM AUTHOR]

Hierarchical vaterite spherulites, synthesized by a simple injection-precipitation method at room temperature, were applied for the simultaneous removal of heavy metal Cd(II) and dye Congo red (CR) from aqueous solution. Batch experiments reveal that the maximum removal capacities of as-prepared vaterite spherulites to Cd(II) and CR are 984.5 and 89.0 mg/g, respectively, showing excellent removal performance for Cd(II) and CR. Furthermore, in the binary Cd(II)-CR system, the removal capacity of vaterite to Cd(II) is significantly enhanced at lower CR concentration (<100 mg/L), but inhibited at higher CR concentration (>100 mg/L). In contrast, the concurrent Cd(II) shows negligible effect on the CR removal. The simultaneous removal mechanism was investigated by FESEM, EDX, XRD, FT-IR and XPS techniques. The simultaneous removal of Cd(II) and CR in the binary system is shown to be a multistep process, involving the preferential adsorption of dye CR, stabilization of CR to vaterite, coordination of the adsorbed CR molecules with Cd(II), and transformation of vaterite into otavite. Given the facile and green synthesis procedure, and effective removal of Cd(II) and CR in the binary system, the obtained vaterite spherulites have considerable practical interest in integrative treatment of wastewater contaminated by heavy metals and dyes. [ABSTRACT FROM AUTHOR]

Abstract: The study of crystallization behavior and crystalline morphology of polymer melt under shear flow is of great interest due to the strong effect of flow field on the final properties of polymer products in the practical processing. In this respect, the shearing hot stage provides a unique tool which monitors sensitively the changes in crystalline structure induced by precise experimental conditions. Herein, the impacts of both melting temperature and shear rate on the crystallization behavior of isotactic polypropylene (iPP) melt are investigated. Under static conditions, there are only random spherulite structures. Once shear is involved, the cylindrite‐layers appear near both surfaces of the sample, which is consistent with the skin‐core structure in the injection molded parts. Meanwhile, the β‐crystals can be developed and are related to the molecular orientation, depending on the applied melting temperatures and shear rates. More interestingly, the crystallinity of β‐crystal in the pure iPP can reach 15%. The above results indicate that the melting temperature and shear rate are important factors in determining the β‐form crystal development of iPP matrix. [ABSTRACT FROM AUTHOR]

The effects of two metallocene ethylene-propylene-based elastomers (m-EPR1 and m-EPR2) differing in molecular mass and viscosity on mechanical, rheological and interfacial properties were compared. The m-EPR elastomers were added to iPP in 2.5, 5, 10, 15, and 20 vol.%. Torque values, elongation at break and impact strength measured of the iPP/m-EPR1 blends were higher than the iPP/m-EPR2 blends due to higher molten viscosity of m-EPR1 than m-EPR2 copolymer. Slight differences in Young moduli as well as in tensile strength at yield and at break might indicate that tensile properties of iPP/m-EPR blends were not significantly affected by difference in viscosity or molecular mass, miscibility and spherulite size. Optimization diagrams indicated the metallocene m-EPR copolymers are efficient impact modifiers for polypropylene and showed good balancing of mechanical properties in iPP/m-EPR blends. [ABSTRACT FROM AUTHOR]

In the current work, a custom-made vibration injection molding device that can provide oscillatory pressure was utilized to create an injection-molded hierarchical structure. Growth competition among α, β, and γphases in the injection-molded structure can be studied because of the presence of this hierarchical structure, wherein shish-kebab and spherulite layers were arranged alternately along the thickness direction. The γcrystals only existed in layers subjected to high pressure and shear stress, whereas β crystals formed between the shear layers. The change in trend of the γfraction was similar to that of parent-to-daughter ratio. In addition, this hierarchical and alternating crystal structure can sharply increase the mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, the isothermal crystallization kinetics and crystalline morphology of poly(butylene adipate-co-butylene 1,4-cyclohexanedicarboxylate) (PBAC), which refers to a copolyester containing a non-planar ring structure, were investigated by differential scanning calorimetry and polarized optical microscopy, and compared with those of neat poly(butylene 1,4-cyclohexanedicarboxylate) (PBC). The results indicate that the introduction of butylene adipate (BA) unit into PBAC did not change the intrinsical crystallization mechanism. But, the crystallization rate and ability, and equilibrium melting temperature of PBAC copolymers were reduced. All PBC and PBAC copolymers could only form high density of nucleation from melt at given supercooling, while no Maltese cross or ring-banded spherulites could be observed. PBAC copolymers with a high amount of BA unit became amorphous after quenching with liquid nitrogen from melt, while PBC and PBAC copolymers with a low amount of BA unit could still form a large amount of nuclei under the same treatment. [ABSTRACT FROM AUTHOR]

Nature tends to assemble hierarchical structures in similar ways to achieve compactness and functions. This work probes the interior lamellae assembly of crystalline spherulites of poly(ethylene adipate) (PEA) with striking birefringence patterns versus some known biological structures for optical color diffraction. Three-dimensional dissecting onto interior lamellar structures of spherulites in poly(ethylene adipate) (PEA) in bulk forms crystallized at 28 ± 3 °C were studied in correlation with thin-film forms. Interior morphology in bulk PEA samples revealed periodic hemisphere or arc-shaped layers resembling corrugate boards with liner-flute medium alteration. Interior spherulites clearly expose that the lamellae within the intralayer are kebabs (plates) in the radial direction while the interlayer region are thin sheaths (fibrils) composed of cilia-like lamellae in the tangential direction. The interior repetitive lamellar assembly of PEA banded spherulites in displaying periodic optical birefringence patterns is proven to highly resemble those in many biological structures for iridescence light interference. [ABSTRACT FROM AUTHOR]

Bisphenol A polycarbonate (PC) is difficult to crystallize. In this study, it was found that PC could rapidly accomplish melt crystallization only within 8 min by laying poly(ethylene glycol) (PEG) film on it. Polarized optical microscope (POM) was applied to trace the growth of spherulites of PC in PEG/PC double-layer films during isothermal crystallization in a wide range of temperatures, which were above the melting temperature for PEG. The dependence of spherulitic growth rate (G) on isothermal crystallization temperature (Tc) followed a "bell-shape" curve, just like some other semicrystalline polymers did. A PEG film was laid on a PC film at 250 °C for 5 min to obtain a PEG/PC double-layer film, which was subsequently quenched to different Tc's for observation on its crystallization process by using POM. It was surprising to observe that the spherulitic growth rate of PC was significantly improved and the crystallization time was obviously shortened. The miscibility for PEG/PC blends was evaluated by applying differential scanning calorimetry (DSC), which played a crucial role in the crystallization accelerating effect. This method provides an operative way to surmount the particular disadvantages of PC, such as very slow crystallization rate and harsh conditions that PC needs to crystallize in the film processing. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the effect of poly( l‐lactide) (PLLA) components on the crystallization behavior and morphology of poly(ϵ‐caprolactone) (PCL) within PCL/PLLA blends was investigated by polarized optical microscopy, DSC, SEM and AFM. Morphological results reveal that PCL forms banded spherulites in PCL/PLLA blends because the interaction between the two polymer components facilitates twisting of the PCL lamellae. Additionally, the average band spacing of PCL spherulites monotonically decreases with increasing PLLA content. With regard to the crystallization behaviors of PCL, the crystallization ability of PCL is depressed with increase of the PLLA content. However, it is interesting to observe that the growth rate of PCL spherulites is almost independent of the PLLA content while the overall isothermal crystallization rate of PCL within PCL/PLLA blends decreases first and then increases at a given crystallization temperature, indicating that the addition of PLLA components shows a weak effect on the growth rate of the PCL but mainly on the generation of nuclei. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Position-resolved microstructure in a single spherulite of iPP is quantitatively studied by synchrotron microfocus wide angle X-ray scattering. The results show that the normal of mother lamellae in a spherulite is aligned mainly perpendicular to the radius, and the subsidiary daughter lamellae are inclined 80.75° with respect to that of the dominant mother lamellae. The crystallinity in the spherulite is in the range of 46%–56%, which is rarely influenced by the crystallization temperature. The ratio between the daughter lamellae and the mother lamellae is 0.18 when iPP crystallizes at 138 °C and it decreases to 0.11 as the crystallization temperature is decreased to 130 °C. The b- axis and c - axis in the mother lamellae tend to orient perpendicular to the radius direction, and the a -axis prefers to align in the radius direction. [ABSTRACT FROM AUTHOR]

Most classical crystallization analyses on top surfaces of thin films could not adequately reveal the inner assembly of banded spherulites. Interior dissections by fracturing across various spherulite planes should be conducted to justify the inner lamellar assembly underneath the periodic bands. In this study, self-assembly of poly(dodecamethylene terephthalate) (P12T) into banded spherulites has been explored using powerful microscopy approaches. Results interestingly show a hierarchical ordered sequence of tangentially and radially oriented crystals into alternating polycrystalline layers. The layer width of the inner bands exactly matches with the optical inter-ring spacing (ca. 5 μm), proving emphatically that the interior lamellar assembly accurately accounts for the optical patterns of periodic rings. [ABSTRACT FROM AUTHOR]

In this research, the thermal properties and crystallization behavior of novel poly(hexamethylene succinate-co-6 mol% butylene succinate) (PHBS) and its homopolymer poly(hexamethylene succinate) (PHS) were extensively studied. With respect to PHS, the introduction of a small content of butylene succinate (BS) unit slightly reduces the melting point and equilibrium melting point but hardly influences the glass transition temperature of PHBS. Despite crystallization temperature, PHS and PHBS crystallize through the same crystallization mechanism. At the same crystallization temperature, PHBS crystallizes more slowly than PHS; furthermore, lowering crystallization temperature enhances the crystallization rates of PHBS and PHS. The spherulites morphologies were observed for both of them, with the spherulites nucleation density of the copolymer being smaller than that of the homopolymer. PHBS and PHS share the same crystal structures, indicative of the location of BS unit in the amorphous region. [ABSTRACT FROM AUTHOR]

Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of crystalline network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-crystalline polymers via micromechanical approaches. [ABSTRACT FROM AUTHOR]

We discuss how the “spherulites ring” morphology and “coffee ring” profile of PEO film formed by the drying droplet at glass substrate with different heating rate. Upon increasing the heating rate of substrate, it is found that deposited PEO film from drying droplet shows the unusually observed “coffee ring” profile and “spherulites ring” morphology. The main mechanism for this phenomenon is proposed to be an enhanced Marangoni convection which is induced by the increased solute concentration gradient and reduced viscous force above 70 °C. A simple formation mechanism of the unusually observed “coffee ring” profile and “spherulites ring” morphology is proposed. These findings can be exploited to trace the center of Marangoni convection, with potential applications in designing the spherulite patterns of crystalline polymer films in ink-jet printing and self-assembly fields. [ABSTRACT FROM AUTHOR]

The effects of flowing preformed spherulites on shear-induced melt crystallization behaviors of isotactic polypropylene (iPP) had been investigated by using a Linkam shearing cell coupled with an optical microscope, atomic force microscope, and rheometer. By quenching iPP melt to 130 °C for a short time, preformed spherulites were intentionally obtained. While iPP films were heated up to temperatures below the nominal melting point of iPP (164 °C), various shear conditions were applied, and then the crystalline morphologies during crystallization at the isothermal crystallization temperature of 135 °C were traced by alternately using phase contrast optical microscopy and polarized optical microscopy modes. Two distinct highly orientated thread- and cylinder-like crystalline morphologies were induced by shearing with preformed spherulites present, which were dependent on the applied shear rate and temperature. The distinct crystalline morphologies were attributed to relative movements between shear flowing melt and preformed spherulites. Atomic force microscopy was used to reveal the crystal aggregates of the two typical morphologies, indicating that the former was composed of highly packed orientated crystal nuclei, while the latter was composed of loosed packed random crystal nuclei, for which the thin crystal lamellae grew perpendicularly to crystal nuclei, leading to large widths for the cylinders as seen by an optical microscope. Rheological measurements indicated that preformed spherulites were isolated in the iPP films, which could obviously retard the stress relaxation of iPP films at the lower shear temperature. [ABSTRACT FROM AUTHOR]

l-Malic acid (LMA) is a commodity chemical that was first isolated in the crystalline form in the 18th century, yet it has been troublesome for more than 100 years because of its resistance to forming crystals that are suitable for optical or X-ray analysis. LMA crystallizations from the melt and from solutions are reevaluated here. Indeed, LMA crystallizes poorly from water. However, a flowable solid was produced by growth from ethyl acetate at room temperature to give large well-formed trapezoidal prisms of a new LMA polymorph, form II (space group P21, a = 5.7343(6) Å, b = 6.7990(7) Å, c = 6.9949(7) Å, β = 104.9610(10)°, V = 263.47(5) Å3, Z = 2). The growth of LMA from ethyl acetate at 4 °C produced hard, near-spherical aggregates of the only previously known phase, which also crystallizes in the space group P21 (form I). From the melt, LMA produces spherulites with helicoidal twisting of its individual fibrils. Polycrystalline ensembles are shown to arise from the inequivalent branching of the ends of a polar crystal which adopt semi-spherulitic morphologies as crystallization intermediates. Tailor-made additives were used to assign the absolute growth direction of the polar spherulite radii as +b. [ABSTRACT FROM AUTHOR]

The morphologies of poly(L-lactic acid) (PLLA) spherulites, when crystallized within the pre-existed poly(oxymethylene) (POM) crystal frameworks, have been investigated. PLLA/POM blend is a melt-miscible crystalline/crystalline blend system. Owing to the lower melting point but much faster crystallization rate than PLLA, POM crystallized first upon cooling from the melt state and then melted first during the subsequent heating process in this blend system. Lamellar assembly of PLLA crystals within the pre-existed POM spherulitic frameworks was directly observed with the polarized light microscopy by selectively melting the POM frameworks. The investigation indicated that PLLA crystals fully replicated the spherulitic morphology and optical birefringence of the POM crystal frameworks, which was independent of Tc. On the other hand, POM could also duplicate the pre-existed PLLA morphologies. The result obtained provides us a possibility to design the lamellar assembly and crystal structures of polymer crystals in miscible crystalline/crystalline polymer blends. [ABSTRACT FROM AUTHOR]

In order to investigate the role of thermo-oxidative aging on the crystal structure of crosslinked polyethylene (XLPE) at temperatures below and above the melting point, thermo-oxidative aging was conducted on XLPE cable insulation at 100, 120, 140 and 160 °C respectively. The crystal structure of the fresh sample and aged samples was characterized by X-ray diffraction, differential scanning calorimetry (DSC) and scanning electron microscopy tests. The concentration of antioxidants in XLPE samples was measured by the DSC method. It was deduced by the obtained results that the thermo-oxidative aging process could be divided into the physical aging stage and the chemical aging stage depending on the concentration of antioxidants in XLPE. In the physical aging stage, re-crystallization process led to the improvement of crystal structure and the increase in crystallinity. In the chemical aging stage, the breakage of intramolecular and intermolecular bonds led to drastic chains scission, resulting in the decrease in crystallinity. At 100 °C, the thermo-oxidative aging mainly affected the amorphous regions and had a limited effect on the crystalline regions. At 120, 140 and 160 °C, the thermo-oxidative aging affected the molten spherulites, resulting in decreased lamellae, increased lamellar spacing and the destruction of spherulites. [ABSTRACT FROM AUTHOR]

Polyamide 6 (PA6), also known as Nylon 6 is a widely used industrial polymer. The structural properties of PA6 play an important role in its potential commercial applications. We report that the anionic polymerization of ε-caprolactam in the presence of liquid additives such as o-Xylene, m-Xylene, p-Xylene and toluene at a critical concentration led to the formation of high crystalline, porous polyamide 6 (aPA6). Porous aPA6 samples possess hierarchical spherulitic morphology where 10 μm size spherulitic granules are interconnected by submicron size fibrillated domains. The size and shape of spherulitic domains change with the type of liquid additives used during the synthesis of porous aPA6. The presence of liquid additives influences the kinetics of the exothermal processes during polymerization, which ultimately leads to a solid-liquid phase separation prior to the formation of porous networks of spherulites. Such process also leads to thickening of lamella and formation of second order crystals that contributed to highest crystallinity in porous aPA6 ever reported. Differential scanning calorimetric along with wide-angle X-ray scattering study reveal ∼60% crystallinity in all porous aPA6, which is about 60% increase in comparison with the neat aPA6 (∼40%). Higher crystallinity in porous aPA6 also exhibited 50% reduction in moisture uptake in comparison with the neat aPA6. [ABSTRACT FROM AUTHOR]

This article reports on synthesis and spectroscopic characterizations of surface crystallized BaB 4 O 7 nanocrystals doped with Sm and Sm:Yb rooted in borate glass which forms microsized ‘Spherulites’ while annealing for more than 06 h. Detailed nano and microstructural analysis were done using transmission, scanning electron microscopic and Polaroid optical microscope images; and XRD techniques which revealed the formation of cone - shaped BaB 4 O 7 spherulites. Images under polarized light revealed birefringence property in tiny crystals rooted in glass- ceramic. A bright red dominated orange-red emission was observed under UV (266 nm) laser excitations. Emission intensity was found to be 08 multiple, in ceramics, then the glass counterpart. Formation of tiny crystals reinforces sharp emission peaks (FWHM ~ 1.6 nm) due to Sm 3+ ions. We have confirmed formation of Yb 2+ , Yb 3+ and Sm 3+ ionic species in the lattice which leads infrared cascade downconversion emissions spanning in the wide range of 380–1000 nm through involvement of intervalence charge transfer from Yb 2+ to Yb 3+ ions. [ABSTRACT FROM AUTHOR]