Faster Crystallization Rate Research Articles

Crystallization‐correlated phase separation of polypropylene random copolymers

AbstractEthylene segments are incorporated into stereoregular propylene‐propylene‐propylene (PPP) homo‐sequences to create locally disordered ethylene‐propylene (EP) segments in polypropylene random copolymer (PPR) through a phase separation process, resulting in large quantities of spherical EP rubbery particles for improving impact toughness. However, the manipulation on size and distribution of these spherical EP rubbery phases remains insufficiently understood. In this study, the phase separation of PPR and the influence of crystallization on phase separation were investigated using rheological measurements and small‐angle x‐ray scattering (SAXS) methods. Combined with the isothermal crystallization method, phase separation was differentiated by the crystallization rate. The molecular chain states corresponding to different crystallization conditions were studied to interpret the varying rubbery particle sizes resulting from phase separation. The results showed that phase separation of EP segments from PPP is highly related to crystallization. Isothermal crystallization at temperatures ranging from 110 to 130°C leads to a high degree of phase separation due to the fast crystallization rate, as evidenced by the presence of small quantities of large pores in microscopic observations. This work provides insights into the phase separation of random copolymers and establishes correlations for manipulating the low‐temperature toughness of PPR.

Significantly enhanced crystallization of poly(L‐lactide) by incorporation of poly(D‐lactide) grafted cellulose nanocrystals

AbstractPoly(L‐lactic acid) (PLLA), as a green, biodegradable polymer material, has garnered considerable attention due to its ease of processing and exceptional properties. However, the inherent slow crystallization rate and brittleness of PLLA substantially restrict its extensive applications across various domains. In present work, PLLA and poly(D‐lactide) (PDLA)‐modified cellulose nanocrystals (CNCs), referred as CNC‐g‐L and CNC‐g‐D, are serving as nano‐fillers to enhance the crystallization rate of PLLA. Our findings demonstrate that both nano‐fillers could enhance the crystallization rate of PLLA, but the CNC‐g‐D shows a more efficient nucleation agent compared with its counterpart, CNC‐g‐L. Isothermal crystallization analysis indicates that CNC‐g‐D substantially increases nucleation density of PLLA, with pronounced crystallization at an elevated temperature of 155°C as confirmed by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Wide‐angle x‐ray diffraction (WAXD) analysis shows the preformation of stereocomplex crystals on the CNC‐g‐D surface may result in a fast crystallization rate. Meanwhile, after incorporation of different nano‐fillers, the toughness property of PLLA has also been significantly enhanced. Our result has shown the CNC‐g‐D could serve as an efficient nucleation agent toward PLLA and also facilitate to aiding in establishing comprehensive structure–property relationships of polymer materials.

Effect of Nano Spinel Ferrites Co0.9Cu0.1Fe2O4 on Non-Isothermal Cold Crystallization Behaviours and Kinetics of Its Composites with Polylactic Acid.

Nanoparticles of spinel ferrites with a composition of Co0.9Cu0.1Fe2O4 (AM NPs) were effectively synthesized via a hydrothermal route. The structure of ferrite nanoparticles was characterized with X-ray diffraction, which showed a single cubic spinel phase. Energy-dispersive X-ray (EDX) spectroscopy and field emission-scanning electron microscopy (FE-SEM) were employed to analyse elemental composition and surface morphology, respectively. Moreover, the effects of the Co0.9Cu0.1Fe2O4 on the morphology of [PLA = polylactic acid] nanocomposites were examined through polarized light optical microscopy (POM) and X-ray diffraction (XRD). The thermal behaviours for tested samples were studied through [DSC = differential scanning calorimetry] and [TGA = thermal gravimetric analysis]. A great number of minor PLA spherulites were detected using POM in the presence of the Co0.9Cu0.1Fe2O4 ceramic magnetic nanoparticles (AM), increasing with AM nanoparticle contents. X-ray diffraction (XRD) analysis showed that the presence of nanoparticles led to an increase in the intensity of diffraction peaks. The DSC findings implied that the crystallization behaviours for the efficient PLA as well as its nanocomposites were affected by the addition of AM nanoparticles. They act as efficient nucleating agents because they shift the temperature of crystallization to a lower value. The Avrami models were used to analyse kinetics data. The experimental data were well described using the Avrami method for all samples tested. The addition of AM to the PLA matrix resulted in a decrease in the crystallization half-time t1/2 values, indicating a faster crystallization rate. TGA data showed that the occurrence of AM nanoparticles decreased the thermal stability of PLA.

Efficient Tin-Based Perovskite Solar Cell with a Cesium Acetate Pre-buried PEDOT:PSS Hole Transport Layer.

The strong Lewis acid tin halide leads to an excessively fast crystallization rate, resulting in more defects in the film and degraded device performance. In this work, a cesium acetate (CsAc) pre-buried poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transport layer acts as nucleation points during the crystallization of tin-based perovskite, which can induce preferential orientation growth of crystals and increase the grain size to improve the quality of crystallization. The addition of CsAc not only can increase the conductivity of PEDOT:PSS but also can improve the wettability of the perovskite precursor solution to enhance the interface contact between the hole transport layer and perovskite layer. Because of the incorporation of CsAc in PEDOT:PSS, the average short-circuit current density increases from 23.80 to 27.60 mA cm-2. Furthermore, a power conversion efficiency of 10.99% is achieved for a tin-based perovskite solar cell with CsAc-doped PEDOT:PSS as the hole transport layer.

Effect of Tween 20, emulsification temperature and ultrasonication intensity on structured emulsions with monoglycerides

Structured emulsions are regarded as an innovative way to replace saturated fat in food products. Monoglycerides (MGs) as lipid-based surfactants could form mainly water-in-oil emulsions, which tend to phase separate. The aim of this study was to investigate the interaction of Tween 20 (0–6% w/w) in 3% (w/w) MGs-based emulsions, under various emulsification temperatures (−3–70 °C) and various ultrasonication intensities. Several analytical methods such as differential scanning calorimetry, confocal and polarized optical microscopy and rheometry were employed to characterize the structured systems. The presence of Tween 20 promoted the formation of oil-in-water structured emulsions and prevented the droplet coalescence and phase separation. The emulsification at low temperatures accelerated the secondary crystallization of the MGs to the coagel state, promoted the preference of the crystals to be located at the interface of the oil droplets and act as Pickering particles. The formed free-standing emulsion gels showed improved stability under freeze-thaw cycling. High ultrasonication intensities during emulsification formed firmer gels with fast crystallization rates, while at low intensities the coagel crystallization was delayed. The MGs/Tween 20 formed needle-like crystals in water, which were employed as Pickering type emulsifiers to form oil-in-water structured emulsions. The MGs/Tween 20 structured emulsions showed improved stability than the conventional emulsions, indicating that they could be utilized as animal fat substitute systems in plant-based alternative food products, as well as in cosmetic and pharmaceutical applications.

Enhancing the Performance of 2D Tin-Based Pure Red Perovskite Light-Emitting Diodes through the Synergistic Effect of Natural Antioxidants and Cyclic Molecular Additives.

Tin (Sn)-based perovskites are being investigated in many optoelectronic applications given their similar valence electron configuration to that of lead-based perovskites and the potential environmental hazards of lead-based perovskites. However, the formation of high-quality Sn-based perovskite films faces several challenges, mainly due to the easy oxidation of Sn2+ to Sn4+ and the fast crystallization rate. Here, to develop an environmentally friendly process for Sn-based perovskite fabrication, a series of natural antioxidants are studied as additives and ascorbic acid (VitC) is found to have a superior ability to inhibit the oxidation problem. A common cyclic molecule, 18-Crown-6, is further added as a second additive, which synergizes with VitC to significantly reduce the nonradiative recombination pathways in the PEA2SnI4 film. This synergistic effect greatly improves the performance of 2D red Sn-based PeLED, with a maximum external quantum efficiency of 1.87% (≈9 times that of the pristine device), a purer color, and better bias stability. This work demonstrates the potential of the dual-additive approach in enhancing the performance of 2D Sn-based PeLEDs,while the use of these environmentally friendly additives contributes to their future sustainability.

Preparation of wide-bandgap perovskite thin films by propylamine hydrochloride assisted gas quenching method

Perovskite is a material with excellent photovoltaic properties, and the efficiency of perovskite solar cells has increased rapidly in recent years. By utilizing the adjustable bandgap characteristics of perovskite materials, wide-bandgap perovskite solar cells can be combined with narrow-bandgap solar cells to make tandem solar cells. Tandem devices can improve the utilization of the solar spectra and achieve higher power conversion efficiency. An important prerequisite for preparing efficient photovoltaic devices is to fabricate high-quality perovskite active layers. Antisolvent-assisted spin-coating is currently a commonly used method for preparing high-quality perovskite films in the laboratory. However, the low solubility of inorganic cesium and bromine salts in the preparation of wide-bandgap perovskite thin films leads to a fast crystallization rate, poor crystallization quality and a large number of defects, seriously reducing the photovoltaic performance of the devices. In addition, the antisolvent has a narrow working window, which is not conducive to the preparation of large-area perovskite films. In this work, a mild gas quenching process is used to assist the spin-coating method in preparing wide-bandgap perovskite films, and propylamine hydrochloride is introduced as an additive to improve the crystallization quality and uniformity of large-area preparation of perovskite film. The interaction between the propylamine cation and the perovskite component produces a two-dimensional perovskite phase. Two-dimensional phase is used as the growth template for perovskite composition in order to reduce the formation energy of <i>α</i>-phase perovskite, which is beneficial to uniform nucleation and preferential orientation growth of perovskite, the increase of grain size and the decrease of grain boundaries within the film. The improvement of the crystalline quality of the perovskite film can reduce the defect density inside the film and suppress the non-radiative recombination of the photogenerated carriers. The perovskite solar cell with a bandgap of 1.68 eV, prepared by using this strategy, achieves a power conversion efficiency of 21.48%. In addition, the 8 cm×8 cm wide-bandgap perovskite films prepared by this method exhibit good uniformity. This work provides a strategy for developing the process of efficient and large-area perovskite photovoltaic devices.

Ligand Engineering Enables Efficient Pure Red Tin-Based Perovskite Light-Emitting Diodes.

With increasing ecological and environmental concerns, tin (Sn)-based perovskite light-emitting diodes (PeLEDs) are competitive candidates for future displays because of their environmental friendliness, excellent photoelectric properties, and low-cost solution-processed fabrication. Nonetheless, their electroluminescence (EL) performance still lags behind that of lead (Pb)-based PeLEDs due to the fast crystallization rate of Sn-based perovskite films and undesired oxidation from Sn2+ to Sn4+ , leading to poor film morphology and coverage, as well as high density defects. Here, we propose a ligand engineering strategy to construct high-quality phenethylammonium tin iodide (PEA2 SnI4 ) perovskite films by using L-glutathione reduced (GSH) as surface ligands toward efficient pure red PEA2 SnI4 -based PeLEDs. We show that the hydrogen-bond and coordinate interactions between GSH and PEA2 SnI4 effectively reduce the crystallization rate of the perovskites and suppress the oxidation of Sn2+ and formation of defects. The improved pure red perovskite films not only show excellent uniformity, density, and coverage but also exhibit enhanced optical properties and stability. Finally, state-of-the-art pure red PeLEDs achieve a record external quantum efficiency of 9.32 % in the field of PEA2 SnI4 -based devices. This work demonstrates that ligand engineering represents a feasible route to enhance the EL performance of Sn-based PeLEDs.

Ligand Engineering Enables Efficient Pure Red Tin‐Based Perovskite Light‐Emitting Diodes

AbstractWith increasing ecological and environmental concerns, tin (Sn)‐based perovskite light‐emitting diodes (PeLEDs) are competitive candidates for future displays because of their environmental friendliness, excellent photoelectric properties, and low‐cost solution‐processed fabrication. Nonetheless, their electroluminescence (EL) performance still lags behind that of lead (Pb)‐based PeLEDs due to the fast crystallization rate of Sn‐based perovskite films and undesired oxidation from Sn2+ to Sn4+, leading to poor film morphology and coverage, as well as high density defects. Here, we propose a ligand engineering strategy to construct high‐quality phenethylammonium tin iodide (PEA2SnI4) perovskite films by using L‐glutathione reduced (GSH) as surface ligands toward efficient pure red PEA2SnI4‐based PeLEDs. We show that the hydrogen‐bond and coordinate interactions between GSH and PEA2SnI4 effectively reduce the crystallization rate of the perovskites and suppress the oxidation of Sn2+ and formation of defects. The improved pure red perovskite films not only show excellent uniformity, density, and coverage but also exhibit enhanced optical properties and stability. Finally, state‐of‐the‐art pure red PeLEDs achieve a record external quantum efficiency of 9.32 % in the field of PEA2SnI4‐based devices. This work demonstrates that ligand engineering represents a feasible route to enhance the EL performance of Sn‐based PeLEDs.

Direct relationship between crystalline structure and part deformation of polypropylene copolymer parts fabricated by material extrusion additive manufacturing

AbstractThe high crystallinity and fast crystallization rate of polypropylene (PP) often result in severe warpage of final parts prepared by means of material extrusion additive manufacturing (MEAM). In this work, the effect of bed temperature (Tb) and nozzle temperature (Tn) on the dimensional accuracy and mechanical property of MEAM‐printed PP copolymer parts was investigated. It is found that raising Tb and Tn could significantly reduce the warpage of PP parts by regulating the crystallization behavior of PP. Specially, the amount of γ‐crystal grows obviously while the total crystallinity remains unchanged, as Tb or Tn increases. Moreover, the more the content of γ‐crystal, the lower the warpage height of PP samples is. Hence, a close correlation between the content of γ‐crystal and part deformation of MEAM‐printed PP parts is successfully established. This is mainly related to the large rigidity of γ‐crystal, which significantly reduces the volume shrinkage of PP during MEAM process. Besides, the raise of Tb or Tn also enhances the tensile strength, modulus and the elongation at break of PP parts. This wok provides an effective and convenient method for the manufacture of PP parts with good dimensional accuracy and excellent mechanical properties by means of MEAM techniques.

The fragile-to-strong kinetics features of two-dimensional confined ultrathin Ag-In-Sb-Te film

The crystallization kinetics of supercooled Ag-In-Sb-Te liquids (in thick single film) has recently been shown to exhibit a fragile-to-strong crossover (FSC) behavior, which is beneficial to balance the contradiction between fast crystallization rate around the melting temperature (Tm) and good thermal stability (low crystallization rate) nearby the glass transition temperature (Tg). In this work, we fabricated an ultrathin Ag-In-Sb-Te film (∼7 nm) that is confined in a 2D structure. Does this confined ultrathin film exhibit FSC behavior? Focusing on this issue, we studied the crystallization features of 2D confined Ag-In-Sb-Te ultrathin film by using the method of ultrafast differential scanning calorimetry and the viscosity model of generalized Mauro-Yue-Ellison-Gupta-Allan. It was found that, the FSC behavior is presented and enhanced in this confined Ag-In-Sb-Te film. Interestingly, the FSC temperature of this confined Ag-In-Sb-Te is 473 K (∼1.25 Tg), which is equal to that of thick single Ag-In-Sb-Te film, indicating the structural origins of FSC behavior are same in these Ag-In-Sb-Te supercooled liquids, i.e., the FSC behavior stems from liquid-liquid phase transition that is predominantly caused by the increase of Peierls distortions with the competition between short range and medium range cluster. This reveals the crystallization features of ultrathin Ag-In-Sb-Te film, enabling a systematic optimization of the memory-switching kinetics in low-dimensional phase-change device.

Reevaluation of the Crystallization Kinetics of Precisely Synthesized, Discrete Oligo(γ-butyrolactone)s

The crystallization behavior of polymers has always been an important part of polymer physics. The data from a previous paper, “Crystallization Kinetics of Precisely Synthesized Discrete Oligo(γ-butyrolactone)s” published in Acta Polymerica Sinica (2022), are further discussed here in order to clarify some issues which could easily be confused. We show here that the crystallization process was affected not only by the molecular weight, but also by the end group. In the case of oligo(γ-butyrolactone)s, the crystallization rate was restrained by the end group, t-butyl diphenyl silicon, within the oligomer chain due to its different structure from the repeat unit and its steric effect. As the content of the end groups was relatively high for the lower molecular weight, the crystallization was inhibited. With the increasing molecular weight, the influence of the end groups decreased. Since the content of the end group t-butyl diphenyl silicon was below 10 wt%, the crystallization rate with higher molecular weight was slower than that with lower molecular weight, similar to the general rule. In the case of polydisperse oligomers with relatively high molecular weight, the components with not too low molecular weight which crystallization would not be affected by the terminal groups, such as the components with 32 structural units, would make a greater contribution to the crystallization process resulting in faster crystallization rate, rather than those with higher molecular weight than the average molecular weight.

Optimization of Mold Slag for Continuous Casting of Peritectic Steel

To reduce the occurrence of stickers and longitudinal cracks during continuous casting (CC) of peritectic steel, herein, the use of a mold slag with high basicity and adequate lubrication is proposed. Laboratory results indicate that the mold slag with a basicity of 1.75 and 2.3 wt% Li2O content exhibits a lower break and melting temperatures and relatively fast crystallization rate. The proposed mold slag can rapidly induce crystallization to control the heat flux, and the residual flux after crystallization and formation of the solid slag still exhibits excellent lubrication on the initial shell. Thus, coordination control of heat transfer and lubrication during CC of peritectic steel can be achieved. Industrial trials obtain satisfactory results, the application of the designed mold slag reduces the occurrence of stickers, and longitudinal cracks are reduced at the initial stage of one sequence casting.

Solid-State Synthesis of Aluminophosphate Zeotypes by Calcination of Amorphous Precursors

Because of the growing interest in the applications of zeolitic materials and the various challenges associated with traditional synthesis methods, the development of novel synthesis approaches remains of fundamental importance. Herein, we report a general route for the synthesis of aluminophosphate (AlPO) zeotypes by simple calcination of amorphous precursors at moderate temperatures (250-450 °C) for short reaction times (3-60 min). Accordingly, highly crystalline AlPO zeotypes with various topologies of AST, SOD, LTA, AEL, AFI, and -CLO, ranging from ultra-small to extra-large pores, have been successfully synthesized. Multinuclear multidimensional solid-state NMR techniques combined with complementary operando mass spectrometry (MS), powder X-ray diffraction, high-resolution transmission electron microscopy, and Raman characterizations reveal that covalently bonded fluoride in the intermediates catalyze the bond breaking and remaking processes. The confined organic structure-directing agents with high thermal stability direct the ordered rearrangement. This novel synthesis strategy not only shows excellent synthesis efficiency in terms of a simple synthesis procedure, a fast crystallization rate, and a high product yield, but also sheds new light on the crystallization mechanism of zeolitic materials.

Effects of PDLA molecular weight on the crystallization behaviors and rheological properties of asymmetric PDLA/PLLA blends

The molecular weight of poly(d-lactide) (PDLA) and poly(l-lactide) (PLLA) affects the performance of their blends by controlling the formation and characteristics of stereocomplex (SC) crystals. In this work, the crystallization behaviors and rheological properties of asymmetric PDLA/PLLA (5/95, w/w) blends were carefully investigated considering the molecular weight of PDLA (Mn(PDLA) = 1.5 × 103–18.7 × 103 g/mol) when the molecular weight of PLLA was selected as 5.0 × 104 g/mol. The results revealed that PDLA holding too low or too high Mn(PDLA) was unfavorable to the formation of SC crystallites owing to their weak interaction or difficult diffusion in the PLLA matrix, and the optimal Mn(PDLA) was ca.5.4 × 103 g/mol. Given this optimal Mn(PDLA), the composite viscosity and tensile viscosity of the obtained PDLA/PLLA blend were increased by 2–3 orders of magnitude and 10 times compared with neat PLLA, respectively, due to the formation of SC crystals with a high content (ΔHm-SC of 26.0 J/g). Besides, this PDLA/PLLA blend showed a fast crystallization rate and strong solid-like viscoelastic behavior. This work revealed the regular correspondence between Mn(PDLA) and the performance of asymmetric PDLA/PLLA blends.

Large organic cations are beneficial for slowing tin-based perovskites crystallization rate and improving efficiency

In the past few years, the efficiency of perovskite cells has been improved rapidly, and the current efficiency can reach 25.8%. Since the lead in perovskite materials will pollute the environment, so people turn their attention to lead-free tin-based perovskites. Tin-based perovskites are becoming a research hotspot recently due to their nontoxic properties. However, due to the fast crystallization rate of tin-based perovskite, the improvement of the efficiency of tin-based perovskite cells is limited. In this work, by introducing ethylammonium iodine (EAI) into FA0.98SnI3 perovskite, it not only slowed down the crystallization rate of tin-based perovskite cells, but also improved the film morphology and slowed down the rate of Sn2+ oxidation, and finally achieved a solar cell conversion efficiency of 7.6%. This work provides a new strategy for the study of lead-free perovskites.

Combining solid state grinding and steam-assisted crystallization for green organotemplate-free synthesis of ZSM-5

Green synthesis of zeolite has been made much progress due to solvent-free grinding methods. Although solid-state synthesis is a simple green process with a high yield, its kinetics of the solid-phase crystallization process is still slow and the precursor materials are not uniformly heated throughout the reactor resulting into the poor uniformity of the particles. Herein, we report a high-efficiency organotemplate-free synthesis of ZSM-5 combining solid state grinding and steam-assisted crystallization. Solid state grinding (SSG) of aluminosilicate precursor avoids usage of solvent and steam-assisted conversion (SAC) in an organic-template-free condition grants a fast crystallization rate of ZSM-5. More importantly, the vapor fulfilled in the reactor ensures uniform heating of solid feedstock for crystallization of ZSM-5, leading the high crystallinity and the uniform particle size distribution. This combination can guarantee 100% relative crystallinity of ZSM-5 in 12 h, compared to that of 80% crystallinity from sole solid state at the same crystallization temperature (180 °C). Furthermore, this combination can achieve 83% relative crystallinity of ZSM-5 at 160 °C, compared to that of 37% crystallinity from the solid state alone. Highly dispersed ZSM-5 zeolite with adjustable SiO2/Al2O3 ratio is prepared by steam-assisted crystallization of grinding solid raw materials. The catalytic activity of ZSM-5 catalyst from this combination strategy for the acetalization of cyclohexanone is superior to that of the solid-state method alone. This sustainable and green synthesis method provides a potential way for the preparation of zeolites in an industrial scale.

The Influence of Metal Lithium and Alkyl Chain in the Nucleating Agent Lauroyloxy-Substituted Aryl Aluminum Phosphate on the Crystallization and Optical Properties for iPP

In this work, a kind of aryl phosphate salt nucleating agent (APAl-12C) was synthesized, which was replaced in the hydroxyl group on the aluminum hydroxy bis [2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] (APAl-OH) by lauroyloxy, which could improve the dispersion between the nucleating agent and the iPP matrix and reduce the migration potential of the nucleating agent in the iPP matrix by increasing the molecular weight. The structure of the nucleating agent APAl-12C was analyzed by fourier infrared spectroscopy (FT-IR ) and 1H NMR. The differential scanning calorimeter (DSC) results indicated that the addition of APAl-OH or APAl-12C alone was inferior to the commercial nucleating agent NA-21 (compounds of APAl-OH and Lithium laurate) in terms of the crystallization behavior, which may be due to the importance of metal Li in the crystallization property. Thus, the iPP/A12C-Li composites were prepared with APAl-12C, lithium laurate (lilaurate) and the iPP matrix. The crystallization behavior, morphology, optical and mechanical properties for the iPP/A12C-Li composites were systematically studied and compared with that of the iPP/NA-21 composite. Among the iPP/A12C-Li composites with the addition of 0.5 wt%, APAl-12C/Lilaurate had the fastest crystallization rate and reduced the haze value of the neat iPP from 36.03% to 9.89% without changing the clarity, which was better than that of the iPP/NA-21 composite. This was due to the weakening of the polarity of the APAl-12C after lauroyloxy substitution and better dispersion in the iPP matrix, resulting in a significant improvement in the optical properties.

Physical properties of oleogels fabricated by the combination of diacylglycerols and monoacylglycerols

AbstractOleogelation is an efficient way to offer healthy substitutes for trans and saturated fatty acids in processed foods. Multicomponent gels are of particular interest due to the ability to tune gel properties by altering the component proportions. In this study, monoacylglycerol (MAG) and diacylglycerol (DAG) are used as gelator blends and the influence of the gelator ratio on the characteristics of oleogels was investigated. The crystallization and melting behavior, solid fat content (SFC), crystal morphology, polymorphism and mechanical properties of the oleogels were characterized. The oleogels with higher gelator level displayed increased oil binding ability and shorter crystal formation time. The oleogels with higher MAG ratio exhibited more fibrillar‐like crystals, and the mixed oleogels with MAG:DAG of 5:5 showed altered crystal morphology with finer crystal size, reduced crystallization enthalpies and solid state possibly due to the increased nucleation seeds promoted by MAG. The oleogels with high MAG level showed lower equilibrium SFC during isothermal crystallization but faster crystallization rate, higher hardness and elasticity. Therefore, by changing the ratio of DAG to MAG, the crystallization profile and rheological properties of oleogels can be tailored. The oleogels can be used as traditional solid fat substitutes to reduce saturated fatty acid content in lipid‐based products.

Biobased Poly(ethylene succinate)-b-poly(triethylene terephthalate) multiblock copolyesters with high melting temperature and improved crystallization rate and mechanical property

Biobased poly(ethylene succinate)- b -poly(triethylene terephthalate) (PES -b- PTEGT) multiblock copolyesters with low weight ratios of PTEGT segment were successfully synthesized from dihydroxyl terminated PES and dihydroxyl terminated PTEGT prepolymers in this work through a chain extension reaction. The thermal, crystallization, and mechanical properties of PES -b- PTEGT were systematically investigated and compared with those of PES also prepared via the chain extension method. Two glass transition temperature ( T g ) values were detected for PES -b- PTEGT, corresponding to the T g of PES segment and that of PTEGT segment, respectively. PES -b- PTEGT showed a high melting temperature of around 100 °C and a thermal decomposition temperature of above 320 °C. The crystallizability of PES segment in PES -b- PTEGT was obviously enhanced under different crystallization conditions, which was attributed to the interface-assisted crystallization. In addition, the mechanical property (including both the elongation at break and the tensile strength) of PES -b- PTEGT was also remarkably improved. The synthesis of PES -b- PTEGT with a high melting temperature, faster crystallization rate, and improved mechanical property provided a new modification method to improve the physical property and extend the practical application of biodegradable polyesters. • Biobased PES -b- PTEGT copolyesters were synthesized via a chain extension reaction. • PES -b- PTEGT showed a high T m of around 100 °C and a T d of above 320 °C. • The crystallizability of PES segment in PES -b- PTEGT was obviously enhanced. • The mechanical property of PES -b- PTEGT was also remarkably improved. • This research proposed a novel method to modify the physical properties of PES.