Melt Crystallization Process Research Articles

Enhancing the stereocomplex crystallization of PLLA/PDLA symmetric blend by controlling the degree of molecular chain entanglement

In order to enhance the content of stereocomplex crystals (SC) in poly l-lactic acid (PLLA)/poly d-lactic acid (PDLA) symmetric blend, thereby improving the defects of low crystallinity and poor heat resistance of polylactic acid (PLA)-based materials, the samples with different entanglement degrees were prepared by freezing extration method. The critical overlap concentration of the blend system was quantitatively obtained using an Ubbelohde viscometer. Based on this concentration, samples with a series of concentration gradient were prepared to control the different degrees of molecular chain entanglement inside. The results indicated that the chain disentanglement could greatly increase the content of SC in the blend, whether in the precipitation crystallization or the melt crystallization process. Especially after the isothermal crystallization for 30min at 130 °C, the L/D-0.1 sample with the highest degree of disentanglement almost only formed SC, accounting for 95.2 % of the total crystallinity. Samples with lower entanglement degree had more crystal nuclei and faster growth rate of formed spherulites. For completely entangled sample L/D-50, the crystal nucleus of homo-crystalls (HC) could be considered as SC. Besides, the Vicat softening temperature (VST) of L/D-0.1 sample increased from 79.9 °C of L/D-50 sample to 103.8 °C with an obvious increase of 24.9 °C. All these results provide new ideas for improving the performance of PLA-based materials and show promising development prospects of green and sustainable polymers.

Enhancing energy storage performance of dielectric capacitors: Tailoring CaO-SrO-Na2O-Nb2O5-SiO2 glass-ceramics through controlled crystallization for pulse power applications

As potential dielectric materials for capacitors, glass-ceramics exhibit significant promise in the realm of pulse power supply. Extensive research has been undertaken to explore the commendable voltage resistance and favorable dielectric properties of glass-ceramics. They exhibit a rapid charge and discharge rate. However, the limited energy storage density of glass-ceramics constrains their practical application. In this study, we focused on the preparation of CaO-SrO-Na2O-Nb2O5-SiO2(CSNNS) glass-ceramics through conventional melting and high-temperature crystallization processes. Our investigation delved into the impact of crystallization temperature on the phase composition, dielectric properties, and energy storage characteristics of the CSNNS glass-ceramics. The results indicate a direct correlation between the dielectric constant and dielectric loss, both exhibiting an upward trend with increasing crystallization temperature. Simultaneously, the microstructure of the glass-ceramics manifests signs of deterioration, characterized by larger grain size and heightened porosity, leading to a reduction in breakdown strength. At a crystallization temperature of 1100 °C, the CSNNS glass-ceramics demonstrated a remarkable combination of a high dielectric constant (∼280) and superior breakdown strength (481 kV/cm). The achieved maximum theoretical energy storage density reached 2.87 J/cm3. At an electric field of 100 kV/cm, the effective energy storage density is 0.23 J/cm3, and the energy storage efficiency is 72 %. These findings demonstrate the broad application potential of the CSNNS glass-ceramics in the domain of pulse power, highlighting their relevance for future developments in this field.

Geochemical and geochronological evidences from Cambrian to Ordovician protracted magmatism in the Istranca Massif, NW Türkiye

Plutonic rocks in different ages are cropted out and form the basement rocks in the Istranca Massif. One of the plutons located at the basement is the Cambrian-Ordovician Vize pluton (Vize-Kırklareli) and is distinguished from other plutons by some of its characteristic features. This pluton intruded into the high-grade metamorphic sedimentary rocks, and is unconformably overlay by Triassic low-grade metamorphic rocks and Eocene aged coral reef limestones (Soğucak Formation). Based on new whole rock geochemical and zircon UPb data concentrated in two different ages, it can be said that the Vize pluton was affected by protracted magmatic activity. The igneous minerals and texture of Vize pluton are partly preserved, It has a mylonitic texture, a distinct foliation consisting of light and dark zones. In addition, metagranites contain mafic magmatic enclaves (MMEs) in some places.The Vize pluton is an I-type pluton with predominantly peraluminous and slightly metaluminous character. It is also High-K, calc-alkaline, and reflecting volcanic arc and post-collisional tectonic settings. Mineral chemical analyses show that the mafic minerals in the Vize pluton consist of Fe-biotite and calcic amphibole (hornblende). Ti-in biotite thermometry shows that the temperature of the pluton in the final crystallization temperatures are between 834 and 850 °C (mean = 845 ± 4 °C), while the crystallization temperatures of amphiboles are between 876 and 910 °C (mean = 893 ± 22 °C). Crystallization depths are estimated to be a range of 6.5 to 7.9 km. It can be assumed that the oxygen fugacity of calcic amphiboles (logƒO2) is stabilized between −10.7 and − 11.3 bar (mean = −11.05 ± 0.4 bar). ∆NNO values are between 0.72 and 1.11 (mean = 0.96 ± 0.12) and H2O melt content is between 4.63 % and 5.43 % (mean = 5.04 ± 0.4 %). Oxygen fugacity values are among the typical values of calc-alkaline magma crystallization.The Vize pluton was crystallized in Cambrian to Ordovician times according to zircon UPb dating is concentrated in two different populations as 526.16 ± 3.26 Ma and 452.93 ± 2.76 Ma. All data obtained are consistent with the ages of the magmatism that produced the Vize Pluton in the Balkanides and Istranca Massif of 420–470 Ma (mean 447.17 ± 3.24 Ma) and indicate that it probably formed in the northern Gondwana. It was affected by the magma-mixing processes of coeval felsic and mafic magmas, and anatexis processes. Geochronological and geochemical data indicate the existence of a protracted magmatic activity related to convergent setting (long-lived magmatic arc) that forced the Vize-Pluton to undergo multi-stage melting-crystallization processes.

Crystallization Behavior and Mechanical Property of Biodegradable Poly(butylene succinate-co-2-methyl succinate)/Cellulose Nanocrystals Composites.

Biodegradable poly(butylene succinate-co-2-methyl succinate) (PBSMS)/cellulose nanocrystals (CNC) composites were successfully prepared at low CNC loadings with the aims of improving crystallization and mechanical properties and extending the practical application of PBSMS. CNC is finely dispersed in the PBSMS matrix without obvious aggregations. The low content of CNC obviously promoted the crystallization behavior of PBSMS under different conditions. The spherulitic morphology study revealed that CNC, as an effective heterogeneous nucleating agent, provided more nucleation sites during the melt crystallization process. In addition, the nucleation effect of CNC was quantitatively evaluated by the following two parameters, i.e., nucleation activity and nucleation efficiency. The crystal structure and crystallization mechanism of PBSMS remained unchanged in the composites. In addition, as a reinforcing nanofiller, CNC significantly increased Young's modulus and the yield strength of PBSMS. The crystallization behavior and mechanical properties of PBSMS were significantly improved by the low content of CNC, which should be interesting and essential from the perspective of biodegradable polymer composites.

Dramatically Accelerating II-I Crystal Phase Transition of Polybutene‑1 by In Situ Incorporation of H-Shape Long-Chain-Branching Structures.

This communication reports an effective strategy helping address the long-troubling melt processing issue of isotactic polybutene-1 (i-PB) caused by its extremely slow II-I crystal phase transition. The solution lies in a facile synthesis of i-PB containing H-shape long-chain-branching structures (LCB-i-PB) by applying a so-called ω-alkenylmethyldichlorosilane copolymerization-hydrolysis (ACH) chemistry to butene-1 polymerization with Ziegler-Natta or metallocene catalysts. It is evident that the H-shape LCB structures effectively enhance chain entanglements of i-PB and induce an over-the-board acceleration of the overall melt crystallization process including nucleation, form II crystallization, and form II-form I phase transition. As i-PB usually requires up to a week to reach equilibrium of the II-I phase transition, it is found that with LCB-i-PB such a transition is almost finished within as short as 24 h to even higher degrees.

Partial melting mechanisms of peraluminous felsic magmatism in a collisional orogen: An example from the Khondalite belt, North China craton

AbstractSedimentary‐derived (S‐type) granites are an important product of orogenic metamorphism, and a range of subtypes can be recognized by differences in field occurrence, mineralogy and geochemistry. These subtypes can reflect variations of initial protolith composition, partial melting reactions, pressure and temperature of anatexis, or magmatic processes that occur during ascent through the crust (e.g. mineral fractional crystallization or crustal assimilation). Together, these diverse factors complicate geological interpretation of the history of peraluminous felsic melt fractions in orogenic settings. To assess the influence of these factors, we performed integrated field investigation, petrology, geochemistry, geochronology and phase equilibrium modelling on a series of leucosomes within migmatite associated with different S‐type granites within the Khondalite belt, North China craton (NCC), which is an archetypal collisional orogen. Three types of leucosome are recognized in the east Khondalite belt: leucogranitic leucosome, K‐feldspar (Kfs)‐rich granitic leucosome and garnet (Grt)‐rich granitic leucosome. Phase equilibrium modelling of partial melting and fractional crystallization processes indicate that the leucogranitic leucosomes were mostly produced through fluid‐present melting, Kfs‐rich granitic leucosomes are produced through muscovite dehydration melting with 3 vol.% garnet fractional crystallization, and Grt‐rich granitic leucosomes are produced through biotite dehydration melting with 20–40 vol.% K‐feldspar fractional crystallization and up to 20 vol.% peritectic garnet entrainment. Mineral fractional crystallization and peritectic mineral entrainment occur in the source during melting, and play equally important roles in partial melting mechanisms in terms of affecting the geochemical compositions of granitic melts. Thus, we suggest that peraluminous felsic magmas preserved in collisional orogens are dominantly produced by fluid‐absent melting in the middle to deep continental crust, although extraction of low‐volume melt fractions from an anatectic source region at shallower depths during fluid‐present melting can also generate small amounts of S‐type granites that subsequently crystallize at high structural levels in the crust.

How cooling surface affect nucleation and impurity migration behavior during layer melt crystallization: A case study of 2′,4′-dichloro-5′-fluoroacetophenone

As a green and efficient purification technology, layer melt crystallization is widely used in chemical separation industry. However, during the melt crystallization process, how surface properties and cooling rate affect the metastable zone width (MSZW) and how MSZW affects the impurity migration in the cooling stage and sweating stage are rare explored. In this paper, 2′,4′-dichloro-5′-fluoroacetophenone is taken as a case study to explore this problem. Firstly, our results indicate that MSZW increases with increasing surface energy of the cooling surface. Importantly, we propose a new model to predict that ΔT/T0/T1 has a linear relationship with ln (R/T0/ΔT), which is validated by MSZW experiments. Secondly, the separation effect of the cooling surface with low surface energy is better than that of the surface with high surface energy. The purity of the crystal layer during sweating is limited by the cooling stage's separation effect. Finally, by employing mass balance, we predict that the impurity distribution coefficient of the crystal layer before and after sweating is linear, and this relationship is unaffected by the cooling surface and cooling rate, which is successfully verified by experiments.

Preparation, luminescence and thermal stability of Tb3+/Eu3+ doped glass ceramics containing KAlSiO4 crystalline phase

The melt-crystallisation process was used to successfully synthesised Tb3+/Eu3+ doped glass ceramics with KAlSiO4 crystalline phase. The optimum heat treatment condition was determined to be 560 °C/90 min by DSC, XRD, SEM and optical transmittance curves, under which the optical transmittance of the glass ceramic in the visible region can reach 80%. Fluorescence spectroscopy was used to determine the energy transfer between Tb3+ and Eu3+, and it was discovered that the energy transfer mechanism was brought on by dipole-dipole interactions. The chromaticity coordinates of the 0.9%Eu3+-0.9%Tb3+ doped sample are (0.3627, 0.3389), it is close to the color of white light. According to variable temperature spectroscopy analysis, emission intensity of Eu3+/Tb3+ co-doped glass ceramics at 458 K can be maintained at 97% and 70% of room temperature at 543 and 614 nm, respectively, demonstrating that the sample has good thermal stability. The results of this study demonstrate the potential of Eu3+/Tb3+ co-doped glass ceramics with KAlSiO4 crystalline phase for use in white light emitting diodes, solid state colour development and other fields.

Thermally stable Dy2O3/Sm2O3 co-doped glass ceramics containing La2Sn2O7 crystal with tunable luminescence

By using the melt crystallization process, Dy2O3/Sm2O3 co-doped glass ceramics (GCs) containing La2Sn2O7(LSO) crystal were successfully prepared. By using X-ray diffraction (XRD), the sample's phase was determined, and scanning electron microscopy (SEM), the sample's morphology was examined. The optimal heat treatment condition of glass ceramics was determined to be 650 °C/1.5 h. Under 362 nm excitation, the energy transfer of Dy3+→Sm3+ was observed in Dy2O3/Sm2O3 co-doped glass ceramic samples from the emission spectrum. Electric dipole-electric dipole interaction is identified as the mechanism of energy transfer from Dy3+ to Sm3+ according to the Dexter formula for energy transfer. The emission spectra of 0.5%Dy2O3-0.4%Sm2O3 co-doped glass ceramic samples in a range from 298 K to 458 K show that the samples have high thermal stability, and the thermal quenching activation energy at 575 nm has been estimated to be 0.265 eV. According to chromaticity coordinates and correlated color temperature, warm white light emission may be achieved by co-doping Dy2O3/Sm2O3 glass ceramics. The findings demonstrate Dy2O3/Sm2O3 co-doped glass ceramics containing La2Sn2O7 crystal have a potential application prospect in warm white light-emitting diodes (w-LEDs).

Functionalized sepiolite intercalated graphene nanostructure reinforced polypropylene composites

The present work developed hybrid polypropylene (PP) ternary composites using PP with different contents of amine-functionalized sepiolite intercalated graphene (f-Sep-Gr) nanofillers through the melt blending method. The amine functionalization on sepiolite intercalated graphene (Sep-Gr) nanostructure was carried out using 3-amino propyl triethoxyl silane. Fourier Transform-Infra Red (FT-IR), X-ray Photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis confirmed the successful functionalization of the amine group into Sep-Gr. Transmission Electron Microscopy (TEM) analysis also confirmed that the amine functionalization didn’t disturb the Sep-Gr morphology. Maleic anhydride graft polypropylene (PP-g-MA) was employed as an interfacial compatibilizer to enhance the dispersion of f-Sep-Gr into the continuous PP phase via a perfect covalent bond interaction. X-ray diffraction (XRD) analysis showed a complete distribution of f-Sep-Gr into the PP/PP-g-MA blend matrix, and the intercalated structure of f-Sep-Gr was not adversely disturbed in the composite. Melt rheological analysis revealed that the composite consisting of the lower content of f-Sep-Gr (0.5 wt%), resulting in a viscous behavior, and a further increase in the content of f-Sep-Gr into the PP/PP-g-MA blend showed viscoelastic solid-like behavior. Differential scanning calorimetry (DSC) analysis revealed that the f-Sep-Gr did not accelerate the melt-crystallization process of PP. In addition, thermogravimetry analysis (TGA) showed that the thermal stability of PP/PP-g-MA/f-Sep-Gr composites improved as a function of f-Sep-Gr content. A small amount of f-Sep-Gr (0.5 wt%) increased Young’s modulus and impact strength of the PP matrix, which is about 123% and 266%, respectively, compared to pure PP. TEM analysis ensured the incorporation of a small fraction of f-Sep-Gr into the blend matrix, forming a three-dimensional network structure in the composite.

Development of Polyhydroxybutyrate-Based Packaging Films and Methods to Their Ultrasonic Welding.

This study developed a technical task associated with the formation of welded joints based on biodegradable polymers and their subsequent physicochemical characterization. The primary objective was to establish the effect of the welding process and modification of natural poly(3-hydroxybutyrate) (PHB) with N,N-dibutylundecenoylamide (DBUA) as a plasticizing agent on the structure and properties of PHB-based biopolymer materials as well as the process and structure of welded joints formation using ultrasonic welding technique. The weldability of biodegradable layers based on PHB and PHB/DBUA mixture was ultrasonically welded and optimized using a standard Branson press-type installation. The effect of the DBUA plasticizer and welding process on the structure of PHB-based biodegradable material was investigated using scanning electron microscopy, X-ray diffraction, FT-IR spectroscopy, differential scanning calorimetry, and thermomechanical analysis. The results confirmed that the DBUA acted as an effective plasticizer of PHB, contributing to lower crystallinity of the PHB/DBUA mixture (63%) in relation to the crystallinity degree of pure PHB film (69%). Ultrasonic welding resulted in an additional increase (approximately 8.5%) in the degree of crystallinity in the PHB/DBUA in relation to the initial PHB/DBUA mixture. The significant shift toward lower temperatures of the crystallization and melting peaks of PHB modified with DBUA were observed using DSC concerning pure PHB. The melt crystallization process of PHB was affected by welding treatment, and a shift toward higher temperature was observed compared with the unwelded PHB/DBUA sample. The butt-welded joints of biodegradable PHB/DBUA materials made using the ultrasonic method tested for tensile strength have damaged the area immediately outside the joining surface.

Glutaric acid purification by coupled solution crystallization and melt crystallization

The mixed dibasic acids (DBA) is a by-product during adipic acid (ADA) production by oxidation of cyclohexanol or cyclohexanone, which contains large amount of glutaric acid (GA) with ADA and succinic acid (SA). In this work, we have explored the feasibility of the coupled solution crystallization and melt crystallization for the purification of GA. To obtain fundamental thermodynamic properties for the process design, the gravimetric method was used to measure the solubility of the three dibasic acids in water from 293.15 K to 345.15 K at atmospheric pressure. The results showed that GA was the most soluble component while all solubility increased with increasing temperature. Therefore, it is reasonable to concentrate GA in the liquid phase by cooling crystallization. Similarly, the ternary solid-liquid melt equilibrium phase diagram was constructed based on the experimental data of the three binary subsystems (GA-ADA, GA-SA, ADA-SA). It was found that the concentrated GA after solvent evaporation could be purified by melt crystallization efficiently. Thus a coupled solution crystallization and melt crystallization process was designed. With the operated operating parameters, the purity of GA could reach 99.06% by secondary melt crystallization. Overall, the coupled solution crystallization and melt crystallization method to separate DBA has proven to be effective.

Nucleating Agents to Enhance Poly(L-lactide) Crystallization and Melting Behavior of Modified Poly(L-lactide)

Melt processing poly(L-lactide) (PLLA) with a nucleating agent has been thought to be one of the most effective route to enhance PLLA s crystallization and heat resistance. In the current work, a newly-developed organic nucleating agent named N, N -bis(2-picolinyl) 1, 4-naphthalenedicarboxylic acid dihydrazide (NCAPH) was synthesized to investigate its effects on PLLA�s crystallization and melting behaviors. It is proved that NCAPH as an organic crystallization nucleating agent could provide large number of crystallization nucleation sites to improve PLLA�s crystallization, as observed from DSC and POM measurements. The result from melt-crystallization processes further showed that the final melting temperature and cooling rate were two important factors for affecting PLLA�s melt-crystallization behaviors in cooling, and the theoretical calculation result of frontier orbital energy indicated there existed probable intermolecular interaction between N-H of NCAPH and C=O of PLLA, which was proposed as nucleation mechanism of NCAPH for promoting PLLA�s crystallization. The melting behaviors of PLLA/NCAPH after non-isothermal crystallization or isothermal crystallization further confirmed the positive effects of NCAPH and NCAPH�s loading for the crystallization of PLLA, meantime, the melting behaviors depended on the heating rate, crystallization temperature, crystallization time, etc.

Non-Isothermal Glass and Melt Crystallization of Poly(3-hydroxybutyrate) Biopolymer: Kinetics and Mechanisms

Biopolymers are the materials familiar for their promising potential of superseding the conventional petrochemical-based polymers. Polyhydroxyalkanotes (PHAs), a sub-class of biopolymers, comprise a group of natural biodegradable polyesters which have found invaluable applications in biomedical science and environmental remediation. This paper reports a detailed kinetic investigation on the non-isothermal glass and melt crystallization of poly(3-hydroxybutyrate) (P3HB) (a key representative of PHAs) by utilizing an advanced kinetic approach to polymer crystallization mechanisms. The kinetic study revealed that both the glass and melt crystallization processes of P3HB pursue single-step nucleation and diffusion phenomena. Moreover, the diffusion activation energies of the aforementioned processes are similar to each other and are in agreement with the universal activation energy value of segmental jumps during diffusion processes in polymers. However, P3HB glass crystallization goes to completion by following a different process mechanism in comparison with its melt crystallization. The P3HB glass crystallization more likely follows interface-controlled two-dimensional (2D) growth of spherulites. The P3HB melt crystallization, on the other hand, pursues diffusion-controlled one-dimensional (1D) growth of spherulites. Thermodynamics points out that the transition state is structurally more oriented in the case of P3HB melt crystallization rather than P3HB glass crystallization. The obtained kinetic and thermodynamic parameters are interpreted in terms of their rational physical meanings and the practical worth of the present study is discussed.

Two new nilotinib polymorphs with solubility advantages prepared by the melt crystallization process

Two new nilotinib polymorphs with solubility advantages prepared by the melt crystallization process

Purification of monoethylene glycol by melt crystallization

Separation of glycols with close boiling points and relatively high viscosity at their melting point is a challenge in the production of high purity products downstream of biorefinery processes. In this work, the efficiency of the layer melt crystallization process with acetone as the assisting solvent was evaluated for a mixture of monoethylene glycol and 1,2-pentanediol. Solid-liquid equilibrium was measured and modelled with the NRTL and modified UNIFAC group-contribution models to evaluate the thermodynamic driving force of crystallization. Layer melt crystallization was conducted to determine the effect of solvent composition on purity, distribution coefficient of impurity, crystal growth rate, and yield at different operating conditions. Addition of the solvent altered the thermodynamics and kinetics of crystallization, thereby altering the purity level of the final product. An effective distribution coefficient of impurity between 0.1 and 0.6 in one-step crystallization was obtained, depending on the solvent composition and the applied operating conditions.

Modeling and Operating Time Optimization of Layer Melt Crystallization and Sweating Processes

Improving the separation efficiency of the layer melt crystallization process is a key but difficult task. Herein, a comprehensive model involving both crystallization and sweating was proposed and used to optimize the operating time of crystallization and sweating processes. The crystallization process was modeled based on the relationship between differential and integral distribution coefficients under a constant layer growth rate. For the sweating process, an empirical sweating equation was employed to govern the sweating model, the parameters of which were determined experimentally using P-xylene as the model substance. The separation efficiency was then optimized by minimizing the operating time at a given product purity and yield. A sensitivity analysis showed that the crystallization and sweating times nonlinearly increase with increasing yield. After the yield exceeds 0.65, an increasing crystallization time is the dominant factor in improving the separation efficiency, while the sweating time and ratio even slightly decrease. The total operating time at low yield is U-shaped with the layer growth rate. The optimal layer growth rate decreases with increasing yield. This model provides guidance for determining the optimal operating parameters of layer melt crystallization and sweating processes.

Combined Effects from Dual Incorporation of ATBC as Plasticizer and Mesoporous MCM-41 as Nucleating Agent on the PLA Isothermal Crystallization in Environmentally-Friendly Ternary Composite Systems.

Different materials, based on an L-rich polylactide (PLA) as matrix, acetyl tri-n-butyl citrate (ATBC) as plasticizer, and mesoporous Mobile Crystalline Material.41 (MCM-41) particles as nucleating agent, were attained by melt extrusion. These materials are constituted by (a) binary blends of PLA and ATBC with different contents of the latest; (b) a dual compound of PLA and a given amount of MCM-41 silica (5 wt.%); and (c) ternary composites that include PLA, ATBC at several compositions and mesoporous MCM-41 at 5 wt.%. Influence of the incorporation of the plasticizer and nucleating particles has been comprehensively analyzed on the different phase transitions: glass transition, cold crystallization, melt crystallization and melting processes. Presence of both additives moves down the temperature at which PLA phase transitions take place, while allowing the PLA crystallization from the melt at 10 °C/min in the composites. This tridimensional ordering is not noticeable in the pristine PLA matrix and, accordingly, PLA crystallization rate is considerably increased under dynamic conditions and also after isothermal crystallization from either the melt or the glassy state. An important synergistic effect of dual action of ATBC and MCM-41 has been, therefore, found.

Prediction of the Layer Growth Rate in Static Melt Crystallization

The crystal layer growth rate is governed by the heat transfer in a layer melt crystallization process and is essential to the separation efficiency. Herein, a numerical model was proposed to predict the solid–liquid (S-L) interface temperature and the growth rate of the crystal layer. The heat transfer equation was taken as the governing equation, combining crystal layer growth kinetics, mass balance, and heat balance in the model which were solved using the finite volume method. The calculation results provided details of temperature distribution in the crystal layer, temperature of the moving S-L interface, and the layer growth rate. The simulated results were validated by experiments using P-xylene as the model substance. Finally, the crystal layer growth rate was found to be very sensitive to the seeding supercooling, especially at the early stage right after seeding. The proper seeding supercooling could be optimized by this model according to both the optimized crystal layer growth rate and productivity.

Role of Heteronucleants in Melt Crystallization of Crystalline Solid Dispersions.

Few publications exist concerning polymorphic control during melt crystallization, particularly when employing heteronucleants. Here, the influence of a polymeric thin film (polyethylene terephthalate, PET) on the crystallization from melt of the polymorphic compound acetaminophen (ACM) in polyethylene glycol (PEG) was investigated. Molten ACM-PEG at different compositions was monitored using in situ Raman spectroscopy for nucleation induction time measurements and phase identification. Furthermore, X-ray diffraction (XRD) served to analyze the preferred orientation (PO) of the pastilles (solidified melt droplets) on PET-coated and uncoated substrates. The results indicate that PET-coated substrates qualitatively accelerate the nucleation of ACM form II (ACM II) in PEG compared to uncoated glass substrates. Additionally, the occurrence of ACM II in PEG was increased by an average of 10% when crystallized on PET-coated substrates compared to uncoated substrates. Overall, these results suggest that ACM can interact through hydrogen bonding with the PET-coated substrate, leading to faster nucleation. This investigation illustrates the effect of PET-coated substrates in the selective crystallization of ACM II in PEG as crystalline solid dispersions (CSDs). Ultimately, the results suggest the implementation of polymeric heteronucleants in melt crystallization processes, specifically, in advanced polymer-based formulation processes for the enhanced polymorphic form control of pharmaceutical compounds in CSDs.