Background: Hot-melt extrusion (HME) is a promising technology for the manufacturing of drug products; however, its application is limited by elevated thermal and shear stresses that may induce degradation of thermolabile active pharmaceutical ingredients. One of the approaches to reducing processing temperatures is the use of polymeric systems with tailored thermal and rheological properties. The aim of the study was to develop an approach for the design of polymeric systems exhibiting a transient plasticization window, enabling a reduction in melt viscosity and improved processability under low-temperature extrusion conditions, followed by the formation of a structurally coherent matrix upon cooling. Methods: The compatibility of the initial polymers was assessed using laser microinterferometry. Based on the obtained data, three- and four-component polymeric compositions were designed and prepared by hot-melt extrusion. The resulting materials were characterized by differential scanning calorimetry, melt rheology analysis, and storage stability assessment. Thermal and rheological data were used to iteratively optimize the polymeric systems. Results: A four-component polymeric system based on PVP K-29/32, PEG 400, PEG 1500, and HPC EF was developed, suitable for processing by hot-melt extrusion at 70 °C. The final system enabled formation of a homogeneous extrudate, exhibited reproducible rheological behavior, and remained stable in the solid-state during storage, with no evidence of cold flow. Conclusions: It was established that, in the design of polymeric systems for hot-melt extrusion, the key factor is not achieving the lowest possible glass transition temperature, but rather the design of a system in which viscosity is transiently reduced under processing conditions and followed by structural stabilization upon cooling. The proposed approach may be applied in the development of polymeric premixes for the preparation of dosage forms by hot-melt extrusion, including those incorporating thermolabile active pharmaceutical ingredients.

Various types of surfactants (Tween 20, Tween 80, Span 20, and Span 80) were used as a stabilizing additive in composites based on petroleum asphaltenes and paraffin - a material that has prospects for use as a phase-transition material in thermal accumulators. The influence of surfactants on the structure and morphology of composites, the rheology of their melts, thermal conductivity, and crystallization ability is shown. An increase in thermal conductivity of 9% has been demonstrated. This correlates with the formation of filler clusters in the presence of surfactants. The presence of surfactants in composites with paraffin has a slight effect on the crystal lattice parameters of paraffin in composites, while the introduction of Tween 20 at a concentration of 1% wt. leads to an increase in the degree of crystallinity of paraffin. In melts of paraffin-asphaltene composites, the network of filler contacts contributes to the presence of a pronounced yield strength. The introduction of a surfactant leads to a decrease in the strength of the contact network and an increase in the fluidity of systems, probably due to the presence of surfactant adsorption layers on the surface of the contacting particles.

The weak point of ionic liquids is their high viscosity, limiting the maximum polymer concentration in the forming solutions. A low-viscous co-solvent can reduce viscosity, but cellulose has none. This study demonstrates that dimethyl sulfoxide (DMSO), being non-solvent for cellulose, can act as a nominal co-solvent to improve its processing into a nanofiltration membrane by phase inversion. A study of the rheology of cellulose solutions in diluted ionic liquids ([EMIM]Ac, [EMIM]Cl, and [BMIM]Ac) containing up to 75% DMSO showed the possibility of decreasing the viscosity by up to 50 times while keeping the same cellulose concentration. Surprisingly, typical cellulose non-solvents (water, methanol, ethanol, and isopropanol) behave similarly, reducing the viscosity at low doses but causing structuring of the cellulose solution and its phase separation at high concentrations. According to laser interferometry, the nature of these non-solvents affects the mass transfer direction relative to the forming membrane and the substance interdiffusion rate, which increases by four-fold when passing from isopropanol to methanol or water. Examination of the nanofiltration characteristics of the obtained membranes showed that the dilution of ionic liquid enhances the rejection without changing the permeability, while the transition to alcohols increases the permeability while maintaining the rejection.

The low thermal conductivity of paraffin and other organic phase change materials limits their use in thermal energy storage devices. The introduction of components with a high thermal conductivity such as graphene into these materials leads to an increase in their thermal conductivity. In this work, we studied the use of inexpensive carbon fillers containing a polycyclic aromatic core, due to them having a structural similarity with graphene, to increase the thermal conductivity of paraffin. As such fillers, technogenic asphaltenes isolated from ethylene tar and their modified derivatives were used. It is shown that the optimal concentration of carbon fillers in the paraffin composite, which contributes to the formation of a structural framework and resistance to sedimentation, is 5 and 30 wt. %, while intermediate concentrations are ineffective, apparently due to the formation of large aggregates, the concentration of which is insufficient to form a strong framework. It has been found that the addition of asphaltenes modified with ammonium persulfate in acetic acid significantly increases the thermal conductivity of paraffin by up to 72%.

Adding carbon nanoparticles into organic phase change materials (PCMs) such as paraffin is a common way to enhance their thermal conductivity and to improve the efficiency of heat storage devices. However, the sedimentation stability of such blends can be low due to aggregation of aromatic carbon nanoparticles in the aliphatic paraffin environment. In this paper, we explore whether this important issue can be resolved by the introduction of a polymer agent such as poly(3-hexylthiophene) (P3HT) into the paraffin-nanoparticle blends: P3HT could ensure the compatibility of aromatic carbon nanoparticles with aliphatic paraffin chains. We employed a combination of experimental and computational approaches to determine the impact of P3HT addition on the properties of organic PCMs composed of paraffin and carbon nanoparticles (asphaltenes). Our findings clearly show an increase in the sedimentation stability of paraffin-asphaltene blends, when P3HT is added, through a decrease in average size of asphaltene aggregates as well as in an increase of the blends' viscosity. We also witness the appearance of the yield strength and gel-like behavior of the mixtures. At the same time, the presence of P3HT in the blends has almost no effect on their thermophysical properties. This implies that all properties of the blends, which are critical for heat storage applications, are well preserved. Thus, we demonstrated that adding polyalkylthiophenes to paraffin-asphaltene mixtures led to significant improvement in the performance characteristics of these systems. Therefore, the polymer additives can serve as promising compatibilizers for organic PCMs composed of paraffins and asphaltenes and other types of carbon nanoparticles.

The work is devoted to evaluation of the thermal conductivity of composites based on asphaltenes and paraffin as a phase change material. Asphaltenes with different structural characteristics, obtained by chemical modification and fractionation were used to improve the heat conductivity of paraffin. Modification of asphaltenes with sulfuric acid and oleum made it possible to obtain samples with increased content of condensed structure fragments and minimum content of aliphatic ones. The form of modified asphaltenes neutralized with diethanolamine was also investigated. Asphaltene molecules with increased aliphatic content were isolated by fractionation with toluene / acetone mixtures. Structural, thermophysical and rheological properties of composites based on paraffin and these types of asphaltenes are analyzed. It is shown that the introduction of asphaltenes into the paraffin matrix does not violate its ability to crystallize, but leads to a decrease in the degree of crystallinity and an increase in the crystallization temperature. The increased content of the condensed structures in modified asphaltenes leads to strong agglomeration, and as a result, to a decrease in the thermal conductivity of the composite material at room temperature. The introduction of asphaltenes with high aliphatic fragments content ensures their more uniform distribution in the paraffin matrix, which contributes to an increase in the thermal conductivity of the system.

Polymer hot-melt adhesives are obtained on the basis of poly(ethylene-vinyl acetate), polyethylene wax, and aromatic (C9) hydrocarbon resins differing in the degree of hydrogenation of aromatic groups (from 0 to 37%). The content of poly(ethylene-vinyl acetate) is varied from 30 to 80%, and the concentration of other components of the adhesive is within 10–35%. The rheology of adhesive components and blend compositions is studied in detail, and the adhesion characteristics of the adhesives are determined. It is found that the use of a nonhydrogenated resin leads to high adhesion properties of the adhesive but imparts viscoplasticity to it. The use of a hydrogenated resin provides better rheological properties of the adhesive, but a higher content of poly(ethylene-vinyl acetate) is required to achieve good adhesion characteristics.

Materials-science aspects of the development of color road pavement (color asphalt concretes) and marking are considered. Kinds of binders used as a base for color asphalt concretes are characterized; these include dark petroleum bitumens, colorless polymer binders, and biobinders. The main requirements to colorless binders are formulated. The relationship between the composition and physicochemical, mechanical, strength, rheological, and service properties of the materials in question are demonstrated. The main types of road marking materials and their formulations and components are considered. The important trends in the development of road marking materials are a decrease in the content of organic solvents in the formulation and their replacement by biodegradable solvents produced from renewable resources. Much attention is paid to improvement of the visual contrast of the road marking under different weather conditions. High-tech smart and dynamic marking systems are being developed for this purpose.

Curing of epoxy resins with aromatic amines, which provides an excellent combination of physical and mechanical properties, requires high temperatures. In this research, the amidoamine adduct of tall oil with triethylenetetramine have been used for acceleration of the reaction of the aromatic amine (diaminodiphenyl sulfone, DDS) with the diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The kinetics of the curing reaction of DGEBA with a mixture of two hardeners was investigated by the non-isothermal DSC method. It was shown that the activation energy of curing decreased from ~ 68 to ~ 59 kJ/mole at amidoamine introduction. Nevertheless, there were no new bands in the IR-spectra of the cured epoxy resins. The acceleration of the curing reaction of the aromatic amine was apparently due to the autocatalytic action of the hydroxyl groups formed by the reaction of the epoxy resin with the amidoamine. Besides acceleration of curing, use of the hardener mixture significantly increased the rubbery-plateau modulus, while not influencing on the value of the elasticity modulus of the cured resin in the glassy state. A disadvantage of using amidoamine for accelerating the curing was lowering of the glass transition temperature of the cured polymer.

Asphaltenes are harmful components of heavy crude oils and require rational utilization after oil refining or deasphalting. Asphaltenes are macromolecules containing various functional groups that self-assemble to nanoscale aggregates and can be used as nanofillers for polymers. In this research, mixtures of asphaltenes with the diglycidyl ether of bisphenol A were considered. The solubility of asphaltenes in this epoxy resin, the rheological properties of the mixtures, and the effect of asphaltenes on the curing with 4,4 '-diaminodiphenyl sulfone were studied. In addition, the glass transition temperature, strength, and adhesion characteristics of the asphaltene-filled cured composites were evaluated. The dual role of asphaltenes in polymer modification was demonstrated: the asphaltenes simultaneously plasticize and reinforce the polymer matrix, and the transition from predominant plasticization to strengthening occurs with an asphaltene content at 20 wt%. The dual reinforcement/plasticization effect occurs because epoxy composites contain both nanosized and microsized particles of asphaltenes due to the partial dissolution of asphaltenes in the epoxy resin and the decrease in their solubility during high-temperature curing.

The effect of the nature of a coagulant on the nanofiltration characteristics of the cellulose membranes obtained from solutions in 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) or a mixture of this ionic liquid with dimethylsulfoxide (DMSO) is studied in this work. Precipitation in water leads to the formation of the densest cellulose membrane characterized by the low permeability of dimethylformamide (PDMF = 0.25 kg m−2 h−1 atm−1) and high rejection coefficients of the model substances, Orange II (350 g/mol) and Remazol Brilliant Blue R (626 g/mol), of 65 and 82%, respectively. To reduce the rate of precipitation of cellulose for the purpose of decreasing the density of the membranes, various compounds that partially mimic the medium of the solvent are introduced to water to obtain their 30% solutions: acetic acid to increase the concentration of acetate anions, N-methylmorpholine N-oxide to increase the concentration of ammonium fragments, and DMSO. In all the cases, the modification of the coagulant leads to a 2–2.5-fold increase in the permeability of the membranes without sacrificing the high values of the rejection coefficients. A cellulose membrane obtained by precipitation in a 30% aqueous solution of acetic acid demonstrates the best nanofiltration characteristics, namely, PDMF = 0.67 kg m−2 h−1 atm−1, ROrangeII = 66%, and RRemazol = 78%.

An approach for fabrication of microfiltration membranes by solvent extraction of one of the immiscible components from a polymer blend was developed. Poly(4-methyl-1-pentene) (PMP) was the membrane material, and poly(isobutylene) (PIB) was the extractable component. The PIB content varied in the wide range 0-45 wt%, and all blends could be melted and processed at a temperature of 240 degrees C. A rheological study demonstrated a pronounced non-Newtonian behavior of PMP/PIB blends and their very low viscosity due to interlayer slip. With a PMP content of 55 and 60 wt%, it was possible to fabricate microfiltration membranes with a water permeability of 31 and 3.7 m(3) m(-2) h(-1) bar(-1), respectively. The microfiltration membranes based on both compositions demonstrated good rejection performance at the level of 93%-98% for submicron particles of phthalocyanine dye with a size of 240 nm. These results indicate that the PMP/PIB system can be utilized for fabrication of filtration membranes by means of 3D printing followed by solvent extraction. (c) 2019 Society of Chemical Industry

A series of microfiltration membranes were fabricated by the extraction of polyisobutylene (PIB) from its immiscible blends with polymethylpentene (PMP). Three PIB with different molecular weight of 7.5 × 104 (Oppanol B15), 34 × 104 (Oppanol B50) and 110 × 104 (Oppanol B100) g/mol, respectively, were used to evaluate the effect of molecular weight on the porous structure and transport properties of resulting PMP-based membranes. To mimic the conditions of 3D printing, the flat-sheet membranes were fabricated by means of melting of mixtures of various PMP and PIB concentrations through the hot rolls at 240 ∘ C followed by a quick cooling. The rheology study of individual components and blends at 240 ∘ C revealed that PIB B50 possessed the most close flow curve to the pure PMP, and their blends demonstrated the lowest viscosity comparing to the compositions made of PIB with other molecular weights (B15 or B100). SEM images of the cross-section PMP membranes after PIB extraction (PMP/PIB = 55/45) showed that the use of PIB B50 allowed obtaining the sponge-like porous structure, whereas the slit-shaped pores were found in the case of PIB B15 and PIB B100. Additionally, PMP/B50 blends demonstrated the optimum combinations of mechanical properties (str = 9.1 MPa, E = 0.20 GPa), adhesion to steel (adh = 0.8 kPa) and retention performance (R240 nm = 99%, R38 nm = 39%). The resulting membranes were non- or low-permeable for water if the concentration of PIB B50 in the initial blends was 40 wt.% or lower. The optimal filtration performance was observed in the case of PMP/B50 blends with a ratio of 55/45 (Pwater = 1.9 kg/m2hbar, R240 nm = 99%, R38 nm = 39%) and 50/50 (Pwater = 1100 kg/m2hbar, R240 nm = 91%, R38 nm = 36%).

Microfiltration membranes have been obtained from polymethylpentene by phase separation of its dioctyl sebacate solutions under cooling. The dissolution of the polymer was carried out at its melting point followed by formation of membrane precursors in the form of films from the resulting solution, which were then cooled and washed with acetone to remove the ester and pore formation. Using laser interferometry, it is shown that the phase diagram of the polymethylpentene–dioctyl sebacate system corresponds to amorphous separation with the UCST. The rheology of solutions is studied by rotational rheometry, and it found that the logarithm of viscosity decreases linearly with increasing concentration of dioctyl sebacate. According to calorimetry, dioctyl sebacate plasticizes polymethylpentene, reducing its crystallinity. Treatment of the resulting films with acetone leads to the complete extraction of dioctyl sebacate, and, at its concentration of 25–45 wt %, a through porous structure is formed. This procedure makes it possible to obtain fairly strong membranes with a water permeability of 16.4 kg/(m2 h atm) and a retention coefficient of submicron particles with a diameter of 240 nm equal to 80%.

Dispersions based on sodium hyaluronate and hydroxyapatite, which is synthesized both by the classical method in an aqueous medium to obtain submicron particles and in a bioactive hyaluronan medium with the formation of nanosized particles, are obtained. The synthesized hydroxyapatite nanoparticles have a complex structure based on a monodentate complex hyaluronan–Ca 2+ which remains in the dispersion both when adding a hyaluronan solution and when diluted with water. Physicochemical methods show that there is a significant difference between the energy characteristics of the surfaces of biocomposites obtained from dispersions. The rheology of dispersions of hydroxyapatite micro- and nanoparticles is investigated, the effect of dispersed phase concentration on it is revealed, and the viscoplastic behavior of dispersions of microparticles is demonstrated. This behavior disappears upon addition of the hyaluronan solution, which, however, leads to the loss of stability by the system. The introduction of hydroxyapatite nanoparticle additives into hyaluronan solutions has a weak effect on the rheology; no flocculation of nanoparticles occurs. The resulting composites consisting of hydroxyapatite and sodium hyaluronate can be considered a basis of a drug for the rehabilitation treatment of periodontitis.

Phase behavior, rheology and adhesive properties of polyisobutylene-based blends containing up to 60 wt% of polyethylene wax were studied. Polyisobutylene and wax partially dissolve in each other at high temperatures, which strongly reduce the viscosity of the blends and facilitate their mixing. When cooled, the wax loses its solubility in the polymer matrix and crystallizes to form reinforcing particles. These particles increase the viscoelasticity of the blends, resulting in improved durability (up to 66-fold) and strength (up to 1.4-fold) of adhesive bonds. At the same time, the growth of viscoelasticity does not lead to a loss of tackiness of the blends, as the application of external force to form an adhesive bond destroys the percolation structure of wax particles. Because of the low specific surface area of wax particles, they increase the durability of adhesive joints worse than silica (in 380-fold) or organoclay particles (in 3300-fold). However, the use of polyethylene wax allows reducing melt viscosity by 4-5 decimal orders of magnitude in the case of highly filled adhesives.

The use of heavy crude oil asphaltenes and resins (termed asphaltenes) as the components of hot-melt adhesives based on the styrene-isoprene triblock copolymer was considered. The rheological, thermophysical, strength, and adhesive characteristics of the mixtures containing from 10 to 40 wt% of asphaltenes were studied. The addition of 10 to 20 wt% of asphaltenes enhanced the strength and adhesive properties of the mixtures and only slightly changed their rheology. The higher concentrations of asphaltenes reduced the viscosity of the mixtures but did not lead to improved characteristics of the adhesives. The ambiguous effect of asphaltenes is probably due to their uneven distribution between the microphases of the block copolymer as well as their ability to act both plasticizers and reinforcing particles depending on temperature. A comparison of asphaltenes and conventional tackifiers based on hydrocarbon resins revealed their comparable effect on the properties of the block copolymer.