Solubility Parameter Difference Research Articles

Influence of compatibilization methods on the compatibility between asphalt and DCLR components with molecular dynamics (MD) method

This study aims to investigate the effect of compatibilization methods on the compatibility between asphalt and direct coal liquefaction residue (DCLR) components to identify the key components in DCLR and asphalt that affect their compatibility. In this article, three types of compatibilizers, including benzyl alcohol (BA), dioctyl phthalate (DOP), and BA/DOP, were selected and acted on asphalt's components and DCLR's components, respectively. The molecular models of asphalt components, asphalt components with compatibilizers, DCLR components, and DCLR components with compatibilizers were established. The compatibility between DCLR and asphalt's four components, as well as between asphalt and DCLR's three components, were evaluated by solubility parameter difference (SPD) and interaction energy (IE). The compatibility between DCLR and asphalt was analyzed by Segregation test and Scanning Electron Microscope. Results indicate that the SPD and IE values between DCLR and asphalt components declined after adding compatibilizers, which implies that the repulsion decreased and the attraction increased between asphalt components and DCLR and the compatibility between asphalt components and DCLR improved. The IE values between DCLR components and asphalt increased after adding compatibilizers, which indicates that the compatibility was reduced between DCLR components and asphalt. The SPD values between DCLR components and asphalt increased after adding the BA/DOP. The SPD values between pre-asphaltene and asphalt decreased after adding the BA and DOP. The SPD value between asphaltene in DCLR and asphalt increased after adding the BA and decreased after adding the DOP. Moreover, the storage stability and homogeneity of DCLR-modified asphalt improved after adding compatibilizers, indicating that the compatibilizers enhanced compatibility between DCLR and asphalt. Finally, comparing the results of the tests, it could be found that compatibilizers preferentially acted on the asphalt components and mainly affected the aromatics in asphalt, thereby improving the compatibility between asphalt and DCLR. The effect of BA/DOP on improving the compatibility between asphalt and DCLR was better than that of BA and DOP.

Divinyl polysiloxane modified polyacrylate for promoting the directional migration of disperse dyes in digital jet dyeing of polyester fabric without washing

Future developments in the printing and dyeing industry will involve greenisation and personalisation. Less/no water digital technology has drawn much attention over traditional printing and dyeing for reducing carbon and emissions. Based on the solubility parameter difference between disperse dyes and monomers, divinyl polysiloxane modified polyacrylate (PSMA) with the directional migration effect for disperse dyes was prepared herein via mini-emulsion polymerisation. PSMA was used as wash-free polymer additive in the digital jet dyeing of polyester fabrics with disperse dyes, which yielded wash-free dyed fabrics with high color yield and color fastness. The results showed that PSMA achieved the optimum overall performance at a molar ratio of octamethylcyclotetrasiloxane to 1,3-divinyltetramethyldisiloxane 44:1 and divinyl polysiloxane dosage of 4 wt%. PSMA had the best tensile properties, good flexibility, certain hydrophobicity and high directional migration of disperse dyes. When the PSMA dosage was 9 wt% in the wash-free ink, the front and back color yield of the wash-free dyed fabric were 18.23 and 13.56, respectively. Compared with the fabric dyed with pure liquid disperse red, the front color yield of the wash-free dyed fabric increased by about 35.2 % and the back color yield had a little change. Its color fastness to dry/wet rubbing were improved from grade 3 to 4 and from grade 2–3 to 3, respectively. The handle of the wash-free dyed fabric basically maintained the level of original fabric.

Tailoring compatibility and mechanical properties of cold-mixed epoxy asphalt via external epoxy group content manipulation

The compatibility of cold-mixed epoxy asphalt (CEA) significantly influences its mechanical properties, primarily mediated by the epoxy group content within CEA. However, the feasibility and mechanisms for regulating the external epoxy group content to achieve optimal performance have yet to be explored thoroughly. Herein, soybean oil, epoxidized soybean oil, and epoxy-terminated hyperbranched epoxy resin (EHER) were used to construct CEA with different external epoxy group contents, and their effects and mechanisms on the compatibility and mechanical properties of CEA were investigated based on experiments and molecular dynamics simulation. Our findings suggest that maintaining an external epoxy group content between 8.4%∼11.4% in the CEA blend and below 12.17% in the cured CEA is crucial. These criteria can be met by adding no more than 5 wt% EHER. CEA with 3 wt% EHER exhibited the most balanced compatibility and mechanical properties, characterized by a pot life of 91 min, a tensile strength of 5.02 MPa, an elongation at break of 61.3%, and a tensile toughness of 1.58 MJ/m3. The presence of external epoxy groups increased the cohesive energy density and the solubility parameter difference between epoxy resin and asphalt prior to curing, forming a "sea-island" structure with varying particle sizes, primarily comprising small-sized particles. This structure was preserved post-curing, establishing a stable system with minor energy alterations. Simultaneously, EHER enhanced the molecular rigidity and uniformity of CEA, thereby improving its mechanical properties. It is recommended to relate epoxy group content in CEA blends with indicators of compatibility and mechanical properties, enabling better prediction.

Experimental studies and molecular dynamics simulation of the compatibility between thermoplastic polyurethane elastomer (TPU) and asphalt

Compatibility between polymer and asphalt is an important issue to be considered when the polymer is added to base asphalt as a modifier. It determines the stability of the modified asphalt system. The purpose of this paper is to investigate the effect of shearing temperature and the content of thermoplastic polyurethane elastomer (TPU) on the compatibility between TPU and asphalt by means of experiments and molecular dynamics simulations. Firstly, the molecular models of base asphalt, TPU chain and TPU/asphalt blends were constructed by using Materials Studio 8.0. Based on the rational construction of the model, the effect of shearing temperature on the storage stability of TPU modified asphalt was evaluated by the calculation of solubility parameter (δ) and mean square displacement (MSD). In addition, the effect of different TPU admixtures on the compatibility of TPU with asphalt was characterized by interaction energy and radial distribution function (RDF). The results of molecular dynamics calculation were compared with the results of fluorescence microscopy test (FM) and segregation test. It showed that the minimum difference in solubility parameters between TPU and asphalt occurs when the shearing temperature was 170 °C, at which the diffusion movement of TPU in asphalt was the most active. The interaction energy between TPU and asphalt reached the peak when the content of TPU in asphalt was 17 wt%. Furthermore, the RDF results also indicated that the optimum dispersion effect of TPU in asphalt is achieved at this TPU content. The molecular dynamics simulation results are in agreement with the experimental results.

Novel method for the prediction of distribution and elution characteristic of several drugs in cellulose diacetate-water system: Interaction between mixed solvent and cellulose diacetate

Drug-loaded cellulose diacetate (CDA) membranes were prepared by dissolving cellulose diacetate in a mixed solvent of acetone and ethanol, adding the drug to it, pouring it on a glass plate and evaporating the solvent. In this study, it was prepared CDA membranes varying composition of the mixed solvent (the mass ratio of acetone (ACE) to ethanol (EtOH)) and investigated their microstructure and performance.The release properties of drugs in drug-loaded CDA membranes were examined in correlation with the composition of the mixed solvent and a method to be able to predict the release properties of drugs was proposed. Penicillin G potassium, streptomycin sulfate and ampicillin were used as drugs. The microstructure of the membranes was determined using SEM analysis and the release properties of drugs were measured using spectrofluorophotometer. It was shown that the composition of the mixed solvent can have a significant effect on the overall performance of CDA membrane. The intrinsic viscosity measurements and solubility parameter analysis proved that the intrinsic viscosity of CDA in polymer solutions with mixed solvents and the solubility parameter difference (Δδ) between mixed solvents and CDA were relative with the release properties of drugs. The release rates of drugs from the membrane related to △δ directly and the intrinsic viscosity inversely. Therefore, the release rates of drugs from CDA membrane can be controlled by changing the composition of the solvent used for the preparation of the polymer membrane.

Investigation of the effects of chemical modification and oxidative aging on the properties and compatibility of rubber asphalt based on thermodynamic principles

This study is based on the principles of thermodynamics and utilizes the Hansen solubility parameter theory and molecular dynamics simulation techniques. By introducing solubility parameters and interaction parameters, modified molecular models for rubber and aged asphalt are constructed. The study systematically investigates the mechanisms underlying the effects of polyphenolic chemical modification and oxidative aging on the performance and compatibility changes of rubber asphalt. The results show that the solubility parameter (δT) of the asphalt system decreases gradually with increasing temperature. At a temperature of 160 °C, the solubility parameter difference (ΔδT) between the asphalt and rubber power (RP) is minimized, indicating the highest degree of compatibility between the two materials. After chemical modification, the solubility parameter of the RP increases, the difference in solubility parameter between the RP and asphalt decreases, and the chemical modification improves the compatibility of the two phases. Oxidative aging causes a shift in the composition ratio of asphalt towards asphaltene, leading to an increase in the solubility parameter of asphalt and a larger difference in solubility parameter between the system. As a result, the compatibility of modified asphalt decreases.

Conceptual stabilizer selection for nanomilling based on dispersibility parameters

The choice of stabilizers to prevent particle agglomeration during nanomilling is an elaborate process which is often based on empirical rules and experience. Usually, extensive screening studies are required to find an appropriate stabilizing additive. The present study shows how the selection of polymeric stabilizers can be narrowed down to a couple of additives based on Hansen solubility parameters. The stabilizing capability was found to be a function of the difference between solubility parameters of additive and particulate species. Solubility parameters of different additives and two particle species were determined by inverse gas chromatography and the stabilization performance was evaluated by nanomilling experiments conducted with a stirred media mill. It is shown that a certain difference of solubility parameters between particle and additive is necessary in order to provide colloidal stability of small particles after milling. On the one hand, the additive needs a certain affinity to the particle surface, while on the other hand it also has to be compatible with the solvent. Based on experimental data, a solubility parameter difference in the range of 7.5–10 MPa0.5 was identified as a good measure for a proper stabilizer selection. The approach was proved for two organic particle species and represents a promising tool for a more efficient formulation development of drug nanosuspensions.

Phase-Separated Structure of NBR/PVC Blends with Different Acrylonitrile Contents Investigated Using STEM-EDS Mapping Analysis.

We investigated the phase-separated structure of nitrile butadiene rubber (NBR)/polyvinyl chloride (PVC) blends with different acrylonitrile (AN) contents in the NBR, using dynamic mechanical analysis measurements and scanning-transmission-electron-microscopy (STEM)-energy-dispersive-X-ray-spectroscopy (EDS) elemental analysis. Two separate sharp tan δ peaks were observed in the blend at the lower AN content of 18.0%, whereas a broad peak was observed in the blends with the higher AN contents of 29.0 and 33.5%, due to the increase in miscibility, as expected from the decrease in the solubility parameter difference with the increasing AN content. The STEM-EDS elemental analysis for the concentration distribution showed that the NBR was mixed in the large PVC domains with a diameter of several micrometers, and the excluded PVC existed around the interface of the domain-matrix phases in the blend with the lower AN content, whereas small domains with a diameter of several tens of nanometers were dispersed in the blend with the higher AN content. The concentration difference in PVC between the PVC domain and the NBR matrix became smaller with increasing miscibility as the AN content increased although the blends contained the same PVC content of 40 wt%.

Enhancing the compatibility of cold-mixed epoxy asphalt binder via graphene oxide grafted plant oil-based materials

Cold-mixed epoxy asphalt (CEA) has attracted extensive attention in overloaded and steel bridge pavement and maintenance engineering because of its room temperature construction and low energy consumption. However, the compatibility of epoxy resin and asphalt in CEA is still a challenge, limiting its application to some extent. This study aims to enhance the compatibility of CEA with low amounts of plant oil-based compatibilizers and suggest appropriate methods for assessing the compatibility of CEA. GO-grafted epoxidized soybean oil (GOESO) and GO-grafted soybean oil (GOSO) were synthesized and used to modify CEA. The GO and ESO (or SO) solutions were prepared at concentrations of 0.5 mg/mL and 5 mg/mL, respectively. The pH of the solution was adjusted to 5∼6 before heating. The results showed that 0.2 wt% of GO-modified oil-based compatibilizers had similar effects as 30 wt% of oil-based compatibilizers and did not significantly alter the crystal and chemical structures of the CEAs. GOESO is the preferred recommended GO-modified compatibilizer because of the enhanced compatibilizing ability of the epoxy groups in ESO. The compatibilization mechanism involved the effects of the oils on the chemical structures, curing reaction rate, and microstructures of CEAs. The proportion of asphalt particles larger than 20 μm and the reaction rate had strong correlations with the mechanical properties of the cured CEAs. Molecular dynamics simulations revealed that GOSO reduced the solubility parameter (δ) and Flory-Huggins parameter (χ) difference between components A and B by 39.4% and 65.8%, respectively, while GOESO increased the δ and χ difference between components A and B by 10.4% and 15.8%, respectively.

6FDA-DABA polyimide, polyphenylene, and polyimide-polyphenylene multiblock synthesis, characterization, and membrane gas separation performance and modeled transport

A 6FDA-DABA (6FD) polyimide, polyphenylene (PP), and multiblock copolymer (6FD-PP) materials were synthesized using sequential polycondensation and Diels-Alder reactions. PP and 6FD solubility parameters were 19.4 (MPa)1/2 and 22.4 (MPa)1/2, as predicted using Group Contribution Theory. Due to their solubility parameter differences, PP and 6FD solutions in tetrahydrofuran became immiscible when mixed at all concentrations. However, 6FD-PP multiblock copolymer solutions were clear, and their solution-cast films were robust and creasable. Homopolymer and block copolymers estimated fractional free volume (FFV) ranged from 0.174 (6FD) to 0.196 (PP). Their densities and FFV largely obeyed the rule of mixtures, suggesting a "blend-like" morphology. The glass transition temperature (Tg) of 6FD and PP were 285 °C and 400 °C, which became two distinct Tgs at 340 °C and 420 °C for 6FD-PP-[14k:13k]. Larger PP block lengths appeared to suppress the first-order polyimide transition entirely. SAXS and AFM morphological analysis revealed two distinct domains with an average separation distance ranging from 9.0 to 47.7 nm, dependent on PP block length. Membrane gas separation performance was compared to Robeson's upper bound. 6FD-PP multiblock copolymer gas transport properties were found to be highly dependent upon copolymer composition and FFV. Increasing PP content within a copolymer significantly improved gas permeability at the expense of He/CH4 and CO2/CH4 selectivity. Membrane CO2 permeability ranged from 4.36 Barrers using 6FD to 155 Barrers with PP. Their CO2/CH4 selectivity varied between 80.6 (6FD) to 12.7 (PP). 6FD-PP-[14k:13k] membrane's O2 permeability was between these polymers. The membrane had a 30% improvement in its ideal O2/N2 selectivity. The N2/CH4 selectivity ranged from 3 to 1.70, suggesting that 6FD-PP multiblock systems could be efficiently tailored from N2 to CH4 selectivity. Five gas permeability models (rule-of-mixture, Maxwell, EBM, laminate, and blend) were used to study 6FD-PP block copolymer transport behavior. Among them, a blend model had the most reasonable gas permeability prediction. 6FD-PP multiblock membranes improved several ideal gas pairs leading to more permeable and selective materials. The synthetic approach using block copolymerization creates an opportunity for gas separation improvement and tuneability of specific gas pairs.

Nano-microscopic analysis on the interaction of new and old asphalt mortar in recycled asphalt mixture

Asphalt and fillers form asphalt mortar, which plays the role of bonding and filling in the asphalt mixture, and has a significant impact on the performance of the asphalt mixture. However, it is very necessary to fully study the interaction between old and new asphalt mortar in recycled asphalt mixture. In this study, molecular dynamics simulation software (Material Studio 8.0) was used to study the interface action of old and new asphalt mortar and the mechanical properties of the mixed old and new asphalt mortar. Quantification and characterization of solubility parameters, interaction energy, and mechanical properties from a microscopic perspective. In order to better demonstrate the simulation results, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to conduct microstructural tests to clarify the interaction of old and new asphalt mortar in recycled asphalt mixtures. The results show that at 190 °C, the solubility parameter difference of the old and new asphalt mortar molecular models and the interaction energy are in the best mixing state. At this temperature, the SEM surface morphology characterization is relatively good; the quantitative characterization of the functional groups also shows that the two have a good relationship. the miscible state. The mechanical properties of new and old asphalt mortars are described at the nano and micro scales, and the mechanical properties recover after miscibility. The above results show that it is a comprehensive and reliable method to conduct multi-scale research on the interaction of old and new asphalt mortar in recycled mixtures, and provide new ideas for the research of polymer materials.

Selective solvent vapor induced self-assembly of silicon-containing bottlebrush block copolymer thin films to generate mesoporous silicon oxide patterns

Bottlebrush block copolymers (BBCPs) are intriguing architectures that can produce various anisotropic nanostructures dictated by the composition, length of the backbone and the lengths of side-chains. Here, we develop a facial approach toward ordered inorganic silicon oxide patterns and particles on substrates by solvent vapor induced thin film self-assembly of anisotropic bottlebrush block copolymers (BBCP) containing polydimethylsiloxane (PDMS) and polystyrene (PS) side chains. The in-plane cylindrical or stripes-like, spherical, and ordered porous morphologies as well as Janus particles-like morphology were fabricated on the substrate through solvent vapor annealing (SVA). The Janus particle-like morphology consisting of PS heads inserted in PDMS heads were directed to produce meso-to macroporous silicon oxide bowls after oxygen plasma etching. The effects of the solvent vapor on the molecular geometry and morphology of the BBCPs were described, and the influence of the backbone length on the self-assembly behavior of the thin film were discussed. This work demonstrates that silicon-containing BBCPs with a native etch contrast and a large difference in solubility parameters are potential candidates to generate ordered silicon oxide templates of different geometries with periodicity 80–150 nm providing access to length scales larger than linear block copolymers.

Kinetic and Thermodynamic Studies in Cellulose Acetate-Polybutylene Succinate(CA-PBS)/Single Solvent/Water System for Desalination Membrane

The most important part of the membrane synthesis process so that it has the desired pores is the solidification process of the membrane, the process begins with a change from one liquid phase into two liquid phases (liquid-liquid demixing). At a certain period during demixing, the polymer-rich phase solidifies; thus, a dense membrane matrix is formed. Parameters that determine the mechanism of membrane formation are based on thermodynamics including phase separation of Solvent-Polymer-Non-solvent which is explained through a phase diagram (Flory-Huggins Theory). This study aims to determine the initial prediction of the formation of CA-PBS membranes with various solvents used and variations of non-solvents in the best system, which is proven by its characteristics and performance when applied to desalination membranes which include ternary diagrams using cloud point data, solubility parameters with Hansesn solubility, the solvent-non-solvent diffusivity using the Tyn Calus Equation approach and the morphological proofing of the membrane through SEM photos, and the performance of the resulting membrane through salt rejection and permeate flux. The results of the difference in solubility parameters are can be predicted that using DMF solvent on the CA-PBS membrane can reduce the pore size and eliminate voids and macrovoids in the membrane morphology.

Elucidating the effect of the physicochemical properties of organosolv lignins on its solubility and reductive catalytic depolymerization

Unsatisfactory solubility and recalcitrant condensed structures of isolated lignins (technical lignins) severely limit their processability into renewable materials, fuels, and chemicals. Therefore, a comprehensive understanding of the structural and physicochemical properties of isolated lignins is of great value in explaining their performance in the solubilization and further depolymerization to high-value applications. In this work, we investigated the solubilization and depolymerization performance of organosolv lignins from three different sources (beech (L01), birch (L02), and wheat straw (L03)). We applied sequential solvent fractionation as a tool to subdivide parent lignins into four more homogeneous subfractions (SF1, SF2, SF3, and IF), with a gradual increase in molecular weight and interunit linkages and a decrease in phenolic –OH group from SF1 to IF. The solubility tests of the parent lignins and their subfractions at ambient conditions were carried out in six organic solvents (n-hexane, diisopropyl ether, ethyl acetate, ethanol, methanol, and acetone) with large differences in Hansen solubility parameters. Among the solvents studied, the solvents with δp > 8 MPa1/2 demonstrated a high solubilization yield of organosolv parent lignins and their subfractions. The solubilization behavior of parent lignins and subfractions was further described based on their inherent structural properties, such as molecular weight and functional group content (phenolic –OH and –COOH). The structure–reactivity characteristics of parent organosolv lignin and their subfractions were also investigated under different conditions in the presence of catalyst-containing transition (NiHTC-500) and noble (Pd/C) metals as active centers. Strong structural correlations between parent lignin/subfractions and depolymerized lignin oils were derived using GC-FID/MS, GPC, 1H–13C HSQC NMR, and 31P NMR.

Evaluation of the affinity of asphaltene molecular models A1 and A2 by the water/oil interfaces based on a novel concept of solubility parameter profiles obtained from MD simulations

Crude oils are formed of asphaltenes that are species soluble in certain solvents such as toluene. The distribution of asphaltene models and their mixtures in water/n–heptane and water/toluene systems were explored with MD simulations. A1 and A2 asphaltene models were used for the exploration of the affinity of these compounds by the water/oil interfaces. For this, a novel concept called solubility parameter profiles was used to characterize the polarity of the regions present in water/n–heptane and water/toluene systems. Molecules of asphaltene models, n–heptane, and toluene were described with the GROMOS53A6 force field and CHELPG atomic charges, and water molecules with the SPC model. The prediction of the affinity of A1 and A2 asphaltene models at interfaces was determined using the total solubility parameter differences calculated between these species and solvent molecules. Calculated solubility parameters show a good correlation with experimental values. Total solubility parameter differences equal to Δδtotal = 3.76 MPa0.5 and Δδtotal = 0.36 MPa0.5 at the water/n–heptane interface suggest that asphaltene models have a good affinity by the water/n–heptane interface in comparison with the water/toluene interface whose values were Δδtotal = 5.82 MPa0.5 and Δδtotal = 9.94 MPa0.5 for A1 and A2 asphaltene models, respectively. It was demonstrated that the affinity of asphaltenes by a specific region of the immiscible system is controlled by the electrostatic and dispersive contributions associated with the solubility parameter profiles.

Study on Mechanical Properties of Two-Component Polyurethane Based on Multi-Scale Molecular Simulation.

Mechanical properties determine the use of two-component polyurethane materials. The compatibility of two components in the polyether polyol-MDI molecular system greatly influences the formation of mechanical properties in polyurethane materials. In this paper, we studied and evaluated the compatibility and mechanical properties of two-component polyurethane at multiple scales by combining molecular dynamics simulation with macroscopic experiments, which is an important guideline for synthesizing and preparing two-component polyurethanes. We evaluated the stability of the two-component polyurethane system by calculating the solubility parameter, binding energy, and diffusion coefficient at four temperatures with three isocyanate contents. The Perl scripting language obtained the mechanical properties of the MDI-polyether polyol system. The MD calculation results show that the solubility parameter of two-component polyurethane negatively correlated with temperature, and the intermolecular binding energy and MDI diffusion coefficient positively correlated with temperature. When the mass ratio of polyether polyol to isocyanate was 1:0.6, the solubility parameter difference between the two was 1.43 (J/cm3)1/2, the intermolecular binding energy was 531.68 kcal/mol, and the two-component system was more stable. A macroscopic direct tensile test was employed to assess the polyurethane elastomers' tensile properties. Our results show that the tensile strength of polyurethane elastomers increased with the increase in isocyanate content and decrease in temperature. Furthermore, the elongation at the break decreased, and the modulus increased, which is consistent with the law of molecular simulation.

Molecular Insight into 6FD Polyimide-Branched Poly(phenylene) Copolymers: Synthesis, Block Compatibility, and Gas Transport Study

A series of 6FDA-DABA (6FD) polyimide and branched poly(phenylene) (PP) block copolymers and homopolymers were successfully synthesized using Diels–Alder and polycondensation reactions. PP and 6FD homopolymer blends in tetrahydrofuran were immiscible. The result coincides with their large chemical dissimilarity and theoretical solubility parameter differences of 25.47 and 33.17 (MJ/m3)1/2. However, 6FD-PP block copolymer solutions were clear, and thin films were robust and creasable. Densities and fractional free volumes (FFV) (0.162–0.346) largely obeyed the rule of mixing, suggesting a “blend-like” morphology. At moderate PP block lengths, two distinct glass transition temperatures (340 and 420 °C) were evident, while large PP block lengths suppressed first-order polyimide transitions entirely. A small-angle X-ray scattering and atomic force microscopy morphological analysis revealed two distinct domains, with separation lengths increasing with the PP block length. Their gas permeation, diffusion, sorption, and separation properties were thoroughly investigated and exhibited a strong correlation with polymer chemistry, block length, and FFV. A block copolymer had an O2 permeability roughly between 6FD and PP, resulting in a 30% increase in O2/N2 selectivity. The N2/CH4 selectivities ranged from 4.2 to 0.58, suggesting that this 6FD-PP system could be efficiently tuned from highly N2-selective to CH4-selective performance. Five structural models, rule-of-mixture, Maxwell, equivalent box model, laminate, and blend, were used to predict gas transport properties. Compared with experimental data, the miscible blend model provided the best results for the 6FD-PP block copolymer system. Block copolymerization by combining highly selective polyimide and highly permeable branched poly(phenylene) provides an opportunity for gas separation tunability and improvement in selected gas pairs.

Thermal conductivity and shear strength characterisation of hybrid GNPs and silane functionalised BN as thermal conductive adhesive

ABSTRACT The demand for high thermal conductivities and improved adhesion of thermal conductive adhesives has heighten the need for hybrid fillers with extraordinary properties, such as boron nitride (BN) and graphene nanoplatelets (GNP) especially at lower filler contents (<20 wt.%), particularly with silane-functionalised BN (fBN) and adhesion using the single lap joints approach. Thus, this study was conducted to measure the thermal conductivity and shear strength of hybrid GNP with BN or fBN at different filler sizes, GNP ratios, and silane coupling agents (KK550 and KH560). We observed that the hybrid GNP/fBN_KH560 composite at a ratio of 0.75 exhibited the highest thermal conductivity and shear strength with enhancements of 198.42% and 81.82%, respectively, attributed by the high compatibility between fBN_KH560 and the polymer matrix, proven by the lowest measured contact angle and Hansen solubility parameter difference. Despite the thermal conductivity value not surpassing that of the single-filled GNP composite, the hybrid composite at lower filler content was considered a success as it exhibited a synergetic effect when compared with single-filled BN or fBN; with the difference of 0.111. Besides, crack deflection, particle debonding and pull-out mechanism improved the shear strength and promoted cohesive failure in the hybrid composite.

Effect of the aramid pulp on the physicochemical, viscoelastic properties and rheokinetics of polyurethanes

This publication highlights the effect of aramid pulp (1 wt.%) on equilibrium swelling, enthalpy reaction, solid viscoelastic properties, and rheokinetics of castor oil (CO) and polyether (PE) polyol blend (50/50 CO/PE) with polymeric isocyanate (pMDI). The CO-pMDI system showed a lower solubility parameter difference (Δδi) than the PE-pMDI and CO/PE-pMDI. Crosslink density values \({v}_{e}\) are higher for CO-pMDI, and when added to aramid pulp, there is a slight increase due to the possible restriction of swollen volume. Regarding the pseudo-solid behavior, AP restricts the macromolecular movement and confers reinforcing characteristics to PU systems. The Prout–Tompkins autocatalytic model satisfactorily described the reactions, resulting in activation energy values Ea within 45 − 54 kJ/mol. However, for the CO/PE blend, the difference between the reactivity of the polyols and the solubility parameter with pMDI results in a two-step reaction kinetics. Aramid pulp practically does not change the reaction mechanism, only the viscosity of the medium. Furthermore, the thermodynamic parameters (ΔS* and ΔH*) indicated that the PU with AP resulted in more ordered complexes. The adequate description of the polymerization reaction and the effect of the aramid pulp allowed for obtaining PU formulations with tunable characteristics for strict composite processing composites.

Molecular Dynamics Study on the Compatibility of Asphalt and Rubber Powder with Different Component Contents.

In order to study the influence of asphalt from different origins on the compatibility of rubber powder and asphalt, the four most representative 90# asphalts from different origins were selected for the four-component test, namely, Karamay, Shell, Esso, and HuanxiLing, which have differences in their microstructure and molecular structure. First, Materials Studio software was used to build the asphalt molecular model based on the four-component test data, and styrene butadiene rubber and natural rubber were used as representative molecules of rubber powder to build the molecular model. The solubility parameters, molecular potential energy, and radial distribution function were obtained by molecular dynamics simulation of rubber powder and four asphalt molecules. The gray correlation degree analysis of the four components of asphalt is carried out with the gray correlation method. The results show that the solubility parameter difference between Esso asphalt and the rubber molecule is the smallest, and the potential energy between them is the largest; that is, the compatibility between Esso asphalt and rubber powder is the best, followed by Shell, Huanxiling, and Karamay. The analysis of the radial distribution function between two molecules also further confirmed the compatibility of the four modified asphalt. The gray correlation degree between the four components of asphalt and the solubility and molecular potential energy index is as follows: saturates > aromatics > resin > asphaltene. It is concluded that the influence of light components on the compatibility of asphalt is greater than that of heavy components. Therefore, in future industrial production, the rubber powder-modified asphalt made of more light components has better performance and storage stability.