Hot-melt Process Research Articles

Design of melting parameters for safety airbag labels based on hot air welding technology: CFD simulation and experimental validation

This paper focuses on researching the various factors that influence the material melting rate during the hot air melting process. To achieve this purpose, the paper proposes a melting model for Acrylonitrile-Butadiene-Styrene (ABS) plastic under hot air heating based on Computational Fluid Dynamics (CFD). Orthogonal experiments were conducted based on the parameter range of each factor obtained in the pre-experiment. The results showed that the outlet distance, hot air velocity, hot air temperature, and their interaction items are important factors that affect the melting rate of ABS materials. Based on the simulation results, a multiple nonlinear regression model was constructed to predict the melting rate under different parameters. Comparing the simulation values with the predicted values of the multiple nonlinear regression model, the error between the two was no >10%, indicating the effectiveness of the prediction model. The research results can help guide the hot air welding melting process for different materials and characteristics, and provide a certain reference value for the development of hot air welding technology.

Amphiphilic hot-melt pressure sensitive adhesives for transdermal administration made from low melt-processing temperature OSISO copolymers

Herein, an anionic polymerization method was employed to synthesize a series of amphiphilic poly(ethylene oxide-b-styrene-b-isoprene-b-styrene-b-ethylene oxide) penta-block copolymers (OSISO). Their molecular structure and properties were comprehensively characterized using GPC,1H-NMR, thermodynamic rheological testing and water contact angle test. Notably, the hydrophilic characteristics exhibited a proportional increase with the rise in poly(ethylene oxide) (PEO) content, ranging from 1.3 to 12.6 wt%. The polystyrene blocks with low number-average molecular weight (2000–3500) reduced the copolymer melt viscosity, surpassing a tenfold decrease than the control sample within the temperature range of 50–150 °C. Resultantly, this series of OSISO copolymers could be used to develop amphiphilic hot-melt pressure-sensitive adhesives (HMPSAs) by low temperature hot-melt processing method (<120 °C). HMPSAs loaded with 2 wt% of geniposide, prepared by an optimized composition formula of OSISO copolymers, tackifiers, and plasticizers (in a ratio of 5:5:2), displayed excellent in vitro drug release performance. Additionally, these adhesives presented impressive 180° peeling strength (0.05–0.14 kN/m) without residues left on the substrate in the 180° peeling tests. The incorporation of PEO block significantly enhanced both the adhesive properties and accumulative drug release. Geniposide showed a burst release behavior with a moderate accumulative drug release (15–30 wt%), attributed to the PEO phase without crystallization behavior of long PEO chains.

Preparation and Mechanical Properties of Flexible Prepreg Resin with High Strength and Low Creep.

In this study, aiming at the problem of low strength and high creep caused by medium-low modulus flexible resin based on the formulation design idea of high-molecular-weight epoxy resin (E12)-reinforced flexible epoxy-terminated urethane resin (EUR), a flexible epoxy prepreg resin with high strength and low bending creep was prepared to be suitable for hot melt processing technology. Flexible EUR was synthesized by grafting flexible polyurethane segments onto the epoxy side chain by urethane bonding. By adjusting the ratio of E12 and EUR, the effects of different ratios of the two components on the mechanical properties and viscoelasticity of the resin were systematically studied with dicyandiamide as the latent curing system. Research has found that when the E12 content is between 20%wt and 40%wt, the resin system has the best coating viscosity at 65 °C to 85 °C. The molecular weight and the content of aromatic heterocyclic groups of the resin determine the strength and creep behavior of the resin. When the content of E12 in the system is less than 50%wt, modulus and strength increase linearly, but after more than 50%wt E12 content, the modulus is almost unchanged and the strength begins to decrease. By increasing the content of E12 in the resin, the creep behavior of the resin is greatly reduced. When the content of E12 increases to 50%wt, the bending creep is the lowest.

Nanofiber Ion-Selective Membrane-Coated Carbon Paper All-Solid-State Sensors: One Stone, Two Birds.

Potentiometric sensors with nanostructural ion-selective membranes were prepared and tested. Electrospun nanofiber mats were applied in novel all-solid-state sensors, using carbon paper as an electronically conducting support. For the sake of simplicity, application of a solid contact layer was avoided, and redox-active impurities naturally present in the carbon paper have proven to be effective as ion-to-electron transducers. Application of a nanostructural ion-selective membrane requires an innovative approach to combine the receptor layer with the support. The nanofiber mat portion was fused with carbon paper in a hot-melt process. Applying temperature close to 120 °C for a short time (3 s) allowed binding the nanostructural ion-selective membrane with carbon paper, without significant changes in the nanofiber structure. This process was conveniently performed together with the lamination of the carbon paper support. The thus obtained, potentially disposable sensors were characterized as exhibiting highly reproducible potential readings in time as well as between sensors belonging to the same batch. The benefits of the application of nanostructural ion-selective membranes include shorter equilibration time, lower detection limit, and significantly lower material consumption. However, the nanostructural membrane is characterized by a higher electrical resistance, which is attributed to higher porosity.

An empirical predictive model for determining the aqueous solubility of BCS class IV drugs in amorphous solid dispersions

Context Determining solubility of drugs is laborious and time-consuming process that may not yield meaningful results. Amorphous solid dispersion (ASD) is a widely used solubility enhancement technique. Predictive models could streamline this process and accelerate the development of oral drugs with improved aqueous solubilities. Objective This study aimed to develop a predictive model to estimate the solubility of a compound from the ASDs in polymer matrices. Methods ASDs of model drugs (acetazolamide, chlorothiazide, furosemide, hydrochlorothiazide, sulfamethoxazole) with model polymers (PVP, PVPVA, HPMC E5, Soluplus) and a surfactant (TPGS) were prepared using hotmelt process. The prepared ASDs were characterized using DSC, FTIR, and XRD. The aqueous solubility of the model drugs was determined using shake-flask method. Multiple linear regression was used to develop a predictive model to determine aqueous solubility using the molecular descriptors of the drug and polymer as predictor variables. The model was validated using Leave-One-Out Cross-Validation. Results The ASDs’ drug components were identified as amorphous via DSC and XRD Studies. There were no significant chemical interactions between the model drugs and the polymers based on FTIR studies. The ASDs showed a significant (p < 0.05) improvement in solubility, ranging from a 3-fold to 118-fold, compared with the pure drug. The developed empirical model predicted the solubility of the model drugs from the ASDs containing model polymer matrices with an accuracy greater than 80%. Conclusion The developed empirical model demonstrated robustness and predicted the aqueous solubility of model drugs from the ASDs of model polymer matrices with an accuracy greater than 80%.

Preparation and in-vitro evaluation of single and bi-layered beeswax-based microparticles for colon-specific delivery of mesalamine

Beeswax is selected as a natural coating material for the development of new colon specific drug delivery systems charged by mesalamine. In a first step, beeswax microparticles are prepared using hot-melt process of microencapsulation where drug:beeswax ratio, stirring speed, emulsifier concentration and pH of external phase are varied for the optimization of the drug entrapment and microparticles? morphology. The effect of the nature of the emulsifier is also discussed by studying the hydrophilic?lipophilic balance (HLB) value. In a second step, to obtain delayed delivery systems, bi-layered microspheres are elaborated by the process of emulsion?solvent evaporation using ethylcellulose or cellulose acetate butyrate as outer enteric coating layer. All formulations are characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and optical microscopy. The drug release is established in simulated gastric, small bowel and colon liquids and the release mechanism is discussed by applying the Korsmeyer?Peppas model.

(Invited) Performance Improvement and Potential Applications of Ultrathin Organic Solar Cells

Flexible and thin photovoltaics can supply a variety of applications such as power sources for wearable electronics and soft robots. We reduce the total thickness of such organic photovoltaics down to several μm, which enables extreme bendability and lightweight properties. The important parameters include high efficiency and stability in ambient air conditions. Here we show our recent progress with ultra-thin organic solar cells and potential applications for wearable electronics and soft robots.The current best power conversion efficiency (PCE) for ultrathin organic solar cells is 15.8% reported by ourselves1). We have solved the specific issues behind the usage of ultrathin substrate films to achieve almost comparable PCE with those using normal flexible organic solar cells. One specific technology is the usage of polymer films having good thermal stability and smooth surface roughness2). Another important technology is the development of stable charge carrier injection layers and interfaces at the active layer. The state-of-the-art active layer materials such as PM6:Y6 is known not to be stable in ambient air and other environmental stresses. We verified the degradation occurred by the diffusion of Zn atoms from the conventional electron-transport layer (ETL) of ZnO obtained from the sol-gel process to the active layer, and solved it by replacing the ETL with more stable organic/inorganic hybrid material1,3). Such improved ETL and interface achieved highly balanced performance and stability, enabling good PCE on ultrathin substrates.We improved both PCE and environmental stabilities simultaneously. The stabilities include mechanical robustness3), water-proof property4), thermal stability2), and storage stability in ambient air5). Material development and process engineering enable such improved stabilities. In addition, such environmental stability can offer another practical usage. Our ultrathin solar cells have excellent thermal stability up to 120 ℃. This is capable of the hot-melt process which is a mature technology for the apparel industry. We can adhere our ultrathin organic solar cells directly onto textiles with such hot-melt films without any degraded performances. Apart from the improvement of the performance of ultrathin organic solar cells, we are focusing on how to implement such flexible devices onto three-dimensional surfaces5).We demonstrated some potential applications using our ultrathin organic solar cells used as a power source for wearable sensor applications7,8). We fabricated ultrathin organic solar cell modules and sensors. The sensor was powered by the solar cells under light illumination and monitored electrocardiogram signals with a high signal-to-noise ratio. In addition to this, we also demonstrated rechargeable cyborg insects9). In this research, we adhered our ultrathin organic solar cells onto a living insect abdomen and demonstrated a recharging wireless locomotion control system.We are focusing on both performance improvements of ultrathin organic solar cells and the integration of these cells to supply power to wearable electronics. By accelerating system-level integration research in the next decade to meet the required specifications of appropriate target applications, ultrathin organic solar cells will solve the problems associated with the supply of power for various electronics and will contribute to the overall development of society.1) S. Xiong et al., Adv. Sci. 2022, 9, 2105288.2) X. Xu et al., Proc. Natl. Acad. Sci. 2018, 115, 4589.3) F. Qin et al., Nat. Commun. 2020, 11, 4508 .4) H. Jinno et al., Nat. Energy 2017, 2, 780.5) Z. Jiang et al., Proc. Natl. Acad. Sci. 2020, 117, 6391.6) S. I. Rich, S. Lee, K. Fukuda, and T. Someya, 2022, 34, 2106683.7) S. Park et al., Nature 2018, 561, 516.8) H. Jinno et al., Nat. Commun. 2021, 12, 2234.9) Y. Kakei et al., npj Flex. Electron. 2022, 6, 78. Figure 1

In-situ aligning magnetic nanoparticles in thermoplastic adhesives for contactless rapid joining of composite structures

Magnetic nanoparticles of high magnetic susceptibility, such as magnetite (Fe3O4), have been used for wireless heating of adhesives and composites through the magnetic hysteresis loss mechanism, but the high concentrations of nanoparticles needed to meet heating performance targets can degrade mechanical properties. Herein, we present an in-situ aligning method to enhance the heating efficiency of magnetite nanoparticles in a nylon thermoplastic matrix without adversely affecting its mechanical strength. A composite adhesive was made by dispersing Fe3O4 nanoparticles in a nylon matrix followed by hot melting. Experimental results show that by subjecting the adhesive to an alternating magnetic field during the hot-melt process, its heating rate can be improved by 200% compared to that without applying the magnetic field. The improvement in the heating performance has been identified to stem from the alignment of the ease axis of the magnetic nanoparticles. This in-situ aligning technique enables better induction heating performance with the same amount of Fe3O4 nanoparticles, avoiding the agglomeration problem of high nanoparticle concentrations. Moreover, this technique makes it possible to develop high-performance self-heating thermoplastic adhesive for reversible bonding and self-healing solution with a wide range of applications, such as bonding and debonding of composites, temporary attachment of systems, and recyclable bonded structures.

Hot melt processing strategy to modify eucommia ulmoides gum by click reaction

AbstractUnder the condition of hot melt processing, the modification of eucommia ulmoides gum (EUG) by mercapto compounds, n‐Octyl mercaptan (OM), and isooctyl mercaptoacetate (IOMA) was realized by the click reaction of thiol‐ene. The 1H‐NMR results confirmed that the grafting rate of mercapto compounds was 2.28%–5.30% and 1.68%–3.85% when OM and IOMA reacted with EUG in thiol‐ene click reaction under hot melt processing conditions. The DSC results showed that the crystallinity of EUG‐OM was higher than that of EUG when the amount of grafted compound OM ranged from 0.86 to 1.39 mol%. When IOMA‐modified EUG products change from partially crystalline to amorphous, the critical value of IOMA is 2.15 mol%. With the grafting rate of mercapto compounds increasing, T10, T50, and T90 of mercapto modified EUG has decreased to some extent, the ML, MH, and the difference of MH and ML also decrease at the same time. Compared with unmodified EUG vulcanizate, the hardness and tensile strength of a mercapto compound modified EUG vulcanizate decrease, while the elongation at break significantly increases. The stress‐strain curve of a mercapto compound modified EUG vulcanizate confirmed the transition from rigid crystalline materials to elastomers. This property change should be attributed to the plasticizing effect caused by the crystallization property of the modified EUG. The chemical modification of EUG under solvent‐free conditions is environmentally friendly, and the product is uniform, which may be of great significance for practical industrialization.

Evaluation of shellac‐polyethylene glycol as an alternative material for fabrication of fused filament fabrication 3D printing filament at low extrusion temperature

AbstractThe lack of biopolymer filament has been recognized as a significant challenge to fused filament fabrication (FFF) or fused deposition modeling (FDM) 3D printing. According to the restricted choice, shellac is a natural polymer of interest due to its thermoplastic property at a low temperature. The purpose of this study was to evaluate the feasibility of applying shellac as a candidate biopolymer for FFF 3D printing filaments. Shellac matrices and plasticized shellac matrices of varying grades of polyethylene glycol (PEG) were prepared using hot melt processes, and their physicochemical properties and filament properties were investigated. The results showed that a shellac matrix could be easily prepared at 80°C and stayed stable for up to 12 h. The addition of PEG could improve the stability of the shellac matrix as demonstrated by a slight deviation in acid value, percent insoluble solid, and FTIR spectra after annealing for 24 h. The shellac filaments with acceptable appearance and mechanical properties were also produced at 80 ± 5°C by the incorporation of 10–20% w/w of PEG 4000 or PEG 10000. Therefore, SHL‐PEG might be a good candidate material for the fabrication of 3D printing filament, especially at low extrusion temperature.

A novel ablative material for thermal protection system: Carbon fiber/polysiloxane composites

Fiber reinforced composite materials are widely used in the aerospace industry due to their high strength to weight ratio. One of their applications is as an ablative material placed at the outermost layer of a thermal protection systems (TPS). A TPS requires the ablative material to have low density, low thermal conductivity, high temperature resistance, formation of a stable and high shear strength char. This paper introduces a carbon fiber (CF) reinforced polysiloxane (UHTR) composite material processed and fabricated in a laboratory environment. The fabrication method of this material is illustrated in detail. Thermal, ablation, flammability, and mechanical properties of the CF/UHTR material are characterized and compared to a commercial model ablative material, MX4926. MX4926 is a carbon fiber phenolic (CF/Ph) composite material manufactured by Solvay-Cytec. In this study, the carbon fiber used to make the CF/UHTR material is a PAN-based 8-harness fabric provided by Hexcel. The polymer matrix, UHTR, is a colorless semi-solid polysiloxane resin manufactured by Techneglas LLC. Raw materials are firstly made into CF/UHTR prepreg sheets through a hot-melt process and then compression molded into molding compound (MC) samples or two-dimensional (2D) laminates by a hot press. All samples for testing are post cured in a programmable oven at 350°C for 2 hours. The density of the fully-cured material is measured by the water displacement method. Thermal stability, flammability, and ablation properties of the material (in the format of MC) are characterized using thermogravimetric analysis (TGA), microscale combustion calorimeter (MCC), and oxyacetylene test bed (OTB) with three different heat fluxes. Mechanical properties of the material (in 2D laminates) are measured by a universal testing machine (UTM) to the ASTM standards. Testing results of the CF/UHTR material are compared with the commercial model ablative material, MX4926. Microstructures of the CF/UHTR material before and after mechanical and ablation tests are investigated and compared by an optical microscope and scanning electron microscopy (SEM) to further study the failure mode of the material.

Assessment of Shellac as Alternative Material for Preparation of Fused Deposition Modeling (FDM) 3D Printing Filaments

The objective of this study was to assess feasibility of applying shellac as a biopolymer filament for using in fused deposition modeling (FDM) 3D printing. The shellac matrices were prepared through hot melt process by heating the ground shellac samples at 80°C in a silicone oil bath under continuous stirring for 15 min. Accelerated stability testing (annealing process) was also performed in order to evaluated thermal stability by re-heating shellac matrices at 80 °C for 12 h and 24 h in a hot air oven. The shellac matrices and annealed shellac matrices were then comparatively characterized. In the present study, all shellac matrices were investigated for physical appearance, acid value, insoluble solid, moisture content and also characterized by instrument analysis including Fourier-transform infrared (FTIR) spectroscopy, powder X-ray diffractometry (PXRD) and thermal analysis. The results demonstrated that shellac with initial heat (80°C, 15 min) and annealed at 80°C for 12 h had similar properties except the annealed shellac at 80°C for 24 h which shown the lower acid value and formed insoluble solid. The melting temperature, decomposition temperature and melting enthalpy of shellac were around 63-64°C, over than 200°C and 23 J/g, respectively. Furthermore, the extruded filament based on shellac was achieved by hot melt extrusion (HME) technique. The findings revealed that the shellac properties might be suitable to fabricate FDM filaments.

3D-Drawn Supports for Ion-Selective Electrodes.

A new concept of easy to make, potentially disposable potentiometric sensors is presented. A thermoprocessable carbon black-loaded, electronically conducting, polylactide polymer composite was used to prepare substrate electrodes of user’s defined shape/arrangement applying a 3D pen in a hot melt process. Covering of the carbon black-loaded polylactide 3D-drawn substrate electrode with a PVC-based ion-selective membrane cocktail results in spontaneous formation of a zip-lock structure with a large contact area. Thus, obtained ion-selective electrodes offer sensors of excellent performance, including potential stability expressed by SD of the mean value of potential recorded equal to ±1.0 mV (n = 6) within one day and ±1.5 mV (n = 6) between five days. The approach offers also high device-to-device potential reproducibility: SD of mean value of E0 equal to ±1.5 mV (n = 5).

Application of TPGS as an efflux inhibitor and a plasticizer in baicalein solid dispersion

The oral bioavailability and efficacy of baicalein is dramatically limited by its low solubility and effect of efflux. In our study, we chose PVP-VA64 as a carrier and TPGS as a plasticizer and efflux inhibitor to prepare a solid dispersion of baicalein using hot-melt extrusion technology to improve its solubility and bioavailability. The hot-melt process and formulation were optimized, and a BAC-PVP VA64-TPGS solid dispersion (BPT-SD) was prepared. BAC exists in an amorphous or molecular state in BPT-SD. BPT-SD comprised irregular lumps and small particles without BAC or carrier characteristics. The dissolution efficiency of BPT-SD improved under sink conditions. FTIR showed a strong hydrogen bond between BAC and PVP-VA64 in BPT-SD. BPT-SD maintained good physical stability for 6 months. The apparent permeability coefficient of BAC in the Caco-2 cell model confirmed that BPT-SD had higher gastrointestinal membrane permeability. A rat pharmacokinetic study showed that BPT-SD had higher Cmax and AUC0-24h, shorter Tmax, and 2.88-fold higher bioavailability than BAC. A behavioral experiment in chronic unpredictable mild stress (CUMS) mice confirmed the antidepressant efficacy of BAC. BPT-SD reversed depression-like behavior in CUMS mice and improved BAC bioavailability. BAC preparation into a solid dispersion significantly enhanced dissolution performance and bioavailability.

Surface-Modifying Effect of Zwitterionic Polyurethane Oligomers Complexed with Metal Ions on Blood Compatibility.

To prevent unsolved problems of medical devices, we hypothesized that combinatorial effects of zwitterionic functional group and anti-bacterial metal ions can reduce effectively the thrombosis and bacterial infection of polymeric biomaterials. In this research, we designed a novel series of zwitterionic polyurethane (zPU) additives to impart anti-thrombotic properties to a polyvinyl chloride (PVC) matrix. We have synthesized zPUs by combination of various components and zPUs complexed with metal ions. Zwitterion group was prepared by reaction with 1,3-propane sultone and Nmethyldiethanolamine and metal ions were incorporated into sulfobetaine chains via molecular complexation. These zPU additives were characterized using FT-IR, 1H-NMR, elemental analysis, and thermal analysis. The PVC film blended with zPU additives were prepared by utilizing a solvent casting and hot melting process. Water contact angle demonstrated that the introduction of zwitterion group has improved hydrophilicity of polyurethanes dramatically. Protein adsorption test resulted in improved anti-fouling effects dependent on additive concentration and decreases in their effects by metal complexation. Platelet adhesion test revealed anti-fouling effects by additive blending but not significant as compared to protein resistance results. With further studies, the synthesized zPUs and zPUs complexed with metal ions are expected to be used as good biomaterials in biomedical fields. Based on our results, we can carefully estimate that the enhanced anti-fouling effect contributed to reduced platelet adhesion. Schematic explanation of the effect of zwitterionic polyurethane additives for blood-compatible and anti-bacterial bulk modification.

Simulation and optimization of microlens hot-melting fabricating process based on finite element method

As an important optical element, the microlens array has received more and more attention. Due to the advantages of a short production cycle, low cost, high efficiency, and easy to transfer, the photoresist hot-melting method has been widely used to fabricate microlens. Fabricating microlenses with large aperture and curvature radius are the basic requirements to ensure image quality. However, due to the limitations of photoresist material properties and the hot-melting process, the shape of the microlens is not easy to control. In this paper, the finite element fluid simulation software Fluent was used to simulate the microlens hot-melting fabricating process. Through the simulation, we could understand the formation process of the microlens. By multiple groups of simulation comparison, the key parameter in the formation of microlens was discussed. Besides, the simulation result shows that when a layer of residual photoresist is left around the original photoresist cylinder, microlens with larger diameter can be easily obtained. The experimental results are in good agreement with the simulation results. The comparison imaging experiment also illustrates that the microlens fabricated by the improved process has better imaging ability. Through simulation, this paper not only explains the mechanism of the hot-melting method, but also optimizes its process. The related research could expand the application range of the hot-melting method in the fabrication of microlens.

Heat Treatment Induced Specified Aggregation Morphology of Metoprolol Tartrate in Poly(ε-caprolactone) Matrix and the Drug Release Variation.

Hot-melt blending has been widely used in the pharmaceutical industry to produce drug delivery systems, however, realizing the controlled drug release behavior of a hot-melt blended medicament it is still a tough challenge. In this study, we developed a simple and effective heat treatment method to adjust the drug release behavior, without the addition of any release modifiers. Thin metoprolol tartrate (MPT)/poly(ε-caprolactone) (PCL) tablets were prepared through hot-melt processing, and different morphologies of MPT were obtained by altering processing temperatures and the following heat treatment. MPT particles with different particle sizes were obtained under different processing temperatures, and fibrous crystals of MPT were fabricated during the following heat treatment. Different morphological structures of MPT adjusted the drug diffusion channel when immersed in phosphate-buffered saline (PBS), and various drug release behaviors were approached. After being immersed for 24 h, 7% of the MPT was released from the blend processed at 130 °C, while more than 95% of the MPT were released after the following heat treatment of the same sample. Thus, flexible drug release behaviors were achieved using this simple and effective processing manufacture, which is demonstrated to be of profound importance for biomedical applications.

Nanocrystallisation and self-assembly of biosourced ferulic acid derivative in polylactic acid elastomeric blends

Hypothesis.The crystallisation of biosourced ferulic acid derivatives - Bis-O-feruloyl-1,4-butanediol (BDF) - in a polylactic acid (PLA) matrix produces thermoplastic elastomeric blends that are transparent and biodegradable. Elastomeric and transparency are controlled by the domain size. PLA-BDF blends up to a threshold BDF concentration providing elastomeric properties show no evidence of BDF crystallisation. Heat treatment weakens the PLA-BDF interaction, give BDF molecules mobility to interact with nearby BDF molecules, leading to BDF nano-crystallisation.Experiments.PLA-BDF blends were synthesised by hot-melt processing by mixing pure PLA with different concentrations of BDF (0–40 wt%) at 180 °C for 13 min. One set of blends was annealed at 50 °C for 24 h and compared with the unannealed set. The BDF crystallisation in the blends is studied by combining SAXS, SEM, XRD and Polarised Optical Microscopy. Monte-Carlo simulations were performed to validate SAXS data analysis.Findings.Unannealed PLA-BDF blends of up to the threshold of 20 wt% BDF are dominated by the semicrystalline behaviour of PLA, without any trace of BDF crystallisation. Surprisingly, the PLA-BDF 40 wt% blend shows BDF crystallisation in the form of large and nanoscale structures bonded together by weak interparticle interaction. At concentrations up to 20 wt%, the BDF molecules are homogenously dispersed and bonded with PLA. Increasing BDF to 40 wt% brings the BDF molecules close enough to crystallise at room temperature, as the BDF molecules are still bonded with the PLA network.Annealing of PLA-BDF blends led to BDF nanocrystallisation and self-assembling in the PLA network. Both BDF nanoparticle size and interparticle distance decrease as the BDF concentration increases. However, the number density of BDF nanocrystals increases. The formed BDF nanocrystals have size ranging between 100 and 380 Å with interparticle distance of 120–180 Å. The structure factor and potential mean force confirm the strong interparticle interaction at the higher BDF concentration. Heat treatment weakens the PLA -BDF interaction, which provides mobility to the BDF molecules to change conformation and interact with the nearby BDF molecules, leading to BDF crystallisation. This novel BDF crystallisation and self-assembly mechanism can be used to develop biodegradable shape memory PLA blends for biomedical, shape memory, packaging and energy applications.

A drug delivery system obtained by hot-melt processing of zein plasticized by a pharmaceutically active ionic liquid.

Zein-based filaments containing 20 weight% [Lidocainium][Ibuprofenate] used as a doubly Active Pharmaceutical Ingredient-Ionic Liquid (API-IL) were obtained by extrusion at 130 °C. The plasticizing effect of the active ingredient on the zein amorphous matrix was assessed by differential scanning calorimetry, with a decrease in the glass transition temperature (Tg) from 77 °C, for the raw zein, to 53 °C. After storage under standard conditions (relative humidity 59%, 20 °C) the extrudates were rigid, with a high storage modulus (E') of about 3 GPa at ambient temperature. They had a main mechanical relaxation (Tα) beginning at 55 °C, leading to their flowing at temperatures above 130 °C, as determined by dynamic mechanical analysis, with E' below 1 MPa and tan δ above 1. Their structure was evaluated by wide angle X-ray scattering and NMR analysis was used to evaluate the API-IL stability after thermomechanical processing. Release experiments performed under simulated physiological conditions on filaments evidenced a release of 85% after 7 days immersion. These results demonstrate the advantage of using an API-IL as plasticizer of a resorbable biopolymer. The resulting material can be shaped by a continuous thermomechanical process and used as a drug delivery system.

Hot-Melt Preparation of a Non-Biodegradable Peptide Implant: A Proof of Principle.

Both biodegradable and non-biodegradable peptide-loaded implants are already developed for the long-term treatment of patients, thereby reducing the frequency of drug administration. To further improve peptide formulation, extending the scope of implant-based drug delivery systems towards other polymers and processing techniques is highly interesting. In this study, as a proof-of-principle, the feasibility of hot-melt processing of a peptide active pharmaceutical ingredient was assessed by developing a non-biodegradable poly(ethylenevinyl acetate) (33% VA) implant loaded with 20% (w/w) buserelin acetate. Cross-sectional implant characterization was performed by Raman microscopy. The stability of buserelin acetate in the polymeric matrix was evaluated for 3 months under ICH stability conditions and the quantity as well as the degradation products analyzed using LC-UV methods. An in vitro dissolution study was performed as well and buserelin acetate and its degradants analyzed using the same chromatographic methods. No significant quantities of buserelin acetate-related degradation products were formed during the hot-melt preparation as well as during the stability study. Together with the consistent buserelin acetate assay values over time, chemical peptide stability was thus demonstrated. The in vitro buserelin acetate release from the implant was found to be diffusion-controlled after an initial burst release, with stable release profiles in the stability study, demonstrating the functional stability of the peptide implant. These results indicate the feasibility of preparing non-biodegradable peptide-loaded implants using the hot-melt production method and may act as a proof of principle concept for further innovation in peptide medicinal formulations.