Melt Compounding Research Articles

(RPh3P)[Mn(dca)3]: A Family of Glass-Forming Hybrid Organic-Inorganic Materials.

ABX3-type hybrid organic-inorganic structures have recently emerged as a new class of meltable materials. Here, by the use of phenylphosphonium derivatives as A cation, we study liquid- and glass-forming behavior of a new family of hybrid structures, (RPh3P)[Mn(dca)3] (R = Me, Et, Ph; dca = dicyanamide). These new compounds melt at 196-237 °C (Tm) and then vitrify upon cooling to room temperature, forming glasses. In situ glass formation of this new family of materials was probed on a large scale using a variable-temperature PXRD experiment. Structure analyses of the crystalline and the glasses were carried out by solid-state nuclear magnetic resonance spectroscopy and synchrotron X-ray total scattering techniques for using the pair distribution function. The mechanical properties of the glasses produced were evaluated showing promising durability. Thermal and electrical conductivities showed low thermal conductivities (κ ∼ 0.07-0.09 W m-1 K-1) and moderate electrical conductivities (σ ∼ 10-4-10-6 S m-1) at room temperature, suggesting that by the precise control of the A cation, we can tune meltable hybrid structures from moderate conductors to efficient thermal insulators. Our results raise attention on the practical use of this new hybrid material in applications including, e.g., photovoltaic devices to prevent light-deposited heat (owing to low κRT), energy harvesting thermoelectric, etc., and advance the structure-property understanding.

Rotomolded polypropylene‐ignimbrite composites: Giving a second life to mineral dust wastes

AbstractThe possibility of rotomolding polypropylene (PP) composites with high loadings of a silica‐based dust of ignimbrite, a byproduct of volcanic stone extraction is demonstrated. This study aims to establish the properties of composites with various ratios of mineral dust as a filler in PP matrices at loadings from 5 to 30 wt%, ultimately transforming mining residues into a valuable resource for composite production and creating a value chain around the traditional mining industry. Once the composites were obtained, they were subjected to several characterization techniques to comprehensively assess their mechanical and thermal properties. In general, a high percentage of ignimbrite powder has resulted in a reduction in the mechanical properties of neat PP, although no significant changes were observed for composites at lower loadings. Furthermore, the incorporation of this mineral material modified the thermal properties of the PP, enhancing its thermal stability. The blending of the matrix and filler resulted in a reduction in both the melting crystallization temperatures for highly‐filled composites. Rotomolded items with good aesthetics, with stone‐like appearance, were obtained without any modification on the mineral dust or even without any melt compounding, therefore not increasing the energy consumption during the composites production.Highlights Composites production is a suitable strategy for valorization of mineral residues. Welded ignimbrite residual dust has been used for the first time in composites. Mineral dust has been successfully used in composites obtained by rotomolding. Polypropylene with up to 30% of the stone dust can be processed. Good aesthetics and mechanical features can be obtained with mineral wastes.

Quantitative predicting physical and spectroscopic properties of silicate laser glasses using a phase diagram approach

AbstractTheoretical prediction of glass compositions with certain performance requirements is a long‐standing challenge in glass research. The difficulty lies in revealing the relationship of glass's composition–structure–property (C–S–P), and establishing a predictive calculation method for glass properties with high accuracy. Here we determine quantitatively the C–S–P relationships of four silicate laser glasses using nearest‐neighboring congruently melting compounds (CMCs) as “component and structural motifs”. For all studied silicate systems, physical properties such as density and refractive index are predicted with an error of less than 5%. Spectroscopic properties, including Judd–Ofelt parameters, fluorescence branching ratio (β), effective bandwidth (Δλeff), emission cross‐section (σe), gain bandwidth, and lifetime, are predicted with an error of less than 10%, with some properties such as β, Δλeff, and σe showing an error of less than 5% in specific systems. Four C–S–P databases have also been constructed, containing detailed physical and spectroscopic properties of over 1200 compositions, facilitating the optimization of glass composition. These findings highlight the significance of nearest‐neighboring CMCs in understanding and developing high‐performance laser glasses.

Effect on Mechanical Property of Polypropylene Mixed with Charcoal Waste Ash through Melt Compounding

This study explores the use of charcoal waste ash, a by-product of human activities, as a filler in polypropylene matrices. The samples were mixed using the melt compounding method using an internal mixer at 1wt%, 2wt%, 5wt%, 7wt% and 10wt%. Tensile strength peaked at 29.85MPa at 2wt% while the flexural strength peaked well above pure PP at 45.5MPa at 7wt%. Charcoal waste ash is possible to enhance the mechanical properties of polypropylene, suggesting its potential as a sustainable material in polymer composites.

Flexible colorimetric sensor for ammonia detection based on polyurethane and bromocresol green

AbstractAmmonia (NH3) is a highly toxic, colorless gas with the potential to cause severe health damage and even fatality. This study aims to develop an inexpensive, flexible, and reversible colorimetric thin film based on thermoplastic polyurethane (TPU), poly (vinyl alcohol) (PVOH) and bromocresol green (BCG) as a colorimetric gas sensor reagent. The fabrication of the sensor films process involves a two-step procedure consisting of melt compounding and compression molding on a laboratory scale. Optimization of the materials composition of the sensor film revealed the optimal concentrations of 0.5 wt% of BCG and 1 wt% of PVOH in the TPU matrix. A visible transition from yellow-orange to green upon exposure to gaseous and liquid ammonia was attributed to the deprotonation of BCG by ammonia nitrogen atom. Furthermore, the sensor exhibited an efficient gas detection limit of 25 ppm and good reversibility for at least 10 exposure cycles. Additionally, the sensor exhibits outstanding selectivity in detecting ammonia over various basic solutions. This study also demonstrates the feasibility of using the proposed system for industrial-scale production as exemplified by the fabrication of filament by continuous extrusion process. The colorimetric filament with diameter of 0.8 mm was successfully weaved onto different cotton fabrics to show their applicability as smart ammonia textile sensors. Graphical abstract

A facile method for carbon nanotube/carbon fiber‐reinforced polylactic acid composites

AbstractThe mechanical strength of polylactic acid (PLA) can be improved by carbon fiber (CF) compositing to expand its application in tissue engineering scaffolds. However, the mechanical strength of CF‐reinforced polylactic acid (CFRPLA) composites is compromised due to weak interfacial interaction resulting from the chemically inert surface of CF. In the article, carbon nanotube (CNT) with poly(diallyldimethylammonium chloride) (PDDA) as a coupling agent was covered on CF to improve the chemical activity and roughness of the surface of CF, and then the as‐prepared CF‐PCNT were further incorporated into PLA via melt compounding. The yield strength, modulus, and thermal conductivity of PLA/CF‐PCNT were 14.09%, 7.65%, and 5.24% higher than those of PLA/CF, respectively, and the volume resistivity was 99.74% lower at a 10 wt% loading. The enhancement for the mechanical properties of PLA/CF‐PCNT composites could be ascribed to the mechanical locking, hydrogen bonds and covalent bonds between CF and matrix through the interface modulation of CNT and PDDA. This facile and non‐destructive method offers a novel strategy for the modification of CF fillers.Highlights CF was modified by PDDA and CNT through a facile and non‐destructive method. The active functional groups and roughness on the surface of CF were increased. The surfaces of CFs were characterized by FT‐IR, Raman spectra, XPS and SEM. The interface was improved by mechanical locking, covalent, and hydrogen bonds. The mechanical strength, electrical and thermal conductivity of composites were improved.

Unveiling the Potential of Halloysite Nanotubes: Insights into Their Synthesis, Properties, and Applications in Nanocomposites

AbstractHalloysite nanotubes (HNTs) have attracted considerable attention due to their unique properties and wide range of applications. This review explores HNT‐based nanocomposites, focusing on their preparation methods and improvements in mechanical, thermal, and barrier properties. Various synthesis techniques, including solution mixing, melt compounding, in situ polymerization, and surface modification, are discussed, along with their benefits and limitations. The role of HNT characteristics such as aspect ratio, dispersion, and surface chemistry in enhancing nanocomposite properties is examined. HNTs significantly boost mechanical properties, including tensile strength, Young’s modulus, and toughness, due to their reinforcement effects. Improved dispersion and interfacial adhesion between HNTs and the polymer matrix enhance these properties. HNTs also act as thermal barriers, improving heat resistance and dimensional stability, while enhancing barrier properties against gases and moisture. These synergistic effects allow for the customization of nanocomposites for specific applications in packaging, automotive, electronics, and biomedical fields. Future research should focus on optimizing synthesis methods and processing techniques to further improve HNT‐based nanocomposites’ performance. This review provides a comprehensive overview of HNT‐based nanocomposites, offering valuable insights for advancing nanomaterials science and engineering.

Excess volume measurements of binary alloy liquids using electrostatic levitation: Magneto-volume effect on positive excess volume.

In this study, we investigate the excess volume (VE) of 24 binary miscible and compound alloy melts using electrostatic levitation. Notably, Pd50X50 (X = Fe, Co, and Ni) and Pt50Fe50 solid solutions with slightly negative or zero mixing enthalpy (ΔHmix) display pronounced positive VE and significantly improved liquid stability after alloying, whereas compound alloy liquids with negative ΔHmix exhibit negative VE. Moreover, the VE of Pd50X50 and Pt50X50 consistently decreases with the increasing number of electrons in X, indicating a magneto-volume effect observed in specific heat measurements. These findings suggest that the formation of excess volume is influenced by both magnetic and thermodynamic contributions.

Growth, Spectroscopic Characterization and Continuous-Wave Laser Operation of Er,Yb:GdMgB5O10Crystal

A transparent Er3+,Yb3+:GdMgB5O10 single crystal with dimensions up to 24 × 15 × 12 mm was grown successfully by the high-temperature solution growth on dipped seeds technique from K2Mo3O10-based solvent. The grown crystal was characterized using PXRD, DSC and ATR techniques. Differential scanning calorimetry measurements and SEM analysis of the heat-treated solids revealed Er,Yb:GdMgB5O10 to be an incongruent melting compound with an onset point of 1087 °C. The absorption edge of the Er,Yb:GMBO sample is located in the region of 245 nm, which approximates a value of 4.8 eV. Absorption and emission spectra, and luminescence kinetics, were studied. The energy transfer efficiency from ytterbium to erbium ions was determined. The laser operation in continuous-wave mode was realized and output characteristics were measured. The maximal output power of 0.15 W with a slope efficiency of 11% was obtained at 1568 nm.

Influence of Green Chemical Treatments on Morphology and Mechanical Properties of Poly(3‐Hydroxybutyrate‐co‐3‐Hydroxyhexanoate)–Agave Americana Fibers Biocomposites

AbstractThis work aims at investigating the effect of two eco‐friendly chemical treatments of Agave Americana fibers (AAFs) on morphology and mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx) biocomposites prepared by melt compounding. Acid citric and sodium bicarbonate treatments are used separately to modify the fiber surface before their incorporation into PHBHHx matrix at 30 wt%. The study reveals through SEM observations that the fracture surface of untreated PHBHHx biocomposite shows a poor fiber‐matrix adhesion with the presence of many microvoids at interface and also some fibers pullout. However, less surface defects with a finer morphology are observed on the treated biocomposite samples resulting in improved tensile and flexural properties compared with neat polymer, being however, more pronounced for those modified with sodium bicarbonate. The study highlights the beneficial effect of the green treatments investigated to enhance the mechanical properties of PHBHHx biocomposites.

Investigations on structure and properties of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) reinforced by diss fibers: Effect of various surface treatments

The paper reports some experimental results on the effect of different chemical modifications of Diss fibers on the properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites involving alkaline, combined alkaline/peroxide and combined alkaline/silane treatments. The biocomposite samples loaded at 20 wt% were prepared by melt compounding. Scanning Electron Microscopy (SEM) showed a better fiber-matrix interaction between Diss fiber and matrix after surface fiber treatment. Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD) results indicated an increase in crystallinity index of the biocomposites. In addition, the incorporation of Diss fibers treated with alkali-silane resulted in an improvement in Heat Deflection Temperature (HDT) and shore D hardness from 141.1 °C and 75.1–145.7°C and 86.2, respectively, in comparison with the neat matrix. This also agreed with the flexural properties results, which showed a significant increase in flexural modulus by almost 30 % compared to the neat PHBV. The same trend was observed for water absorption. Overall, combined alkali-silane treatment was found to be most efficient surface treatment method to develop strong interfacial adhesion between PHBV and Diss fiber, increasing the scope of application in manufacturing of light weight green composites.

Melt Compounding of Poly(lactic acid)-Based Composites: Blending Strategies, Process Conditions, and Mechanical Properties.

Polylactic acid (PLA), derived from renewable resources, has the advantages of rigidity, thermoplasticity, biocompatibility, and biodegradability, and is widely used in many fields such as packaging, agriculture, and biomedicine. The excellent processability properties allow for melt processing treatments such as extrusion, injection molding, blow molding, and thermoforming in the preparation of PLA-based materials. However, the low toughness and poor thermal stability of PLA limit its practical applications. Compared with pure PLA, conditions such as processing technology, filler, and crystallinity affect the mechanical properties of PLA-based materials, including tensile strength, Young's modulus, and elongation at break. This review systematically summarizes various technical parameters for melt processing of PLA-based materials and further discusses the mechanical properties of PLA homopolymers, filler-reinforced PLA-based composites, PLA-based multiphase composites, and reactive composite strategies for PLA-based composites.

Melt compounding of spray-dried cellulose nanofibrils/polypropylene and their application in 3D printing

Micro- and nano-scale cellulosic fillers exhibit excellent dispersion and distribution within a thermoplastic matrix during the process of melt compounding or injection molding. In this study, spray-dried cellulose nanofiber (SDCNF) powders were manufactured using a pilot-scale rotating disk atomizer spray dryer. Bleached Kraft pulp (BKP), unbleached Kraft pulp (UKP), and old corrugated cardboard pulp (OCC) fibrillated at a fines level of 90% were used as feedstock materials for spray-drying. BKP-, UKP-, and OCC- SDCNFs were compounded with polypropylene using a twin screw co-rotating extruder. Maleic anhydride grafted polypropylene (MAPP) was used as a coupling agent in the composite formulations. The tensile, flexural, and impact properties of SDCNF-filled PP composites increased at 10 wt% SDCNF loading. The presence of SDCNFs in the PP matrix resulted in faster crystallization and a 12% reduction in the degree of crystallinity of the neat PP. The coefficient of thermal expansion (CTE) of neat PP was reduced by up to 31% attributable to the presence of the SDCNFs. Application of the SDCNF-reinforced PP composites in 3D printing reduced the shrinkage rate of the printed neat PP by 39%, and the printability of the PP was significantly improved with the addition of the SDCNFs.

Properties of La2F4Se, B–LaFSe phases. Phase diagram of the LaF3–La2Se3 system

Lanthanum selenidofluorides belong to wide-gap semiconductors and are promising for optoelectronics. La2F4Se, B–LaFSe compounds were obtained by the ampoule method from binary compounds. Crystals La2F4Se, R-3m, a = 4.18245(11) Å, c = 23.2939(6) Å, Z = 3, B–LaFSe P63/mmc, a = 4.21989(5) Å, c = 8.19140(10) Å, Z = 2 have a layered grain structure, their microhardnesses are 340 and 450 HV, which allows samples processing. The optical bandgap of La2F4Se is 4.5 eV. The optical bandgaps of La2F4Se and B–LaFSe were analyzed by comparing the calculated absorption spectra and the experimental Kubelka-Munk Functions. It was shown that this approach is attractive in explaining optical properties in the vicinity of fundamental absorption onset and in neighboring regions. In LaF3–La2Se3 system, temperatures and enthalpies of five phase transformations were determined, and their balance equations were obtained. It was shown that La2F4Se, B–LaFSe compounds melt incongruently and that an eutectic is formed between the phases. A phase diagram of LaF3–La2Se3 system was constructed. The liquidus calculated by Redlich-Kister polynomial agrees with the data of differential scanning calorimetry.

Investigating Anti-Bacterial and Anti-COVID-19 Virus Properties and Mode of Action of Pure Mg(OH)2 and Copper-infused Mg(OH)2 Nanoparticles and Coated Polypropylene Surfaces

Robust anti-microbial surfaces that are non-toxic to users have widespread application in medical, industrial, and domestic arenas. Magnesium hydroxide has recently gained attention as an anti-microbial compound that is non-toxic, biocompatible, and environmentally friendly. Here we demonstrate melt compound and thermally embossed methods for coating polypropylene with Mg(OH)2 nanoplatelets and copper-infused Mg(OH)2 nanoplatelets. Polypropylene articles coated with Mg(OH)2 nanoplatelets and copper-infused Mg(OH)2 nanoplatelets exhibit a log 8 kill of E.coli within 24 hours. In addition, Mg(OH)2 NPs suspension, at 0.25% reduced SARSCoV-2 virus titers in the solution by 2.5 x 103 PFU/mL or 29.4%, while the Cu-infused Mg(OH)2 NPs suspension, at 0.25% reduced titers by 8.1 x 103 PFU/mL or 95.3%. Fluorescence microscopy revealed that reactive oxygen species (ROS) are produced in bacteria in response to Mg(OH)2 and Cu-infused Mg(OH)2 nanoplatelets which appears to be an important but not the sole mode of anti-microbial action of the nanoplatelets. Plastics with anti-microbial surfaces from where biocides are non-leachable are highly desirable. This work provides a general fabrication strategy for developing anti-microbial plastic surfaces.

Enhancement of Polystyrene Nanocomposites with THDACl-Modified Montmorillonite via Melt Compounding

Enhancement of Polystyrene Nanocomposites with THDACl-Modified Montmorillonite via Melt Compounding

Investigation of physical, thermal, mechanical and gas permeability properties of low‐density polyethylene/ poly(4‐methyl‐1‐pentene) blend films and their utilization for fresh‐cut fruit and vegetable packaging applications

AbstractIn this study, low density polyethylene/poly(4‐methyl‐1‐pentene) (LDPE/PMP) blend films were prepared by melt compounding in a twin‐screw extruder then film casting in a single screw extruder equipped with a cast‐film. Morphological, thermal, and mechanical properties of flexible blend films were characterized by XRD, SEM, DSC analysis, and tensile tests. Solid‐state viscoelastic properties of samples were also quantified by measuring creep behaviors in DMA. Oxygen and carbon dioxide permeability values of films were measured. Their packaging film application performances were evaluated by observing the textural properties of fresh‐cut bananas stored into LDPE and a blend film bag and monitoring the ethylene, oxygen, carbon dioxide concentrations into the bags for 14 days. It was found that LDPE/PMP blends showed partially miscible structure but yielded highly transparent films. DSC results pointed out that the PMP significantly reduced the degree of crystallinity value of LDPE. On the other hand, PMP improved tensile strength and elastic modulus of LDPE. Creep tests indicated that the PMP addition significantly reduced the creep resistance and relaxation time of LDPE. This study clearly signified that the PMP dramatically increased the oxygen permeability value of LDPE. It has also been concluded that LDPE/PMP blend films can be used as a highly permeable packaging material for successfully extending the shelf life of fresh‐cut fruits and vegetables.Highlights LDPE/PMP films, despite being partially miscible, are highly transparent and made through melt compounding and film casting. Adding PMP to LDPE reduces crystallinity but improves tensile strength and elasticity, as shown by DSC tests. PMP reduces LDPE's creep resistance and quickens relaxation time, according to DMA creep tests. PMP greatly increases LDPE's oxygen permeability, ideal for gas‐transmitting packaging. LDPE/PMP film packaging prolongs the shelf life of fresh produce, proven in a banana storage study.

Biobased Composites of Poly(Lactic Acid) Melt Compounded with Bacterial and Vegetal Nanocelluloses Incorporated through Different Strategies.

In the current contribution, bacterial nanocellulose obtained from a by-product of Kombucha tea production and vegetal nanocellulose isolated from milled rice husks were employed as fillers of PLA-based composites prepared by intensive mixing followed by compression molding. Given the challenges associated with the incorporation of nanocelluloses-initially obtained as aqueous suspensions-into melt compounding processes, and also with achieving a proper dispersion of the hydrophilic nanofillers within PLA, three different nanofibrils incorporation strategies were studied: i.e., direct mixing of dried milled nanocelluloses and PLA; masterbatching by solvent casting of native nanocelluloses followed by melt compounding; and masterbatching by solvent casting of acetylated nanocelluloses followed by melt compounding. Composites with varying filler content (from 0.5 wt.% to 7 wt.%) were characterized in terms of morphology, optical properties, and mechanical performance. Results revealed the relative suitability of each strategy employed to promote nanocelluloses dispersion within the PLA matrix. PLA/nanocellulose masterbatches prepared by solvent casting proved to be particularly useful for feeding the nanocelluloses into the processing equipment in a dry state with limited hornification. Acetylation also contributed to a better dispersion of both nanocelluloses within the PLA matrix, although no clear positive impact on the mechanical properties of the films was observed. Finally, filler loading played an important role in the films' properties by increasing their stiffness while reducing their translucency.

Effect of Sugarcane Bagasse, Softwood, and Cellulose on the Mechanical, Thermal, and Morphological Properties of PP/PE Blend

The usage of cellulosic fibers as fillers for thermoplastics has generated great interest due to their numerous advantages and benefits compared to conventional fibers. This article examines a comparative study on the mechanical, thermal, and morphological properties of polypropylene/polyethylene (PP/PE)/cellulose (sugarcane bagasse (SCB) and softwood (SW)) blend composites prepared through melt compounding. The morphology of the obtained PP/PE/SCB and PP/PE/SW blend composites was investigated using scanning electron microscopy (SEM). The X-ray diffraction (XRD) analysis showed reduced crystallinity of the PP/PE blend after fiber interaction. Thermal results showed that the PP/PE/SW blend was more thermally stable compared to the PP/PE/SCB blend. Additionally, the onset temperature of main degradation decreased with th e incorporation of extracted celluloses. Differential scanning calorimetry (DSC) analysis revealed that the introduction of SCB or SW raw fiber and extracted celluloses did not significantly change the melting and crystallization behavior of the PP/PE blend. Dynamic mechanical analysis (DMA) revealed that the storage modulus of the PP/PE/SCB raw and PP/PE/SW raw materials were lower than their corresponding cellulose blend composites across the temperature range studied.

Study on Influencing Factors on Properties of Injectional Compounds Based on Polyethylene and Silica from Waste Materials

"In this study, silica from waste materials - rice husk (silica TT) and byproduct of quartz stone grinding (silica TA) - modified with bis (3-ethoxy propylsilane) tetrasulphide (TESPT) were characterized. Their particle sizes are mostly under 30 μm, quite suitable for plastic filling. Some factors influencing the properties of injectional compounds based on HDPE/LDPE blend and silica from waste materials were carried out. It was found that the processing conditions which including maximum temperature of 190-200 oC and screw speed of 50-100 rpm are suitable for stable compound properties. Processing aid additives ratios such as stearic acid/zinc stearate and PE wax/paraffinic oil affect mostly compound melt flow index, but HDPE/LDPE ratio strongly affects both melt flow index and mechanical properties of compounds: change HDPE/LDPE ratio from 90/10 to 60/40 decrease tensile from 15.2 MPa to 12.5 MPa, bending strength from 15.5 MPa to10.6 MPa while melt flow index decrease almost twice but elongation at break increase from 34.4% to 72.2%. Also, using PE-g-MA as a compatibilizer may remarkably enhance the mechanical properties of compounds: the PE-g-MA content of 0.8-1.0 (%wt) increases tensile, bending strength, and impact resistance of compound by about 10-30% in comparison with the compound without PE-g-MA. "