Filler Dispersion Research Articles

Reactive extrusion for efficient preparation of high temperature resistant PA6T/66/BN composites with great thermal management and mechanical properties

High temperature resistant polymer-based composite with high thermal conductivity and great mechanical properties are highly demanded in the field of electronic devices for simultaneously meeting surface mounting process and high-power operation. The key to achieving this goal is to balance the contradiction between the high melt viscosity of high-temperature resistant polymers and the dispersibility of fillers. In this work, the high-performance polyamide 6T/66/hexagonal boron nitride (PA6T/66/BN) composites were fabricated successfully via the method combining prepolymerization and reactive extrusion. Results demonstrated that this method not only significantly improves the preparation efficiency of high temperature resistant polyamide and its composites, but also enables the prepared composites to reach 3.6 W/(m⋅K), over 299 °C and 67.8 MPa in thermal conductivity, melting point and tensile strength respectively. Furthermore, the prepared composite exhibits excellent thermal management effects on LED and CPU. Therefore, the results of this work are of great significance for the efficient preparation and wide application of high-temperature resistant polymer based thermally conductive composites.

The effects of filling method on silicone rubber composites filled with SiO2 and TiO2

Silica (SiO₂) serves as a reinforcing filler, while titanium dioxide (TiO₂) functions as a functional filler, imparting exceptional mechanical strength and UV resistance to silicone rubber. However, compatibility issues may arise when both fillers are incorporated into silicone rubber. This study explores potential solutions through processing methods, specifically by comparing the effects of graded filling and mixed filling on the properties of silicone rubber. Field emission scanning electron microscopy reveals that the mixed filling method promotes a more uniform dispersion of fillers, leading to enhanced performance. Curing tests indicate that the effect of the filling method on the curing processing performance of silicone rubber is negligible. Tensile test results reveal that, compared to the graded filling system, the mixed filling system improves the tensile strength and elongation at break of the silicone rubber composites by 13% and 13.4%, respectively, while simultaneously reducing the Mullins effect, thereby enhancing material stability. Thermogravimetric analysis (TGA) and differential thermal analysis (DTG) results indicate that the uniform dispersion achieved through mixed filling optimizes thermal transfer pathways, resulting in superior thermal stability compared to graded filling. Ultraviolet (UV) spectroscopy results demonstrate that composites containing added TiO₂ exhibit almost zero transmittance in the UV range of 200-400 nm, underscoring their excellent UV resistance; the mixed filling method provides superior UV protection compared to the graded fill method. In summary, for the dual-filler system of SiO₂ and TiO₂, the mixed filling approach enhances filler compatibility by improving dispersion, thereby elevating material performance and broadening potential applications.

Aqueous solution‐assisted in‐situ polymerization for fabrication of BNNS/PA12T nanocomposites with excellent thermal conductivity and mechanical properties

AbstractMaintaining uniform dispersion of nano filler under high content is critical for fabricating polymer‐based composites with great mechanical and thermally conductive properties. In this work, BNNS/PA12T nanocomposite with the highest boron nitride nanosheet (BNNS) content of 23.1 wt% was successfully prepared by the aqueous solution‐assisted in‐situ polymerization method. Results demonstrate that the BNNS can be uniformly dispersed in the composite due to the low viscosity during the polymerization process. As a result, when the content of BNNS is 23.1 wt%, the mechanical properties and thermal conductivity of BNNS/PA12T nanocomposite are 62 MPa and 1.55 W/(m·K). Furthermore, the composites also possess excellent high‐temperature resistance with the coefficient of thermal expansion (CTE) of 60 ppm/°C, about one third of pure PA12T, and the thermal deformation temperature also reaches 139.4°C. Therefore, the fabricated BNNS/PA12T nanocomposite can be effectively applied as thermal management and packaging materials for electronic devices.Highlights BNNS/PA12T nanocomposites were prepared by aqueous solution‐assisted method. BNNS can be uniformly dispersed at the filling content up to 23 wt%. The thermal conductivity of BNNS/PA12T nanocomposite can reach 1.55 W/(m·K). Possessing excellent mechanical properties and dimensional stability. The nanocomposite can be effectively applied for thermal management.

Exfoliating Ti3AlC2 MAX into Ti3C2Tz MXene: A Powerful Strategy to Enhance High‐Voltage Dielectric Performance of Percolation‐Based PVDF Nanodielectrics

AbstractAll‐solid‐state polymer dielectrics benefit from a superior voltage window and conveniently circumvent fire hazards associated with liquid electrolytes. Nevertheless, their future competitiveness with alternative energy storage technologies requires a significant enhancement in their energy density. The addition of conductive 2D MXene particles is a promising strategy for creating percolation‐based nanodielectrics with improved dielectric response. However, a full understanding of the nanodielectric production – microstructure – dielectric performance correlations is crucial. Therefore, this research considered Ti3AlC2 MAX phase and Ti3C2Tz MXene as electrically conductive ceramic fillers in polyvinylidene fluoride (PVDF). Microstructural characterization of both nanodielectrics demonstrated excellent filler dispersion. Additionally, the exfoliation of Ti3AlC2 brought forth extensive alignment and interface accessibility, synergistically activating a pronounced interfacial polarization and nanocapacitor mechanism that enhanced the energy density of PVDF by a factor 100 to 3.1 Wh kg−1@0.1 Hz at 22.9 vol% MXene filler. The stellar increase in the PVDF energy density occurred for a broad MXene filler loading range owing to the unique 2D morphology of MXenes, whereas the addition of Ti3AlC2 fillers only caused a detrimental reduction. Hence, this study buttressed the importance to exfoliate the parental MAX phase into multi‐layered MXene as a decisive strategy for boosting nanodielectric performance.

Preparation and properties of polymer composites filled with modified highly dispersed polyethylene terephthalate

A new method of processing polyethylene terephthalate waste into a highly dispersed polymer filler by chemical treatment in an aqueous ammonia solution has been proposed. The possibility of obtaining highly dispersed polymer filler and polymer composite materials under elevated pressure and temperature by incorporating the filler into an epoxy oligomer has been demonstrated. The size and microphase structure of dispersed modified polyethylene terephthalate were determined using optical microscopy and speckle interferometry. Infrared spectroscopy established the presence of polyamide groups on the surface and preserved polyethylene terephthalate in the center of the particles. The use of 2-(tri-butoxymethyl)oxirane monoepoxide demonstrated that the resulting powder is an active filler and reacts with epoxy groups at elevated temperature, enhancing the strength of the composite after formation. Some operational characteristics of the polymer composites have been determined, and the feasibility of applying the proposed methods to address the disposal of PET containers, including plastic bottles, has been shown. The conditions for producing the fillers, along with the characteristics of the obtained fillers and the polymer composites based on them, have been established.

Dispersion-promoted synergistic cationic dye removal through the co-introduction of natural diatomite and bentonite into chitosan-based hydrogel beads

Hydrogel beads have drawn considerable attention in sustainable wastewater treatment because of their low cost, modifiability, and feasibility. Accordingly, chitosan-based hybrid hydrogel beads were fabricated by incorporating naturally available siliceous micro- and nanoparticles, namely diatomite and bentonite, with different mass ratios. Morphology, swelling behavior, mechanical stability, and ultimately, Methylene Blue (MB)-adsorption performance of the hydrogel beads were comprehensively evaluated in terms of filler dispersion and interactions between the fillers and the matrix. Results revealed that while the simultaneous incorporation of inorganic additives inside the chitosan backbone reduced the swelling degree, the mechanical stability was significantly ameliorated when the 1:1 diatomite-bentonite mass ratio was exploited inside the chitosan matrix. That can be attributed to the well-dispersed fillers and enhanced mechanical entanglements, as well as the strengthened physical interactions between diatomite-bentonite and chitosan matrix. When the hybrid filling system was applied, MB removal efficiency increased synergistically by over 246 % compared to bentonite alone and 268 % compared to diatomite alone, even at low MB concentration (10 ppm). The MB adsorption kinetics and isotherm were also studied. The adsorption kinetics of MB were well-fitted for all compositions using the pseudo-second-order model. The isotherm data for optimum beads indicate that the Freundlich isotherm model provided the best fit, suggesting the multilayer adsorption with a non-uniform distribution of adsorption heat. The cost appraisal and recyclability/reusability assessment indicate that the combination of diatomite and bentonite in chitosan-based hydrogel beads offers a sustainable, highly efficient, and cost-effective solution for cationic dye removal applications.

Geometry Dependent Microwave Absorption Properties in Carbonaceous Materials over X-Band Frequencies (8.2-12.4 GHz) for Stealth Applications

: Carbonaceous materials of two different types, viz. spherical nano carbon black (NCB) powder (Brunauer-Emmett-Teller (BET) surface area ~1400 m2/g) and multiwalled carbon nanotube (MWCNT) (BET surface area ~75 m2/g), have been impregnated in room temperature vulcanized (RTV) silicon rubber matrix to study the effect of geometries of filler particles on microwave absorption characteristics, over X-band frequencies (8.2 -12.4 GHz). The rubber-based composites are prepared by dispersion of NCB and MWCNT fillers in the liquid rubber with loading fractions ranging from 0.3-0.9 wt% and 1.1-1.7 wt%, respectively. The dielectric loss tangent (tanδe) profiles were evaluated for the filler-loaded rubber composites at different concentrations. The calculated Reflection loss (RL) profiles suggest that NCB-based rubber provides maximum RL value, (RL)max ~ -20 dB (99.00 % absorption), at a lower filler concentration of 0.5 wt%, as compared to MWCNT. However, the MWCNT-based rubber composite shows enhanced (RL)min values of ~ -29 dB (~99.99% absorption) due to multiple scattering phenomena. The identified NCB and MWCNT-based rubber-based MW absorbers have potential stealth applications for military aerial vehicles.

Development of Flexible Hydrophobic Polypropylene/SPCB/GNP Hybrid Nanocomposite Films With Excellent EMI Shielding and Mechanical Properties

ABSTRACTThe demand for effective electromagnetic interference (EMI) shielding materials has driven the development of novel and facile approach for fabrication of conductive polymer nanocomposites. In this study, a polypropylene (PP)‐based hybrid nanocomposite was prepared by incorporating Super P conductive carbon black (SPCB) and graphene nanoplatelets (GNP) via latex technology. A simplistic method of fabrication was adopted where the nanofillers were stirred into the PP latex at room temperature, ensuring the proper dispersion of fillers within the matrix. Hybridizing the nanocomposite by the usage of two different fillers has resulted in a substantial improvement in EMI shielding performance of the material along with its mechanical and thermal properties. The samples were fabricated and tested in three different thicknesses to ensure that EMI shielding effectiveness (EMI SE) is a thickness dependent property and also the studies were carried out over a broad range of microwave frequency. A high electrical conductivity of 7.6 S m−1 was obtained and exceptional EMI SE of 65 dB (X band), 69.76 dB (Ku band), and 72.38 dB (K band) was showcased by 2 mm thickness composites. The optical images of PP latex incorporated with the fillers gave a clear understanding about the formation of conducting networks within the polymer matrix at percolation threshold. The addition of SPCB and GNP also showed a significant increase in hardness and tensile strength of the composite and helped in protecting the polymer matrix against photo radiation. The fillers also aided in the enhancement of the hydrophobicity of the films. The thermal stability, crystallization temperature (TC) and melting temperature (TM) of the composites were also improved when compared to that of neat The works aims at fabricating a hydrophobic and low‐density polymer nanocomposite showing excellent absorption dominant EMI SE.

Assessment of the biological durability of oil palm trunk modified with 1,3-dimethylol-4,5-dihydroxy-ethyleneurea (DMDHEU) following subsequent curing at elevated temperatures

The biological durability of oil palm trunk modified with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) was tested after subsequent curing at elevated temperatures. The resistance against mold, decay fungi, and subterranean termites was examined. Dimethylol dihydroxyethyleneurea-modified OPT demonstrated improved resistance against mold and decay fungi; however, the effect was lesser on subterranean termite attacks. Oil palm trunk modified with 34% DMDHEU and cured at 160 °C exhibited the most effective reduction in mass loss due to biological degradation compared to the untreated controls. High curing temperature (> 180 °C) caused cracks and ruptured the cell walls, exposing the untreated zone of the OPT to biological attack. As a non-biocidal wood modification, homogeneous dispersion of DMDHEU with adequate concentration and curing temperature is important to fully prevent OPT degradation by wood-destroying fungi and termites. These results provide valuable information for technologists to enhance or streamline the experimental design of combined modification with DMDHEU and thermal treatment, supporting their practical goals. It is recommended to continue research on the leaching of DMDHEU-modified OPT to understand the prevailing effect of DMDHEU on the biological durability of OPT, whether it is due to cross-linking or filler dispersion.

The influence of filler types and content on the curing behavior and properties of a bio-based polyurethane engineered sealant

Polyurethane (PU) sealants are widely used in practical projects to fill road cracks, extend road life and increase the strength of construction joints. And the fillers not only reinforce the sealant, but also effectively reduce costs. In this paper, a series of experiments were carried out to investigate the effects of filler types and contents on the curing behavior and properties of a novel bio-based PU sealant. Firstly, the optimum filler type was determined by fluorescence microscopy (FM) test and physical properties test. The dispersion of different fillers of different contents in the sealant and its effect on the mechanical properties were determined. Secondly, the effect of fillers on the curing behavior was investigated using Fourier transform infrared spectroscopy (FTIR), gel time experiment and surface drying time experiment. The cross-section surface micro-morphologies of the specimens after tensile tests were analyzed by scanning electron microscopy (SEM). Finally, the viscoelasticity and low-temperature properties were determined using dynamic mechanical analysis (DMA). The high-temperature properties of sealant were investigated using thermogravimetric (TG) analysis. The results showed that precipitated calcium carbonate (PCC) was the best filler. Moreover, fumed silica (FS), as a reactive filler, significantly influences the performance of the sealant. With the increase of filler content, the mechanical and high temperature properties of the sealant were enhanced. And the curing process was accelerated. But the low-temperature performance was reduced. Besides, excessive amount of PCC was worse to its uniform dispersion in the sealant and lead to defections in the materials, reducing the strength of the sealant. The optimum PCC content was recommended to be 10 wt%.

Nanocellulose‐polypropylene composites with novel antimicrobial complex salt

AbstractPolypropylene composites with different contents of zinc‐ammonium salts (3, 5 and 7 wt%) and nanocellulose (1 wt%) after enzymatic bioconversion were characterized by structural, dispersion‐morphological, thermal, antimicrobial and mechanical analysis. It was shown that the use of a newly synthesized salt significantly affected the formation of the supermolecular structure of the polymer matrix and increased the nucleation activity, thermostability and flexibility of the composite materials. Moreover, the addition of the inorganic filler allowed to obtain composites with very good antimicrobial properties against Staphylococcus aureus, Escherichia coli and Candida albicans. An interesting relationship between the degree of filler dispersion in the polymer matrix and the formation of polymorphic varieties was elucidated in the study, which contributes to the improvement of final performance characteristics of composite materials. It is noteworthy that a hybrid filler in the form of nanometric cellulose and a biocidal additive containing zinc‐ammonium complex salt was used for the first time. Research has shown that such polymer composites can find application during the manufacture of smart packaging materials with enhanced barrier properties against oxygen and water vapor as well as improved biocidal characteristics, which will notably extend food storage time. At the same time, the presented process of obtaining the innovative composite materials is an excellent example of sustainable technologies for the design of antimicrobial treatments, while guaranteeing the possibility of further processing of these composite materials through material recycling.Highlights Zinc‐ammonium complex with antimicrobial properties was obtained The strength properties and thermal stability of the composites were improved Degree of filler dispersion in polymer affects formation of polymorphic varieties The composites can be applied in the production of smart packaging materials

Preparation and Performance of PBAT/PLA/CaCO3 Composites via Solid-State Shear Milling Technology

Replacing traditional disposable, non-biodegradable plastic packaging with biodegradable plastic packaging is one of the key approaches to address the issue of “white pollution”. PBAT/PLA/inorganic filler composites are widely utilized as a biodegradable material, commonly employed in the field of packaging films. However, the poor dispersion of inorganic fillers in the polymer matrix and the limited compatibility between PBAT and PLA have led to inferior mechanical properties and elevated costs. In this work, we propose a simple and effective strategy to improve the dispersion of nano-CaCO3 in a PBAT/PLA matrix through solid-state shear- milling (S3M) technology, combined with mechanochemical modification and in situ compatibilization to enhance the compatibility between PBAT and PLA. The impact of varying milling conditions on the structure and performance of the PBAT/PLA/CaCO3 composites was investigated. During the milling process, PBAT and PLA undergo partial molecular chain fragmentation, generating more active functional groups. In the presence of the chain extender ADR during melt blending, more branched PBAT-g-PLA is formed, thereby enhancing matrix compatibility. The results indicate that the choice of milling materials significantly affects the structure and properties of the composite. The film obtained by milling only PBAT and CaCO3 exhibited the best performance, with its longitudinal tensile strength and fracture elongation reaching 22 MPa and 437%, respectively. This film holds great potential for application in the field of green packaging.

Aminated ZIF‐8 to facilitate CO2 sieving through polyvinyl alcohol/ionic liquid membranes

AbstractCO2 separation technology at low pressure is most desirable in carbon capture projects to mitigate global warming. Facilitated transport membranes offer selective and effective CO2 permeation using a wide range of carbon carriers at low pressure. Porous fillers were recently included as they can carry abundant fixed carriers besides offering open channels for CO2 permeation. This study investigates the effects of amine‐modified zeolitic imidazolate framework‐8 (ZIF‐8) with well‐defined micropores and gas sieving ability in polyvinyl alcohol (PVA) membranes containing an ionic liquid that worked as mobile carriers. The effects of amine‐modified ZIF‐8 and silica nanoparticles on membrane properties and separation performance were also compared. Fourier transform infrared spectra confirmed the incorporation of ZIF‐8, secondary amine, IL anions, and silica nanoparticles in PVA membranes. Energy dispersive analysis showed the good dispersion of inorganic fillers. The amine‐modified silica nanoparticles resulted in higher thermal stability compared to the amine‐modified ZIF‐8 in PVA membranes containing [bmin][Ac] ionic liquid, as shown in the thermogravimetric analysis. However, the CO2 separation performance of PVA membranes containing [bmim][Ac] ionic liquid was improved more significantly by the amine‐modified ZIF‐8 with microporous structure. A CO2/N2 ideal selectivity of 85.65 and CO2 permeance up to 4,502.91 GPU were attained. Unlike the CO2/N2 ideal selectivity, the CO2 permeance was not significantly affected either using [bmin][Ac] or [bmin][BF4]. The humid gas greatly enhanced the CO2 permeance without much changes in the CO2/N2 ideal selectivity due to the promotion of facilitated transport. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

In-situ sol-gel process for the formulation of Bis-GMA/TEGDMA/silica dental nanocomposite

A novel dental composite based on Bis-GMA/TEGDMA resin incorporating silica nanoparticles was developed using an innovative in situ sol-gel process. This method ensures a homogeneous dispersion of fillers, effectively preventing their agglomeration during preparation. It results in an interpenetrating network in which polymer chains and silica particles are intimately mixed, thereby enhancing the structural and mechanical properties and minimizing the volumetric shrinkage of the dental restorative material.The formation of organic and inorganic network was confirmed by infrared spectroscopy. The in situ synthesis enabled uniform dispersion of silica nanoparticles within the material as evidenced by transmission electron microscopy, scanning electron microscopy and energy dispersive spectroscopy.The results showed that the prepared composite containing 50 wt% fillers achieved hardness, modulus of elasticity, compressive strength and flexural strength values of 72 HV, 10 GPa, 240 MPa, and 110 MPa, respectively. These properties are comparable to those of the commercial “Nt Premium” composite containing 75 % preformed silica nanoparticles, which has hardness, modulus of elasticity, compressive strength and flexural strength values of 68 HV, 10 GPa, 220 MPa and 95 MPa, respectively. Additionally, the study revealed a significantly reduced volumetric shrinkage of 0.5 % for our composite, compared with over 2.2 % for Nt Premium. This groundbreaking approach holds substantial promise for developing advanced dental materials, offering superior performance and enhanced longevity in clinical applications.

Influence of high cis-1,4-liquid polydienes on properties of carbon-black filled composites

High cis-1,4 liquid polybutadiene (cLBR) and polyisoprene (cLIR) with narrow molecular weight distribution were prepared by the chain-transfer coordination polymerization. The effects of cLBR and cLIR on the physical and dynamic mechanical properties of carbon-black filled composites containing single polybutadiene (PBR) or a blend of PBR/polyisoprene (PIR), were investigated. The results showed that cLBR and cLIR effectively ameliorated filler dispersion compared with the treated distillate aromatic extract (TDAE) oil. The wet skid resistance and rolling resistance of vulcanized PBR/PIR composites plasticized with 5 phr cis-1,4 liquid rubbers were significantly improved. Therefore, a new type of plasticizers cLBR and cLIR that are environmental benign and highly compatible with matrix rubbers, has been discovered to replace the conventional TDAE oil used in fabricating the “green” tyres.

Quantitative Study on Reinforcing Mechanism of Nanofiller Network in Silicone Elastomer Based on Fluorescence Labeling Technology

Although there have been many theoretical studies on the enhancement effect of nanofiller networks and their interaction with elastomer molecular chains on the mechanical properties of elastomers, its mechanism description is still not completely clear. One of the main obstacles is the lack of quantitative characterization techniques and corresponding theoretical models for the three-dimensional morphology of complex nanofiller networks. In this paper, the precipitated silica-filled silicone rubber was studied by fluorescence labeling combined with laser scanning confocal microscopy, and the real three-dimensional images of dispersion and aggregation structure of filled rubber systems were obtained. The microstructure evolution of nano-particle aggregates caused by the increase in the filler volume fraction was quantitatively described, and the reinforcement mechanism of elastomers with a distribution of aggregates and filler networks composed of nanoparticles was studied. Furthermore, a nano-composite reinforcement model based on volume fraction, particle shape, interaction, and filler dispersion has been proposed.

Enhanced Dielectric, Thermal, Energy Storage, Quality Factor, Impedance, and Conductivity Properties of Novel PVDF/PAN/ZrO2 Polymer Nanocomposites for Flexible Electronics Applications

ABSTRACTIn this study, novel polymer nanocomposite films based on polyvinylidene fluoride/polyacrylonitrile/zirconium dioxide (PVDF/PAN/ZrO2) were prepared using a solution casting technique. The structural modifications and morphological properties were analyzed by x‐ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). The obtained results verified the filler‐polymer interactions and uniform dispersion of the ZrO2 filler in the host polymers (PVDF and PAN). Thermal stability of up to 46% leftover residue for 30% ZrO2 nano‐filler loading in the blend polymer nanocomposite was analyzed by thermogravimetric analysis (TGA). The dielectric properties such as dielectric constant and dielectric loss values and impedance, Q‐factor, and AC conductivity were analyzed using an impedance analyzer. The decrement in impedance with increasing nano‐filler content with improved dielectric, thermal, Q‐factor, energy density and conductivity properties signifies the prepared novel PVDF/PAN/ZrO2 polymer nanocomposite as an effective material for flexible electronics applications.

Protective graphene-based coatings for Zamak: Physical and electrochemical analysis

Concerns surrounding the widespread use of hazardous materials have increased over time and have led numerous states to implement regulations aimed at preserving human and environmental health. In response, industries like metallurgy have gradually transitioned from traditional, hazardous technologies to safer alternatives, such as using polymeric coatings to protect metals from corrosion. This study focuses on evaluating the protective properties of non-functionalized graphene oxide-based coating (GC) and functionalized graphene oxide-based coating (FGC) on the zamak samples. First, the powders were analyzed from structural, morphological, and spectroscopic perspectives. The formation of amino-silica groups on the graphene oxide sheets was confirmed through SEM-EDS, XRD, and FTIR analyses, validating the success of the functionalization process. Granulometric analysis demonstrated a good dispersion of fillers in the mixtures. Cross's theoretical model was applied to the rheological experiments to find the optimum way of coating application on metallic substrates. The corrosion resistance of the coatings was evaluated using OCP, LSV, PS, EIS, and salt spray experiments. The results revealed that the functionalized graphene oxide coating provided superior corrosion protection compared to other coatings on Zamak samples. AFM topographic images, along with roughness measurements, indicated a significantly less corroded surface when using the functionalized graphene oxide coating. Additionally, Raman spectroscopy confirmed the protective effectiveness of the FGC coating against corrosion.

INVESTIGATION OF WETTABILITY, ANTIBACTERIAL ACTIVITY, THERMAL INSULATION, AND MECHANICAL CHARACTERISTICS OF ELASTOMER BLEND ADHESIVES WITH HIGH-DENSITY FIBERBOARD WOOD AND ALUMINUM

Attention has recently been given to finding alternative and sustainable raw material sources for wood and metal adhesives, such as polyvinyl alcohol (PVA), corn starch (CS), arabic gum (AG), and dextrins (D). Modifying polymer dispersion using unique substances, such as modifying reactive elastomer liquid (EL) using PVA, CS, AG, or D results in sufficiently moisture-resistant adhesive joins. In the present study, the physical characteristics of EL/blended with the natural polymers PVA, CS, AG, and D, based on high-density fiberboard (HDF) wood and aluminum (Al) adhesives and coatings, were investigated and compared to those of pure EL. The EL was blended with PVA, CS, AG, or D at a ratio of 60/40 (w/w) to form EL/blends. The chemical structures, surface and interface morphology, adhesion strengths (including shear strength and pull-off strength), surface roughness, wettings, color intensity, and thermal insulation of the prepared EL and EL/blends were investigated. A scanning electron microscopy (SEM) investigation confirmed filler dispersion and adhesion between the blends, and coated HDF wood, or Al. The developed EL/AG blend had a pull-off strength of 144±5 and 102±3 MPa and a shear strength of 771±11, and 52±3 N with HDF wood and Al substrate, respectively. The EL/PVA blend had a maximum surface roughness value 4.57 µm, and its average water contact angle (WCA) was 85.6°. A plasma jet was used to treat the surface roughness and hence the wettability of the pure EL and the EL/blends, for example, plasma treatment decreased the roughness of the EL/AG blend from 4.36 to 3.28 μm. WCA, and hence wettability, was also significantly influenced by plasma treatment, for example, plasma treatment decreased the WCA of the pure EL from 71.7±0.4° to 30.7±0.7°. The lightness value of the EL/blends was less than that of the pure EL, indicating that (the color adhesives have darkened). Similarly, the yellowness-blueness and redness-greenness values of the EL/blends were greater than those of the pure EL,( rendering the blended adhesives more reddish and bluish). The EL/AG blend was found to have a minimum thermal conductivity (of 0.27 W/m.K), indicating maximum insulation.

Bioinspired surface modification of mussel shells and their application as a biogenic filler in polypropylene composites

This study explores the potential of mussel shells (MS) as biogenic fillers in polymer composites. The chemical composition and crystal structures of MS were characterised. To improve MS filler dispersion and adhesion within a polypropylene (PP) matrix, three surface modification methods were evaluated: polydopamine (PDA) coating, maleic anhydride-grafted polypropylene (MAPP) modification, and PDA/MAPP co-modification. The PDA coating, inspired by the adhesive properties of mussel foot proteins, successfully functionalized the MS surface, as confirmed by X-ray photoelectron spectroscopy (XPS). Thermodynamic analysis, based on contact angle measurements, revealed that MAPP and PDA/MAPP modifications reduced surface energies and potential energy differences. These changes enhanced filler dispersion and interfacial bonding by increasing hydrophobicity and reducing agglomeration in the PP matrix. Consequently, PP composites with 20% PDA/MAPP-modified MS fillers exhibited a 2.9% increase in tensile strength and a 7.5% increase in flexural strength compared to neat PP. Scanning electron microscopy (SEM) also showed reduced filler-matrix debonding and fewer voids. The proposed mechanism attributes these macroscopic property enhancements to the ability of the PDA coating to facilitate chemical and hydrogen bonding between MS fillers and MAPP.