Melt Mixing Approach Research Articles

Preparation of agar‐silica nanofilms through melt mixing: Extending beef shelf life through biodegradable packaging

AbstractThe current study used the melt mixing approach to create a variety of agar/SiO2 nanoparticle (AG/Si) nanocomposites films. Silica nanoparticles were included as a filler in different proportions, varying from 0% to 5% (w/w). The study examined how the composition impacted the chemical properties, mechanical characteristics, thermal properties, water vapor barrier, surface color, and antimicrobial capabilities. After the addition of SiO2, the tensile strength increased significantly from 30.77 to 40.97 MPa at 4% SiO2. Moreover, the presence of SiO2 was improved the contact angle from 53.81° to 63.24°, brightness of the film (L*) from 70.63 ± 3.34 up to 84.80 ± 2.26, maximum degradation temperature (Tdmax) from 315 to 317°C and melting temperature (Tm) from 109 to 125°C. In the meantime, following the integration of SiO2 content, the density of agar film dropped from 1.27 to 1.16 kg/m3. The AG/Si film effectively prevented bacterial growth and extended the shelf life of fresh beef, suggesting a novel biobased option for antimicrobial packaging film.

Hybrid carbonaceous filler as promising additives for EMI SE of PVDF-based composites: Comparison between monolayered and multilayered structures

Flexible conducting polymeric composites (CPC) for applications as electromagnetic interference (EMI) shielding materials were successfully prepared by melt-mixing approach using poly (vinylidene fluoride) (PVDF) as the matrix, loaded with hybrid carbonaceous fillers, carbon nanotube (CNT) and graphene nanoplatelets (GNP). Composites with as low as 3 wt% of filler with conductivity values in between 10−3 S/m (PVDF/GNP) and 10−1 S/m (PVDF/CNT) were successfully prepared by using hybrid with different proportions. Multi-layered structure composites displayed significantly higher EMI SE values than the bulk composites, mainly those constituted by CNT and the CNT/GNP (1.5:1.5 wt%) hybrid. By stacking PVDF/CNT, PVDF/CNT/GNP and PVDF/GNP with different arrangements, on can achieve EMI SE around 22 dB (in X-band) and 27 dB (in Ku-band) with absorption contribution of 65–70 % in the X-band and 77–81 % in the Ku-band frequency ranges. The effect of the hybrid composites on the morphological, rheological and thermal properties and on the ability of the β-phase formation on PVDF composites was also investigated. By combining appropriate CNT/GNP ratio, a good compromise between flexibility, conductivity, processability and EM attenuation with absorption characteristics was achieved, thus favoring promising application in stealth technology and also in communication devices.

The influence of metallic particulate inclusions on the mechanical and thermal performance of 3D printable acrylonitrile-butadiene-styrene/thermoplastic polyurethane fused polymer blends

Acrylonitrile butadiene styrene (ABS) shows exceptional mechanical behavior, however, the application of ABS for manufacturing thin parts has been limited because of its significantly lower melt fluidity. Thermoplastic polyurethane (TPU), on the other hand, has acceptable melt fluidity, but its mechanical performance is limited when compared to ABS. This paper combines these two polymers and incorporates elongated iron powder particulates as a reinforcing agent to manufacture a cost-effective yet performance-enhanced blended polymer filament for 3D printing. The melt-mixing approach was followed for blended polymer filament manufacturing. The thermal performance of the extruded filaments was evaluated using differential scanning calorimetry (DSC). The glass transition and melting temperatures were found to be slightly higher for the particulate-reinforced samples when compared to the control unreinforced ABS/TPU blend. This is attributable to the fact that the inclusions limit the mobility of the structure therefore it requires more energy to break down the molecular structure. The tensile strength of the filaments was obtained using a uniaxial tension experiment whereas the fracture toughness of the 3D printed parts was determined using the microindentation technique. The tensile strength and fracture toughness was found to be increasing with an increase in iron powder dosage by up to 5 %. The results reflect that appropriate dispersion of iron particulates is required to achieve the desired performance enhancement. Overall, the findings of this paper can potentially lead to various cost-effective and efficient means for performance enhancement in the manufacturing of 3D printable blended polymer composite filaments.

Glycol lignin/MAH-g-PP blends and composites with exceptional mechanical properties for automotive applications

Lightweight plastics and their composites are being increasingly used in automobiles to reduce emissions and costs, but the market demand for fossil fuel-based plastics such as polypropylene (PP) creates several environmental problems such as pollution and waste. Although replacing PP with biomass such as lignin is not a new endeavor, the vast majority of past studies reported reduced mechanical properties as lignin content increases, which limits its application in industry. Herein, blends of maleic anhydride-grafted PP (MAH-g-PP) and softwood-derived glycol lignin (GL) are successfully fabricated via a melt-mixing approach, which boast exceptional mechanical properties and thermal stability. Synergistic performance enhancement is observed when combined with carbon fiber reinforcement, which is elucidated by nanoindentation of the fiber/polymer interface. This work contributes to the development of sustainable automotive structures by efficiently combining biomass and traditional materials.

CuxCo1-xFe2O4 (x = 0.33, 0.67, 1) Spinel Ferrite Nanoparticles Based Thermoplastic Polyurethane Nanocomposites with Reduced Graphene Oxide for Highly Efficient Electromagnetic Interference Shielding.

CuxCo1-xFe2O4 (x = 0.33, 0.67, 1)-reduced graphene oxide (rGO)-thermoplastic polyurethane (TPU) nanocomposites exhibiting highly efficient electromagnetic interference (EMI) shielding were prepared by a melt-mixing approach using a microcompounder. Spinel ferrite Cu0.33Co0.67Fe2O4 (CuCoF1), Cu0.67Co0.33Fe2O4 (CuCoF2) and CuFe2O4 (CuF3) nanoparticles were synthesized using the sonochemical method. The CuCoF1 and CuCoF2 exhibited typical ferromagnetic features, whereas CuF3 displayed superparamagnetic characteristics. The maximum value of EMI total shielding effectiveness (SET) was noticed to be 42.9 dB, 46.2 dB, and 58.8 dB for CuCoF1-rGO-TPU, CuCoF2-rGO-TPU, and CuF3-rGO-TPU nanocomposites, respectively, at a thickness of 1 mm. The highly efficient EMI shielding performance was attributed to the good impedance matching, conductive, dielectric, and magnetic loss. The demonstrated nanocomposites are promising candidates for a lightweight, flexible, and highly efficient EMI shielding material.

Conductive thermoplastic vulcanizates based on carbon black-filled bromo-isobutylene-isoprene rubber (BIIR)/polypropylene (PP)

Abstract Conductive elastomer materials based on carbon black (CB) filled bromo-isobutylene-isoprene rubber (BIIR)/polypropylene (PP) thermoplastic vulcanizate (TPV) were prepared by two step method and one step method. The microstructure, mechanical properties, electrical resistivity, thermal stability, electromagnetic interference shielding performance, and fracture surface morphology of composite materials were studied. The result shows the serious aggregation of CB in one-step TPV, but the uniform dispersion of CB in two-step TPV. In addition, the two-step TPV shows a higher electromagnetic interference (EMI) shielding performance and lower conductivity penetration threshold. The penetration threshold of the two-step TPV is 9.1%, and the maximum reflection loss of the two-step TPV16 is −29.5 dB. Therefore, this research offers an uncomplicated and scalable melt mixing approach method to manufacture conductive thermoplastic vulcanizates with excellent EMI shielding.

Effect of addition of hydroxyapatite as secondary filler in CNT-reinforced polypropylene hybrid composites

This work entails the effectiveness of hydroxyapatite (HAp) as secondary filler in polypropylene (PP) matrix composites reinforced with HAp-decorated multiwalled carbon nanotubes (MWCNTs). Different composites were prepared through the melt mixing approach. The consequent effect of typical biocompatible ceramic coating on the dispersion of CNTs in a PP matrix and thereby effect on its thermal and mechanical properties have been discussed in this research work. Isothermal hydroxylation technique has been used for the coating of HAp on MWCNTs. It has been observed from the collective information obtained from X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy and field-emission scanning electron microscopy images that HAp constitutes a new phase in the HAp-CNT nanocomposite in the form of a coating of HAp over nanotubes. As a result of which, the use of HAp-coated MWCNTs in PP improved its tensile strength by 38%, modulus of elasticity by 72%, storage modulus by 43% and ductility by around 7.4% in comparison to uncoated MWCNT-reinforced PP composite. However, the coating of HAp shows an insignificant effect for change in temperature-dependent properties of the CNT/PP composites. The improvement in mechanical properties is attributed to the interfacial compatibility between HAp and PP.

Dispersion of graphite nanoplates in melt mixed PC/SAN polymer blends and its influence on rheological and electrical properties

The state of dispersion of two types of graphite nanoplates, namely graphene nanoplates (GnPs) and expanded graphite (EG), in polycarbonate (PC)/poly(styrene-acrylonitrile) (SAN) = 60/40 wt.% blends prepared with a two-stage melt-mixing approach is investigated and its influence on the melt rheological and electrical properties is evaluated. By using two different parameter sets in the first mixing step, different states of the filler dispersion are achieved in the PC. After mixing with SAN, the more stringent premixing conditions (higher mixing speed and longer mixing time) resulted in a lower proportion of visible graphitic structures. The EG achieved a better dispersion than the GnPs. The electrical conductivity is lower for each filler type when the samples show a better dispersion. On the other hand, a better dispersion led to a higher reinforcing effect (as observed in melt rheological studies). By determining the shear dilution exponent and applying the Eilers equation to the rheological results, the strengthening effect and the differences in the state of the filler dispersion between the two premixing conditions were evaluated.

Physical and mechanical properties of polyvinylidene fluoride - Short sugar palm fiber nanocomposites

Abstract The characterization of natural fiber composites has become of paramount importance. The aim of this work is to prepare, produce, and investigate the mechanical, nanomechanical, and physical properties of polyvinylidene fluoride (PVDF) reinforced with short sugar palm fiber (SSPF) composites. Preparation involves successive phases: a melt-mixing approach and a hot/cold compression molding procedure. The mechanical test examines the flexural and tensile strengths. This work introduces nanomechanical testing through the quasistatic nanoindentation to measure the hardness, fracture toughness, stiffness, and Young's modulus. Physical properties are analyzed by measuring the composites' density, water absorption, moisture content, and thickness swelling. Mechanical properties displayed good flexural and tensile enhancements. The use of short fiber led to adequate interfacial bonding between the fiber and matrix. Composites exhibited high compatibility, strength, and a homogenous structure in the fiber-matrix. Nanomechanical test displayed a dynamic modulus mapping on the fiber. The scan line analysis and in-situ scanning probe microscopy (SPM) imaging presented improved hardness, Young's modulus, stiffness, and fracture phenomena. The composites exhibited outstanding physical properties and excellent resistance to water absorption, moisture content, and thickness swelling. The novel findings provide insight on how biocomposite materials can be utilized in various engineering applications. This signifies their high competency and applicability for green production.

Micro‐phase separation kinetics of polyurethane nanocomposites with neural network

Thermoplastic polyurethane elastomers (TPUs) reinforced with multi wall carbon nanotubes (MWCNTs) and Closite30B, were prepared via melt mixing approach and investigated by spectroscopy, and rheological analyses. Following basic analyses, time sweep tests were used to determine the influence of temperature, applied preshear and nanofiller content and aspect ratio on the micro‐phase separation kinetics of the nanocomposites. Based on the experimental results, artificial neural network was developed to explain the relationship between those parameters and micro‐phase separation time. The neural network is able to predict micro‐phase separation time of TPU nanocomposites possessing different nanofillers at various shear rates and temperatures. Comparison between experimental and calculated data by the model shows that the neural network can well‐communicate between input and target variables. POLYM. COMPOS., 40:3904–3913, 2019. © 2019 Society of Plastics Engineers

Enhanced dielectric performance and energy storage density of polymer/graphene nanocomposites prepared by dual fabrication

Polymer/graphene nanocomposites (PGNs) have shown great potential as dielectric and energy storage materials. However, insolubility of graphene in most solvents, hydrophobic behaviour and poor dispersion in polymer matrix restrict wider fabrications and applications of PGNs. In this study, we present co-fabricated PGNs engineered by solution blending and melt compounding methods with improved dielectric performance. Further processing of PGNs by melt mixing after solution blending not only improved dispersion of graphene in the matrix but also ensured good interfacial interaction of the composites’ constituents and reduction of oxygen content in PGNs. Graphene nanoplatelets used in this study was slightly functionalized (fGNPs) to enhance dispersion in the polymer matrix. It was later characterized using Fourier transform infrared (FTIR) and Raman spectrometer. Scanning electron microscope (SEM) was used in morphological study of the fabricated composites. Dielectric properties, electrical conductivity, breakdown strength and energy storage capacity of the fabricated composites were investigated. The results obtained showed well-dispersed fGNPs in poly (vinylidene fluoride) (PVDF) matrix and improved dielectric performance. For instance, with 3.34 wt% and 6.67 wt% fGNPs co-fabricated composites, dielectric constant increased from about 9 for neat PVDF to 9930 and 38,418 at 100 Hz, respectively. While 7588 and 12,046 were respectively measured for solution blended-only composites at similar fGNPs content. These resulted to about 176.9% and 376.4% increase in energy storage density with 3.34 wt% and 6.67 wt% fGNPs co-fabricated composites when compared to their counterparts. These results were also credited to strong bonding, reduction of oxygen and recovered graphene structure by melt-mixing approach.

The Compatibilization Effects of Alkylated-grafted-Graphene Oxide on Polypropylene/Polystyrene Blends

Modified graphene oxide (GO) was synthesized by covalently grafted alkylated chains on GO sheets and their compatibilization effects on the morphologies and mechanical properties of immiscible polypropylene/polystyrene (PP/PS) blends were investigated. Alkylated-grafted-GO/PP/PS batches were fabricated by melt-mixing approach and displayed different morphologies with various modified GO loadings. When the content of alkylated-grafted-GO is 0.2 wt%, the tensile strength of obtained composite could reach 17.97 MPa, showing a 36.3% enhancement compared to that of pristine PP/PS, indicating the positive compatibilization of modified GO in polymer blends. Moreover, the mixing order also plays an important role in achieving the desired improvement in properties. Due to the preferential location of modified GO in PP phase, a favorable “transition zone” could be formed at the interfacial region of two polymers when alkylated-grafted-GO was premixed with PS and subsequently mixed with PP, leading to an improvement of compatibilization between two polymers and an enhancement of mechanical properties. However, serious phase separation and declined tensile strength were obtained with a reversed mixing sequence.

Investigation of mechanical, thermal and surface properties of nanoclay/HDPE nanocomposites produced industrially by melt mixing approach

The main aim of this paper is to introduce mechanical, thermal and surface properties of produced industrially HDPE-based nanocomposites. For this purpose, 1.0, 2.0, 3.0, 4.0 and 5.0 wt.% loading of nanoclay-reinforced HDPE nanocomposites made from the HDPE matrix were prepared by the melt mixing method using a compounder system, which consist of industrial banbury mixer, single screw extruder and granule cutting. The effect of nanoclay on mechanical, thermal and surface properties of nanoclay/HDPE nanocomposites was investigated. The tensile and flexural strength of nanoclay/HDPE nanocomposite increased by about 5% and 7%, respectively, with addition of 1.0 wt.% nanoclay. But then it decreased slightly as the nanoclay content increased to 5.0 wt.%. The tensile modulus and tensile elongation were decreased with the addition of 1.0 wt.% nanoclay, but did not increase further as more nanoclay was added. The flexural modulus of HDPE was significantly improved after (from 1.0 wt.% up to 5.0 wt.%) addition of nanoclay. It was found that the scratch resistance of nanoclay/HDPE nanocomposite improved with addition of the nanoclay by SEM examination. Density, melting flow index (MFI), differential scanning colorimetry (DSC), and vicat softening temperature (VICAT) were used to characterize the physical and thermal properties of the nanocomposites. The X-ray diffraction (XRD), the Fourier transform infrared spectrophotometry (FTIR), and the scanning electron microscopy (SEM) were used to analyze the structural characteristics of the nanocomposites. It is concluded that the addition of the nanoclay in HDPE has significantly influenced the mechanical, thermal, and surface properties of the nanocomposites.

Dispersion of carbon nanotubes into polyethylene by an additive assisted one-step melt mixing approach

This study shows an additive assisted one-step melt mixing approach to produce composites of linear low density polyethylene (LLDPE) with carbon nanotubes (CNTs) which are nearly free of CNT agglomerates. Thereby, the influence of an nonionic additive namely polyoxyethylene cetyl ether as a dispersion additive during the CNT melt mixing process was investigated. It was analysed how the number of the polyoxyethylene repeating units or the exchange of the functional groups affect the dispersion mechanisms of multiwalled carbon nanotubes (MWCNT) namely Nanocyl™ NC7000 in LLDPE. Thereby the supposed CNT dispersion mechanism is explained as schematic overview. In summary, the CNT macrodispersion is improved if the number of polyoxyethylene repeating units increases. Through the addition of polyoxyethylene (20) cetyl ether the percolation threshold can be reduced to about 1 wt.% with a simultaneous homogeneous dispersion of CNTs. Additionally at an MWCNT loading of 2 wt.% and 8 wt.% of polyoxyethylene (20) cetyl ethers the strain at break increases by 113% in comparison to corresponding composite without the additive while modulus and stress at break generally decrease with additive addition.

Electrical and Mechanical Properties of Short-Carbon-Fiber Reinforced Polymerized Cyclic Butylene Terephthalate Composites

Polymerized cyclic butylene terephthalate (pCBT) resin casts filled with short carbon fibers were prepared by the melt-mixing approach. The electrical conductivity of short-carbon-fiber (SCF) reinforced thermoplastic pCBT resin casts were investigated with a special attention paid to the properties in the percolation threshold region and the mechanical properties of the composites were also studied. The percolation threshold value of the novel material system was determined which was also verified by SEM images and the thermoelectric behavior of the specimens. Even though the electrical properties of SCF/pCBT composites enhanced significantly, the material becomes more brittle than neat pCBT and all the specimens appear brittle fracture during the mechanical test. Moreover, fiber pull-out is the main damage form in three-point-bending test.

Performance of different intumescent ammonium polyphosphate flame retardants in PP/kenaf fibre composites

The paper compares the flammability and degradation performance of polypropylene (PP)/kenaf fibre composites under three different intumescent ammonium polyphosphate (APP) flame retardants. Intermeshing co-rotating twin screw extruder melt mixing approach was used to prepare the composites. The initial morphological analysis reveals that twin screw melt compounding has provided an effective homogeneous dispersion and distribution of particles, irrespective of their different particle sizes and surface energies. The thermogravimetry analysis (TGA) proves that the presence of intumescent coating of APP1 improves the thermal stability and decomposition temperature over the others. UL-94V tests and cone calorimeter analysis show that the amount of APP content and the high aspect ratio of the particles are the key factors in obtaining homogeneous flame retardant blend, which tends to decrease sustained combustion and reduce the peak heat release rates of the composites. Morphological analysis of char residue further proves that the cross-linking density of the char provides better insulation for underlying material even though the initial swelling increases the degradation temperature through pronounced blanketing effect. Further analysis using different APP particles recorded competitive mechanical properties.

A successful approach to disperse MWCNTs in polyethylene by melt mixing using polyethylene glycol as additive

An additive-assisted one-step melt mixing approach was developed to produce nanocomposites based on linear low density polyethylene (LLDPE) with multiwalled carbon nanotube (MWCNT). The polymer granules, nanotube powder (2 wt% Nanocyl™ NC7000) and 1–10 wt% of the non-ionic additives poly(ethylene glycol) (PEG) or poly(ethylene oxide) (PEO) with molar masses between 100 g/mol and 100,000 g/mol were simply fed together in the hopper of a small-scale DSM Xplore 15 twin-screw microcompounder. The produced MWCNT/LLDPE composites showed excellent MWCNT dispersion and highly improved electrical properties as compared to samples without the additive, whereas the effects depend on the amount and molar mass of the additive. When 7 wt% PEG (2000 g/mol) were used, a reduction of the electrical percolation threshold from 2.5 wt% to 1.5 wt% was achieved.

Preparation and properties of melt blended metallocene polyethylene/silica nanocomposites: modifier effects

Abstract Metallocene polyethylene (mPE)/silica ternary nanocomposites were prepared via a melt mixing approach using two types of modifiers, mPE-g-MA (maleic anhydride) or linear low density polyethylene (LLDPE)-g-MA. Transmission electron microscopy revealed a similar degree of silica dispersion status for mPE/silica with or without modifiers to suggest the similar compatibility for mPE with modified silica, as evidenced by a similar change on the master curves over the corresponding frequency range and silica content in Cole-Cole plots. Silica and the modifiers served as nucleating agents to increase the crystallization temperature of mPE. Two visible crystallization temperatures or melting temperatures corresponding to mPE and LLDPE-g-MA, respectively, were still observable for LLDPE-g-MA modified cases, but not for mPE-g-MA modified cases. LLDPE-g-MA modified cases rendered the highest Young’s modulus and cutting strength due to the induced yielding from the high crystalline LLDPE-g-MA. Cutting strength of the LLDPE-g-MA modified case was approximately 34% larger than that of the mPE-g-MA modified case at 10 phr silica. By contrast, mPE-g-MA modified cases rendered the highest tear strength due to its high flexibility to provide more physical entanglements. Strength of investigated nanocomposites varied under different deformation behaviors to signify the importance of interphase and matrix variation at similar silica dispersion status.