PP Samples Research Articles

Analysis and removal of bisphenols in recycled plastics using polyethylene glycol

This study examines the presence of bisphenol A (BPA), S (BPS), F (BPF), and M (BPM) in various recycled plastics readily available on the market (LDPE, HDPE, PET, and PP), in light of European Food Safety Authority (EFSA) limits. Twenty samples of different origin are analyzed, cleaning treatments are applied, and the migration potential of these bisphenols into food is studied. BPM is absent in all samples, but a post-consumer recycled LDPE sample reveals high bisphenol concentrations, raising concerns, reaching 8540 ng/g, 370 ng/g, and 29 ng/g of BPA, BPS, and BPF, respectively. Migration tests show substantial migration of these contaminants into food simulants. Using a cleaning treatment with polyethylene glycol (PEG 400) reduces BPA in LDPE, HDPE, PP, and PET samples by 95%, 99%, 97% and 28%, respectively, highlighting the importance of cleaning treatments across various polymers in plastic recycling. These findings not only protect food safety but addressing environmental challenges associated with plastic recycling.

PVA/whey protein nanofiber-coated PP melt blown integrated with Pickering emulsion of citral stabilized for potential medical applications

As an antibacterial agent with pleasant fragrance, citral (CIT) indicates hydrophobic character, and therefore has low water solubility. In this study, Pickering emulsions were formed and polyvinyl alcohol (PVA)/whey protein hydrophilic nanofibers were coated on PP melt blown non-woven surfaces by electrospinning method. In this context, hydrophobic citral essential oil is stabilized with β-cyclodextrin (β-CD) in the electrospinning process. PVA and whey protein polymer blend were used as nanofiber matrixes. The morphological, physical, and thermal properties of the β-CD/citral complexes were investigated in PVA/whey protein nanofiber-coated PP non-wovens at various β-CD levels (1:2, 1:4 and 1:6). Furthermore, zone inhibition procedure was performed to evaluate antibacterial activity of the samples against Gram (+) (Staphylococcus aureus ATCC® 25923) and Gram (-) (Escherichia coli ATCC® 25922, and Pseudomonas aeruginosa ATCC® 27853) bacteria. The morphology of fibers showed that all obtained nanofiber-coated PP surfaces were in the range with 216 - 330 nm average fiber diameter. Fourier Transform Infrared (FT-IR) and thermal gravimetric analysis (TGA) thermograms revealed that citral were successfully integrated into the bio-based nanofibers. As the amount of citral increased (i.e., the β-CD/citral increased), the thermal resistance of bio-based nanofiber coated PP surfaces increased. Antibacterial activity indicated the citral-loaded nanofiber-coated PP surfaces were most effective against Escherichia coli, while none of the samples have antibacterial activity against Pseudomonas aeruginosa. Overall, the results displayed that the fabricated PVA/whey protein nanofiber-coated PP samples integrated with Pickering emulsion of citral stabilized have promising wound dressing applications.

Differences in the Residual Behavior of a Bumetrizole-Type Ultraviolet Light Absorber during the Degradation of Various Polymers.

The alteration of an ultraviolet light absorber (UVA: UV-326) in polymers (PP, HDPE, LDPE, PLA, and PS) over time during degradation was studied using an enhanced degradation method (EDM) involving sulfate ion radicals in seawater. The EDM was employed to homogeneously degrade the entire polymer samples containing the UVA. The PP and PS samples containing 5-phr (phr: per hundred resin) UVA films underwent rapid whitening, characterized by the formation of numerous grooves or crushed particles. Notably, the UVA loss rate in PS, with the higher glass transition temperature (Tg), was considerably slower. The behavior of crystalline polymers, with the exception of PS, was analogous in terms of the change in UVA loss rate over the course of degradation. The significant increase in the initial loss rate observed during EDM degradation was due to microplasticization. A similar increase in microplasticization rate occurred with PS; however, the intermolecular interaction between UVA and PS did not result in as pronounced an increase in loss rate as observed in other polymers. Importantly, the chemical structure of UVA remained unaltered during EDM degradation. These findings revealed that the primary cause of UVA loss was leaching from the polymer matrix.

Antibacterial Ability of Seaweed Endophytic Bacteria (Turbinaria ornata, Sargassum crassifolium, and Sargassum polycystum) Against Skin Disease Agents

Bioactive substances that can prevent the growth of pathogenic germs can be produced by endophytic bacteria This study aims to identify seaweed endophytic bacteria (Turbinaria ornata, Sargassum crassifolium, Sargassum polycystum) and their potential antibacterial activity against skin disease agents (Staphylococcus aureus and Staphylococcus epidermidis). In February 2023 (the rainy season), seaweed was harvested from the waters off Panjang Island in Jepara Regency, Central Java, Indonesia. Endophytic bacterial isolates that had been effectively isolated and purified were directly tested for antibacterial activity. Three isolates with the best antibacterial activity were extracted using the ethyl acetate solvent. The extract samples will be put through additional antibacterial testing using the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and paper disc diffusion procedures. Using the thin layer chromatography (TLC), the class of chemical components in the extract was determined. A molecular technique based on the 16s rRNA gene (1,400 bp) was used to identify endophytic bacterial isolates. Three species of seaweed yielded 25 isolates of endophytic bacteria: 11 from T. ornata, 7 from S. crassifolium, and 7 from S. polycystum. To.09.pp, To.10.pp, and Sc.06.pp were the 3 isolates with the highest antibacterial activity in the direct challenge test. Zone of inhibition results from subsequent antibacterial testing using paper disc diffusion ranged from medium to very strong intensity. To.10.pp sample’s MIC test yielded the best results, with S. aureus and S. epidermidis concentrations of 937.5 and 1,875 µg/mL, respectively. MBC test yielded the highest findings, with S. aureus and S. epidermidis concentrations of 1,875 and 1,875 µg/mL, respectively. The To.10.pp sample yielded terpenoids, alkaloids, and flavonoids, according to TLC analysis of chemical constituent groups. Acinetobacter indicus strain 80-1-2 and Vibrio harveyi strain B14-1 were identified as potential endophytic bacteria from T. ornata, and Acinetobacter indicus strain 80-1-2 from S. crassifolium. HIGHLIGHTS Endophytic seaweed Turbinaria ornata, Sargassum crassifolium, and Sargassum polycystum showed antibacterial activity against Staphylococcus aureus ATCC 29213 and Staphylococcus epidermidis FNCC 0048 Acinetobacter indicus strain 80-1-2, and Vibrio harveyi strain B14-1 were all successfully identified by molecular analysis as potential endophytic bacteria Identification of compounds using Thin Layer Chromatography (TLC) showed the presence of terpenoids, alkaloids, and flavonoids GRAPHICAL ABSTRACT

Tomographic and Tension Analysis of Polypropylene Reinforced with Carbon Fiber Fabric by Injection Molding.

The use of thermoplastic materials has had significant growth in recent years. However, with great mechanical requirements, thermoplastics have limitations to their use. To improve these restrictions, these materials are reinforced to obtain better properties. Polypropylene is one of the most versatile polymers and is used in almost all modern industries. Thus, the aim of this study is to create composite materials that offer performance for various industrial fields using carbon fiber fabric reinforcement, which is an inexpensive material widely used by the aerospace, automotive, and marine industries. The samples are produced by the over-injection molding of polypropylene. The investigation is focused on the impact of two critical control parameters in the injection molding process: temperature and pressure. Twelve experiments have therefore been considered, taking into account the combination of three factors: the presence or absence of carbon fiber fabric reinforcement, three levels of temperature (200 °C, 220 °C, and 240 °C), and two injection pressures (5000 kPa and 10,000 kPa). To evaluate the influence of these factors, three analyses were carried out: first, on the samples' shrinkage using a portable metrology-grade 3D laser scanner; second, on the internal defects using computed tomography (CT); and third, on the mechanical properties with tensile tests. From the results obtained, it is observed that the mold shrinkage fell slightly when PP samples were reinforced with carbon fiber, with both materials (PP and carbon-fiber-reinforced PP) having linear behavior with temperature. It is also noticed that polypropylene behaves as a crystalline material when processed at higher temperatures and pressures. From tests on the mechanical properties, it is concluded that the mean yield strength of PP-CF for injection temperatures of 220 °C and 240 °C represents an increase of 43% compared to the non-reinforced material.

Biodegradation of additive-free polypropylene by bacterial consortia enriched from the ocean and from the gut of Tenebrio molitor larvae

Accumulation of highly recalcitrant PP wastes has caused a serious environmental pollution. We evaluated the biodegradation of two types of additive-free PP polymers by microbial degraders from different environments. Two bacterial consortia, designated as PP1M and PP2G, were enriched from the ocean and from the guts of Tenebrio molitor larvae. Both consortia were able to utilize each of two different additive-free PP plastics with relatively low molecular weights (low molecular weight PP powder and amorphous PP pellets) as the sole carbon source for growth. After a 30-day incubation, several plastic characterization methods, including high-temperature gel permeation chromatography, scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry, were used to characterize the PP samples. The bio-treated PP powder was covered with tight biofilms and extracellular secretions with significantly increased hydroxyl and carbonyl groups and slightly decreased methyl groups. This suggested that degradation and oxidation had occurred. The altered molecular weights and the increased melting enthalpy and average crystallinity of the bio-treated PP samples all suggested that both consortia preferred to depolymerize and degrade the fractions with molecular weights of ≤34 kDa and the amorphous phase fractions of the two types of PP. Furthermore, low molecular weight PP powder was more susceptible to bacterial degradation compared to amorphous PP pellets. This study provides a unique example of different types of additive-free PP degradation by different culturable bacteria from the ocean and insect guts as well as a feasibility of PP waste removal in different environments.

Investigation of Pungamia Oil Properties Using Spectroscopy for Transformer Applications

Traditionally, the insulating oil’s characteristics are measured by analyzing various properties such as electrical, chemical, and physical properties. Because these methods are lacking accuracy, the spectroscopy analysis has been incorporated with conventional testing for assessing the critical properties of proposed non-edible Pungamia oil (PP) as a biodegradable insulating oil for transformer. The results are evident that PP oil’s critical characteristics are meeting the standard requirement as an insulating material for the transformer applications. DGA analysis illustrates that the combustible gas emission on mineral oil is higher than that of PP samples. From FTIR and UV–VIS analyses it is observed that the thermal withstanding ability of PP is well comparable to that of mineral oil. SEM analysis revealed that the deterioration rate of cellulose-insulating material immersed in PP is lower than that immersed in mineral oil. XRD analysis proved that crystallite reduction in mineral oil immersed cellulose-insulating material is higher than the ester oil. Abbreviations: CH4: methane; C2H2: acetylene; C2H4: ethylene; C2H6: ethane; CO: carbon monoxide; CO2: carbon dioxide; DGA: dissolved gas analysis; FTIR: Fourier transform infra-red spectroscopy; H2: Hydrogen; MO: mineral oil; NEO: natural ester oil; PO: Pungamia oil; SEM: scanning electron microscope; UV: Vis-Ultraviolet–visible spectroscopy; XRD: X-ray diffraction analysis

Elucidating the mixing effect of dual polymers via physical blending on its physicochemical, thermal and electrical properties for dye-sensitized solar cells

Blending two different polymers through a physical blending is a wise alternative to create a new polymer with desired properties showing a synergistic effect of the individual polymers. In this work, polyacrylonitrile (PAN) and poly (1-vinylpyrrolidone-co-vinyl acetate) P(VP-co-VAc) were blended in a fixed amount of binary organic solvent of ethylene carbonate and propylene carbonate. The weight ratios were varied to 30:70, 50:50 and 70:30 wt%, respectively. Polymer electrolytes in a gel and solid form are safer than liquid ones. Thus 50:50PP and 70:30PP samples were selected and incorporated with iodide/triiodide redox mediators such as sodium iodide salt, 1-methyl-3-propylimidazolium iodide (MPII) ionic liquid and iodine for dye-sensitized solar cells (DSSC) application. Polymer electrolytes containing 50 wt.% of both PAN and P(VP-co-VAc) with iodide/triiodide redox mediator (50:50PP-IL) has achieved maximum ionic conductivity, short-circuit (JSC) current and power conversion efficiency (PCE, η) of 6.10 ×10−3 S cm−1, 11.1 mA cm−1 and 5.35%, respectively.

Feasibility study of microplastic biodegradation in effluents from South Tehran WWTP after quantitative and qualitative measurement of the particles

Microplastics are currently known to be among the most detrimental environmental. The research on ways to counteract these pollutions and the use of microorganisms for the biological decomposition of various plastic polymers have evolved over the recent years. In this regard, the present study collected effluents from the southern Tehran treatment plant and separated and counted the microplastics present in them, it was found that the least number of microplastics was found in the samples of the summer season and the highest number of microplastics was found in the samples of the spring season. In these samples, particles could be identified in three forms: fiber, fragment, and film, which revealed that the most frequently observed microplastics were polypropylene and then polyethylene. These microplastics combine with the microbes in the culture medium. Three microbial colonies that survived were then separated and identified, which revealed that these bacteria included Achromobacter denitrificans (sample B), Bacillus amyloliquefaciens (sample C), and Pseudomonas aestusnigri (sample E). Moreover, the decomposition of polypropylene and polyethylene microplastics exposed to isolates was examined through various methods. Results of cellular gravity examination indicated that the average weight reduction in the PP sample exposed to B and E bacterial isolates was 38.2% and 58.9%, respectively. In the SEM images, the surface of the polymers of these two isolates is more uneven. Moreover, the mean cellular weight reduction for PE-based microplastic exposed to isolate C was 13.3%, the results of FT-IR tests showed that the peaks in the samples exposed to strains B and E were accompanied by changes compared to the control sample (G). The results of the TGA test also confirm the greater effectiveness of the bacterial strain E. It was based on the polymer structure. In the Raman spectrum of sample E, some peaks have been removed and new peaks with other shifts have appeared in their place. Results were confirmed by carbon dioxide emission tests and the produced protein amount.

Revisiting the thermal ageing on the metallised polypropylene film capacitor: from device to dielectric film

AbstractMetallised polypropylene film capacitors (MPPFCs) are widely used in power electronics and are generally degraded by elevated temperatures. This work aims to determine the relationships between the structural changes of MPPFC and the microstructural variations of the PP film during the thermal ageing of MPPFC at 100°C for 38 days. The capacitance of MPPFC has a slight decrease during thermal ageing. However, the breakdown voltage of the MPPFC decreases by 39.4% by the ageing. The partial discharge (PD) number of MPPFC increases linearly with ageing time. The tear‐down analysis of the MPPFC reveals that the molecular structure of the PP film has not been altered but has led to molecular chain scission and the generation of some polar fragments/groups. Meanwhile, the relative permittivity of the PP films rises as the ageing time increases. Moreover, thermal ageing causes the conversion of aluminum to alumina in the metallised electrode, which is hydrophilic for polar groups and leads to an adhesion effect between the metallised electrodes and the PP film. Contact angle measurements prove that the surface hydrophilicity of the PP sample increased after thermal ageing. Therefore, the PD/breakdown voltage in the MPPFC increases/decreases due to the uneven adhesion of the metallised PP film.

Technology-enhanced in vivo exposures in Prolonged Exposure for PTSD: A pilot randomized controlled trial

In vivo exposures (IVEs) are a key component of exposure-based treatments, during which patients approach fear-provoking, yet safe, situations in “real life.” This pilot study assessed the use of a wearable technology (Bio Ware) during IVEs to enhance Prolonged Exposure (PE) therapy for PTSD. Bio Ware provides a clinician dashboard with real-time physiological and subjective data for clinicians to use for virtually guided IVEs. Participants (N = 40) were randomized to a Guided group that received standard PE and virtual, clinician-guided IVEs with the Bio Ware device, or a Non-Guided group that received standard PE and used the Bio Ware device on their own for IVEs. Multilevel linear models with bootstrapping were completed on the intent-to-treat (ITT; N = 39) and per-protocol samples (PP; n = 23), defined as completing at least eight sessions of PE and using the Bio Ware system during ≥ 1 IVEs. In the PP sample, there were significant effects of treatment condition (b = −14.55, SE = 1.47, 95% CI [-17.58, −11.78], p < .001) and time (b = −1.98, SE = 0.25, 95% CI [-2.47, −1.48], p < .001). While both groups showed reductions in PTSD symptoms, the Guided group evidenced significantly greater reductions than the Non-Guided group. These findings demonstrate the feasibility and safety of leveraging Bio Ware for virtual, clinician-guided IVEs during PE therapy for PTSD and suggest that virtual, clinician-guided exposures may enhance treatment outcomes. Clinical trial registrationNCT04471207.

Physicochemical, structural and functional properties of pomelo spongy tissue pectin modified by different green physical methods: A comparison

Pectin is a valuable bioactive ingredient, but its practical application is limited in many areas due to its high molecular weight and complex structure. In this work, the effect of different physical methods (ultra-high pressure, ultrasonic, and high-temperature cooking) on the physicochemical, structural, and functional characteristics of pomelo spongy tissue pectin (PP) were investigated. Ultra-high pressure treatment (300 MPa, 15 min) decreased the degree of esterification (DE, 4.53 %) and the degree of acetylation (DA, 2.76 %) of PP. And the PP subjected to the ultrasonic treatment (200 W, 20 min) exhibited the highest esterification degree (66.02 %), galacturonic acid content (GalA, 406.40 mg/g), and degradation enthalpy (66.93 J/g). Meanwhile, the PP treated with high-temperature cooking (HCT, 120 °C, 30 min) had the lowest acetylation degree (2.02 %), molecular weight (8.48 × 104 Da), and GalA content (254.92 mg/g). SEM and XRD results showed that the degradation effect of high temperatures on PP was more evident than other physical modification methods. Remarkably, all modified pectin solutions showed lower viscosity compared to untreated PP solution. Among these PP samples, higher antioxidant activity (103.29–134.22 mmol TE/g FRAP and 646.27–705.25 mmol TE/g ORAC values) was found in the HCT-treated PP. Moreover, the ultra-high pressure and ultrasound modified pectins revealed better emulsifying activity and emulsifying stability than unmodified PP. The results of this study indicated that the PP could be treated to achieve the desired functional application through these three physical modification methods.

Surface modification of poly(propylene) fabric with graphene oxide‐based silver nanoparticles for antibacterial applications

AbstractHerein, poly(propylene) (PP) was hydrophilized with oxidating agents and solvents, followed by dip‐coating with silver nanoparticles anchored GO sheets (Ag@GO) prepared by the in‐situ method as reported in our previous study to obtain silver@graphene oxide‐coated poly(propylene) (Ag@GO/PP). The impact of the modifying agents, dipping times, and coating concentrations on the antibacterial activities were studied accordingly via the inhibition zone method. The fabrics were re‐hydrophobized with the reduction of Ag@GO and the functionalization with stearic acid (SA) to form silver@reduced graphene oxide‐coated poly(propylene) (Ag@rGO/PP) and silver@graphene oxide/SA‐coated poly(propylene) (Ag@rGO‐SA/PP), respectively. Characterization of pretreated and modified PP samples was carried out by various modern analysis methods. Simultaneously, the cytotoxicity of the active layers, the release of Ag+ ions, and durability after washing were also investigated. The obtained results representing PP fabrics pretreated with HNO3/isopropanol and dipped in Ag@GO concentration of 2 g/L four times prove a sufficient approach for improving hydrophilization and bio‐compatibility for the PP samples. The fabrics greatly show an impressive interaction with precursors, mostly high antibacterial activity even after four washing cycles via appropriate releasing of Ag+ to ensure the safety in usage. They further suggest that the prepared fabrics could be utilized for actual application as a face mask.

Ultrahigh Low-Temperature Toughness of Polypropylene Composites with Low Ductile-Brittle Transition Temperature by Introducing Traces of Needlelike Wollastonite

In order to survive harsh settings, such as outer space, deep sea and high plains, needlelike wollastonite fibers (WF) were incorporated into polypropylene/ethylene octene block copolymer/β-nucleating agent (PP/OBC/β-NA) blends with the hope of tailoring the low-temperature toughness. The results revealed that WF showed very satisfactory toughening effects in the PP/OBC/β-NA/WF composites at low temperature (–20 °C). The impact strength of the WF-0.05 was as high as 32.1 kJ/m2 at −20 °C, which was 286.6% higher than that of the WF-0 sample, and even 832.6% higher than that of the pure PP sample. SEM characterization showed that by simultaneously adding WF and β-NAs, much coarse and tremendous plastic deformation appeared in the WF-0.05 after impacting. The low-temperature toughening mechanism is systematically discussed. The increase of β-crystallinity, caused by the synergy of β-nucleating agent and WF fillers, was mainly responsible for the enhancement of the impact strength of the composites with WF. On the other hand, when the transmitting of the stress, the overlapping of the stress and the hindering effect of WF on cracks occurred simultaneously; it resulted in the excellent low temperature toughness of the PP composites. Such outstanding-performance material with the advantages of facile processing and low cost is unprecedented. It shows a promising future application in many fields, especially aerospace, navigation, and the automotive industry.

Effects of Different Concentrations of Arsine on the Synthesis and Final Properties of Polypropylene.

This article studies the effects of arsine on the synthesis and thermal degradation of 4 samples of virgin polypropylene (PP-virgin) and proposes reaction mechanisms that allow understanding of its behaviour. Different points are monitored during the polypropylene synthesis to perform TGA, DSC, FT-IR, RDX, and MFI analyses later. The content of AsH3 in polypropylene varies between 0.05 and 4.73 ppm, and of arsenic in virgin PP residues between 0.001 and 4.32 ppm for PP0 and PP10, increasing in fluidity index from 3.0 to 24.51. The origin of thermo-oxidative degradation is explained by the reaction mechanisms of the Molecule AsH3 with the active titanium center of the ZN catalyst and the subsequent oxidation to form radical complexes. OO-AsH-TiCl4-MgCl2 and (OO-as-OO)2 -TiCl4-MgCl2, which, by radical reactions, give rise to the formation of functional groups aldehyde, ketone, alcohol, carboxylic acid, CO, CO2, PP-Polyol, PP-Polyether, and PP-Isopropylethers. These species caused the TG and DTG curves to increase degradation peaks in pp samples.

Eco-friendly stabilization of highway lateritic soil with cow bone powder admixed lime and plastic granules reinforcement

Modernization, industrialization and rapid changes in the modern lifestyle have resulted in massive waste materials in the environment. Scientists are continuously evolving innovative ways for efficient reuse/recycling and the safe disposal of waste materials. This study explores potential waste materials reuse in additive stabilization of a fair to poor highway lateritic soil (clay with low plasticity/silty clay) as a sub-base material and the impact of such additives in reducing the lime content during soil stabilization treatment. Soil samples obtained from road construction burrow pit in Ado-Ekiti, south-west, Nigeria were classified as CL group (clay with low plasticity), according to the Unified Soil Classification System (USCS) and A-6 material (silty clay) which is fairly poor highway material. Hydrated lime, Cow bone and plastic wastes were also locally sourced. Geotechnical tests (Compaction, Unconfined Compressive Strength test, direct shear and consolidation test) were carried out on the control and stabilized samples according to BS 1990. The results of the Unconfined Compressive Strength tests revealed that the 90 % lateritic soil +10 % lime and a combination of 6 % lime +7 % cow bone powder +1 % plastic waste (6 % L +7 % CBP + 1.0 %PP) mixes produced the best result for the lime stabilized and waste-lime stabilized soil samples, respectively. The direct shear tests, indicated a reduction in the soil’s cohesion (c) from 38 kN/m 2 to 28 kN/m 2 and an improvement in the angle of internal friction ( ϕ ) from 29º to 45º for the optimum waste-lime mix. 10 % lime (L 10 ) sample recorded comparatively lower c and ϕ values of 33 kN/m 2 and 41º, respectively. The mix (6 % L +7 % CBP + 1.0 % PP) had improved the unsoaked and soaked CBR of 61.7 % and 37.6 %, respectively compared to the lime stabilized soil which recorded lower values of 57.8 % and 31.3 %, respectively. The permeability of the soil was reduced from 3.22e-03 cm/s to 9.12e-04 cm/s on the application of 10 % lime however the waste-lime optimal mix produced a lower value of 5.26e-04 cm/s. The results of the consolidation tests also revealed that the 6 % L +7 % CBP +1.0 % PP sample had a lower coefficient of volume compressibility (Mv) of 1.065e-04 m 2 /kN than the untreated samples which is 1.365e-04 m 2 /kN implying the stabilized mix is less susceptible to compressibility than the untreated samples. The durability results revealed that the sample recorded a strength of 201.7 kPa after being subjected to 3 wet-dry (w-d) cycles for 6 % L +7 % CBP +1.0 % PP sample, while the 10 % lime stabilized soil was found to have a strength of 148.5 kPa strength. Based on the findings, it can be concluded that the 6 % L +7 % CBP +1.0 % PP mix performed better than the 10 % lime stabilized mix with the waste materials substituting for 4 % of the lime and producing better results in terms of suitability as a highway sub-base material. • The partial replacement of lime improved weak highway lateritic soils. • Waste materials (cow bone powder and plastic granules) were suitably reused. • Near-zero emissions processing of stabilization additives was achieved. • Cleaner and energy-saving methods were employed for the disposal of waste. • Reduced weather sensitivity and compressibility were achieved for the soil mixture.

An energy‐based approach to study the aggregation/agglomeration phenomenon in polymer nanocomposites: Dispersion force against inter‐particle cohesion

AbstractIn this study, a novel method was proposed to predict the size and content of the nanoparticle aggregates/agglomerates in polymer nanocomposites based on the characteristics of the mixer, cohesion energy between nanoparticles and their content in the system. The internal energy equilibrium was evaluated by calculating the induced mixing energy by the mixer, aggregation, and agglomeration energies. An analytical model was designed to predict the tensile modulus of the system based on dispersion content and size of the aggregates/agglomerates. In addition, the tensile modulus of the aggregates/agglomerates was defined by developing Wacke's empirical equation. Two sets of PP and PA6 nanocomposite samples, containing 1–3 vol% of silica nanoparticles, were prepared and tested to verify the theoretical results. The applied nanoparticles were subjected to surface modification processes to maximize their compatibility with their surrounding polymer matrix. Different tests, including FE‐SEM, contact‐angle and tensile, were used to determine the mechanical/physical characteristics of the samples. The predicted results for the size of the aggregated/agglomerated domains were very close to those defined using FE‐SEM tests. On the other hand, the predicted tensile moduli based on the content, size and mechanical characteristics of the aggregated/agglomerated domains were acceptably accurate considering the tensile test results.

The effects of weathering-induced degradation of polymers in the microplastic study involving reduction of organic matter

The analysis of microplastics in complex environmental samples requires the use of chemicals to reduce the organic matrix. This procedure should be evaluated in terms of the preservation of the microplastic's integrity, typically done with pristine reference microplastics. However, real microplastics are most likely degraded due to weathering, so pristine reference microplastics might not depict the appropriateness of the process. This study performed a purification process using sodium dodecyl sulfate and hydrogen peroxide on sewage sludge containing LLDPE, HDPE, PP, PS, PET, PA66 and SBR samples exposed to simulated environmental weathering. The degradation of the polymers was assessed by analyzing surface morphology, mass variation, and mechanical, thermal and chemical properties. Comparison with pristine polymers revealed that the purification process can lead to more detrimental effects if the polymers are weathered. After the purification process, some important observations were: 1) LLDPE, PP and SBR surfaces had cracks in the weathered samples that were not observed in the pristine samples, 2) weathered LLDPE, PP and PA66 experienced greater mass loss than pristine, 3) the fragmentation propensity of weathered LLDPE, HDPE, PP, PS and SBR increased compared to pristine samples and 4) the main characteristic peaks in FTIR spectrum could be identified and used for chemical identification of most polymers for pristine and weathered samples. Based on the findings of this study, when analyzing the efficiency and adequacy of a purification process with methods based on surface morphology, mass variation and particle counting indicators, it is recommended to consider the differences that potentially arise between pristine and weathered microplastics, especially for polyolefins (PEs and PP).

Morphology and crystallization kinetics of G‐resins and isotactic polypropylene

AbstractIsothermal crystallization and morphology of G‐resin (GPP) and isotactic polypropylene (iPP) samples were investigated and compared using synchrotron small‐ and wide‐angle X‐ray scattering/diffraction (SAXS/WAXD) and differential scanning calorimetry (DSC). Two GPP resins (MT12‐s and MT18‐s) are iPP containing a small amount of 1‐butene. All polymers have similar MW and PDI, denoted by V30G, MT12‐s, and MT18‐s with 1‐butene = 0.00, 6.43, and 5.20 wt%, respectively. DSC isothermal crystallization at 130°C showed that the crystallinity of G resins were lower, but the crystallization rate of G resins was faster in the order as MT18‐s ≥ MT12‐s &gt; V30G. Simultaneous synchrotron SAXS/WAXD was employed to determine polymer morphology crystallized from the melt. The electron density correlation function was calculated to estimate the lamellar thickness. The long periods (D) are around 19.0, 25.8, and 25.8 nm for V30G, MT12‐s, and MT18‐s, respectively. The GPP samples have a larger amorphous portion and a higher crystalline thickness (L) but a lower L/D ratio than IPP. The degree of crystallinity by WAXD is also smaller for GPP, that is, MT18‐s (31%) ≈ MT12‐s (31%) &lt; V30G (&gt;50%). In addition to the monoclinic α forms for all the PP samples, the orthorhombic γ forms were found only for MT12‐s and MT18‐s. The crystallization of G‐resins should be nucleated from the transparent filler and are not fully an intrinsic property of the copolymer chains.

Optical and electromagnetic absorption features of hierarchical pampon and cauliflower-like magneto/dielectric composite based absorber for C and X bands application

Hydrothermal and in-situ polymerization methods were used to successfully fabricate a pompon flower-like CoGd0.5Fe1.5O4 (CG) as a magnetic component and a cauliflower-like poly(indole-co-Py) (PP) co-polymer as a dielectric component for microwave absorption. The physico-chemical properties of CG/PP samples were determined via XPS, XRD, FTIR, BET, UV–vis, EDS, and FESEM analysis. VNA and VSM were used to evaluate the dielectric and electromagnetic properties of the CG and PP samples. The results of the absorption capability tests revealed that bi-layer samples outperformed single layer samples in terms of microwave dissipation capability. The thickness and arrangement of each layer in bilayer absorber effectively adjusted via MATLAB simulation. As a consequence, the effective absorption bandwidth in the bilayer absorber has been increased and covers the C and X bands entirely with a thickness of only 2 mm, in which 1 mm of CG composite layer with 1 mm of thickness is placed as an absorbing layer and a PP composite layer with 1 mm of thickness is considered as a matching layer. The hierarchical structure of both components (pompon and cauliflower-like morphology) may increase interfacial polarization, relaxation loss, and consequently attenuation constant of the absorber as well as improve impedance matching characteristics and decrease in density. Synergistic effects between two distinct layers containing magnetic and dielectric components may further increase the absorption feature.