Polypropylene Materials Research Articles

A comprehensive summary on the enhancement of properties of concrete with recycled polypropylene materials

AbstractThe scientific community is currently confronted with critical problems in providing a healthy world for future generations. The study for sustainable plastic recycling methods is difficult for a variety of purposes. Indeed, during the previous century, the widespread usage of plastic materials has resulted in vast amounts of long‐lasting waste that has remained largely unaddressed by effective collection and disposal policies. Packaging materials are responsible for the majority of this waste which also includes polypropylene materials. However, environmental concerns imposed a new trend in the previous decade that brought this research under focus, as seen by the growing number of linked publications. For the recycling of polymeric plastic materials, several chemical and mechanical methodologies have been proposed. Due to the low ultimate tensile strain of concrete, plastic waste fiber materials have been used in concrete in recent times as the reinforced concrete components often function with cracks during the serviceability phase. The bonding strength and stress variation during flexure, toughening effect of a hybrid combination of steel and recycled polypropylene fibers on high‐strength concrete are investigated. Polypropylene's compressive and tensile strength, good dielectric characteristics, and acid and alkali resistance have all been observed in various studies. Hence the current review focus on the past researches on utilization of recycled polypropylene in concrete for the enhancement of its physical and mechanical properties.

Effect of silver particles on the crystal structure and the mechanical, optical and antibacterial properties of various polypropylene based plastomers and elastomers

In composite materials consisting of silver particles and a polypropylene matrix, the silver must migrate to the surface of the materials in order to exert on antibacterial effect. Substrates with various crystal structures may have different interactions with the silver particles, which can significantly impact the antibacterial performance. The research described in this paper investigates the influence of silver particles on the crystallization behavior of materials with varying crystallinity capabilities by selecting various polypropylene-based plastics and elastomers (Homopolymer polypropylene (PPH-T03), random poly(propylene/ethylene) copolymers (PPR-YPR503 and PPR-P340R), polyolefin elastomers (VERSIFY3000 (POE-1) and VERSIFY3401 (POE-2)), and ethylene propylene diene monomer for polymers (EPDM4725 and EPDM4770)). The research results indicated that the silver only entered the amorphous regions of the PP rather than entering the crystal regions, where they can more easily migrate to the material surface, resulting in a higher antibacterial effect. Therefore, the antibacterial degree of PP-Ag was as high as 99.9%. Silver can enter the micro-crystals of both the random copolymer polypropylene, (PPR-YPR503, PPR-1) and the random copolymer polypropylene, (PPR-P340R, PPR-2,) with a stronger effect on PPR-2. More silver entered the micro-crystals of PPR-2, and it was difficult for the silver ions to migrate out of the crystalline regions to exhibit antibacterial properties. The antibacterial degree of PPR-1-Ag was higher than that of PPR-2-Ag (77.8% vs. 66.7%). Similarly, silver had a greater impact on the lamellar structure of the polyolefin elastomer (VERSIFY3401, POE-2) compared to the polyolefin elastomer (VERSIFY3000, POE-1). In comparison with POE-2-Ag, POE-1-Ag exhibited a higher antibacterial degree (79.6% vs. 57.4%). Research on the two types of ethylene propylene diene monomer (EPDM) composite materials indicated that EPDM-1 exhibited a lower Mooney viscosity and poorer flowability. The EPDM-1 tended to encapsulate the silver within its molecular chains, thereby impeding the migration of silver to the surface. The optical performance analysis indicated that silver antibacterial agents had little impact on the optical properties of PP-Ag, PPR-1, PPR-2, POE-1, POE-2 and the EPDMs. We suggest that this research provides theoretical guidance for selecting highly antibacterial polypropylene materials.

Biopolymer-loaded plasma-mediated multi-functional finishes of polypropylene fabrics

Polypropylene (PP) has unique competitiveness with other synthetic fibers due to its suitable spinnability, availability of raw materials, and low processing cost. PP fabric exhibits excellent chemical, physical, and mechanical properties, such as a light texture, adequate tensile strength, and resistance to most chemicals. However, the absence of reactive functional groups in PP fiber, besides its high crystallinity, results in hydrophobic surface, low affinity to dyestuffs, and poor antistatic properties, which restrict its use in the clothing field. Herein, a water- and energy-saving, eco-friendly finish is proposed to render PP desired properties suitable for textile applications. The surface of PP fabric was activated using oxygen and nitrogen plasma radiations. The plasma-irradiated PP fabric was post-treated with two renewable eco-friendly proteinic biopolymers, namely gelatin and sericin, in the presence and absence of a crosslinking agent. The effects of different process conditions on the properties of the modified PP, including the duration of plasma exposure, the concentration of biopolymer, and treatment temperature were monitored. The affinity of the treated PP fabric towards anionic and cationic dyes was evaluated. The findings of this study demonstrated that the comfort attributes of the plasma/biopolymer-finished fabrics, such as the induced antistatic properties, wettability, and ultraviolet protection, were remarkably improved. The plasma-mediated biopolymer-finished PP fabrics were found dyeable with cationic and anionic dyes. The change in the chemical and morphological structures of PP fabrics was monitored using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy.

Mechanical properties of eco-friendly self-compacting concrete made from partially replaced single-use waste plastic and complete recycled coarse aggregate using RSM and ANN methods

The paper aims to use most of the recycled material from the waste and develop a sustainable Eco-Friendly Self-Compacting Concrete (EF-SCC). Two different plastic wastes, High-Density Polyethylene (HDPE) and Polypropylene (PP), were collected from the dumping yard, thoroughly cleaned, and shredded into the desired shape and size. The plastic was substituted with fine aggregate (FA) in amounts ranging from 5% to 20%, with a 5% rise in each mix. The recycled coarse aggregate was obtained by breaking the concrete cubes, beams, and cylinders available for testing at the concrete technology lab. Totally 4 mixes were prepared for M40 grade EF-SCC to determine the mechanical property at 4 different ages (7, 14, 28 and 56 days). The compressive strength results were then predicted using statistical tools such as RSM and ANN. It is observed that both HDPE and PP have workability in the range of 650mm to 800mm, which is acceptable according to EFNARC 2002. The RSM method yielded 99.69% for PP material, while HDPE had 98.17%. The optimum compressive strength values were achieved at 7.5% of HDPE and 5% of PP material at 28 days and 60 days of curing. The training, validation, Test, and All values of R for M40 grade concrete for HDPE and PP material were 0.9955, 0.9980, 0.9244, 0.9241, and 1, 0.972, 0.802, 0.972 respectively. The flexural strength of EF-SCC showed the best results at 15% replacement. The prediction of actual compressive strength with RSM was more accurate for HDPE material compared to ANN. Recycled aggregate showed positive signs in using waste material in construction industries.

Properties of chemically foamed polypropylene materials for application to automobile interior door panels

Abstract In recent years, alternative approaches have been implemented in the automotive sector to reduce raw material costs and protect the environment. An increase in weight causes both fuel consumption and CO2 emissions to rise. This study aims to reduce exhaust emissions due to weight reduction by using foamed polypropylene in the door panel production of a subcompact crossover SUV car and saving energy by shortening the injection cycle time. The newly produced 2 % ITP 822 chemical foaming agent added door panel was compared with the current door panel performances. As a result of foam morphology structure, impact, and hardness tests, it was decided that ITP 822 is a suitable chemical foaming agent. In addition, a weight reduction of 5.2 % was achieved. Moreover, the injection cycle time has been reduced by approximately 12 %, reducing the total cycle time from 35 s to 31 s.

Experimental Thermal Conductivity Measurement of Hollow-Structured Polypropylene Material by DTC-25 and Hot Box Test

In this study, experimental measurements of porous polypropylene (PP) using the DTC-25 TA laboratory equipment and a hot box test are compared. The thermal conductivity of building materials indicates their insulation capability. Excellent building materials will have a lower thermal conductivity value as well as other building insulator performance metrics. While results show that increasing the volume fraction of fluid in porous PP has an inverse association with the thermal conductivity of the material, as predicted by porous media theories, there is a marked difference in the measured values of thermal conductivity using the two methods. The thermal conductivity values of porous PP from the DTC-25 and the hot box test were 0.21 and 0.0033 W/mK, respectively. The difference in the thermal conductivity values was due to the misapplication of the Fourier’s guarded heat flow model in the DTC-25 device to a convective fluid porous medium.

Antimicrobial activity of silver-copper coating against aerosols containing surrogate respiratory viruses and bacteria

The transmission of bacteria and respiratory viruses through expelled saliva microdroplets and aerosols is a significant concern for healthcare workers, further highlighted during the SARS-CoV-2 pandemic. To address this issue, the development of nanomaterials with antimicrobial properties for use as nanolayers in respiratory protection equipment, such as facemasks or respirators, has emerged as a potential solution. In this study, a silver and copper nanolayer called SakCu® was deposited on one side of a spun-bond polypropylene fabric using the magnetron sputtering technique. The antibacterial and antiviral activity of the AgCu nanolayer was evaluated against droplets falling on the material and aerosols passing through it. The effectiveness of the nanolayer was assessed by measuring viral loads of the enveloped virus SARS-CoV-2 and viability assays using respiratory surrogate viruses, including PaMx54, PaMx60, PaMx61 (ssRNA, Leviviridae), and PhiX174 (ssDNA, Microviridae) as representatives of non-enveloped viruses. Colony forming unit (CFU) determination was employed to evaluate the survival of aerobic and anaerobic bacteria. The results demonstrated a nearly exponential reduction in SARS-CoV-2 viral load, achieving complete viral load reduction after 24 hours of contact incubation with the AgCu nanolayer. Viability assays with the surrogate viruses showed a significant reduction in viral replication between 2–4 hours after contact. The simulated viral filtration system demonstrated inhibition of viral replication ranging from 39% to 64%. The viability assays with PhiX174 exhibited a 2-log reduction in viral replication after 24 hours of contact and a 16.31% inhibition in viral filtration assays. Bacterial growth inhibition varied depending on the species, with reductions ranging from 70% to 92% for aerobic bacteria and over 90% for anaerobic strains. In conclusion, the AgCu nanolayer displayed high bactericidal and antiviral activity in contact and aerosol conditions. Therefore, it holds the potential for incorporation into personal protective equipment to effectively reduce and prevent the transmission of aerosol-borne pathogenic bacteria and respiratory viruses.

The Use of Polymeric Materials of Polyethylene Terephthalate (PET) and Polypropylene (PP) as the media of Anaerobic-aerobic bioreactors in treating wastewater from the tofu industry

Small-scale businesses often dominate the tofu sector in Makassar City, preventing any prior wastewater management. While tofu is typically produced on a household scale, the wastewater treatment process is limited due to the need for suitable technology and high prices. Therefore, it is necessary to conduct this research to obtain tofu wastewater results that meet environmental discharge standards and develop a straightforward and affordable waste treatment concept. A laboratory scale with an experimental method is used in this study, where the test parameters used were BOD, COD, and TSS using two types of biofilter media, namely mineral water bottle media made of PET plastic and plastic straw media made of PP plastic with variations in observation time of 24 hours for six days. The results presented that the efficiency of the average removal in plastic-media reactors with mineral water bottles reduced BOD by 88.30%, COD by 88.97%, and TSS by 79.13%. The straw-based plastic reactor reduced BOD by 86.74%, COD by 85.41%, and TSS by 67.03%. The effectiveness value obtained shows that biofilter media made from plastic mineral bottles (PET) produces better effectiveness in removing BOD, COD, and TSS than biofilter media made from plastic straws (PP).

Long-lasting anti-bacterial face masks enabled by combining anti-bacterial materials and superhydrophobic coating

Face masks are widely used for protecting against the COVID-19 pandemic and other diseases. However, the lack of virucidal properties in conventional face masks increases the risk of cross-infection and potential contamination. Here, we report preparation of a superhydrophobic and anti-bacterial polypropylene fabric by in turn incorporation of ZnO nanoparticles and perfluorodecyl polysiloxane modified SiO2 nanoparticles. The fabric exhibits high superhydrophobicity with a water shedding angle of ~6° and excellent moisture resistance, which enable maintenance of functionality effectiveness of the face masks in cold weather conditions. When utilized as a middle layer in face masks, the fabric demonstrates remarkable anti-bacterial activity against E. coli in both laboratory and outdoor environments. This anti-bacterial performance is attributed to the synergistic effect of superhydrophobicity and the ZnO nanoparticles. The excellent superhydrophobicity significantly reduces adhesion of E. coli on the fabric. Meanwhile, the embedded ZnO nanoparticles can eliminate the small number of adhered bacteria through their inherent anti-bacterial property. The combination of superhydrophobicity and anti-bacterial property in the fabric presents a promising solution for enhancing the performance of face masks. The superhydrophobic anti-bacterial fabric holds great potential for various practical applications in the field of personal protective equipment, healthcare, and disease prevention.

Green Physical Modification of Polypropylene Fabrics by Cross-Linking Chitosan with Tannic Acid and Postmodification by Quaternary Ammonium Grafting to Improve Antibacterial Activity.

A green cross-linking and straightforward method to physically trap inert fibers in a network of chitosan was implemented. The cross-linking reaction involved a biosourced and biocompatible cross-linker [tannic acid (TA)] and mild conditions in water (pH = 8.5, O2 bubbling, 60 °C, 3 h). The steric hindrance of TA led to a low but effective cross-linking rate leaving parts of primary amines of chitosan available for postmodification such as the grafting of quaternary ammoniums for antibacterial purposes. Fabric's coatings were characterized by scanning electron microscopy coupled with energy-dispersive X-ray, infrared spectroscopy, and weight gain measurements. This allowed the optimization of process conditions. No significant antioxidant activity was observed on fabrics coated with chitosan cross-linked with TA, confirming the low cross-linking rate. This low cross-linking rate allowed grafting of quaternary ammoniums for antibacterial purposes, but it is possible to consider grafting other active molecules. Biological assays were conducted on this coating to assess its antibacterial properties. Reduction of bacterial colonization on both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), two of the major strains responsible for nosocomial infections, confirmed the potential of the coating for antibacterial purposes. This study displays a simple and ecofriendly process to coat inert fabrics with a chitosan network containing reactive functions (primary amines) available for grafting active molecules for various purposes.

Field Study of Activity of Antimicrobial Polypropylene Textiles

In this work, an in situ study is presented of the impact of textile materials used in healthcare facilities on microbial colonization of textile surfaces. The available literature describes antimicrobial active textiles and their effectiveness in laboratory conditions. However, the quantification of the impact on the microbiome of healthcare facilities has not been investigated so far. Polypropylene yarns doped with silver phosphate glass and zinc pyrithione were prepared and used for the production of bed sheets and clothing for healthcare personnel. Subsequently, measurements of airborne particles and viable microorganisms on given textiles were conducted in a private surgery clinic for 3 weeks, comparing the counts of viable microorganisms before and after replacing staff clothing and bedding on examination and the surgical bed with said polypropylene cloth. A significant reduction in airborne particles and viable microorganisms was expected based on previous studies on the use of polypropylene textiles in operating rooms. In this study, a significant reduction in viable airborne fungi and viable microorganisms on monitored textiles was observed by multiple methods. However, the effect on airborne microorganisms seems insignificant in areas with frequent patient traffic. The textile described here represents a new additional way of protecting patients and medical personnel from healthcare-associated infections while using a modification of proven production procedures and commercially usable materials without legislative restrictions.

Electrical-Tree Resistant Characteristics of SEBS and Nano-SiO2 Modified Polypropylene Composites

Polypropylene (PP) composite materials with both high mechanical toughness and electrical insulation performance are prepared by incorporating styrene-ethylene/butylene-styrene (SEBS) block copolymer as a toughening agent and nanoscale silica (SiO2) as a inorganic modifier to enhance electrical-tree and breakdown resistances. The effects and mechanisms of SEBS toughening agent and SiO2 nanofiller on the thermal-mechanical properties and electrical insulation performances of PP material are investigated through the mechanical tests as well as the accelerated electrical-tree aging and alternative current (AC) breakdown experiments. The elastic modulus of SiO2/SEBS/PP composite is slightly lower than that of pure PP material, while the thermal elongation rate remains superior to cross-linked polyethylene (XLPE), which is competent in mechanical performances for main insulation materials in high-voltage cables. The addition of styrene-ethylene/butylene-styrene (SEBS) facilitates electrical-tree growth in PP matrix and thus leads to the reduction in dielectric breakdown strength of PP material. In contrast, the incorporation of nano-SiO2 can effectively improve the electrical-tree resistance and dielectric breakdown strength of PP material, making the SiO2/SEBS/PP composite a promising candidate for high-voltage cable insulation. The tests and analyses of thermal stimulated depolarization current (TSDC) reveal that the SEBS toughing additive introduces the shallow charge traps in PP matrix, making it easier for the trapped charges to transition into charge carriers, thus leading to a considerable decrease in electrical-tree resistance and insulation strength of PP material. Meanwhile, the SiO2 nanofiller can introduce deeper charge traps into PP matrix than the structural-defect intrinsic charge traps, resulting in a significant amelioration in the electrical-tree resistant and insulation performances for SEBS/PP composite. The present study demonstrates that SiO2/SEBS/PP composite possesses sufficiently high electrical-tree resistance and dielectric breakdown strength as well as suitable thermal-mechanical properties, offering a potential application in main insulation of high-voltage cables and providing an effective pathway for developing novel recyclable AC high-voltage cables.

Low-temperature micromechanical properties of polyolephin/graphene oxide nanocomposites with low weight percent filler

The effect of small impurities of reduced graphene oxide (rGO) on microhardness of polyethylene (PЕ) and polypropylene (PP) matrices and the reaction of these nanocomposites and initial polymers on the influence of localized load in the temperature range of 77–295 K were studied. When rGO was introduced, PE practically did not change its properties, whereas the introduction of 0.3 wt% rGO into the PP matrix was accompanied by a significant increase in microhardness, especially in the room temperature range (by approximately 70%). A transition to reversible deformation was detected when the indenter impressions applied in liquid and gaseous nitrogen at temperatures below the threshold (T < 174.5 K for PP and T < 226.5 K for nanocomposite PP + 0.3 wt% rGO) were not fixed on the surface of the samples after their heating in the measuring device to room temperature.

Types of Polymers Using in 3D Printing and Their Applications: A Brief Review

The technology based on using 3D printing machines (3DPs) can be considered a promising approach in industry. A 3D printer might be define as machines which manufacture 3D products or models that already designed by computer aided design (CAD) software programs. These machines can create geometries that are very complicated and so difficult to fabricate by traditional manufacturing approaches. Additionally, it has capability to create items that is so complex internal design products with lower time and cost. Several kinds of materials have been applied in this technology. The polymers is one the most common materials that are using in 3D printing. This review seeks to clarify the features and benefits of different types of polymers including Acrylonitrile Butadiene Styrene (ABS), Polylactic acid (PLA), Acrylonitrile styrene acrylate (ASA), Polyethylene terephthalate (PET), Glycolized polyester(PETG), Polycarbonate (PC), Polypropylene (PP), Nylon, and Hybrid and composite materials.

Functional separator with 1 T/2H-MoSe2 nanosheets decorated nitrogen and sulfur co-doped mesoporous hollow carbon spheres for high-performance Li-S batteries

Due to the dissolution, shuttling, and tardy kinetics conversion of lithium polysulfides (LiPSs) during cycling, there are serious defects in the utilization of active material and capacity retention ability for lithium-sulfur batteries (LSBs). To inhibit effectively the shuttling effect of LiPSs, herein, we propose the dual design strategies, using 1 T/2H mixed phase MoSe2 (1 T/2H-MoSe2) nanosheets uniformly growing on the external surface and inner wall of nitrogen and sulfur co-doped mesoporous hollow carbon spheres (MoSe2-NSHC) as both sulfur host and modified material of conventional polypropylene (PP) separator. The hollow structure of MoSe2-NSHC has a large specific surface area and internal space, which not only loads a large amount of sulfur, but also buffers severe volume expansion of sulfur during charge/discharge process. Meanwhile, 1 T/2H-MoSe2 and co-doped nitrogen and sulfur in the carbon skeleton effectively anchor LiPSs and accelerate the kinetics conversion of LiPSs by forming chemical bond. Density-functional theory calculations indicate the corresponding mechanisms. Based on these advantages, lithium-sulfur battery assembled with a MoSe2-NSHC/S cathode and a MoSe2-NSHC-PP separator delivers an initial discharge capacity of 1402 mAh/g at 0.2C, and also exhibits the first discharge capacity of 1155 mAh/g at 0.5C with a capacity retention rate of 79 % after 100 cycles. And after 800 cycles at 1C, the outstanding long-term cyclability with a low capacity decay per cycle of 0.039 % is also obtained. Notably, even in case of sulfur loading of 3.2 mg cm−2 and electrolyte/sulfur ratio of 6 μL mg−1, lithium-sulfur battery still exhibits a good electrochemical performance. Importantly, this work provides a feasible approach for commercial application of LSBs.

Low-cost ZIF-67-modified fabrics with effective photothermal disinfection for antimicrobial personal protective equipment production

Aerosol-based transmission contributes to infection by various pathogens. Consequently, it is urgent to design antimicrobial personal protective equipment (PPE) and address the potential biological contamination of discarded PPE. We report a novel ZIF-67-modified PP fabric for photothermal disinfection; our work provides a fast, one-step, and low-cost preparation approach for incorporating zeolitic imidazolate framework (ZIF) nanoparticles (NPs) onto polypropylene (PP) fabric. First, we prepared ZIF-67-water NPs and ZIF-67-methanol NPs using relevant solvents and characterized them by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and field-emission scanning electron microscopy. We then used only ultrasonication to prepare ZIF-67-modified fabrics by incorporating ZIF-67 NPs onto PP fabric with a 0.5－1.5 mg/cm2 loading rate (18.5－40.5 wt%). The ZIF-67-modified fabrics were subjected to the same characterization, and then they were evaluated for photothermal performance, hydrophobicity and antimicrobial ability. The fabric of ZIF-67-water@PP-1.5 was selected to repurpose an antimicrobial mask. We demonstrated that the ZIF-67-modified fabrics have excellent photothermal performance with near-infrared (NIR) radiation and exhibit increased hydrophobicity, which is determined by the loading rate of ZIF-67 NPs. The surface temperature reached and maintained peak levels (70 °C and 90 °C) with NIR radiation, whilst the highest contact angle was over 140°. The photothermal behaviour could kill over 99.9% of gram-negative and gram-positive drug-resistant bacteria, whilst the haemolytic behaviour was less than 5%. The repurposed mask retained controllable photothermal properties. The application of these fabrics not only addresses the demand for affordable antimicrobial PPE but also contributes to reducing potential biochemical threats in discarded PPE.

Optimizing titanium carbide (TiC) ceramic nanofiller loading in isotactic Polypropylene for MEX additive manufacturing: Mechano-thermal and rheology aspects

Herein, Titanium carbide (TiC) was assessed as a reinforcing additive in the polypropylene (PP) thermoplastic. The thermomechanical and rheological characteristics of the prepared nanocomposites were evaluated. A thorough characterization strategy was designed and implemented (eleven different experiments). The nanocomposites were made using the melt extrusion technique (extruder). For the experiments, samples of the PP/TiC nanocomposites were produced by utilizing the fused filament fabrication (FFF) additive manufacturing (AM) technique. By altering the weight percentage of TiC from 0.0% to 10.0%, the effects of TiC on the characteristics of the composite material were investigated. Scanning electron microscopy (SEM) analyzed the fractography and morphology of the produced specimens, while Raman spectroscopy and energy dispersive spectroscopy (EDS) were employed to identify and assess the chemical structure of the polymer material and respective nanomaterials. Rheological investigations were also conducted. The addition of Titanium carbide nanopowder/nanoparticles greatly improved the mechanical properties of the PP material. The best mechanical performance was achieved by the PP/ TiC 6 wt% compound showing an enhancement of 17.5% and 17.1%, respectively over the flexural and the tensile strength. The results showed these PP-based nanocompounds can achieve optimal results for specific purposes and demanding applications.

Fabrication methodologies for antimicrobial polypropylene surfaces with leachable and nonleachable antimicrobial agents

AbstractReported herein is the fabrication of antimicrobial polypropylene (PP) surfaces with nonleachable magnesium hydroxide biocides and compares its performance with leachable copper (II) chloride dihydrate. Two methods were used for creating PP‐bearing biocides. One way involves melt‐blending of biocides and PP and subsequent injection molding to create the desired antimicrobial PP surface. Another technique consists of thermal embossing of antimicrobial agents on the PP surface. The biocide‐bearing PP surfaces were evaluated against Escherichia coli (E. coli) K‐12 MG1655) for up to 24 h. In the case of injection‐molded PP system, leachable CuCl2·2H2O showed a 5.87 ± 0.01 log reduction after 24 h, but only 0.47 ± 0.03 log reduction for PP bearing nonleachable Mg(OH)2. On the contrary, thermally embossed PP with CuCl2·2H2O and Mg(OH)2 showed 2.28 ± 0.03 and 3.78 ± 0.03 log reductions, respectively, after 24 h. The nonleachable Mg(OH)2 imparted antimicrobial properties only to the PP surface prepared via thermal embossing. In contrast, owning to the leachable copper ions, leachable CuCl2·2H2O biocides imparted PP surfaces antimicrobial irrespective of the molding or surface embossing approach. This approach provides an advantage for nonleachable PP‐based antimicrobial surfaces in overcoming the toxicity concern associated with plastics bearing leachable biocides.

Mechanical characteristics of reclaimed carbon fibre under superheated steam atmosphere and its feasibility for remanufacturing CFRP/CFRTP

This study is performed to investigate the effect of using superheated steam (SHS) in pyrolysis reclamation on the mechanical properties of reclaimed carbon fibres. The mechanical characteristics of the reclaimed fibres are evaluated by analysing their tensile strength and fracture toughness. The feasibility of the reclaimed fibres is assessed by using them to remanufacture composites with epoxy and polypropylene matrices. The performance of the remanufactured composites is evaluated via mechanical testing. The test results show that using SHS in pyrolysis effectively prevents the degradation of the reclaimed carbon fibres. Variations in the tensile strength and fracture toughness of the reclaimed fibres are lower when pyrolysis is performed under a SHS atmosphere. Moreover, the mechanical characteristics of the remanufactured composites show that using SHS during pyrolysis reduces the degradation of the bending strength and Izod impact strength.

Improving the shear resistance of ground technological quarry roads on loosely-bound subgrades

The study aims to solve the urgent problem of strengthening the subgrade of roads for heavy-duty vehicles. In the case of a limited road service life, it appears economically unfeasible to provide a strong cement-concrete subgrade. This case requires a solution maximizing the use of both local materials and production wastes, available in the work area. In order to perform calculations of stresses, arising at a great depth in the subgrade of the technological road under the influence of heavy-duty vehicle wheels, it is necessary to use appropriate mathematical models. In the present study, the calculations were carried out using a software application that implements the method of discrete elements. Using this method, stresses in highly inhomogeneous granular media can be calculated using the first[1]principle approach. The design of road structural layers suggests the use of geocontainers, made of used polypropylene big bags at the subgrade, which, due to their large size, have a greater shear resistance when filled with any soil mixture. The durability of the polypropylene fabric in the roadbed can reach several decades. The main task of the study was to calculate the protective layer of alternated crushed stone, clay soil, and polypropylene fabric. The thickness of layers was selected such that the tensile stresses during the passage of vehicles on the surface of a geocontainer remain within the strength limits of the container shell material.