Erucamide is used as an important slip agent for polymers. However, erucamide can degrade during processing and long-term storage, forming various oxidation products. These degradation products can ...affect the recovery rates of erucamide. In this study, investigated different solid–liquid extraction methods (Soxhlet, microwave, and ultrasound) and used gas chromatography with mass spectrometry (GC-MS) to quantify erucamide and its degradation byproducts in polypropylene (PP). A multivariable experiment was designed, and a mixed-effect approach was used to analyze the results. Various extraction variables were examined, such as temperature, time, solvents, and PP pretreatments. Using a mixed-effect model with a Kenward–Roger approximation, an R2 of the model of 97% and p values of 0.168, 0.000, and 0.000 were obtained for the technical, solvent, and type of PP pretreatment variables, respectively. The highest average recoveries of erucamide were found with the microwave technique and were 96.4% using dichloromethane, 94.57% using cyclohexane, and 93.05% using limonene. With ultrasound, recoveries ranged between 85 and 92% for dichloromethane and limonene. In addition, it was observed that the extraction method had better recovery results in ground PP than in films and in pellets. Nine oxidative degradation byproducts of erucamide were identified and semi-quantified by GC-MS. The reaction mechanisms for forming each byproduct were proposed. The byproducts that experienced a higher rate of degradation of erucamide were erucamide with a hydroxyl group at position one and 12-amino-6-12-oxo-dodecanoic acid, showing more prominent peaks using the Soxhlet method with cyclohexane and dichloromethane as solvents and polypropylene (PP) films as the type of material used.
Effects of Different Polypropylene Momeni, Vahid; Shahroodi, Zahra; Gonzalez-Gutierrez, Joamin ...
Polymers,
07/2023, Letnik:
15, Številka:
14
Journal Article
Recenzirano
The current study presents the effect of the backbone as an important binder component on the mechanical, rheological, and thermal properties of Aluminium (Al) alloy feedstocks. A thermoplastic ...elastomer (TPE) main binder component was blended with either polypropylene (PP), grafted-maleic anhydride-PP (PPMA), or grafted-maleic anhydride-PPwax (PPMAwax) plus PP, as the backbone. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests were performed to investigate the thermal properties of binder systems and feedstocks. Fourier-transform infrared (FTIR) spectroscopy was used to study the chemical interaction between the binder and the Al alloy. After making feedstock filaments, tensile tests, scanning electron microscopy (SEM), and fused filament fabrication (FFF) printing were done. The results showed that although the PP printability was acceptable, the best mechanical properties and printed quality can be achieved by PPMA. TGA test showed that all binder systems in the feedstocks could be removed completely around 500 °C. From FTIR, the possibility of chemical reactions between Al alloy particles and maleic anhydride groups on the grafted PP backbone could explain the better dispersion of the mixture and higher mechanical properties. Tensile strength in PP samples was 3.4 MPa which was improved 1.8 times using PPMA as the backbone.
Polypropylene (PP) and polystyrene (PS) underwent a comprehensive investigation into their mechanical and chemical degradation through reactive molecular dynamics simulations. The simulations ...utilized the ReaxFF force field for CHO (carbon-hydrogen-oxygen) systems in the combustion branch. The study included equilibrium simulations to determine densities and melting temperatures, non-equilibrium simulations for stress-strain and Young moduli determination, mechanical cleaving to identify surface species resulting from material fragmentation, and shock compression simulations to elucidate chemical reactions activated by some external energy sources. The results indicate that material properties such as densities, phase transition temperatures, and Young moduli are accurately reproduced by the ReaxFF-CHO force field. The reactive dynamics analysis yielded crucial insights into the surface composition of fragmented polymers. Both polymers exhibited backbone breakage, leaving -CH2· and –CH·- radicals as terminals. PP demonstrated substantial fragmentation, while PS showed a tendency to develop crosslinks. A detailed analysis of chemical reactions resulting from increasing activation due to increasing value of compression pressure is presented and discussed.
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•ReaxFF effectively predicts the material properties of polymers and their degradation.•Cleaving with ReaxFF generates –CH2.● and –CH● radicals on the surfaces•Shock compression results in unconventional connections within bulk materials.•Shock compression leads to degradation of molecular structure of polymers.•Degraded polymers reveal numerous unconventional chemical connections.
Improving the residual char of polypropylene (PP) is difficult due to the preferential complete combustion. Here, we designed a combination catalyst that not only provides physical barrier effects, ...but also dramatically promotes catalytic charring activity. We successfully synthesized WSsub.2 monolayer sheets decorated with isolated Ni atoms that bond covalently to sulfur vacancies on the basal planes via thiourea. Subsequently, PP blends composed of 8 wt.% Ni-decorated WSsub.2, NiO, and activated carbon (AC) were obtained (sup.ENi-sup.SWSsub.2-AC-PP). Combining the physical barrier effects of WSsub.2 monolayer sheets with the excellent catalytic carbonization ability of the sup.ENi-sup.SWSsub.2-AC combination catalyst, the PP blends showed a remarkable improvement in flame retardancy, with the yield of residual char reaching as high as 41.6 wt.%. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, it was revealed that the microstructure of residual char contained a large number of carbon nanotubes. The production of a large amount of residual char not only reduced the release of pyrolytic products, but also formed a thermal shield preventing oxygen and heat transport. Compared to pure PP, the peak heat release rate (pHRR) and total heat release rate (THR) of sup.ENi-sup.SWSsub.2-AC-PP were reduced by 46.32% and 26.03%, respectively. Furthermore, benefiting from the highly dispersed WSsub.2, the tensile strength and Young’s modulus of sup.ENi-sup.SWSsub.2-AC-PP showed similar values to pure PP, without sacrificing the toughness.
•The recent advances on the application of synthetic fibers in FRCC are reviewed.•Properties of three types of synthetic fibers, namely polypropylene, polyethylene and polyvinyl alcohol are ...described.•Important parameters affecting the influence of synthetic fibers on properties of FRCCs is critically reviewed.•Physical and mechanical properties of FRCCs and their variation with key parameters are discussed.
Owing to their remarkable physical and mechanical properties, the use of polypropylene (PP), polyethylene (PE), and polyvinyl alcohol (PVA) fibers in cementitious composites has received significant attention in recent years. This paper presents an in-depth review of the recent advances on the use of these synthetic fibers in cementitious composites as reinforcement. The fibers are categorized on the basis of their physical and mechanical properties. Throughout the review, the key fiber parameters have been identified and their influence on the physical, mechanical, and durability properties of fiber-reinforced cementitious composites (FRCCs) are discussed. To explain the observations of these properties, microstructure analyses of the composites and fibers are also presented.
In order to promote the engineering application of recycled concrete, the effects of PPF and nano-TiO2 dioxide on the mechanical properties and durability of recycled concrete were studied. ...Polypropylene fiber recycled concrete(PRAC) and nano-TiO2 recycled concrete(TRAC) were prepared by adding different volume contents of PPF and nano-TiO.sub.2. The experimental findings demonstrated that the PPF and nano-TiO.sub.2 improved the splitting tensile strength of RAC better than the compressive strength. When the volume content of nano-TiO.sub.2. and PPF is 0.8% and 1.0%, respectively, the corresponding splitting tensile strength of concrete reaches the maximum value(3.4 and 3.7 MPa). The contribution rates of nano-TiO.sub.2 and PPF with different volume contents to the mechanical properties of RAC have optimal values, which are 0.4 and 1.0%, respectively. The incorporation of nano-TiO.sub.2 and PPF can effectively inhibit the loss of RAC mass and the generation of pores under freeze-thaw conditions, and slow down the decrease of dynamic elastic modulus. When the volume content of PPF is 1.0% and the volume content of nano-TiO.sub.2 is 0.4%, the protection effect on the internal structure of RAC is better, and its carbon resistance is better. The results of RSM model analysis and prediction show that both PPF and nano-TiO.sub.2 can be used as admixture materials to improve the mechanical properties and durability of RAC, and the comprehensive improvement effect of PPF on RAC performance is better than that of nano-TiO.sub.2.
This research aims to investigate the fresh and mechanical properties of concrete with diatomaceous earth (DE) and polypropylene fiber (PPF). The cement was partially replaced by DE in the ...concentration ranging from 5 to 20% by weight; whereas, PPF was incorporated in concrete mix as in range of 0.05-0.20% by cement weight. Totally, 25 different mix proportions were developed and their fresh properties were examined using slump, density and compacting factor tests. Besides, mechanical properties were evaluated by. Using compressive, split tensile, and flexural strength analysis at the ages of 7th, 14th and 28th days. Furthermore, concrete durability properties were evaluated using water penetration, chloride permeability as well as sorptivity tests, which have been performed at the age of 28th day. The result exhibits that the incorporation of D.E slightly affects the slump value meanwhile PPF decreases the fresh values. Furthermore, the combination of DE and PPF in concrete significantly enhances the mechanical properties compared to the control mix. The mix proportion of 15% DE and 0.15% of PPF exhibited a noticeable influence on mechanical properties as well as durability properties compare to control concrete.
In this study, the interactions between microplastics, chosen among the most widely used in industry such as polypropylene (PP) and high-density polyethylene (HDPE), and a model freshwater ...microalgae, Chlamydomas reinhardtii, were investigated. It was shown that the presence of high concentrations of microplastics with size >400 μm did not directly impact the growth of microalgae in the first days of contact and that the expression of three genes involved in the stress response was not modified after 78 days. In parallel, a similar colonization was observed for the two polymers. However, after 20 days of contact, in the case of PP only, hetero-aggregates constituted of microalgae, microplastics and exopolysaccharides were formed. An estimation of the hetero-aggregates composition was approximately 50% of PP fragments and 50% of microalgae, which led to a final density close to 1.2. Such hetero-aggregates appear as an important pathway for the vertical transport of PP microplastics from the water surface to sediment. Moreover, after more than 70 days of contact with microplastics, the microalgae genes involved in the sugar biosynthesis pathways were strongly over-expressed compared to control conditions. The levels of over-expression were higher in the case of HDPE than in PP condition. This work presents the first evidence that depending on their chemical nature, microplastics will follow different fates in the environment.
•The presence of microplastics in high concentration did not directly impact microalgae growth.•Gene transcripts involved in sugar biosynthesis were differently over-expressed depending on the polymer nature.•Hetero-aggregates were formed only in the case of polypropylene fragments.
This work investigates the interaction between microplastics and microalgae showing that the long-term colonization of plastics is dependent on the nature of the polymers.
Nowadays lithium-ion batteries are widely used in many electrical equipments. Separators are a key component in lithium-ion batteries (LIBs) and perform an important role in the performance and ...safety of batteries. Weak wettability and termal resistance of polyolefine separators cause to limit their efficiency in LIBs. In the current research, the surface of a commerical PP separator was modified by polyvinyl alcohol (PVA)-SiO.sub.2 coating layer using the electrospining method. Gurley test was conducted to obtain the permability of the designed separators. Surface tension, viscosity and electrical conductivity of the electrospining solution were also measured. The electrospining parameters (concentration of PVA and SiO.sub.2, voltage and time) were optimized via an experimental design. The obtained results showed that, the shrinkage was minimized for the solution of 7.5wt%PVA-15wt%SiO.sub.2 which was fabricated at 16.7 kV for 1.5 h. It was revealed that addition of SiO.sub.2 nanoparticles as well as incraesing the concentration of the electrospining solution led to increase in viscosity and surface tension of separators. Si-O-Si absorbtion peaks were appeared in FTIR spectrum of PVA-SiO.sub.2 fibers compared to PVA fibers. Addition of 20 wt% SiO.sub.2 nanoparticles to 12 wt% PVA solution increased the elecrical conductivity from 712 mum to 725 mum. The discharge rate capability results showed that the optimized coated separator had the ability to deliver 61% of initial capacity while the pristine separator delivered 41%, at the same C-rate. Finally the optimized coated separator exhibited the capacities retention of 93% with respect to 87% for pristine separator after 50 cycles.
The morphological transformation of extruded polypropylene (PP) films from the mesophase to α-form crystals has been investigated. Extruded PP films prepared by quenching had the mesophase morphology ...with a nearly-random orientation of the molecular chains. The mesophase structure of the quenched PP films completely transformed to α-form crystals by annealing at 100 °C accompanied by enhancement of the molecular orientation along the machining direction (MD). Moreover, the annealed films expanded and shrank by approximately 0.5% along the MD and transverse direction (TD), respectively. The unusual expansion behavior during annealing suggests that a small amount of oriented molecular chains formed in the extruded film, and the oriented chains acted as a nucleating agent. Consequently, the molecular orientation along the MD was enhanced owing to the morphological transformation. The oriented chains also acted as nucleating agent during tensile deformation, resulting in a significant improvement of strength in the MD stretching.
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•We investigated the morphological transformation from mesophase to α-form crystals.•The molecular orientation was enhanced during the morphological transformation.•The extruded polypropylene films expanded in the MD after annealing.•Only a few oriented chains existing in the extruded films acted as nucleating agents.
