PP Concentration Research Articles

Study of mechanical and rheogical properties of HDPE/iPP cross-linking polymer blends

The rapidly developing subject of polymer mix design presents prospects for the creation of materials with precisely customised qualities. It's crucial to comprehend the morphology that results from blending immiscible polymers for obtaining the required mechanical qualities. This study explores the complex interactions between structure and characteristics in both cross-linked and unmodified blends of HDPE and iPP. Our study provides important new information by combining mechanical testing and rheological evaluations. It is observed that materials that are cross-linked have a significantly higher viscosity, which suggests the establishment of a three-dimensional network and improved stability. Furthermore, HDPE exhibits enhanced behaviour after crosslinking. After crosslinking, the melt flow index decreases, indicating increased resistance to flow and deformation because more interchain links are formed. Higher PP concentration in unmodified blends results in greater flexibility and ductility, but cross-linking causes rigidity. On the other hand, cross-linking improves flexibility by reducing rigidity in mixes with a lower iPP concentration. Additionally, the combination of iPP and crosslinking agents results in a significant improvement in mechanical strength, which reinforces structural integrity. Crosslinking also improves impact resistance, making the materials appropriate for uses requiring strong performance in demanding circumstances.

Photocatalytically active layered double hydroxide-PVDF composite membranes for effective remediation of dyes contaminated water

In this work, polyvinylidene fluoride (PVDF) intercalated CuFe layered double hydroxides (LDH) membranes were fabricated and investigated for UV-LED/persulfate degradation of methylene blue (MB), crystal violet (CV), methyl orange (MO), and Eriochrome black T (EBT) dyes from water. The PVDF-CuFe membrane exhibited improved heterogeneity, surface functionality (CuO, Fe–O, Cu–O–Fe), surface roughness, and hydrophilicity. The process parameters were optimized by response surface methodology, and maximum MB removal (100%) was achieved within 45.22–178.5 min at MB concentration (29.45–101.93 mg/L), PP concentration (0.5–2.41 g/L) and catalyst dosage (1.84–1.95 g/L). The degradation kinetics was well described by a pseudo-first-order model (R2 = 0.982) and fast reaction rate (0.029–0.089/min). The MB dye degradation mechanism is associated with HO·/SO4•− reactive species generated by Fe3+/Fe2+ or Cu2+/Cu+ in PVDF-CuFe membrane and PP dissociation. The PVDF-CuFe membrane demonstrated excellent recyclability performance with a 12% reduction after five consecutive cycles. The catalytic membrane showed excellent photocatalytic degradation of crystal violet (100%), methyl orange (79%), and Eriochrome black T (60%). The results showed that UV-LED/persulfate-assisted PVDF-CuFe membranes can be used as a recyclable catalyst for the effective degradation of dye-contaminated water streams.

Nitrogen fertilization and arbuscular mycorrhizal fungi do not mitigate the adverse effects of soil contamination with polypropylene microfibers on maize growth

Soil contamination with microplastics may adversely affect soil properties and functions and consequently crop productivity. In this study, we wanted to verify whether the adverse effects of microplastics in the soil on maize plants (Zea mays L.) are due to a reduction in nitrogen (N) availability and a reduced capacity to establish symbiotic relationships with arbuscular mycorrhizal (AM) fungi. To do this, we performed a pot experiment in which a clayey soil was exposed to two environmentally relevant concentrations of polypropylene (PP; one of the most used plastic materials) microfibers (0.4% and 0.8% w/w) with or without the addition of N fertilizer and with or without inoculation with AM fungi. The experiment began after the soil had been incubated at 23 °C for 5 months. Soil contamination with PP considerably reduced maize root and shoot biomass, leaf area, N uptake, and N content in tissue. The adverse effects increased with the concentration of PP in the soil. Adding N to the soil did not alleviate the detrimental effects of PP on plant growth, which suggests that other factors besides N availability played a major role. Similarly, although the presence of PP did not inhibit root colonization by AM fungi (no differences were observed for this trait between the uncontaminated and PP-contaminated soils), the addition of the fungal inoculum to the soil failed to mitigate the negative impact of PP on maize growth. Quite the opposite: mycorrhization further reduced maize root biomass accumulation. Undoubtedly, much research remains to be done to shed light on the mechanisms involved in determining plant behavior in microplastic-contaminated soils, which are most likely complex. This research is a priority given the magnitude of this contamination and its potential implications for human and environmental health.

Pyrophosphate ions inhibit calcium phosphate cement reaction and enable storage of premixed pastes with a controlled activation by orthophosphate addition

The standard preparation routine of a calcium phosphate cement includes mixing a solid and a liquid component (reactive cement powder and mixing liquid) in an open bowl at the operating theatre. This poses the risk of preparation-related deviations of the resulting properties when the cements are mixed by different persons. Hence, facilitating this mixing procedure is highly desirable. It can be achieved by application of premixed cement pastes: The mixing liquid and a stable suspension of the cement powder are assembled and mixed in a special syringe, minimizing the impact of these preparation-related effects.In this study, a suspension of reactive α-tricalcium phosphate powder in water was stabilized by sodium pyrophosphate decahydrate (PP). Controlled activation of these premixed pastes was then accomplished by adding a concentrated Na2HPO4/NaH2PO4 (Na2/Na) solution. Systematic assessment of the activation mechanism, including the effect of the PP concentration and the amount of Na2/Na added, was performed by isothermal calorimetry, quantitative in-situ X-ray diffraction, rheological characterization and automated Gillmore needle measurements at 37 °C.Premixed pastes with addition of at least 0.05 wt% PP were successfully stabilized for up to 2 weeks at 25 °C, and even 4 weeks at 4 °C. This pre-storage had no significant impact on the setting performance of the pastes. Increasing the PP concentration at constant Na2/Na amount systematically retarded the setting reaction, while an elevated quantity of Na2/Na addition at constant PP concentration resulted in an acceleration.Based on these results, a composition stabilized with 0.05 wt% PP and activated with 20.8 vol% Na2/Na related to the amount of liquid in the premixed pastes appears ideal with respect to the desired setting performance.

TPV: A New Insight on the Rubber Morphology and Mechanic/Elastic Properties

The objective of this work is to study the influence of the ratio between the elastomer (EPDM) phase and the thermoplastic phase (PP) in thermoplastic vulcanizates (TPVs) as well as the associated morphology of the compression set of the material. First, from a study of the literature, it is concluded that the rubber phase must be dispersed with a large distribution of the domain size in the thermoplastic phase in order to achieve a high concentration, i.e., a maximal packing fraction close to ~0.80. From this discussion, it is inferred that a certain degree of progress in the crosslinking reaction must be reached when the thermoplastic phase is melted during mixing in order to achieve dispersion of the elastomeric phase in the thermoplastic matrix under maximum stress. In terms of elasticity recovery which is measured from the compression set experiment, it is observed that the crosslinking agent nature (DCP or phenolic resin) has no influence in the case of a TPV compared with a pure crosslinked EPDM system. Then, the TPV morphology and the rubber phase concentration are the first order parameters in the compression set of TPVs. Finally, the addition of carbon black fillers leads to an improvement of the mechanical properties at break for the low PP concentration (20%). However, the localization of carbon black depends on the crosslinking chemistry nature. With radical chemistry by organic peroxide decomposition, carbon black is located at the interface of EPDM and PP acting as a compatibilizer.

Identification of novel paraben-binding peptides using phage display

Parabens are alkyl esters of 4-hydroxybenzoic acid, which is derived from a family of synthetic esters of p-hydroxybenzoic acid. Among all the kinds of paraben, two parabens (methyl paraben, MP; and n-propyl paraben, PP) are the most generally used as preservatives in personal care products, such as cosmetics, pharmaceuticals, and food also, and are often presented together. However, a number of studies have reported that the toxicity of parabens affects the water environment, and human as well. This study utilized M13 phage display technology to provide easy, efficient, and relatively inexpensive methods to identify peptides that bind to MP and PP, respectively, to remove in wastewater. At first, biopanning was performed, to sort MP and PP specific binding phages, and three cases of experiment, including negative control (NC), which could sort unspecific binding phage, were conducted at the same time. Phage binding affinity tests were substituted by concentration reduction using antibody conjugated magnetic beads, and paraben concentration was measured by HPLC. Analysis showed that the MP concentration reduction of 38% was the highest in M4 phage, while the PP concentration reduction of 44% was the highest in P3 phage. We successfully screened two peptides specific to MP and PP, namely, MP4 and PP3, respectively; the results showed that the MP concentration reduction in MP4 was the highest at 44%, and the PP concentration reduction in PP3 was the highest at 39%, and their specificity was measured by the capture rate between target and control. In conclusion, the phage display technique shows applicability to the removal of parabens in water; furthermore, it also shows the possibility of the detection or removal of other chemicals.

Biocomposites based on plasticized starch: thermal, mechanical and morphological characterization

In this research, a composite material based on thermoplastic starch (TPS) obtained from pich seeds (Enterolobium cyclocarpum) filled with solid particles of their own shell (PP) was elaborated and fully characterized by different techniques such as DSC, TGA, FTIR, tensile test and SEM. All composites showed good dispersion of the shell particles within the matrix. Particles size and concentration effect over the mechanical, morphologic and thermic properties were studied. Calorimetric characterization by DSC exhibited an increment in ΔHf as PP concentration was increased, while TGA analysis shown thermal events associated to decomposition of hemicellulose followed by cellulose and finally lignin components. Pich TPS/PP composite material FTIR spectrum clearly displayed absorption bands corresponding to amylose and amylopectin, cellulose, hemicellulose and lignin organic groups. SEM analysis identified average diameters in shell particles (PP) around 1180 μm, 600 μm and 425 μm. Higher mechanical properties corresponding to maximum stress (σmax) and elastic modulus (E) were obtained for composites manufactured with particle size of 600 µm and 5% concentration. These results are consistent with the static mechanical behaviour, which vary according to the filler content. It is shown that the addition of PP fillers improves the thermal resistance and mechanical properties of these biocomposites.

Rheological and microstructural characterization of batters and sponge cakes fortified with pea proteins

The effect of pea protein fortification on the rheological properties of sponge-cake batters and their continuous phases, as well as their relationship with the final product properties were studied. Foams made out of whole egg and sugar were prepared in a planetary mixer; wheat flour (WF) was added to form a typical sponge-cake batter. Pea protein isolates (PP) were added in substitution to WF to form five batters with various PP concentrations expressed as the percentage of WF substitution: 0, 10, 20, 30 and 40%. The batter air volume fraction decreased when increasing PP concentration, which led to an increase in the cake density and apparent Young modulus. All batters and their respective continuous liquid phases showed shear-thinning behavior, which was modeled by a power law. They showed a predominant elastic behavior at intermediate frequencies, and a cross-over point at high frequencies. All of the rheological properties increased by a factor of about 10 when the PP concentration increased from 0 to 40%. Free-drainage experiments showed that batter stability increased with increasing PP concentration. PP had larger particles than WF, and showed a higher water binding capacity than WF, but no significant difference in solubility. Observations of the batter and cake microstructure revealed PP formed a network of interconnected “bridged” particles in the continuous phase. These results suggest that PP first acted as fillers that swelled and connected to each other in the continuous phase, and were the main driver for the increase of rheological properties.

Mn(III)-ligand complexes as a catalyst in ligand-assisted oxidation of substituted phenols by permanganate in aqueous solution

Ligands can significantly increase the oxidation rates of phenolic compounds by MnO4−. This was often explained by the in situ formed Mn(III)- or Mn(X)-ligand complexes that can oxidize phenols faster than MnO4− can. This work discovered that Mn(III)-ligand complexes also acted as a catalyst for the oxidation of phenolic compounds by MnO4− (i.e., the catalytic role of Mn(III)-ligand). First, when phenol was mixed with MnO4− and pyrophosphate (PP, a representative ligand), Mn(III)-PP was found to form while phenol was quickly oxidized. However, the amount of phenol that was directly oxidized by Mn(III)-PP only accounted for ∼25% of phenol that was oxidized in the mixture, indicating that there were other pathways. Then, when pentachlorophenol (PCP) was used as another phenolic probe, the externally prepared Mn(III)-PP was observed to only slightly oxidize PCP, but its addition significantly accelerated PCP oxidation by MnO4−. The Mn(III)-PP concentration also remained unchanged during the above reaction, thus suggesting the catalyst role of Mn(III)-PP. This new pathway was further validated by successfully explaining all the experimental observations obtained so far, including the effect of pH, effects of different ligand amounts and types, product patterns, and the induction period. Finally, possible catalytic mechanisms of Mn(III)-ligand were discussed based on the experimental results.

Tensile characteristics for a class of polymeric blends (PP + PA6)

This paper presents the influence of component concentration of a class of polymeric blends with different concentration of PP and PA6 and a constant concentration of additives (CaCO3, LDPE and an adhesive) Young’s modulus does not have a clear tendency of depending on PA6 concentration and testing speeds, but performs in a band between 1500…1900 MPa, except for the value for PA6 at the lowest testing speed (v=10 mm/min), that is 1454.8 MPa. Under large testing speeds, there were cracks or voids towards the loading direction, forming large parallel ‘empty channels’. Investigations are done on possible causes of these longitudinal voids in order to clear if they occur during molding or/and during testing and to eliminate them. Except for values at low testing speed, the average values for tensile stress at break perform in a band of less than 8 MPa. The elongation at break is less than 10% for all materials, except for PA6 at the lowest testing speed, when the highest value for this characteristic was obtained. The lowest values were obtained for material with 20% PA6. For blends with 60% and 80% PA6, the difference between values, at the same testing speed, is the smallest. Energy at break has a slightly increase with the concentration of PA6. From the mechanical point of view, among the formulated blends, material D (with 80% PA6) is the most promising as has the highest stress and energy at break (11.43 J at v=10 mm/min and 8.7 J at v=1000 mm/min), but values are still less than those for PA6.

Percutaneous permeability of 1-phenoxy-2-propanol, a preservative in cosmetics

1-Phenoxy-2-propanol (PP) is used as a preservative in cosmetics. PP is currently permitted to be used to up to 1% in cosmetic formulations in Korea and Europe. For risk assessment, percutaneous absorption is a crucial factor, but dermal absorption of PP has not yet been reported. In this study, Franz diffusion method was used to determine the percutaneous penetration of PP using the dorsal skin of rats. Each formulation of shampoo or cream, 113.6 mg/cm2, was applied to a donor compartment of Franz diffusion cell for 24 h. Receptor fluid was collected at 0, 1, 2, 4, 8, 12, and 24 h following dermal application. Remaining formulation was removed with a cotton swab after last sampling. Using tape stripping method, stratum corneum was removed. PP in epidermis and dermis was extracted in PBS for 24 h. The concentration of PP from the swab, stratum corneum, and epidermis and dermis samples was determined using high performance liquid chromatography. Total percutaneous absorption rates of PP for shampoo and cream were 50.0 ± 6.0% and 33.0 ± 3.2%, respectively. In vitro skin permeability was calculated as 1,377.2 ± 240.1 mg/cm2 for shampoo and 1,038.0 ± 72.2 mg/cm2 for cream for 24 h

Levels of organochlorine pesticides in Amazon turtle (Podocnemis unifilis) in the Xingu River, Brazil

Due to the toxicity and high environmental persistence of organochlorine pesticides in aquatic organisms, turtles have been studied as environment biomonitors. These animals are important sources of protein for the riverside and indigenous peoples of the Brazilian amazon. In the present study, organochlorine pesticide contamination was investigated in Podocnemis unifilis. Liver, muscle and fatty tissue samples were removed from 50 specimens collected from five sampling points located in the Xingu River basin. Fourteen organochlorine pesticides were analysed via gas chromatography with an electron capture detector (CG-ECD). Eight organochlorine pesticides were detected with average concentrations of ∑DDT, ∑Endossulfan and ∑HCH which were 26.17 ± 26.35, 14.38 ± 23.77 and 1.39 ± 8.46 ng g−1 in moisture content, respectively. DDT compounds were the most predominant, with a greater concentration of pp′-DDT in the liver and pp′-DDD in the muscle. Significant differences were noted between the types of tissues studied, and the concentration of OCPs varied between sampling sites.

Analysis of Reaction Kinetics of CO2 Absorption into a Novel 1-(2-Hydroxyethyl)-piperidine Solvent Using Stopped-Flow Technique

In this present work, the absorption kinetics of CO2 into aqueous 1-(2-Hydroxyethyl) piperidine (1-(2-HE)PP) solutions with respect to observed pseudo-first-order rate constant (k0) and second order reaction rate constant (k2), were determined using the stopped-flow apparatus within the 1-(2-HE)PP concentration range of 0.20–1.00 kmol/m3 and a temperature range of 293–313 K. The values of k0 were then represented using the correlation based on the base-catalyzed hydration mechanism. The results show that the correlated values of k0 matched well with the experimental values with an acceptable AAD of 8.3%, which indicates that the base-catalyzed hydration mechanism can satisfactorily describe the experimental kinetics data of the1-(2-HE)PP reaction with CO2. In order to comprehensively understand the kinetics, the ion speciation plots of 1-(2-HE)PP-H2O–CO2 system were developed using the pH method. In addition, the Bronsted plots between k2 (obtained from stopped-flow apparatus) and pKa (obtained from exper...

Coloring Rate of Phenolphthalein by Reaction with Alkaline Solution Observed by Liquid-Droplet Collision.

Many important chemical reactions are induced by mixing two solutions. This paper presents a new way to measure rates of rapid chemical reactions induced by mixing two reactant solutions using a liquid-droplet collision. The coloring reaction of phenolphthalein (H2PP) by a reaction with NaOH is investigated kinetically. Liquid droplets of H2PP/ethanol and NaOH/H2O solutions are made to collide, which induces a reaction that transforms H2PP into a deprotonated form (PP(2-)). The concentration of PP(2-) is evaluated from the RGB values of pixels in the colored droplet images, and is measured as a function of the elapsed time from the collision. The obtained rate constant is (2.2 ± 0.7) × 10(3) M(-1) s(-1), which is the rate constant for the rate-determining step of the coloring reaction of H2PP. This method was shown to be applicable to determine rate constants of rapid chemical reactions between two solutions.

Understanding the foamability and mechanical properties of foamed polypropylene blends by using extensional rheology

ABSTRACTIn this article, the influence of the rheological behavior of miscible blends of a linear and a high melt strength, branched, polypropylene (HMS PP), on the cellular structure and mechanical properties of cellular materials, with a fixed relative density, has been investigated. The rheological properties of the PP melts were investigated in steady and oscillatory shear flow and in uniaxial elongation in order to calculate the strain hardening coefficient. While the linear PP does not exhibit strain hardening, the blends of the linear and the HMS PP show pronounced strain hardening, increasing with the concentration of HMS PP. Related to the cellular structure, in general, the amount of open cells, the cell size, and the width of the cell size distribution increase with the amount of linear PP in the blends. Also mechanical properties are conditioned by the extensional rheological behavior of PP blends. Cellular materials with the best mechanical properties are those that have been fabricated using large amounts of HMS PP. The results demonstrate the importance of the extensional rheological behavior of the base polymers for a better understanding and steering of the cellular structure and properties of the cellular materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42430.

Physicochemical alterations in liposomes induced by low concentrations of synthetic antioxidant potassium phenosan

We have recently shown by spin probe ESR that synthetic antioxidant potassium β�(4 �hydroxy�3,5�di� tertbutylphenyl)propionate (potassium phenosan, PP) can modify the structural state of surface (8 A) and deeplying (20-22 A) regions of lipids of plasmatic membranes isolated from mouse liver cells in a wide concentration range (10 ⎯5 ⎯10 -21 M) in vitro (1, 2). Nonlinear bimodal dose-effect dependences were obtained for parameters that characterize the micro� viscosity of lipid bilayer (τc) in the location region of nitroxyl fragment of 16�doxylstearic acid ( С16) probe and for ordering parameter (S) that characterizes the rigidity of surface lipid layers in the location area of 5� doxylstearic acid (С5) probe. It was established that a statistically significant increase in τ c parameter was observed at the PP con� centration of 10 -5 -10 -7 and 10 -18 -10 -19 M, while that in S parameter was detected at a concentration of 10 -6 -10 -7 and 10 -13 -10 -15 M. Effect maxima were

Vemurafenib: an unusual UVA‐induced photosensitivity

Vemurafenib is a new-targeted therapy approved for the treatment of patients with V600E BRAF-mutant metastatic melanoma. Among the cutaneous adverse events reported, the photosensitivity is frequently experienced. We aimed to characterize more deeply the mechanism leading to this photosensitivity as well as the corresponding UV spectrum. Phototests showed that the phototoxicity was UVA-dependent since from normal value prior to vemurafenib treatment, the UVA-minimal erythema dose decreased in 17 of 18 patients (94.4%) while the minimal erythema dose remained unchanged. Furthermore, a vemurafenib-induced erythema appeared quickly during the UVA exposure contrarily to what is observed with a conventional drug-induced phototoxicity showing an erythema 12-24h after the phototesting. Vitamin PP concentration decreased, and porphyrin level significantly increased after 2months of vemurafenib. Our study confirms the high risk of vemurafenib-induced photosensitivity and indicates that it is possibly vitamin PP- and porphyrin dependent.

Facile Preparation of the Superhydrophobic Surface on Aluminum Alloy by PP-Coating

We investigated the preparation of the superhydrophobic surface on aluminum alloy by PP coating. The effects of PP concentration and duration on the surface were discussed. The contact angle (CA) was measured by an optical contact angle meter and the morphology of the surface was observed by a scanning electron microscope. The result showed that the superhydrophobic surface on aluminum alloy could be facilely fabricated by direct PP coating with a suitable concentration. It was confirmed by SEM that the superhydrophobic surface was resulted from the micro/nano-structure of PP. However, the CA became much lower as time went on. It was indicated that the duration of the superhydrophobic surface on aluminum alloy by direct PP coating was poor and a suitable method for improving the duration should be adopted.

An investigation of carbon steel corrosion inhibition in hydrochloric acid medium by an environmentally friendly green inhibitor

The inhibition effect of polyphenols extracted from olive mill wastewater (PP) on carbon steel in 1.0 M HCl solution was studied. Inhibition efficiency of PP was carried out by using chemical (weight loss method) and electrochemical techniques [potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)]. The effect of temperature and immersion time on the corrosion behavior of carbon steel in 1.0 M HCl with addition of an extract was also studied. The results show that PP acts as a very good inhibitor, and the inhibition efficiency increases with the concentration of PP and decreases with rising temperature. Polarization curves show that PP behaves as a mixed-type inhibitor in hydrochloric acid. Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through an appropriate equivalent circuit model; a constant phase element has been used. EIS shows that charge-transfer resistance increases and the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. The activation energy as well as other thermodynamic parameters for the inhibition process were calculated. The adsorption of PP obeys the Langmuir adsorption isotherm.

Short communication: Production of antihypertensive peptide HLPLP by enzymatic hydrolysis: Optimization by response surface methodology

This study evaluates the potential ability of proteolytic enzymes to release the antihypertensive peptide HLPLP, β-casein f(134–138), from caseinate. Corolase PP (Röhm GmbH & Co. KG, Darmstadt, Germany) was found as the most appropriate enzyme to produce this peptide. The optimization of the main experimental variables involved in the process [concentration of Corolase PP, concentration of Peptidase 433P (Biocatalysts Ltd., Parc Nantgarw, UK), and the hydrolysis time on the HLPLP concentration, expressed as area of peak] were studied using a central composite face design. The optimum conditions to obtain the maximum concentration of HLPLP provided by the statistical program were a concentration of Corolase PP of 60mg/g of protein and hydrolysis time of 24h. The use of the Peptidase 433P did not increase the amount of the active peptide. The obtained hydrolysate might be used as functional ingredient with antihypertensive properties.