Modification Of Polypropylene Research Articles

Modification of polyolefins utilizing C–H insertion of azides: Azidoformate end-functionalized polystyrene for modifying polypropylene

Polyolefins dominate the global plastics industry, constituting roughly 60% of all commercial plastics. However, their limited chemical functionality restricts their applicability in adhesion, printability, and compatibility-dependent applications. To overcome these limitations, this study investigated metal-free, melt-process post-polymerization modification of polypropylene (PP) via C-H insertion of azidoformate (AF) groups. We investigated grafting of AF end-functionalized polystyrene (PS) onto PP and demonstrated the successful preparation of novel PP hybrids with interesting properties, including enhanced compatibility between PP and PS components due to grafting, smaller PP crystallite size, high Young's modulus, and elastic rheological behaviors likely attributable to the presence of PS branches. Importantly, the presented approach avoids chain scission of PP and undesirable coloration of the product, offering a promising avenue for industrial transformations of conventional polyolefins. This research paves the way for developing polyolefin-based hybrid materials with enhanced properties and environmental benefits.

Modification of Polypropylene by Heterophase ZnO–Ag Nanoparticles

Modification of Polypropylene by Heterophase ZnO–Ag Nanoparticles

Post-polymerization modification of polypropylene with different functional groups utilizing non-catalytic C–H insertion of sulfonyl azide

This study presents a comprehensive investigation into the preparation of functionalized polypropylene (PP) with different functional groups, such as amino-, hydroxyl-, acetamido-, and carboxyl-groups, utilizing efficient C–H insertion capability of sulfonyl azide (SA) compounds with the functional groups. The reactive melt mixing of PP and the SA compounds was performed at temperatures determined by the decomposition temperatures of the SA groups, followed by purification processes to remove unreacted SA compounds, confirming the establishment of stable covalent linkages between the SA compounds and PP chains. Grafting efficiency (GE) values were determined using FT-IR spectroscopy, showcasing efficient grafting of the SA compounds onto PP chains with GE values ranging from 60 % to 70 %. Remarkably, SA compound with carboxyl functional group exhibited an exceptionally high GE value of ∼90 %, likely attributed to its electron-withdrawing carbonyl group. XRD analyses, thermal analyses, morphological analyses of cryogenically fractured modified PPs and mechanical property analyses revealed successful incorporation of SA compounds into PP chains with relatively low sensitivity of the crystal structure of the modified PPs to the incorporated SA compounds. Hydrophilicity assessments revealed improved paint adhesion capabilities of the modified PP surfaces, highlighting the potential for the tailored surface modification strategies to enhance material characteristics.

Optical properties of nanocomposites based on polypropylene modified by nanoparticles of oxide compounds

The optical properties in UV, visible and near IR spectral regions for nanocomposites based on polypropylene modified by nanoparticles of oxide compounds ZrO2, Al2O3, SiO2, MgO, TiO2, ZnO were studied. A shift of the main optical absorption edge to the short-wave region upon modification by dielectric nanoparticles (MgO, ZrO2, and Al2O3) was established. The absorption edge shifts to the long-wave region upon the introduction of semiconductor nanoparticles (ZnO, TiO2) and amorphous SiO2 particles. In all spectra, the absorption bands at 1200, 1400, and 1720 nm characterized by overtone vibrations of CH, CH2, and CH3 molecular groups were recorded. OH groups make a certain contribution to the bands at 1400 and 1720 nm. The dependence of the intensity of these absorption bands on the type and concentration of nanoparticles used in the modification of polypropylene was analyzed. X-ray diffraction analysis of the studied nanocomposites was carried out, the formation of β-PP was registered upon modification by Al2O3 nanoparticles. Photoluminescence spectra of nanocomposites were studied. It was found that the introduction of nanoparticles (except SiO2) does not lead to the formation of new luminescence bands in PP.

Research progress on the flame retardation and modification of polypropylene by montmorillonite

Montmorillonite can be used to achieve nano-dispersion level by forming peel or intercalation structure in polypropylene body, so as to improve the mechanical properties of the material. In addition, montmorillonite plays the role of nucleating agent during the crystallization of polypropylene, which improves the crystallization efficiency of polypropylene. After the organic modification of montmorillonite, the spacing between crystal surfaces can be enlarged to form organic montmorillonite, which makes the molecular chains of polypropylene more easily dispersed to the interlayer of organic montmorillonite, forming a dense surface layer in the process of thermal decomposition, so as to improve the thermal stability of polypropylene and enhance the flame retardant property of polypropylene. Many previous studies have shown that montmorillonite plays a significant role in improving the mechanical strength and crystallization effect of polypropylene, as well as the flame retardant properties of nanocomposites.

The ferrocene-bonding NH2-UIO-66 as an ion sieve to intercept polysulfides and screen Li+ for upgrading performance of lithium-sulfur batteries

Intercepting polysulfides and screening Li+ is one of the most effective methods to achieve high-performance lithium-sulfur (Li-S) batteries. This study focuses on the covalent anchoring of ferrocene into NH2-UIO-66 for the modification of polypropylene (PP) separator. The introduction of ferrocene enables the reduction of the pore size of NH2-UIO-66 from 5.1 Å to 3.9 Å, thereby blocking polysulfides anions and penetrating lithium cations at the molecular level, resulting in significant inhibition in the shuttle effect of polysulfides. The cell with this functional separator exhibits a high initial specific capacity of 1490 mA h g−1 with a capacity decay of 0.018 % after 1000 cycles at 2C. This work provides an effective method of separator modification for high-performance energy storage systems.

Hydrophilic surface modification of polypropylene by AC-DBD and NS-DBD

Dielectric barrier discharge (DBD) is a method to modify material surfaces by creating low-temperature plasma at atmospheric pressure. However, in comparison to low-pressure discharge, atmospheric DBD has the drawback of uneven surface treatment due to the ease of forming filamentary channels. This limitation hinders the widespread application of DBD technology in material surface modification. In this study, the surface of polypropylene (PP) was treated using high frequency alternating current (AC) and nanosecond (NS) pulsed argon DBDs to improve surface hydrophilicity. The changes of the PP surface hydrophilicity and the treatment uniformity were characterized by water contact angle (WCA) measurement. The relationships between the DBD characteristics, the treatment effect and the treatment uniformity of the PP surface were investigated using electrical and optical diagnostic techniques. The PP material surfaces before and after plasma treatments were evaluated by the physical morphology and chemical composition measurements to examine the influence of DBD on the treatment effect and uniformity on the PP material surface. The findings show that the modification by AC-DBD reduces the WCA of PP material surface by 40°∼50° and exhibits a variance of 1.77, indicating an improvement in hydrophilicity to some extent. Furthermore, the modification by NS-DBD further decreases the WCA of PP material surface, reducing the variance to 1.14. Compared with AC-DBD, NS-DBD has a better uniformity, a higher concentration of active particles in plasma, a greater surface roughness of PP material after treatment, a better hydrophilicity and a more uniform effect with less energy consumption. The results are meaningful to improve the application of DBD in material surface modification and optimize the power source election and operation parameters.

Radiation resistance of polypropylene modified with nanoparticles of oxide compounds

The results of studies of optical properties in UV, visible and IR spectral regions, and radiation resistance of nanocomposites based on polypropylene modified with nanoparticles of oxide compounds (ZrO2, Al2O3, SiO2, MgO, TiO2, ZnO) are presented. Diffuse reflectance spectra were recorded under 2 ∙ 10−6 torr vacuum before and after electron irradiation (in situ, Е = 30 keV, F = 2 ∙ 1016 cm−2). According to research findings, modification of polypropylene with nanoparticles leads to an increase in radiation resistance, which depends on the structure of the nanopowders, their size and specific surface area. The SiO2 nanopowder, characterized by its amorphous nature, the largest specific surface area, and the smallest particle size, stands as the most effective modifier for enhancing radiation resistance. The IR-Fourier spectra of electron-irradiated samples are similar to the original spectra. A slight decrease in transmission across all characteristic bands compared to the non-irradiated samples indicates minor structural changes as a result of irradiation.

Sorption Capabilities of Polypropylene/Modified Polypropylene Fibers

The aim of this paper is to present the influence of the modification of polypropylene (PP) fibers on the sorption capabilities of the fibers. The physical modification of the PP fibers was made with inorganic nanoadditives in the mass, with a view to improving the properties of silicate composites used in the construction industry. The compositions of the modified PP fibers using two different nanoadditives were based on previous work, as well as the work presented in this paper. The prepared modified PP fibers were compared with pure PP fibers, and their mechanical and thermomechanical properties were evaluated. Another task of this work was to evaluate and compare the sorption capabilities of these fibers without the preparation of concrete blocks. Therefore, the Washburn method was used. However, the obtained results led us to the conclusion that the given method points to the excellent transport properties of PP fibers if such properties are used to evaluate the sorption of the fibers. However, the sorption of the prepared modified fibers could be associated with the nanoadditives used, which have a higher water sorption capacity compared to pure PP fibers, and this could also ensure the higher adhesion of the modified PP fibers with inorganic additives to the cement matrix compared to the adhesion of the hydrophobic PP fibers.

Upcycling of Polypropylene Wastes via Catalytically C−H Modification with Polar Olefins

AbstractWhile polypropylene (PP) is one of the most widely used polyolefin materials, its post‐functionalization has been a continuously researched topic in the polymer field since it could significantly improve physical and chemical properties by introducing polar groups, beneficial for development of the next generation of polyolefin materials. In this work, we describe the development of a visible‐light promoted, environmentally friendly iron‐catalyzed strategy and establishing of the reaction scope for C−H alkylated modification of polypropylene. Under our conditions, various polypropylenes could be functionalized with diverse polar alkenes with good levels of functionalization (LOF). The properties of the resulting polymers were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tensile testing. Polypropylene wastes could also be upcycled. While the incorporation of the polyglycol groups enhanced hydrophilicity, the installation of the ester groups increased the miscibility with other polymers by acting as a compatibilizer for polystyrene and polyethylene.

Dopamine-Assisted Modification of Polypropylene Film to Attain Hydrophilic Mineral-Rich Surfaces.

The presented study focuses on the modification of polypropylene (PP) film with tetraethyl orthosilicate (TEOS) under heterogeneous conditions via polydopamine/polyethylene imine (PDA/PEI) chemistry using a facile dip-coating procedure to attain hydrophilic mineral-rich surfaces. Thus, the resulting PP-based films were further immersed in ion-rich simulated body fluid (SBF) to deposit Ca-based minerals onto the film's surfaces efficiently. In addition, the chemical reaction mechanism on PP film was proposed, and mineralisation potential inspected by determination of functional groups of deposits, zeta potential, hydrophilicity and surface morphology/topography using Fourier transform infrared (FTIR) spectroscopy, streaming potential, water contact angle (WCA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The obtained results show the improved wettability of samples on account of PDA inclusion (WCA was reduced from 103° for pure PP film to 28° for PDA-modified film), as well as the presence of functional groups, due to the PDA/PEI/TEOS surface functionalisation, increased the ability of minerals to nucleate on the PP film's surface when it was exposed to an SBF medium. Moreover, the higher surface roughness due to the silica coatings influenced the enhanced anchoring and attachment of calcium phosphate (CaP), revealing the potential of such a facile approach to modify the chemically inert PP films, being of particular interest in different fields, including regenerative medicine.

Surface modification of polypropylene by grafting films for active food packaging

Surface modification of polypropylene by grafting films for active food packaging

Simulation of the processes of plasma modification and vacuum metallization of polymer materials by the method of molecular dynamics

The article presents the results of the development of molecular dynamics models of modifications of polypropylene (PP) material in the plasma of a radio-frequency (RF) discharge and a copper coating deposit by magnetron sputtering on the surface of a polyethylene (PE) material. The model of the RF plasma modification process describes changes in the surface layers of the PP material upon interaction with low-energy plasma ions: the nature of the breaking of covalent bonds in macromolecules, the chemical composition of sputtered particles, and changes in the ordering of the supramolecular structure. The model of the vacuum metallization process describes the processes of the introduction of metal atoms into the polymer structure, the change in the conformation of macromolecules, the formation of macroradicals with uncompensated chemical bonds, and the formation of an interfacial layer between the polymer and the metal coating.

Study of the surface properties of polypropylene by enzyme treatment

Surface modification of polypropylene is performed in this work by enzyme-catalyzed post-processing strategy. The polyDOPA was synthesized by in-situ polymerization in the present of laccase and deposited on the polypropylene surface. The effect of various process variables namely processing step, pH, time, and temperature is studied at various levels. The results show that one-bath and one-step method is the optimal mode. Various functional groups incorporated to the polymer surface are confirmed by attenuated total reflectance-Fourier-transform infrared spectroscopy. The effect of process variables on surface morphology of polymers is evaluated by scanning electron microscopy, revealing that the surface of the polypropylene is covered with thin burrs, and these are regarded as polyDOPA adhered after treatment. Furthermore, the electrostatic charge decay time and contact angle as well as capillary wetting measurements of the modified polypropylene are 0.61 s and 75.33°, respectively, indicating its fine anti-static electricity and better wettability. Besides, this material shows dark gray colors and exhibits excellent ultraviolet-resistance performance. Interestingly, the modification process nearly has no influences on the mechanical property.

Different Radial Modification Profiles Observed on APPJ-Treated Polypropylene Surfaces according to the Distance between Plasma Outlet and Target.

The plasma jet transfer technique relies on a conductive wire at floating potential, which, upon entering in contact with a primary discharge, is capable of igniting a small plasma plume at the distal end of a long flexible plastic tube. In this work, two different long tube configurations were employed for the surface modification of polypropylene (PP) samples using argon as the working gas. One of the jet configurations has a thin copper (Cu) wire, which was installed inside the long tube. In the other configuration, the floating electrode is a metallic mesh placed between two plastic tubes in a coaxial arrangement. In the first case, the tip of the Cu wire is in direct contact with the working gas at the plasma outlet, whereas, in the second, the inner plastic tube provides an additional dielectric barrier that prevents the conductor from being in contact with the gas. Water contact angle (WCA) measurements on treated PP samples revealed that different surface modification radial profiles are formed when the distance (d) between the plasma outlet and target is changed. Moreover, it was found that the highest WCA reduction does not always occur at the point where the plasma impinges the surface of the material, especially when the d value is small. Through X-ray photoelectron spectroscopy (XPS) analysis, it was confirmed that the WCA values are directly linked to the oxygen-functional groups formed on the PP surfaces after the plasma treatment. An analysis of the WCA measurements along the surface, as well as their temporal evolution, together with the XPS data, suggest that, when the treatment is performed at small d values, the plasma jet removes some functional groups at the point where the plasma hits the surface, thus leading to peculiar WCA profiles.

Effect of multi‐walled carbon nanotube localization on toughening mechanism and electrical properties of compatibilized PP/EOC immiscible blend

AbstractToughness modification of polypropylene (PP), a widely used polymer in industry, is an important factor in overcoming mechanical limitations and extending its scope of application. In the present work, we utilized a combination of nanoparticle and elastomer techniques to enhance the toughness of PP. Accordingly, the nanocomposite blends, including PP, ethylene octene copolymer (EOC), and multi‐walled carbon nanotubes (MWCNTs), were prepared through three different feeding methods (direct, sequential, and masterbatch). The results demonstrated that the different feeding methods significantly affect the localization and dispersion degree of the MWCNTs, and hence, toughness modification. The results also showed that the sequential is the most effective method to prepare the nanocomposites with the reinforced fracture toughness so that the addition of 2 phr MWCNTs to the PP/EOC blend leads to a high impact strength (=351.61 J/m). Because in this feeding method, most of the highly dispersed MWCNTs can be selectively located in the EOC particles as well as the interface, which can not only intensify the interfacial interactions between the two phases but also help the stress transfer and superposition of stress fields. Moreover, it was shown that in the sequential method, the MWCNTs could facilitate the creation of electrically conductive pathways as a result of nanoparticle bridging and the formation of an interconnected percolating network, therefore increasing the electrical properties.

UV Photoinitiated Temperature-Sensitive Modification of Polypropylene Grafted with Poly(N-isopropylacrylamide)

UV Photoinitiated Temperature-Sensitive Modification of Polypropylene Grafted with Poly(N-isopropylacrylamide)

Hydrophilic cloth by surface modification of polypropylene fabrics with mineral particles

AbstractDifferent surface modifications of polypropylene non‐woven fabric (NWF) by using mineral particles are proposed to increase fabric hydrophilicity. Particles from a zeolitized vitreous breccia are selected as an economic mineral having high water absorption capacity. The efficacy of each methodology concerning particle inclusion on and within NWF is studied with different techniques. Scanning electron microscopy and X‐ray diffraction are used to analyze particle presence and coverage. Particle concentration on modified‐NWF is determined by using thermogravimetric analysis. The selection of the surface modification methodology is done considering the particle inclusion efficacy and its scalability to be directly used during NWF fabrication. Particle inclusion on the heat softened NWF followed by the removal of non‐adhered particles is chosen as the selected surface modification methodology to increase NWF hydrophilicity. To guarantee the no‐particle detachment during the use of modified‐NMF, specific assays are performed simulating extreme conditions such handling under water. After these assays, modified‐NWFs have a minimum water absorption capacity of 5.8 g/cm2. It means that 0.25 m2 of modified‐NWF has at least similar absorption capacity than 5 g of silica gel. These modified‐NWFs, obtained from an easy process during NWF fabrication, favor the beneficiation of the raw zeolitized vitreous breccia, leading to a new hydrophilic cloth.

Fabrication and Mechanical Properties of High-Durability Polypropylene Composites via Reutilization of SiO2 In-Situ-Synthesized Waste Printed Circuit Board Powder.

This paper focuses on the characterization of the physico-chemical properties, surface modification, residual copper content and in situ hybrid inorganic particle modification of polypropylene (PP) composites reinforced by waste printed circuit board powder (WPCBP). A series of WPCBP/SiO2 hybrids (TSW) were prepared by a sol–gel method at different pH values. Characterization results revealed the in situ generation of SiO2 on the surface of WPCBP, and showed that with an increase in pH value, the size of SiO2 particles increased gradually and the copper content decreased in the TSW powder. The mechanical properties, oxidation induction time (OIT) and thermal properties of PP composites were improved by reinforcement with TSW, which might be ascribed to the formation of serrated interfaces. This work not only develops a powerful method to enhance the properties of PP/WPCBP composites, but also provides an environmentally sustainable approach to the high-added-value reutilization of WPCBP.

Polypropylene Graft Poly(methyl methacrylate) Graft Poly(N-vinylimidazole) as a Smart Material for pH-Controlled Drug Delivery.

Surface modification of polypropylene (PP) films was achieved using gamma-irradiation-induced grafting to provide an adequate surface capable of carrying glycopeptide antibiotics. The copolymer was obtained following a versatile two-step route; pristine PP was exposed to gamma rays and grafted with methyl methacrylate (MMA), and afterward, the film was grafted with N-vinylimidazole (NVI) by simultaneous irradiation. Characterization included Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and physicochemical analysis of swelling and contact angle. The new material (PP-g-MMA)-g-NVI was loaded with vancomycin to quantify the release by UV-vis spectrophotometry at different pH. The surface of (PP-g-MMA)-g-NVI exhibited pH-responsiveness and moderate hydrophilicity, which are suitable properties for controlled drug release.