Dispersed Polypropylene Research Articles

Fabrication and toughening mechanism of high toughness PP/SEBS/HDPE blends with core‐shell particles

AbstractAiming at obtaining high toughness polypropylene (PP) products, in this work, using high density polyethylene (HDPE) and styrene‐ethylene‐butylene‐stryrene (SEBS) as toughening agents, PP/SEBS/HDPE blends were successfully fabricated by melt‐blending method, and the microstructure, mechanical, thermodynamics, and rheological properties of the blends were investigated. The results revealed the core‐shell structure particles with HDPE as the core and SEBS as the shell were dispersed in PP in the PP/SEBS/HDPE blends. The core‐shell structure particles played good roles in toughening PP matrix, and the PP/SEBS/HDPE blends underwent brittle‐tough transition at 15 wt% SEBS and 5 wt% HDPE. The impact toughness of PP/SEBS/HDPE blends with 15 wt% SEBS and 15 wt% HDPE reached 60.1 kJ/m2, which was almost 1441.0% that of pure PP. The formation of core‐shell particles in the system led to an increase in the degree of chain entanglement between the dispersed phase and PP, which enhanced the interfacial adhesion. In addition, based on the experimental results, the relationship between the viscosity and the material toughness was proposed, revealing the brittle‐ductile transition behavior and the toughening mechanism.

A green strategy to recycle the waste PP melt-blown materials: From 2D to 3D construction

The demand for polypropylene (PP) melt-blown materials has dramatically increased due to the COVID-19 pandemic. It has caused serious environmental problems because of the lack of effective treatment for the waste PP melt-blown materials. In this study, we propose a green and sustainable recycling method to create PP sponges from waste PP melt-blown material for oil spill cleaning by freeze-drying and thermal treatment techniques. The recycling method is simple and without secondary pollution to the environment. The developed recycling method successfully transforms 2D laminar dispersed PP microfibers into elastic sponges with a 3D porous structure, providing the material with good mechanical properties and promotes its potential application in the field of oil spill cleaning. The morphology structure, thermal properties, mechanical properties, and oil absorption properties are tested and characterized. The PP sponges with a three-dimensional porous network structure show an exceedingly low density of >0.014 g/cm3, a high porosity of <98.77 %, and a high water contact angle range of 130.4–139.9°. Moreover, the PP sponges own a good absorption capacity of <47.61 g/g for different oil and solvents. In particular, the compressive modulus of the PP sponges is 33.59–201.21 kPa, which is higher than that of most other fiber-based porous materials, indicating that the PP sponges have better durability under the same force. The excellent comprehensive performance of the PP sponges demonstrates the method developed in this study has large application potential in the field of the recycle of waste PP melt-blown materials.

Enhanced mechanical and dynamic mechanical properties of polymer nanocomposites containing carbon nanotubes decorated with barium titanate

This study presents functionalized carbon nanotubes (CNTs) decorated with functionalized barium titanate (BT) (denoted as BT@CNTs) via hydrothermal and self-assembly methods to improve dispersion in polypropylene (PP) matrix with enhanced thermal, mechanical, and thermomechanical properties. The CNTs, BT, and BT@CNTs with the addition of polypropylene maleic anhydride (PPMA) compatibilizer were used in the fabrication of the PP based nanocomposites for this study via solution mixing and melt compounding. FTIR, TEM, and SEM analyses, respectively revealed that the nanoparticles were successfully functionalized, CNTs decorated with BT, and well dispersion in the PP matrix. PP/BT@CNTs-based nanocomposite showed optimal tensile strength, modulus, heat deflection, and thermal stability of about 16.8%, 26.5%, 20.1%, and 30oC higher than that obtained for the pure PP. These properties were also respectively 10.6%, 17.6%, 19.0%, and 5.0oC higher than PP/3CNTs nanocomposite when compared to PP/3BT@CNTs. The PP/BT@CNTs based nanocomposites also revealed enhanced dynamic mechanical properties. The better performance in the measured properties of PP/BT@CNTs compared to pure PP and PP/CNTs were attributed to their uniform microstructures, effective interlocking of the PP matrix due to the presence of BT on CNTs surfaces.

Carbon fiber versus glass fiber reinforcements: A novel, true comparison in thermoplastics

AbstractCarbon fiber and glass fiber are two dominating reinforcements for polymer composites. Fiber‐reinforced thermoplastics are widely used in many applications. It has a higher growth rate than thermoset composites due to ease in processing and recyclability. Glass fiber has been on the market for 80 years and carbon fiber over 50 years. There are hundreds, if not thousands, of research paper to compare the performance of the two fibers and hybrid. All the studies are from commercially available products. In all those cases, these two fibers are non‐comparable. They have different fiber diameter, size and sizing content, chop length and chopping process. Taiwan Glass Industries, Corp. has cordially provided two experimental chopped strands that match the characteristics of chopped carbon fibers. The first one is for nylon reinforcement and the second one is for polypropylene. Now the glass fiber and carbon fiber have the same fiber diameter (7 microns), same size and sizing content (1%), and same chop length (6 mm). Most importantly, they are produced in identical way (off‐line chop). The only difference between two fibers is silane on glass surface. This is the first of this kind of study. It gives a true comparison of two fibers with identical characteristics. As expected, fiber diameter has the biggest influence in mechanical properties among all fiber characteristics. For nylon, the difference between 7 micron and 10 micron glass fiber is small in tensile and flexural strength. It has bigger difference in impact strength. For polypropylene reinforcement, the fiber diameter of standard polypropylene dispersion (PP) glass fiber is 13 microns; almost double that of carbon fiber. Seven‐micron PP glass actually outperforms PP carbon fiber in composite strengths.

Impact of reinforcement on shrinkage in the concrete floors of a residential building

Abstract The type of floor in a building object results from the serviceability requirements, technical possibilities, and costs of its implementation. Concrete screeds constituting the structural layer of the floor can be made without reinforcement, with dispersed reinforcement, or reinforced with meshes of various materials. Due to the large surface dimensions, concrete screeds are susceptible to scratches as a result of occurring strains, service loads and unevenness of the floor. There are detailed recommendations on how to make floors, and on the materials used. However, the conditions in which floors are made often differ from those recommended. The article presents the results of measured strains on the surfaces of three screeds constituting the floor layer in a residential building. The screeds, which were made in identical environmental conditions, differed in the type of reinforcement used: steel mesh, dispersed polypropylene fibres, fibreglass mesh. In addition, strain measurements were carried out on concrete and fibre-reinforced concrete specimens made of the mix used to make the screeds. The results allowed the assessment of the effectiveness of the reinforcement used, the impact of environmental conditions on the values, and the analysis of differences in the course of strains in real elements and the specimens.

Optimization and assessment of MWCNT dispersion in polypropylene nanocomposite films

Functionalized carbon nanotubes dispersion in polypropylene is optimized and investigated using thresholding based image segmentation. Carbon nanotubes polypropylene films are developed using solution casting method and MWCNT dispersion is optimized upto 1% MWCNT concentration. Dispersion state is investigated by thresholding based image segmentation and agglomeration estimation method applied on scanning electron microscopy (SEM) images. K-means clustering algorithm is applied further to validate the thresholding algorithm by calculating the MWCNT weight % in processed SEM images. It is found that the proposed clustering algorithm can detect MWCNT concentration significantly upto 1%. To further validate the dispersion studies, developed nanocomposite films are used to fabricate the dragonfly inspired artificial flapping wings. The natural frequency was found maximum for 1% MWCNT-COOH-PP wing at 52.27 Hz.

The Recognition of the Micro-Events in Cement Composites and the Identification of the Destruction Process Using Acoustic Emission and Sound Spectrum.

This paper presents the recognition of micro-events and their concentration in quasi-brittle cement composites and the identification of the destruction process based on acoustic emission and sound spectrum. The tests were conducted on a quasi-brittle composite of a cement paste reinforced with a high volume of dispersed polypropylene fibers. The possibility of identifying the destruction process based on acoustic emission and sound spectrum was confirmed. This paper focused on the identification of micro-events using the 3D spectrum. It was shown that the identification of the concentration of micro-events precedes the occurrence of critical crack fcr, ending the Hooke’s law range. The ability to recognize this phenomenon with the use of the 3D spectrum makes it possible to predict the structure destruction process and subsequently to assess the structure destruction (micro and macro-cracks) and the reinforcement destruction (pull-off, breaking). It was confirmed that the three-dimensional spectrum provided additional information, enabling a better recognition of micro and macro-changes in the structure of the samples based on the analysis of sound intensity, amplitudes, and frequencies.

Nanofillers-induced modifications in microstructure and properties of PBAT/PP blend: Enhanced rigidity, heat resistance, and electrical conductivity

Carbon nanotube (CNT) and organoclay (15A) were introduced separately and simultaneously into the poly(butylene adipate-co-terephthalate) (PBAT)/polypropylene (PP) blend to fabricate PBAT-based nanocomposites with maleated PP played as a compatibilizer. SEM and TEM analyses confirmed the CNT and 15A were predominantly distributed in the PBAT matrix and in the dispersed PP phase, respectively. Addition of sole CNT or 15A developed a quasi-co-continuous PBAT-PP morphology. CNT assisted the nucleation for both PBAT and PP crystallization, while 15A facilitated the nucleation for PP only. The heat distortion temperature of the blend increased 20 °C at 3-phr CNT loading. Adding hybrid fillers of CNT and 15A improved Young's modulus and flexural modulus by up to 35% and 144%, respectively, compared with those of the parent blend. The impact strength increased by up to 33% after 2-phr CNT loading. The electrical resistivity of the blend reduced by more than 9 orders at 3-phr CNT loading.

Morphology, Rheology and Crystallization in Relation to the Viscosity Ratio of Polystyrene/Polypropylene Polymer Blends.

Microfibrillar and droplet morphology of polypropylene (PP) phase dispersed in polypropylene (PS) was fabricated by using melt-extrusion. This morphology was obtained by introducing isotactic PP (20 wt.%) with different viscosity in the PS matrix (80 wt.%). Furthermore, the rheological properties of the blend investigated as a function of the viscosity ratio K. The variations in blend morphology were related to crystallization, melting properties, and viscoelasticity. The blends with K >> 1 develop a fine morphology with PP microfibrils along the flow direction, while diameters of the dispersed PP droplets gradually increase with lower values of K = 1, or K << 1. Crystallinity of the prepared blends significantly decreases compared to neat PP, while the microfibrillar morphology induces homogeneous crystallization with small crystallites. This is reflected in a decrease of the crystallization temperature, small loss in the crystallinity, and lower melting temperature of the PS80/PP20 blend compared to neat PP. The storage moduli, loss moduli, and complex viscosity are highest for the microfibrillar morphology that presents retarded relaxation. The rheological properties are dominated by the dispersed phase (K > 1), or matrix (K < 1). The variation in blend properties with microfibrillar morphology can be clearly distinguished from heterogeneous blends containing PP droplets, providing an efficient tool to create a binary blend with unique properties.

Compressive strength of lightweight expanded polystyrene basalt fiber concrete

The ability of concrete to give a lower weight and retain good properties for strength is very important concrete structures. Lightweight concrete is known for its brittleness hence the strengthening of the concrete with dispersed chopped fiber is necessary. The addition of dispersed chopped fiber in polystyrene concrete to check the effect of the fiber this concrete the main objective of this paper. The experimental method of research was used in this research paper after a proper review of previous works by other researchers were done. 42 grams of fiber were added in the concrete mix of each composition. The results of this research show a noticeable effect of fiber in the lightweight expanded polystyrene concrete. The concrete without fiber showed the best compressive strength followed by the concrete with dispersed polypropylene fiber.

Compatibilization of natural rubber–polypropylene thermoplastic elastomer blend

The effects of the addition of epoxidized natural rubber/maleic anhydride-grafted polypropylene blend as a compatibilizing agent (CA) on the properties of natural rubber (NR)/polypropylene (PP) thermoplastic elastomer blend were studied. The blends were prepared in the molten state at 180°C using a Brabender Plasticorder at a rotor speed of 60 r min−1. Evidence of compatibilization was obtained from the Brabender plastograms and from the mechanical properties results as well as the morphological analysis. It was found that the addition of the CA at different contents resulted in an increase of the tensile strength and Young’s modulus and a decrease of the elongation at break. It was also found that the melting temperature remained unchanged, the % crystallinity decreased, but the thermal stability was not affected. The morphology revealed a more homogeneous distribution of the dispersed PP phase for the CA-containing systems compared to the control NR/PP blend. These effects were attributed to the interactions that developed with the blend constituents through the functional groups of the CA.

Organic modification of Mo-decorated MgAl layered double hydroxide for polymer flame retardancy

A novel stearic-pillared MgAl layered double hydroxide (S-Mo/LDH) containing MoOx nanoparticles was successfully prepared by calcination-reconstruction, where MoOx nanoparticles were decorated onto the surface of the S-Mo/LDH by reducing the MoO42−-pillared LDH precursor (Mo-LDH). The microstructures, bonding states and surface properties were investigated by XRD, SEM, FT-IR, BET/BJH, WAC and TG-DTG, which confirmed that the interlayer MoO42− anion was grafted onto the brucite sheets to form MoOx nanoparticles during the calcination process of the Mo-LDH, and stearic anions were intercalated into the interlayers of the S-Mo/LDH. The performances of the flame-retardancy were improved by combining these properties of the individual materials of stearic, parent LDH and MoOx nanoparticles. In comparison to the Mo-LDH, the S-Mo/LDH demonstrated a more homogeneous dispersion in polypropylene (PP) matrix due to surface hydrophobicity. The incorporation of the S-Mo/LDH filter at 20 g∙100 g−1 loading provided an excellent fire resistance towards PP matrix, giving the high limited oxygen index (28.6%), vertical burning UL94 (V-0) and reduced total heat release (71.6% reduction in PHRR relative to neat PP). These remarkable properties indicated that the approach to improve flame retardancy of PP was a cost-effective, feasible and highly effective way.

Identification of the Destruction Process in Quasi Brittle Concrete with Dispersed Fibers Based on Acoustic Emission and Sound Spectrum.

The paper presents the identification of the destruction process in a quasi-brittle composite based on acoustic emission and the sound spectrum. The tests were conducted on a quasi-brittle composite. The sample was made from ordinary concrete with dispersed polypropylene fibers. The possibility of identifying the destruction process based on the acoustic emission and sound spectrum was confirmed and the ability to identify the destruction process was demonstrated. It was noted that in order to recognize the failure mechanisms accurately, it is necessary to first identify them separately. Three- and two-dimensional spectra were used to identify the destruction process. The three-dimensional spectrum provides additional information, enabling a better recognition of changes in the structure of the samples on the basis of the analysis of sound intensity, amplitudes, and frequencies. The paper shows the possibility of constructing quasi-brittle composites to limit the risk of catastrophic destruction processes and the possibility of identifying those processes with the use of acoustic emission at different stages of destruction.

Influence of the nano TiO2 dispersion procedure on fresh and hardened rendering mortar properties

Abstract This study was carried out to evaluate the influence of n-TiO2 dispersion on fresh and hardened rendering mortar properties. Five compositions were evaluated with dispersed polypropylene microfibers (PPMF): a reference, without n-TiO2 addition, and four using two commercial samples of n-TiO2, evaluated in two dispersion conditions. Although the materials were the same in all formulations, the water content was modified to maintain the same mortar consistency as determined by flow table results. The fresh properties of the mortars were determined by means of squeeze flow and air-entrainment tests, while hardened properties were evaluated by capillary water absorption, air-permeability, dynamic elastic modulus, drying shrinkage, split tensile strength according to the Brazilian test, and porosity by the Archimedes immersion method. The results obtained have shown that the fresh and hardened mortar properties were affected by the dispersion procedure and the properties of the n-TiO2 samples, indicating that the addition of n-TiO2 in a dispersed form was more effective to control fresh and hardened mortar properties. On the other hand, drying shrinkage results are not influenced by the dispersion procedure but as of the characteristics of n-TiO2.

Modification of polypropylene fibres with cationic polypropylene dispersion for improved dyeability

Polypropylene (PP) fibres are important hydrophobic fibres which are used in the production of functional textiles such as sports textiles. The absence of functional groups and low polarity make PP fibres difficult to dye, thus mass coloration during fibre extrusion is the major technique applied today. However, the disadvantage of mass coloration is the low flexibility and the demand to produce high volumes. A new method to modify the surface of PP fibres utilises the deposition and thermal fixation of cationic PP dispersion. Through padding and thermal fixation of a cationic PP dispersion, dyeable 100% PP fibres can be obtained. The effects of fixation temperature, and of the amount of dispersion used on the modified fibres were studied using Fourier Transform‐infrared spectroscopy, laser scanning microscopy, dyeing experiments with CI Acid Red 151, and by determining selected fastness properties. The results indicate the potential of this new method to produce surface‐modified 100% PP fibres, which can be dyed in conventional acid‐dyeing processes and therefore used in fibre blends, for example in combination with wool.

Morphological, Rheological, and Mechanical Properties of Polyamide 6/Polypropylene Blends Compatibilized by Electron-Beam Irradiation in the Presence of a Reactive Agent.

An immiscible polyamide 6 (PA6)/polypropylene (PP) blend was compatibilized by electron-beam irradiation in the presence of reactive agent. Glycidyl methacrylate (GMA) was chosen as a reactive agent for interfacial cross-copolymerization between dispersed PP and continuous PA6 phases initiated by electron-beam irradiation. The PA6/PP (80/20) mixture containing GMA was prepared using a twin-screw extruder, and then exposed to an electron-beam at various doses at room temperature to produce compatibilized PA6/PP blends. The morphological, rheological, and mechanical properties of blends produced were investigated. Morphology analysis revealed that the diameter of PP particles dispersed in PA6 matrix was decreased with increased irradiation dose and interfacial adhesion increased due to high surface area of treated PP particles. Complex viscosities (η*) and storage moduli (G’) of blends increased with increasing irradiation dose and were higher than those of PA6 and PP. The complex viscosity of the blend irradiated at 200 kGy was 64 and 8 times higher than PA6 and PP, respectively. The elongation at break of blend irradiated less than 100 kGy was about twice that of PA6. Electron beam treatment improved the compatibility at the interface between PA6 and PP matrix in the presence of GMA.

Interface modification of compatibilized polyethylene terephthalate/polypropylene blends: Effect of compatibilization on thermomechanical properties and thermal stability

Polyethylene terephthalate (PET) and polypropylene (PP) are incompatible thermoplastics because of differences in chemical structure and polarity, hence their blends possess inferior mechanical and thermal properties. Compatibilization with a suitable block/graft copolymer is one way to improve the mechanical and thermal properties of the PET/PP blend. In this study, the toughness, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA) of PET/PP blends were investigated as a function of different content of styrene-ethylene-butylene-styrene-g-maleic anhydride (SEBS-g-MAH) compatibilizer. PET, PP, and SEBS-g-MAH were melt-blended in a single step using the counter rotating twin screw extruder with compatibilizer concentrations of 0, 5, 10, and 15 phr, respectively. The impact strength of compatibilized blend with 10 phr SEBS-g-MAH increased by 300% compared to the uncompatibilized blend. Scanning electron microscope (SEM) micrographs show that the addition of 10 phr SEBS-g-MAH compatibilizer into the PET/PP blends decreased the particle size of the dispersed PP phase to the minimum level. The improvement of the storage modulus and the decrease in the glass transition temperature of the PET phase indicated an interaction among the blend components. Thermal stability of the PET/PP blends was significantly improved because of the addition of SEBS-g-MAH. J. VINYL ADDIT. TECHNOL., 23:45–54, 2017. © 2015 Society of Plastics Engineers

Effect of Compatibilizer Content on the Mechanical and Morphological Properties of PET/PP (70/30) Blends

This work investigates the effect of compatibilizer concentration on the mechanical properties of compatibilized polyethylene terephthalate (PET) /polypropylene (PP) blends. A blend containing 70 % (wt) PET, 30 % (wt) PP and 5 - 15 phr compatibilizers were compounded using counter rotating twin screw extruder and fabricated into standard test samples using injection molding. The compatibilizer used is styrene-ethylene-butylene-styrene grafted maleic anhydride triblock copolymer (SEBS-g-MAH). Morphological studies show that the particle size of the dispersed PP phase is dependent on the compatibilizer content up to 10 phr. Impact strength and elongation at break showed maximum values with the addition of 10 phr SEBS-g-MAH and a corresponding decrease in flexural and young’s moduli; and strengths.. Overall the mechanical properties of PET/PP blends depend on the control of the morphology of the blend and can be achieved by effective compatibilization using 10 phr SEBS-g-MAH.

Effect of surface modification of calcium carbonate nanoparticles on their dispersion in the polypropylene matrix using stearic acid

In this study, effects of surface modification of calcium carbonate (CaCO3) nanoparticles with a single-layer of stearic acid were investigated on dispersion in polypropylene (PP) matrix. Two kinds of CaCO3 nanoparticles (monolayer-coated and uncoated) were used to investigate this effect. All combi- nations were mixed in a co-rotating twin screw extruder and then were injection molded. After breaking the injection molded parts in liquid nitrogen, effect of surface modification of nanoparticles on their disper- sion in the PP matrix was investigated using a field emission scanning electron microscope (FESEM). The results showed good agreement between the measurements made with the TGA analysis and the existing theories. The surface modification of calcium carbonate nanoparticles using a single layer of stearic acid also had an effective influence on improving distribution and dispersion of nanoparticles in the PP matrix.

Alkali-Activated Matrix Based on Metakaoline with Lightweight Aggregate

The paper focuses on design and verification of mix-design of lightweight concrete with alkali-activated matrix with lightweight aggregate Liapor. Alkali-activated matrix was designed on the basis of ground metakaoline and micronized limestone. Mixes of concrete with alkali-activated matrix and lightweight porous aggregate Liapor of size fraction 8 mm were designed and their rheological and physico-mechanical properties were tested. To reduce shrinkage and to increase resistance to high temperatures, dispersed polypropylene fiber reinforcement was used and testing specimens made from this concrete with alkali-activated matrix were exposed to thermal load and tested.