Filled Polypropylene Composites Research Articles

Analysing and predicting dielectric properties of bamboo fiber filled polypropylene composites using artificial neural network

Analysing and predicting dielectric properties of bamboo fiber filled polypropylene composites using artificial neural network

Mechanical and environmental evaluation of ground calcium carbonate (CaCO3) filled polypropylene composites as a sustainable alternative to virgin polypropylene

Polypropylene (PP) has raised environmental concerns particularly for its depletion of fossil-fuels and contribution to climate change. To lower environmental impacts, PP can be combined with biobased fillers such as calcium carbonate (CaCO3). The mechanical and environmental properties of CaCO3 filled PP have not yet been explored in depth. Therefore, this study examines the aesthetic, tensile, flexural, impact, and environmental (via life cycle assessment) properties of injection moulded CaCO3 filled PP with filler content ranging from 0% to 40% at 5% increments. As filler percentage increased, yield strength decreased (0% CaCO3: 17.68 MPa, 40% CaCO3: 12.73 MPa), but young's modulus, flexural modulus, and impact strength increased (respectively 69%, 51%, and 35% greater than pure PP). Flexural strength increased initially at 5% CaCO3 but then declined as more filler was added. A yellowish hue was observed within all blends which growed stronger with more filler. The addition of CaCO3 reduced the environmental impact for all 11 impact categories. For every 5% of CaCO3 added, the material's global warming potential (GWP) decreased by 100g CO2 eq. per functional unit (1000 cm3) of composite. Abiotic depletion of fossil fuels declined by 32% when 40% CaCO3 was added. In addition to this study, it would be beneficial to explore other factors that affect the properties of CaCO3 filled PP such as particle size, particle distribution, and binding additives.

Durability evaluation of mechanical and thermal properties of graphite–copper hybrid powder filled polypropylene composites

Abstract The sustainability of polymer composites in real time environments can be ensured by durability studies. This paper aims to evaluate the durability of mechanical and thermal properties of graphite (G) and copper (Cu) particle-filled polypropylene (PP) composites. Three types of composites, PP/G, PP/Cu, and PP/G/Cu, were prepared by melt compounding and compression molding. The compressive strength, microhardness, and thermal properties of the composites were tested after 2 and 90 days of storage under ambient conditions. The results showed a noticeable decrease in the compressive strength of the composites, reaching ∼60–70 % compared to that of the neat PP and showed a ductile-like fracture mode. A further decrease in the strength values of ∼90 % occurred when the composites were tested after 90 days and a brittle-like fracture mode was observed. The addition of G and Cu to PP improved its microhardness and a drastic decrease also appeared after 90 days compared to that of their counterparts tested after 2 days. DSC measurements showed that the melting temperature, T m, decreased and crystallization temperature, T c, increased indicating a better ability of the fillers for nucleation in PP and obstructing its crystal growth. The degree of crystallinity, X c, of PP in the composites decreased compared to that of the neat PP and it increased when tested after 90 days compared to that tested after 2 days.

Mechanical and Tribological Performance of Polypropylene/Tin Powder Composites

In this study, the effect of Tin powder filler content on the mechanical and tribological performance of Tin filled Polypropylene (PP) composites were investigated. Polypropylene composites were prepared in a Brabender kneading chamber. The melt was transferred to a laboratory hot press and compression molded into samples for tests. The mechanical performances of the polymer based composites were determined by tensile and notched izod impact tests. The tribological tests were carried out in dry condition using pin-on-disc at 0.5−1.5 m/s Sliding Speed (SS) and 10–30 N loads. The mechanical test results demonstrated that the incorporation of Tin powders increased the Tensile Strength (TS) (5.6%), tensile modulus (TM) (19.8%) and izod Impact Strength (IS) (41.8%) while decreased the Elongation at Break (EB) (80%) values of Tin powder filled PP composites. The Friction Coefficient (COF) and Specific Wear Rate (SWR) decreased with the increase in filler content. The COF of unfilled PP, PP-8% Tin powder, PP-16% Tin powder and PP-24% Tin powder composites decreased about 20%, 23.4%, 21.8% and 29.3% with the increase in applied load from 10 N to 30 N, respectively. The SWR of the Tin powder filled PP composites decreased by 91% compared to unfilled PP polymer at 1.5 m/s speed and 30 N load value.

Investigation of Mechanical and Microstructural Properties of Polyolefin Rubber and Glass Beads Filled Polypropylene Composites

In the automotive industry and many industries, parts are expected to meet certain requirements with regards to their tensile strength, stiffness, and high impact strength. For this reason, polypropylene homopolymer, which is a fragile polymer widely used in the automotive industry, is combined with additives to reduce its fragility. In this study, the mechanical and microstructural properties of polyolefin rubber and glass bead filled polypropylene composites have been investigated. Polypropylene (PP) was combined with polyolefin rubber (POE) and glass beads (GB) at different weight rates to create the composites and pure polypropylene was compared to the three prepared PP composites; 8% polyolefin rubber by weight, 8% glass bead by weight, and 8% polyolefin rubber and 8% glass bead by weight. The fracture surface examinations of the pure polypropylene (PP), and the polyolefin rubber added PP, glass bead added PP, and polyolefin rubber and glass bead added PP composites were carried out using Scanning Electron Microscopy (SEM). In addition, Energy Dispersive Spectroscopy (EDS) analysis was also performed for the characterization. It was observed that the tensile strength values of the PP composites (PP-8%POE, PP-8%GB, and PP-8%POE-8%GB) showed a slight decrease relative to the pure PP. When rigid glass beads were added to the pure PP polymer main matrix (8% by weight), the stiffness of the composite increased and the modulus of elasticity increased by approximately 8% relative to pure PP. In addition, it was observed that the % elongation at break values of the PP composites (PP-8%POE, PP-8%GB, and PP-8%POE-8%GB) increased significantly relative to the values for pure PP.

Reusability of autoclaved 3D printed polypropylene compared to a glass filled polypropylene composite

Health care waste can be a costly expenditure for facilities as specific disposal methods must be used to prevent the spread of pathogens. If more multi-use medical devices were available, it could potentially relieve some of this burden; however, sterilization between uses is important in preventing disease transmission. 3D printing has the ability to easily create custom medical devices at a low cost, but the majority of filaments utilized cannot survive steam sterilization. Polypropylene (PP) can withstand autoclave temperatures, but is difficult to print as it warps and shrinks during printing; however, a composite PP filament reduces these effects. Commercially available PP and glass filled PP (GFPP) filaments were successfully 3D printed into 30 × 30 × 30 mm cubes with no shrinking or warping and were autoclaved. The 134 °C autoclave temperature was too high as several cubes melted after two to three rounds, but both PP and GFPP cubes displayed minimal changes in mass and volume after one, four, seven, and ten rounds of autoclaving at 121 °C. GFPP cubes autoclaved zero, four, seven, and ten times had significantly smaller average compressive stress values compared to all PP groups, but the GFPP cubes autoclaved once were only less than PP cubes autoclaved zero, seven and ten times. GFPP cubes autoclaved zero, one, four, and seven times also deformed less indicating that the embedded glass fibers provided additional strength. While a single method was found that successfully printed PP and GFPP cubes that were able to survive up to ten rounds of autoclaving, future work should include further investigation into the mechanical properties and increasing the number of autoclave rounds.

Effect of carbonization temperature on properties of natural fiber and charcoal filled hybrid polymer composite

In this study, bamboo fiber filled polypropylene composites (BPCs) were prepared using bamboo and coconut shell charcoal as reinforcing fillers for enhancing the properties of composites. Bamboo and coconut shell biomass were carbonized at different carbonization temperatures (300, 400, 600, and 900OC); 1 h soaking time and at 5OC−min heating rates. The effect of carbonization temperature and charcoal content (0.5%, 1.0% and 1.5%) on mechanical, thermal and water absorption properties of BPCs has been investigated. The experimental results show that charcoal which is obtained at lower pyrolysis temperature (300OC and 400OC) improves the strength properties of BPCs, whereas, strength properties remains unaltered when charcoal prepared at elevated temperatures (600OC and 900OC) are added to BPCs. Compared to coconut shell charcoal (CSC) better mechanical properties were obtained through bamboo charcoal (BC). This has been attributed to flakes like appearance of BC, having pores present on their surfaces. The study also shows that addition of charcoal provides thermal stability to BPCs, particularly via charcoal prepared at elevated temperature (900OC). The optimum temperature for achieving sufficient hydrophobicity in BPCs is found to be 300OC and 600OC for BC and CSC, respectively.

Biodegradation kinetic modeling of pro-oxidant filled polypropylene composites under thermophilic composting conditions after abiotic treatment.

This work aims at modeling and characterizing the kinetics of biodegradation of polypropylene loaded with cobalt stearate as pro-oxidant after abiotic treatment. Eight films of these composites were prepared using different pro-oxidant loadings. These films were treated abiotically using accelerated weathering for 40 h, and biotically using aerobic composting as per ASTM D 5338. The experimental data were analyzed using an eight-parameter Komilis model containing a flat lag phase. The model formulations involved hydrolysis of primary solid carbon and its subsequent mineralization. The first step was rate controlling and it included hydrolysis of slowly (Cs), moderately (Cm), and readily (Cr) hydrolyzable carbon fractions in parallel. The model parameters were evaluated by means of nonlinear regression technique. The surface morphology of the films before and after the biodegradability test supported the biodegradation results. The model parameters and undegraded/hydrolyzable/mineralizable carbon evolutions involved moderately and readily hydrolyzable carbons but with the absence of slowly hydrolyzable carbon. These exhibit degradability in the range of 11.20-36.42% in 45 days. Biodegradability increases with progressive increase in pro-oxidant loading. The rate of degradation reaches maximum (0.322-0.897% per day) at around the 39th-12th day. For all the films, readily hydrolyzable carbon fractions and their hydrolysis rate constants (kr) are appreciably increased with increasing pro-oxidant loading. All the films show the presence of growth phase because of their high initial readily hydrolyzable carbon fractions. The SEM images after the abiotic and subsequently biotic treatments were progressively rougher. The methods presented here can be used for the design and control of other similar systems.

Preparation and characterization of Ni0.5Zn0.5Co0.2Fe1.8O4 filled polypropylene composites

This work discusses about the preparation and characterization of Ni0.5Zn0.5Co0.2Fe1.8O4 filled Poly Propylene Composites for microwave substrate applications. Phase pure Ni0.5Zn0.5Co0.2Fe1.8O4 filler composition is prepared through solid state ceramic route. Phase purity is confirmed by Powder X- ray diffraction analysis. Morphology and filler distribution of the composites are investigated by Scanning Electron Microscope analysis. Using Agilent 4294A Impedance Analyzer the dielectric and magnetic characterizations are done at low frequency region. Effective permeability and permittivity of the composites are compared with predicted values from different theoretical modeling approaches. Ni0.5Zn0.5Co0.2Fe1.8O4 filled PP composite have an effective dielectric constant of 6.75 and loss tangent of 0.006 at the optimum filler loading at 1 MHz. The composite also has magnetic permeability of 3.51 at the optimum filler loading. Relatively good dielectric constant, better relative permeability together with very low loss tangent make the Ni0.5Zn0.5Co0.2Fe1.8O4 filled PP Composites an excellent choice as Microwave substrate.

Influencing parameters on measurement accuracy in dynamic mechanical analysis of thermoplastic polymers and their composites

Long-term predictions of material properties such as stiffness and creep resistance are important in many engineering applications and require high reliability and accuracy. This is especially true for polymer materials and their composites as their viscoelastic nature results in time-dependent material behaviour and any measurement uncertainties or errors amplify in long-term predictions. To measure this behaviour at smallest loadings, Dynamic Mechanical Analysis (DMA) is frequently declared as an ideal method. However, the measurement accuracy and repeatability of this method is strongly influenced by (i) the testing fixture and corresponding loading mode, (ii) the sample preparation and (iii) the plotting scale to interpret the test results. In this study, relevant experimental parameters were found for DMA and a proper procedure was designed, which was then applied to measure the viscoelastic behaviour of a highly temperature and creep resistant thermoplastic polymer (polyethersulfone) and of a highly graphite filled polypropylene composite. In combination with finite element simulations and in-situ strain measurements by digital image correlation (DIC), the main influences on measurement accuracy of three-point-bending DMA were identified and subsequently used to determine measurement guidelines. Using these guidelines, DMA measurements allow quantitative determination of the viscoelastic response for rigid polymer and composite materials.

Evaluation of water repellency in bentonite filled polypropylene composites via physical and mechanical methods

With the advent of polymeric materials having dimensional stability, outdoor applications for polymer composites are increasing expeditiously. The employment of durable material in wet environments is the most effective means of water repellency. Silane modification was applied to bentonite clay for the donation of hydrophobicity on its surface. Surface functionalities of powder surfaces were confirmed by FTIR-ATR spectroscopy and SEM techniques. Polypropylene composities involving pristine and modified bentonite powders were produced in bulk and film forms at three different loading ratios. Water permeability of bulk and film samples was evaluated via water absorption test. In addition to water uptake values, optical microscopy was utilized in order to visualize the structural deterioration of composite samples after water immersion. Mechanical behaviours of composite materials before and after water absorption test were reported in order to analyze the effect of water aging. Based on the findings, in-depth discussions were performed by comparison with basic models postulated regarding migration of water molecules into polymer structure.

UV and thermal weathering of green composites: Comparing the effect of different agricultural waste as fillers

In general, agricultural waste (residue) is left to nature or employed as fuel material in houses. However, such use of agricultural waste adversely affects the environment. To reduce the negative impact of agricultural waste on the environment, it can be utilized as natural filler in thermoplastic composites owing to its cellulosic structure. This research aims to determine ultraviolet (UV) and thermal ageing of natural fiber reinforced composites to investigate their potential of using in outdoor applications. Therefore, five kinds of agricultural waste were employed as natural fillers for fabricating polypropylene (PP) based composites in current research. Sunflower seed husk (dakota and white type), pumpkin seed husk, pistachio shell and hazelnut shell were utilized as natural fillers. Tensile behaviour of natural flour filled PP composites was characterized by a brittle failure. Though the natural fillers reduced the tensile and impact strength of pure PP, the mechanical properties were still acceptable for some applications and lower cost of natural filled PP composites made them feasible. It was concluded that sunflower seed husk (dakota and white type), pumpkin seed husk, pistachio shell and hazelnut shell flour filled PP composites could compete with pure PP when flexural strength was taken into consideration. Thus, more environmentally friendly composites with good flexural strength were developed. It was found that the influence of UV and thermal ageing on mechanical properties was not detrimental. In general, dakota type sunflower seed husk flour reinforcement gave the best mechanical properties among the natural composites, thus indicating better stress transfer.

Evaluation of Mechanical and Thermal Properties of Artichoke Filled Polypropylene Composites: Influence of Wollastonite Hybridization

Today, plant-fiber-filled polymer composites are used in many applications because of their favorable properties such as low price, renewability, biodegradability and non-toxic characteristics. How...

Selected properties of mahogany wood flour filled polypropylene composites: The effect of maleic anhydride-grafted polypropylene (MAPP)

The aim of this study was to produce mahogany (Swietenia macrophylla) wood flour filled polypropylene (both recycled and virgin) composites and to determine the effects of maleic anhydride-grafted polypropylene (MAPP) on the interfacial compatibility, density, and other mechanical properties of the resulting composites. Approximately 40 wt% of mahogany wood flour, and 60 wt% of polypropylene, 3 wt% of MAPP, 1.5 wt% of zinc stearate, and 1.5 wt% of wax were used during composite manufacturing. Test specimens were manufactured using extrusion and injection molding processes. The flexural, tensile, impact, and hardness properties of all specimens were determined. Scanning electron microscopy was used to study the morphology and interfacial compatibility of the filler in prepared composites. The test results showed that MAPP use and the filler rates affected the density and mechanical properties of test specimens.

Analysis of Erosion Wear Behavior of LD Sludge Filled Polypropylene Composites Using RSM

In the current investigation, a large number of experimental data are created for a set of Linz-Donawitz (LD) sludge filled polypropylene composites by fabricating them through compression molding technique and by conducting different tests to find out their physical, mechanical and erosion wear behaviour under controlled laboratory conditions. The erosion wear trials are carried out on the fabricated polypropylene-LD sludge composite samples as per ASTM standard using response surface methodology (RSM). This study discloses that the impact velocity and the filler content are the most predominant factors influencing the erosion rate of the composite. Mechanical characterization of the composites under this investigation reveals that the trends observed in regard to the compressive strengths are quite different from those obtained in the case of tensile strength variations with the filler loading. It is also observed that these LD sludge filled composites show improved micro-hardness and low amount of porosity.

Preparation and characterization of Ba4Co2Fe36O60 filled PP composites

Phase pure U type hexaferrites having molecular formula Ba4Co2Fe36O60 is synthesized through solid state route as filler for the fabrication of magneto-dielectric (MD) composite. Being a MD material the U type hexaferrite has a promising future in information and communication sector as a base substrate for electronic circuits. Since they exhibit both electric and magnetic properties, they can contribute effectively to circuit miniaturization and bandwidth enhancement compared to an antenna printed on a dielectric substrate. The filler material is then blended with PP (Poly Propylene) matrix and Magneto dielectric substrates are produced via hot pressing technique. Filler concentration has been varied from 70 to 90 wt. % in PP matrix and ascertained amount of optimum filler fraction for dimensionally stable substrate having acceptable properties. Dielectric and magnetic characterizations have been done using Impedance analyzer. It is found that the density of the composite and the dielectric constant is increasing with the increase in filler loading up to an optimum level and further filler loading reduces the density as well as the dielectric constant due to increased porosity. For optimum filler loading a maximum density of 2.96 g/cm3 is achieved. Relative permeability values are found increasing with filler loading even beyond the optimum filler loading. The optimum loaded poly Propylene/Ba4Co2Fe36O60 composite has an effective dielectric constant of 9.21, loss tangent of 0.083, relative permeability of 3.6 and a magnetic loss of 0.060 at 1MHz. Coefficient of thermal expansion (CTE) of the composite has been investigated using thermo mechanical analyzer. Moisture absorption rate of the optimum filler loaded composite is studied and found to be less than 0.1%. Relatively good dielectric constant, low loss tangent together with better relative permeability make the Ba4Co2Fe36O60 filled PP composites an excellent choice as Microwave substrate.

Biocomposites based on date palm flour reinforced (70/30) polypropylene/thermoplastic starch blend: Effects of flour treatment and selective dispersion

In this work, biocomposites have been prepared from a matrix consisting of polypropylene (PP) and thermoplastic starch (TPS) compatibilized using maleic anhydride (MA) grafted PP (PP-g-MA) and flour obtained from local date palm trees (DPF). To mediate the high hydrophilic character of the filler and attain an optimal dispersion, MA treated DPF (MA-DPF) was prepared via DPF esterification. Pretreated and MA treated DPF composites have been prepared by incorporating 10, 20 and 30% of the flour. MA-DPF has also been dispersed according to a second method consisting of dispersing the flour into starch/glycerol mixture before plasticizing to obtain MA-DPF modified TPS batches that were incorporated into PP to get the same matrix composition and flour loadings as for the first composites. The study of the composites properties proved the MA-DPF efficiency in increasing their impact resilience and diminishing their aptitude to water absorption. This was possible due to the association of the MA-DPF/TPS existing interactions to the better affinity of the esterified flour for the PP phase through its reduced hydrophilic nature. Also, SEM analysis confirmed that the interesting impact and water resistances of MA-DPF modified TPS filled PP composites derive from the DPF reinforced TPS phase consisting the materials.

Investigation of thermal and mechanical properties of synthetic graphite and recycled carbon fiber filled polypropylene composites

Suppressing the through-plane component of the thermal conductivity caused by synthetic graphite (SG) alignment was decreased by loading of recycled carbon fiber (CF) into SG loaded polypropylene (PP) composites. The effect of CF loading into SG loaded PP composites on thermal stability, viscoelastic, and morphological properties were also investigated by thermogravimetric analysis, dynamic mechanical analysis, and scanning electron microscopy, respectively. CF loading into SG loaded PP composites increased through-plane conductivity considerably rather than in-plane conductivity. 20 wt% CF additions into 50 wt% SG increased through-plane and in-plane thermal conductivity values by 12.5 and 1.3 times, respectively. Storage and loss moduli of composites significantly increased with the increasing fiber weight content, particularly 20 wt%. Besides, while SG decreases the mechanical properties of PP, CF loading into SG loaded PP composites increased the mechanical properties.

Electrical Properties and Electromagnetic Interference Shielding Effectiveness of Interlayered Systems Composed by Carbon Nanotube Filled Carbon Nanofiber Mats and Polymer Composites.

The demand for multifunctional requirements in aerospace, military, automobile, sports, and energy applications has encouraged the investigation of new composite materials. This study focuses on the development of multiwall carbon nanotube (MWCNT) filled polypropylene composites and carbon nanofiber composite mats. The developed systems were then used to prepare interlayered composites that exhibited improved electrical conductivity and electromagnetic interference (EMI) shielding efficiency. MWCNT-carbon nanofiber composite mats were developed by centrifugally spinning mixtures of MWCNT suspended in aqueous poly(vinyl alcohol) solutions. The developed nanofibers were then dehydrated under sulfuric acid vapors and then heat treated. Interlayered samples were fabricated using a nanoreinforced polypropylene composite as a matrix and then filled with carbon fiber composite mats. The in-plane and through-plane electrical conductivity of an eight-layered flexible carbon composite (0.65 mm thick) were shown to be 6.1 and 3.0 × 10−2 S·cm−1, respectively. The EMI shielding effectiveness at 900 MHz increased from 17 dB for the one-layered composite to 52 dB for the eight-layered composite. It was found that the reflection of the electromagnetic waves was the dominating mechanism for EMI shielding in the developed materials. This study opens up new opportunities for the fabrication of novel lightweight materials that are to be used in communication systems.

A study on erosion wear behavior of ld sludge reinforced polypropylene composite

Abstract In this study, experiments are carried out for a set of Linz-Donawith (LD) sludge filled polypropylene composites by fabricating them through compression molding technique to find out their mechanical and erosion wear behaviour under controlled laboratory conditions. Taguchi’s experimental design is used to conduct the erosion wear trials on the fabricated polypropylene-LD sludge composite samples as per ASTM standard. Confirmation experiment is carried out to validate the conclusions drawn during Taguchi’s analysis. Results obtained from this analysis reveal that the impact velocity and the filler content are the most predominant factors influencing the erosion rate of the composite. Mechanical characterization of the composites under this investigation reveals that the trends observed in regard to the compressive strengths are quite different from those obtained in the case of tensile strength variations with the filler loading. It is also observed that these LD sludge filled composites show improved micro-hardness.