Coupling Agent Maleic Anhydride Research Articles

Fabrication of ecofriendly composites using low-density polyethylene and sugarcane bagasse: Characteristics’ degradation

In recent years, research into replacing synthetic fibers with natural fibers as reinforcements in thermoplastic composites has developed rapidly. The main objective of this work is to produce eco-friendly and cost-effective composite material. This material consists of natural fiber of sugarcane bagasse as the reinforcing component and thermoplastic polymer of low-density polyethylene as a matrix. The injection molding technique was used to produce the test samples. The fabricated composite contained 30 wt.% sugarcane bagasse. The effects of natural fiber sugarcane bagasse content, chemical treatment, and the addition of maleic anhydride as coupling agent on the composite degradation were studied. The degradation of sugarcane bagasse/low-density polyethylene composite under ultraviolet radiation and the thermal degradation were investigated. In addition, the amount of absorbance ultraviolet radiation by the fabricated composites was studied using ultraviolet-visible spectroscopy in the range from 200–800 nm. The effect of carbon black particles added to the fabricated composite on the degradation by ultraviolet exposure was also investigated. The results showed that the compatibilized sugarcane bagasse/low-density polyethylene composites at 3 wt.% maleic anhydride concentration revealed a higher decomposition temperature (466°C) than that of the uncompatibilized composites (460°C). This ensures that the thermal degradation temperature was improved by using the maleic anhydride coupling agent. Moreover, using the coupling agent showed significant resistance to degradation by ultraviolet exposure. Furthermore, the addition of 2.5 wt.% carbon black enabled more resistance to degradation by ultraviolet exposure.

Effect of temperature on the fiber-matrix adhesion in glass fiber reinforced thermoplastics

The apparent interfacial shear strength (IFSS) between sized glass fiber and neat high-density polyethylene (HDPE), HDPE with a maleic anhydride coupling agent, polyamide 6 (PA6), and polybutylene terephthalate (PBT) has been measured from 20 °C to 80 °C. A modification of a custom set-up involving the single fiber pullout test has been used to perform the characterizations. The calculation of radial stresses on the fiber due to polymer shrinkage during sample cooling has been conducted using data from dynamic mechanical analysis and thermomechanical analysis. A strong inverse relationship was found between IFSS and temperature. The IFSS of neat HDPE, PA6, and PBT decreased by 44% from 20 °C to 80 °C. Over the same temperature range the IFSS of HDPE with the coupling agent decreased by 66% but remained greater than neat HDPE. The effects of glass transition (Tg), measured to be 50 °C for PA6 and 68 °C for PBT, on IFSS were noticeable through analysis of the single fiber pullout data.

Molecular Dynamics Simulations on the Elastic Properties of Polypropylene Bionanocomposite Reinforced with Cellulose Nanofibrils.

Cellulose-reinforced polypropylene bionanocomposites can show improved elastic properties over their pure polypropylene counterparts. We have used equilibrium and non-equilibrium molecular dynamics (MD) simulations to study the elastic properties of polypropylene bionanocomposite systems composed of cellulose nanofibrils (CNF), polypropylene (PP) matrix, and maleic anhydride (MAH) coupling agent. The components of the bionanocomposite were parametrized for compatibility with the AMBER14SB force fields. The elastic properties of pure PP systems converge for the chains with at least 20 monomers. The ratio of cellulose in CNF-PP bionanocomposites strongly affects their elastic properties. The elastic modulus of CNF-PP bionanocomposites shows small improvement when the adhesion between hydrophobic and hydrophilic components is facilitated by a MAH coupling agent. The results demonstrate how fully-atomistic MD simulations can be systematically used to evaluate the elastic properties of CNF-PP bionanocomposites and to make predictions that are in agreement with experiments.

Interfacial adhesion and thermal stability of high-density polyethylene glass fiber composites

The fiber-matrix adhesion and the thermal stability of glass fiber reinforced high-density polyethylene composites with increasing content of maleic anhydride coupling agent and zinc-based thermal stabilizer have been analyzed by the single fiber pullout test and oxidation induction time. High-density polyethylene compounds containing 8% by weight maleic anhydride grafted polyethylene increases the apparent interfacial shear strength to glass fibers by 3.5x; however, the strength was reduced by 45% with the addition of the thermal stabilizer. The thermal stabilizer was found to greatly improve the oxidative resistance. The oxidation induction time of the non-stabilized compounds is less than 1 min compared to over 25 min for the stabilized high-density polyethylene blends.

Experimental and numerical analysis of the ballistic response of agglomerated cork and its bio-based sandwich structures

Considering the susceptibility of sandwich structures to impact events and the increasing environmental awareness due to pollution, the present work provides a thorough understanding of the ballistic impact behavior of agglomerated cork and of the resulting green sandwich structures produced with polypropylene (PP) skins reinforced with a flax/basalt intraply hybrid fabric. The effect of density on the agglomerated cork response was evaluated (NL10 ρ = 0.14 g/cm3, NL20 ρ = 0.20 g/cm3 and NL25 ρ = 0.25 g/cm3) and a comparison with commercial polyvinyl(chloride) foams was provided (HP130 ρ = 0.13 g/cm3, HP200 ρ = 0.20 g/cm3 and HP250 ρ = 0.25 g/cm3). The effect of a maleic anhydride coupling agent on the mechanical properties of the skins and of the overall sandwich structures was also investigated. The results highlighted a compromising effect of the weak interface between cork granules and polymeric binder on the impact resistance of the agglomerated cork, but a clear improvement of its performance was observed when embedded as core material between the two skins. Indeed, the two classes of sandwich structures produced with neat PP skins and with the two cores with the same density, i.e. agglomerated cork NL10 and PVC foam HP130, displayed the same ballistic limit of 171 m/s confirming that cork integration in the overall structures allows to approach PVC foam performance. The high-velocity impact response of one agglomerated cork (NL25) and one PVC foam (HP130) was also subjected to finite element analysis employing the CRUSHABLE FOAM model available in ABAQUS obtaining a good fitting with the experimental data.

Properties of Wood-Plastic Composites Manufactured from Two Different Wood Feedstocks: Wood Flour and Wood Pellets.

Driven by the motive of minimizing the transportation costs of raw materials to manufacture wood–plastic composites (WPCs), Part I and the current Part II of this paper series explore the utilization of an alternative wood feedstock, i.e., pellets. Part I of this study reported on the characteristics of wood flour and wood pellets manufactured from secondary processing mill residues. Part II reports on the physical and mechanical properties of polypropylene (PP)-based WPCs made using the two different wood feedstocks, i.e., wood flour and wood pellets. WPCs were made from 40-mesh wood flour and wood pellets from four different wood species (white cedar, white pine, spruce-fir and red maple) in the presence and absence of the coupling agent maleic anhydride polypropylene (MAPP). With MAPP, the weight percentage of wood filler was 20%, PP 78%, MAPP 2% and without MAPP, formulation by weight percentage of wood filler was 20% and PP 80%. Fluorescent images showed wood particles’ distribution in the PP polymer matrix was similar for both wood flour and ground wood pellets. Dispersion of particles was higher with ground wood pellets in the PP matrix. On average, the density of composite products from wood pellets was higher, tensile strength, tensile modulus and impact strength were lower than the composites made from wood flour. Flexural properties of the control composites made with pellets were higher and with MAPP were lower than the composites made from wood flour. However, the overall mechanical property differences were low (0.5–10%) depending on the particular WPC formulations. Statistical analysis also showed there was no significant differences in the material property values of the composites made from wood flour and wood pellets. In some situations, WPC properties were better using wood pellets rather than using wood flour. We expect if the material properties of WPCs from wood flour versus wood pellets are similar and with a greater reduction in transportation costs for wood pellet feedstocks, this would be beneficial to WPC manufacturers and consumers.

Effect of temperature on the low-velocity impact response of environmentally friendly cork sandwich structures

Impact events are common in every-day life and can severely compromise the integrity and reliability of high-performing structures such as sandwich composites that are widespread in different industrial fields. Considering their susceptibility to impact damage and the environmental issues connected with their exploitation of synthetic materials, the present work aims to propose a bio-based sandwich structure with an agglomerated cork core and a flax/basalt intraply fabric as skin reinforcement and to address its main weakness, i.e. its impact response. In-service properties are influenced by temperature, therefore the effect of high (60 °C) and low (−40°C) temperatures on the impact behavior of the proposed structures was investigated and a suitable comparison with traditional (polyvinyl chloride) (PVC) foams was provided. The results highlighted the embrittlement effect of decreasing temperature on the impact resistance of the sole cores and skins and of the overall structures with a reduction in the perforation energy that shifted, in the last case, from 50–60 J at – 40 °C up to more than 180 J at 60 °C. A maleic anhydride coupling agent in the skins hindered fundamental energy dissipation mechanisms such as matrix plasticization, determining a reduction in the perforation threshold of all composites. In particular, neat polypropylene (PP) skins displayed a perforation energy of 20 J higher than compatibilized (PPC) ones at 60 °C, while agglomerated cork sandwich structures at 60 °C were characterized by a perforation threshold higher of at least 50 J.

Temperature effect on the single and repeated impact responses of intraply flax/basalt hybrid polypropylene composites

AbstractLow‐velocity impacts can severely jeopardize the structural reliability of polymer composites. In view of this, the present work provides a thorough overview of the impact response of polypropylene (PP) composites reinforced with an ecofriendly intraply flax/basalt hybrid fabric, assessing the effect of different parameters: energy level, temperature, and number of impacts. Indeed, high‐energy single impacts are as dangerous as low‐energy repeated impacts for the structural integrity of laminates. Moreover, considering the poor interfacial adhesion between hydrophobic polyolefin matrices and hydrophilic vegetable fibers, the effect of a maleic anhydride coupling agent was evaluated. A detrimental effect of coupling agent on composites impact response was observed, determining a reduction of the impact life (impacts to failure from 83 to 63 at 10 J and from 30 to 9 at 15 J) because several energy dissipation mechanisms were prevented. Decreasing temperatures (−40°C) caused an embrittlement effect on neat PP composites with an increase between 7.3% and 20.3% of maximum force and a decrease between 7.5% and 10.9% of maximum displacement, whereas increasing temperatures (80°C) led to a softening of compatibilized composites with a decrease between 13.8% and 27.5% of maximum force and an increase between 28.1% and 34.4% of maximum displacement.

Comparing mechanical properties of impact modified polypropylene-copolymer (IMPP) from injection molding (IM) and fused layer modeling (FLM) processes

Purpose The purpose of this study was to produce dimensionally accurate and reliable fused layer modeling (FLM) feedstock composed of an impact modified polypropylene matrix, compounded with a cellulose nanofiber (CNF) reinforcement and coupled by a maleic anhydride coupling agent to produce comparable mechanical properties in comparison to the industry-standard method of injection molding (IM). Design/methodology/approach A spray dried CNF (SDCNF) was compounded with the polymer matrix using a masterbatch method. The composite was diluted with neat polymer and extruded into a filament and then printed into standardized mechanical testing samples. For comparison, the filament was chopped and standardized samples were produced with IM. Findings A loss in mechanical properties of up to 30% was observed in FLM samples. If normalized to reflect improved density from a part consolidation method, losses are reduced to 15% or show improvements in the neat polymer matrix. Originality/value Limited research has been done on producing FLM feedstock, reporting mechanical property results based on standardized testing and comparing the same material with IM.

Degradation in the mechanical and thermo-mechanical properties of natural fiber filled polymer composites due to recycling

To manage the plastic waste, recycling is recognized as the most environment-friendly and non-destructive method. The aim of this research is to investigate the recyclability of oak wood flour (WF) filled high density polyethylene (HDPE) composites. Two different composite formulations (30 and 50 wt% filler) were considered, each with 3 wt% coupling agent maleic anhydride (MA). Both composites were individually reprocessed six times by extrusion. Test samples were injection molded, to measure mechanical and thermo-mechanical properties. Fiber length measurement and gel permeation chromatography (GPC) were performed respectively to examine the change on fiber length and molecular weight of polymer. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and Fourier Transform Infra-Red Spectroscopy (FTIR) were also carried out to better understand the impact of recycling on composite properties. After reprocessing six times, WF-HDPE composites showed relative decrease in strength and stiffness properties and slight increase in strain properties as compared to corresponding virgin composite. The strain properties saw an increase in their value with recycling. The crystallinity of HDPE decreased but thermal stability of the composite increased with reprocessing.

Glass Fiber/Waste Cotton Fabric Reinforced Hybrid Composites: Mechanical Investigations

In this study, the hybridization effect on the mechanical properties of the natural fiber reinforced composites was investigated. For this purpose, glass fibers in different ratios of 2.5, 5 and 10 wt% were added in the polymer composites with cotton fibers at the ratios of 12.5 and 25 wt%. In order to have better interfacial bonding and increase the effectiveness of glass fiber on the mechanical properties, maleic anhydride coupling agent was added in the hybrid composite structures. At the end of the study, the best ratios of maleic anhydride, cotton and glass fiber for this kind composites were explored with respect to the economical and mechanical concerns. This study suggests that hybridization can be considered as most promising way to improve the mechanical properties for this novel composite materials.

Long discontinuous carbon fibre/polypropylene composites for high volume structural applications

A processing route is presented to manufacture discontinuous carbon fibre-reinforced polypropylene composites, using much longer fibre lengths (25 mm) and higher volume fractions (up to 45%) than previously reported in the literature. Carbon fibre tows are coated with different ratios of polypropylene, blended with a maleic anhydride coupling agent, to investigate the influence of the interfacial shear strength at the microscale on the macroscale composite properties. Improvements in the tensile performance at the macroscale (70% increase) are not as high as those reported for the interfacial shear strength at the microscale (300%), following the addition of the coupling agent. Consequently, the tensile strength of the carbon fibre-reinforced polypropylene material is only 45% of values reported for carbon fibre/epoxy systems, however, the tensile stiffness is comparable. This demonstrates the potential for using carbon fibre-reinforced polypropylene for structural applications, following further process optimisation to overcome the current high levels of porosity (3.3% at 0.45 Vf) to improve the tensile strength.

Low-density polyethylene waste/recycled wood composites

The preparation of polymeric composites from recycled thermoplastic with natural fibers is an interesting alternative that contribute for preservation of natural resources, decrease of pollutant waste and production of low cost materials. Low-density polyethylene waste (LDPEW) from packaging films presents low index of mechanical recycling, generating several environmental problems and for their management after discard. On the other hand, wood waste as such as pine wood waste (PWW) are also produced in large scale and their recycling potential is not very explored. The aim of this study was the preparation of LDPEW/PWW composites in presence of coupling agent maleic anhydride grafted polyethylene (PE-g-MA) and to evaluate their mechanical, morphological and thermal properties. LDPEW/PWW composites were prepared by extrusion processing and specimens obtained by injection molding for after characterization by tensile testing, impact testing, scan electronic microscopy and thermal analysis. The mechanical properties of the LDPEW/PWW composites are depending of the PWW content in the material, allowing the adjustment of the composition according to the potential for practical application, while the thermal stability of the composites is compatible with the required conditions for thermomechanical processing. The preparation of LDPEW/PWW composites showed viability for production of low cost materials from recycled waste.

Effect of Fibre Content on Mechanical Properties and Water Absorption Behaviour of Pineapple/HDPE Composite

The present study investigates the effect of varying content of pineapple fibre in pineapple/HDPE composite on the tensile strength, tensile modulus, hardness (Shore-D)and water absorption behaviour. The content of pineapple fibres is kept as 5%, 15% and 25% (by wt.) and the HDPE matrix is taken as 50-50 mixture of fresh and recycled HDPE. The results obtained for 25% pineapple/HDPE composite are compared with those obtained for pineapple-sisal (each 12.5%)/HDPE composite. Prior to the fabrication of composite, the fibres were subjected to chemical treatments with NaOH and maleic anhydride coupling agent for enhancing their adhesion with HDPE matrix. It is observed that the tensile strength and hardness of pineapple/HDPE composite decrease with increasing fibre content. Though, the tensile modulus increases with the increase in fibre content. The pineapple-sisal/HDPE composite exhibits higher tensile strength and hardness, thought lower tensile modulus, as compared to pineapple/HDPE composite, when the total fibre content is 25% in both the composites.The 48 hours water absorption study indicates that amongst all the composites, the water absorption is the minimum for 5%pineapple/HDPE composite. SEM examination of the tensile fractured surface reveals that fibre pull-out, fibre delamination and fibre breakage are the primary mechanisms responsible for tensile failure of the specimen.

Experimental study on the glass fiber/waste cotton fabric-reinforced hybrid composites: Mechanical and rheological investigations

In this work, the effect of hybridization on the mechanical and rheological properties of the glass fiber/waste cotton fabric-reinforced hybrid composites was investigated. For this purpose, glass fibers in different ratios of 2.5, 5, and 10 wt.% were added to the polymer composites with cotton fibers at the ratios of 12.5 and 25 wt.%. In order to have better interfacial bonding and to increase the effectiveness of glass fiber on the mechanical properties, maleic anhydride coupling agent was added to the hybrid composite samples. At the end of the study, the best ratios of maleic anhydride, cotton, and glass fiber for this kind composites were explored with respect to the economical and mechanical concerns. This study suggests that hybridization can be considered as most promising way to improve the mechanical properties for this novel composite material.

Flax and its thermoplastic biocomposites

The potential of flax fabric in the production of ‘green’ composites based on polypropylene (PP) was evaluated. The laminate composites were prepared by compression molding of flax fabric (with and without treatment) and PP films (using different formulations of PP). The morphology and crystallization of the PP/flax composites were characterized using scanning electron microscope, X-ray diffraction, and differential scanning calorimetry. The mechanical performance of the composites was also evaluated. The results demonstrate that fiber treatment and PP formulation play important roles on the performance of composites. This study proved that the addition of the coupling agent maleic anhydride grafted PP to the composites improves the interfacial adhesion between hydrophilic flax fibers and the hydrophobic PP matrix and thus the mechanical properties. The combination of the coupling agent and reactive additive provides superior strength, modulus and brings further fire resistance to the PP/flax composites.

The usability of recycled carbon fibres in short fibre thermoplastics: interfacial properties

The objective of this study was to investigate the feasibility of combining discontinuous recycled carbon fibres with polypropylene, to produce a low-cost, high specific stiffness material for high-volume applications. The inherent low affinity of carbon fibre and polypropylene motivated a detailed study of the surface characteristics of carbon fibre and interfacial behaviour between the two materials, using the microbond test. The effects of removing the sizing from the fibres, as well as introducing a maleic anhydride-grafted polypropylene coupling agent, were extensively investigated. Polypropylene was found to degrade when prepared under atmospheric conditions; therefore, it was necessary to form droplets under nitrogen. Removal of the sizing from the fibre using pyrolysis and solvolysis techniques altered the surface morphology of the fibre and increased the interfacial shear strength (IFSS) by 4 and 33 %, respectively. A more significant improvement in the fibre–matrix adhesion was achieved by adding a maleic anhydride coupling agent at 2 wt%, which increased the IFSS by 320 %.

Effect of Nano-clay on Rheological and Extrusion Foaming Process of a Block-Copolymerized Polypropylene

The effects of nano-clay and the corresponding coupling agent maleic anhydride grafted polypropylene (PP-g-MAH) on thermal properties, rheological properties and extrusion foaming process of a block-copolymerized polypropylene (B-PP) were studied. Supercritical CO 2 (SC CO 2 ) was used as the foaming agent with a concentration of 5wt%. Each step of foamed B-PP/ PP-g-MAH/ nano-clay composites processing is addressed, including mixing of the composites, manufacture of the composites, foaming process of the composites and characterization of the cell structure. The results showed that incorporation of nano-clay and PP-g-MAH caused reduced melt strength and complex viscosity of B-PP. However, the heterogeneous nucleation induced by nano-clay and PP-g-MAH improved the maximum foaming expansion ratio and cell-population density of B-PP foam.

Mechanical Properties of High Loading <i>Luffa acutangula </i>Fiber with Cloisite 15A and Polypropylene

Matured luffa fibers can be used as reinforcing fillers for polymers to produce industrial products. Frequently, these fibers are incorporated in thermoplastics and thermosets binders at low loadings (1 – 40) wt % of total composition. In this project, high loadings of luffa fiber (50 to 70 wt %) were incorporated with polypropylene (PP), coupling agent maleic anhydride grafted polypropylene (MAPP) and Cloisite 15A using extrusion for compounding. (C15A) at 5 wt % was added for reinforcement and to increase density of compounded materials for ease of processing during mixing. The compounded material was pelletized and the test pieces were prepared using compression moulding and shaped according to the standard. The effects of fiber loadings on the mechanical properties of the composites were determined.

Towards improving mechanical properties of basalt fiber/polylactic acid composites by fiber surface treatments

Attempting to improve reinforcement effect on basalt fiber/polylactic acid composites, this study evaluates the effects of silane treatment, atmospheric glow discharge plasma polymerization, desizing, and addition of maleic anhydride coupling agent. The treated fibers were characterized, in terms of surface morphology and existing molecular bonds, and the mechanical properties of the composites were tested (i.e. strength, stiffness, and elongation at yield). Among the fiber surface treatments and the addition of coupling agent, improved mechanical properties were only shown by the silane treated and the atmospheric plasma polymerized composites by having 26 and 22% higher strength, respectively, as compared with the untreated one.