PP Composites Research Articles

Synthesis of montmorillonite/modified graphene oxide filler and its effect on the properties of PP composites

This work reports the easy production of hybrid organoclays composed of Cloisite 20A and modified graphene oxide (r-mGO) at different proportions, and their effect on PP composites properties. In this way, it is proposed to evaluate both, the effect of the amount of r-mGO in the hybrid organoclay, and the effect of the amount of the hybrid organoclay on the PP composites. Morphological and structural details of PP composites were followed by scanning electron microscopy and X-ray diffraction, respectively. The thermal stability of the composites was analyzed by thermogravimetric analysis and differential scanning calorimetry, tensile mechanical properties were also tested. The results show that the obtained laminated hybrid material exhibited homogeneous intercalation of Cloisite 20A and r-mGO. The interactions among the clay intercalant molecules and graphene oxide grafting makes them remain united even in a polymeric matrix, acting as a good reinforcer and resulting in a rigid polymeric composite with improved mechanical properties at low content of the filler, mainly when having small amounts of r-mGO.

Damage mechanics of polypropylene‐based composites using progressive‐ and constant‐load scratching

AbstractPolypropylene (PP)‐based composites with reinforcements of CaCO3and rice husk ash (RHA, agricultural waste) are extensively used in textile industry and manufacturing of plastic yarns, tapes, etc. Tribological properties of the PP‐CaCO3‐RHA based composite are studied using constant‐ and progressive‐load scratching. The progressive load scratching depicts a transient‐state interaction, whereas, constant load scratching depicts steady‐state of wear, hence, both modes of scratching are reported to highlight the aspects of damage initiation and damage tolerance on PP‐based composites. The average scratch hardness and toughness of the PP composites improved with reinforcement in both modes of scratching. The reinforcement of 20 wt% RHA and 10 wt% RHA with 10 wt% CaCO3 in PP matrix, marginally improves (0.8%‐1.6%) the wear resistance (wear rate, WR of 12.1‐12.2 mm3 N−1 m−1) during the progressive load scratching compared to that of pure PP (12.3 mm3 N−1 m−1). Poor wear resistance (WR = 12.6 mm3 N−1 m−1) with the addition of 20 wt% CaCO3 in PP matrix during the progressive wear is attributed to poor adhesion (adhesion factor: 0.61) of CaCO3 with PP. Also, an over estimation (3.4‐4.6 times) of wear rate is attributed to high recovery (0.63‐0.77) and the plastic deformation ahead of the scratch tip in the PP‐based composite with viscoelastic nature. High‐wear rate with CaCO3 agglomerate with poor sinterability at 200 °C can be substituted with the strong adhesive nature of RHA (bimodal pore distribution) in PP matrix to achieve optimal hardness, elastic modulus, and scratch resistance.

Valorization of Hemp Core Residues: Impact of NaOH Treatment on the Flexural Strength of PP Composites and Intrinsic Flexural Strength of Hemp Core Fibers.

Hemp core is a lignocellulosic residue in the production chain of hemp strands. Huge amounts of hemp core are gathered annually in Europe (43,000 tons) with no major application end. Such lignocellulosic wastes have potential as filling or reinforcing material to replace synthetic fibers and wood fibers in polymer composites. In this study, hemp core biomass was treated under different NaOH concentrations and then defibrated by means of Sprout Waldron equipment to obtain single fibers. Polypropylene matrix was reinforced up to 50 wt.% and the resulting hemp core fibers and the flexural properties were investigated. The results show that the flexural strength of composites increased with the intensity of NaOH treatment. The effect of NaOH was attributed to the removal of extractives and lignin in the fiber cell wall leading to improved interfacial adhesion characteristics. Besides, a methodology was established for the estimation of the intrinsic flexural strength of hemp core fibers. The intrinsic flexural strength of hemp core fibers was calculated to be 940 MPa for fibers treated at 10 wt.% of NaOH. In addition, a relationship between the lignin content and the intrinsic strength of the fibers was established.

Effect of a novel treatment fiber on mechanical properties, thermal stability and crystallization behaviors of epoxy soybean oil toughened jute fiber/polypropylene composites

AbstractIn this work, a novel fiber treatment method is introduced in the preparation of epoxy soybean oil (ESO) toughened jute fiber/polypropylene (PP) matrix composites. The jute fibers are pre‐treated by r‐valerolactone (GVL), and the ESO/jute fiber/PP composites are fabricated by melt blending. The microstructure of the treated fiber, the mechanical properties, thermal stability, and crystallization behaviors of the composites are investigated and discussed in detail. The results show that the surface of GVL treated fiber becomes rough and the aspect ratio increases. It is found by scanning electron microscopy (SEM) that the interface between the fiber and matrix debones seriously without the addition of ESO. With increasing the content of ESO, the toughness and thermal stability of the composites are gradually improved. The tensile strength of the composites containing 5% ESO reaches 42.2 MPa. In addition, the impact strength and elongation at break are higher than pure PP and PP/jute composites. Moreover, GVL treated fibers can improve the thermal stability of PP/jute fiber composites. In addition, the crystallinity of PP in the PP composites increases first and then decreases, while the crystallization temperature of the composites decreases. At the same time, the complex viscosity of the composites also increases.

바이오매스 기반 종이 플라스틱의 제조 및 응용에 대한 고찰

Recently, applications of biomass-based plastics have increased according to the eco-friendly policy of the reduction of carbon dioxide emissions in domestic and foreign government. In this study, a paper plastic composite was produced by compounding polypropylene and micronized paper powder that was prepared using dry pulverization technology. Subsequently, the specimen of paper plastic was verified with mechanical properties, formability and product safety test to confirm the suitable packaging materials for food packaging. Paper plastics showed slightly lower mechanical properties than currently commercialized PP composites. However, paper plastics are valuable materials as environmentally friendly carbon-reducing material because of high biocarbon content, light weight features and applicability of existing manufacturing machines or system.

Synergistic fire retardant effect between expandable graphite and ferrocene-based non-phosphorus polymer on polypropylene

The key point to enhance the flame retardancy of expandable graphite (EG) in polymeric materials is to weaken the excessive intumescence of EG during combustion. Herein, a kind of ferrocene-based polymer (PDPFDE) is introduced into the flame retardant polypropylene (PP/EG) system. The fire retardant performance of PP composites was investigated by limiting oxygen index (LOI), vertical burning (UL-94) and cone calorimeter (CC) tests. With 20 wt% EG and 5 wt% PDPFDE added, the sample (PP3) passed the UL-94 V-0 rating, and its LOI value increased from 17% to 28.8% compared with neat PP (PP0). In contrast to PP0, CC data showed that the PP3 had a significantly depressed the peak heat release rate (pHRR) by 82.7%, and the total heat release (THR) by 41.0%. The thermal stability of PP composites and the synergistic effect between EG and PDPFDE were also studied by TGA and XRD. SEM and Raman analysis of the char residues of PP composites after UL-94 tests indicate that PP3 can produce dense char residue with a high degree of graphitization.

Low velocity impact response of flax/polypropylene hybrid roving based woven fabric composites: Where does it stand with respect to GRPC?

Flax-PP based thermally bonded roving (TBR) has a unique structure where the flax fibres remain twist-free and fully aligned along the roving axis. The present study describes an experimental investigation on the low velocity impact (LVI) behaviour of the TBR based woven fabric composites and compares the same with plain woven glass fabric reinforced PP composites (GRPC). Two different fabric architectures namely plain woven (PW) and unidirectional (UD) are fabricated using flax/PP based TBR. These TBR based woven fabrics and the glass fabric/PP sheets are consolidated in a compression moulding machine and the resultant composite-laminates are tested for their LVI behaviour. The impact test results revealed that the glass/PP composites absorb more energy and exhibit a higher peak load than both TBR based PW and UD fabric composites. However, the specific load and energy of all flax/PP composites are higher than the glass/PP composite. The damage tolerance of all composite laminates are evaluated by comparing their flexural strength before and after the impact. It is observed that the proportionate loss in flexural strength due to impact thrust is larger in case of glass/PP composites than all flax-PP composites.

Flame retardant synergy between interfacial and bulk carbonation in glass fiber reinforced polypropylene

Abstract Glass fiber reinforced polypropylene (GF-PP) composites have high flammability on account of wick effect which leads to accelerated flow of the polymer melt along the glass fibers (GF) surface to the flame zone. In this study, dipentaerythritol (DPER), a charring agent, was adsorbed on the GF surface through the hydrogen bond between silane coupling agent and DPER. DPER has a synergistic effect with the intumescent flame retardants (IFR) added in the composites, which can induce interfacial carbonization on the surface of GF, thus transforming the intrinsic smooth GF surface into roughness one. In this way, the negative effect of the wick effect in flame retardancy is weakened. Moreover, the char residues remained on the surface of GF can bring an improved adhesion between GF and char residues formed in the resin so that a more stable barrier char layer is formed. The PP composites with 20 wt% modified glass fiber (M-GF) and 30 wt% IFR can achieve the UL-94V-0, and its limiting oxygen index (LOI) value increased from 16.5% to 29.5%. Simultaneously, the heat release rate (HRR), total heat release (THR) and total smoke release (TSR) decreased significantly, and the peak of heat release rate (PHRR) reduced 60.6% compared with GF-PP.

Joint‐aggregation intumescent flame‐retardant effect of ammonium polyphosphate and charring agent in polypropylene

AbstractIn order to explore the structure mode of intumescent flame retardants (IFRs) with higher efficiency, IFR particles with joint‐aggregation structure (@IFR) were obtained through the treatment of ammonium polyphosphate (APP) and a charring agent (PT‐Cluster) in their aqueous solution. Then, the joint‐aggregation IFR effect was researched using its application in polypropylene. In case of 20 wt% IFR loading, the limiting oxygen index (LOI) value of @IFR/PP was 1.1% higher than that of 15APP/5PT‐Cluster/PP mixture, and a 1.6 mm‐thick @IFR/PP composite passed the UL 94 V‐2 rating test, while 15APP/5PT‐Cluster/PP demonstrated no flame‐retardant rating in UL 94 vertical burning tests. In a cone calorimeter test, @IFR also had a better inhibition effect on heat release. The average heat release rate (av‐HRR) value during 0 to 120 seconds of @IFR/PP was only 41 kW m−2, which was 33.9% lower than that of the 15APP/5PT‐Cluster/PP. Furthermore, the peak heat release rate (pk‐HRR) of @IFR/PP was 20.5% lower than that of 15APP/5PT‐Cluster/PP, and the time to pk‐HRR of @IFR/PP was 710 seconds, while that of 15APP/5PT‐Cluster/PP was 580 seconds. The better inhibition effect on HRR and the delay of time to pk‐HRR were caused by the joint‐aggregated structure of @IFR, which can rapidly react to form stable and efficient char layers. This kind of join‐aggregation IFR effect has great significance in suppressing the spread of fire in reality. In addition, @IFR also increased the mechanical properties of PP composites slightly compared with the APP/PT‐Cluster mixture.

Mechanical, physical and biodegradability performances of treated and untreated groundnut shell powder recycled polypropylene composites

In this study, groundnut shell powder (GSP) was used for the reinforcement of recycled polypropylene (recycled PP). The GSP consisting of two-particle sizes viz (0–250 μm and 250–420 μm) was partly treated with sodium hydroxide at room temperature and the GSP both treated and untreated were compressed and compounded with recycled PP to produce GSP-recycled PP composites. For comparison, recycled PP was equally produced as a control sample. The effects of GSP addition and sodium hydroxide treatment on recycled PP were investigated through the mechanical testing of the developed composites. The mechanical properties (tensile strength, hardness, and toughness) of the composites were evaluated and the tensile strength of both treated and untreated GSP-recycled PP composites is higher than the recycled PP and the treated GSP of particle size 0–250 μm having the highest tensile strength at 25 wt% GSP in recycled PP matrix. The hardness of the recycled PP increases with increasing content of GSP while the toughness decreases with increasing concentration of GSP in the recycled PP matrix. The water uptake of the GSP-recycled PP composites was equally studied, and the results revealed that the treated GSP-recycled PP composites has lower rate of water absorption as compared to untreated GSP-recycled PP composites Thermal stability and crystallinity of the composites and monolithic recycled PP were investigated, and it was discovered that the thermal stability and crystallinity of the polymer were enhanced with GSP addition. Morphological characterization of the selected samples through a scanning electron microscope (SEM) and x-ray diffraction (XRD) were equally done to validate the mechanical performance of the composites. Finally, biodegradability study on the composites and the control sample was conducted and it was found out that, the addition of GSP in both forms promotes the biodegradation of the recycled PP polymer. Such biodegradable GSP-recycled PP polymer composite materials are highly valuable for manufacturing food takeaway packages and some of the interior parts of the automobiles.

A comparative life-cycle assessment of talc- and biochar-reinforced composites for lightweight automotive parts

The use of renewable materials and cleaner production is currently the target of the automotive industry to reduce the use-phase environmental impacts of vehicles. Renewable lightweight materials are used to replace conventional materials to produce lightweight automotive parts, leading to reduced fuel consumption, which contributes toward meeting the industry’s environmental impact target. In this study, we compared the life cycle of a conventional composite to that of a biocomposite for automotive applications using the standard set by the International Standards Organization (ISO 2006). The conventional one is talc-reinforced polypropylene composite (talc–PP) at a 70% PP to 30% talc weight ratio. The biocomposite is Miscanthus biochar-reinforced polypropylene composite (MB–PP) at a 70% PP to 30% MB. The functional unit is 982 cm3 of composite used for a certain vehicle part (i.e., an automotive component). The environmental impacts are determined using the Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI, v2.1). The system boundary includes material extraction to the disposal stage of the composites. The results revealed that MB–PP composite had the least impact for all categories than talc–PP composite and appeared to be a favorable option for automotive parts from an environmental perspective. This study indicates that MB-PP can reduce about 25% environmental impacts of the life of composite if it replaces the talc–PP composite. The MB–PP composite emerged as a promising option than talc–PP composite and has environmentally benign green credentials for automotive parts application.

The Influence of Natural Fiber Reinforcement on the Mechanical Properties of Polyolefin-Based Hybrid Composites

In this study, effects of natural fiber reinforcement on mechanical properties of polyolefin based hybrid composites widely used different industrial areas were investigated. In this context, jute - PP composites having different jute ratios are produced in twin screw extruder on first stage of production. In the second stage, the films are produced at 450 µm thickness of PP material with different jute ratios are placed between HDPE (S 0464) plates with a thickness of 1 mm and are pressed under a pressure of 8.163 bar and temperature of 190 °C and consequently hybrid polyolefin composite sheets are obtained. The improvement of mechanical strength of hybrid composite material is realized 8.6 % ratio as 18.41 MPa in 5% jute reinforced hybrid composite. As a result of FTIR characterization, it is observed that the interface agents affecting the mechanical strength positively are significant. When SEM analysis of fracture surfaces formed after tensile test is performed, it is determined that an effective interface is formed between the fiber and the polymer, wheras the fibers that change direction due to production methods adversely affected the mechanical strength.

Characteristic Investigation and Comparison between Vetiver fiber -reinforced polypropylene and polyethylene with Coconut shell powder and Maleic anhydride as filler and coupling agents

The last two decennium have witnessed enormous development in natural fiber reinforcement polymer composites in direction towards bio-degradable products. Natural fibers as compared to synthetic fibers are having higher strength, rigidity and also in supporting the structural load of matrix. Vetiver fiber is used as reinforcement for the polymer composites with polypropylene and polyethylene as matrix material. In view of enhancing the degree of bio-degradability coconut shell powder is used as filler. Fibers are chemically treated with saline solution for better adhesive property and maintain required properties of composite. Further maleic anhydride is added to increase interface adhesion between the fibers and matrix. The characteristics investigation is carried by preparing specimens having weight percentage of each fiber and filler being varied from 10% to 25% and remaining of individual polymers. The injection molding technique was engaged to produce composite specimens for various mechanical tests. The mechanical properties, viz. tensile strength, modulus, flexural strength and hardness for PP composites and PE composites are done separately and compared. In conjunction, TGA analysis was carried to ascertain the thermal stability of PP composites and PE composites

Influence of composite architecture and interfacial bonding on their impact properties

Resistance to impact thrust is one of the most important requirement along with many others for defining suitable applications of any composite materials. In this present work, the influence of composite architecture and composite interfacial bonding strength on the impact performance of flax reinforced PP composites have been investigated. In this regard two different composite architecture through conventional film stacking method and through DREF (DR. E. Fehrer open-end friction spinning process) yarn consolidation method have been produced and to alter the fibre–matrix interfacial bonding the flax fibres are treated with MAgPP (Maleic Anhydride grafted Polypropylene). Finally, the notch Izod impact behaviour of all composite samples are evaluated and compared.

A quick response and tribologically durable graphene heater for rapid heat cycle molding and its applications in injection molding

A novel one-step approach was employed to achieve direct, high-strength graphene coating on a silicon wafer through chemical vapor deposition (CVD). The coated graphene on the silicon wafer was then assembled into a thin-film heater to realize rapid heat cycle molding (RHCM) with significantly enhanced thermal management and response. As soon as the applied power was turned on, the temperature rose immediately. The surface temperature of the graphene heater increased with the applied power and time, and the highest temperature exceeded 300 °C. The average heating rate reached 11.6 °C/s at an applied power of 360 W. Four-point temperature testing and temperature response during cyclic heating and cooling showed great temperature uniformity and stability. A tribology test was carried out to characterize the wear resistance of the graphene coating as a function of different coating times. As the coating time (graphene thickness) increased, the coefficient of friction (COF) for the coating decreased, and the wear resistance increased. The graphene heater with a 48 Ω surface resistance made by a 60 min coating time proved to be the best choice for RHCM with regard to the heating efficiency. The graphene heater was used in the RHCM of long-glass-fiber-reinforced (LGFR) PP composites to reduce the width and depth of the weld lines, decrease the floating fiber phenomenon, and improve the surface quality. The graphene heater also has great potential in other high-precision molding applications that require smooth surface, low molded-in residual stresses and birefringence, and superior replication of surface microstructures.

Cellulose modified by citric acid reinforced polypropylene resin as fillers

The greatest challenge hindering the use of cellulose as a reinforcing filler in polymeric composites is its poor compatibility due to the inherent hydrophilicity of cellulose and the hydrophobic nature of polymeric matrices. To solve this issue, we demonstrate an effective water-based method to render the cellulose surface with high carboxyl content through the esterification of hydroxyl groups with citric acid in a solid phase reaction without the use of noxious solvents. The modified cellulose was then further hydrophobized by grafting magnesium stearate to the surface. Consequently, the flexural properties of PP composites reinforced by the hydrophobized cellulose fillers were greatly improved compared to those of composites containing hydrophilic cellulose and pure PP resin. The surface modification conditions and filler proportions in composites were optimized. Because of the innocuity and cost-efficiency of citric acid, we believe that citric acid-modified cellulose has immense potential as a sustainable and cost-effective reinforcing filler.

The influence of adding marble and granite dust on the mechanical and physical properties of PP composites

The purpose of this work is to investigate the opportunity of re-using M&G wastes to get novel PP composites. Recycling of marble and granite (M&G) wastes has the advantage of cost reduction and eco-friendly production. M&G productions generate a large amount of wastes. The handling of such wastes by incorporating them into a polymer is a practical solution for waste management. These composites can be utilized in several applications to produce low-cost products. The effect of the mass percentage of marble and granite dust on several mechanical and physical properties was examined. The mechanical (pin load behavior) and physical (thermal, water absorption and density) properties of PP composites were investigated using 0–50 mass% M&G dust particles. Adding M&G wastes increases the onset temperature.

Spray‐free polypropylene composite reinforced by graphene oxide@short glass fiber

AbstractPolypropylene (PP) is widely used in the automotive industry due to its excellent mechanical properties, good formability, and low cost. Herein, the spray‐free PP composites reinforced by graphene oxide@short glass fiber (GO@SGF) were fabricated by extrusion compounding and injection molding. Aluminum powder was used as spray‐free filling materials. The microstructure and composition of SGF and GO@SGF are investigated using scanning electron microscopy and X‐ray photoelectron spectrometer. The effect of GO@SGF on the mechanical properties of spray‐free PP composites was studied. The results showed that both tensile strength and modulus were effectively improved by incorporation of GO@SGF. This mainly attributed to the improved interfacial bonding between the reinforcements and matrix.

PP および PVA 繊維補強セメント複合材料の動的一軸圧縮特性に関する実験的研究

PP および PVA 繊維補強セメント複合材料の動的一軸圧縮特性に関する実験的研究

High flow polypropylene/SEBS composites reinforced with differently treated hemp fibers for injection molded parts

Polypropylene/hemp fibers (PP/HF) composites for injection molded car parts show several advantages compared to similar composites containing glass fibers (GF), however they have low impact strength, tensile strength and modulus. Here, hemp fibers modified by alkali and alkali-silane treatment were used to reinforce a polypropylene matrix modified with maleic anhydride grafted polypropylene (MAPP) and SEBS. The addition of HF in PP modified with MAPP and SEBS has increased not only the tensile strength and modulus (by 45% and 230%) but also the impact strength. Double tensile strength and triple Young's modulus were obtained in PP composites with alkali-silane treated HF (HFs) in the presence of MAPP and SEBS. Similarly, the HFs led to a significant increase of storage modulus, with about 100% at room temperature and with about 200% at 120 °C. Moreover, the onset degradation temperature increased with 51 °C for HFs containing composites compared to neat PP. PP/HFs composites modified with MAPP and SEBS showed improved mechanical and thermal properties, being considered as a viable alternative to PP/GF composites for injection molded parts in the automotive industry.