Investigation on physicomechanical and wear properties of new green thermoplastic composites

This study was aimed at fabrication of green composites of polypropylene (PP) matrix 5, 10, 15, and 20 wt% of saw palmetto spent (SPS) (a spent of nutraceuticals) as filler material. Two wt% organically modified montmorillonite clay (MMT) was used as a co‐filler in all formulations and composites were fabricated by melt blending. The fabricated PP/SPS/MMT composites were characterized for physicomechanical and tribological properties. Improvement in tensile modulus of the composites was noticed with increase in SPS content. The tensile strength of composites was decreased by 14% with increase in filler content from 5 to 20 wt%. Flexural strength of the composites increased from 31.3 to 37.8 MPa (21% improvement) and also flexural modulus improved from 956 to 1383 MPa (45% improvement) with increased SPS content. Composites were subjected to three‐body abrasion with different loads and abrading distances. Scanning electron microscope (SEM) study revealed that the predominant wear mechanisms of composite material sliding against continuous flowing sand were microploughing and filler detachment from the polymer matrix. POLYM. COMPOS., 37:2306–2312, 2016. © 2015 Society of Plastics Engineers     

Crystallization and melting of highly filled polypropylene composites prepared with surface‐treated fillers

Polypropylene (PP) composites with high filler content have been prepared with surface‐treated fillers. The effect of the filler is twofold; nucleation of crystallization occurs, though the PP is also adsorbed onto the filler thereby retarding its motion. Differential scanning calorimetry has been used to study the crystallization of the PP. Melting and recrystallization during melting has been characterized by differential scanning calorimetry. The properties of the composites are more than an additive combination of the filler and polymer. In the case of highly filled composites, the morphology of the PP is important in limiting brittleness and for the strength of the interface between filler and polymer. Surface treatment of the filler has been found to have a significant control over the morphology and properties of the composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1942–1948, 2001     

Influence of talc's morphological characteristics on the toughness of a composite based on low-density polyethylene and polypropylene blends

The toughness of polymer composites based on low-density polyethylene (LDPE)/polypropylene (PP) blends and filled with talcs of different particle size and particle size distribution was studied applying the two-variable Box-Hunter method of optimization. The effect of the polymer matrix composition and percent talc on the Charpy impact strength of the composites, at –30°C, was investigated. The results show a change in the polymer matrix behavior at PP contents of 60% and 75%, depending on talc particle size. At these percentages of PP, toughness exhibits a minimum that becomes lower as the filler content is increased. Optical microscopy shows a nucleating effect of the talc particles for the crystalline polymer. The larger the talc particle size, the higher the nucleation density. The minimum toughness arises at higher PP content in the matrix. At PP contents in the matrix below 35%, the filler has a minimal effect on composite toughness.     

聚丙烯基复合材料的结晶行为

综述了3类聚丙烯(PP)基复合材料体系包括PP/无机物体系、PP/有机物体系和PP／聚合物体系的结晶行为。阐述了PP基体的结晶结构以及结晶动力学特征,包括添加物对PP的结晶温度、结晶速率及结晶度等的影响;分析了结晶行为对复合材料力学性能的影响。复合材料界面对基体聚合物取向结晶形态及结晶行为的影响等还需进一步研究。     

Investigation on Physico-Mechanical Properties,Water, Thermal and Chemical Ageing of Unsaturated Polyester/Turmeric Spent Composites

Nutraceutical industrial residues are potential fillers to fabricate green or eco-friendly polymeric composite materials as they are, less costly and easily available. Attempts have been made to use turmeric spent (TS)—a nutraceutical industry waste with a high E-factor to improve need-based properties of plastics. A series of unsaturated polyester resin composites have been fabricated with different turmeric spent content viz., 5, 10, 15 and 20% w/w. The effect of amount of filler content on tensile strength, physical properties including density and surface hardness and chemical resistance of the composites were determined. The influence of water and thermal ageing on the tensile strength of turmeric filler loaded unsaturated polyester composites has been studied.     

Effect of maleated polypropylene as a compatibilizer and hyperbranched polyester as a processing aid on polypropylene‐wood flour biocomposites

This work focused on two difficulties associated with preparation of polypropylene/wood flour (PP/WF) composites, viz. the compatibility of PP with WF and processing of the composites with high melt viscosity. Maleic anhydride‐grafted polypropylene (MAPP) was used in the preparation of PP composites to provide the compatibility between polymer and filler. Hyperbranched polyester (HBPE) was incorporated to check feasibility of it as a processing aid in the same. The PP/WF composites were formulated by melt compounding on a Brabender Plastograph EC. Blending effect of compatibilizer and processing aid HBPE on PP/WF biocomposites have been carried out on the basis of torque analysis, mechanical properties, morphology, and thermal stability. The investigation showed that HBPE improves the processibility of PP/WF composites than MAPP with respective to torque value. The mechanical and thermal properties slightly vary with change in relative proportion of MAPP and HBPE. J. VINYL ADDIT. TECHNOL., 24:179–184, 2018. © 2016 Society of Plastics Engineers     

Preparation,Characterization, and Dielectric Properties of PP/CaTiO3 Composites for Microwave Substrate Applications

Calcium titanate (CaTiO₃) filled polypropylene (PP) composites have been fabricated through compression molding method. The phase purity of the PP/CaTiO₃ composites was studied using X‐ray diffraction studies. Scanning electron microscopy technique has been employed to study the dispersion of the particulate filler in the PP matrix. The dielectric constant and loss tangent of the composites were measured at X‐band frequency region using waveguide cavity perturbation technique. PP/CaTiO₃ composite has an effective dielectric constant of 11.74 and loss tangent 0.007 at optimum filler loading. The experimental dielectric constant of filled composites was compared with theoretically predicted dielectric constant values obtained using different modeling approaches. The linear coefficient of thermal expansion of PP/CaTiO₃ composites was studied using thermomechanical analyzer.     

Studies on the physico‐mechanical,thermal, and morphological behaviors of high density polyethylene/coleus spent green composites

This study is aimed at utilizing nutraceutical industrial waste and reducing carbon footprints of plastics. Eco‐friendly “green composites” of high density polyethylene (HDPE) were fabricated using coleus spent (CS)—a nutraceutical industrial waste as reinforcing filler and maleic anhydride‐graft‐polyethylene (MA‐g‐PE) as compatibilizer. Composites were fabricated with 5, 10, 15, and 20% (w/w) of CS by extrusion method. The fabricated HDPE/CS composites were evaluated for mechanical and thermal behavior. A slight improvement of about 5% in tensile strength and marked improvement of about 25% in tensile modulus for 20 wt % CS filled HDPE composites was noticed. The effect of CS content on rheological behavior was also studied. Thermal characteristics were performed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA thermogram indicated increased thermal stability of CS‐filled composites. From TGA curves the thermal degradation kinetic parameters of the composites have been calculated using Broido's method. The enthalpy of melting (ΔH_m) obtained from DSC curves was reduced with increase in CS content in HDPE matrix, due to decrease in HDPE content in composite systems. An increase in CS loading increased the water absorption behavior of the composites slightly. Morphological behavior of cryo‐fractured composites has been studied using scanning electron microscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Study of the morphology and mechanical properties of polypropylene composites with silica or rice‐husk

The mechanical, morphological behavior and water absorption characteristics of polypropylene (PP) and silica, or PP and rice‐husk, composites have been studied. The silica used in this study as filler was a commercial type produced from soluble glass or rice husks. The compatibilizing effect of PP grafted with monomethyl itaconate (PP‐g‐MMI) and/or with vinyltriethoxysilane (PP‐g‐VTES) as polar monomers on the mechanical properties and water absorption was also investigated. In general, a high loading of the studied fillers in the polymer matrix increases the stiffness and the water absorption capacity. This effect is more noticeable in the tensile modulus of the PP/silica composite with PP‐g‐VTES as compatibilizer. However, the increase of the rice‐husk charge as a natural filler in the PP matrix decreases the stiffness, and in the presence of PP‐g‐MMI as compatibilizer in PP/rice‐husk, the tensile modulus and water absorption of the composite were improved. The better adhesion and phase continuity in the PP/silica and PP/rice‐husk composites with different compatibilizers was confirmed by the morphological study. Copyright © 2004 Society of Chemical Industry     

Effect of single‐mineral filler and hybrid‐mineral filler additives on the properties of polypropylene composites

The present study was carried out to determine the filler characteristics and to investigate the effects of three types of mineral fillers (CaCO₃, silica, and mica) and filler loadings (10–40 wt%) on the properties of polypropylene (PP) composites. The characteristics of the particulate fillers, such as mean particle size, particle size distribution, aspect ratio, shape, and degree of crystallinity were identified. In terms of mechanical properties, for all of the filled PP composites, Young's modulus increased, whereas tensile strength and strain at break decreased as the filler loading increased. However, 10 wt% of mica in a PP composite showed a tensile strength comparable with that of unfilled PP. Greater tensile strength of mica/PP composites compared to that of the other composites was observed because of lower percentages of voids and a higher aspect ratio of the filler. Mica/PP also exhibited a lower coefficient of thermal expansion (CTE) compared to that of the other composites. This difference was due to a lower degree of crystallinity of the filler and the CTE value of the mica filler. Scanning electron microscopy was used to examine the structure of fracture surfaces, and there was a gradual change in tensile fracture behavior from ductile to brittle as the filler loading increased. The nucleating ability of the fillers was studied with differential scanning calorimetry, and a drop in crystallinity of the composites was observed with the addition of mineral filler. Studies on the hybridization effect of different (silica and mica) filler ratios on the properties of PP hybrid composites showed that the addition of mica to silica‐PP composites enhanced their tensile strength and modulus. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

A study on synergistic reinforcing effect of halloysite nanotubes/diatomite mixture-filled polymer (PP and PA6) composites

In this paper, the nanotubular halloysite nanotubes (HNTs)/disc-shaped diatomite mixture (HD) was used to study the synergistic reinforcing effect of the filler in polymer matrix (PP and PA6). The structure of the HNTs/diatomite mixture filler-filled polymer composites with different proportions of HNTs/diatomite was determined by XRD and SEM. The mechanical performance of the composites was extensively investigated. The results indicated that the HNTs/diatomite mixture filler with different shapes could significantly reinforce the mechanical performance of polymer regardless of whatever it was filled in — PP or PA6. The synergistic reinforcing effect of HNTs/diatomite mixture filler in polymer matrix was verified.     

Compatibilization of polypropylene/molecular sieves type 13X based on carboxyled polypropylene

Molecular sieves type 13X (13X) was selected as a filler of polypropylene (PP). The effect of carboxyled polypropylene (EPP) on mechanical properties, melting behavior, morphology and rheology behavior of PP/13X composites was studied. Mechanical properties tests showed that when 4% EPP added, the impact strength and tensile strength increased 65.6 and 4.6% than PP/13X composites, respectively. It was suggested that the EPP activated the heterogeneous nucleation centers on the filler surface, and made 13X dispersed in PP matrix homogeneously by POM. SEM illustrated that EPP improved the adhesion and the compatibility between 13X and PP. Flow tests indicated that the EPP played the role of lubricant in PP/13X. All the investigations showed EPP was a true coupling agent for PP/13X composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Deformation mechanism of polypropylene composites filled with magnesium hydroxide

The fracture behavior and deformation mechanism of polypropylene (PP) composites filled with magnesium hydroxide [Mg(OH)₂] were investigated. The incorporation of Mg(OH)₂ particles into the PP matrix led to an increase in Young's modulus and a significant reduction in the tensile yield strength and elongation at break. Surface modification on filler particles with stearic acid could reduce the interfacial adhesion between the filler and PP matrix and improve the stress transferability. The deformation mechanism of the Mg(OH)₂/PP composites depended on the interfacial adhesion and the deformability of ligaments between microvoids caused by debonding. The deformability of the ligaments could be significantly improved by surface modification on the particle surface. The dependence of the deformation behavior of the Mg(OH)₂/PP composites on the filler content was in accordance with percolation theory. The agglomeration of microvoids and fibrillation of ligaments in the PP composites with excessive filler content indicated the weak resistance of the polymer matrix to crack propagation and premature fracture in a brittle manner. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1922–1930, 2005     

Crystallization of different polypropylene matrices in the presence of wood fillers

The increasing global energy crisis and ecological risks in recent years have led to the interest in lignocellulosic fillers reinforced polymer composites. In this study, the nucleation ability of pine wood in polypropylene (PP) matrices was studied by differential scanning calorimetry. PPs with different melt flow index values (in range 3.2–25 g/10 min.) were used as the polymer matrix. Moreover, a new technique of wood treatment using γ‐irradiation was used. The experimental results clearly show that the nucleation activity of the wood particles is strongly dependent on the rheological parameter (e.g., MFI) of PP matrix. The composites containing PP matrix with lower MFI exhibited higher degree of crystal conversion, lower half‐times of crystallization, and higher crystallization temperatures. Moreover, the applied γ‐irradiation of wood resulted in a negative effect on the crystallization rate of PP matrix and a distinct deterioration of the nucleation ability of wood surface. The interesting differences in nucleation activity of wood have been interpreted in the context of polymer chains length and relaxation times during crystallization. This article will spotlight the nucleating efficiency of filler, which is critical in polymer processing e.g., optimization of injection molding cycle time of composite materials. POLYM. COMPOS., 36:1813–1818, 2015. © 2014 Society of Plastics Engineers     

Preparation of lightweight and high-strength polypropylene-based ternary conductive polymer foams by in situ microfiber reinforcement

Conductive polymer composites (CPCs) have demonstrated significant potential in the aerospace, electronics, and communications industries. In this study, polypropylene (PP)/multiwalled carbon nanotubes (MWCNTs) binary composites and in situ fiber reinforced multicomposites made from PP/MWCNTs were fabricated by microcellular injection molding. In addition to crystallization behavior, foam morphology, mechanical properties, dielectric properties, and electromagnetic shielding properties of the composites were analyzed. According to the results, microporous structures can facilitate the distribution of conductive fillers, thereby enhancing the electromagnetic shielding performance and mechanical properties of the composite. In situ microfiber networks display a heterogeneous nucleation effect, resulting in an increase in foam density, which improves composite performance. In situ fiber-reinforced microporous multicomposites are capable of exhibiting higher elongation at break and electromagnetic shielding properties than binary systems, and the multicomposites can achieve greater electromagnetic shielding effectiveness (SE) with fewer conductive fillers. Ultimately, fiber-reinforced microporous composites with an elongation at break of 194.40%, an electromagnetic shielding effect of >20 dB, and an absorption mechanism are produced. A feasible method is presented in this study for preparing CPCs that produce light weight, excellent mechanical properties, and high electromagnetic SE at low filler levels.     

Mechanical properties of modified biofiller‐polypropylene composites

This article reports the mechanical, thermal, and morphological properties of polypropylene (PP)‐chicken eggshell (ES) composites. Mechanical properties like tensile strength, tensile modulus, izod impact strength, flexural modulus of PP composites with normal (unmodified) eggshell and chemically treated ES [modified ES (MES) with isophthalic acid] have been investigated. PP–calcium carbonate (CaCO₃) composites, at the same filler loadings, were also prepared and used as reference. The results showed that PP composites with chemically MES had better mechanical properties compared to the unmodified ES and CaCO₃ composites. An increase of about 3–18% in tensile modulus, 4–44% in izod impact strength and 1.5–26% in flexural modulus at different filler loading was observed in MES composites as compared to unmodified ES composites. Scanning electron microscopy (SEM) micrographs of fractured tensile specimens confirmed better interfacial adhesion of MES with polymer matrix resulting into lower voids and plastic deformation resulting in improved mechanicals of the composites. TEM micrographs showed acicular needle shaped morphology for modified ES and have contributed to better dispersion which is the prime reason for enhancement of all the mechanical properties. At higher filler loading, the modulus of MES composite was found to be higher by 5% as compared to commercial CaCO₃ composites. POLYM. COMPOS., 35:708–714, 2014. © 2013 Society of Plastics Engineers     

Studies on thermal behavior,moisture absorption,and biodegradability of ginger spent incorporated polyurethane green composites

Ecological concern on accumulation of neutraceutical industrial waste material and the demands for newer composite materials have promoted extensive research on utilizing industrial wastes materials. Therefore, in the present study finely powdered ginger spent (GS), filled polyurethane (PU) green composites with varying amount viz., 0, 2.5, 5, 7.5, and 10 wt % of GS have been fabricated. The prepared PU/GS green composites have been characterized for their mechanical properties, density and void content. Interaction between filler and matrix has been confirmed from Fourier transform infrared spectroscopy studies. Moisture absorption and desorption studies have been performed at different relative humidity (RH). The moisture absorption and desorption studies, shows that as the hydrophilic GS content increases in the matrix the RH also increases. Water uptake behavior of PU/GS were measured in different chemical environments such as 5% sodium chloride solution, cold water at different temperature and in hydrochloric acid solution. The water uptake values increases as increase in GS concentration. Equilibrium water content, diffusivity and equilibrium time taken for all PU/GS composites have been investigated. Biodegradation studies reveals that as the GS content increases the weight loss also increases. Thermal properties have been performed using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). From DSC and DMA thermograms it is revealed that increase in T_g with increase in GS content. RH and contact angle measurement have been performed to understand the hydrophilic nature of the prepared composite. The morphological behavior of composites has been studied using scanning electron microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41614.     

Crosslinkable polypropylene composites made by the introduction of silane moieties

Silane‐crosslinkable polypropylene (PP) composites containing calcium carbonate (CaCO₃) as a filler have been investigated. The melt grafting of vinyl trimethoxysilane to PP with dicumyl peroxide (DCP) as a radical initiator is demonstrated. The thermal and mechanical properties of the crosslinkable products are also discussed. The results show that two reactions, that is, silane grafting and PP degradation, take place in parallel. The extents of silane grafting and PP degradation strongly depend on the reaction temperature, grafting formulation, and amount of the filler in the systems. Increasing the DCP concentration (up to 0.05 wt %) leads to an increase in the grafting degree. However, when the concentration of radicals is over a certain degree, the dominant reaction is PP chain scission. This results in a drastic decrease in the polymer viscosity. In systems containing both silane and CaCO₃, the viscosity of the polymer is higher than that of a grafted sample without CaCO₃ addition; in other words, the effect of the filler on the polymer viscosity compensates for the effect caused by PP degradation. Differential scanning calorimetry results show that the crystallization starts earlier for grafted samples. The percentage of the crystallinity of grafted PP is higher than that of the pure polymer. The incorporated silane does not have a strong effect on the mobility of the PP chains, as revealed by dynamic mechanical analysis. In comparison with ungrafted composites, the silane‐crosslinkable products show higher tensile stress and modulus. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1476–1483, 2005     

Processing and characterization of injection moldable polymer–particle composites applicable in brazing processes

A novel method has been developed to process highly filled polymer–particle composites to test samples as braze metal preforms. Polypropylene (PP), low‐density polyethylene (LD‐PE) and high‐density polyethylene (HD‐PE) were used as polymer matrices. Two types of nickel‐based braze metal microparticles (Ni 102 and EXP 152) were compounded to the polymer matrices at filler contents up to 65 vol %. With enhancing filler content, torque at kneading rotors, and injection molding parameter were significantly affected by increasing viscosity. Injection molded composites show well‐distributed spherical microparticles and particle–particle interactions. Polymers decompose residue‐free at temperatures above 550°C, even for their composites. Adding particles reduces polymer crystallinity, whereas defined cooling at 5°C/min significantly increases the crystallinity and melt peak temperature of polymers compared to undefined cooling prior injection molding. Storage modulus of polymers increases significantly by adding filler particles. LD‐PE + 65 vol % EXP 152 show the most suitable composite performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Nonisothermal crystallization kinetics of polypropylene‐layered double hydroxide composites: Correlation with morphology

In this work the effect of nanofiller on nonisothermal crystallization behavior of composites based on polypropylene (PP) was investigated by differential scanning calorimetry. The materials were prepared by melt mixing. Both an alkyl sulfonate salt modified layered double hydroxide (LDH) and an unmodified LDH were used as nanofillers and both PP and PP/polypropylene grafted with maleic anhydride (PP‐g‐MA) blend were used as matrices. The morphology of composites was investigated by X‐ray diffraction and transmission electron microscopy. No exfoliation was noticed in all prepared composites, but the hybrid materials showed an intercalated structure. The thermal properties and crystallization behavior were studied by conventional differential scanning calorimetry. In particular, the kinetic crystallization parameters were obtained using the modified Avrami equation for a nonisothermal process, whereas the activation energy of the global crystallization process was estimated using the Kissinger equation. The Avrami parameters suggest a significant effect on the crystallization of PP for the composites containing both the organically modified LDH and PP‐g‐MA. The results indicate a complex crystallization process of PP and evidence that the crystallization process can not be only explained by intercalation phenomenon, but the constrain effect ofpolymer chains on the filler surface and/or betweenthe filler clusters should play a significant role. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers