Ethylene/silane copolymers prepared with a metallocene catalyst as polymeric additives in polyethylene/aluminum trihydroxide composites

Metallocene catalyst based polyethylene‐co‐7‐octenyldimethyl phenyl silane (PE/Si? Ph ) and its post‐treated functional forms PE/Si? X ( X = Cl , F , OCH₃ , OCH₂CH₃ ) were used as additives in PE/ATH composites. The impact strength of the composites was significantly increased after a small addition (0.5–3.0 wt %) of the functionalized form of the copolymer (PE/Si? X ). The thermal study of the composites gave us more information about the additive's behavior at the filler/matrix interphase and correlation to the mechanical properties was found. According to this thermal data, the original untreated form of PE/Si? Ph also seemed to interact weakly with the ATH‐filler particles, which was seen in an altered interphase at the filler/matrix boundary layer. The interaction was not strong enough to improve the impact strength of composites but an increase was observed in some other mechanical properties (tensile stress, yield strain). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5597–5608, 2005     

Preparation and enhanced properties of poly(propylene)/ silica‐grafted‐hyperbranched polyester nanocomposites

A series of poly(propylene) silica‐grafted‐hyperbranched polyester nanocomposites by grafting the modified hyperbranched polyester (Boltorn? H20), possessing theoretically 50% end carboxylic groups and 50% end hydroxyl groups, which endcapped with octadecyl isocyanate (C19), onto the surface of SiO₂ particles (30 nm) through 3‐glycidoxy‐propyltrimethoxysilane (GPTS) was prepared. The effect of silica‐grafted‐modified Boltorn? H20 on the mechanical properties of polypropylene (PP) was investigated by tensile and impact tests. The morphological structure of impact fracture surface and thermal behavior of the composites were determined by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The melt viscosity of composites was investigated by melt flow index (MFI). The obtained results showed that: (1) the modified Boltorn? H20 was successfully grafted onto the SiO₂ surface confirmed by FT‐IR and X‐ray photoelectron spectroscopy (XPS) analysis; (2) the incorporation of silica‐grafted‐modified Boltorn? H20 (3–5 wt% SiO₂) greatly enhanced the notched impact strength as well the tensile strength of the composites; (3) the incorporation of silica‐grafted‐modified Boltorn? H20 had no influence on the melting temperature and crystallinity of PP phase; (4) the MFI of PP composites increased when the silica‐grafted‐modified Boltorn? H20 particles were added compared with PP/SiO₂ or PP/SiO₂‐GPTS composites. Copyright © 2004 John Wiley & Sons, Ltd.     

The influence of CaCO3 filler component on thermal decomposition process of PP/LDPE/DAP ternary blend

Polypropylene‐low density polyethylene (PP‐LDPE) blends involving PP‐LDPE (90/10 wt%.) with (0.06 wt%) dialkyl peroxide (DAP) and different amounts (5, 10, 20 wt%) of calcium carbonate (CaCO₃) were prepared by melt‐blending with a single‐screw extruder. The effect of addition of CaCO₃ on thermal decomposition process and kinetic parameters, such as activation energy and pre‐exponential factor of PP‐LDPE blend with DAP matrix, was studied. The kinetics of the thermal degradation of composites was investigated by thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. TG curves showed that the thermal decomposition of composites occurred in one weight‐loss stage. The apparent activation energies of thermal decomposition for composites, as determined by the Tang method (TM), the Kissinger–Akahira–Sunose method (KAS), the Flynn–Wall–Ozawa method (FWO), and the Coats–Redfern (CR) method were 156.6, 156.0, 159.8, and 167.7 kJ.mol^?1 for the thermal decomposition of composite with 5 wt% CaCO₃, 191.5, 190.8, 193.1, and 196.8 kJ.mol^?1 for the thermal decomposition of composite with 10 wt% CaCO₃, and 206.3, 206.1, 207.5, and 203.8 kJ mol^?1 for the thermal decomposition of composite with 20 wt% CaCO₃, respectively. The most likely decomposition process for weight‐loss stages of composites with CaCO₃ content 5 and 10 wt% was an A_n sigmoidal type. However, the most likely decomposition process for composite with CaCO₃ content 20 wt% was an R_n contracted geometry shape type in terms of the CR and master plots results. It was also found that the thermal stability, activation energy, and thermal decomposition process were changed with the increase in the CaCO₃ filler weight in composite structure. Copyright © 2009 John Wiley & Sons, Ltd.     

Solvothermal synthesis of WO3/TiO2/carbon fiber composite photocatalysts for enhanced performance under sunlight illumination

Carbon fiber (CF)‐based WO₃/TiO₂ composite catalysts (WO₃/TiO₂/CF) were successfully synthesized by solvothermal method. The catalysts were characterized by XPS, SEM, BET, XRD, FTIR, Raman and UV–Vis. The analyses confirmed the WO₃/TiO₂ nanoparticles with high crystallinity deposited on the carbon structure. The photocatalytic degradation of Orange II azo dye under UV and sunlight illumination with the synthesized catalyst was explored. The composite catalyst displayed high performance (85%) for Orange II degradation while that of for WO₃/TiO₂ was found as 76%. The effects of CF amount, solution pH, initial dye concentration and catalyst dose on photocatalytic performance were studied. It was found that the degradation efficiency increased from 68% to 90% with the increasing CF amount from 3 wt% to 5 wt%, while the further increase in CF amount (7–10 wt%) decreased the photodegradation due to the blocking the active sites of WO₃/TiO₂. The enhanced photocatalytic efficiency was mainly attributed to the electrical properties of the CF and reduced bandgap.     

Mechanical,Thermal and Morphological Behaviors of Castor Oil Based PU/PS Interpenetrating Polymer Network-Metakaolin Composites

The meta kaolin (MK) clay particulate filler with different weight ratios viz., 0, 5, 10, 20 and 30 wt% were incorporated into castable polyurethane (PU)/polystyrene (PS) (90/10) interpenetrating polymer network (IPN). The effects of MK particulate filler loading on the mechanical and thermal properties of PU/PS (90/10) IPN composites have been studied. From the tensile behavior, it was noticed that a significant improvement in tensile strength and tensile modulus as an increase in MK filler content. Thermogravimetric analysis (TGA) data reveals the marginal improvement in thermal stability after incorporation of MK filler. TGA studies of the IPN composites have been performed in order to establish the thermal stability and their mode of thermal degradation. It was found that degradation of all composites takes place in two steps. Degradation kinetic parameters were obtained for the composites using three mathematical models. Tensile fractured composite specimens were used to analyze the morphology of the composites by scanning electron microscopic (SEM) technique.     

Polylactide compositions. II. Correlation between morphology and main properties of PLA/calcium sulfate composites

Starting from calcium sulfate (gypsum) as fermentation by‐product of lactic acid production process, high performance composites have been produced by melt‐blending polylactide (PLA, L/D isomer ratio of 96:4) and β‐anhydrite II (AII) filler, that is, calcium sulfate hemihydrate previously dehydrated at 500 °C. Characterized by attractive mechanical and thermal properties due to good filler dispersion throughout the polyester matrix, these composites are interesting for potential use as biodegradable rigid packaging. Physical characterization of selected composites filled with 20 and 40 wt % AII has been performed and compared to processed unfilled PLA with similar amorphous structure. State of dispersion of the filler particles and interphase characteristic features have been investigated using light microscopy (LM) and scanning electron microscopy (SEM). Addition of AII did not decrease PLA thermal stability as revealed by thermogravimetry analyses (TGA) and allowed reaching a slight increase of PLA crystallizability during melt crystallization and upon heating from the glassy, amorphous state (DSC). It was found by thermomechanical measurements (DMTA) that the AII filler increased pronouncedly storage modulus (E′) of the composites in comparison with PLA in a broad temperature range. The X‐ray investigations showed stable/unchanged crystallographic structure of AII during processing with molten PLA and in the composite system. The notable thermal and mechanical properties of PLA–AII composites are accounted for by the good filler dispersion throughout the polyester matrix confirmed by morphological studies, system stability, and favorable interactions between components. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2770–2780, 2007     

Investigation of sub‐micron size cenosphere fillers and filler loading on the mechanical and tribological peculiarity of polyester composites

This paper investigates the effect of sub‐micron size cenosphere filler and filler loading on mechanical and dry sliding wear property of polyester composites. Composites are fabricated by filling with 10 and 20 wt% of 800 and 200‐nm size of cenosphere filler particles. Neat polyester composite is also prepared for comparison analysis. Dry sliding wear test is conducted for these composites over a range of sliding distance with different sliding velocities and applied loads on a pin‐on‐disc wear test machine. Taguchi methodology and analysis of variance (ANOVA) is used to analyze the friction and wear characteristics of the composites. The artificial neural network (ANN) approach is implemented to the friction and wear data for corroboration. In this work, mechanical properties of composites such as hardness, tensile strength, tensile modulus, flexural strength, and compressive strength revealed that mechanical properties and wear resistance of the composites increase with a decrease in the particle size. The measured Young's moduli are comparable to standard theoretical prediction models. The morphology of worn composite specimens has been examined by scanning electron microscopy to understand the dominant wear mechanisms. Finally, optimal factor settings are determined using a genetic algorithm (GA). Copyright © 2017 John Wiley & Sons, Ltd.     

Polylactide (PLA) and Highly Filled PLA - Calcium Sulfate Composites with Improved Impact Properties

Summary: Starting from gypsum as by-product of lactic acid fabrication process, novel high performance composites have been produced by melt-blending PLA and this filler after a previous specific dehydration performed at 500 °C for min. 1h. Due to PLA sensitivity towards hydrolysis, the utilization of β-anhydrite II (AII) as filler is a prerequisite. Characterized by attractive mechanical and thermal properties due to good filler dispersion throughout the polyester matrix, these composites are interesting in biodegradable rigid packaging or technical applications. Interestingly, tensile strength of PLA – AII composites proved remarkably high, e.g. higher than 35 MPa at 50 wt-% filler content. However a decrease of impact properties has been recorded. To increase the toughness of these composites while preserving high stiffness an impact modifier based on ethylene copolymer has been mixed with both the polymer matrix and AII by melt-compounding. The effectiveness of the impact modifier was confirmed in both neat PLA and AII-based composites. Addition of 5-10 wt-% impact modifier into highly filled composites (30 to 40 wt-% filler) leads to an attractively threefold increase of impact strength with respect to the compositions without modifier, remarkable thermo-mechanical performances and good filler dispersion.     

Synthesis and Characterization of Polyester-Based Nanocomposite

Recently, unsaturated polyester resin (UPR) and silica nanocomposite prepared by mechanical process is the one of the promising composite materials. In this study, the effects of silica as filler on mechanical, thermal, and morphological properties of unsaturated polyester-based composite were investigated. Mechanical properties such as tensile strength, elongation and Young's modulus increase with the addition of silica nanoparticle up to 1.0 wt%, and then decrease, over 1.0 wt%. Morphological surface of composite reveals that well-dispersed silica in the matrix occurred in low concentration. However, increasing of silica concentration causes aggregation of particles. Enhancement of mechanical properties strongly corresponds to strong adhession force of silica with the matrix and it influnced by well-disperse silica particles on the whole surface of composite. Thermal characterization and analysis of major functional group of the composites were also performed and described in this paper.     

Effect of hybrid fillers on the mechanical behavior of polypropylene based hybrid composites

The present study investigates the effect of hybrid fillers such as graphene nanoplatelets (GnPs) and Titanium di-oxide (TiO₂) in polypropylene (PP) composites on the mechanical properties. The compatibilizing agent of Maleic anhydride grafted polypropylene (MAPP) are used in the polypropylene based composites to increase the interfacial adhesion between matrix and fillers. The experiments are designed according to L₁₆ orthogonal array (OA) based design of experiments (DOE). The parameters selected for this study are GnPs, TiO₂ and MAPP with four different levels are used.By using Orthogonal array and Taguchi based experimental design, the performance characteristics of tensile modulus, tensile strength, elongation at break and toughness can be analyzed with more objective through a small set of experiments.Taguchi based analysis are used to find out the optimal parameters to maximize the tensile properties for the GnPs and TiO₂ reinforced PP hybrid composites. Further, analysis of variance (ANOVA) is investigated to identify the most significant parameters which influence the mechanical properties.From the analysis it was found that the optimal parameters of 3 ?wt% GnPs, 2 ?wt% TiO₂ and 6 ?wt% MAPP for maximum tensile modulus and tensile strength. The most significant parameter for tensile modulus and tensile strength is GnPs followed by TiO₂ and MAPP according to ANOVA analysis.     

Synthesis,characterization, and visible light–induced photocatalytic evaluation of WO3/NaNbO3 composites for the degradation of 2,4-D herbicide

In this research study, WO₃/NaNbO₃-coupled photocatalysts were synthesized at three WO₃ mass ratios (15, 85, and 95 wt%) and characterized. These composites were characterized via X-ray powder diffraction, N₂ physisorption, UV–Vis diffuse reflectance spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and photoluminescence techniques. For comparison, bare WO₃ and NaNbO₃ were also synthesized and characterized. 2,4-Dichlorophenoxyacetic acid (2,4-D) was degraded under visible light to evaluate its photocatalytic performance. The WO₃ (95 wt%)/NaNbO₃ composite showed higher photocatalytic activity than pure WO₃ and NaNbO₃ and even than the 15 and 85 wt% coupled materials; thus, the combination with the highest ratio of WO₃ with respect to NaNbO₃ showed increased photocatalytic activity compared with the bare materials.     

Thermal properties of microcrystalline cellulose-filled PET–PTT blend polymer composites

Polymer composite materials were prepared from poly(ethylene terephthalate)–poly(trimethylene terephthalate) blends as the matrix and different microcrystalline cellulose (MCC) filler levels (0–40 wt%) using melt compounding followed by compression molding. The composites were analyzed using dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The DSC results indicated that there is no consistent or significant influence of the MCC addition on the glass transition (T _g), melting (T _m), and crystallization temperature of the composites. With increasing MCC content, dynamic mechanical properties improved because of the reinforcing effect of the MCC. The tan δ peak values from the DMTA were not significantly changed as the MCC content increased. TG indicated that the onset temperature of rapid thermal degradation decreased with increasing MCC content. It was also found that the thermal stability of the composites slightly decreased as the MCC content increased.     

Thermal degradation of Pb(Zr0.53Ti0.47 )O3/poly(vinylidene fluoride) composites as a function of ceramic grain size and concentration

Poly(vinylidene fluoride)/Pb(Zr_0.53Ti_0.47)O₃,([PVDF]_1?x/[PZT]_x) composites of volume fractions x and (0–3) type connectivity were prepared in the form of thin films. PZT powders with average grain sizes of 0.2, 0.84, and 2.35 μm in different volume fraction of PZT up to 40 % were mixed with the polymeric matrix. The influence of the inorganic particle size and its content on the thermal degradation properties of the composites was then investigated by means of thermo-gravimetric analysis. It is observed that filler size affects more than filler concentration the degradation temperature and activation energy of the polymer. In the same way and due to their larger specific area, smaller particles leave larger solid residuals after the polymer degradation. The polymer degradation mechanism is not significantly modified by the presence of the inorganic fillers. On the other hand, an inhibition effect occurs due to the presence of the fillers, affecting particularly the activation energy of the process.     

Effects of nano ZnO on strength and stability of unsaturated polyester composites

ZnO–glass fiber–unsaturated polyester composites have been prepared. On exposure to the metal halide lamp, their resistance to ultraviolet (UV) degradation is evaluated. Experimental results show that ZnO can reduce the UV degradation of the unsaturated polyester matrix. ZnO can significantly retard the UV degradation process of the matrix resin, and can also increase the impact strength of the composites under the experimental conditions. Differential scanning calorimetry (DSC) analyses also indicate that the addition of ZnO to unsaturated polyester may retard the crosslink process and catalyze the decomposition of the resin. However, after more than 40 hr of UV irradiation, it was crosslinked. SEM fracture morphology shows that nano ZnO could hinder crack growth and induce more cracks, and when the content of ZnO reaches 6 wt%, the impact fracture mechanism changes abruptly and plastic deformation appears, which indicates that 6 wt% for ZnO in unsaturated polyester could be considered as the critical content. Around the critical content, the particles are near enough to interact with each other and this results in the change of fracture mechanism. The results also indicate that the proper content of ZnO added into an unsaturated polyester could prolong the durability and lessen the reject rate of transparent glass fiber–polyester composites. Copyright © 2008 John Wiley & Sons, Ltd.     

Mechanical and morphological properties of injection-molded rice husk polypropylene composites

In this work, the investigation of the physical, mechanical, and morphological properties of the rice husk flour/polypropylene composites was performed utilizing various filler loadings and coupling agent. Five levels of filler loading (35, 40, 45, 50, and 55 wt%) were designed. In addition, to help the interaction between fiber and polypropylene matrix, struktol coupling agent was added to the composites. All of tensile strength, Young's modulus, flexural strength, flexural modulus, and impact strength properties of the composites were carried out. Moreover, the 50 wt% filler-loaded composites had optimum tensile strength, flexural strength, and flexural modulus, whereas the 35 wt% of filler loading case was the best regarding Young's modulus, flexural strength, flexural modulus, and impact strength. Furthermore, the scanning electron microscope results demonstrate that as filler loading increases, more voids and fiber pullout occur.     

Effect of CaCO3 Filler Component on Solid State Decomposition Kinetic of PP/LDPE/CaCO3 Composites

In this study, the effect of addition Calcium carbonate (CaCO₃) filler component on solid state thermal decomposition procedures of Polypropylene-Low Density Polyethylene (PP-LDPE; 90/10 wt%) blends involving different amounts (5, 10, 20 wt%) Calcium carbonate (CaCO₃) was investigated using thermogravimetry in dynamic nitrogen atmosphere at different heating rates. An integral composite procedure involving the integral iso-conversional methods such as the Tang (TM), the Kissinger-Akahira-Sunose method (KAS), the Flynn-Wall-Ozawa (FWO), an integral method such as Coats-Redfern (CR) and master plots method were employed to determine the kinetic model and kinetic parameters of the decomposition processes under non-isothermal conditions. The Iso-conversional methods indicated that the thermal decomposition reaction should conform to single reaction model. The results of the integral composite procedures of TG data at various heating rates suggested that thermal processes of PP-LDPE-CaCO₃ composites involving different amounts of CaCO₃ filler component (5, 10, 20 wt%) followed a single step with approximate activation energies of 226.7, 248.9, and 252.0 kJ.mol^{? 1} according to the FWO method, respectively and those of 231.3, 240.1 and 243.0 kJ mol^{? 1} at 5°C min^{? 1} according to the Coats-Redfern method, the reaction mechanisms of all the composites was described from the master plots methods and are P_n model for composite C-1, R_n model for composites C-2 and C-3, respectively. It was found that the thermal stability, activation energy and thermal decomposition process changed by the increasing CaCO₃ filler weight in composite structure.     

Preparation and characterization of graphite nano-platelet (GNP)/epoxy nano-composite: Mechanical,electrical and thermal properties

Epoxy based polymer nano-composite was prepared by dispersing graphite nano-platelets (GNPs) using two different techniques: three-roll mill (3RM) and sonication combined with high speed shear mixing (Soni_hsm). The influence of addition of GNPs on the electrical and thermal conductivity, fracture toughness and storage modulus of the nano-composite was investigated. The GNP/epoxy prepared by 3RM technique showed a maximum electrical conductivity of 1.8 × 10⁻⁰³ S/m for 1.0 wt% which is 3 orders of magnitude higher than those prepared by Soni_hsm. The percentage of increase in thermal conductivity was only 11% for 1.0 wt% and 14% for 2.0 wt% filler loading. Dynamic mechanical analysis results showed 16% increase in storage modulus for 0.5 wt%, although the Tg did not show any significant increase. Single edge notch bending (SENB) fracture toughens (K_IC) measurements were carried out for different weight percentage of the filler content. The toughening effect of GNP was most significant at 1.0 wt% loading, where a 43% increase in K_IC was observed. Among the two different dispersion techniques, 3RM process gives the optimum dispersion where both electrical and mechanical properties are better.     

High thermal conductivity polylactic acid composite for 3D printing: Synergistic effect of graphene and alumina

With the continuous development of the electronics industry, in order to meet the requirements of electronic equipment to reduce the size and increase power consumption, the development of high thermal conductivity materials is crucial. In this study, thermally conductive polylactic acid (PLA) composites were prepared by constructing graphene and alumina (Al₂O₃) hybrid filler network, and it was further successfully used in additive manufacturing. Due to the synergistic effect of Al₂O₃ and graphene, the resulting composite achieved the thermal conductivity of 2.4 Wm^?1 K^?1 with 70 wt% Al₂O₃ and 1 wt% graphene, which are superior to data reported in the literature in the same filler condition. The Al₂O₃ and graphene hybrid filler network reduced the agglomeration of graphene and the thermal contact resistance between the fillers, thereby leading a faster cooling rate. Furthermore, the obtained thermally conductive PLA composite has good thermal stability at a normal temperature. The PLA composite powder obtained by the cryogenic pulverization can be used in the laser sintering additive manufacturing process to prepare a heat conductive material with a complicated shape.     

Investigating the mechanical,thermal and melt flow index properties of HNTs – LLDPE nano composites for the applications of rotational moulding

Linear low density polyethylene (LLDPE) is the one of the most popular polymer used for rotational moulding applications such as storage tanks. But, its inferior mechanical properties and thermal stability restrict the longer service. Hence, this study experimentally demonstrates the effect of Halloysite Nanotube (HNTs) concentration on LLDPE composites for enhancing the mechanical and thermal stability. HNTs were uniformly dispersed with LLDPE matrix through ultra-sonication, followed by compression moulding used to prepare the nano composites plates. The prepared composites are shown 19.2% improved tensile strength for 2 wt% HNTs, whereas 28.9% hike in flexural strength observed for 4 wt% HNTs composite, compare to neat LLDPE. Which shows that higher concentrations of HNTs is favourable in improving the flexural strength rather than tensile properties. In addition to that, higher concentrations of HNTs are also helping in improving the storage modulus of the LLDPE composites. The increase in mechanical properties mainly attributed due to effective load carriers (HNTs) in the composite. Besides, HNTs were also contributing for improving the melting point and residual char of the composites, which is indeed for storage tanks durability. The prepared composite was thermally stable at higher temperature up to 230 °C, because of HNTs chemical structure, the inner layer of HNTs constitute with Al₂O₃ and outermost layer constitute with SiO_2, both are thermally stable. Stated enhancement proves the potential effect of HNTs reinforcement in the LLDPE composite for rotational moulding applications.     

Conductivity of composite materials based on Me2(WO4)3 and WO3 (Me = Sc,In)

Composites {Me₂(WO₄)₃ ? xWO₃} (Me = Sc, In) (x = 0.5–99%) are synthesized and characterized by XRD and electron microscopy methods and also by the density and specific surface measurements. Temperature dependences of the total conductivity of composites are measured. The contributions of σ_tot and σ_el are assessed by the $\sigma (a_{O_2 } )$ and EMF methods. The concentration dependences of conductivity and activation energy are plotted based on the σ_tot and σ_ion data. It is shown that (a) in the interval x = 0–30 vol % WO₃ (0–70 mol %), the conductivity is independent of composition and the ionic component prevails; (b) in the interval x = 60–94.5 vol % (90–99 mol %), the electron conductivity prevails and increases with the increase in x; (c) in the x interval of 30–60 vol % WO₃ (70–90 mol %), the conductivity is mixed, i.e., electron(n-type)-ionic; the latter region represents the transition interval from ionic to electron conductivity as x increases. These data are compared with the results obtained earlier for MeWO₄-WO₃ composites (Me = Ca, Sr, Ba). As regards the structural topology, the {Me₂(WO₄)₃ ? xWO₃} composites pertain to the randomly distributed type. It is shown that in contrast to {Me^IIWO₄ · xWO₃} composites, the composites under study do not form the nonautonomous interface phase with the high ionic conductivity. The possible reasons for the observed differences in the topology and the conduction type of composites based on MeWO₄ and Me₂(WO₄)₃ are analyzed.