Mechanical properties and fracture morphology of Al(OH)3/polypropylene composites modified by PP grafting with acrylic acid

Al(OH)₃/polypropylene (PP) composites modified by polypropylene grafted with acrylic acid (FPP) were prepared by melt extrusion. Effect of PP grafting with acrylic acid on mechanical properties and fracture morphology of Al(OH)₃/polypropylene composites were investigated. Although incorporation of Al(OH)₃ reduced the mechanical properties of PP, addition of FPP increased the mechanical properties of Al(OH)₃/PP composites. It is suggested that addition of FPP improve the dispersion of Al(OH)₃ and the interfacial interaction between filler and matrix. Mechanical properties of Al(OH)₃/FPP/PP composites depend on the grafting rate and the content of FPP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2617–2623, 2001     

Comparison of the mechanical properties and interfacial interactions between talc,kaolin, and calcium carbonate filled polypropylene composites

Three types of mineral fillers—talc, calcium carbonate (CaCO₃), and kaolin (10–40 wt % filler loadings)—were compounded with polypropylene (PP) with a twin‐screw extruder. The composites were injection‐molded, and the effects of the filler loading on the mechanical, flow, and thermal properties for the three different types of filled composites were investigated. The aim was to compare their properties and to deduce prospective filler combinations that would yield hybrid PP composites in following studies. The results showed that in most cases, the strength and stiffness of the talc‐filled PP composites was significantly higher than those of the CaCO₃‐ and kaolin‐filled PP composites. However, CaCO₃, being a nonreactive filler, increased the toughness of PP. The kaolin‐filled PP composites also showed some improvement in terms of strength and stiffness, although the increases in these properties were not as significant as those of the talc‐filled PP composites. The effects of interfacial interactions between the fillers and PP on the mechanical properties were also evaluated with semiempirical equations. The nucleating ability of all three fillers was studied with differential scanning calorimetry, and the strongest nucleating agent of the three was talc, followed by CaCO₃ and kaolin. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3315–3326, 2004     

Thermal stability and mechanical properties of room temperature vulcanized silicone rubbers

Based on much of the importance of RTV on the field of self-cleaning application for its nontoxic, tasteless, and thermal stability, the effects of D₄-SiO₂ on mechanical properties, Al(OH)₃ and decabromodiphenyl oxide ethyl(DBDPE) on flame retardant property of RTV matrix were investigated firstly. Then, a new kind of complex fire retardants was compounded. The morphology of additives and fracture appearance of composites were demonstrated by SEM. The hot property of RTV-based composites was outlined by TG. It is found that D₄-SiO₂/Al(OH)₃/DBDPE/Sb₂O₃/RTV composites were of better comprehensive performances in mechanical property, hot property, fire resistance property, and insulating property, which presented tear 26.73 kN/m of strength, 279.8% of elongation at break, 2.81 MPa of tensile strength, FV-0 at the level of flame retardant property, 46 of Oxygen index (OI) 3.03 × 10¹⁵ Ωm of Volume electric resistivity, the range of decomposition temperature was 370°C to 650°C, and the percentage of remain weight was 26.4%. Those properties was acquired on the condition of 11 wt % D₄-SiO₂ + 20 wt % Al(OH)₃ + 15 wt % DBDPE+ Sb₂O₃ at the amount of 3.0 wt % to 3.7 wt %. This investigation leads the authors to a conclusion that D₄-SiO₂/Al(OH)₃/DBDPE/Sb₂O₃ is a kind of better combination modifier than anyone kind of which in comprehensive properties for RTV. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Physical and mechanical properties of Al(OH)3/polypropylene composites modified by in situ‐functionalized polypropylene

Al(OH)₃/polypropylene (PP) composites modified by in situ‐functionalized polypropylene (FPP) were prepared by a one‐step melt‐extrusion process. The effect of in situ FPP on the crystallization and melting behavior, melt‐flow index, limiting oxygen index, thermal degradation, mechanical properties, and fracture morphology of Al(OH)₃/PP composites was studied. Formation of in situ FPP resulted in a decreased crystallization temperature and melting point of PP in the composites, an increased melt‐flow index, and improved tensile and flexural strengths of Al(OH)₃/PP composites, whereas the thermal degradation behavior and limiting oxygen index was not been influenced. The impact strength of the Al(OH)₃/PP composites modified by in situ FPP depended upon the content of the initiator, dicumyl peroxide, and the monomer, acrylic acid. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2850–2857, 2002; DOI 10.1002/app.10269     

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     

Preparation and characterization of nano/micro‐calcium carbonate particles/polypropylene composites

A new kind of polypropylene (PP)/CaCO₃ composites was prepared on a twin screw extruder with the nanoparticle content of 5 wt % and the 2500 mesh microparticle content of 15 wt %. The mechanical property of four different samples [pure PP (1) , PP filled with 15 wt % microCaCO₃ particle composites (2) , PP filled with 5 wt % nanoCaCO₃ particle composites (3) and PP filled with micro/nano‐CaCO₃ complex size particle composites (4) ] was investigated through tensile tests, notched Izod impact tests and SEM. The results indicated that the sample 4 had the best mechanical property. The proofs of SEM showed that the high impact energy could lead to debonding and creating microcavitation between the nanoparticle and polymer interface if the polymer was filled with the nanoparticles. This process could absorb a lot of mechanical failure energy, but too much mechanical failure energy would lead to the enlargement of microcavitation and the destruction of the composites in sample 3 . In sample 4 , the microparticle could be used to prevent the enlargement of microcavitation in the matrix polymer under the higher impact failure energy. In this article, the model of the impacting failure process of micro/nanoCaCO₃/PP composites was established. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of silicone oil and polymeric modifiers on the mechanical properties of highly filled LLDPE

The effects of coupling agents, silicone oil, and three types of polymeric modifiers on the mechanical properties of linear low density polyethylene (LLDPE) composites highly filled with aluminium hydroxide [Al(OH)₃] were studied. Polymeric modifiers that contain polar groups, such as silane‐grafted polyethylene (Si‐g‐PE) and acrylic‐acid‐grafted ethylene‐vinyl acetate copolymer (AA‐g‐EVA), improve the mechanical properties dramatically, while nonpolar modifiers improve them to some extent. When Al(OH)₃ was treated using a titanate coupling agent, the silicone oil increased the impact strength and elongation at break of the LLDPE/Al(OH)₃ composites. Introduction of a polymeric modifier containing polar groups destroys the beneficial effects of silicone oil on film mechanical properties, while the introduction of a nonpolar elastomeric polymeric modifier retains the high impact strength and elongation at break. SEM analyses provide the indirect evidence of the encapsulation of silicone oil around the filler. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 121–128, 2002     

Characterization of PP/Mg(OH)2 and PP/Nanoclay Composites with Supercritical CO2 (scCO2)

In this article, supercritical carbon dioxide (scCO₂) is used to form a high density microcellular foam structure to reduce the polymer use and facilitate dispersion of Mg(OH)₂ and Nanoclay fillers. A twin-screw extruder system was used to predistribute the inorganic filler from the PP polymer, resulting composite PP/filler pellets. This followed by the use of a single-screw extruder wherein supercritical carbon dioxide is introduced in the formulation. Finally the resulting foam PP/filler/CO₂ pellets are injection molded into test samples. The structure and properties of the composites are characterized using a scanning electron microscopy (SEM), Differential scanning calorimetry (DSC), and density measurements. Furthermore, PP/Clay/Mg(OH)₂ polymer composites are subjected to examinations to obtain their yield and tensile strengths, elasticity modulus, % elongation, Izod impact strength, hardness, Heat deflection temperature (HDT), Vicat softening point and Melt flow index (MFI).     

A study of the flame‐retardant properties of polypropylene/Al(OH)3/Mg(OH)2 composites

Polymeric materials are used extensively, but their applications are limited because many of them are flammable. Therefore ways to make them flame retardant have received much attention. In this work, polypropylene (PP) was used as the matrix resin, aluminium hydroxide (Al(OH)₃) and magnesium hydroxide (Mg(OH)₂) as flame‐retardant additives and zinc borate (ZB) as a flame‐retardant synergist. PP/Al(OH)₃/Mg(OH)₂ and PP/Al(OH)₃/Mg(OH)₂/ZB flame‐retardant composites were prepared with a twin‐screw extruder. The flame‐retardant properties, i.e. oxygen index (OI), burning velocity and smoke density, of the composites were measured. The results showed that OI increased with an increase of the filler content and decreased with an increase of the filler particle diameter. The burning velocity decreased with an increase of the filler content, while it first increased and then decreased with an increase of the filler particle diameter. The smoke density decreased with an increase of the filler content and increased with an increase of the filler particle diameter. There was a flame‐retardant synergy between Al(OH)₃/Mg(OH)₂ and ZB in the composites, and the smoke suppression effect was marked when ZB was added. Copyright © 2009 Society of Chemical Industry     

Effect of fillers and additives on the properties of SBR vulcanizates

Methacrylic acid (MAA) and methyl methacrylate (MMA) were used as additives for peroxide‐cured styrene–butadiene rubber (SBR) filled with three inorganic fillers with different particle sizes and surface activity, for example, MgO, Mg(OH)₂, and BaSO₄. The experimental results show that the introduction of MAA can improve the mechanical properties of SBR vulcanizates filled with MgO, Mg(OH)₂, or BaSO₄. A small amount of MAA leads to significant increases in the modulus, tensile strength, and tear strength. MMA has little effect on the mechanical properties of the SBR vulcanizates. The SEM micrographs show that MAA can improve the interfacial bonding between SBR and the three kinds of fillers. The SBR–filler interaction was studied by Kraus plots. The relationship between the SBR–filler interaction and the mechanical properties was explored. m, a characteristic constant of a filler–SBR matrix, represents the interfacial bonding between fillers and SBR and the accumulated structure of the fillers. At a given ?, a high value of m means a strong interaction between SBR and the filler and, therefore, strong mechanical properties. The Payne effect of the SBR vulcanizates was observed, and the vulcanizates have low storage moduli at high strains and high storage moduli at low strains, and the moduli are nonlinear and increase the nonlinearity as the filler content increases. The loss moduli and loss factor reach their maximums at moderate and high strain amplitudes, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 775–782, 2003     

Effect of nAl(OH)3 on thermal, mechanical and morphological properties of millable polyurethane (MPU) rubber

Aluminium hydroxide nanoparticles [nAl(OH)₃] were synthesized using continuous ultrasonic cavitation technique. The size and shape of synthesized nanoparticles were confirmed using X-ray diffraction and transmission electron microscopy, which was found to be ~55 nm in diameter with needle shape. Millable polyurethane (MPU) rubber nanocomposites were prepared with nAl(OH)₃ as a filler (0.5–2.5 wt% loading) using two-roll mill and moulded on compression moulding machine. Dicumyl peroxide was used as a curing agent. Mechanical property and abrasion resistance was determined using universal testing machine (UTM) and abrasion resistance tester, respectively. Physical (hardness and swelling index) and thermal (flammability and stability) properties were also studied on shore A hardness tester, flammability tester and thermo gravimetric analyzer, respectively. The extent of dispersion of nAl(OH)₃ in MPU matrix was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). MPU rubber:nAl(OH)₃ nanocomposites show improved mechanical, physical and thermal properties compared to pristine MPU composite. This dramatic improvement in properties was due to very small grain size of nAl(OH)₃, which facilitates uniform dispersion of nanoparticles within the chains of MPU rubber. This improvement in properties were up to 2 wt% and decreases subsequently (2.5 wt%) due to agglomeration. nAl(OH)₃ behaves like an ordinary filler at higher wt% loading.     

Barium sulfate–filled blends of polypropylene and polystyrene: Microstructure control and dynamic mechanical properties

The microstructure of filled blends consisting of a semicrystalline polypropylene homopolymer (PP) matrix and a polystyrene (PS) dispersed phase with barium sulfate (BaSO₄) filler can be controlled by an addition of maleic anhydride-grafted polypropylene (PP-g-MAH) or styrene-maleic anhydride copolymer (SMA). Scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA) in the solid and melt states were the analytical tools used. The filler is occluded at the interface of the polymer phases in the filled blend without PP-g-MAH or SMA. The addition of BaSO₄ to the PP/PS blend results in a decrease in domain size of the minor polymer phase. The filler is occluded in the PP phase when PP-g-MAH is added, while SMA results in the occlusion of the barium sulfate filler in the PS phase. The results of the SEM and the DMA studies were correlated, with indications of a filler network structure with both the PP-g-MAH and SMA modifiers. The barium sulfate filler surface has a specific affinity to maleic anhydride copolymers. The BaSO₄ filler alone did not have a nucleation effect on the PP; however, in combination with PP-g-MAH, a clear nucleation effect was observed.     

Preparation,characterization, and properties of modified barium sulfate nanoparticles/polyethylene nanocomposites as T‐shaped copper intrauterine devices

To improve the mechanical properties and shelf‐life of barium sulfate nanoparticles (BaSO₄‐NPs)/polyethylene (PE) composites, which are used as the scaffold of T‐shaped copper intrauterine devices (Cu‐IUDs) in the clinic, an Al coupling agent was used to modify BaSO₄‐NPs. The influence of the Al coupling agent on the microstructures, properties, and shelf‐life of the nanocomposites were investigated. The results showed that: (1) a chemical reaction occurred between the Al coupling agent and the hydroxyl groups adsorbed by BaSO₄‐NPs. (2) BaSO₄‐NPs modified by the Al coupling agent dispersed in the PE matrix were much better than unmodified NPs. The interface bonding between modified NPs and the PE matrix was better than unmodified NPs. (3) the maximum tensile strength of nanocomposites containing modified NPs was 11.87 MPa, flexural strength was 6.61 MPa, and the elongation rate was 66.78%. (4) After an accelerated aging experiment, the tensile strength of the nanocomposites only decreased 5–15%. All of these results indicate that m‐BaSO₄‐NPs/PE nanocomposites are more clinically useful than unmodified nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40393.     

Crystallization,mechanical, and fracture behavior of mullite fiber‐reinforced polypropylene nanocomposites

This study describes the reinforcement effect of surface modified mullite fibers on the crystallization, thermal stability, and mechanical properties of polypropylene (PP). The nanocomposites were developed using polypropylene‐grafted‐maleic anhydride (PP‐g‐MA) as compatibilizer with different weight ratios (0.5, 1.0, 1.5, 2.5, 5.0, and 10.0 wt %) of amine functionalized mullite fibers (AMUF) via solution blending method. Chemical grafting of AMUF with PP‐g‐MA resulted in enhanced filler dispersion in the polymer as well as effective filler‐polymer interactions. The dispersion of nanofiller in the polymer matrix was identified using scanning electron microscopy (SEM) elemental mapping and transmission electron microscopy (TEM) analysis. AMUF increased the Young's modulus of PP in the nanocomposites up to a 5 wt % filler content, however, at 10 wt % loading, a decrease in the modulus resulted due to agglomeration of AMUF. The impact strength of PP increased simultaneously with the modulus as a function of AMUF content (up to 5 wt %). The mechanical properties of PP‐AMUF nanocomposites exhibited improved thermal performance as compared to pure PP matrix, thus, confirming the overall potential of the generated composites for a variety of structural applications. The mechanical properties of 5 wt % of AMUF filled PP nanocomposite were also compared with PP nanocomposites generated with unmodified MUF and the results confirmed superior mechanical properties on incorporation of modified filler. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43725.     

An investigation on the mechanical and dynamic rheological properties of single and hybrid filler/polypropylene composites based on talc and calcium carbonate

Some results of experiments on the mechanical and rheological properties of mineral filled polypropylene were presented. Single filler and hybrid filler composites of talc and calcium carbonate (CaCO₃) were prepared in a co‐rotating twin‐screw extruder. The effect of filler type, filler content, and coupling agent on the mechanical and rheological properties of the polypropylene were studied. The coupling agent was maleic anhydride‐grafted polypropylene (PP‐g‐MA). It was found that the mechanical properties are affected by filler type, filler concentration, and the interaction between filler and matrix. The tensile strength of the composite is more affected by the talc while the impact strength is influenced mostly by CaCO₃ content. The elongation at break of PP/CaCO₃ composites was higher than that of PP/talc composites. The incorporation of coupling agent into PP/mineral filler composites increased the mechanical properties. Rheological properties indicated that the complex viscosity and storage modulus of talc filled samples were higher than those of calcium carbonate filled samples while the tan δ was lower. The rheological properties of hybrid‐filler filled sample were more affected by the talc than calcium carbonate. The PP‐g‐MA increased the complex viscosity and storage modulus of both single and hybrid composites. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Mechanical properties of Mg(OH)2/polypropylene composites modified by functionalized polypropylene

Modified Mg(OH)₂/polypropylene (PP) composites were prepared by the addition of functionalized polypropylene (FPP); and acrylic acid (AA) and by the formation of in situ FPP. The effects of the addition of FPP and AA and the formation of in situ FPP on the mechanical properties of Mg(OH)₂/PP composites were investigated. Experimental results indicated that the addition of Mg(OH)₂ markedly reduced the mechanical properties of PP. The extent of reduction in notch impact strength of PP was higher than that in flexural strength and tensile strength. However, tensile modulus and flexural modulus increased with increased Mg(OH)₂ content. The addition of FPP facilitated the improvement in the flexural strength and tensile strength of Mg(OH)₂/PP composites. The higher the Mg(OH)₂ content was, the more significant the effect of FPP was. The incorporation of AA resulted in further increased mechanical properties, in particular the flexural strength, tensile strength, and notch impact strength of Mg(OH)₂/PP composites containing high levels of Mg(OH)₂. It not only improved mechanical properties but also increased the flame retardance of Mg(OH)₂/PP composites. Although the mechanical properties of composites modified by the formation of in situ FPP were lower than those of composites modified by only the addition of AA in the absence of diamylperoxide, the mechanical properties did not decline with increased Mg(OH)₂ content. Moreover, the mechanical properties increased with increasing AA content. The addition of an oxidation resistant did not influence the mechanical properties of the modified Mg(OH)₂/PP composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2139–2147, 2003     

Mechanical and thermal properties of talc and calcium carbonate filled polypropylene hybrid composites

The main aim of this work was to study and compare the mechanical and thermal properties of hybrid polypropylene (PP) composites and single‐filler PP composites. With two main types of mineral fillers—calcium carbonate (CaCO₃) and talc—PP composites of different filler weight ratios (talc/CaCO₃) were compounded with a twin‐screw extruder and then injection‐molded into dumbbell specimens with an injection‐molding machine. Tensile, flexural, and impact tests were performed to determine and compare the mechanical properties of the hybrid and single‐filler PP composites. A synergistic hybridization effect was successfully achieved; the flexural strength and impact strength were highest among the hybrids when the PP/talc/CaCO₃ weight ratio was 70:15:15. The nucleating ability of the fillers and its effects on the mechanical properties were also studied with differential scanning calorimetry. Because of the influence of talc as the main nucleating agent, the hybrid fillers showed significant improvements in terms of the nucleating ability, and this contributed to the increase in or retention of the mechanical properties of the hybrid composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3327–3336, 2004     

Melt density and volume flow rate of polypropylene/Al(OH)3/Mg(OH)2 flame retardant composites

Polypropylene (PP) flame retardant composites filled with aluminum hydroxide (Al(OH)₃), magnesium hydroxide (Mg(OH)₂) as well as zinc borate (ZB) were prepared with a twin‐screw extruder. The melt volume flow rate (MVR) and density of the composites were measured by means of a melt flow rate instrument under experimental conditions with temperature of 180°C and load varying from 2.16 to 5 kg, to identify the effects of the particle size and content. The results showed that MVR of the composites decreased with an increase of the filler weigh fraction (?_f) when ?_f was more than 10 phr. The MVR decreased first and then increased with an increase of the filler diameter (d). The melt density (ρ_m) of the composites increased linearly with an increase of ?_f and decreased linearly with the increase of d. In addition, the ρ_m increased with an increase of load. Under the same experimental conditions, the MVR decreased slightly while the ρ_m increased somewhat with addition of ZB for the PP/Al(OH)₃/Mg(OH)₂ composite systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The effect of surface modification of aluminium hydroxide on the crystallisation behaviour of aluminium hydroxide filled polypropylenes

Composites based on polypropylene (PP) (homopolymer and impact modified copolymer) and surface modified aluminium hydroxide (Al(OH)₃) have been studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Filler surface modifiers used included 2-dodecen-1-yl succinic anhydride (DDSA) as a dispersant and a commercial silane based coupling agent system (BA Chemicals S21). Treatment of the Al(OH)₃ with DDSA led to a considerable reduction of the capacity of the filler to nucleate crystallisation in the PP and, in some composites, promoted growth of β-PP. With the S21 treatment, however, a nucleation effect was still apparent, despite encapsulation of the filler particles with the elastomeric phase in the case of the impact modified PP. DSC and XRD studies indicated that with the untreated filler nucleation was directly associated with the filler surface. However, with the S21 treated filler this was not the case and PP nucleation was random and/or flow induced with no association with the filler surface.     

Microstructure and fracture behavior of polypropylene/barium sulfate composites

The microstructure, mechanical properties, and fracture behavior of polypropylene (PP)/barium sulfate (BaSO₄) composites were studied. Four composite samples with different PP‐BaSO₄ interface were prepared by treating the filler with different modifiers. The fracture behavior of the composites under different strain rates was studied by means of Charpy impact tests and essential work of fracture (EWF) tests. It is shown that a moderate interfacial adhesion is favorable for toughening, which ensures that the particles transfer the stress and stabilizes the cracks at the primary stage of the deformation, and satisfies the stress conditions of plastic deformation for matrix ligaments subsequently via debonding. Very strong interfacial adhesion is not favorable for toughness, especially under high strain rate, because the debonding‐cavitation process may be delayed and the plastic deformation of matrix may be restrained. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1207–1213, 2006