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PP Composites (pp + composite)

Distribution by Scientific Domains

Polymers and Materials Science	91%

Selected Abstracts

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

JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2009
A.K. Nurdina
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 [source]

Development and characterization of an all-olefin thermoplastic sandwich composite system

POLYMER COMPOSITES, Issue 4 2002
Ganesan Kumar
In this investigation an all-olefin thermoplastic sandwich system was developed and characterized. Commingled glass fiber polypropylene (PP) composite was used as skin and HDPE (PE) foam with closed cells as core. Infra-red heating was used for melting the surfaces of the substrates for surface fusion bonding with a cold press. Two tie layer films, viz. ethylene-propylene copolymer (EPC) and HDPE/elastomer blend, were used as hot melt adhesives for bonding the substrates. Single lap shear joints were prepared from PP composite and PE foam adherends with a bonding area of 25.4 mm × 25.4 mm to determine the interface strength. EPC tie layer provided higher bond strength (27.4 kg/cm2) to the all-olefin sandwich system than HDPE/elastomer blend based one (19.7 kg/cm2). For EPC tie layer based sandwiches, a mixed mode a failure was observed in the failed lap shear samples; about 40% is cohesive failure through tie layer, and the rest of failure was adhesive either at PP composite or PE surfaces. Environmental scanning electron micrographs (ESEM) reveal that in the process of surface fusion bonding, PE foam cells in the vicinity of 0.80 mm interphase area were coalesced with high temperature and pressure. No macro level penetration of tie layer melt front into foam cells was observed. As the surface morphology of foam was altered on account of IR surface heating and the PP composite bonding side had a resin-rich layer, the bonding situation was closer to that between two polymer film surface. [source]

Flame retardation and thermal degradation of flame-retarded polypropylene composites containing melamine phosphate and pentaerythritol phosphate

FIRE AND MATERIALS, Issue 5 2008
Shun Zhou
Abstract The flame retardation of polypropylene (PP) composites containing melamine phosphate (MP) and pentaerythritol phosphate (PEPA) was characterized by limiting oxygen index (LOI) and UL 94. The morphology of the char obtained from the combustion of the composites was studied by scanning electron microscopy (SEM). The thermal degradation of the composites was investigated using thermogravimetric (TG) analysis and real-time Fourier transform infrared (RTFTIR) spectroscopy. It has been found that the PP composites containing only MP do not show good flame retardancy even at 40% additive level. Compared with the PP/MP binary composites, all the LOI values of the PP/MP/PEPA ternary composites at the same additive loading increase, and UL 94 ratings of the ternary composites at suitable MP/PEPA ratios are raised to V-0 from no rating (PP/MP). The TG and RTFTIR studies indicate that the interaction occurs among MP, PEPA and PP. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Crystalline morphology and dynamical crystallization of antibacterial ,-polypropylene composite

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008
Xin Chen
Abstract The crystalline morphology and dynamical crystallization of antibacterial polypropylene composite and pure polypropylene were investigated via differential scanning calorimeter (DSC), wide angle X-ray diffraction (WAXD), and real-time hot-stage optical microscopy (OM). The results reveal that the crystalline morphology of antibacterial PP composites changes with variations of the crystallization conditions and compositions. The crystalline phase consists of both ,-PP and ,-PP crystals. The content of ,-PP decreases with the increase in antibacterial agent content and cooling rate. With the addition of ,-nucleating agent, the morphologies of all dynamically crystallized antibacterial PP composites show no obvious spherulitic morphology, and the decrease of crystal perfection and the increase of nucleation density of antibacterial PP composite system could be observed. With the increase of antibacterial agent content, the overall crystallization rates of the antibacterial PP composite increase dramatically, while the content of ,-PP in all antibacterial PP composite decrease distinctly under given cooling conditions. These results can be explained by the interruptive effect of antibacterial agent on interactions of ,-nucleating agent components and the obstructing effect of antibacterial agent on the mobility of PP chains in melts. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Polypropylene/clay nanocomposites prepared by in situ grafting-melt intercalation with a novel cointercalating monomer

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
Pingan Song
Abstract Polypropylene (PP)/clay nanocomposites were prepared by melt-compounding PP with organomontmorillonite (OMT), using maleic anhydride grafted polypropylene (PP- g -MA) as the primary compatibilizer and N -imidazol- O -(bicyclo pentaerythritol phosphate)- O -(ethyl methacrylate) phosphate (PEBI) as the cointercalating monomer. X-ray diffraction patterns indicated that the larger interlayer spacing of OMT in PP was obtained due to the cointercalation monomer having a large steric volume and the d -spacing further increased with the addition of PP- g -MA, as evidenced by transmission electron microscopy. Thermogravimetric analysis revealed that the PEBI-containing PP nanocomposites exhibited better thermal stability than PEBI-free PP composites. Dynamic mechanical analysis demonstrated that the storage modulus was significantly enhanced, and the glass transition temperature (Tg) shifted slightly to low temperature with the incorporation of clay for PP/OMT hybrids. PEBI-containing PP/OMT composites gave a lower Tg value because of the strong internal plasticization effect of PEBI in the system. Cone calorimetry showed that the flame-retardancy properties of PP nanocomposites were highly improved with the incorporation of PEBI. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Mechanical, flow, and morphological properties of talc- and kaolin-filled polypropylene hybrid composites

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007
M. B. Abu Bakar
Abstract Polypropylene (PP) hybrid composites have been produced by compounding two types of mineral fillers, viz., talc and kaolin with PP copolymer using a twin screw extruder. The PP hybrid composite was injection-molded into dumbbell specimen for tensile, flexural, and impact properties characterizations. MFI and SEM studies were used to characterize the flow and morphological properties of the PP hybrid composites. The result shows that most of the hybrid composites showed a significant decrease in flow, tensile, flexural, and impact properties compared with the single filler-filled PP composites. However, a hybridization effect was seen for the PPT20K10 hybrid composites, through the synergistic coalescence of positive characteristics from 20 wt % of talc and 10 wt % of kaolin. This hybrid formulation have given an economically advantageous material with the mechanical properties (tensile, flexural, and impact) comparable to those of the talc-filled PP composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 434,441, 2007 [source]

Thermal oxidative degradation kinetics of PP and PP/mg (OH)2 flame-retardant composites

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007
Xiaolang Chen
Abstract The thermal stability and thermal oxidative degradation kinetics of polypropylene (PP) and flame-retardant PP composites filled with untreated and treated magnesium hydroxide (MH) in air were studied by thermogravimetric analysis (TGA). The effect of the heating rate in dynamic measurements (5°C,30°C/min) on kinetic parameters such as activation energy was also investigated. The Kissinger and Flynn,Wall,Ozawa methods were used to determine the apparent activation energy for the degradation of neat PP and flame-retardant PP composites. The results of TGA showed that the addition of untreated or treated MH improved the thermal oxidative stability of PP in air. The kinetic results showed that the apparent activation energy for degradation of flame-retardant PP composites was much higher than that of neat PP, suggesting that the flame retardant used in this work had a great effect on the mechanisms of pyrolysis and combustion of PP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1978,1984, 2007 [source]

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

Influence of Processing Temperature on Microcellular Injection-Moulded Wood,Polypropylene Composites

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006
Andrzej K. Bledzki
Abstract Summary: Microcellular wood fibre reinforced polymer materials are significant because of their possibility to reduce the density of automotive components through microcellular structure, process and product part advantages, and as a new development with bio-fibre strengthened plastics. Soft wood fibre reinforced PP composites in box part and panel shape were prepared by an injection moulding process. Polymeric microspheres as a chemical foaming agent (endothermic) were used to produce the microcellular composites. The influence of injection moulding processing temperature on the microcellular structure and properties (tensile and flexural properties, notched charpy impact strength) was investigated by varying the temperature over the 150,170,°C, 160,180,°C and 170,190,°C. A comparative study of cell morphology, weight reduction and mechanical properties was conducted between box part and panel. Microcell morphology, cell size, shape and distribution were investigated using scanning electron micrographs. The results indicated that the lower processing temperature should be below the range of 170,190,°C and processing temperature at 160,180,°C, where the composites showed finer cellular structure compared to other processing temperatures. The mechanical properties did not differ with the variation of processing temperature regardless of composite types (box part or panel). Cellular structure changes in the box part were found considering near or far from injecting point. Microcellular injection-moulded box part (geometry: 150,×,100,×,70 mm3 in size) of soft wood fibre,PP composites. [source]

Functionalization of nanoclays with ionic liquids for polypropylene composites,

POLYMER COMPOSITES, Issue 5 2009
Jin Uk Ha
Cationic nanoclays were treated by ion exchange with various ionic liquids (ILs) containing cations and anions of different structure and/or molecular weight in order to investigate the effects of the IL structure and cation chain length on extent of clay dispersion, intercalation, and thermal stability. The modified clays containing imidazolium-, pyridinium-, and phosphonium-based cations were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. Although the thermal stability of pure ILs was mostly controlled by the type of the anion present, high temperature thermal stability of the modified clays, at the IL cation loadings achieved in this work, was not significantly dependent on type, structure, or size of the cation. The latter parameters, however, were of significant importance in controlling degree of dispersion of the nanoclays during melt compounding with polypropylene (PP). Basal spacing increased proportionally to the size and type of the intercalated cations and showed little change in the PP composites. Although commercial organoclays were shown to be less thermally stable than IL modified clays, they exhibited larger basal spacing and better dispersion characteristics in the polyolefin matrix; however, they increased to the same extent the thermal stability of the PP matrix as the phosphonium modified clays. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

Mechanical properties and morphologies of polypropylene/single-filler or hybrid-filler calcium carbonate composites

POLYMER ENGINEERING & SCIENCE, Issue 2 2007
Kun Yang
Three types of polypropylene (PP) with different intrinsic toughness were used to study the mechanical properties and morphologies of the PP composites filled with single-filler and hybrid-filler of calcium carbonate particles. The calcium carbonate particles used were with average particle sizes of 25 ,m (CC25), and 0.07 ,m (CC0.07), respectively. A hybrid-filler CaCO3 named CC25/CC0.07 was used as a mixture of CC25 and CC0.07 (CC25/CC0.07 weight ratio = 1:1). It was found that the type of PP and the particle size of inorganic filler were the two important factors for the determination of mechanical properties of the composites. And the general mechanical properties of the composites filled with hybrid-filler CaCO3 were better than those of the composites filled with single-filler CaCO3, but the synergistic hybridization effect of the hybrid-filler CaCO3 did not exist. The major toughening mechanism of the PP/CC25 composites was the cavitation of the matrix caused by CC25, and the major toughening mechanism of the PP/CC0.07 composites was the pinning effect introduced by CC0.07. For the PP/CC25/CC0.07 composites, the cavitation of the matrix caused by CC25 and the pinning effect introduced by CC0.07 existed simultaneously. And when the intrinsic toughness of the matrix was large enough, the major factor to toughen PP was the pinning effect introduced by CC0.07, otherwise the major factor to toughen PP was the cavitation of the matrix caused by CC25. POLYM. ENG. SCI., 47:95,102, 2007. © 2007 Society of Plastics Engineers [source]

Flame retardancy study on magnesium hydroxide associated with clays of different morphology in polypropylene matrix

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2008
B. B. Marosfoi
Abstract Fire retardancy behavior of polypropylene,magnesium hydroxide,clay composites of different morphologies is presented. Layer- and needle-like clay nanoparticles in natural and organically surface modified form have been compared. Fire retardant performance of the composites was evaluated by conical combustor and by horizontal burning test, while the structure was characterized by SEM. Rheological analysis of varied temperature provided further information about the strength of the formed combustion residue. The results confirm that fibrous and layered clay nanofillers act synergistically and can be combined with MH microfillers advantageously for improving the flame retardancy of PP composites. Significant improvements were observed in combustion parameters, as well as in flammability classifications. Combination of montmorillonite and sepiolite type of clays resulted in the increased time to ignition, and markedly decreased heat release rate. These advancements are ascribed to the char stabilizer effect of nanofillers leading to increased strength of the residue. It is also concluded that not only the interaction between micro- and nanofillers, but also the nanofillers,nanofillers interaction plays a key role in fire retardant mechanism. Copyright © 2008 John Wiley & Sons, Ltd. [source]