Properties Of PP Composites Research Articles

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

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

실란으로 처리된 대나무 섬유(BF)를 함유한 폴리프로필렌(PP) 복합체의 물성에 대한 열처리의 영향

실란으로 처리된 대나무 섬유(BF)를 함유한 폴리프로필렌(PP) 복합체의 물성에 대한 열처리의 영향

Flame retardancy through carbon nanomaterials: Carbon black, multiwall nanotubes, expanded graphite, multi-layer graphene and graphene in polypropylene

Herein we investigate the influence of carbon additives with different particle sizes and shapes on the flame retardancy and mechanical properties of isotactic polypropylene. Thermally reduced graphite oxide (TRGO) and multi-layer graphene (MLG250), consisting of few graphene layers, are compared with spherical, tubular and platelet-like carbon fillers such as carbon black (CB), multiwall nanotubes (MWNT) and expanded graphite (EG). The different morphologies control the dispersion of the carbon particles in PP and play a key role in structure–property relationships. Uniformly dispersed CB, MLG250 and TRGO shift the onset temperature of PP decomposition to temperatures around 30 °C higher, induce a flow limit in the composites' melt viscosity and change drastically their fire behaviour. The prevented dripping and significantly increased heat absorption result in decreased time to ignition and hardly any change in the reaction to a small flame. Under forced-flaming conditions reductions in the peak heat release rate of up to 74% are achieved due to the formation of a protective layer of residue during combustion. The described effects of carbon nanomaterials on the properties of PP composites are most pronounced for well-exfoliated graphenes, making them preferable to less exfoliated, micron-sized expanded graphite or conventional spherical and tubular carbon nanoparticles.

Effect of different carbon fillers on the properties of PP composites: Comparison of carbon black with multiwalled carbon nanotubes

AbstractPolypropylene (PP)/carbon composites were prepared via melt blending PP with carbon fillers, including multiwalled carbon nanotubes (MWNTs) and carbon black (CB). Field‐emission scanning electron microscopy was used to research the morphology and dispersion of fillers in the PP matrix. The electrical properties, mechanical properties, and crystallization behaviors of PP/carbon composites were also investigated. The results show that the influence of MWNTs on the properties of PP composites is different with CB, which can be ascribed to the structure and aspect ratio difference between MWNTs and CB. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4823–4830, 2006

Water and water vapor sorption studies in polypropylene–zeolite composites

AbstractWater and water vapor sorption to porous polypropylene–zeolite composites prepared by hot pressing have been studied as a function of zeolite loading. This work presents the first report on the effect of the zeolite as a filler on the water‐sorption properties of PP composites. Water swelling experiments were conducted at 25°C using pure PP and PP–zeolite films samples having different zeolite loadings (6–40 wt %). Because PP is a hydrophobic polymer, it does not sorp any water, but the composites having 10, 20, 30, and 40% zeolites have sorbed 0.63, 1.00, 1.72 and 3.74% water, respectively. The zeolite itself at the same conditions sorbed 24.5% water. As the filler loading in the composites increased, equilibrium uptake values increased also. On the other hand, water vapor sorption and kinetics has been studied using a Cahn 2000 gravimetric sorption system. Within in the range of 0.35–0.95% water vapor was adsorbed by the composites containing 10–40 wt % zeolites. Experimental effective water vapor diffusivities of the composite films was about one order of magnitude higher (10‐fold) than the experimental water diffusion coefficient in composites. The transport of water in composites was slower than that in the liquid water due to the longer diffusion pathway and adsorption on the surface of the composites. Although the liquid water may fill all the voids in the composite, water vapor is adsorbed on the surface of the zeolite only. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3069–3075, 2003

Effect of nucleation, filler anisotropy and orientation on the properties of PP composites

Polypropylene ( pp ) composites containing CaCO 3 and talc were prepared and investigated as a function of composition. The effect of nucleation was studied by thermoanalytical methods, structure and particle orientation were investigated by electron spin resonance spectroscopy, light and electron microscopies, while tensile and fracture tests were carried out to characterize mechanical properties. For both types of composite, particle anisotropy and orientation have a more pronounced effect on properties than nucleation. Orientation of the anisotropic filler particles occurs even under mild shearing conditions and its degree depends on the composition. In tension, the composition dependences of the yield stress and tensile strength are determined by the decrease of effective load-bearing cross-section and interaction. In impact, crack initiation plays an increased role, as does the reinforcing effect of the filler. In failure of particulate-filled composites the main energy-consuming process is plastic deformation of the matrix, which is modified by the presence of the filler. Dewetting increases, while interfacial interaction and formation of an interphase decrease, plastic deformation and energy consumption.

Response Surface Methodology-A Useful Tool for the Optimization of Molecular Adhesion and Mechanical Properties of PP Composites

Response surface design has been used to optimize the concentration of adhesion promoter in wood fiber-filled polypropylene composite in relation to maximiza tion of mechanical properties and thermal stability of modified composites. The method has also been used to find an empirical correlation between product composition and inter molecular bonding that has taken place due to the reactivity of itaconic anhydride modified polypropylene in the composite system studied. The adequency of the correlation is fur ther justified by FTIR and DSC results. The heat of fusion data of polypropylene in com posite which was used as a relative measure of change in degree of crystallinity in polypro pylene matrix, fairly explains the observed effects of response variables on degree of chemical bonding and mechanical properties. The controlled variables selected in design ing the experiment, however, suggests that a further study is needed in the higher concen tration range of wood fiber and modifier to optimize the cost and performance of product. Results in this study also revealed that a ridge analysis should be performed to find an unique extreme in the experimental region which will show the direction to proceed to find the optimum in further experimentation. Overall, this study demonstrated that response surface methodology could be used to find a quantitative correlation between composite composition and mechano-chemical properties.