Partial replacement of EPR by GTR in highly flowable PP/EPR blends: Effects on morphology and mechanical properties (original) (raw)
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Effect of addition of polyethylene on properties of polypropylene/ethylene-propylene rubber blends
Journal of Applied Polymer Science, 1996
Toughening of polypropylene was carried out by adding two types of ethylene-propylene rubber (EPR) having different ethylene content, and three commercial types of EPR containing high density polyethylene (PE). The concentration of EPR was varied from 0-30%. Globular morphology of the dispersed phase was observed at all concentrations. Average particle size of the dispersed phase (EPR) was about 2-4 pm with about 10% within the 0.5-1 pm range. Although most of the properties were not affected by the presence of polyethylene, high notched Izod impact strength was achieved only with samples containing PE. Melt flow rate, yield strength and modulus were found to decrease almost linearly with increasing elastomer concentration in the blend. Elongation a t break was enhanced by the addition of EPR, particularly those containing PE. The contribution of P E to the properties was explained by the specific EPR/PE particle morphology (core-shell or interpenetrating)
Rheological properties of ground tyre rubber based thermoplastic elastomeric blends
Polymer Testing, 2015
This work analyses the rheological behaviour of thermoplastic elastomeric blends (TPE) based on ground tyre rubber (GTR), more specifically the rheological behaviour of binary and ternary polypropylene (PP) based blends with different rubber materials: an ethylene propylene diene monomer (EPDM), an ethylene propylene rubber (EPR) and GTR. The study was developed under steady-shear rate conditions by capillary rheometry at three different temperatures. TimeeTemperature Superposition Principle (TTSP) was applied to the viscosity curves using a temperature dependent shift factor, allowing the construction of master curves for the analysed blends. The Cross-WLF model was used to predict the rheological parameters, giving numerical results for viscosity similar to the experimental data. GTR increased the blends viscosity. EPR showed rheological behaviour similar to PP, and EPDM presented higher power law behaviour. Pseudoplastic behaviour was observed for all the analysed blends. Incorporation of GTR in TPE blends for injection moulding purposes was found to be a feasible strategy to upcycle this type of potentially wasted material.
The development of rubber-thermoplastic blends from ground tyre rubber and waste polypropylene
Journal of the National Science Foundation of Sri Lanka, 2009
The aim of this thesis was to develop and process viable rubber-thermoplastics blends from ground tyre rubber (GTR) and waste polypropylene (WPP). The use of WPP with waste rubber in blends is novel, although limited studies have been carried out on virgin polypropylene (PP)-waste rubber blends. The Delink pretreatment for the GTR is also a novel technique used for property enhancement. To achieve the aim, a number of GTRlWPP blends were prepared, in different blend compositions (from 0 to 100 wt% of each polymer), at different processing parameters, and with two compatibilizing systems. One system called dimaleimide contained N-N' meta-phenylene dimaleimide (HV A-2) as the compatibilizer and either di(tert-butylperoxyisopropyl) benzene (DTBPIB) or 2-2'-dithiobenzothiazole (MBTS) as an activator. The other system contained phenolic resin compatibilizer (SP 1045H resin) and stannous chloride (SnCh) activator in two forms; anhydrous and dihydrated. The compatibilizer level varied from 0 to 5 pphp, while the activator level varied from 0 to I pphp. In a separate investigation, the GTR was pretreated with Delink up to 9 phr, and GTR treated with the resultant optimum Delink level of 3 phr (DGTR) was blended with WPP to prepare DGTRlWPP blends. All these blends were processed using a Haake Rheocord PolyLab System. The processing characteristics and the mechanical properties of these blends were investigated. The effects were explained by dynamic mechanical properties, melting and crystallization behaviour, sol/gel characteristics and by blend morphology. Morphological observations of the blends showed a two phase systems, in which GTR was dispersed as domains in the continuous WPP matrix at low GTR contents. At 70 wt% GTR, the GTR dispersed phase changed to a continuous phase. The degree of crystallinity in the WPP remained unchanged up to 60 wt% GTR, but thereafter increased slightly. The processing characteristics and the mechanical properties of the GTRlWPP simple blends were found to be varied with its composition, which directly influenced the phase morphology and the degree of crystallinity. The melt flow index, hardness, tensile strength, secant modulus at 2% strain, and tear resistance decreased with GTR content, while the melt viscosity, the elongation at break and the impact failure energy increased. The blend containing 50 wt% of each polymer produced the best balance of properties.
In this work, thermoplastic elastomers were prepared based on low-density polyethylene (LDPE) and ground tire rubber (GTR). To improve the adhesion and achieve better rubber-like properties, ethylene vinyl acetate copolymer (EVA) was selected and used as a compatibilizer. The GTR and EVA content were varied between 0-45 and 0-20 wt%, respectively. Blends with different composition were produced from the raw materials on a twin screw extruder. Tensile and instrumented falling weight impact (IFWI) specimens were injection molded from the granulated blends. Injection pressure and the shrinkage of the IFWI specimens were measured. Besides the tensile and IFWI tests, the cut cross-sections were inspected with a scanning electron microscope. Based on the results, it can be stated that the application of EVA as a compatibilizer is essential for even lower weight percentage to ensure the rubber-like properties, but as the EVA content is increased, only less additional improvement can be detected.
Polymer, 1991
Morphology, thermal behaviour and mechanical and dynamic mechanical properties of isotactic polypropylene (PP) blended with different amounts of ethylene-propylene-diene (EPDM) terpolymer were investigated. Addition of 10% (w/w) EPDM to PP resulted in an increase in spherulite size. Optical micrographs showed that the rubber was distributed both in the intra-and interspherulitic regions. The heat of fusion (AHf) and percentage crystallinity (wide angle X-ray scattering) of PP/EPDM blends decreased on increasing EPDM content. Scanning electron micrographs revealed a skin-core morphology in injection-moulded specimens. Melt viscosity of the PP/EPDM blends determined at 200°C using a capillary rheometer showed an increase with increasing rubber content. A non-Newtonian flow behaviour was observed in the shear rate range 40-1600 s-1. Dynamic mechanical analysis results also supported the incompatibility of PP/EPDM blends. An improvement in impact strength of PP was observed upon incorporation of EPDM elastomer.
International Journal of Plastics Technology, 2010
An attempt has been made to study the mechanical, viscoelastic and morphological behavior of various dynamically cross-linked blends of isotactic polypropylene (iPP) with ethylene-propylene diene rubber (EPDM) and nitrile rubber (NBR) were examined and compared with these of uncross-linked blends of iPP/EPDM/NBR. These blends were prepared by melt blending in an internal mixer at 190°C in the composition range of 10-40 wt. % EPDM/NBR elastomeric content. The variation in the strength of fibrils of the craze, yield stress and the number density of the EPDM/NBR elastomeric domains (morphology) which are important factors for enhancing the interfacial adhesion and toughness in dynamically crosslinked blends were determined. The toughness and ductility of these blends were discussed with main emphasis on the composition between crack formation and the degree of plastic deformation through crazing and shear yielding. The physicomechanical properties such as hardness, impact strength, flexural strength and flexural modulus of dynamically cross-linked blends were found to be consistent and displayed enhanced mechanical properties values as compared with uncross-linked blends. The decreases in crystallinity and nucleation effect in cross-linked blends of iPP/EPDM/NBR were considered to contribute in the improvement in the impact strength behavior of the blends prepared.
Macromolecular …, 2007
Reactive compatibilization of recycled low-or high-density polyethylenes (LDPE and HDPE, respectively) and ground tire rubber (GTR) via chemical interactions of pre-functionalized components in their blend interface has been carried out. Polyethylene component was functionalized with maleic anhydride (MAH) as well as the rubber component was modified via functionalization with MAH or acrylamide (AAm) using chemically or irradiation (g-rays) induced grafting techniques. The grafting degree and molecular mass distribution of the functionalized polymers have been measured via FTIR and Size Exclusion Chromatography (SEC) analyses, respectively. Thermoplastic elastomer (TPE) materials based on synthesized reactive polyethylenes and GTR as well as ethylene-propylene-diene rubber, EPDM were prepared by dynamic vulcanization of the rubber phase inside thermoplastic (polyethylene) matrix and their phase structure, and main properties have been studied using DSC and mechanical testing. As a final result, the high performance TPE with improved mechanical properties have been developed.
Polypropylene Blends with m-EPR Copolymers: Mechanical and Rheological Properties
Acta Chimica Slovenica, 2018
The effects of two metallocene ethylene-propylene-based elastomers (m-EPR1 and m-EPR2) differing in molecular mass and viscosity on mechanical, rheological and interfacial properties were compared. The m-EPR elastomers were added to iPP in 2.5, 5, 10, 15, and 20 vol.%. Torque values, elongation at break and impact strength measured of the iPP/m-EPR1 blends were higher than the iPP/m-EPR2 blends due to higher molten viscosity of m-EPR1 than m-EPR2 copolymer. Slight differences in Young moduli as well as in tensile strength at yield and at break might indicate that tensile properties of iPP/m-EPR blends were not significantly affected by difference in viscosity or molecular mass, miscibility and spherulite size. Optimization diagrams indicated the metallocene m-EPR copolymers are efficient impact modifiers for polypropylene and showed good balancing of mechanical properties in iPP/m-EPR blends.