Melt Flow Index Test Research Articles

Effect of Starch on the Mechanical and Rheological Properties of Polypropylene

Blends of starch (tapioca) and polypropylene were prepared in various wt/wt concentrations ranging from 100% polypropylene resins to 5:95, 10:90, 20:80, 30:70, 40:60, and 50:50 wt% starch to wt% polypropylene blends. Then the rheological and mechanical properties of the resulting blends were determined using Plastometer and Universal Testing Machine respectively. Tensile strength, percentage elongation, flexural modulus, Izod impact, vicat softening temperature and melt flow index tests were carried out according to American standard for testing and materials procedure. The melt flow index was found to decrease linearly with increasing starch concentrations up to 30 wt% starch to wt% plastic, beyond which no flow was observed. The presence of starch in polypropylene was found to have positive effect on some of the mechanical properties like flexural modulus and Izod impact strength, whereas a negative impact was obtained on the tensile strength and percentage elongation. It was observed that higher starch loadings above 30% reduced the mechanical properties while lower starch loadings below 30% improved some mechanical properties. In addition, higher starch loadings above 30% does not favor the melt flow index and the Izod impact strength since there was no flow due to lower vicat softening temperature. Thus, with the aid of controlled incorporation of the starch additive, several properties of the modified polypropylene specimen could be enhanced.

Recyclability of Polyethylene/Polypropylene Binary Blends and Enhancement of Their Mechanical Properties by Reinforcement with Glass Fiber

In this work, glass-fiber-reinforced and unreinforced polypropylene-polyethylene blends were obtained to examine the effects of recycling process on the mechanical and chemical properties. Tensile strength, flexural strength, izod impact strength, and melt flow index tests were applied to test specimens. After recycling process, the mechanical properties of both glass-fiber-reinforced and unreinforced polypropylene-polyethylene blends declined. Decrease of the mechanical properties of the recycled blends was supported by scanning electron microscopy morphologies revealed separation and degradation in matrix phase. It was observed that adding glass fiber in polypropylene-polyethylene led to the improvement in mechanical properties except impact strength.

The Effect of Addition EVA and LDPE-g-MAH on Irradiated LDPE Filled with Metal Hydroxides

Electron beam irradiation efffects on polymer cross-linking used for wire and cable insulations are still being researched. This study showed that upon irradiation, ethylene vinyl acetate (EVA) and maleic anhydride grafted polyethylene (LDPE-g-MAH) addition as coupling agent to the LDPE/fillers, improved processing and mechanical properties of compounds at each irradiation dosage (0–110 kGy). A gradual increase in gel content (GC) and tensile strength (TS) with a concomitant decline in elongation at break (EB), hot set (HS) and densities of compounds were observed upon irradiation of the blends. Melt flow index test (MFI) results revealed that filler addition reduced compounds flowing and in consequence, caused difficult to process. The LDPE/EVA blends TS values decreased significantly with fillers addition (ATH, MH and ZB). Consequently, this study demonstrated that filler addition to irradiated low density polyethylene (LDPE) impaired processing and mechanical properties of compounds, whereas, LDPE-g-MAH (6–12 phr) and EVA (0–100 phr) addition to the compounds (1I–8I) improved the blends flowability and mechanical properties at each irradiation dose (0–110 kGy). Moreover, among additive fillers, MH content compounds presented the strongest adhesion forces with polymeric compounds compared with analog compounds content aluminum trihydrate (ATH) or zinc borate (ZB) at each irradiation dosage.

Control of Ethylene and Propylene Polymerisation Processes

Many polymerisation processes can be accurately controlled by the regulation of chain growth through rheological measurement of average molecular weight. This article looks at the new developments in rheological analysers that can reintroduce closed-loop control into a variety of polyethylene and polypropylene manufacturing processes. Through the study of the exact flow patterns in Melt Flow Index test, computer fluid dynamics has enabled this industry standard test method to be faithfully replicated in the some of the more advanced instruments. These instruments can now be classed as analysers and serve the intended purpose of better control of the polymerisation processes. The whole of the polymer industry can benefit from this combined system of measurement and control technology. Closed-loop control of the primary polymer manufacture can ensure that the product is made to close tolerances instead of the present permitted ±10% passband. The manufacturer can benefit from improved plant efficiency by making the desired product as well as being able to guarantee a highly consistent product. The downstream processor can benefit from reduced material usage and elimination of process set-up wastage. A large variety of recyclers and the raw material manufacturers can benefit from the new technology by introducing reaction grades of polymer into the existing processes or by improving the measurement and control of those processes that are already producing reaction grades.

Development of Novel Polymer Phase Change Material for Heat Storage Application

Polymer Phase change material (PCM's) are materials used to store Energy for a broad range of Applications. Unlike conventional storage materials, PCM absorbs and release heat at a nearly constant temperature. They store 5–14 times more heat per unit volume than sensible storage materials. Increasing demand in solar engineering and spacecraft thermal control applications; require the continuous development of such materials to maximize its efficiency. One of the options is to develop energy storage devices, which are as important as developing new sources of energy. In This paper we can show that combination of low Density Polyethylene (LDPE) paraffin wax and glycerin is an alternative material that can be used as PCM's. Differential Scanning Calorimeter (DSC); Melt Flow Index test and FTIR technique were used to characterize the new developed Compound. Results obtained indicate that a reduction of more than 10°C in melting temperature (Tm) of the pure LDPE-resin was achieved.

Characterization of alkali-treated kenaf fibre-reinforced recycled polypropylene composites

In this study, composites were produced using alkali-treated kenaf fibre and recycled polypropylene to improve the interfacial bonding between them. Maleic anhydride grafted polypropylene was used at a ratio of 1:10 to the fibre as a coupling agent. Blends are mixed together by means of a twin screw extruder and test specimens for mechanical testing were prepared through injection moulding machine. Fibre density, tensile property, elemental analysis, structural and morphological changes due to treatment was observed and their effects on the properties of the formulated composites were analyzed. Characterization of the composites was done by the tensile, flexural, impact and melt flow index tests. Thermogravimetric analysis and differential scanning calorimetry analysis were carried out to evaluate the thermal properties of the composites. Experiment showed that best tensile strength (TS) was found at 40% loading of fibre and alkali treatment of fibre enhanced the TS by 57%. Activation energies were calculated through Broido’s equation. It was also found that recycled polypropylene degrades at one stage, while composites degrade at two stages. Incorporating fibres decrease the activation energies of the composites but both coupling agent and treatment of fibres in that case enhance activation energies by 11 kJ mol−1 and 29 kJ mol−1, respectively, in the second stage. Field emission scanning electron microscope of the fractured surface showed that treatment of fibre improves the interfacial bonding between fibres and matrix. Density and water uptake of the composites were also studied in this study.

Electron beam irradiation of low density polyethylene/ethylene vinyl acetate filled with metal hydroxides for wire and cable applications

The mechanical test showed that upon irradiation, the tensile strength (TS) values of the EVA/LDPE blends increased with the addition of EVA. A gradual increase in gel content (GC) and tensile strength (TS) with a concomitant decline in elongation at break (EB) and hot set (HS) were observed upon electron beam irradiation of the blends. The densities of all compounds were found to reduce with irradiation. The melt flow index test (MFI) results revealed that addition of ATH and MH reduced the flowability and addition of EVA improved the processability of the LDPE/EVA blend compounds. The TS of the LDPE/EVA blends deteriorated with the addition of flame retardants. The thermal stability and flame behavior of the halogen free flame retarded composites were studied by thermogravimetric analysis (TGA), limiting oxygen index (LOI), and cone calorimeter. The TGA results revealed that the decomposition temperatures of water evolved from the compounds incorporated with MH were significantly higher than that of ATH (i.e. 218–560 °C versus 310–610 °C). The minimum smoke density generation during the combustion obtained with 30% EVA content at both ATH and MH blends. The electrical test showed that the volume resistivity (VR) of the EVA/LDPE blends decreased with increase of EVA, ATH and MH contents, whereas, it declined with increasing irradiation dose. Consequently, this study demonstrated that addition of MH to the irradiated EVA/LDPE blends resulted higher thermal stability, better flammable retardancy, electrical and mechanical properties than addition ATH to the irradiated blends for wire and cable applications.

Preparation of modified starch‐grafted poly(lactic acid) and a study on compatibilizing efficacy of the copolymers in poly(lactic acid)/thermoplastic starch blends

AbstractThis study has concerned preparation of polylactic acid grafted with maleated thermoplastic starch (PLA‐g‐MTPS) and a study on compatibilizing efficacy of the above copolymers in PLA/thermoplastic starch (TPS) blends. The PLA‐g‐MTPS copolymers were prepared by two‐step reaction. First, maleated thermoplastic starch (MTPS) was prepared by reacting cassava starch with glycerol and maleic anhydride (MA). Second, the MTPS was grafted onto PLA molecules using peroxide as an initiator. Chemical structures of the products were characterized by using Fourier transform infrared spectroscopy and 1H‐NMR techniques, whereas the acid numbers of the copolymers were determined by titration. Thermal characteristic of the copolymer was also characterized by using dynamic mechanical thermal analysis. In total, 5 wt % of the graft copolymer was blended with PLA and TPS in a twin screw extruder. Mechanical, rheological, and morphological properties of the blends were evaluated via tensile test, melt flow index test, and scanning electron microscopy, respectively. It was found that mechanical properties of the blends depended on starch content and type of the PLA‐g‐MTPS. When the PLA‐g‐MTPS was prepared at low amount (0.25 pph) of peroxide, the mechanical properties of the blend was improved remarkably as compared to those of the normal blend and/or the blend containing different compatibilizers. Compatibilizing efficacy of the above copolymers became more obvious when the thermoplastic starch (TPS) blending ratio was increased. The above results were ascribed in the light of change in the viscosity and morphology of the blends. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Optimization of Compression Moulding Temperature for Polypropylene Materials

Abstract In this work, the effect of processing temperature of polypropylene (PP) on the viscosity and the melt flow index (MFI) is studied towards the best fabrication of PP/kenaf composites. PP with MFI grade 41 and as density value of 0.95 g/cm3 is used as a raw material. The compression moulding machine is utilized to produce the moulded samples from PP pallets. The viscosity and the MFI tests have been selected as criteria to determine an optimum processing temperature. As optimum temperature 230°C has been found.

Stability of ABS compounds subjected to repeated cycles of extrusion processing

AbstractIn this work, poly(acrylonitrile‐butadiene‐styrene) (ABS) was subjected to five subsequent extrusion cycles and the effect of prolonged exposure to heat and shear stresses on its structural and performance properties was investigated. More specifically, the resulting chemical changes were studied by attenuated total reflectance Fourier transform infrared spectroscopy, the thermal response was recorded on differential scanning calorimetry thermographs, whereas the thermal stability of reprocessed samples was detected with thermogravimetric analysis. Also, the rheological properties of the aforementioned compounds were investigated via melt flow index tests, to assess their processability during melt mixing and molding processes. Furthermore, the mechanical properties of the obtained composites were investigated and the observed interactions were interpreted in terms of the influence of each component on the functional properties of the final mixture. This attempt might be a contribution to recycling of ABS by means of techniques that include multiple reprocessing. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Preparation of poly(acrylonitrile–butadiene–styrene)/montmorillonite nanocomposites and degradation studies during extrusion reprocessing

AbstractIn this study, the preparation of organically modified montmorillonite/poly(acrylonitrile–butadiene–styrene) (ABS) nanocomposites was studied by melt blending in a twin‐screw extruder. The composite material was subjected to a series of five extrusion cycles, and the effect of reprocessing on the material's structural properties was investigated. More specifically, chemical changes were studied with attenuated total reflectance/Fourier transform infrared analysis, the thermal response was recorded by differential scanning calorimetry experiments, and the thermal stability was detected with thermogravimetric analysis. Also, the rheological properties of these blends were investigated via melt flow index tests as a measure of their processability during melt mixing and molding processes. Furthermore, the mechanical strength of the obtained mixtures was explored, and the observed interactions were interpreted in terms of the influence of each component on the functional properties of the final mixture. This attempt enriched our knowledge about the recycling of ABS, with the additional aspect of the use of collected data from more complex systems, that is, composite materials, where the montmorillonite nanoparticles play a role in the interactions initiated by repeated processing. The experimental results of this study show that the reprocessing of ABS/montmorillonite induced oxidation products, but the rheological, mechanical, and thermal properties and the thermal and color stabilities of the composites remained almost stable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009