Haake Rheocord Mixer Research Articles

Design of experiments for thermo-mechanical behavior of polypropylene/high-density polyethylene/nanokaolinite clay composites

This paper deals with the preparation of nanocomposites using polypropylene (PP)/high-density polyethylene (PE) blend and low-cost nanokaolinite clay by melt compounding in a Thermo Haake Rheocord mixer. The optimization of processing parameters and nanoclay content is done using Box–Behnken design of response surface methodology. Mechanical properties are modeled in terms of processing parameters and nanoclay content and results are verified using statistical analysis. Most reports suggest that kaolinite clay is difficult to disperse in polymer matrix compared to costly montmorillonite clay. This difficulty is overcome by surface modification of nanokaolinite clay by an organic group and the effect of modification is studied using melt flow index, thermal stability and dynamic mechanical behavior. Morphological characterization is done by scanning electron microscopy and X-ray diffraction. Study shows that cheap and abundantly occurring nanokaolinite clay is an efficient reinforcing agent for PP/PE blend. Design of experiments can be effectively used to model such a system, which is influenced by a number of variables. It is also observed that surface modification of the nanoclay with an organic group leads to remarkable improvement in the thermal and mechanical properties of the blend.

Short Nylon 6 Fibre Reinforced Polystyrene/Natural Rubber Blends: Effect of Maleated-Polystyrene Compatibiliser

Nylon 6 short fibre was used to prepare composites based on blends of 85/15 Polystyrene (PS)/Natural rubber (NR) to study the effects of surface modification of the fibres and a compatibiliser based on PS. Initially, the loading of fibre, cut to 6 mm length, was varied from 0 to 3 wt.% in a 85/15 PS/NR blend. The composites were prepared on a Thermo Haake Rheocord mixer at 170 °C and sheeted out on a two-roll mill. Tensile, flexural and impact test samples were punched out from sheets and tested to study the mechanical and dynamic mechanical properties. It was found that the tensile properties, flexural properties and impact strength increased with the fibre content up to 1 wt.%, above which there was a significant deterioration in the properties. The fibre surface was further modified by alkali treatment and a reactive compatibiliser based on maleic anhydride-grafted-polystyrene (MA-g-PS) was used in an effort to improve the performance of the composites. The treated Nylon fibre in conjunction with the compatibiliser improved the tensile properties, flexural properties and impact strength. Dynamic mechanical analysis showed that by using the modified fibre and the compatibiliser, the storage modulus of the composite could be significantly improved. The fibre-matrix morphology was studied by SEM analysis of the tensile fractured specimens. Examination of the fibre extracted from the treated fibre composites revealed that some fraction of the matrix was bonded to the fibre surface. These results suggest that a combination of hydrolysed fibre and MA-g-PS increases the interfacial adhesion between the fibre and the matrix.

Chemical Modification of Polyamide 6 by Chain Extension with Terephthaloyl-biscaprolactam

The chain extension behaviors of terephthaloyl-biscaprolactam (TBC), 2,2′-bis(2-oxazoline)(BOZ), 2,2′-(1,3-phenylene)bis(2-oxazoline)(MPBO), TBC/BOZ, and TBC/MPBO, were studied to evaluate the coupling effect on polyamide 6 (PA6) in a Haake Rheocord mixer and an extruder. For the chain extension of PA6 with TBC only, the coupling results showed that there was an optimal dosage of chain extender, shortage of which caused incomplete chain extensions and excess of which led to more blocking reactions. When the added amount of TBC chain extender in PA6 was 0.684 wt%, the intrinsic viscosity of the PA6 increased from 1.630 to 1.848 dl/g, and the concentration of the amine end groups in the chain-extended PA6 decreased from the initial 5.12 × 10−5 to 1.96 × 10−5 mol/g. However, for the chain extension of PA6 with TBC/BOZ and TBC/MPBO mixtures, the intrinsic viscosity of PA6 increased to 2.189 dl/g and 2.097 dl/g, respectively, while at the same time both the concentration of carboxyl end-groups and amine end-groups of chain-extended PA6 decreased. The effect of temperature on the time needed for the completion of the chain extension reaction was not obvious, and the time needed for the completion of the reaction was about 200 sec. The chain-extended PA6 dissociated at high temperature, and the degradation is suggested to proceed simultaneously from the onset of the chain extension reaction. Furthermore, the effects of chain extenders on the thermal properties of chain-extended PA6 were investigated. The thermal stability of chain-extended PA6 was slightly improved.

Modeling of L‐lactide Polymerization by Reactive Extrusion

AbstractThe kinetics of L‐lactide ring‐opening polymerization initiated by stannous octoate and triphenylphosphine was investigated in a batch apparatus (Haake Rheocord Mixer). Based on the experimental data, a kinetic model is developed, considering a coordination‐insertion mechanism. Reactive extrusion experiments were further conducted for the same polymerization process, on a co‐rotating twin screw extruder. The melted material flow and mixing was described by using the Ludovic® commercial simulator. Based on the developed kinetic model and simulated flow of L‐lactide polymerization mixture, a mathematical model of reactive extrusion process is formulated, describing the evolutions of monomer conversion and average molecular weight along the extruder. The model is predicting with a reasonable good accuracy the experimental data.

Microstructure and properties of PET/EPDM, EPDM-g- MA/organoclay ternary hybrid nanocomposites: effect of blending sequence

AbstractPoly(ethylene terphthalate) (PET)/organomontmorilonite (OMMT)/maleic anhydride ethylene-propylene-diene rubber (EPDM-g-MA) nanocomposites were prepared via melt blending of the ingredients in a Haake Rheocord mixer. To make the hybrid composites, four different blending routes were examined: 1) preparing EPDM/EPDM-g-MA (EPMA)/organoclay nanocomposite and then blending it with PET, (S1), 2) dispersion of organoclay in PET and then blending it with EPMA, (S2), 3) blending PET with EPMA and then mixing it with organoclay, (S3), 4) blending PET, EPMA and organoclay in a single process, (S4). The microstructure of the PET/(EPMA)/organoclay ternary hybrids were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The result showed that the blending sequence greatly affects the dispersion of organoclay in the polymer matrix as well as the microstructure of the blends. Mechanical behavior of the blends including tensile and impact properties were also studied. Results revealed that PET/ (EPMA)/organoclay nanocomposites made by mixing sequence, S1, has the maximum tensile and impact strength among the others. This was attributed to its fine “Sea-Island” morphology and good dispersion of the organoclay in the continuous PET matrix.

Chain Extension of Polyamide 6 Using Bisoxazoline Coupling Agents

The chain extension behaviors of 2,2′-(1,3-phenylene)bis(2-oxazoline) (MPBO) and 2,2′-bis(2-oxazoline) (BOZ) were studied to evaluate the coupling effect on polyamide 6 (PA6) in a Haake Rheocord mixer and an extruder. The coupling results showed that there existed an optimal dosage of chain extender, lack of which caused deficiency of chain extension and excess of which led to more blocking reaction. The effect of chain extension with MPBO was shown to be inferior to BOZ. When the optimum amount of chain extenders was added in PA6, the intrinsic viscosity of the polyamide 6 increased from 1.632dl/g to 1.787dl/g(MPBO) and 2.031dl/g(BOZ), respectively. The reaction time decreased very fast with an increase in the temperature. The chain-extended products dissociated at high temperature; the degradation is suggested to proceed from the onset of the chain extension reaction, as do the coupling and blocking reactions. Furthermore, the effects of MPBO and BOZ on the thermal and mechanical properties of chain-extended PA6 were also investigated.

Chemical modification of polyamide‐6 by chain extension with 2,2′‐bis(2‐oxazoline)

AbstractThe chain‐extension behavior of 2,2′‐bis(2‐oxazoline) (BOZ) was studied to evaluate the coupling effect on polyamide‐6 (PA6) in a Haake Rheocord mixer and an extruder. The relative torque of PA6 dramatically increased within 1–2 min, and the results were similar whether the added amount of BOZ in PA6 was the theoretical amount or twice as much at 240 °C; however, after 5 min, the coupling results showed an optimal dosage of the chain extender, a lack of which caused a deficiency of chain extension and an excess of which led to a greater blocking reaction. The final torque was 2.16 times as much as that of a control sample when the reaction temperature was 240 °C, and the added amount of BOZ in PA6 was 1.156%; at the same time, the initial carboxyl content of the chain‐extended products decreased to 40% for PA6, and this corresponded to the intrinsic viscosity of PA6 increasing to 1.636 dL/g, whereas that of the control sample was 1.384 dL/g. Furthermore, the effects of BOZ on the thermal and mechanical properties of chain‐extended PA6 were investigated. The degree of crystallinity decreased as the chain extender was added to PA6. The Izod impact strength, tensile strength, and elongation at break of the resultant products dramatically improved under wet conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1976–1982, 2007

Phase Morphology Development in Uncompatibilized and Reactively Compatibilized Nylon‐6/Ethylene Propylene Rubber (EPR) Blends: Effect of Mixer Type on Morphology

The evolution of phase morphology in uncompatibilized and reactively compatibilized nylon‐6/ethylene propylene rubber (EPR) blends has been investigated by scanning electron microscopy with special reference to the effect of mixer type and size. Three types of mixing instruments were used for the melt preparation of the blends. These include the Haake Rheocord mixer, the DSM twin‐screw mini extruder, and the industrial Werner Pfleiderer twin‐screw extruder (ZSK‐25). In the reactively compatibilized blends, EPR‐g‐maleic anhydride (MA) has been used as the compatibilizer precursor. The MA group of the EPR reacts with the amino group of nylon forming a graft copolymer at the interface, which decreases the interfacial tension and suppresses the coalescence. In the case of uncompatibilized blends the final morphology is developed within 3–4 min of the mixing time in the DSM twin‐screw mini extruder. The size of the dispersed phase in the uncompatibilized blends, as obtained in the Werner Pfleiderer twin‐screw extruder and the DSM mini extruder, was found to be smaller than that obtained in the Haake Rheocord mixer on account of elongational flow occurring in the twin‐screw extruder. In the case of the Werner Pfleiderer twin screw extruder, sampling was done at various points in order to understand the evolution of the phase morphology along the axis of the extruder. It has been found that the final morphology of the uncompatibilized blends in the Werner Pfleiderer extruder is controlled by the geometry of the die at the exit. In the case of reactively compatibilized blends, the morphology development in the DSM twin‐screw mini extruder was so fast that the final morphology developed within 30 sec of mixing. This occurs because since the compatibilizer formed as a result of the reaction remains located at the blend interface, coalescence is substantially suppressed, and thereby the blend system rapidly attains a stable morphology. Finally the size of the dispersed phase and morphology development in reactively compatibilized blends in the three mixers were carefully studied and compared.

On the compatibility of the IPP/PA6/EPDM blends with and without functionalized IPP I. Thermo-oxidative behaviour

Binary isotactic polypropylene (IPP)/polyamide 6 (PA6) and ternary IPP/PA6/ethylene–propylene diene terpolymer (EPDM) blends in various ratios were obtained in a Haake Rheocord mixer. Processing behaviour was changed in the presence of IPP functionalized with bismaleimide (BMI), maleic anhydride (MA) and acrylic acid (AA) as reactive compatibilizing agents. The thermal and thermo-oxidative behaviour of blends was studied by differential scanning calorimetry and thermogravimetry. The functionalized IPPs modify the crystallinity degree and the decomposition behaviour of both IPP and PA6 as a result of chemical reactions of functional groups with those of the PA6. The changes depend on the IPP/PA6 or IPP/PA6/EPDM ratio, the chemical nature and amount of the functionalized IPP. On the basis of the processing and thermal data one can conclude that the compatibilizing agent effect increases in the following order: IPP-AA <IPP-BMI≈IPP-MA.

Effect of blending sequence on the microstructure and properties of PBT/EVA‐g‐MAH/organoclay ternary nanocomposites

AbstractTernary nanocomposites based on poly(butylene terephthalate) (PBT), maleic anhydride grafted poly(ethylene‐co‐vinyl acetate) (EVA‐g‐MAH), and organically modified montmorllonite (organoclays) were prepared through four different blending sequences in a Haake rheocord mixer: (1) To blend PBT, EVA‐g‐MAH and organoclays in one step; (2) First to prepare EVA‐g‐MAH/organoclay nanocomposite, then mix it with PBT to get the final nanocomposite; (3) To mix PBT with organoclays first, then the PBT/organoclay nanocomposite with EVA‐g‐MAH. (4) To mix organoclays with the PBT/EVA‐g‐MAH blend. The microstructure of the PBT/EVA‐g‐MAH/organoclay ternary hybrids was characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the blending sequence significantly influences the microstructure of PBT/EVA‐g‐MAH/organoclay ternary hybrids and the dispersion behavior of the organoclays in the polymer matrix. Tensile and impact properties of the hybrids were also studied. The results showed that the mixing sequence (2) gives the best tensile and impact strength due to its fine “sea‐island” morphology of PBT/EVA‐g‐MAH blend and good dispersion of the organoclays in the continuous PBT matrix.

The use of high resolution 13C CP/MAS solid-state NMR spectroscopy in the investigation of chain mobility in PP–NBR blends

Blends of polypropylene (PP) and acrylonitrile rubber (NBR) were prepared in a Haake Rheocord Mixer model 9000, coupled with a mixer chamber (cam rotors), in a proportion of 60:40/PP:NBR. These blends were processed in the presence of either the phenolic resin SP-1045 or a derivative from cashew nut shell liquid (CNSL), in a concentration of 10%. Solid state 13C-NMR data using the cross-polarization mode, with magic-angle spinning (CP/MAS) and delayed contact time technique, was used to evaluate both the influence of the different phenolic resins and the addition technique on molecular mobility in the blends. Substantial differences have been observed concerning flexibility by changing the nature of the resin and the way it is introduced in the mixture.

Nylon 6/ethylene propylene rubber (EPM) blends: Phase morphology development during processing and comparison with literature data

The morphology of immiscible blends of nylon 6 and ethylene propylene rubber blends (EPM) was studied. The blends were prepared by melt blending in a twin-screw miniextruder and a Haake Rheocord mixer. The influence of the blend ratio, time of mixing, rotation speed of the rotors, mixing temperature, and quenching of the extruded melt at low temperature on the phase morphology of the blends was quantitatively analyzed. The morphology was examined by scanning electron microscopy (SEM) after preferential extraction of the minor phase. The SEM micrographs were quantitatively analyzed for domain-size measurements. The morphology of the blends indicated that the EPM phase was preferentially dispersed as domains in the continuous nylon matrix up to 40 wt % of its concentration. A cocontinuous morphology was observed at 50 and 60 wt % EPM content followed by a phase inversion beyond 60 wt % of EPM where the nylon phase was dispersed as domains in the continuous EPM phase. The size, shape, and distribution of the domains were evaluated by image analysis as a function of the blend composition. The effect of the time of mixing on the phase morphology was studied up to 20 min for the 30/70 EPM/nylon blend. The most significant domain breakup was observed within the first 3 min of mixing followed by a leveling off up to 15 min. This may be associated with the equilibrium between the domain breakup and coalescence. The influence of rotor speed on the morphology was insignificant at a high rotor speed although a significant effect was observed by changing the rotor speed from 9 to 20 rpm. The influence of high-temperature annealing, repeated cycles of extrusion, the molecular weight of the nylon matrix, and the nature of the mixer type (twin-screw miniextruder versus Haake Rheocord mixer) on the morphology was also investigated in detail. The experimental results were compared with literature data. Finally, the extent of interface adhesion in these blends was analyzed by examination of the fracture-surface morphology. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1405–1429, 1999

PP-EPDM-NBR blends - The influence of added phenolic resin on processing and mechanical properties

Polypropylene (PP), ethylene-propylene-diene terpolymer (EPDM) and acrylonitrile rubber (NBR) in different proportions were mixed in a Haake Rheocord Mixer. To these mixtures phenolic resin was added in various concentrations, during processing, and the effects of this addition on processing and mechanical properties of the resulting blends were investigated.

Effect of phenolic resin on processing and mechanical properties of PP-NBR blends

Polymer mixtures based on polypropylene (PP) and acrylonitrile rubber (NBR) were prepared in a Haake Rheocord Mixer model 9000, coupled with a mixer chamber (cam rotors), in a proportion of 60:40/PP:NBR. These mixtures were processed in the presence either of phenolic resin SP-1045 or a phenolic derivative synthesized with cashew nut shell liquid (CNSL) distillate, in different concentrations. The influence of this component, as well as its concentration were evaluated by some processing data and through mechanical tests.