Dispersed Phase Size Reduction Research Articles

The effect of different compatibilisers on the morphology and rheological properties of PP/PET polymer blends

ABSTRACT In the present study, the compatibilisation of polypropylene/polyethylene terephthalate (PP/PET) blends with different types of compatibilisers including maleic anhydride-grafted polypropylene (PP-g-MA), glycidyl methacrylate-grafted polypropylene (PP-g-GMA) and ethylene propylene diene monomer (EPDM) rubber in different concentrations was examined. Samples were evaluated in terms of morphology, thermal and rheological properties. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC) were used. According to the results, all samples had a matrix-droplet morphology. Moreover, with increasing the compatibiliser and its concentration, the droplet sizes in dispersed phase decreased. In other words, compatibilised PP/PET showed a greater dispersed phase size reduction, lower crystallinity percentage and larger storage modulus at low frequencies in comparison with non-compatibilised PP/PET blend. Among different samples, polymer blend compatibilised with PP-g-MA (5 phr) indicated the lowest particle size and significantly improved the compatibilisation of the PP/PET blend.

An investigation on recycled PET/PP and recycled PET/PP‐EP compatibilized blends: Rheological, morphological, and mechanical properties

ABSTRACTThe effectiveness of P(E‐co‐MA‐co‐GMA) as a compatibilizer for recycled PET/PP and recycled PET/PP‐EP (polypropylene (ethylene‐propylene) heterophase copolymer) blends was investigated by means of morphological (scanning electron microscopy), rheological (small amplitude oscillatory shear), mechanical (tensile, flexural and impact tests), and thermal (differential scanning calorimetry) properties. Compatibilizer concentration ranged from 1 to 5 wt % with respect to the whole blend. All blends were obtained in a 90/10 composition using a twin screw extruder. Compatibilization effects for PETr/PP‐EP were more pronounced due to ethylene segments present in both PP‐EP and P(E‐co‐EA‐co‐GMA). PETr/PP‐EP has shown greater dispersed phase size reduction, a more solid‐like complex viscosity behavior and larger storage modulus at low frequencies in relation to PETr/PP blend. For both investigated blends, mechanical properties indicated an improvement in both elongation at break and impact strength with increasing compatibilizer content. PETr/PP‐EP blends showed improved performance for the same level of compatibilizer content. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41892.

Temperature-dependent compatibilizing effect of graphene oxide as a compatibilizer for immiscible polymer blends

We demonstrated the compatibilizing effect of graphene oxide (GO) in the immiscible poly(methyl methacrylate)/polystyrene (PMMA/PS, 80/20) blend and showed that such a compatibilizing effect was affected by the processing temperature. For the blends prepared at a relatively low temperature (190 °C), the incorporation of 0.5 wt% of GO results in a dramatic reduction in the domain diameter of dispersed minor phase (PS), indicating that GO is an effective compatibilizer. Increasing the processing temperature decreases the dispersed phase size reduction, illustrating that the compatibilizing effect of GO is adverse to processing temperature. The characterization results including the changes in chemical composition of GO and morphologies evolution of blends at different annealing temperatures reveal that this temperature-dependent compatibilizing effect should be attributed to the in situ thermal reduction of GO during the melt processing, which breaks the hydrophilicity-hydrophobicity balance of GO and renders it more hydrophobic. A comparative experiment shows that chemically reduced GO has almost no compatibilizing effect for PMMA/PS blends, which further confirms the proposed mechanism. In addition, the GO-compatibilized blends exhibit great improvement in the mechanical properties than uncompatibilized blends.

Effects of Zinc Salts of Sulfonated Natural Rubber on Mechanical Properties, Morphology and Compatibility of Natural Rubber/Chlorosulfonated Polyethylene Blends

Abstract Rubbery ionomer based on zinc salt of sulfonated natural rubber (Zn-SNR) was employed as a new compatibilizer to prepare blends of natural rubber (NR) and chlorosulfonated polyethylene (CSM) with different compositions by melt mixing process. Epoxidized natural rubber (ENR), known as an effective compatibilizer for such blends, was also incorporated into the blends. The role of ionomer and ENR on NR/CSM blend properties and morphology was evaluated by mean of tensile measurement, oil resistance testing, DMTA and SEM. The tensile properties and oil resistance of the blends were found to increase with respect to CSM content, and increased further on compatibilization with Zn-SNR and ENR. The blends compatibilized with Zn-SNR showed a similar or higher level of improvement in tensile strength and elongation at break as compared to those of ENR. The tensile strength for all of the compatibilized blends was greater than that of corresponding neat blends by 23 to 113%. The mechanism for enhancing in tensile properties of the blends using the Zn-SNR compatibilizing agent has been proposed. The observation of DMTA and SEM showed that the blends were two-separated phase morphology. However, the addition of Zn-SNR to NR/CSM blends resulted in promoted compatibility as indicated by a shift in the tan peak of CSM to lower temperature, a reduction in dispersed phase size and better adhesion between NR and CSM. These results demonstrated that the Zn-SNR is a new reactive compatibilizer for NR and CSM blends.

The effect of zinc oxide addition on the compatibilization efficiency of maleic anhydride grafted high‐density polyethylene compatibilizer for high‐density polyethylene/polyamide 6 blends

AbstractA high‐density polyethylene with grafted maleic anhydride units has been investigated as a compatibilizer for high‐density polyethylene with polyamide 6. The material acts as an effective compatibilizer, causing a marked reduction in dispersed phase size as well as an increase in tensile strength and toughness. Compatibilizer also affects the glass‐transition temperature, crystallization kinetics, and amount of crystalline material for certain blend compositions. The addition of zinc cations, which are effective in increasing ethylene‐acid copolymer compatibilizer performance in low‐density polyethylene/polyamide blends, has little, if any, effect on compatibilizer performance in these high‐density polyethylene/polyamide blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3871–3881, 2007

Rheological Behaviour of PP/PET and Modified PP/PET Blends. II. Dynamic Viscoelastic Properties

The increasing amount of post-consumer waste leads to a search for effective recycling methods. Compatibilisation of immiscible blends of polypropylene (PP) and polyethylene terephthalate (PET) represents one such novel approach that allows recycling of significant scrap materials without any need for separation steps. The intention of this paper is to investigate the dynamic viscoelastic properties of unmodified and modified PP/PET blends. To study the effect of the matrix, three polypropylenes differing in flow properties were chosen. The compatibilisation was carried out by both one- or two-step reactive in situ techniques. In the former case, the addition of 1 wt.% of maleic anhydride, and in the latter, polypropylene supplied already modified by the producer were employed. The measurements were performed by using a rotational cone and plate rheometer at temperatures of 265 °C and 245 °C. Since PET is not melted at the lower temperature, completely different behaviour is observed in the two cases. The rheological functions generally decrease with PET content at 265 °C (conventional blend behaviour), while they increase at 245 °C, in a manner reminiscent particle-filled systems (including the yield behaviour). The positive effect of compatibilisation can be deduced not only from the results of the morphological study (dispersed phase size reduction, strengthened interfacial adhesion), but also through increased values of the viscous and elastic characteristics, which suggests enhanced interactions between the blend components. Comparing steady shear and dynamic viscoelastic properties, the extent of deformation applied during both types of measurements leading to different material responses should be considered.

Morphology Effects from Advances in Polymer Blend Processing

Abstract Innovations in the processing of polymers and polymer mixtures can have unintended consequences for microstructure. Microscopic investigations have been motivated in some cases by acquisition of new processing machinery which is larger, such as the supercompounding extruders. Strategies to expand the capacity of existing machines also necessitate detailed property and morphology comparisons between old and new batches of commercially important blends. Other types of innovations use a temporary processing aid. Dispersed phase size reduction in melt blends on addition of supercritical carbon dioxide has been reported for PMMA/PS blends. TEM images showed smaller, more uniform domains attributed to reduction in melt viscosity. Blends are also under investigation now in flash spun plexifilament fibers to extend the range of end-use properties, but the need for a common solvent limits the possible pairs of polymers. A two-step R.UO4 vapor staining procedure, in which the bulk and sectioned material are exposed, has been used to examine non-equilibrium morphologies frozen in from flash spinning.

The relative role of coalescence and interfacial tension in controlling dispersed phase size reduction during the compatibilization of polyethylene terephthalate/polypropylene blends

The breaking thread and the sessile drop methods have been used to evaluate the interfacial tension between a polypropylene (PP) and a polyethylene-terephthalate (PET). An excellent correlation was found between the two. The breaking thread technique was then used to evaluate the interfacial tension of these blends at various levels of a styrene-ethylene butylene-styrene grafted with maleic anhydride (SEBS-g-MA) compatibilizer. In order to evaluate the relative roles of coalescence and interfacial tension in controlling dispersed phase size reduction during compatibilization, the morphology of PP/PET 1/99 and 10/90 blends compatibilized by a SEBS-g-MA were studied and compared. The samples were prepared in a Brabender mixer. For the 10/90 blend, the addition of the compatibilizer leads to a typical emulsification curve, and a decrease in dispersed phase size of 3.4 times is observed. For the 1/99 blend, a 1.7 times reduction in particle size is observed. In the latter case, this decrease can only be attributed to the decrease of the interfacial tension. It is evident from these results that the drop in particle size for the 10/90 PP/PET blend after compatibilization is almost equally due to diminished coalescence and interfacial tension reduction. These results were corroborated with the interfacial tension data in the presence of the copolymer. A direct relationship between the drop in dispersed phase size for the 1/99 PP/PET blend and the interfacial tension reduction was found for this predominantly shear mixing device. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2271–2280, 1997

The relative role of coalescence and interfacial tension in controlling dispersed phase size reduction during the compatibilization of polyethylene terephthalate/polypropylene blends

The breaking thread and the sessile drop methods have been used to evaluate the interfacial tension between a polypropylene ( PP ) and a polyethylene-terephthalate (PET). An excellent correlation was found between the two. The breaking thread technique was then used to evaluate the interfacial tension of these blends at various levels of a styrene-ethylene butylene-styrene grafted with maleic anhydride (SEBS-g-MA) compatibilizer. In order to evaluate the relative roles of coalescence and interfacial tension in controlling dispersed phase size reduction during compatibilization, the morphology of PP/PET 1/99 and 10/90 blends compatibilized by a SEBS-g-MA were studied and compared. The samples were prepared in a Brabender mixer. For the 10/90 blend, the addition of the compatibilizer leads to a typical emulsification curve, and a decrease in dispersed phase size of 3.4 times is observed. For the 1/99 blend, a 1.7 times reduction in particle size is observed. In the latter case, this decrease can only be attributed to the decrease of the interfacial tension. It is evident from these results that the drop in particle size for the 10/90 PP/PET blend after compatibilization is almost equally due to diminished coalescence and interfacial tension reduction. These results were corroborated with the interfacial tension data in the presence of the copolymer. A direct relationship between the drop in dispersed phase size for the 1/99 PP/PET blend and the interfacial tension reduction was found for this predominantly shear mixing device.