Postconsumer polyethylene terephthalate (PET)/polyolefin blends through reactive processing (original) (raw)
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Polymer Bulletin, 2002
Blends of recycled poly(ethylene terephthalate) (R-PET) and high-density polyethylene (R-PE), obtained from post-consumer packaging materials, were prepared both by melt mixing and extrusion processes and compatibilized by addition of various copolymers containing functional reactive groups, such as maleic anhydride, acrylic acid and glycidyl methacrylate. The effect of the type and concentration of compatibilizer, as well as the mixing conditions, on the phase morphology, thermal behaviour, rheological and mechanical properties of the blends was investigated. The results indicated that addition (5÷10 pph
Reactive compatibilization of polypropylene/polyethylene terephthalate blends
Polymer Engineering & Science, 1999
The reactive compatibilization of polypropylene/polyethylene terephthalate (PP/PEJr) blends by addition of glycidyl methacrylate grafted PP (PP-g-GMA) was studied. Two PP-g-GMA copolymers, containing either 0.2 or 1.2 w-t ?! of GMA, were used as interface modifiers. These were incorporated into PP blends (with either 70 or 90 wto/o PET), replacing 1/5 of PP in the system. The use of these modifiers changed the blends' tensile mechanical behavior from fragile to ductile. Blend tensile strength was improved by 10?? and elongation at break showed 10 to 20-fold increases while stif€ness remained constant. Scanrun. g electron micrographs showed the PP average domain size in injection molded specimens to decrease to the micron/sub-micron size upon addition of the GMA modified resins, while the unmodified blends exhibited heterogeneous morphology comprising large lamellae 10-20 pm wide. The low-GMA graft content PP seemed slightly more efficient than the high GMA content PP in emulsifying PP/PET blends. The GMA grafting level on PP had very limited effects on the blends' mechanical behavior in the range of GMA graft density provided by the two modified resins investigated.
Journal of Applied Polymer Science, 2002
Two ways of recovering the properties of the scrap plastics poly(ethylene terephthalate) (PET) and highdensity polyethylene (HDPE) were analyzed: (1) blending incompletely segregated polymers with a compatibilizer and (2) blending nonsegregated polymers with a small amount (2 pph) of another compatibilizer. The advancement of the compatibilization reaction in a twin-screw extruder depended on the residence time and intensity of mixing according to melt viscosity measurements and scanning electron microscopy observations. The acceptable mechanical properties for systems with different PET contents were obtained in blends compatibilized with ethylene-glycidyl methacrylate (EGMA) and styrene-ethylene-butylene-styrene grafted with maleic anhydride. For a blend with 75% PET and 25% HDPE, the optimum content of EGMA was determined to be about 4 pph, and a film was produced with this composition. Admixtures present in recycled HDPE migrated to PET during blending and accelerated the hydrolysis of PET. As a result of migration, differences in the mechanical properties of the blends were observed, depending on the brand of recycled HDPE used. EGMA was also successfully used for the improvement of mechanical properties of a nonsegregated mixture based on PET. Tensile properties of two compatibilized PET-rich and HDPE-rich commingled scraps indicated the possibility of using these blends for film extrusion, with potential applications in the packaging of technical products.
Polymer, 2005
Ethylene-propylene rubber (EPR) functionalised with glycidyl methacrylate (GMA) (f-EPR) during melt processing in the presence of a co-monomer, such as trimethylolpropane triacrylate (Tris), was used to promote compatibilisation in blends of polyethylene terephthalate (PET) and f-EPR, and their characteristics were compared with those of PET/f-EPR reactive blends in which the f-EPR was functionalised with GMA via a conventional free radical melt reaction (in the absence of a co-monomer). Binary blends of PETand f-EPR (with two types of f-EPR prepared either in presence or absence of the co-monomer) with various compositions (80/20, 60/40 and 50/50 w/w%) were prepared in an internal mixer. The blends were evaluated by their rheology (from changes in torque during melt processing and blending reflecting melt viscosity, and their melt flow rate), morphology scanning electron microscopy (SEM), dynamic mechanical properties (DMA), Fourier transform infrared (FTIR) analysis, and solubility (Molau) test. The reactive blends (PET/f-EPR) showed a marked increase in their melt viscosities in comparison with the corresponding physical (PET/EPR) blends (higher torque during melt blending), the extent of which depended on the amount of homopolymerised GMA (poly-GMA) present and the level of GMA grafting in the f-EPR. This increase was accounted for by, most probably, the occurrence of a reaction between the epoxy groups of GMA and the hydroxyl/carboxyl end groups of PET. Morphological examination by SEM showed a large improvement of phase dispersion, indicating reduced interfacial tension and compatibilisation, in both reactive blends, but with the Tris-GMA-based blends showing an even finer morphology (these blends are characterised by absence of poly-GMA and presence of higher level of grafted GMA in its f-EPR component by comparison to the conventional GMA-based blends). Examination of the DMA for the reactive blends at different compositions showed that in both cases there was a smaller separation between the glass transition temperatures compared to their position in the corresponding physical blends, which pointed to some interaction or chemical reaction between f-EPR and PET. The DMA results also showed that the shifts in the T g s of the Tris-GMA-based blends were slightly higher than for the conventional GMA-blends. However, the overall tendency of the T g s to approach each other in each case was found not to be significantly different (e.g. in a 60/40 ratio the former blend shifted by up to 4.5 8C in each direction whereas in the latter blend the shifts were about 3 8C). These results would suggest that in these blends the SEM and DMA analyses are probing uncorrelatable morphological details. The evidence for the formation of in situ graft copolymer between the f-EPR and PET during reactive blending was clearly illustrated from analysis by FTIR of the separated phases from the Tris-GMA-based reactive blends, and the positive Molau test pointed out to graft copolymerisation in the interface. A mechanism for the formation of the interfacial reaction during the reactive blending process is proposed.
Engineering, Technology & Applied Science Research, 2022
In this paper, blends of recycled polyethylene terephthalate (r-PET) and high-density polyethylene (HDPE) with and without a compatibilizer were prepared using a Brabender Haake Rheocord at 270°C and 32rpm. Ethylene vinyl acetate was chosen as the compatibilizer and its proportion was set to 5, 7, and 10 wt%. The thermal properties and crystallization behavior were determined by Differential Scanning Calorimetry (DSC). Micromechanical properties were also investigated using a Vickers microindentation tester. The DSC analysis indicates that the melting temperature of r-PET and HDPE in all the blends, compatibilized and uncompatibilized, remains constant and almost the same as those of the pure component. On the other hand, it is shown that the degree of crystallinity of HDPE in the blends calculated by DSC depends on the composition of the polymeric mixture. However, the Hardness (H) decreases with increasing r-PET content until 50/50 composition of r-PET/HDPE is reached, whereas for larger r-PET content values, H increases. The same trend was obtained with the addition of the compatibilizer.
Journal of Applied Polymer Science, 2009
Blends based on recycled high density polyethylene (R-HDPE) and recycled poly(ethylene terephthalate) (R-PET) were made through reactive extrusion. The effects of maleated polyethylene (PE-g-MA), triblock copolymer of styrene and ethylene/butylene (SEBS), and 4,4 0 -methylenedi(phenyl isocyanate) (MDI) on blend properties were studied. The 2% PE-g-MA improved the compatibility of R-HDPE and R-PET in all blends toughened by SEBS. For the R-HDPE/R-PET (70/30 w/w) blend toughened by SEBS, the dispersed PET domain size was significantly reduced with use of 2% PE-g-MA, and the impact strength of the resultant blend doubled. For blends with R-PET matrix, all strengths were improved by adding MDI through extending the PET molecular chains. The crystalline behaviors of R-HDPE and R-PET in one-phase rich systems influenced each other. The addition of PE-g-MA and SEBS consistently reduced the crystalline level (v c ) of either the R-PET or the R-HDPE phase and lowered the crystallization peak temperature (T c ) of R-PET. Further addition of MDI did not influence R-HDPE crystallization behavior but lowered the v c of R-PET in R-PET rich blends. The thermal stability of R-HDPE/R-PET 70/30 and 50/50 (w/w) blends were improved by chain-extension when 0.5% MDI was added.
European Polymer Journal, 2007
A highly novel nano-CaCO 3 supported bnucleating agent was employed to prepare b-nucleated isotactic polypropylene (iPP) blend with polyamide (PA) 66, b-nucleated iPP/PA66 blend, as well as its compatibilized version with maleic anhydride grafted PP (PP-g-MA), maleic anhydride grafted polyethylene-octene (POE-g-MA), and polyethylene-vinyl acetate (EVA-g-MA), respectively. Nonisothermal crystallization behavior and melting characteristics of b-nucleated iPP and its blends were investigated by differential scanning calorimeter and wide angle X-ray diffraction. Experimental results indicated that the crystallization temperature (T p c ) of PP shifts to high temperature in the non-nucleated PP/PA66 blends because of the a-nucleating effect of PA66. T p c of PP and the b-crystal content (K b ) in b-nucleated iPP/PA66 blends not only depended on the PA66 content, but also on the compatibilizer type. Addition of PP-g-MA and POE-g-MA into bnucleated iPP/PA66 blends increased the b-crystal content; however, EVA-g-MA is not benefit for the formation of bcrystal in the compatibilized b-nucleated iPP/PA66 blend. It can be relative to the different interfacial interactions between PP and compatibilizers. The nonisothermal crystallization kinetics of PP in the blends was evaluated by Mo's method.