Rheological study of recycled polypropylene–starch blends

Blends of recycled polypropylene (PP) and starch (S) with the compositions polypropylene 83 wt%–starch 17 wt% (PP83/S17) (blend 1a), polypropylene 68.8 wt%–starch 31.2 wt% (PP 68.8/S 31.2) (blend 2a) and polypropylene 89.5 wt%–starch 10.5 wt% (PP 89.5/S 10.5) (blend 3a) were synthesized. Maleated polypropylene (MAPP) was used as a compatibilizer. The compositions of the compatibilized blends were PP73/S15/MAPP12 (blend 1b), PP55/S25/MAPP20 (blend 2b) and PP85/S10/MAPP5 (blend 3b). The occurrence of a reaction between MAPP and starch was studied using Fourier transform infrared analysis. Thermal and rheological properties such as the complex viscosity, storage and loss modulus of the blends with a compatibilizer were found to be higher than those of the blends without a compatibilizer. The compatibilized and uncompatibilized blends, as well as recycled PP, were characterized using differential scanning calorimetry, thermogravimetric analysis and cone-and-plate rheometry. The storage and loss modulus values of blend 3b were observed to be the best. The best compatibilizing effect was exhibited by blend 3b at a loading of 5 wt% MAPP because this compatibilizer content yielded the highest complex viscosity and visco-elastic behavior. The presence of a functional compatibilizer enhanced the interactions between starch and recycled PP, which was confirmed by a rise in the melt viscosity, storage modulus and thermal stability. These blends were also characterized in terms of their water uptake by performing water absorption tests. Blend 2b containing 20 % MAPP was observed to absorb the maximum amount of water at 25 °C.     

Interfacially compatibilized LDPE/POE blends reinforced with nanoclay: investigation of morphology,rheology and dynamic mechanical properties

Morphological, melt rheological and dynamic mechanical properties of low-density polyethylene (LDPE)/ethylene–octene copolymer (POE)/organo-montmorillonite (OMMT) nanocomposites, prepared via melt compounding were studied. The XRD traces indicated different levels of intercalated structures for the nanocomposites. Addition of a compatibilizer (PE-g-MA) improved the intercalation process. TEM results revealed existence of clay layers in both phases but they were mainly localized in the elastomeric POE phase. Addition of 5 wt% OMMT to the LDPE/POE blend led to reduction in the size of the elastomer particles confirmed by AFM. The complex viscosity and storage modulus showed little effect of the presence of the clay when no compatibilizer was added. As the extent of exfoliation increased with addition of compatibilizer, the linear viscoelastic behavior of the composites gradually changed specially at low-frequency regions. The interfacially compatibilized nanocomposites with 5 wt% OMMT had the highest melt viscosity and modulus among all the studied nanocomposites and blends. Also, this particular composition showed the best improvement in dynamic storage modulus. The results indicated that clay dispersion and interfacial adhesion, and consequently different properties of LDPE/POE/clay nanocomposites, are greatly affected by addition of compatibilizer.     

Effect of starch ratio and compatibilization on the viscoelastic behavior of POE/starch blends

In this research, polyolefin elastomers (POE)/starch blends were prepared using an internal mixer with 0 to 55 wt% starch content, and MAH was added into POE/starch blend to prepare a composite that improves its biodegradation, while tuning the viscoelastic behavior and morphology. The effect of the composition and the compatibilizer addition on properties, such as morphology, rheology, and the creep behavior, was investigated. The observations of microstructures through thescanning electron microscope (SEM) showed that in the incompatibilized blends, the interfacial adhesion of the phases was very weak. In contrast, in compatibilized samples, the broken surface of starch was observed confirming the enhanced interfacial tension. Additionally, the increase in the starch content led to the rise in the relaxation times. The creep test results revealed that with the increment of starch content, the creep of the blends increased. The compatibilizer improved the creep recovery of the blends. Moreover, by addition of the compatibilizer, the values of the creep parameters including η, E₁, E_2, and τ_R obtained from the standard linear solid model (SLS), was higher than those for the incompatibilized blends. The addition of POE-MA compatibilizer can improve the properties of POE/starch blends, while keeping their biocompatibility. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48877.     

Toughened polyoxymethylene by polyolefin elastomer and glycidyl methacrylate grafted high‐density polyethylene

Ternary blends of polyoxymethylene (POM), polyolefin elastomer (POE), and glycidyl methacrylate grafted high density polyethylene (GMA‐g‐HDPE) with various component ratios were studied for their mechanical and thermal properties. The size of POE dispersed phase increased with increasing the elastomer content due to the observed agglomeration. The notched impact strength demonstrated a parabolic tendency with increasing the elastomer content and reached the peak value of 10.81 kJ/m² when the elastomer addition was 7.5 wt%. The disappearance of epoxy functional groups in the POM/POE/GMA‐g‐HDPE blends indicated that GMA‐g‐HDPE reacted with the terminal hydroxyl groups of POM and formed a new graft copolymer. Higher thermal stability was observed in the modified POM. Both storage modulus and loss modulus decreased from dynamic mechanical analysis tests while the loss factor increased with increasing the elastomer content. GMA‐g‐HDPE showed good compatibility between the POM matrix and the POE dispersed phase due to the reactive compatibilization of the epoxy groups of GMA and the terminal hydroxyl groups of POM. A POM/POE blend without compatibilizer was researched for comparison, it was found that the properties of P‐7.5(POM/POE 92.5 wt%/7.5 wt%) were worse than those of the blend with the GMA‐g‐HDPE compatibilizer. POLYM. ENG. SCI., 57:1119–1126, 2017. © 2017 Society of Plastics Engineers     

Influence of a compatibilizer on the properties of polyethylene–octene elastomer/starch blends

The effect of a compatibilizer on the properties of corn starch‐reinforced metallocene polyethylene–octene elastomer (POE) blends was studied. The compatibility between POE and starch was improved markedly with an acrylic acid‐grafted POE (POE‐g‐AA) copolymer as a compatibilizer. Fourier transform infrared spectroscopy, X‐ray diffraction spectroscopy, differential scanning calorimetry, and scanning electron microscopy were used to examine the blends produced. The size of the starch phase increased with an increasing content of starch for noncompatibilized and compatibilized blends. The POE/starch blends compatibilized with the POE‐g‐AA copolymer lowered the size of the starch phase and had a fine dispersion and homogeneity of starch in the POE matrix. This better dispersion was due to the formation of branched and crosslinked macromolecules because the POE‐g‐AA copolymer had anhydride groups to react with the hydroxyls. This was reflected in the mechanical properties of the blends, especially the tensile strength at break. In a comparison with pure POE, the decrease in the tensile strength was slight for compatibilized blends containing up to 40 wt % starch. The POE‐g‐AA copolymer was an effective compatibilizer because only a small amount was required to improve the mechanical properties of POE/starch blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1792–1798, 2002     

Correlation of morphology and rheological response of interfacially modified PTT/m-LLDPE blends with varying extent of modification

Morphology and rheology of poly(trimethylene terephthalate)/metallocene linear low-density polyethylene (PTT/m-LLDPE) immiscible blends with varying extent of compatibilization were experimentally examined and theoretically analyzed using Palierne and Coran models. A glycidyl methacrylate-based terpolymer was used to modify the interface of the blend. The particle radius in the PTT75/m-LLDPE25 system decreases in proportion to the level of added compatibilizer up to 5 wt% of terpolymer, beyond which the particle size remains unchanged. This is attributed to the saturation of interface by interfacial modifier leading to diminish the effectiveness of the compatibilizer. Morphological observations reveal that the saturation of the interface for PTT25/m-LLDPE75 system occurs at 2.5 wt% compatibilizer content. Rheological examinations show a sharp reduction of complex viscosity for the latter system at 10 wt% terpolymer which is ascribed to the micelle formation in the bulk phase. Plots of the relaxation time spectrum exhibit that upon addition of the compatibilizer the magnitude of the relaxation peaks associated with interface increases which is ascribed to the increase of the interfacial area. The Palierne model fails to predict admissible values and reasonable trend for interfacial tension. This failure is believed to be due to the excessively large difference between the complex shear modulus values of the dispersed and matrix phases. However, the Coran model used to describe the dynamic moduli, shows a good fit to the experimental data.     

Polyethylene-octene elastomer/starch blends: miscibility,morphology and mechanical properties

In this paper, polyethylene-octene elastomer (POE) and starch blends were studied. The compatibility beyween POE and starch was improved by adding polyethylene-octene/maleic anhydride graft copolymer (POE-MA) as compatibilizer. The compatibilization reaction was followed by FTIR spectra. The morphology of the blends was investigated using scanning electron microscopy (SEM). It was found that the size of the starch phase increased with an increasing content of starch for the blends. The addition of POE-MA can lower the size of the starch phase in the POE matrix, and this was due to the formation of an ester carbonyl function group by the chemical reaction between the anhydride groups and hydroxyl groups on starch. This was reflected in the mechanical properties of the blends, the addition of POE-MA compatibilizer can improve the mechanical properties of POE/starch blends. The thermogravimetric analysis of POE/starch blends was also conducted.     

Polymer blends of polyethersulfone with all aromatic liquid crystalline co-polyester

Polymer blends of polyethersulfone (PES) with an all aromatic liquid crystalline co-polyester (LCP) were investigated. In addition, PES oligomers with the reactive functions end groups (?ONa) were added as a third component to the above blends in order to improve their properties. Flexural properties, such as modulus and strength, and dynamic viscoelastic properties, such as dynamic storage elasticity (E′) and loss tangent (tan δ), of the blends were measured. The morphology of blends was characterized using a differential scanning calorimeter (DSC) and a scanning electron microscope (SEM). Of the flexural properties, the modulus of PES increased almost linearly with increasing LCP content. However, strength decreased as LCP content increased to 20 wt%. In contrast, the addition of the PES oligomers had little effect on modulus, but strength was clearly improved. Regarding dynamic viscoelastic properties, the oligomer-containing blends exhibited complex behavior. Regarding morphologies, SEM analysis revealed that the LCP was not fibrous in the core of the blend containing 40 wt% or less, but the addition of the PES oligomers made LCP fibrous even in blends with low LCP content. It was concluded that the PES oligomers with reactive functional groups acted as a compatibilizer in polymer blends of PES/LCP.     

Dynamic rheological behavior and mechanical properties of PVC/ACS blends

In order to increase the processability and mechanical properties of poly(vinyl chloride) (PVC), the terpolymer of acrylonitrile-chlorinated polyethylene-styrene (ACS) is used to modify the PVC. The plasticizing, rheological, and dynamic mechanical properties of PVC/ACS blends are investigated by means of torque rheometer, oscillation rheometer, and dynamic mechanical analyzer. The measurements of torque rheometer showed that both plasticizing time and stabilization torque are decreased with increasing ACS content. The PVC/ACS melts displayed larger dynamic storage modulus (G′), loss modulus (G′′), and complex viscosity (η*) than that of pure PVC, and these values reached maximum for the blend with 10 wt% ACS. When ACS content was below 10 wt%, PVC and ACS showed good compatibility in the blends by displaying a single T _g; however, when ACS content was more than 15 wt%, the phase separation phenomena occurred in the blends. PVC/ACS blends showed larger storage modulus (E′) and loss modulus (E′′) than that of pure PVC, but these values decreased with increasing ACS content. ACS can enhance both tensile and impact strength of PVC, and the impact strength reached maximum with 15 wt% ACS content which is higher 2.5 kJ/m² than the pure PVC. These results suggested that ACS is an efficient processing aid and toughening modifier for PVC at appropriate content.     

Mechanical Properties and Compatibility of Sulfonated Poly(Ethylene Terephthalate)/Cyclic Olefin Copolymer/Maleic Anhydride-Grafted Polyethylene-Octene Elastomer

A compatibilizer was added to blends of sulfonated poly(ethylene terephthalate) (SPET) and cyclic olefin copolymer (COC) and the effects were studied. The compatibilizer was maleic anhydride-grafted polyethylene-octene elastomer (POE-g-MA). It was hoped that maleic anhydride (MA) would react with carbonyl groups in the SPET molecules, owing to POE and COC being olefinic polymers and therefore compatible with each other. The compatibilization effects of the 80SPET/20COC/15POE-g-MA composite were measured using a dynamic mechanical analyzer (DMA) and scanning electron microscopy (SEM). Mechanical properties and rheological behavior were also studied. The results showed that there are partial compatibilizations for SPET/POE-g-MA and SPET/COC cases. Because POE-g-MA > COC > SPET in viscosity, COC in SPET has particle size 1–3 μm and POE-g-MA has particle size 5–30 μm, both resulting in almost no difference in impact strength.     

Evolution of properties in ABS/PA6 blends compatibilized by fixed weight ratio SAGMA copolymer

Blends of acrylonitrile-butadiene-styrene (ABS) and Nylon 6 (PA6) incorporating styrene-acrylonitrile-glycidyl methacrylate (SAGMA) copolymer as compatibilizer have been studied across five different compositions by varying the PA6 ratio from 15 wt% to 55 wt%. The evolution of morphology from discrete dispersed PA6 particles to phase inversion to co-continuous phases effected due to the compatibilizer have been studied vis-à-vis preliminary melt flow analysis, viscoelastic behavior, physico-mechanical and thermal properties of the blends. Single point viscosity measurements during melt flow analyses are indicative of a significant increase in viscosity upon initial incorporation of PA6 followed by narrow increases with content. It is observed that while there are gradual positive modifications in physico-mechanical properties with increasing PA6 content, the most significant improvements are observed for room temperature izod impact strength and break elongation effected in the region of phase inversion on to the formation of a co-continuous phase. The low temperature impact strength at −40 °C essentially remains comparable to that of control ABS. DMTA analysis evidences partial dissolution of the blend components by the shifts of the damping peaks (Tg) of PB rich phase, SAN and PA6. Broadening of the damping peak of PB rich phase of ABS is attributed to increasing interfacial region due to PA6-g-SAGMA molecular layer at the interface. Thermal stability of the blends were not significantly affected in comparison to control ABS and PA6.     

Studies on impact‐modified nylon 6/ABS blends

The objective of this research is to study the effect of using maleic anhydride‐grafted polyethylene‐octene elastomer (POE‐g‐MA) as a compatibilizer on nylon 6/acrylonitile‐butadiene‐styrene (ABS) copolymer blends. With POE‐g‐MA, nylon 6/ABS at a blending ratio of 80/20 showed an optimal result in modified impact property. Scanning electron microscopy (SEM) revealed that the particle sizes of ABS in the dispersed phase diminished as the amount of the added compatibilizer (POE‐g‐MA) increased. The compatibilizer reduced the surface tension between nylon 6 and ABS, thus increasing the compatibility of the two phases. Furthermore, studies of the rheological behavior of the system showed that the shear viscosity of nylon 6/ABS blends also increased with the introduction of POE‐g‐MA. Finally, dynamic mechanical analysis (DMA) experiments showed that adding POE‐g‐MA dramatically improved the impact strength of the blends at room temperature and low temperatures. Polym. Eng. Sci. 44:2340–2345, 2004. © 2004 Society of Plastics Engineers.     

Improvement in impact resistance of polylactic acid by masticated and compatibilized natural rubber

Mastication is the technique widely used to reduce viscosity of natural rubber and the higher mastication speed leads to lower NR viscosity. The optimum viscosity of NR that could provide high impact strength for the blends depends largely on the blending time and method. This study is focused on the enhancement of impact strength of polylactic acid (PLA) blended with masticated natural rubber (NR) using sorbitan ester (SE), a biodegradable food additive, as a compatibilizer. The effects of NR mastication, compatibilizer and NR contents and the mixture’s viscosity on the morphological, thermal and impact properties of PLA/NR blends were investigated in relation to the changes in the morphology, thermal properties and impact strength of PLA/NR blends. It was found that the optimum viscosity of NR that provided the highest impact strength to the blends was achieved when NR was masticated at 40 rpm for 15 min. The highest impact strength corresponded well not only with the small NR phase size, but also with the highest crystallization rate. For the effect of compatibilizer, it was found that a small amount of SE could more than double the impact strength of the blends, where the optimum compatibilizer content was 0.5 wt%. Interestingly, the high impact strength of the blends in all cases was accompanied by short interparticle distance and slightly higher percent crystallinity.     

PA6／POE／EAA共混体系的相态与性能的研究

采用乙烯－1－辛烯共聚物弹性体（POE）为增韧剂、乙烯－甲基丙烯酸共聚物（EAA）作为增溶剂制备了以尼龙6（PA6）为基体的PA6／POE／EAA共混合金。详细研究了弹性体用量与共混体系的亚微观相态、力学性能和流变性能的关系。结果表明随着弹性体含量的增加，共混体系的分散相粒子尺寸大小没有明显变化，共混体系的冲击强度增加，拉伸强度和弯曲弹性模量降低。弹性体的增加使体系的熔体粘度降低，改善了体系的加工性能，但当POE增加到20％时，随着POE的增加，粘度不再下降。     

Rheology‐morphology correlation in PET/PP blends: Influence of type of compatibilizer

Rheological and morphological properties of melt processed poly(ethylene terephthalate) (PET)/polypropylene (PP) blends are presented. Two types of compatibilizer namely, PP‐g‐MA <MA= maleic anhydtide> and Elvaloy PTW, an n‐butyl acrylate glycidyl methacrylate ethylene terpolymers, were incorporated at different levels to the PET/PP blend system. Scanning electron microscopy revealed that the dispersed particle sizes were smaller in PET‐rich blends than PP‐rich blends. With increasing compatibilizer level, the refinement of morphology was observed in both the systems. However, the blends compatibilized with PTW showed a more refined (smaller) particle size, and at high PTW content (10 wt%), the morphology changed towards monophasic. The significant changes in morphology were attributed to the highly reactive nature of PTW. Investigation of rheological properties revealed that the viscosity of the PET/PP blends followed typical trends based on mixing rule, which calculates the properties of blends based on a linear average. Incorporation of PP‐g‐MA into the blends resulted in a negative deviation in the viscosity of the system with respect to that of the neat blend. With increasing PP‐g‐MA level, the deviation became more pronounced. Although incorporation of the compatibilizer into the PET/PP blends refined the morphology, it led to a drastic drop of viscosity, which could be attributed to inherently lower molecular weight of the compatibilizer. In the case of the blends compatibilized by PTW, a strong positive deviation in rheological properties was observed that confirmed the stronger interaction between the blend components due to reactive compatibilization process, which led to the more refined morphology in this series of blends. J. VINYL ADDIT. TECHNOL., 19:25–30, 2013. © 2013 Society of Plastics Engineers     

rPET/POE/LDPE-g-AA复合材料的制备及性能

以回收聚对苯二甲酸乙二酯( rPET)为基体材料,乙烯-辛烯共聚物(POE)为增韧材料,丙烯酸接枝低密度聚乙烯( LDPE-g-AA)为增容剂,制备了rPET/POE/LDPE-g-AA复合材料.分析了POE、LDPE-g-AA对rPET 玻璃化转变温度、断面相结构、结晶性能、力学性能的影响.结果表明,加入POE...     

Transition of phase continuity induced by crosslinking and interfacial reaction during reactive processing of compatibilized PVC/SBR blends

Blends of 50 wt% of poly(vinyl chloride) (PVC) and 40 wt% of styrene butadiene rubber (SBR) with 10 wt% of acrylonitrile butadiene rubber (NBR) as the compatibilizer were prepared in a Haake mixer. An inversion of phase continuity was observed when the sulfur concentration was changed from 0.0 to 2.0 parts per hundred parts of resins (phr) in the blends containing an NBR with an acrylonitrile content of 29.5 wt% (NBR-29). The SBR phase, which is continuous in the unvulcanized blend, changes progressively into the dispersed phase as sulfur concentration increases. This is explained by the viscosity increase of the rubber caused by crosslinking. There is no phase inversion as a result of increasing sulfur concentration when the compatibilizer NBR-29 was replaced by an NBR with an acrylonitrile content of 40 wt% (NBR-40). The SBR phase is discrete in the unvulcanized blend with NBR-40 as the compatibilizer.

A change in phase continuity occurs during processing of the vulcanized PVC/NBR-29/SBR (50/10/40) blends. A torque peak in the torque curve during processing is correlated to the transition of the PVC phase continuity. There is a gradual increase in the torque curve after the torque peak. The rubber particle size decreases as a result of such a post-peak increase in the torque. The torque peak and the post-peak increase in the torque are absent in the case of the binary blends (PVC/NBR and PVC/SBR). The post-peak increase in the torque is attributed to the interfacial reaction between SBR and NBR that resides in the PVC phase.

A novel method developed recently was applied to study the interface development during processing. An interface with a higher rubber concentration develops during processing of the compatibilized blends.     

Morphology and rheological properties of compatibilized low‐density polyethylene/linear low‐density polyethylene/thermoplastic starch blends

Morphology and rheological properties of low‐density polyethylene/linear low‐density polyethylene/thermoplastic starch (LDPE/LLDPE/TPS) blends are experimentally investigated and theoretically analyzed using rheological models. Blending of LDPE/LLDPE (70/30 wt/wt) with 5–20 wt % of TPS and 3 wt % of PE‐grafted maleic anhydride (PE‐g‐MA) as a compatibilizer is performed in a twin‐screw extruder. Scanning electron micrographs show a fairly good dispersion of TPS in PE matrices in the presence of PE‐g‐MA. However, as the TPS content increases, the starch particle size increases. X‐ray diffraction patterns exhibit that with increase in TPS content, the intensity of the crystallization peaks slightly decreases and consequently crystal sizes of the blends decrease. The rheological analyses indicate that TPS can increase the elasticity and viscosity of the blends. With increasing the amount of TPS, starch particles interactions intensify and as a result the blend interface become weaker which are confirmed by relaxation time spectra and the prediction results of emulsion Palierne and Gramespacher‐Meissner models. It is demonstrated that there is a better agreement between experimental rheological data and Coran model than the emulsion models. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44719.     

Effect of the compatibilizer on the morphology and properties of dynamically cured PP/POE/epoxy blends

Dynamic vulcanization was successfully applied to epoxy resin reinforced polypropylene (PP)/ethylene‐octene copolymer (POE) blends, and the effects of different compatibilizers on the morphology and properties of dynamically cured PP/POE/epoxy blends were studied. The results show that dynamically cured PP/POE/epoxy blends compatibilized with maleic anhydride‐grafted polypropylene (MAH‐g‐PP) have a three‐phase structure consisting of POE and epoxy particles dispersed in the PP continuous phase, and these blends had improved tensile strength and flexural modulus. While using maleic anhydride‐grafted POE (MAH‐g‐POE) as a compatibilizer, the structure of the core‐shell complex phase and the PP continuous phase showed that epoxy particles could be embedded in MAH‐g‐POE in the blends, and gave rise to an increase in impact strength, while retaining a certain strength and modulus. DSC analysis showed that the epoxy particles in the blends compatibilized with MAH‐g‐PP were more efficient nucleating agents for PP than they were in the blends compatibilized with MAH‐g‐POE. WAXD analysis shows that compatibilization do not disturb the crystalline structure of PP in the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Morphology and rheological properties of blends of chemically modified thermoplastic starch and polycaprolactone

Polycaprolactone (PCL) was blended in a twin‐screw extruder with chemically modified thermoplastic starch (CMPS) to provide biobased and biodegradable resin composition. Reacting starch with maleic anhydride (MA) in the presence of a plasticizer and a free radical initiator provided the CMPS. The starch modification improved interfacial adhesion and processability in blending with other thermoplastic polyesters. The rheological, mechanical, thermal, and morphological properties of the blends were examined. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) studies revealed that the PCL/CMPS blends are thermodynamically immiscible. However, they formed compatible blends due to the reaction of the carboxyl groups on starch backbone with hydroxyl groups of the PCL chain ends. The tensile strength and elongation decreased with increasing CMPS content, whereas the modulus increased. Dynamic viscoelastic measurements showed that the flow behavior of PCL was that of Newtonian fluid within the tested frequencies, whereas the CMPS exhibited strong shear thinning characteristics. The flow behavior of the blends varied with the CMPS content. The complex viscosity, storage, and loss moduli of the blends containing more than 40% of CMPS were higher than those of pure CMPS and PCL. In addition, the properties of CMPS to those of chemically unmodified thermoplastic starch (TPS) were compared. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers