Effect of epoxy functionalized compatibilizer on the mechanical properties of low‐density polyethylene/plasticized tapioca starch blends

A series of low‐density polyethylene (LDPE) blends with varying proportions of plasticized tapioca starch have been used for the study of their mechanical properties. A functionalized epoxy resin, namely, poly(ethylene‐co‐glycidyl methacrylate) has been used as the compatibilizer. The impact and tensile properties have been measured by standard ASTM methods. The mechanical properties are seen to improve significantly with the addition of the epoxy compatibilizer, approaching values close to those of virgin LDPE. The scanning electron micrographs of the compatibilized blends show ductile failure which evidently contribute to improved mechanical properties. © 2001 Society of Chemical Industry     

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.     

Mechanical properties of esterified tapioca starch–LDPE blends using LDPE‐co‐glycidyl methacrylate as compatibilizer

Studies on the mechanical properties of acetylated and phthalated starch blends with low density polyethylene (LDPE) were performed with and without LDPE‐co‐glycidyl methacrylate copolymer as compatibilizer. Impact and tensile properties of the blend specimens were measured following standard ASTM methods. Thermogravimetric analysis of esterified starches and of the blends were also conducted. Scanning electron microscopy was used to analyze the fractured and unfractured blends. Results indicate a significant improvement in the mechanical properties by starch esterification, which is further enhanced by the addition of the compatibilizer. Copyright © 2004 Society of Chemical Industry     

Thermal and mechanical properties of linear low‐density polyethylene/low‐density polyethylene/wax ternary blends

The thermal and mechanical properties of uncrosslinked three‐component blends of linear low‐density polyethylene (LLDPE), low‐density polyethylene (LDPE), and a hard, paraffinic Fischer–Tropsch wax were investigated. A decrease in the total crystallinity with an increase in both LDPE and wax contents was observed. It was also observed that experimental enthalpy values of LLDPE in the blends were generally higher than the theoretically expected values, whereas in the case of LDPE the theoretically expected values were higher than the experimental values. In the presence of higher wax content there was a good correlation between experimental and theoretically expected enthalpy values. The DSC results showed changes in peak temperature of melting, as well as peak width, with changing blend composition. Most of these changes are explained in terms of the preferred cocrystallization of wax with LLDPE. Young's modulus, yield stress, and stress at break decreased with increasing LDPE content, whereas elongation at yield increased. This is in line with the decreasing crystallinity and increasing amorphous content expected with increasing LDPE content. Deviations from this behavior for samples containing 10% wax and relatively low LDPE contents are explained in terms of lower tie chain fractions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1748–1755, 2005     

Mechanical and thermal properties of poly(lactic acid)/starch blends with dioctyl maleate

Poly(lactic acid) (PLA)/starch blends were prepared blending with dioctyl maleate (DOM). DOM acted as a compatibilizer at low concentrations (below 5%), and markedly improved tensile strength of the blend. However, DOM functioned as a plasticizer at concentrations over 5%, significantly enhancing elongation. Compatibilization and plasticization took place simultaneously according to the analysis of, for example, mechanical properties and thermal behavior. With DOM as a polymeric plasticizer, thermal loss in the blends was not significant. Water absorption of PLA/starch blends increased with DOM concentration. DOM leaching in an aqueous environment was inhibited. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1697–1704, 2004     

Mechanical and thermal properties of LDPE‐cellulose acetate phthalate blends—Effect of maleic anhydride‐grafted LDPE compatibilizer

Biodegradable blends of LDPE and cellulose acetate phthalate have been prepared. Maleic anhydride‐grafted LDPE has been added as a compatibilizer to this blend. The elastic modulus and tensile strength has been considerably improved by adding LDPE‐g‐maleic anhydride compatibilizer. Scanning electron microscope micrographs reflected the observed results for the increase in mechanical properties of the blend. Further blend morphology exhibited a deformed matrix for the compatibilized blends. Thermogravimetric analysis studies showed two‐stage degradation for the blends. Differential scanning calorimetry thermograms showed a loss of crystallinity for the LDPE phase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Blends of LDPE/chitosan using epoxy‐functionalized LDPE as compatibilizer

LDPE and chitosan blends were prepared using an epoxy‐functionalized polyethylene as compatibilizing agent for improving interfacial adhesion. Compatibilization improved both tensile and flexural properties (with values approaching close to that of neat LDPE) when compared with that of uncompatibilized blends. However, the elongation at break reduced due to the addition of rigid chitosan. Thermogravimetric analysis showed a two‐stage degradation, while differential scanning calorimetry exhibited reduced crystallinity for compatibilized blends. Biodegradation studies revealed increased biodegradability with increase in chitosan loading. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of cellulose nanofibers and acetylated cellulose nanofibers on the properties of low‐density polyethylene/thermoplastic starch blends

The aim of this study was to evaluate the effect of cellulose nanofibers (CNFs) and acetylated cellulose nanofibers (ACNFs) on the properties of low‐density polyethylene/thermoplastic starch/polyethylene‐grafted maleic anhydride (LDPE/TPS/PE‐g‐MA) blends. For this purpose, CNFs, isolated from wheat straw fibers, were first acetylated using acetic anhydride in order to modify their hydrophilicity. Afterwards, LDPE/TPS/PE‐g‐MA blends were reinforced using either CNFs or ACNFs at various concentrations (1–5 wt%) with a twin‐screw extruder. The mechanical results demonstrated that addition of ACNFs more significantly improved the ultimate tensile strength and Young's modulus of blends than addition of CNFs, albeit elongation at break of both reinforced blends decreased compared with the neat sample. Additionally, biodegradability and water absorption capacity of blends improved due to the incorporation of both nanofibers, these effects being more pronounced for CNF‐assisted blends than ACNF‐reinforced counterparts. © 2018 Society of Chemical Industry     

Mechanical properties of uncrosslinked and crosslinked linear low‐density polyethylene/wax blends

The mechanical properties of uncrosslinked and crosslinked linear low‐density polyethylene (LLDPE)/wax blends were investigated, using differential scanning calorimetry (DSC), tensile testing, and melt flow indexing. A decrease in the degree of crystallinity, as determined from the DSC melting enthalpies, was observed with an increase in the dicumyl peroxide (DCP) concentration. The Young's modulus increased with increased wax portions, and there was a higher increase for crosslinked blends. The yield stress generally decreased with increased peroxide content. Crosslinking caused an increase in elongation at yield, but increased wax content caused a decrease in elongation at yield. The stress at break generally increased with increasing peroxide content, but it decreased with increased wax content. The elongation at break decreased with an increase in the DCP concentration. Melt flow rate measurements indicated a mutual miscibility in LLDPE/wax blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 973–980, 2001     

Mechanical and morphological characterization of starch/zein blends plasticized with glycerol

Blends of starch and zein plasticized with glycerol were prepared by melting in a batch mixer at 160°C. Glycerol was used as plasticizer in contents ranging from 20 to 40 wt % with respect to the starch/zein matrix. These blends were characterized by mechanical tests, dynamic mechanical analysis, and optical microscopy. In tensile tests, the Young's modulus and ultimate tensile strength increased with increasing zein content for all compositions, whereas elongation at break decreased sharply with increasing zein content up to 20%, and it remained nearly constant at higher contents of zein, which increased the stiffness of the blends. On the other hand, increase in the glycerol content caused a decrease in mechanical resistance of the blends. Storage modulus increased with increasing zein content and the tan δ curves showed that the blends exhibited two distinct glass transitions, one for each component, indicating a two‐phase system, confirming the morphological evidence of micrographs that displayed two separate phases. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4133–4139, 2006     

Mechanical and thermal properties of high‐density polyethylene toughened with glass beads

Glass beads were used to improve the mechanical and thermal properties of high‐density polyethylene (HDPE). HDPE/glass‐bead blends were prepared in a Brabender‐like apparatus, and this was followed by press molding. Static tensile measurements showed that the modulus of the HDPE/glass‐bead blends increased considerably with increasing glass‐bead content, whereas the yield stress remained roughly unchanged at first and then decreased slowly with increasing glass‐bead content. Izod impact tests at room temperature revealed that the impact strength changed very slowly with increasing glass‐bead content up to a critical value; thereafter, it increased sharply with increasing glass‐bead content. That is, the Izod impact strength of the blends underwent a sharp transition with increasing glass‐bead content. It was calculated that the critical interparticle distance for the HDPE/glass‐bead blends at room temperature (25°C) was 2.5 μm. Scanning electron microscopy observations indicated that the high impact strength of the HDPE/glass‐bead blends resulted from the deformation of the HDPE matrix. Dynamic mechanical analyses and thermogravimetric measurements implied that the heat resistance and heat stability of the blends tended to increase considerably with increasing glass‐bead content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2102–2107, 2003     

Low density polyethylene and grafted lignin polyblends using epoxy‐functionalized compatibilizer: mechanical and thermal properties

Lignin was graft copolymerized with methyl methacrylate using manganic pyrophosphate as initiator. This modified lignin was then blended (up to 50 wt%) with low density polyethylene (LDPE) using a small quantity of poly[ethylene‐co‐(glycidyl methacrylate)] (PEGMA) compatibilizer. The mechanical properties of the blend were substantially improved by using modified lignin in contrast to untreated lignin. Differential scanning calorimetry studies showed loss of crystallinity of the LDPE phase owing to the interaction between the blend components. Thermogravimetric analysis showed higher thermal stability of modified lignin in the domain of blend processing. This suggested that there is scope for useful utilization of lignin, which could also lead to the development of eco‐friendly products. Copyright © 2005 Society of Chemical Industry     

Effects of polyethylene‐grafted maleic anhydride (PE‐g‐MA) on thermal properties,morphology, and tensile properties of low‐density polyethylene (LDPE) and corn starch blends

The effects of polyethylene‐grafted maleic anhydride (PE‐g‐MA) on the thermal properties, morphology, and tensile properties of blends of low‐density polyethylene (LDPE) and corn starch were studied with a differential scanning calorimeter (DSC), scanning electron microscope (SEM), and Instron Universal Testing Machine, respectively. Corn starch–LDPE blends with different starch content and with or without the addition of PE‐g‐MA were prepared with a lab‐scale twin‐screw extruder. The crystallization temperature of LDPE–corn starch–PE‐g‐MA blends was similar to that of pure LDPE but higher than that of LDPE–corn starch blends. The interfacial properties between corn starch and LDPE were improved after PE‐g‐MA addition, as evidenced by the structure morphology revealed by SEM. The tensile strength and elongation at break of corn starch–LDPE–PE‐g‐MA blends were greater than those of LDPE–corn starch blends, and their differences became more pronounced at higher starch contents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2904–2911, 2003     

Improving low‐density polyethylene/poly(ethylene terephthalate) blends with graft copolymers

Blends of low‐density polyethylene (LDPE) and poly(ethylene terephthalate) (PET) were prepared with different weight compositions with a plasticorder at 240°C at a rotor speed of 64 rpm for 10 min. The physicomechanical properties of the prepared blends were investigated with special reference to the effects of the blend ratio. Graft copolymers, that is, LDPE‐grafted acrylic acid and LDPE‐grafted acrylonitrile, were prepared with γ‐irradiation. The copolymers were melt‐mixed in various contents (i.e., 3, 5, 7, and 9 phr) with a LDPE/PET blend with a weight ratio of 75/25 and used as compatibilizers. The effect of the compatibilizer contents on the physicomechanical properties and equilibrium swelling of the binary blend was investigated. With an increase in the compatibilizer content up to 7 phr, the blend showed an improvement in the physicomechanical properties and reduced equilibrium swelling in comparison with the uncompatibilized one. The addition of a compatibilizer beyond 7 phr did not improve the blend properties any further. The efficiency of the compatibilizers (7 phr) was also evaluated by studies of the phase morphology (scanning electron microscopy) and thermal properties (differential scanning calorimetry and thermogravimetric analysis). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Moisture‐sorption characteristics of starch/low‐density polyethylene films

Moisture‐sorption characteristics of starch/low‐density polyethylene (LDPE) blends were carried out at 27°C for water activity (a_w) from 0.1 to 0.9. The sorption data were used to fit six different sorption isotherm models proposed in the literature. The model constants were determined by linear fitting of the sorption equations. The ranges of applicability of water activity for the isotherm models reported in the article lies between 0.1 and 0.4 (monomolecular layer) for the BET model and between 0.3 and 0.9 (multimolecular and capillary condensation layers) for other models. The value of the coefficient of determination (R² = 0.97 ± 0.02) confirms the linear fitting of the equations studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1193–1202, 2002; DOI 10.1002/app.10417     

Preparation and characterization of low‐density polyethylene/banana starch films containing compatibilizer and photosensitizer

Composite films containing various percentages of banana starch and low‐density polyethylene (LDPE) were prepared. The effects of the compatibilizer, banana starch content, and photosensitizer content on the thermal and tensile properties of these films were investigated. The banana starch content was varied from 5 to 20 wt % of LDPE, whereas benzophenone was added as a photosensitizer in three different amounts (0.25, 0.5, and 1 wt %) based on LDPE. In these films PE‐graft‐maleic anhydride (PE‐g‐MA) was used as a compatibilizer at 10 wt % banana starch. It was found that the thermal stability of the composite films remained unchanged with respect to the amount of banana starch and benzophenone content. The addition of banana starch had no effect on the melting temperature and degree of crystallinity of the films. Similarly, PE‐g‐MA had no effect on the melting temperature but decreased the degree of crystallinity of the LDPE phase. Benzophenone caused an increase in the melting temperature but decreased the degree of crystallinity of LDPE in the films. Increasing the amount of banana starch decreased the tensile properties of the composite films. The addition of PE‐g‐MA as a compatibilizer increased the tensile properties compared with the uncompatibilized films. However, benzophenone had no effect on the tensile properties of the blend films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2717–2724, 2006     

Effect of propylation of starch with different degrees of substitution on the properties and characteristics of starch‐low density polyethylene blend films

Corn starch was modified by propylation and degree of substitution (DS) of four starch modifications were 0.61, 1.56, 2.27, and 2.51. Different films were prepared by blending native and propylated starch with low‐density polyethylene (LDPE). The mechanical properties, thermal properties, water absorption capacity, and biodegradability of the blend films varied with the quantity of starch as well as DS. Tensile strength, elongation, and melt flow index of propylated starch blend films were higher compared to the corresponding native starch blend film. These properties improved with increase in DS from 1.56 to 2.51. Propylated starch blend films were found thermally stable than native starch blend films. There was a decrease in water absorption capacity for the films containing propylated starch at high DS. Enzymatic and soil burial degradation results showed that biodegradability of starch‐LDPE films increased with the increase in the starch concentration but it decreased with increase in the DS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Biodegradation of low‐density polyethylene/thermoplastic starch foams before and after electron beam irradiation

Foamy low‐density polyethylene/plasticized starch (LDPE/PLST) blends at different compositions were produced in the presence of azodicarbonamide (ACA) compound as foaming agent. The LDPE/PLST blends before and after electron beam irradiation were investigated in terms of mechanical properties, bulk density, and structure morphology. Moreover, the biodegradability of these materials was evaluated by the soil burial test for 2 months, in which the buried sheets were also examined by scanning electron microscopy (SEM). The results showed that the increase of PLST content from 24 to 30% was accompanied by a decrease in the yield and break stresses of 10 and 20% for the unirradiated blends without the foaming agent, respectively. Further decrease in these mechanical parameters was observed after the foaming process. The bulk density, void fraction, cell size measurements as well as the examination by SEM illustrate clearly the cell growth of the foam structure. The soil burial test and SEM micrographs indicate the growth of microorganisms overall the blend sheets and that the blend was completely damaged after two months of burying. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Evaluation of the thermal and mechanical properties of poly(ε‐caprolactone), low‐density polyethylene,and their blends

The thermal and mechanical properties of low‐density polyethylene (LDPE), poly(ε‐caprolactone) (PCL), and their blends were evaluated. Differential scanning calorimetry showed that increasing the PCL content of the blend did not change the LDPE melting temperature, but reduced the crystallinity by up to 16.8%. This behavior was related to interactions between the PCL chains and the crystalline phase of LDPE. Tensile strength and elongation at break values for the blends were lower than those for the pure polymers, which suggested an incompatibility between the polymers. The values for Young's modulus under tensile increased when PCL was added to LDPE. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3909–3914, 2004     

Influence of maleic anhydride on the compatibility of thermal plasticized starch and linear low‐density polyethylene

In the presence of dicumyl peroxide, the compatibility of thermal plasticized starch/linear low‐density polyethylene (TPS/LLDPE) blends using maleic anhydride (MAH) as compatibilizer was investigated. The thermal plasticization of starch and its compatibilizing modification with LLDPE was accomplished in a single‐screw extruder at the same time. We prepared three types of blends containing different percentages of TPS and MAH. The content of MAH based on LLDPE was 0, 1, and 2 wt %, respectively. The morphology of the blends was studied by SEM. It was found that, with the addition of MAH, the blends have good interfacial adhesion and finely dispersed TPS and LLDPE phases, which is reflected in the mechanical and thermal properties of the blends. The blends containing MAH showed higher tensile strength, elongation at break, and thermal stability than those of blends without MAH. The rheologic properties of the blends demonstrated the existence of processing. Finally, the dynamic thermal mechanical analysis results indicated that, with the addition of MAH, the compatibility between TPS and LLDPE in the blends was substantially improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 686–695, 2004