Mechanical properties and morphology of the modified HDPE/starch reactive blend

We investigated the effect of reactive blending on the mechanical properties and morphology of high‐density polyethylene (HDPE)/plasticized starch blends. HDPE was chemically modified to enhance the compatibility with the plasticized starch. The modified HDPE, HDPE‐g‐glycidyl methacrylate (GMA), was synthesized by melt reaction of HDPE in the presence of dicumyl peroxide (DCP). A finer dispersion of starch in the HDPE matrix was achieved compared to that in the unmodified HDPE. The amount of GMA groups in the modified HDPE enhanced the miscibility of HDPE/starch blends. We also observed that the amount of glycerin improves the mechanical properties of blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3313–3320, 2001     

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     

Compatibilization of high‐impact polystyrene/high‐density polyethylene blends by styrene/ethylene–butylene/styrene block copolymer

Compatibilization of polymer blends of high‐impact polystyrene (HIPS) and high‐density polyethylene (HDPE) blend by styrene/ethylene–butylene/styrene (SEBS) was elucidated. Polymer blends containing many ratios of HIPS and HDPE with various concentrations of SEBS were prepared. The Izod impact strength and elongation at break of the blends increased with increases in SEBS content. They increased markedly when the HDPE content was higher than 50 wt %. Tensile strength of blends increased when the SEBS concentration was not higher than 5 pphr. Whenever the SEBS loading was higher than 5 pphr, the tensile strength decreased and a greater decrease was found in blends in which the HDPE concentration was more than 50 wt %. The log additivity rule model was applied to these blends, which showed that the blends containing the HIPS‐rich phase gave higher compatibility at the higher shear rates. Surprisingly, the blends containing the HDPE‐rich phase yielded greater compatibility at the lower shear rates. Morphology observations of the blends indicated better compatibility of the blends with increasing SEBS concentration. The relaxation time (T₂) values from the pulsed NMR measurements revealed that both polymer blends became more compatible when the SEBS concentration was increased. When integrating all the investigations of compatibility compared with the mechanical properties, it is possible to conclude that SEBS promotes a certain level of compatibilization for several ratios of HIPS/HDPE blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 742–755, 2004     

Use of poly(ethylene‐co‐vinyl alcohol) as compatibilizer in LDPE/thermoplastic tapioca starch blends

Poly(ethylene‐co‐vinyl alcohol) (EVOH) was used as a compatibilizer to make blends of low‐density polyethylene (LDPE) and plasticized starch (TS). The tensile properties and impact strength were measured and compared with those of neat LDPE. The morphology of the blend specimens, both fractured and unfractured, was observed by scanning electron microscopy. Comparison of the properties showed that the impact strength of the blend improves significantly by the addition of a compatibilizer even with a high TS loading of 40 and 50% (by weight). A high elongation at break almost matching that of neat polyethylene was also obtained. The blend morphology of the etched specimens revealed fine dispersion of the starch in the polyethylene matrix, while the fracture surface morphology clearly indicate that the failure of compatibilized blends occurs mainly by the ductile mode. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3126–3134, 2002     

Study of compatibilization of HDPE–PET blends by adding grafted or statistical copolymers

The reactive compatibilization of blends of HDPE–PET [high‐density polyethylene–poly(ethylene terephthalate)] was investigated in this study. The compatibilizers used were two grafted copolymers prepared by reactive extrusion containing 1.20–2.30 wt % GMA such as HDPE‐g‐GMA and one statistical copolymer containing 1 wt % GMA such as Lotader AX8920. HDPE was successfully functionalized using a melt free‐radical grafting technique. Grafting was initiated in two ways: adding an initiator in the polymer–monomer mixture or activation by ozone of polymer. Ozonization of HDPE by the introduction of a peroxide lead to a better grafting yield and to better grafting efficiency of the samples. The effects of the three compatibilizers were evaluated by studying the morphology and the thermal and mechanical properties of HDPE–PET (70/30 wt %) blends. Significant improvements were observed, especially in morphology, elongation at break, and Charpy impact strength of the compatibilized blends. A more pronounced compatibilizing effect was obtained with the statistical copolymer, for which the elongation at break and the impact strength were increased by 100%, while the uncompatibilized blends showed a 60% decrease in the Young's modulus and the strength at break. We also were able to show that the grafting yield increase of 1.20–2.30 wt % of GMA did not affect the properties of the blends because the grafted copolymers possess very similar chemical structures. However, compatibilization of blends with grafted copolymers is an interesting method, particularly for recycled blends, because the synthesis of these compatibilizers is easy and cheap in comparison to statistical copolymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2377–2386, 2001     

Influence of high density polyethylene‐g‐maleic anhydride on compatibility and properties of poly(butylene terephthalate)/high density polyethylene blends

Poly(butylene terephthalate)/high density polyethylene (PBT/HDPE) blends and PBT/HDPE‐grafted maleic anhydride (PBT/HDPE‐g‐MAH) blends were prepared by the reactive extrusion approach, and the effect of blend compositions on the morphologies and properties of PBT/HDPE blends and PBT/HDPE‐g‐MAH blends was studied in detail. The results showed that flexural strength, tensile strength, and notched impact strength of PBT/HDPE blends decreased with the addition of HDPE, and flexural strength and tensile strength of PBT/HDPE‐g‐MAH blends decreased, while the notched impact strength of PBT/HDPE‐g‐MAH increased with the addition of HDPE‐g‐MAH. Compared with PBT/HDPE blends, the dimension of the dispersed phase particles in PBT/HDPE‐g‐MAH blends was decreased and the interfacial adhesion was increased. On the other hand, the effects of HDPE and HDPE‐g‐MAH contents on the crystalline and the rheological properties of the blends were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6081–6087, 2006     

Wood‐thermoplastic composites from wood flour and high‐density polyethylene

High‐density polyethylene/wood flour (HDPE/WF) composites were prepared by a twin‐screw extruder. The effects of WF, silane coupling agents, polymer compatibilizers, and their content on the comprehensive properties of the WF/HDPE composites have been studied in detail, including the mechanical, thermal, and rheological properties and microstructure. The results showed that both silane coupling agents and polymer compatibilizers could improve the interfacial adhesion between WF and HDPE, and further improve the properties of WF/HDPE composites, especially with AX8900 as a compatibilizer giving higher impact strength, and with HDPE‐g‐MAH as a compatibilizer giving the best tensile and flexural properties. The resultant composite has higher strength (tensile strength = 51.03 MPa) and better heat deflection temperature (63.1°C). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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     

Interfacial modification of high density polyethylene/glass fiber reinforced and non reinforced polyamide 66 blends

High density polyethylene (HDPE) and polyamide (PA66) are well known to be incompatible. An ionomer (Surlyn) was added as a compatibilizer to HDPE and glass fiber reinforced (HDPE/GFRPA66) and non‐reinforced (HDPE/PA66) blends. Two compositions were considered: 25/75 wt % and 75/25 wt %, with an emphasis on the former formulation. The influence of the compatibilizer on the rheology, thermal properties, and the morphology, as well as mechanical properties of the blends, was investigated using melt flow index measurements, DSC, scanning electron microscopy (SEM), and impact strength. The ionomer was found to be more effective as a compatibilizer with HDPE as a minor phase compared to the case when HDPE becomes the major phase. The results indicated that the interfacial properties of the blends were improved, with a maximum appearing at a critical concentration of the ionomer (7.5 vol %). At this level of compatibilization, SEM analysis revealed better interfacial adhesion and a finer dispersion. MFI results revealed a probable reaction between the amine groups of PA66 and the acid functions of the ionomer. The mechanical properties support the above results and showed that the addition of 25 wt % HDPE did not affect the properties of PA66 much and the presence of glass fiber did not hinder the effect of the compatibilizer. Only 20% decrease in notched Izod impact strength of the blends is observed at 7.5 vol % ionomer content, suggesting that the addition of 25 wt % of HDPE to PA66 is not detrimental at this level of compatibilization. The emulsification curve was established and revealed that, in terms of impact properties, the finer the particle size, the higher the impact strength corresponding to 7.5 vol % ionomer content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1748–1760, 2005     

Preparation,morphology, and properties of multilamellar barrier materials based on blends of high‐density polyethylene and copolyester

The multilamellar barrier materials based on the blends of high‐density polyethylene (HDPE) and copolyester (PETG) were prepared via melt extrusion, and poly(ethylene‐co‐acrylic acid) (EAA) as a compatibilizer was incorporated into the blends. A systematic investigation was carried out, with regard to morphology and properties. Scanning electron microscopy observation displayed the laminar morphology for the blends with the whole compositions, and the thinner laminas of the PETG phase formed in the HDPE matrix by incorporating EAA into the blends. In addition, the number and the size of the laminas of the dispersed phases were also dependant on the die temperature and screw speed, respectively. Evaluation of the mechanical properties demonstrated that incorporation of the EAA resulted in an improvement of the mechanical properties. These behaviors are attributed mainly to better adhesion and compatibility between HDPE and PETG, which has been confirmed by thermal analysis and the rheological properties. On the basis of these premises, it is reasonable to suggest that the improved barrier properties of the ternary blends with increasing concentration of the EAA be attributed to both the increase in the number of the laminas of the PETG and the decrease in their thickness, which prohibits the organic solvent molecules from entering into and permeating through the amorphous regions of the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3791–3799, 2006     

Compatibilizing effect of starch‐grafted‐poly(L‐lactide) on the poly(ε‐caprolactone)/starch composites

The poly(ε‐caprolactone) (PCL)/starch blends were prepared with a coextruder by using the starch grafted PLLA copolymer (St‐g‐PLLA) as compatibilizers. The thermal, mechanical, thermo‐mechanical, and morphological characterizations were performed to show the better performance of these blends compared with the virgin PCL/starch blend without the compatibilizer. Interfacial adhesion between PCL matrix and starch dispersion phases dominated by the compatibilizing effects of the St‐g‐PLLA copolymers was significantly improved. Mechanical and other physical properties were correlated with the compatibilizing effect of the St‐g‐PLLA copolymer. With the addition of starch acted as rigid filler, the Young's modulus of the PCL/starch blends with or without compatibilizer all increased, and the strength and elongation were decreased compared with pure PCL. Whereas when St‐g‐PLLA added into the blend, starch and PCL, the properties of the blends were improved markedly. The 50/50 composite of PCL/starch compatibilized by 10% St‐g‐PLLA gave a tensile strength of 16.6 MPa and Young's modulus of 996 MPa, respectively, vs. 8.0 MPa and 597 MPa, respectively, for the simple 50/50 blend of PCL/starch. At the same time, the storage modulus of compatibilized blends improved to 2940 MPa. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Studies on high density polyethylene (HDPE) functionalized by ultraviolet irradiation and its application

The structure and properties of high density polyethylene (HDPE) functionalized by ultraviolet irradiation at different light intensities in air were studied by electron analysis, FTIR spectroscopy, contact angle with water, differential scanning calorimetry and mechanical properties measurement. The results show that oxygen‐containing groups such as C?O, C—O and C(?O)O were introduced onto the molecular chain of HDPE following irradiation, and the rate and efficiency of HDPE functionalization increased with enhancement of irradiation intensity. After irradiation, the melting temperature, contact angle with water and notched impact strength of HDPE decreased, the degree of crystallinity increased, and their variation amplitude increased with irradiation intensity. Compared with HDPE, the yield strength of HDPE irradiated at lower light intensity (32 W m^?2 and 45 W m^?2) increases monotonically with irradiation time, and the yield strength of HDPE irradiated at higher light intensity (78 W m^?2) increases up to 48 h and then decreased with further increase in irradiation time. The irradiated HDPE behaved as a compatibilizer in HDPE/polycarbonate (PC) blends, and the interface bonding between HDPE and PC was ameliorated. After adding 20 wt% HDPE irradiated at 78 W m^?2 irradiation intensity for 24 h to HDPE/PC blends, the tensile yield strength and notched Izod impact strength of the blend were increased from 26.3 MPa and 51 J m^?1 to 30.2 MPa and 158 J m^?1, respectively. Copyright © 2003 Society of Chemical Industry     

Blends of recycled polycarbonate and acrylonitrile–butadiene–styrene: comparing the effect of reactive compatibilizers on mechanical and morphological properties

Blends of recycled polycarbonate (PC) and acrylonitrile–butadiene–styrene (ABS) were prepared and some mechanical and morphological properties were investigated. To compatibilize these blends, ABS‐g‐(maleic anhydride) (ABS‐g‐MA) and (ethylene–vinyl acetate)‐g‐(maleic anhydride) (EVA‐g‐MA) with similar degree of grafting of 1.5% were used. To compare the effect of the type of compatibilizer on mechanical properties, blends were prepared using 3, 5 and 10 phr of each compatibilizer. A co‐rotating twin‐screw extruder was used for blending. The results showed that ABS‐g‐MA had no significant effect on the tensile strength of the blends while EVA‐g‐MA decreased the tensile strength, the maximum decrease being about 9.6% when using 10 phr of this compatibilizer. The results of notched Charpy impact strength tests showed that EVA‐g‐MA increased the impact strength of blends more than ABS‐g‐MA. The maximum value of this increase occurred when using 5 phr of each compatibilizer, it being about 54% for ABS‐g‐MA and 165% for EVA‐g‐MA. Scanning electron microscopy micrographs showed that the particle size of the dispersed phase was decreased in the continuous phase of PC by using the compatibilizers. Moreover, a blend without compatibilizer showed brittle behaviour while the blends containing compatibilizer showed ductile behaviour in fracture. © 2013 Society of Chemical Industry     

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     

PVC/HDPE共混材料的研制及性能研究

以氯乙烯-丙烯酸丁酯共聚物[P(V-B)]作为PVC和高密度聚乙烯(HDPE)的增容剂，研究讨论了共混物的相容性及其加工性能，并在此基础上研制了以P(V-B)为增容剂的PVC／HDPE共混材料，进而研究了共混材料的力学性能。结果表明：合适配比的共混体系具有良好的相容性、塑化效果和流动性能，明显改善了PVC的加工性能，并在拉伸强度、弯曲强度等具有较高保持率的前提下，显著地提高了材料的冲击性能。     

Morphology and mechanical properties of styrene–ethylene/butylene–styrene triblock copolymer/high‐density polyethylene composites

The morphology and mechanical properties of a styrene–ethylene/butylene–styrene triblock copolymer (SEBS) incorporated with high‐density polyethylene (HDPE) particles were investigated. The impact strength and tensile strength of the SEBS matrix obviously increased after the incorporation of the HDPE particles. The microstructure of the SEBS/HDPE blends was observed with scanning electron microscopy and polar optical microscopy, which illustrated that the SEBS/HDPE blends were phase‐separation systems. Dynamic mechanical thermal analysis was also employed to characterize the interaction between SEBS and HDPE. The relationship between the morphology and mechanical properties of the SEBS/HDPE blends was discussed, and the toughening mechanism of rigid organic particles was employed to explain the improvement in the mechanical properties of the SEBS/HDPE blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Low‐density polyethylene/plasticized tapioca starch blends with the low‐density polyethylene functionalized with maleate ester: Mechanical and thermal properties

In this study, the mechanical and thermal properties of low‐density polyethylene (LDPE)/thermoplastic tapioca starch blends were determined with LDPE‐g‐dibutyl maleate as the compatibilizer. Mechanical testing for the evaluation of the impact strength and tensile properties was carried our as per standard ASTM methods. Thermogravimetric analysis and differential scanning calorimetry were also used to assess the thermal degradation of the blends. Scanning electron micrographs were used to analyze fracture and blend morphologies. The results show significant improvement in the mechanical properties due to the addition of the compatibilizer, which effectively linked the two immiscible blend components. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1109–1120, 2006     

In situ compatibilization of HDPE/PET blends

The reactive compatibilization of immiscible polymers such as high‐density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) by interfacial grafting of maleic anhydride (MA) without initiator in the molten state was investigated in this study. Grafting reaction of MA onto HDPE was carried out in a Rheocord HAAKE mixer varying reaction parameters such as the temperature, the shear rate, and the time of reaction. Then, the purified copolymers were characterized by infrared spectrometry and the MA content of HDPE‐g‐MA copolymers was determined by volumetric titration. It has been shown that thermomechanical initiation is sufficient to reach grafting yield of 0.3 to 2.5 wt % of MA. We studied then the compatibilization of HDPE/PET blends by interfacial grafting of MA. The in situ interfacial reaction leads to the formation of HDPE‐g‐MA copolymer which acts as a compatibilizer in the blends. The foremost interest of this work is that it provides a simple way of compatibilization of immiscible blends of polyolefin and polyester in one transformation step without using free‐radical initiators. The mechanical properties of the blends are strongly improved by the addition of small quantities of MA. The SEM observations of the compatibilized blends show a deep modification of the structure (i.e., enhanced regularity in the nodule dispersion and better interfacial adhesion). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 874–880, 2001     

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     

Mechanical and dynamic mechanical properties of waste rubber powder/HDPE composite

Mechanical and dynamic mechanical properties of a waste rubber powder‐filled high‐density polyethylene (HDPE) composite are investigated. Rubber powder is surface‐modified with acrylamide (AAm) using ultraviolet. Rubber powder and HDPE are extruded using a single‐screw extruder and maleic anhydride‐grafted polypropylene is added as a compatibilizer to improve the adhesion between rubber powder and HDPE. The tensile stress and strain of AAm‐grafted rubber powder/compatibilizer/HDPE composites always exhibit higher values than those of unmodified rubber powder/HDPE composites. Surface modification of rubber powder is shown to decrease the magnitude of the tan δ of the HDPE composite. Higher values of the notched Izod impact strength of a surface‐modified rubber‐filled composite is observed compared to those of unmodified rubber‐filled composite. Experimental results show that acryl amide‐grafted rubber powder reacts with maleic anhydride and it results in improved mechanical properties of the HDPE composite. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2595–2602, 2000