Ionomer compatibilised PA6/EVA blends: mechanical properties and morphological characterisation

The compatibilisation of PA6/EVA blends with the addition of an ionomer on the mechanical properties and morphology were studied as a function of ionomer concentration with the primary aim of enhancing the impact strength of PA6 by EVA. The level of EVA was kept at 20%, which formed the dispersed phase, and the ionomer content was varied from 0 to 1.6 wt%. It was found that notched Izod impact strength of PA6/EVA/ionomer blends increased with the incorporation of ionomer to about three times of the value for uncompatibilised PA6/EVA blends. Further, it was observed that on incorporation of the ionomer the tensile strength also increased significantly. Analysis of the tensile data using predictive theories indicated an enhanced interaction of the dispersed phase and the matrix. SEM studies of cryogenically fractured surfaces indicated a decrease in dispersed phase domain size with the addition of the ionomer, while the impact fractured surfaces of PA6/EVA blends indicated extensive deformation with the formation of rumples indicating increased interfacial adhesion as compared to PA6/EVA blends. An attempt has been made to evaluate the compatibilising efficiency of ionomer in PA6/EVA blends.     

Rheological and mechanical properties of compatibilized polystyrene/ethylene vinyl acetate blends

In this study, a blend of polystyrene (PS)/ethylene vinyl acetate (EVA) (PS/EVA, 90 : 10 wt %) was compatibilized with three different block copolymers, in which their end blocks were compatible with either styrene or EVA. The compatibilized blends with different compositions were prepared using a twin‐screw extruder and injection molded into the required test specimens. Mechanical properties of the blends, such as tensile properties and Charpy impact strength, morphology of tensile fractured surfaces, rheological properties, and thermal properties, were investigated. The results show that the interaction between the dispersed and continuous phase can be improved by the addition of a compatibilizer. Appreciable improvement in the impact strength of the blend with 15 wt % of compatibilizer C (polystyrene‐block‐polybutadiene) was observed. Its mechanical properties are comparable to those of the commercial high‐impact polystyrene, STYRON 470. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2071–2082, 2004     

Reactively compatibilised polyamide6/ethylene-co-vinyl acetate blends: mechanical properties and morphology

Mechanical properties and morphological studies of compatibilised blends of PA6/EVA-g-MA and PA6/EVA/EVA-g-MA were studied as functions of maleic anhydride content (MA) and dispersed phase (EVA-g-MA) concentrations, respectively at blending composition of 20 wt% dispersed phase (EVA-g-MA or combination of EVA and EVA-g-MA). The maleic anhydride (MA) was varied from 1 to 6 wt% in the PA6/EVA-g-MA blend, whereas MA concentration was fixed at 2 wt% in the ternary compositions with varying level of EVA-g-MA. ATR-IR spectroscopy revealed the formation of in situ copolymer during reactive compatibilisation of PA6 and EVA-g-MA. It was found that notched Izod impact strength of PA6/EVA-g-MA blends increased significantly with MA content in EVA-g-MA. The brittle to tough transition temperature of reactively compatibilised blends was found to be at 23 °C. The impact fractured surface topology reveals extensive deformation in presence of EVA-g-MA whereas; uncompatibilised PA6/EVA blend shows dislodging of EVA domains from the matrix. Tensile strength of the PA6/EVA-g-MA blends increased significantly as compared to PA6/EVA blends. Analysis of the tensile data using predictive theories showed an enhanced interaction of the dispersed phase and the matrix. It is observed from the phase morphological analysis that the average domain size of the PA6/EVA-g-MA blends is found to decrease gradually with increase in MA content of EVA-g-MA. A similar decrease is also found to observe in PA6/EVA/EVA-g-MA blends with increase in EVA-g-MA content, which suggest the coalescence process is slower in presence of EVA-g-MA. An attempt has been made to correlate between impact strength and morphological parameters with regard to the compatibilised system over the uncompatibilised system.     

Effect of the elastomer type on the microstructure and mechanical properties of polypropylene

In this study, the effects of the elastomer type—ethylene–propylene–diene monomer (EPDM), three kinds of ethylene vinyl acetate (EVA 9, EVA 18, and EVA 28, where the number is the vinyl acetate concentration), and styrene–butadiene–styrene—and content on the microstructure and mechanical and thermal properties of isotactic polypropylene (i‐PP) blends were investigated. Five different elastomer concentrations (3, 6, 9, 12, and 15 wt %) were added to i‐PP to produce polypropylene/elastomer blends. The yield and tensile strengths, elastic modulus, impact strength, hardness, melt flow index (MFI), and structural properties of the blends were investigated. The tensile and yield strengths, elastic modulus, and hardness decreased gradually, whereas the impact strength and MFI increased as the elastomer content increased. As a result, with respect to the impact strength, the most effective elastomers were EPDM with 15 wt % and EVA 28 with 15 wt % for higher impact strength values. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1445–1450, 2005     

PA6／HDPE／EVA三元共混改性的研究

研究了PA6/HDPE、PA6/HDPE/EVA共混物的密度、热性能和力学性能。PA6/HDPE/EVA三元共混物的力学性能比PA6/HDPE二元共混物有明显提高。对于拉伸强度,EVA的最佳含量在2～4份。冲击强度随EVA含量的增加而提高,EVA的含量小于5份时,对共混物的硬度几乎没有影响。     

Morphology and properties of PBT/nylon 6/EVA‐g‐MAH ternary blends prepared by reactive extrusion

Morphology and properties of poly(butylene terephthalate) (PBT)/nylon 6 (PA6)/EVA‐g‐MAH ternary blends were investigated. The blends were prepared in a corotating, intermeshing, twin‐screw extruder. The incorporation of maleic anhyride (MAH) grafted onto ethylene‐vinyl acetate copolymer (EVA) (EVA‐g‐MAH) in the PBT/PA6 binary blends decreased the tensile and flexural strength but increased the impact strength, while the mechanical properties of the PBT/PA6 blends were decreased with increasing PA6 content regardless of the presence or absence of the EVA‐g‐MAH. The morphology studies of the ternary blends showed gross phase separation. The rheological properties of the ternary blends suggested that excessively high reactivity between amine end groups of PA6 and MAH grafted onto EVA makes the compatibility between PBT and PA6 worse, although EVA‐g‐MAH was expected to work as a compatibilizer for PBT/PA6 blends. The degree of reactivity between functional groups in PBT, PA6, and EVA‐g‐MAH was also examined by investigating the effect of blending sequence on the properties of the ternary blends.     

Properties of uncompatibilized and compatibilized poly(butylene terephthalate)–LLDPE blends

In this work, blends of poly(butylene terephthalate) (PBT) and linear low‐density polyethylene (LLDPE) were prepared. LLDPE was used as an impact modifier. Since the system was found to be incompatible, compatibilization was sought for by the addition of the following two types of functionalized polyethylene: ethylene vinylacetate copolymer (EVA) and maleic anhydride‐grafted EVA copolymer (EVA‐g‐MAH). The effects of the compatibilizers on the rheological and mechanical properties of the blends have been also quantitatively investigated. The impact strength of the PBT–LLDPE binary blends slightly increased at a lower concentration of LLDPE but increased remarkably above a concentration of 60 wt % of LLDPE. The morphology of the blends showed that the LLDPE particles had dispersed in the PBT matrix below 40 wt % of LLDPE, while, at 60 wt % of LLDPE, a co‐continuous morphology was obtained, which could explain the increase of the impact strength of the blend. Generally, the mechanical strength was decreased by adding LLDPE to PBT. Addition of EVA or EVA‐g‐MAH as a compatibilizer to PBT–LLDPE (70/30) blend considerably improved the impact strength of the blend without significantly sacrificing the tensile and the flexural strength. More improvement in those mechanical properties was observed in the case of the EVA‐g‐MAH system than for the EVA system. A larger viscosity increase was also observed in the case of the EVA‐g‐MAH than EVA. This may be due to interaction of the EVA‐g‐MAH with PBT. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 989–997, 1999     

Comparison Properties of Natural Rubber (SMR L)/Ethylene Vinyl Acetate (EVA) Copolymer Blends and Epoxidized Natural Rubber (ENR-50)/Ethylene Vinyl Acetate (EVA) Copolymer Blends

Mixing torque, morphology, tensile properties and swelling studies of natural rubber/ethylene vinyl acetate copolymer blends were studied. Two series of unvulcanized blends, natural rubber/ethylene vinyl acetate (SMRL/EVA) copolymer blend and epoxidized natural rubber (50% epoxidation)/ethylene vinyl acetate (ENR-50/EVA) copolymer blend were prepared. Blends were prepared using a laboratory internal mixer, Haake Rheomix polydrive with rotor speed of 50 rpm at 120°C. Results indicated that mixing torque value and stabilization torque value in ENR-50 blends are lower than SMRL blends. The process efficiency of ENR-50/EVA blends is better due to less viscous nature of the blend compared to SMRL/EVA blends as indicated in stabilization torque graph. Tensile properties like tensile strength, M100 (modulus at 100% elongation) and E _b (elongation at break) increase with increasing EVA fraction in the blend. At the similar blend composition, ENR-50 blend shows better tensile properties than SMRL blends. In oil resistance test, swelling percentage increased with immersion time and rubber composition. At a similar immersion time, ENR-50 blends exhibit better oil resistance compared to SMRL blends. Scanning electron microscopy (SEM) of tensile fractured surface indicated that EVA/ENR-50 blends need higher energy to cause catastrophic failure compared to EVA/SMRL blends. In etched cryogenically fractured surface, size and distribution of holes due to extraction of rubber phase by methyl ethyl ketone (MEK) were studied and holes became bigger as rubber composition increased due to coalescence of rubber particle.     

热塑性淀粉增韧改性聚酰胺6的研究

将甘油增塑玉米淀粉制得的热塑性淀粉（TPS）与聚酰胺6（PA6）进行熔融共混,制备PA6/TPS共混物,研究不同含量的甘油和TPS对PA6/TPS共混物性能的影响,并探讨TPS增韧PA6的机理。采用万能试验机、溶体流动速率仪和扫描电子显微镜对改性PA6进行表征。结果表明,加入TPS后,共混物的冲击强度和拉伸模量有所提高,而拉伸强度和熔体流动速率略有下降,表明TPS对PA6起到了有机刚性粒子增韧的作用;TPS对PA6的增韧机理主要是界面脱黏、空化作用;甘油含量对TPS改性PA6的韧性影响显著,甘油含量为25 %的TPS添加量为25 %时,其增韧效果最好,冲击强度比PA6提高了63 %。     

POM／COPA二元及POM／COPA／EVA三元共混物的研究

研究了聚甲醛供聚酰胺（POM/COPA）二元及聚甲醛／共聚酰胺／乙烯-醋酸乙烯酯共聚物（POM／COPA／EVA）三元共混物，探讨了COPA、EVA用量对共混体系性能的影响。结果表明，C1DPA的加入使共混物的熔融温度（Tm）增大；当COPA含量为4％（质量分数，下同）时，00PA能够较均匀地分散于POM基体中，共混物缺口冲击强度出现最大值，比纯聚甲醛提高了约63．3％，而拉伸强度变化不大，POM／COPA共混物具有较理想的综合力学性能。EVA的加入使共混物缺口冲击强度和拉伸强度均呈下降趋势。     

Influence of PP content on mechanical properties,water absorption,and morphology in PA6/PP blend

PA6/polypropylene (PP) blends are investigated for obtaining balanced strength and toughness. The focus of this study is to understand the effect of PP content on mechanical property, water absorption, impact strength, thermal behavior, and morphology of PP in the absence and presence of PP-g-maleic anhydride compatibilizer. In comparison to pure PA6, all blends have higher impact strength with 161 and 124% increase at 5 wt % PP content in uncompatibilized and compatibilized blends (UB and CB), respectively. Morphology of impact fractured samples shows brittle fracture in the case of CB. scanning electron microscope of cryogenically fractured samples show decrease in domain size and change in shape from ellipsoid to spherical, from UB to CB. Then, 75% reduction in water absorption is observed for 50 wt % PP content UB. Postwater absorption yield strength (YS) remains constant above 10 wt % PP in both UB and CB and decrease in YS is less at higher PP content in CB. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47690.     

Mechanical properties of polystyrene/polyamide 6 blends compatibilized with the ionomer poly(styrene‐co‐sodium acrylate)

The compatibilizing effect of the ionomer, poly(styrene‐co‐sodium acrylate) (PSSAc), on immiscible blends of polystyrene (PS)/polyamide 6 (PA6) was studied by mechanical tests and scanning electron microscopy. The PSSAc acts as an effective compatibilizer because both the deformation at break (%) obtained by tensile stress–strain tests and the impact rupture energy are larger in blends containing small amounts of PSSAc. The morphologies of the fractured surfaces produced by tensile stress–strain tests of blends with or without the ionomer confirm that PSSAc increases the interfacial adhesion between PS and PA6 phases. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2545–2551, 2004     

Toughening and compatibilization of polypropylene/polyamide‐6 blends with a maleated–grafted ethylene‐co‐vinyl acetate

In this article, maleated–grafted ethylene‐co‐vinyl acetate (EVA‐g‐MA) was used as the interfacial modifier for polypropylene/polyamide‐6 (PP/PA6) blends, and effects of its concentration on the mechanical properties and the morphology of blends were investigated. It was found that the addition of EVA‐g‐MA improved the compatibility between PP and PA6 and resulted in a finer dispersion of dispersed PA6 phase. In comparison with uncompatibilized PP/PA6 blend, a significant reduction in the size of dispersed PA6 domain was observed. Toluene‐etched micrographs confirmed the formation of interfacial copolymers. Mechanical measurement revealed that the addition of EVA‐g‐MA markedly improved the impact toughness of PP/PA6 blend. Fractograph micrographs revealed that matrix shear yielding began to occur when EVA‐g‐MA concentration was increased upto 18 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99:3300–3307, 2006     

Effect of reactive compatibilisation on the phase morphology and tensile properties of PA12/PP blends

Both uncompatibilized and compatibilized blends based on polyamide 12 (PA12) and isotactic polypropylene (PP) were prepared in a Brabender Plastograph®. The compatibiliser used was maleic anhydride functionalized polypropylene (PP‐g‐MA). Phase morphology of the blends was inspected in scanning electron microscope (SEM) on cryogenically fractured etched surfaces of the specimens. PA12/PP blends possessed a nonuniform and unstable morphology owing to the incompatibility between their constituents. Addition of compatibiliser improved the interfacial characteristics of the blends by retarding the rate of coalescence. So, the phase morphology became more fine, uniform, and stable. Tensile properties of both uncompatibilized and compatibilized blends were measured as a function of blend composition and compatibiliser concentration. Uncompatibilized blends displayed inferior mechanical properties to compatibilized ones; especially for those containing 40–60 wt % of PP. Reactive compatibilisation of blends was found to be efficient and improved the tensile strength of the blends considerably. Addition of PP‐g‐MA improved the interfacial adhesion, decreased the interfacial tension, and thereby, enhanced the tensile strength by 85%. Finally, various models were adopted to describe the tensile strength of the blends. The experimental data exhibited a reasonably good fit with Nielsen's first power law model. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Modification of lignin–polyethylene blends with high lignin content using ethylene–vinylacetate copolymer as modifier

Blending of polyethylene with lignin in concentrations > 20 wt % yielded blends with relatively low mechanical properties. A new method, based on modification of polyethylene with ethylene–vinylacetate (EVA) copolymer, was developed for the preparation of polyethylene blends containing about 30 wt % lignin with acceptable strength properties. The addition of 10 wt % EVA caused an increase of tensile strength about twice and elongation at break about 13 times compared to those of the corresponding nonmodified samples. The optimization of lignin–polyethylene–EVA blend composition was based on a regression equation, which was obtained as output from an experimental design. The prepared composite material with 33.6 wt % lignin showed acceptable processing and mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1855–1860, 2004     

Failure analysis of rubber toughened epoxy resin

Failure of the blends of epoxy cresol novolac resin (ECN) with varied proportions of carboxy terminated polybutadiene (CTPB) liquid functional rubber was studied. Addition of CTPB improves toughness as reflected in the improvement of tensile, flexural, and impact properties. However, 10 wt % of CTPB was the optimum concentration beyond which a rapid fall of properties, in all cases, was observed. Surface topography of the fractured surfaces, studied by scanning electron microscopy and atomic force microscopy, revealed marked changes in the phase morphology due to addition of rubber and also accounted for the variation of the strength properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 861–868, 2003     

树形分子对PA11/PA6共混物性能的影响

在PA11／PA6共混物中添加4．0代树形分子,提高了共混物的性能,研究了不同树形分子含量对共混物力学性能、耐热性和流动性的影响。结果表明,在PA11／PA6中添加0．25％树形分子后,共混物的拉伸强度、断裂伸长率明显提高,缺口冲击强度和维卡软化温度略有增加,但流动性有所下降。     

Enhancement of the tensile retraction properties of a styrenic block copolymer by melt blending with PA6

Styrene–ethylene‐propylene–styrene triblock copolymer (SEPS), a thermoplastic elastomer (TPE) was blended with polyamide‐6 (PA6) in an attempt to improve the retraction properties of the TPE. A maximum loading of 30 wt % of polyamide was incorporated into SEPS using twin‐screw compounding. Various reactive compatibilisers were also incorporated at a maximum loading of 10 wt %. The blends were evaluated in terms of their tensile, dynamic mechanical, and rheological behavior. Design of experiments (DOE) was used to study the effect of blending variables on the tensile properties of the blends. Complex interactions between these variables were identified using this approach. It was shown that by incorporating PA6 into SEPS, in conjunction with a compatibilizer, blends with superior retraction properties and increased tensile strength could be obtained. A mean hysteresis of 54.2 ± 0.7% was recorded for a blend containing 5 wt % PA6 and 4 wt % compatibilizer compared to 58.5 ± 0.5% for virgin SEPS. The tensile strength of this blend was almost 75% higher than virgin SEPS. Further evidence of the benefit of incorporating a reactive compatibilizer was the absence of a distinct polyamide relaxation in the dynamic mechanical thermograms for the compatibilized blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Morphology and mechanical properties of reactive compatibilized polystyrene/ethylene‐vinyl acetate‐vinyl alcohol blends

A reactive compatibilizer, styrene‐maleic anhydride (SMA) was used to compatibilize the blends of polystyrene (PS) and ethylene‐vinyl acetate‐vinyl alcohol (EVAOH), which was synthesized from ethylene‐vinyl acetate (EVA) using transesterification reaction. The compatibilized blends with different compositions were prepared using a twin‐screw extruder and injection molded into the required test specimens. Morphology of Charpy impact‐fractured surfaces, tensile, and impact properties of the blends were investigated. Fourier‐transform infrared spectroscopy (FTIR) was also applied for specific samples to elucidate the presence of the functional groups reaction necessary for reactive compatibilization. The results of the ternary PS/EVAOH/SMA blends illustrate that the addition of SMA as a compatibilizer slightly reduce the elongation at break. From the impact‐fractured surfaces of the blends, it is evident that the morphology developed sizable pores when SMA was added into the blends. This might be attributed to the residual octanol‐1, produced from the synthesis of EVAOH, as there is a possibility of a reaction between hydroxyl groups in the octanol‐1 and the anhydride groups in the SMA. This disrupted the stability of the morphology and resulted in the decrease in the elongation, and hence, the tensile toughness. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 209–217, 2002     

Application of styrene‐acrylonitrile random copolymer–polyarylate block copolymer as reactive compatibilizer for polyamide and acrylonitrile‐butadiene‐styrene blends

Styrene‐acrylonitrile random copolymer (SAN) and polyarylate (PAr) block copolymer were applied as a reactive compatibilizer for polyamide‐6 (PA‐6)/acrylonitrile‐butadiene‐styrene (ABS) copolymer blends. The SAN–PAr block copolymer was found to be effective for compatibilization of PA‐6/ABS blends. With the addition of 3.0–5.0 wt % SAN–PAr block copolymer, the ABS‐rich phase could be reduced to a smaller size than 1.0 μm in the 70/30 and 50/50 PA‐6/ABS blends, although it was several microns in the uncompatibilized blends. As a result, for the blends compatibilized with 3–5 wt % block copolymer the impact energy absorption reached the super toughness region in the 70/30 and 50/50 PA‐6/ABS compositions. The compatibilization mechanism of PA‐6/ABS by the SAN–PAr block copolymer was investigated by tetrahydrofuran extraction of the SAN–PAr block copolymer/PA‐6 blends and the model reactions between the block copolymer and low molecular weight compounds. The results of these experiments indicated that the SAN–PAr block copolymer reacted with the PA‐6 during the melt mixing process via an in situ transreaction between the ester units in the PAr chain and the terminal amine in the PA‐6. As a result, SAN–PAr/PA‐6 block copolymers were generated during the melt mixing process. The SAN–PAr block copolymer was supposed to compatibilize the PA‐6 and ABS blend by anchoring the PAr/PA‐6 and SAN chains to the PA‐6 and ABS phases, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2300–2313, 2002