Crystallization Kinetics and Melting Behavior of PA1010/Ether-based TPU Blends

Polyamide 1010(PA1010)/thermoplastic poly(ether urethane) elastomer(ether-based TPU) blends were prepared via melt extrusion. The crystallization kinetics and melting behavior of PA1010/ether-based TPU blends were systematically investigated using differential scanning calorimetry. The crystallization kinetics results show that the addition of ether-based TPU hinders the crystallization of PA1010, and the hindrance effect increases with the increase of the concentration of ether-based TPU. Both pure PA1010 and PA1010/ether-based TPU blends exhibit double melting peaks in the process of nonisothermal crystallization. The double melting peaks change differently with the variation of cooling rate and blend composition. The cooling rate only influences the lower melting peak; however, the blend composition influences not only the lower melting peak but also the higher melting peak. The reason for the phenomenon must be the interaction between the two compositions.     

刚性粒子增韧尼龙1010体系的研究

采用扫描电镜和动态力学等研究了在磺化聚苯乙烯（ＨＳＰＳ）作用下，尼龙１０１０（ＰＡ１０１０）／聚苯乙烯（ＰＳ）共混物的形态及相容性。结果表明，ＨＳＰＳ的加入显著改善了ＰＳ与ＰＡ１０１０的相容性，加强了界面粘结，使共混物缺口冲击明显提高，实现了ＰＳ增韧ＰＡ１０１０的目标。偏光显微竟结盟表明，ＨＳＰＳ的加入对共混物中ＰＡ１０１０的结晶形态有明显影响，使ＰＡ１０１０球晶细化且不完善。     

Phase morphology development in PP/PA6 blends induced by a maleated thermoplastic elastomer

The effects of maleated thermoplastic elastomer (TPEg) on morphological development of polypropylene (PP)/polyamide 6 (PA6) blends with a fixed PA6 content (30 wt %) were investigated. For purpose of comparison, nonmaleated thermoplastic elastomer (TPE) was also added to the above binary blends. A comparative study of FTIR spectroscopy in above both ternary blends confirmed the formation of in situ graft copolymer in the PP/PA6/TPEg blend. Dynamic mechanical analysis (DMA) indicated that un‐like TPE, the incorporation of TPEg remarkably affected both intensity and position of loss peaks of blend components. Scanning electron microscopy (SEM) demonstrated that PP/PA6/TPE blends still exhibited poor interfacial adhesion between the dispersed phase and matrix. However, the use of TPEg induced a finer dispersion and promoted interfacial adhesion. Transmission electron microscopy (TEM) for PP/PA6/TPEg blends showed that a core‐shell structure consisting of PA6 particles encapsulated by an interlayer was formed in PP matrix. With the concentration of TPEg increasing, the dispersed core‐shell particles morphology was found to transform from discrete acorn‐type particles to agglomerate with increasing degree of encapsulation. The modified Harkin's equation was applied to illustrate the evolution of morphology with TPEg concentration. “Droplet‐sandwiched experiments” further confirmed the encapsulation morphology in PP/PA6/TPEg blends. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1050–1061, 2006     

Linear viscoelastic properties of high‐density polyethylene/polyamide‐6 blends extruded in the presence of ultrasonic oscillations

Blends of high‐density polyethylene (HDPE) and polyamide‐6 (PA6) were produced by ultrasonic extrusion. Ultrasonic irradiation leads to degradation of polymers and in situ compatibilization of blends as confirmed by variations in linear viscoelastic properties. The results showed that the effect of ultrasonic irradiation on dynamic rheological properties depends on the composition and experimental temperature. At the same time, the relationship between storage modulus and loss modulus indicated the effect of ultrasonic irradiation on compatibility of HDPE/PA6 blends. Based on an emulsion model, the interfacial tension between the matrix and the dispersed phase was predicted. The data obtained showed that ultrasonic irradiation can decrease the interfacial tension and then enhance the compatibility of HDPE/PA6 blends. This finding was consistent with our previous work. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1260–1269, 2005     

Impact fracture toughness of polyamide‐6/montmorillonite nanocomposites toughened with a maleated styrene/ethylene butylene/styrene elastomer

Polyamide‐6 (PA6)/montmorillonite (MMT) nanocomposites toughened with maleated styrene/ethylene butylene/styrene (SEBS‐g‐MA) were prepared via melt compounding. Before melt intercalation, MMT was treated with an organic surfactant agent. Tensile and impact tests revealed that the PA6/4% MMT nanocomposite fractured in a brittle mode. The effects of SEBS‐g‐MA addition on the static tensile and impact properties of PA6/4% MMT were investigated. The results showed that the SEBS‐g‐MA addition improved the tensile ductility and impact strength of the PA6/4% MMT nanocomposite at the expenses of its tensile strength and stiffness. Accordingly, elastomer toughening represents an attractive route to novel characteristics for brittle clay‐reinforced polymer nanocomposites. The essential work of fracture (EWF) approach under impact drop‐weight conditions was used to evaluate the impact fracture toughness of nanocomposites toughened with an elastomer. Impact EWF measurements indicated that the SEBS‐g‐MA addition increased the fracture toughness of the PA6/4% MMT nanocomposite. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 585–595, 2005     

Annealing induced microstructure and fracture resistance changes in isotactic polypropylene/ethylene‐octene copolymer blends with and without β‐phase nucleating agent

Previous work showed that annealing induced the great improvement of fracture resistance of β‐iPP, relating to the decreased number of chain segments in the amorphous region. To further prove the rationality of this observation, in this work, the ethylene‐octene copolymer (POE) toughened isotactic polypropylene (iPP) blends with or without β‐phase nucleating agent (β‐NA) were adopted and the changes of microstructure and fracture resistance during the annealing process were further investigated comparatively. The results showed that, whether for the α‐phase crystalline structure (non‐nucleated) or for the β‐phase crystalline structure (β‐NA nucleated) in iPP matrix, annealing can induce the dramatic improvement of fracture resistance at a certain annealing temperature (120–140 °C for β‐NA nucleated blends whereas 120–150 °C for non‐nucleated blends). Especially, non‐nucleated blends exhibit more apparent variations in fracture resistance compared with β‐NA nucleated blends during the annealing process. The phase morphology of elastomer, supermolecular structure of matrix, the crystalline structure including the degree of crystallinity and the relative content of β‐phase, and the relaxation of chain segments were investigated to explore the toughening mechanism of the samples after being annealed. It was proposed that, even if the content of elastomer is very few, the excellent fracture resistance can be easily achieved through adjusting the numbers of chain segments in the amorphous phase by annealing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Effects of nucleating agents on microstructure and fracture toughness of poly(propylene)/ethylene‐propylene‐diene terpolymer blends

The effects of nucleating agents (NAs) on fracture toughness of injection‐molded isotactic poly(propylene)/ethylene‐propylene‐diene terpolymer (PP/EPDM) were studied in this work. Compared with PP/EPDM blends without any NA, PP/EPDM/NA blends show very small and homogeneous PP spherulites. As we expected, PP/EPDM blends nucleated with β‐phase NA aryl amides compound (TMB‐5) present not only a significant enhancement in toughness but also a promotion of brittle‐ductile transition. However, the addition of α‐phase NA 1,3:2,4‐bis(3,4‐dimethylbenzylidene) sorbitol (DMDBS) has no apparent effect on the toughness of the blends. The impact‐fractured surface morphologies of such samples were analyzed via scanning electronic microscope (SEM). More detail work about the toughening mechanisms of elastomer and NA based on elastomer particles size and matrix crystal structures were carried out. Our results suggest that, besides the crystal structures of matrix, the elastomer particles size and size distribution plays an important role in controlling the toughening effect of nucleated PP/elastomer blends. The smaller the elastomer particles size and lower the polydispersity, the more apparent the synergistic toughening effect of NA and elastomer is. This investigation provides a fresh insight into the understanding of toughening mechanism of elastomers in PP blends and facilitates to the design of super toughened PP materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 46–59, 2009     

Polypropylene/montmorillonite nanocomposites toughened with SEBS‐g‐MA: Structure–property relationship

Polypropylene (PP)/organo‐montmorillonite (Org‐MMT) nanocomposites toughened with maleated styrene‐ethylene‐butylene‐styrene (SEBS‐g‐MA) were prepared via melt compounding. The structure, mechanical properties, and dynamic mechanical properties of PP/SEBS‐g‐MA blends and their nanocomposites were investigated by X‐ray diffraction (XRD), polarizing optical microscopy (POM), tensile, and impact tests. XRD traces showed that Org‐MMT promoted the formation of β‐phase PP. The degree of crystallinity of PP/SEBS‐g‐MA blends and their nanocomposites were determined from the wide angle X‐ray diffraction via profile fitting method. POM experiments revealed that Org‐MMT particles served as nucleating sites, resulting in a decrease of the spherulite size. The essential work of fracture approach was used to evaluate the tensile fracture toughness of the nanocomposites toughened with elastomer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3112–3126, 2005     

Effect of EVM/EVA‐g‐MAH ratio on the structure and properties of nylon 1010 blends

The nylon 1010/ethylene‐vinyl acetate rubber (EVM)/maleated ethylene‐vinyl acetate copolymers (EVA‐g‐MAH) ternary blends were prepared. The effect of EVM/EVA‐g‐MAH ratio on the toughness of blends was examined. A super tough nylon 1010 blends were obtained by the incorporation of both EVM and EVA‐g‐MAH. Impact essential work of fracture (EWF) model was used to characterize the fracture behavior of the blends. The nylon/EVM/EVA‐g‐MAH (80/15/5) blend had the highest total fracture energy at a given ligament length (5 mm) and the highest dissipative energy density among all the studied blends. Scanning electron microscopy images showed the EVM and EVA‐g‐MAH existed as spherical particles in nylon 1010 matrix and their size decreased gradually with increasing EVA‐g‐MAH content. Large plastic deformation was observed on the impact fracture surface of the nylon/EVM/EVA‐g‐MAH (80/15/5) blend and related to its high impact strength. Then with increasing EVA‐g‐MAH proportion, the matrix shear yielding of nylon/EVM/EVA‐g‐MAH blends became less obvious. EVM and EVA‐g‐MAH greatly increased the apparent viscosity of nylon 1010, especially at low shear rates. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 877–887, 2009     

The effect of polyethylene addition on the morphology of polystyrene/polyamide blends

The effect of a small admixture of high‐density polyethylene (HDPE) with a high or low viscosity to polystyrene/polyamide (PS/PA) blends of various compositions was studied. PS/PA blends with composition near 50/50 form sheet‐like or fiber‐like morphology at mixing that passes to the cocontinuous structure during compression molding. Ternary PS/PA/HDPE blends with PS/PA ratio about 50/50 show similar behavior. Generally, neither continuity nor shape of PS and PA phases was changed qualitatively by the addition of a small amount of HDPE. In agreement with existing rules for ternary blends, HDPE particles prefer a contact with PS phase to PA phase. On the other hand, none of these rules explains why a number of small HDPE subinclusions were dispersed into PS particles instead of HDPE‐PS core‐shell structure with a lower Gibbs free energy. Quantitative evaluation of the size of PA particles in blends with PS matrix showed that the previously proposed rule stating, that the addition of a small amount of a third immiscible component leads to a strong decrease in the size of dispersed particles, was not valid for the blends studied in this work. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2158–2170, 2009     

Room temperature deformable shape memory composite with fine‐tuned crystallization induced via nanoclay particles

It is known that particular types of semi‐crystalline/elastomer polymer blends exhibit shape memory effects (SME) due to the dispersion of two immiscible phases. In this study, the crystal structure of polylactic acid (PLA)/ thermoplastic polyurethane (TPU) based shape memory polymer (SMP) is altered by incorporating small amounts of montmorillonite (MMT) nanoclay. The results indicate the incorporation of MMT can improve the compatibility of the two different polymers. Moreover, the presence of MMT affects the total crystallinity of the SMP and improves mechanical properties. Lastly, uniaxial stretching deformation can be applied to the SMP at room temperature conditions while maintaining its shape memory properties. With 1 wt % MMT particles, the recovery ratio (Rr) was nearly 95%, which indicated a strong recovery effect. The shape‐fixing ratio (Rf) remained above 95% for all composites due to plastic deformation applied at room temperature. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1197–1206     

Use of maleic anhydride compatibilization to improve toughness and other properties of polylactide blended with thermoplastic elastomers

Polylactide (PLA) being a very brittle biopolymer could be toughened by blending with thermoplastic elastomers such as thermoplastic polyurethane elastomer (TPU) and thermoplastic polyester elastomer (TPE); unfortunately, these blends are immiscible forming round domains in the PLA matrix. Therefore, the purpose of this study was to investigate the effects of using maleic anhydride (MA) compatibilization on the toughness and other properties of PLA blended with TPU and TPE. MA grafting on the PLA backbone (PLA‐g‐MA) was prepared separately by reactive extrusion and added during melt blending of PLA/thermoplastic elastomers. IR spectroscopy revealed that MA graft might interact with the functional groups present in the hard segments of TPU and TPE domains via primary chemical reactions, so that higher level of compatibilization could be obtained. SEM studies indicated that PLA‐g‐MA compatibilization also decreased the size of elastomeric domains leading to higher level of surface area for more interfacial interactions. Toughness tests revealed that Charpy impact toughness and fracture toughness (K_IC and G_IC) of inherently brittle PLA increased enormously when the blends were compatibilized with PLA‐g‐MA. For instance, G_IC fracture toughness of PLA increased as much as 166%. It was also observed that PLA‐g‐MA compatibilization resulted in no detrimental effects on the other mechanical and thermal properties of PLA blends. Copyright © 2014 John Wiley & Sons, Ltd.     

显微镜图像分析研究聚丙烯/尼龙1010共混物相结构及其性能

用扫描电子显微镜图像分析研究了聚丙烯/聚酰胺1010共混物及其部分相容体系的相形态结构,计算了表征相结构和尺寸的结构参数,如分散相的平均直径、平均弦长和分散相的质心相关距等.并分别讨论了聚丙烯/聚酰胺1010共混物及其部分相容体系的相形态以及其结构参数与共混物组成的关系.测定了聚合物及其共混物体系的力学性能,讨论了共混物组成与力学性能的关系.聚丙烯/聚酰胺1010共混物的拉伸模量与组成的关系较为复杂,但其部分相容体系的拉伸模量与组成呈线性关系.聚丙烯/聚酰胺1010及其共混物体系的屈服强度与共混物组成均呈线性关系.表征相结构的两相平均弦长比(l-1/-l2)与组成以及共混物体系力学性能与组成的关系,二者相似.同时讨论了体系力学性能随相尺寸等的变化规律.     

Morphology and properties of ternary polyamide 6/polyamide 66/elastomer blends

The aim of the work presented is to evaluate the mechanisms and phase interactions in ternary blends based on different polyamides and functionalised elastomers, and to establish a correlation between the morphology controlled by the specific binary interactions, and physical and technological properties, respectively. The properties of the ternary system polyamide 6/polyamide 66/ elastomer depend on the specific blend morphology which is determined mainly by the differences of the surface tension of the components. A phase‐in‐phase structure was observed by microscopic study (AFM) in the ternary polyamide 6/polyamide 66/elastomer blends with maleic anhydride grafted ethene‐octene copolymer, and a “quasi” phase‐in‐phase structure in blends with maleic anhydride grafted ethene‐propene‐diene copolymer as the elastomer phase. An incorporation of polyamide inside of the elastomer particles was observed in the first case due to the difunctionality of polyamide 66. This type of morphology causes an increased elongation at break and toughness of these blends. In comparison to the binary polyamide based blends the ternary blends show an increased elastic modulus, elongation at break and yield stress as well as a high impact strength at low temperatures up to ?20 °C. Copyright © 2003 John Wiley & Sons, Ltd.     

Enhancing toughness of poly (lactic acid)/Thermoplastic polyurethane blends via increasing interface compatibility by polyurethane elastomer prepolymer and its toughening mechanism

Due to the environmental pollution caused by the petroleum-based polymer, poly (lactic acid) (PLA), a biodegradable and biocompatible polymer that obtained from natural and renewable sources, has attracted widespread attention. However, the brittleness of PLA greatly limits its application. In this study, the super toughened PLA-based blends were obtained by compatibilizing the PLA/thermoplastic polyurethane (TPU) blends with the polyurethane elastomer prepolymer (PUEP) as an active compatibilizer. The mechanical properties, thermal properties and corresponding toughening mechanism of PLA/TPU/PUEP system were studied by tensile test, instrumented impact test, dynamic mechanical analysis (DMA), scanning electronic microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). All the results demonstrate that the isocyanate (−NCO) group in PUEP is successfully reacted with the –OH groups at both sides of the PLA and the obtained polyurethane (PU)~PLA copolymer (PU ~ cõ PLA) significantly improves the interfacial compatibility of PLA/TPU blends. The gradually refined dispersed phase size and fuzzy phase interface as displayed in SEM images suggest a good interfacial compatibilization in the PLA/TPU/PUEP blends, probably due to the isocyanate reaction between PLA and PUEP. And the interfacial reaction and compatibilization among the components led to the formation of super toughened PLA/TPU/PUEP blends. And the instrumented impact results indicate that most of the impact toughness is provided by the crack propagation rather than the crack initiation during the entire fracture process.     

Investigations on structure and properties of blends of polypropylene with polyamide 1010 by Rayleigh scattering

The phase structure and morphology of polypropylene （iPP） blends with poly（decamethylene sebacamide （polyamide 1010, PA 1010） and the part-compatible alloys （iPP/PA 1010/iPP-g-MAH） are investigated by Rayleigh scattering, i.e. small angle light scattering （SALS）. The structure parameters of SALS, i.e. correlation distance, ac and average chord lengths, /, are calculated. Their variation with the composition of the blends and alloys is discussed. The morphology and structure of fracture surfaces in the blends and alloys are studied by SEM images. The average diameter of dispersed phase in the blends and alloys is calculated by graph processing. The variation of average diameter is similar as that of average chord lengths of dispersed phases. The mechanical properties of the blends and alloys are analyzed and the relation of modulus and yield stress with the composition is studied. It is confirmed that the correlation between the modulus and the structure parameters is non-linear, while the correlation between the yield stress and the composition or structure parameters is linear.     

Morphology and mechanical and viscoelastic properties of natural rubber and styrene butadiene rubber latex blends

The morphology and mechanical and viscoelastic properties of a series of blends of natural rubber (NR) and styrene butadiene rubber (SBR) latex blends were studied in the uncrosslinked and crosslinked state. The morphology of the NR/SBR blends was analyzed using a scanning electron microscope. The morphology of the blends indicated a two phase structure in which SBR is dispersed as domains in the continuous NR matrix when its content is less than 50%. A cocontinuous morphology was obtained at a 50/50 NR/SBR ratio and phase inversion was seen beyond 50% SBR when NR formed the dispersed phase. The mechanical properties of the blends were studied with special reference to the effect of the blend ratio, surface active agents, vulcanizing system, and time for prevulcanization. As the NR content and time of prevulcanization increased, the mechanical properties such as the tensile strength, modulus, elongation at break, and hardness increased. This was due to the increased degree of crosslinking that leads to the strengthening of the 3‐dimensional network. In most cases the tear strength values increased as the prevulcanization time increased. The mechanical data were compared with theoretical predictions. The effects of the blend ratio and prevulcanization on the dynamic mechanical properties of the blends were investigated at different temperatures and frequencies. All the blends showed two distinct glass‐transition temperatures, indicating that the system is immiscible. It was also found that the glass‐transition temperatures of vulcanized blends are higher than those of unvulcanized blends. The time–temperature superposition and Cole–Cole analysis were made to understand the phase behavior of the blends. The tensile and tear fracture surfaces were examined by a scanning electron microscope to gain an insight into the failure mechanism. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2189–2211, 2000     

Compatibilization level effects on the structure and mechanical properties of rubber‐modified polyamide‐6/clay nanocomposites

Exfoliated polyamide‐6 (PA6)/organically modified montmorillonite clay (OMMT) nanocomposites (PNs) were modified with partially maleinized styrene–ethylene/butadiene–styrene triblock copolymers (SEBS) at three maleinization levels in an attempt to link in these materials high toughness with appropriate small‐strain and fracture tensile properties. OMMT stayed only in the PA6 matrix, and no preferential location in the matrix/rubber interphase was observed. The increased dispersed phase size upon the addition of OMMT was attributed to interactions between maleic anhydride (MA) functionalized SEBS and the surfactant of OMMT. The rubber particle size generally decreased when the MA content of SEBS increased, and this indicated compatibilization. The subsequent good adhesion led to tough nanocomposites across a wide range of both strain rates and fracture modes. As the critical interparticle distance (τ_c) decreased with the MA content, and the other parameters that could influence the surface‐to‐surface mean interparticle distance did not change, it is proposed that in these PNs higher adhesion leads to a smaller τ_c value. Finally, the presence in the matrix of a nanostructured clay makes the rubber content necessary for the toughness jump to increase and τ_c to decrease. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3611–3620, 2005     

Effects of compatibility of poly(l‐lactic‐acid) and thermoplastic polyurethane on mechanical property of blend fiber

Blending poly(l ‐lactic‐acid) (PLLA) and thermoplastic polyurethane (TPU) has been performed in an effort to toughen PLLA without compromising its biodegradability and biocompatibility. The mixing enthalpy calculation of PLLA and TPU predicted that the blend was a thermodynamic miscible system. The viscoelastic properties and phase morphologies of PLLA/TPU blends were investigated further by dynamic mechanical analysis and scanning electron microscopy. It was found that the blend was a partially miscible system. The dynamic mechanical analysis showed that T_g of PLLA and TPU shifted toward with TPU content increasing. Scanning electron microscopy photos showed that the morphologies of the blends changed from a sea island structure to a bicontinuous structure as an increment in TPU content, which suggested that the miscibility of PLLA and TPU was enhanced when the TPU increased. PLLA/TPU blend fibers were fabricated. With the TPU content increasing from 0 wt% to 30 wt%, the tensile strength and initial modulus of blend fibers decreased first then increased, while elongation at break and fracture work gradually increased. The change of tensile properties indicated the toughening effects of TPU on PLLA fibers, also suggested that the formation of blend fibers was influenced by the blend rheological behavior other than the compatibility. Copyright © 2014 John Wiley & Sons, Ltd.     

Atomic force microscopy study on blend morphology and clay dispersion in polyamide‐6/polypropylene/organoclay systems

The phase structure and clay dispersion in polyamide‐6(PA6)/polypropylene(PP)/organoclay (70/30/4) systems with and without an additional 5 parts of maleated polypropylene (MAH‐g‐PP) as a compatibilizer were studied with atomic force microscopy (AFM). AFM scans were taken from the polished surface of specimens that were chemically and physically etched with formic acid and argon ion bombardment, respectively. The latter technique proved to be very sensitive to the blend morphology, as PP was far more resistant to ion bombardment than PA6. In the absence of the MAH‐g‐PP compatibilizer, the organoclay is located in the PA6 phase; this finding is in line with transmission electron microscopic results. Further, the PP is coarsely dispersed in PA6 and the adhesion between PA6 and PP is poor. The addition of MAH‐g‐PP resulted in a markedly finer PP dispersion and good interfacial bonding between PA6 and PP. In this blend, the organoclay was likely dispersed in the PA6‐grafted PP phase. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43:1198–1204, 2005