Optimizing the balance between impact strength and stiffness in polypropylene/elastomer blends by incorporation of a nucleating agent

Isotactic polypropylene (iPP) blends were prepared with two different thermoplastic elastomers, a triblock copolymer styrene–ethylene butylene–styrene (SEBS) and a metallocenic ethylene‐octene copolymer (EO). The mechanical properties and morphology of blends with 0–50 wt% elastomer were studied to determine the influence of the presence of the elastomer on the improvement of toughness. The addition of a nucleating agent as a third component exerted a significant effect on the overall properties. Dynamic mechanical properties, flexural modulus, and impact strength as well as morphology were studied for nucleated and nonnucleated iPP/SEBS and iPP/EO blends. The improvement of impact properties found in binary blends was accompanied by a decrease in stiffness. However, the addition of the nucleating agent provided a good balance between impact strength and stiffness. From the results, SEBS was determined to be a better impact modifier for iPP than EO. The nucleated iPP/SEBS blends demonstrated improved mechanical properties compared with both the nucleated iPP/EO blends and the nonnucleated blends. POLYM. ENG. SCI., 48:80–87, 2008. © 2007 Society of Plastics Engineers     

Use of oxazoline functionalized polyolefins and elastomers as compatibilizers for thermoplastic blends

Oxazoline functionalized polypropylene, polyethylene, ethylene propylene copolymer (E/P), and styrene ethylene/butylene styrene copolymer (SEBS) were studied as compatibilizers in blends of polyolefins with polyesters and polyamides. The blends investigated were polypropylene/polyamide 6, polypropylene/polybutylene terephtalate, and polyethylene/polyamide 6, with engineering thermoplastic contents of 30 wt %. The blends were prepared in a twin-screw midiextruder, and injection molded with a mini-injection molding machine. The effect of compatibilizing on the morphology and mechanical properties of the blends was of interest. Compatibilization substantially improved the toughness of all tested blends. Their strength and stiffness remained at the level of the binary blends when polypropylene or polyethylene based compatibilizers were used, but slightly decreased with other compatibilizers. Morphological studies showed that the particle size was reduced, and the adhesion of the dispersed phase to the matrix improved by compatibilization. The effect of unfunctionalized polyethylene, polypropylene, E/P, and SEBS was also studied to compare the compatibilizers with them. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1923–1930, 1998     

Effects of extensional flow on properties of polyamide‐66/poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends: A study of morphology,mechanical properties,and rheology

In this study, polyamide‐66/poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PA66/PPO) blends with high viscosity ratio were processed by a self‐designed triangle‐arrayed triple‐screw extruder (TTSE, which simulates extensional flow) and a commercial twin‐screw extruder (TSE), respectively. Furthermore, in order to improve the mechanical properties of the immiscible PA66/PPO blends, PPO‐grafted maleic anhydride (PPO‐g‐MA) and styrene–ethylene–butylene–styrene (SEBS) block copolymer were used. The mechanical properties, phase morphology, and rheological properties of both binary PA66/PPO blends and toughened PA66/PPO/PPO‐g‐MA blends were comprehensively investigated to compare the above mentioned two processing method. Samples processed with TTSE exhibited better mechanical properties than the TSE‐processed blends. The morphologies of the blends were examined by scanning electron microscopy, exhibiting smaller particles sizes and narrower particle size distributions, which were attributed to the significant effects of extensional flow in TTSE. The toughening mechanism of compatibilized blends was investigated through morphology analysis, dynamic mechanical, and rhelogical analysis. Thus, TTSE with an extensional effect was proved to be efficient in the blending of high viscosity ratio polymers. POLYM. ENG. SCI., 57:1090–1098, 2017. © 2016 Society of Plastics Engineers     

Preparation and balanced mechanical properties of solid and foamed isotactic polypropylene/SEBS composites

This study presents a self-designed foaming apparatus and routes to manufacture foamed isotactic polypropylene (iPP) blends with uniform and dense cells, using styrene-ethylene-butadiene-styrene (SEBS) block copolymer as toughening additive. The addition of SEBS can clearly enhance the impact strength of solid iPP, iPP blends with a 20 wt% SEBS has obtained high notched impact strength of 75 kJ/m², which is ca. 16 times larger than that of neat iPP. Relatively fine microcellular iPP-SEBS foams with the average cell size of several micrometers, and the cell density of 10⁹ cells/cm³ were fabricated using a batch foaming procedure. Moreover, using our self-designed mold and compression foaming method, iPP-SEBS foams with balanced mechanical properties were produced. With the increasing of SEBS, tensile strength and flexural strength were slightly decreased, but the impact strength was increased clearly. The balanced mechanical properties between stiffness and toughness were achieved after compression foaming.     

Microstructural characteristics of glass bead‐ and wollastonite‐filled isotactic‐polypropylene composites modified with thermoplastic elastomers

Microstructural characteristics of isotactic‐polypropylene/glass bead (iPP/GB) and iPP/wollastonite (iPP/W) composites modified with thermoplastic elastomers, poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) copolymer (SEBS) and corresponding block copolymer grafted with maleic anhydride (SEBS‐g‐MA), were investigated. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and dynamic mechanical analyses (DMA) showed that the iPP/SEBS and iPP/SEBS‐g‐MA blends were partially compatible two‐phase systems. Well‐dispersed spherical GB and acicular W particles without evidence of interfacial adhesion were observed in the iPP/GB and iPP/W binary composites respectively. Contrary to the blends, melt flow rates of the iPP/GB and PP/W composites decreased more with SEBS‐g‐MA than with SEBS because of enhanced interfacial adhesion with SEBS‐g‐MA elastomer. The SEM analyses showed that the ternary composites containing SEBS exhibited separate dispersion of the rigid filler and elastomer particles (i.e., separate microstructure). However, SEBS‐g‐MA elastomer not only encapsulated the spherical GB and acicular W particles completely with strong interfacial adhesion (i.e., core‐shell microstructure) but also dispersed separately throughout iPP matrix. In accordance with the SEM observations, the DSC and DMA revealed quantitatively that the rigid filler and SEBS particles in iPP matrix acted individually, whereas the rigid filler particles in the ternary composites containing SEBS‐g‐MA acted like elastomer particles because of the thick elastomer interlayer around the filler particles. The Fourier transform infrared analyses revealed an esterification reaction inducing the strong interfacial adhesion between the SEBS‐g‐MA phase and the filler particles. POLYM. COMPOS., 31:1265–1284, 2010. © 2009 Society of Plastics Engineers     

SEBS/PPO共混物的相态结构及力学性能和流变性能 研究

将不同配比的苯乙烯-乙烯-丁二烯-苯乙烯嵌段共聚物（SEBS）/聚苯醚 （PPO）通过同向双螺杆挤出机进行熔融共混。应用原子力显微镜（AFM）观察了SEBS/PPO不同配比的相态结构,并比较了其力学性能,同时还比较了不同充油量的SEBS/PPO共混物的相态结构、力学性能和流变性能。结果表明,随着PPO含量的增加,亮点聚苯乙烯（PS）段逐渐增加,PPO和PS完全融合到一起,当SEBS/PPO＝80/20时乙烯-丁二烯（EB）段是连续相,PS相和PPO是分散相;当SEBS/PPO＝20/80时发生相反转,PPO变为连续相;随着PPO含量的增加,拉伸强度大幅度增加,断裂伸长率明显降低;随着充油量的增加,拉伸强度和断裂伸长率均有不同程度的下降;表观黏度随非牛顿剪切速率的增加逐渐降低。     

Relationship between structure and properties in high‐performance PA6/SEBS‐g‐MA/(PPO/PS) blends: The role of PPO and PS

This work aimed at studying the role of poly(phenylene oxide) (PPO) and polystyrene (PS) in toughening polyamide‐6 (PA6)/styrene‐ethylene‐butadiene‐styrene block copolymer grafted with maleic anhydride (SEBS‐g‐MA) blends. The effects of weight ratio and content of PPO/PS on the morphology and mechanical behaviors of PA6/SEBS‐g‐MA/(PPO/PS) blends were studied by scanning electron microscope and mechanical tests. Driving by the interfacial tension and the spreading coefficient, the “core–shell” particles formed by PPO/PS (core) and SEBS‐g‐MA (shell) played the key role in toughening the PA6 blends. As PS improved the distribution of the “core–shell” particles due to its low viscosity, and PPO guaranteed the entanglement density of the PPO/PS phase, the 3/1 weight ratio of PPO/PS supplied the blends optimal mechanical properties. Within certain range, the increased content of PPO/PS could supply more efficient toughening particles and bring better mechanical properties. Thus, by adjusting the weight ratio and content of PPO and PS, the PA6/SEBS‐g‐MA/(PPO/PS) blends with excellent impact strength, high tensile strength, and good heat deflection temperature were obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45281.     

Use of SEBS/EPR and SBR/EPR as Binary Compatibilizers for PE/PP/PS/HIPS Blends: A Work Oriented to the Recycling of Thermoplastic Wastes

Recycling of thermoplastic wastes consisting of PE/PP/PS/HIPS blends was investigated by using SEBS/EPR and SBR/EPR as compatibilizers. The effect of the binary compatibilizer systems and processing conditions on the mechanical properties and morphology of the blends are discussed. The SEBS/EPR system allowed blends with better mechanical properties to be obtained than the SBR/EPR system; this was attributed to the chemical structure similarity between compatibilizers and recycled materials. The optimal conditions for processing of the recycled thermoplastics (blends) were found to be 190 °C, 14 min of processing time and 3.5 wt.‐% of compatibilizer. The morphology and mechanical properties of the blends were discussed using theoretical phase diagrams and models proposed in the literature, and good agreements between these properties were found.

     

Toughening and compatibilization of polyphenylene sulfide/nylon 66 blends with SEBS and maleic anhydride grafted SEBS triblock copolymers

In this study, styrene‐b‐ethylene/butylene‐b‐styrene triblock copolymer (SEBS) and maleic anhydride grafted SEBS (SEBS‐g‐MA) were used as compatibilizers for the blends of polyphenylene sulfide/nylon 66 (PPS/PA66). The mechanical properties, including impact and tensile properties and morphology of the blends, were investigated by mechanical properties measurements and scanning electron microscopy. Impact measurements indicated that the impact strength of the blends increases slowly with elastomer (SEBS and SEBS‐g‐MA) content upto 20 wt %; thereafter, it increases sharply with increasing elastomer content. The impact energy of the elastomer‐compatibilized PPS/PA66 blends exceeded that of pure nylon 66, implying that the nylon 66 can be further toughened by the incorporation of brittle PPS minor phase in the presence of SEBS or SEBS‐g‐MA. The compatibilization efficiency of SEBS‐g‐MA for nylon‐rich PPS/PA66 was found to be higher than SEBS due to the in situ forming SEBS interphase between PPS and nylon 66. The correlation between the impact property and morphology of the SEBS‐g‐MA compatibilized PPS/PA66 blends is discussed. The excellent impact strength of the nylon‐rich blends resulted from shield yielding of the matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

HPVC/SBR共混体系相容性的研究

采用动态硫化方法制备高聚合度聚氯乙烯（ＨＰＶＣ）／ＳＢＲ共混型热塑性弹性体,考察了单一组分相容剂「相容剂分别为ＮＢＲ２７０、ＮＢＲ Ｐ６５、ＣＰＥ和氢化苯乙烯－丁二烯、苯乙烯嵌段共聚物（ＳＥＢＳ）」、复合相容剂（ＳＥＢＳ／ＮＢＲ和ＣＰＥ／ＮＢＲ）及交联程度对ＨＰＶＣ／ＳＢＲ共混体系相容性的影响。结果表明,使用复合相容剂可明显改善ＨＰＶＣ／ＳＢＲ共混物的性能;动态硫化在改善共混物力学性能方面起主要作     

The role of the compatibilizer on the microindentation hardness of iPP/PC blends

Blends of isotactic polypropylene (iPP) and polycarbonate (PC) with and without a compatibilizer were prepared using a Brabender Haake Rheocord at 260°C and 32 rpm. Maleic anhydride grafted styrene‐ethylene/butylene‐styrene (SEBS‐g‐MAH) and maleic anhydride grafted ethylene–propylene diene (EPDM‐g‐MAH) were chosen as compatibilizers and their proportion was set to 5, 10, and 15 wt%, respectively. The thermal properties and crystallization behavior were determined by differential scanning calorimetry (DSC) and wide angle X‐ray scattering (WAXS). Micromechanical properties were also investigated using a Vickers microindentation tester. The DSC analysis indicates that the melting temperature of iPP in the all the blends, compatibilized and uncompatibilized ones, remains constant and is almost the same as those of the pure component. On the other hand, it is shown that the degree of crystallinity of iPP in the blends calculated by DSC and WAXS is dependent of the composition of the polymeric mixture. However the hardness (H) decreases with increasing PC content until the composition of iPP/PC (75/25) is reached, whereas for larger PC content values, H increases. The same trend was obtained with the addition of both compatibilizers. POLYM. ENG. SCI., 56:1138–1145, 2016. © 2016 Society of Plastics Engineers     

复配增容剂增容PPO/PP/GF研究

研究复配增容剂(SEPS/PP-g-MAH)对玻璃纤维(GF)增强聚苯醚(PPO)/聚丙烯(PP)力学性能、熔体流动性以及耐热性能的影响,并用扫描电子显微镜观察了不同共混体系的形态结构.结果表明,复配增容剂改善了PPO/PP/GF共混体系的相容性,提高了共混体系的拉伸强度、弯曲强度、冲击强度和熔体流动速率,但同时降低了...     

SEBS对iPP/NX8000K组合物透明性能和力学性能的影响

为了增强等规聚丙烯（iPP）的透明性能和冲击性能，采用物理共混方法，将弹性体氢化聚苯乙烯—丁二烯—聚苯乙烯嵌段共聚物（SEBS）与NX8000K成核剂配合使用对iPP进行改性。通过差示扫描量热分析（DSC）和X射线衍射分析（XRD）、偏光显微镜分析（POM）等方法研究了SEBS对iPP/NX8000K组合物的结晶行为、透明性能和力学性能的影响。结果表明：在NX8000K含量为0.6 %（质量分数，下同），SEBS用量为40 %时，iPP/NX8000K/SEBS三元组合物的雾度降至24.9 %，比纯iPP降低了54.7 %；冲击强度增至50.7 kJ/m2，与纯iPP相比提高了10倍。     

Influence of processing conditions on mechanical properties of blends of styrenic block copolymer and poly(phenylene oxide): Miscibility and microdomain size

The effect of processing conditions on mechanical properties of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) and poly(2,6‐dimethy‐1,4‐phenylene oxide) (PPO) blends were investigated. Differential scanning calorimetry and small angle X‐ray scattering were used to study the miscibility and d‐spacing of the blends. The processing temperature plays an important role in mechanical properties. PPO works as filler and weakens mechanical properties when the processing temperature is below 230 °C. As the processing temperature exceeds 230 °C, PPO incorporates into the PS blocks of SEBS and the performance enhances with increasing temperature due to a better miscibility. The strong shear stress is beneficial to the dispersion of PPO into SEBS matrix and more PPO incorporates into PS blocks during melt processing, resulting in the better mechanical properties and a larger d‐spacing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46123.     

Onset critical strains as an effective parameter for compatibilizer efficiency in a polypropylene-poly(ethylene terephthalate) blend

The effectiveness of a compatibilizer is responsible for improved mechanical properties of immiscible blends. The enhanced interactions between the phases are assessed via critical plastic strain (onset of fine slip caused by local intra-/interlamellar slip) and critical elastic strain (onset of fibrillation of crystalline skeleton). Polypropylene-poly(ethylene terephthalate) (PP-PET) blends were compatibilized with three maleic anhydride grafted compatibilizers with different backbones: PP, SEBS, and POE. Using this critical onset strain method, via free shrinkage experiments, allowed to identify the effect of PET on the matrix's deformation and also the different contributions of the compatibilizers to the deformation mechanisms. Results showed that PPgMAH promoted best PET's plastic deformation to the matrix, relative to the other compatibilizers. However, SEBSgMAH's elastomeric backbone provide better stress dissipation before onset of fibrillation compared to the binary blend and matrix. This method can be used as a way to assess the effectiveness of a compatibilizer in an immiscible blend.     

Phase structure and viscoelastic properties of compatibilized blends of PET and HDPE recyclates

Immiscible blends of recycled poly(ethylene terephthalate) (R‐PET), containing some amount of polymeric impurities, and high‐density polyethylene (R‐PE), containing admixture of other polyolefins, in weight compositions of 75 : 25 and 25 : 75 were compatibilized with selected compatibilizers: maleated styrene–ethylene/butylene–styrene block copolymer (SEBS‐g‐MA) and ethylene–glycidyl methacrylate copolymer (EGMA). The efficiency of compatibilization was investigated as a function of the compatibilizer content. The rheological properties, phase structure, thermal, and viscoelastic behavior for compatibilized and binary blends were studied. The results are discussed in terms of phase morphology and interfacial adhesion among components. It was shown that the addition of the compatibilizer to R‐PET‐rich blends and R‐PE‐rich blends increases the melt viscosity of these systems above the level characteristic for the respective binary blends. The dispersion of the minor phase improved with increasing compatibilizer content, and the largest effects were observed for blends compatibilized with EGMA. Calorimetric studies indicated that the presence of a compatibilizer had a slight affect on the crystallization behavior of the blends. The dynamic mechanical analysis provided evidence that the occurrence of interactions of the compatibilizer with blend components occurs through temperature shift and intensity change of a β‐relaxation process of the PET component. An analysis of the loss spectra behavior suggests that the optimal concentration of the compatibilizers in the considered blends is close to 5 wt %. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1423–1436, 2001     

Influence of coalescence and interfacial tension on the morphology of PP/HDPE compatibilized blends

In this paper, the compatibilization of polypropylene (PP)/high-density polyethylene (HDPE) blend was studied through morphological and interfacial tension analysis. Three types of compatibilizers were tested: ethylene-propylene-diene copolymer (EPDM), ethylene-vinylacetate copolymer (EVA) and styrene-ethylene/butylene-styrene triblock copolymer (SEBS). The morphology of the blends was studied by scanning electron microscopy. The interfacial tension between the components of the blends was evaluated using small amplitude oscillatory shear analysis. Emulsion curves relating the average radius of the dispersed phase and the interfacial tension to the compatibilizer concentration added to the blend were obtained. It was shown that EPDM was more efficient as an emulsifier for PP/HDPE blend than EVA or SEBS. The relative role of interfacial tension reduction and coalescence reduction to particle size reduction was also addressed. It was observed that the role of coalescence reduction is small, mainly for PP/HDPE (90/10) blends compatibilized by EPDM, EVA or SEBS. The results indicated that the role of coalescence reduction to particle size reduction is lower for blends for which interfacial tension between its components is low at compatibilizer saturation.     

Blends of SBS triblock copolymer with poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polystyrene mixture

Blends of styrene–butadiene–styrene (SBS) or styrene–ethylene/1‐butene–styrene (SEBS) triblock copolymers with a commercial mixture of polystyrene (PS) and poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) were prepared in the melt at different temperatures according to the chemical kind of the copolymer. Although solution‐cast SBS/PPO and SBS/PS blends were already known in the literature, a general and systematic study of the miscibility of the PS/PPO blend with a styrene‐based triblock copolymer in the melt was still missing. The thermal and mechanical behavior of SBS/(PPO/PS) blends was investigated by means of DSC and dynamic thermomechanical analysis (DMTA). The results were then compared to analogous SEBS/(PPO/PS) blends, for which the presence of a saturated olefinic block allowed processing at higher temperatures (220°C instead of 180°C). All the blends were further characterized by SEM and TGA to tentatively relate the observed properties with the blends' morphology and degradation temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2698–2705, 2003     

Localized compatibilization in immiscible blends of thermoplastic polyurethane and ethylene‐octylene copolymer

To prepare thermoplastic polyurethane (TPU)/ethylene‐octylene copolymer (POE) blends, which are thermodynamically immiscible, maleated POE and aminated POE were incorporated as compatibilizers. Effect of addition of the compatibilizers and their contents on morphology, coalescence, and mechanical properties of TPU/POE blends were investigated. The microstructural observation revealed that the compatibilizers are located at the interface in the blends, forming a stable interfacial layer. As a result, the dispersed phase particle size was greatly reduced and tensile properties of the blends were significantly improved. POE‐NH₂ provides the blends with higher compatibility than POE‐MA. The interfacial interaction offered by the compatibilizers was found to be a function of the amount of the reactive groups grafted onto POE. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with polystyrene-based thermoplastic rubbers: A comparative study

This work presents the first part of our study on the modification of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with styrenic thermoplastic rubbers. Polystyrene-b-polyisobutylene-b-polystyrene (SIBS), polystyrene-b-polybutadiene-b-polystyrene (SBS) and polystyrene-b-poly(ethylene/butylene)-b-polystyrene (SEBS) triblock copolymers were melt blended with PPO and the blends were characterized. Differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and transmission electron microscopic (TEM) studies revealed that PPO/SEBS blends displayed the most pronounced phase-separated morphology with largest rubbery domains. SBS showed the most miscibility, and the least detrimental effect on dynamic mechanical properties and tensile strength. The results of this comparative study guided us to develop optimum conditions for the impact modification of PPO by SIBS thermoplastic rubbers.