Study on phase structure and evolution of PP/PEOc blends during heat preservation process under quiescent condition

The phase structure and evolution of polypropylene (PP)/poly(ethylene-1- octene) copolymer (PEOc) blends during heat preservation process under quiescent condition were studied using scanning electron microscopy (SEM). The structure parameters, such as the average area diameter d _p , characteristic length L, and average characteristic length L _m , of the dispersed phase in PP/ PEOc blends were calculated by pattern analysis of SEM images. Moreover, the potential fractal behavior of the phase structure and morphology of polymer blends during the process was discussed. The histograms of P(L(t)/L _m ) obtained at various time fell on a master curve, demonstrating the self-similar growth of the phase structure of the blends during heat preservation process.     

Refractive index crossover and the phase diagram of an iPP/PEOc blend

The phase diagram of an isotactic polypropylene/poly(ethylene-octene) copolymer (iPP/PEOc) blend system was investigated using phase contrast optical microscopy, laser light scattering and differential scanning calorimetry (DSC). The sample goes through immiscible (opaque) region to transparent region (seemingly miscible) and back to immiscible (opaque) again as temperature increases through 300 °C region. But it turns out that this is not a real one phase region. It is caused by a temperature dependent inversion of refractive indices between the two component polymers, which can be easily misinterpreted as a miscible region between an upper critical solution temperature (UCST) state and a lower critical solution temperature (LCST) state. With a proper interpretation and analysis of this refractive index inversion, the UCST phase diagram of this iPP/PEOc blend system has been obtained.     

Power consumption characteristics of an in‐line silverson high shear mixer

In‐line rotor stator mixers differ from in‐tank versions because the flow is often controlled independently of the rotor speed. For in‐tank devices the turbulent power can be adequately described by single impeller type power number. For an in‐line rotor‐stator mixer it is found that the power transmitted by the rotor consists of a power term and a flow term. The constants in this expression are normally obtained from a multilinear regression of a large matrix of experiments. Two simplified methods of obtaining these constants from limited data sets by (1) torque measurement and (2) by heat balance are described herein. These are used to determine the constants for a Silverson 150/250 MS inline mixer with different rotor stator arrangements from the laminar to turbulent regimes. The power and Metzner‐Otto constants determined are shown to be in good agreement to data for a larger matrix of experimental data. © 2011 American Institute of Chemical Engineers AIChE J, 58: 1683–1692, 2012     

Clay locked phase morphology in the PPS/PA66/clay blends during compounding in an internal mixer

In this communication, we will demonstrate, by using poly(p-phenylene sulfide) (PPS)/polyamide66 (PA66) blends as an example, the clay can not only affect the phase morphology in immiscible polymer blends, but also frozen in the phase inversion. By adjusting the processing method, an inversed phase, where the minor component PA66 forms the continue phase and the major component PPS forms the dispersed phase, is observed for the first time. This is explained as due to the locking effects of clay layers on the phase development. The result is interesting and also very important, which provides a new way to control the phase morphology and phase inversion in immiscible polymer blends by using clay.     

PP/PS共混熔纺中相结构沿纺程的梯度演变

将聚丙烯(PP)/聚苯乙烯(PS)按质量比92∶8进行共混纺丝,以自制的纺程取样器对PP/PS熔融纺丝进行纺程取样,利用冷冻超薄切片机获得纺程各点取样纤维的横截面和纵剖面,扫描电子显微镜观察纤维中PS分散相的形貌,研究了共混熔融纺丝中梯度结构沿纺程的演变及其梯度结构的形成机理。结果表明:PS分散相数目沿纤维径向呈现内密外疏的梯度分布,这一差异沿着纺程不断增大;PS分散相在纺程0~60 cm发生形变,纺丝速度为125~500 m/min下PS分散相直径逐渐减小,当纺丝速度达到1 000 m/min时,PS分散相直径在纺程0~20 cm减小,在纺程20~60 cm增加,PS分散相液滴在此区域发生了明显的聚并,在纤维表层各个纺丝速度下分散相都呈现不同程度的聚并现象;在PP/PS共混纤维中呈现中心层分散相液滴形变程度大表层形变程度小的梯度差异,但高速纺丝会弱化这一差异。     

Shear‐induced migration of nanoclay during morphology evolution of PBT/PS blend

Three different poly(imide-siloxane)s (PIS) containing rigid imide groups were synthesized by the reaction of amine end-capped imides to the siloxane backbone. These highly soluble amine terminated imides were synthesized by reacting fluorinated anhydride and three different amines (DDBP, DDM, DBP). The imides were grafted to the siloxane backbone by the epoxy group cleavage. All the polymers were obtained in quantitative yields with the inherent viscosities ranging from 0.32 to 0.45 dL/g. The polymers were characterized by FTIR, ¹H and ¹³C NMR, and their thermal properties were studied. The DSC results showed two distinct glass transition temperatures demonstrating the existence of phase separation between the hard imide and soft siloxane groups. Polymeric membranes were prepared employing the coupling reaction between PIS and the polydimethylsiloxane matrix by varying the amount of incorporation of PIS. The membranes showed a high tensile strength of 82 MPa. The contribution of polar and dispersion component towards the total surface energy was studied by the contact angle measurements, and a reduction in surface tension of 15 mN/m was achieved with the fluorine containing PIS membrane. The study of the surface morphology was studied which confirmed the existence of phase separation in these systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

LDA measurements and CFD simulations of an in‐line high shear mixer with ultrafine teeth

Hydrodynamics of a pilot‐scale in‐line high shear mixer (HSM) with double rows of ultrafine rotor and stator teeth, including the velocity profiles and power consumptions, were measured using laser Doppler anemometry and a torque transducer, respectively. Computational fluid dynamics simulations were conducted using the standard k‐ε turbulence model with first‐ and second‐order accuracy and large eddy simulation (LES) with the standard Smagorinsky–Lilly subgrid scale model. Predictive capabilities of the different turbulence models and discretization schemes were assessed based on the experimental data. It is found that the current LES can predict accurately the flow patterns for the strongly rotating and locally anisotropic turbulent flows in the complex in‐line HSM. The results obtained are fundamental to explore potential applications of the in‐line teethed HSMs to intensify chemical reaction processes. © 2013 American Institute of Chemical Engineers AIChE J, 60: 1143–1155, 2014     

Effect of cross‐linked LLDPE/PP blend (LLDPE‐PP) as compatibilizer on morphology,crystallization behavior and mechanical property of LLDPE/PP blends

Moderate cross‐linked blend (LLDPE‐PP) of linear low‐density polyethylene (LLDPE) and polypropylene (PP) with benzoyl peroxide (BPO) were prepared by the reactive melt mixing in HAAKE mixer. Effect of LLDPE‐PP as compatibilizer on the morphology, crystallization behavior and mechanical properties of LLDPE/PP (87/13) blends were studied using scanning electron microscopy (SEM), polarized optical microscopy (POM), wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC) and mechanical testing machines. The results showed that LLDPE‐PP not only improved the interfacial adhesion between the LLDPE and PP but also acted as selective nucleating agent for crystal modification of PP. In the blends, the sizes of LLDPE and PP spherulites became smaller, and their melting enthalpies reduced in the presence of LLDPE‐PP. Furthermore, the mechanical properties of LLDPE/PP blends were improved with the addition of LLDPE‐PP, and when the concentration of LLDPE‐PP was 2 phr, the ternary blend had the best mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

PP/POE/PA6三元共混物相形态的预测及受混炼顺序的影响

引言对聚合物进行共混是改善其性能的重要方法,多元聚合物共混物结合了多种聚合物的优点,具有更多独特的性能,因此对多元尤其是三元共混物的研究越来越多[1-5]。聚合物共混物的相形态对其性能有着决定性的影响[6-9],因而相形态是共混物研究的一个非常重要的方面[9-12]。     

Melt rheology and morphology of PP/SEBS/PC ternary blend

Melt rheological properties of the ternary blend of isotactic polypropylene (PP), styreneethylene–butylene–styrene terpolymer (SEBS), and polycarbonate (PC), PP/SEBS/PC, are studied in a wide range of composition, such that PP is the matrix and SEBS and PC are the minor components, with the proportion of one varying from 0 to 30% at various fixed compositions of the other. The respective binary blends, PP/SEBS and PP/PC, studied as the reference systems for interpretation of results on the ternary blends yielded interesting new information about the morphology development and its correlation with melt rheological properties of these binary blends. The studies include the measurement of melt rheological properties on a capillary rheometer in the shear rate range 10¹–10⁴ s^?1 at a fixed temperature of 240°C. The data presented as conventional flow curves are analyzed for the effect of blend composition and shear rate on pseudoplasticity, melt viscosity, and melt elasticity, and role of each individual component is identified. Morphology of dispersed phases of these blends is studied through scanning electron microscopy of the cryogenically fractured and suitably etched surfaces. Variations of morphology with blend composition and shear rate showed interesting correlation with melt rheological properties, which are discussed in detail. An important finding of the morphological studies is that in the PP/SEBS/PC ternary blend the SEBS phase forms two types of morphologies depending on the blend composition and shear rate: (i) simple droplets and (ii) boundary layer at the surface of the PC droplets. © 1993 John Wiley & Sons, Inc.     

Effect of phase separation on spherulitic growth rate of PP/EPR in‐reactor alloys

In this work, the effect of phase separation on the spherulitic growth rate of a polypropylene/ethylene–propylene random (PP/EPR) copolymer in‐reactor alloy was investigated. The PP/EPR in‐reactor alloy was either directly quenched from homogeneous melt to crystallization temperature or held at various temperatures for phase separation prior to crystallization. It is found that at lower crystallization temperatures previous phase separation in the melt retards the crystallization rate. The higher the phase separation rate, the smaller the spherulitic growth rate. This can be attributed to faster crystallization rate than the rate of secondary phase separation. The composition of the PP‐rich phase and corresponding depression of the equilibrium melting temperature of PP vary with phase separation temperature. On the other hand, at higher crystallization temperature, previous phase separation in the melt has little effect on the spherulitic growth rate because secondary phase separation can take place prior to crystallization. The transition temperature from regime II to regime III also shifts to lower temperature as the phase separation temperature increases. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

In situ control of co‐continuous phase morphology for PS/PS‐co‐TMI/PA6 blend

The emulsification efficiency of PS‐co‐TMI, a copolymer polymerized by styrene and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI), for polystyrene (PS)/polyamide 6 (PA6) blend was studied. During the mixing process, an effective emulsifier PS‐g‐PA6 was generated, which was demonstrated by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy. PS‐g‐PA6 generated by PS‐co‐TMI with high TMI content was found to contain some unreacted isocyanate active groups which reduced using efficiency of PS‐co‐TMI. Irrespective of TMI content in PS‐co‐TMI, the dosage of PS‐co‐TMI reached 20 wt %, unreacted PS‐co‐TMI was detected. These results indicated that reactive emulsification limits for both active groups' content and reactive precursors' dosage. After the rational addition of PS‐co‐TMI into PS/PA6 system, phase sizes of co‐continuous structure were reduced conspicuously. However, co‐continuous structure was evolved into matrix‐dispersed structure while the dosage of PS‐co‐TMI reached 20 wt %. Emulsification efficiencies of PS‐co‐TMI with different TMI contents, 2.2, 4.1, and 7.5 wt %, were compared. The results revealed PS‐co‐TMI with 2.2 wt % TMI content had the highest reactive emulsification efficiency because of the block‐copolymer‐inclined emulsifier generated in the mixing process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39972.     

Dynamic shear rheological behavior of PP/EPR in‐reactor alloys synthesized by multi‐stage sequential polymerization process

The rheological behavior, morphology, and mechanical properties of in‐reactor alloy of polypropylene (PP)/ethylene propylene rubber (EPR) synthesized by multi‐stage sequential polymerization process are studied in this article. The relationship between polymerization parameters, morphology, and rheological properties are evaluated by scanning electron microscopy (SEM) and small amplitude oscillation rheometry in the linear viscoelastic region. The electron microscopy of samples is showed that by increasing switching frequency in polymerization time, the size of EPR particles decrease. By increasing switching frequency, the curves of complex viscosity against angular frequency of samples are shifted to higher values at low range of shear rates with no significant change at higher frequencies in Power‐law region. The modified Cole‐Cole plots revealed the enhanced melt elasticity by increasing switching frequency up to 230°C. The plot of phase angle versus absolute value of complex modulus G* is used for the evaluation of matrix‐droplets interaction at various temperatures. It is observed two different behaviors before and after 230°C which is the evidence of the change in relaxation mechanism of the blend components because of coarsening the rubber particles in the phase separation process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

PA6/PE共混纺丝中圆盘静态混合器的应用研究

采用聚己内酰胺/聚乙烯(PA6/PE)熔体共混纺丝,对纺丝组件中装有不同套数的圆盘静态混合器的应用效果进行了研究。结果表明:纺丝组件中装了圆盘静态混合器,与原组件相比,其PA6,PE共混的分布均匀性及细化程度较好;静态混合圆盘的数量越多,共混物料的分布均匀性与细化程度越好;装有3套(6块)静态混合圆盘的应用效果较好,所得PA6/PE共混纤维横截面及纵向表面规整,没有孔洞,纺丝时无断头,卷绕成形良好。     

聚丙烯/聚苯乙烯共混熔纺中分散相的形态演变

采用共混熔融纺丝法制备聚丙烯(PP)/聚苯乙烯(PS)共混纤维,在纺程上不同位置收集纤维,研究了纺程上分散相PS的形态演变以及共混组成和拉伸比对形态变化的影响。结果表明:纺程上分散相由挤出丝中的球形变为卷绕丝中的椭球形;随着分散相含量的增加,挤出丝中分散相数目增多,分散相之间发生聚并,直径增加,纺丝过程中在拉伸应力作用下,分散相发生形变;随着拉伸比的增加,卷绕丝中分散相长径比增加,分布变宽。     

水辅助注塑PP/EVOH共混物制品的相形态与阻渗性能

选择3种不同黏度的聚丙烯(PP)与聚乙烯醇(EVOH)共混制备质量比为90/10的共混物,并采用水辅助注塑(WAIM)将这3种共混物成型为中空制品。从WAIM制品靠近浇口(1^#)和末端(2^#)两个位置取出样品,通过扫描电镜观察样品壁厚上3个位置的相形态,并测试所取样品的甲苯渗透率。借助WAIM中高压水作用下模腔内熔体的流场对样品中3个位置的相形态进行了分析。对WAIM的高黏度比共混物制品2^#样品,在外表层和内表层分散相呈粗纤维状,芯层主要呈液滴状,其阻渗性能与相应的WAIM PP样品比有适度提高(约2.4倍);对WAIM的2种低黏度比共混物制品2^#样品,外表层和内表层分散相呈细纤维状,芯层呈粗长纤维状,其阻渗性能与相应的WAIM PP样品比提高幅度较大(其中对黏度比最小的共混物达9.8倍)。1^#位置所取3种WAIM PP/EVOH样品中分散相纤维的平均直径比2^#位置的大,导致1^#位置所取样品的阻渗性能比2^#位置的低。     

Effect of compatibilizer on micromehanical deformations and morphology of dispersion in PP/PDMS blend

Role of maleic anhydride grafted polypropylene (PP‐g‐MAH) in interface modification in polypropylene (PP)/poly(dimethylsiloxane) (PDMS) elastomer blend has been investigated in this article through its effects on morphology of dispersion, micromechanical deformations such as voiding, crazing, shear yielding, fibrillation, and tensile behavior. During tensile deformation, PP/PDMS blend without the compatibilizer showed debonding at the elastomer‐matrix interface and it induced shear yielding and subsequently fibrillation in the matrix. The compatibilizer improved the interfacial adhesion between the PDMS domains and PP matrix, which prevented the debonding at elastomer‐matrix interface and the resulting shear yielding, and fibrillation was absent and rather caused extensive crazing in the matrix. Addition of PP‐g‐MAH reduced the size of dispersed PDMS domains, and narrowed the domain size distribution, which is attributed as an effect of interfacial adhesion produced by PP‐g‐MAH. Stress–strain curve and fibrillation also show similar effect of the interfacial adhesion caused by the compatibilizer. All these observations consistently lead to conclude that PP‐g‐MAH acts as a good compatibilizer for PP/PDMS blend. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

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.     

Processing‐improved properties and morphology of PP/COC blends

The aim of this study was to improve mechanical properties of polypropylene/cycloolefin copolymer (PP/COC) blends by processing‐induced formation of long COC fibers. According to the available literature, the fibrous morphology in PP/COC blends was observed just once by coincidence. For this reason, we focused our attention on finding processing conditions yielding PP/COC fibrous morphology in a well‐defined, reproducible way. A number of PP/COC blends were prepared by both compression molding and injection molding (IM). Neat polymers were characterized by rheological measurements, whereas phase morphology of the resulting PP/COC blends was characterized by means of scanning electron microscopy (SEM). The longest COC fibers were achieved in the injection molded PP/COC blends with compositions 75/25 and 70/30 wt %. Elastic modulus and yield strength of all blends were measured as functions of the blend composition using an Instron tensile tester; statistically significant improvement of the yield strength due to fibrous morphology was proved. Moreover, two different models were applied in the analysis of mechanical properties: (i) the equivalent box model for isotropic blends and (ii) the Halpin‐Tsai model for long fiber composites. In all PP/COC blends prepared by IM, the COC fibers were oriented in the processing direction, as documented by SEM micrographs, and acted as a reinforcing component, as evidenced by stress–strain measurements. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Time evolution of phase structure and corresponding mechanical properties of iPP/PEOc blends in the late-stage phase separation and crystallization

A typical toughened polymeric alloy system, isotactic polypropylene (iPP)/poly(ethylene-co-octene) (PEOc) blend, was selected in this study to investigate the influence of phase separation and crystallization on the final mechanical properties of the polyolefin blend. The time dependence of the morphology evolution of this iPP/PEOc blend with different compositions was annealed at both 200 and 170 °C and investigated with scanning electron microscopy (SEM) and phase contrast optical microscopy (PCOM). It was found that under the above two phase separation temperatures, the domain size of iPP80/PEOc-20 (PEOc-20) increases only slightly, while the structure evolution of iPP60/PEOc-40 (PEOc-40) is quite prominent. The tensile tests revealed that the mechanical properties of PEOc-20, including break strength and elongation at break decrease only in a very small amount, while those of PEOc-40 are depressed obviously with phase separation time. The decrease of interphase and a sharper boundary resulting from domain coarsening during the late-stage phase separation are responsible for the poor tensile properties. It is believed that the composition, the annealing time and the processing temperatures all contribute to the morphology evolution and the consequent mechanical properties of iPP/PEOc blends, furthermore, the crystallization procedure is another crucial factor influencing the ultimate mechanical properties of the investigated blends.