PREFERENTIAL INTERCALATION BEHAVIOR OF CLAY AND ITS EFFECT ON THE THERMAL DEGRADATION IN IMMISCIBLE PP/PS BLENDS

The typical immiscible PP/PS blend based clay nanocomposites were prepared via melt blending.The dispersion of clay was determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM).Thermal stability and dynamic mechanical properties were measured by thermogravimetrical analysis (TGA) and dynamic mechanical analysis (DMA),respectively.Preferential intercalation behavior of clay in PP/PS blends was found.The dispersion of clay is significantly influenced by the polarity of PP and PS,mea...     

New polyamide - based blends

Among polyamide based blends, PA/PP alloys show interesting technological properties due to low moisture absorption. A model class of PA6/PP homopolymer blends, compatibilized through the addition of PP-g-MA is described in the present work; the experimentally obtained morphologies are related to predictive equations for co-continuity, at given rheological conditions. PP/compatibilizer ratio = 4/1 is found to impart an optimum level of phase dispersion. Moisture absorption, dimensional stability, mechanical properties and morphology are related with blend composition.     

Mechanical and flame‐retardant properties and thermal decomposition of vinyl ester resin modified by different phenyl silsesquioxanes

The mechanical properties and fire resistance of vinyl ester resin (VER) composites containing cage‐shaped octaphenyl silsesquioxane (OPS), incompletely cage‐shaped phenyl silsesquioxane (PhT₇POSS), and ladder‐shaped phenyl silsesquioxane (PPSQ) were investigated. The POSS structure and dispersion have a great influence on the mechanical properties, thermal stability, and decomposition process of VER composites. The bending strength at break and modulus of the VER‐POSS composites were enhanced obviously, especially for VER‐PPSQ composite and VER‐OPS composite, respectively. In addition, PhT₇POSS‐based VER composites revealed the lower values of the peak heat release rate, total heat release, and total smoke release in cone calorimetry tests due to the formation of dense carbon/silica protective layers that acted as a barrier to heat and mass transfer. Moreover, the flame‐retardant mechanisms of condensed phase and gas phase were also investigated in detail. These results illustrate VERs modified by OPS, PhT₇POSS, and PPSQ are providing an applicable method to fabricate the composites with excellent flame‐retardant and mechanical properties.     

Properties of immiscible and ethylene-butyl acrylate-glycidyl methacrylate terpolymer compatibilized poly (lactic acid) and polypropylene blends

Poly(lactic acid) (PLA) and polypropylene (PP) blends of various proportions were prepared by melt-compounding. The miscibility, phase morphology, thermal behavior, and mechanical and rheological properties of the blends were investigated. The blends were immiscible systems with two typical morphologies, spherical droplet and co-continuous, and could be obtained at various compositions. Complex viscosity, storage modulus and loss modulus depend on the PP content. Thermal degradation of all blends led to two weight losses, for PLA and PP. The incorporation of PP improved the thermal stability of the blend. The effect of compatibilizer (ethylene-butyl acrylate-glycidyl methacrylate terpolymer, EBA-GMA) on the morphology and mechanical properties of 70/30 w/w PLA/PP blends was investigated. The tensile strength of these blends reached a maximum for 2.5 wt% EBA-GMA, and impact strength increased with increasing EBA-GMA content, suggesting that EBA-GMA is an effective compatibilizer for PLA/PP blends.     

Interfacial effect on photo-oxidation of PP via model blends

The interface in multiphase material plays an important role not only in mechanical properties, but also in aging behavior. This article uses polypropylene/polymethyl methacrylate (PP/PMMA) and polypropylene/polystyrene (PP/PS) blends (PMMA and PS as dispersion phase) as models to investigate the interfacial effect on the photo-oxidative aging of PP. The chemical property and stability of dispersed phase could make big difference on aging behavior of PP. PMMA, with polar functional group at the interface, accelerated the photo-oxidation of PP, while PS, with inert functional group at the interface, had little influence. Both the dispersion phases have little effects on crystallization of PP and the oxygen diffusion. The photo degradation product of PMMA could help to initiate or accelerate aging of PP mainly via free radicals transfer. Grafting reaction happened in the interface and the interfacial cohesion of PP and PMMA enhanced thereby.     

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.     

Evaluation of the SEBS copolymer in the compatibility of PP/ABS blends through mechanical,thermal, thermomechanical properties,and morphology

Polypropylene (PP) blends with acrylonitrile-butadiene-styrene (ABS) were prepared using the styrene-ethylene-butylene-styrene copolymer (SEBS) as a compatibilizing agent. The blends were prepared in a co-rotational twin-screw extruder and injection molded. Torque rheometry, Izod impact strength, tensile strength, heat deflection temperature (HDT), differential scanning calorimetry, thermogravimetry, and scanning electron microscopy properties were investigated. The results showed that there was an increase in the torque of PA6/ABS blends with SEBS addition. The PP/ABS/SEBS (60/25/15%) blend showed significant improvement in impact strength, elongation at break, thermal stability, and HDT compared with neat PP. The elastic modulus and tensile strength have not been significantly reduced. The degree of crystallinity and the crystalline melting temperature increased, indicating a nucleating effect of ABS. The PP/ABS blends compatibilized with 12.5% and 15% SEBS presented morphology with well-distributed fine ABS particles with good interfacial adhesion. As a result, thermal stability has been improved over pure PP and the mechanical properties have been increased, especially impact strength. In general, the addition of the SEBS copolymer as the PP/ABS blend compatibilizer has the advantage of refining the blend's morphology, increasing its toughness and thermal stability, without jeopardizing other PP properties.     

EFFECT OF MOLECULAR WEIGHT OF PDMS ON MORPHOLOGY AND MECHANICAL PROPERTIES OF PP/PDMS BLENDS

A series of polydimethylsiloxane (PDMS) with varied molecular weights (M_w=3×10~6,1×10~6 and 0.5×10~6) were melt blended with PP to investigate the effect of PDMS molecular weight (MW) on the morphology and mechanical properties of PP/PDMS blends.Scanning electron microscopic (SEM) examination showed that the size of PDMS domains was dependent on the MW of PDMS.It was found that the lower the value of PDMS MW,the better dispersion of the PDMS domains in the PP matrix.Tensile and Izod impact tests reveale...     

环氧树脂在热塑性树脂改性中的应用

本文综述了国内外有关利用环氧树脂改性热塑性树脂共混体系研究的最新进展。着重阐述了环氧树脂在热塑性树脂之间的增容作用,如尼龙6(PA6)合金体系,改性聚苯乙烯塑料(ABS)合金体系,以及聚对苯二甲酸丙二醇酯(PTT)合金体系等。同时,介绍了利用环氧树脂的反应活性提高无机填料在聚合物中分散性研究的情况,如二氧化硅纳米粒子在聚醚砜(PES)中,以及滑石粉在聚丙烯(PP)中分散性的提高。最后,简介了环氧树脂改性热塑性树脂提高热塑性树脂物理机械性能方面的研究方向和成果并展望了环氧树脂在热塑性树脂改性研究中的前景。     

Effect of maleic anhydride-grafted ethylene-propylene rubber on the mechanical, rheological and morphological properties of organoclay reinforced polyamide 6/polypropylene nanocomposites

Polyamide 6/polypropylene (PA6/PP = 70/30 parts) blends containing 4 phr (parts per hundred resin) of organophilic modified montmorillonite (organoclay) were compatibilized with maleic anhydride-grafted ethylene-propylene rubber (EPRgMA). The blends were melt compounded in twin screw extruder followed by injection molding. The mechanical properties of PA6/PP nanocomposites were studied by tensile and flexural tests. The microstructure of the nanocomposite were assessed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The dynamic mechanical properties of the PA6/PP blend-based nanocomposites were analyzed by using a dynamic mechanical thermal analyzer (DMTA). The rheological properties were conducted from plate/plate rheometry via dynamic frequency sweep scans. The melt viscosity in a high shear rate region was performed by using a capillary rheometer. The strength and stiffness of the PA6/PP-based nanocomposites were improved significantly with the incorporation of EPRgMA. Adding EPRgMA to the PA6/PP blends resulted in a finer dispersion of the PP phase. TEM and XRD results revealed that the organoclay was dispersed more homogeneously in the presence of EPRgMA, however, mostly in the PA6 phase of the blends. DMTA results showed that EPRgMA worked as an effective compatibilizer. The storage (G′) and loss moduli (G″) assessed by plate/plate rheometry of PA6/PP blends increased with the incorporation of EPRgMA and organoclay. Furthermore, the apparent shear viscosity of the PA6/PP blend increased significantly for the EPRgMA compatibilized PA6/PP/organoclay nanocomposite. This was traced to the formation of an interphase between PA6 and PP (via PA6-g-EPR) and effective intercalation/exfoliation of the organoclay.     

Maleic Anhydride Polyethylene Octene Elastomer Toughened Polyamide 6/Polypropylene Nanocomposites: Mechanical and Morphological Properties

A series of polyamide 6/polypropylene (PA6/PP) blends and nanocomposites containing 4 wt% of organophilic modified montmorillonite (MMT) were designed and prepared by melt compounding followed by injection molding. Maleic anhydride polyethylene octene elastomer (POEgMAH) was used as impact modifier as well as compatibilizer in the blend system. Three weight ratios of PA6/PP blends were prepared i.e. 80:20, 70:30, and 60:40. The mechanical properties of PA6/PP blends and nanocomposite were studied through flexural and impact properties. Scanning electron microscopy (SEM) was used to study the microstructure. The incorporation of 10 wt% POEgMAH into PA6/PP blends significantly increased the toughness with a corresponding reduction in strength and stiffness. However, on further addition of 4 wt% organoclay, the strength and modulus increased but with a sacrifice in impact strength. It was also found that the mechanical properties are a function of blend ratio with 70:30 PA6/PP having the highest impact strength, both for blends and nanocomposites. The morphological study revealed that within the blend ratio studied, the higher the PA6 content, the finer were the POEgMAH particles.     

POSS nanoparticles as a potential compatibilizer for natural rubber/butadiene rubber blends

In this study, it was aimed to investigate octavinyl‐polyhedral oligomeric silsesquioxane (OV‐POSS) incorporation into natural rubber (NR)/butadiene rubber (BR) elastomer blends as a potential compatibilizer. The effects of OV‐POSS loading levels on the thermal, mechanical, morphological, and dynamic‐mechanical properties of elastomer blends were explored. Fourier‐Transform Infrared Spectrometer (FTIR), Temperature Scanning Stress Relaxation (TSSR), and Differential Scanning Calorimetry (DSC) results revealed the conceivable effect of OV‐POSS nanoparticles in the vulcanization through reacting with sulfur and/or elastomers. Scanning Electron Microscope (SEM), X‐Ray Diffraction (XRD), and tensile test measurements supported the improvement of mechanical properties due to homogeneous dispersion at low loading levels. On the other hand, high amount of OV‐POSS incorporation (7 and 10 phr) resulted in a decrease in mechanical properties, owing to the agglomeration of nanoparticles. According to contact angle and Dynamic mechanical analysis (DMA) results, it could be concluded that OV‐POSS nanoparticles were localized at the interface of the elastomers and enabled the compatibilization of immiscible NR/BR blends.     

Thermal and structural studies of polypropylene blended with esterified industrial waste lignin

Microwave-assisted chemical modification of lignin was achieved through esterification using maleic anhydride. Modified lignin (ML) was blended in different proportions up to 25 mass% with polypropylene (PP) using Brabender electronic Plasticorder at 190 °C. The structural and thermal properties of blends were investigated by thermogravometric analysis (TG), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). TG analysis showed increased thermal stability of blends due to antioxidant property of ML, which opposed oxidative degradation of PP. DSC analysis indicted slight depression in a glass transition temperature and melting temperature of blends due to partial miscible blend behavior between PP and ML. All blends showed higher crystallization temperatures and continuously reducing percentage crystallinity with increasing ML proportion in the blends. WAXD analysis indicated that PP crystallized in β polymeric form in addition to α-form in the presence of ML. However, proportion of β-form did not show linear relation with increase in ML proportion, thus ML acts as β nucleating agent in the PP matrix. SEM analysis showed good dispersion/miscibility in PP matrix indicating modification in lignin is useful.     

动态固化聚丙烯/环氧树脂共混物的研究

将动态硫化技术应用于热塑性树脂 热固性树脂体系 ,制备了动态固化聚丙烯 (PP) 环氧树脂共混物 .研究了动态固化PP 环氧树脂共混物中两组分的相容性、力学性能、热性能和动态力学性能 .实验结果表明 ,马来酸酐接枝的聚丙烯 (PP g MAH)作为PP和环氧树脂体系的增容剂 ,使分散相环氧树脂颗粒变细 ,增加了两组分的界面作用力 ,改善了共混物的力学性能 .与PP相比 ,动态固化PP 环氧树脂共混物具有较高的强度和模量 ,含 5 %环氧树脂的共混物拉伸强度和弯曲模量分别提高了 30 %和 5 0 % ,冲击强度增加了 15 % ,但断裂伸长率却明显降低 .继续增加环氧树脂的含量 ,共混物的拉伸强度和弯曲模量增加缓慢 ,冲击强度无明显变化 ,断裂伸长率进一步降低 .动态力学性能分析 (DMTA)表明动态固化PP 环氧树脂共混物是两相结构 ,具有较高的储能模量 (E′)     

IMPROVED PROPERTIES OF METALLOCENE-CATALYZED LINEAR LOW-DENSITY POLYETHYLENE/POLYPROPYLENE BLENDS DURING ULTRASONIC EXTRUSION

Metallocene-catalyzed linear low-density polyethylene/polypropylene （mLLDPE/PP） blends were prepared by ultrasonic extrusion in this work. Their extrusion processing behaviors were estimated by online measured data, such as the die pressure and flow rate. Crystallization and mechanical properties of the blends were also investigated. The results show that the addition of PP improves the processing behaviors of mLLDPE, but has little effect on its mechanical properties. On the other hand, the addition of mLLDPE improves the impact strength of PP, but has little effect on its processing behavior. The processing behaviors and mechanical properties of mLLDPE/PP blends get further improved due to the presence of ultrasonic oscillation during extrusion. Compared with PP-rich blends, the apparent viscosity drop of mLLDPE-rich blends is more sensitive to ultrasonic oscillation. The ultrasonic oscillation affects the crystal nucleation, while barely the other crystalline behaviors of the blends.     

EFFECT OF MOLECULAR WEIGHT OF PDMS ON MORPHOLOGY AND MECHANICAL PROPERTIES OF PP/PDMS BLENDS

 A series of polydimethylsiloxane (PDMS) with varied molecular weights (Mw = 3  106, 1  106 and 0.5  106) were melt blended with PP to investigate the effect of PDMS molecular weight (MW) on the morphology and mechanical properties of PP/PDMS blends. Scanning electron microscopic (SEM) examination showed that the size of PDMS domains was dependent on the MW of PDMS. It was found that the lower the value of PDMS MW, the better dispersion of the PDMS domains in the PP matrix. Tensile and Izod impact tests revealed that the addition of PDMS with lower MW would lead to a more significant increase in impact strength of the blends compared with the blends with higher MW ones, while the influence of the molecular weight on tensile strengths of the blends was relatively small in the MW range studied. Differential scanning calorimetry (DSC) results also showed that the crystallization temperature of PP was increased with decreasing PDMS MW, indicating a better nucleation capability of lower MW of PDMS. Melting flow rate (MFR) measurements indicated that the processibility of PP could be enhanced by adding PDMS, and again the lower MW PDMS resulted in better data. Our work demonstrates that not only the processibility but also the mechanical properties of PP could be enhanced to a more significant degree by using low MW PDMS than the higher ones.     

Solvent sorption effects on the structure and properties of PP/Rodrun blends

Toluene, carbon tetrachloride, and tetrahydrofuran sorption and desorption by polypropylene (PP) and PP/thermotropic liquid crystal polymer (Rodrun) blends with 20 and 40% Rodrun contents were studied as well as the effects of the solvent presence on the structure and mechanical properties. The rate of sorption and desorption and the solvent content at the equilibrium were higher in the blends than in pure PP. This was attributed to microcracking in the PP matrix induced by the presence of Rodrun. Taking into account the very low permeability of Rodrun to the solvents of this work, and the increase in specific volume of the blends as a result of sorption, sorption‐induced additional microcracking, partially in the form of debonding of the dispersed Rodrun phase, is also believed to occur. Plasticization was the main effect on mechanical properties. The partially irreversible effect of sorption on the mechanical properties agrees with the proposed partial debonding and weak solvent resistance of these blends. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1090–1100, 2000     

Metal functionalized POSS as fire retardants in polypropylene

This paper deals with the study of the combustion properties of dimeric and oligomeric Al-and Zn-isobutyl silsesquioxane (POSS)/polypropylene (PP) composites, in comparison with neat PP and PP/octaisobutyl POSS.The presence of Al-POSS leads to a decrease in combustion rate with respect to PP, resulting in a decrease of Heat Release Rate (−43% at 10 wt% POSS loading) as well as reduction in CO and CO₂ production rates, whereas a negative effect on the above parameters is obtained with octaisobutyl POSS. Zn-POSS does not significantly affect the PP combustion behaviour.The effect of Al-POSS is most likely related to its chemical activity, which favours the formation of a moderate amount of char residue, by catalysing secondary reactions in the polymer during combustion.     

The compatibilizing effect of epoxy resin (EP) on polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr) blends

A new method was used to prepare thermoplastic elastomers based on polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr) with improved mechanical properties. An epoxy resin (EP) was used as a compatibilizing agent. The effect of EP on mechanical properties, swelling percentage and morphological characteristics of the blends was investigated with different blend compositions. The results showed that the incorporation of EP has improved the tensile strength, Young's modulus and elongation at break of PP/NBRr-EP blends compared with PP/NBRr blends. The enhancement of tensile properties of PP/NBRr-EP blends is due to the better adhesion between the two phases with the incorporation of EP. This is quite evident by scanning electron microscopy of tensile fractured surfaces. PP/NBRr-EP blend exhibits lower stabilization torque and swelling percentage than PP/NBRr blends. The lower stabilization torque is an indication of better processing characteristics.     

Synthesis and characterization of polyethylene‐g‐polystyrene as the compatibilizer for polypropylene/ Polystyrene blends

Polyethylene‐g‐polystyrene (PE‐g‐PS) was synthesized as a compatibilizer for polypropylene/polystyrene­(PP/PS) blends by the living radical polymerization of styrene with polyethylene‐co‐glycidylmethacrylate (PE‐co‐GMA). The compatibilizer effect of PE‐g‐PS on the morphology and thermal properties of PP/PS blends was investigated. The crystalline temperature of PP in PP/PS blends decreased with increasing PE‐g‐PS contents. Morphologies of PP/PE‐g‐PS/PS blends showed much better dispersion of each domain for higher PE‐g‐PS contents. The molecular weight of PS segment in PP/PE‐g‐PS/PS blend was increased by addition of styrene monomer during the post melt blending process where post living radical polymerization reaction proceeded. Copyright © 2003 John Wiley & Sons, Ltd.