Rheology and Physical Properties of Polyethylene/Polyethylene‐Ionomer Blends and their Clay Nanocomposites

Rheological and solid‐state physical properties of blends containing high‐density polyethylene (HDPE) and a polyampholyte derivative (PE‐g‐PA) are assessed along with their onium ion‐exchanged montmorillonite clay (NR‐MM) nanocomposites. Strong deviations from the log‐additivity rule of zero‐shear viscosity, combined with synergistic behavior in tensile moduli, are consistent with a multi‐phase blend morphology. While this affects clay dispersion in filled blends, PE‐g‐PA/HDPE based nanocomposites are shown to exhibit a favorable balance between material stiffness and ductility.

     

淀粉／聚乙烯共混物的降解

淀粉和聚乙烯二者极性差别很大，如何提高淀粉／聚乙烯共混物降解塑料中两相的相容性是此项研究的技术关键．采用添加增容剂［１］，或进行淀粉疏水改性［２］，或对聚乙烯进行亲水改性［３］的办法均取得了一定的进展．本文在提高相容性研究的基础上，又添加油酸和有机铁...     

Characterization of HDPE /Polyamide 6/ Nanocomposites Using Scanning-and Transmission Electron Microscopy

Summary: Preparation and morphology of high density polyethylene (HDPE)/ polyamide 6 (PA 6)/modified clay nanocomposites were studied. The ability of PA 6 in dispersing clays was used to prepare modified delaminated clays, which were then mixed with HDPE. Mixing was performed using melt processing in a torque rheometer equipped with roller rotors. After etching the materials with boiling toluene and formic acid at room temperature, the morphology was examined by SEM analyses, showing that the PA 6 formed the continuous phase and HDPE the dispersed phase. X-ray diffraction patterns show that the (001) peak of the clay is dramatically decreased and shifted to lower angles, indicating that intercalated/exfoliated nanocomposites are obtained. TEM analyses confirmed the typical structure of exfoliated nanocomposites. A scheme for the mechanism of exfoliation and/or intercalation of these HDPE /PA 6/ /organoclay nanocomposites is proposed.     

Morphology and Thermal Characteristics of Polyethylene Nanocomposites Made Using Montmorillonite‐Supported Cp2ZrCl2 and Ni‐Diimine Precatalysts

Bis(cyclopentadienyl)‐zirconium dichloride (Cp₂ZrCl₂) and (1,4‐bis(2,6‐diisopropylphenyl)‐acenaphthenediimine) dichloronickel (Ni‐diimine) were supported on montmorillonite (MMT) pretreated with triisobutylaluminum and 10‐undecence‐1‐ol to produce in situ polyethylene–clay nanocomposites in a gas‐phase reactor. The development of the nanocomposite morphology was investigated with transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis. During polymerization, the MMT layers were partially exfoliated by the growing polymer chains, starting from the openings of the clay galleries, but intercalation and exfoliation occurred only to a certain extent. The thermal properties of the nanocomposites we also analyzed by differential scanning calorimetry (DSC).

     

The Dynamic Viscoelasticity of Polyethylene Based Montmorillonite Intercalated Nanocomposites

The viscoelastic behavior of melts for two systems composed of intercalated nanocomposites based on low density polyethylene and 3 wt% loading of cetyltrimethylammonium bromide modified montmorillonite was studied. The results obtained through examining the dynamic storage module G‘ and dynamic loss module G“ values of the composite revealed that the dynamic viscoelastic properties of composite strongly depended on intercalation of polymer, and exhibited dramatically change with altering intercalation conditions. Only when modified montmorillonite content was about 3 wt%, the composite showed a trend of pseudo-solidlike at lower frequencies.     

Observation of Regime III Crystallization in Polyethylene/Montmorillonite Nanocomposites

Summary: Exfoliated and intercalated polyethylene/montmorillonite (PE/MMT) nanocomposites with high MMT content were prepared by in situ polymerization. The isothermal crystallization kinetics of the nanocomposites were analyzed with Lauritzen–Hoffman regime theory. Regime III crystallization, which is difficult to observe in linear polyethylene, appears in the PE/MMT nanocomposites. The broader temperature range of regime III crystallization in PE/MMT nanocomposites shows that the mobility and reptation ability of the PE chains are greatly reduced by the MMT, especially in the intercalated nanocomposite.

Plots of ln K/n + U*/R(T_c − T₀) against 1/T_c(ΔT)f for the intercalated and exfoliated PE/MMT nanocomposites.     

高密度聚乙烯/蒙脱土纳米复合材料膨胀阻燃体系的性能

使用以乙烯/醋酸乙烯共聚物(EVA)为相容剂的高密度聚乙烯/蒙脱土(HDPE/OMT)纳米复合材料作为基体,制备了含不同成炭剂的聚磷酸铵(APP)膨胀阻燃体系,对其阻燃性能进行了比较和研究,并分析了蒙脱土与膨胀阻燃剂协效作用的机理。热重分析(TGA)、垂直燃烧(UL-94)、极限氧指数(LOI)、锥形量热计结果表明:APP/季戊四醇(PER)体系熔融过程较短可形成蒙脱土增强炭层;PER/PA/OMT体系中较高的有机物含量有利于蒙脱土迁移和堆积。     

Rheological Behavior and Wear Abrasion Resistance of Polyethylene Oxide/Laponite Nanocomposites

Polymer/layered silicate nanocomposite thin films were developed as clear, transparent coatings. Laponite‐S, which is a synthetic layered clay, was dispersed in a polyethylene oxide matrix and solution cast onto glass slides for further testing. Rheological properties, wear abrasion resistance, and scratch resistance were tested for each sample to examine the nanoparticle dispersion effects on the materials' properties. In this study, we identify and characterize the materials to be used, establish the appropriate conditions for the preparation of polymer/Laponite nanocomposite dispersions, illustrate methods for the development of PEO/Laponite‐S films, and characterize the films. Results on the rheological behavior of PEO‐silicate nanocomposites as a function of Laponite solids loading and PEO concentration, as well as some preliminary wear abrasion properties of the films are presented in this study.     

Polyethylene-Montmorillonite Nanocomposites: Preparation,Characterization and Properties

Polyethylene(PE)/clay nanocomposites have been successfully prepared by in situ polymerization with an intercalation catalyst titanium-montmorillonite (Ti-MMT) and analyzed by X-ray diffraction analysis (XRD), Fourier transform infrared analysis (FT-IR), Transmission electron microscopy (TEM), differentail scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and tensile testing. XRD and TEM indicate that the clay is exfoliated into nanometer size and disorderedly dispersed in the PE matrix, and the PE crystallinity of PE/clay nanocomposite declines to 15∼30%. Compared with pure PE, PE/clay nanocomposites behave higher thermal, physical and mechanical properties; the layer structure of the clay decreases the polymerization activity and produce polymer with a high molecular weight. For PE/clay nanocomposites, the highest tensile strength of 33.4 MPa and Young's modulus of 477.4 MPa has been achieved when clay content is 7.7 wt %. The maximum thermal decomposition temperature is up to 110 °C higher, but the thermal decomposition temperature of the PE/clay nanocomposites decreases with the increases of the clay contents in the PE matrix.     

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.     

固相法氯化聚乙烯对PVC／LLDPE共混体系性能和形态的影响

采用固相法氯化聚乙烯（ＣＰＥ）对聚氯乙烯／线型低密度聚乙烯（ＰＶＣ／ＬＬＤＰＥ）共混体系进行增容改性。扫描电子显微镜、透射电子显微镜、动态力学分析和力学性能测试结果表明，ＣＰＥ对ＰＶＣ／ＬＬＤＰＥ共混体系具有很好的增容作用。     

线性低密度聚乙烯／乙烯醋酸乙烯共聚物共混体系的相容性及性能

线性低密度聚乙烯／乙烯醋酸乙烯共聚物共混体系的相容性及性能杨毓华＊白春霞花荣于李三喜（中国科学院长春应用化学研究所长春１３００２２）（沈阳化工学院高分子科学与工程系沈阳）关键词线性低密度聚乙烯，乙烯醋酸乙烯共聚物，共混，相容性，ＤＳＣ，ＷＡＸＤ，力...     

Heat Shrinkable Behavior and Mechanical Response of a Low‐Density Polyethylene/Millable Polyurethane/Organoclay Ternary Nanocomposite

Summary: A low‐density polyethylene (LDPE)/millable polyurethane (PU)/organoclay ternary nanocomposite was successfully prepared. The nanocomposites were characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The nanocomposites, as evidenced by XRD, are intercalated. The heat shrinkable behavior of the nanocomposites, as well as their pristine counterparts, was studied. It was observed that heat shrinkability decreases with increased filler content. The tensile strength and the tensile modulus of the nanocomposites are higher than their pristine counterparts.

The heat shrinkability of the unfilled LDPE/millable PU blend is highest and it decreases with increased nanofiller content.     

Synthesis of Novolac/Layered Silicate Nanocomposites by Reaction Exfoliation Using Acid‐Modified Montmorillonite

Novolac/layered silicate nanocomposites were synthesized by condensation polymerization of phenol and formaldehyde catalyzed by H‐montmorillonite (H‐MMT). Exfoliation of the clay was investigated by X‐ray diffraction and transmission electron microscopy (TEM). It turned out that the intra‐gallery condensation of phenol and formaldehyde played a predominant role in the exfoliation of MMT. Exfoliated clay plates with interlayer spacings of 10–30 nm were dispersed in the matrix uniformly as shown by the TEM micrograph.     

固相法氯化聚乙烯增韧聚氯乙烯的研究

研究了聚氯乙烯与固相法氯化聚乙烯的相容性与氯含量、共混方式以及ＣＰＥ链结构的关系，动态力学性能表明ＰＶＣ／ＣＰＥ为部分相容体系，ＣＰＥ中类似ＰＶＣ的链段与ＰＶＣ形成相间过渡层，共混方式影响共混体系的相容程度，透射电镜结构表明ＣＰＥ呈连续网络结构分布于ＰＶＣ粒子表面，共混条件一定时，共混物的抗张强度随相容性的改改善而增加。     

增容聚苯乙烯共混物的研究进展

综述了增容聚苯乙烯与聚乙烯、聚丙烯、聚酰胺共混物的研究进展。不同共混物采用不同的增容剂,可使增容聚苯乙烯共混物改善分散相尺寸、界面相互作用与粘结,达到提高共混物的力学性能的目的。增容效果与增容剂的类型、用量和分子结构有关。     

Polyethylene and Poly(propylene)/Clay Nanocomposites

Polyethylene and polypropylene nanocomposites were investigated with focus on mechanical and barrier properties. Structure was observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Four types of nano-filler were used: Nanofil 5, 8, 9 and 3000. In case of polyethylene nanocomposites the dispersion and intercalation was to low extent. Mechanical and barrier properties were worse compared to pure PE. In case of polypropylene with Nanofil 5, 9 and 3000 tensile strength was better compared to pure PP. Also PP with Nanofil 9 and 3000 had better barrier properties than pure PP for both O₂ and CO₂. This was explained by better intercalation and dispersion of the filler documented by XRD measurement and TEM observation.     

Reorientational Dynamics of Polyethylene Glycol/PAMAM Dendrimer Blends

The reorientational dynamics of dipoles in a series of blends of Polyethylene Glycol (PEG) and poly(amidoamine) (PAMAM) dendrimers were investigated by broadband dielectric relaxation spectroscopy (DRS). Measurements were performed over a wide range of frequency and temperature. Neat PEG exhibits three relaxation processes: the segmental process in the amorphous phase and two faster processes due to the localized motions in the amorphous regions and the rotation of hydroxyl end groups. Addition of dendrimers to the PEG matrix slows down the segmental process in the amorphous phase, but has no effect on the relaxation time of local processes in PEG. However, H-bonding which forms between the PEG oxygen and the amino groups on dendrimer surface is responsible for a shift of local processes in dendrimers to lower frequency. A detail analysis of the effect of temperature, concentration of dendrimers and molecular weight of PEG on the relaxation dynamics is offered.