New Millable Polyurethane/Organoclay Nanocomposite: Preparation,Characterization and Properties

The preparation, characterization and properties of novel millable polyurethane/organoclay nanocomposites are reported. Clay treated with methyl tallow bis(2‐hydroxyethyl) quaternary ammonium chloride was used as an organoclay for nanocomposite preparation. X‐ray diffraction indicated the intercalation of polymer chains inside the interlayer spacings of the clay. Dynamic mechanical analysis showed a significant increase in storage modulus, and tensile strength increases with increased organoclay loading.

X‐ray diffraction patterns of millable polyurethane/organoclay nanocomposites.     

Photopolymerization and Characteristics of Polyurethane/Organoclay Nanocomposites

Different polymerizable ammonium surfactants were successfully synthesized via Michael‐addition and quaternarization reactions. Organoclays containing reactive methacrylate groups were prepared by the cationic exchange process. Intercalated nanocomposites were produced by UV initiated polymerization with 5 wt.‐% organophilic clay loading. DMTA tests and tensile analysis implied that a long chain polymerizable modifier could crosslink with the polymer matrix, and mechanical and tensile properties were enhanced dramatically about 80%. Water sorption was not elevated, which was determined by the polymer itself and the hydrophobicity of the modifier, although the water permeation was improved.

     

iPP Based Nanocomposites Filled with Calcium Carbonate Nanoparticles: Structure/Properties Relationships

Isotactic polypropylene (iPP) based nanocomposites filled with calcium carbonate nanoparticles (CaCO₃) were prepared by melt mixing and structure-properties relationships of the nanomaterials were studied. Elongated CaCO₃ nanopowders coated with two different coating agents, polypropylene-maleic anhydride graft copolymer (iPP-g-MA) and fatty acids (FA), were tested as nanoreinforced phases. The influence of surface treatment of the nanoparticles on the polymer/nanofillers interfacial adhesion and on the final materials properties was investigated. Morphological analysis showed that the selected coating agents induce different iPP/nanofiller adhesion degrees. Young's modulus increases as a function of the nanoparticles content and the coating agent nature. Finally, all the prepared nanocomposites showed a significant improvement of iPP barrier properties either to oxygen or to carbon dioxide.     

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.     

聚丙烯/PMMA/CaCO3纳米复合材料的制备、结构与力学性能

分别将经不同表面处理的纳米碳酸钙粒子与聚合物PP共混,制备PP／CaCO3和PP／PMMA／CaCO3纳米复合材料。用TEM观察了表面处理后纳米粒子的粒径与分散情况,发现复合粒子分散较均匀。用DSC与WAXD研究了复合材料的结晶行为,发现原位聚合制备的PMMA／CaCO3纳米复合粒子与PP共混后,PP有异相成核作用,出现了不稳定的PPβ晶型。PP／PMMA／CaCO3纳米复合材料力学性能有大幅度的提高。     

Polymer Nanocomposites from Organoclays: Structure and Properties

Summary: Polymer nanocomposites formed from organically modified montmorillonite offer the promise of greatly improved properties over those of the matrix polymer, provided the organoclay can be dispersed, or exfoliated, into the polymer matrix to generate high aspect ratio particles. The exfoliation of organoclays in two series of ethylene-based polymers, ethylene-vinyl acetate copolymers and sodium ionomers of ethylene-methyacrylic acid copolymers, is described along with the properties of these nanocomposites.     

插层聚合制备聚丙烯/蒙脱土纳米复合材料及其结构性能表征

将插层聚合的概念引入烯烃聚合,制备了聚丙烯／蒙脱土（PP／MMT）纳米复合材料。X射线衍射和TEM分析结果表明,蒙脱土在聚丙烯基体中达到了纳米级的分散,动态力学性能研究结果表明,在高于Tg的温度区域内PP／MMT纳米复合材料的储能模量（E′）成倍增加,加入8％的蒙脱土（MMT）,PP／MMT的E′提高近3倍。PP／MMT的玻璃化转变温度Tg有一定程度的提高,随蒙脱土含量的增加,PP／MMT的热分解温度和热变形温度（HDT）都有大幅度提高。     

Nylon 6/Calcium Carbonate Nanocomposites: Characterization and Properties

Two polymorphic modifications of calcium carbonate nanoparticles (calcite and aragonite) characterized by different shape and coated with fatty acids were used as reinforcement phases of Nylon 6. Nylon 6 based nanocomposites filled with 1% and 5% by weight of calcite and aragonite were prepared by melt mixing. Morphological analysis performed on the fractured surface of nanocomposites showed that the coating agent permits to obtain uniform and fine nanoparticles dispersion. DMTA analysis revealed that nanoparticles increase the glass transition temperature of Nylon 6 up to 12 °C in the case of calcite, while a less pronounced increase was recorded for aragonite. Finally, structural analyses (FT-IR and WAXS) underlined that calcite nanoparticles promote and stabilize the γ-crystalline form of Nylon 6, while in the case of aragonite nanofillers the α-crystalline form was still dominant.     

Barrier and Mechanical Properties of Poly(caprolactone)/organoclay Nanocomposites

In this study, biodegradable poly(caprolactone) (PCL) hybrids with two types of organoclays: Cloisite 30B (30B) and Cloisite 93A (93A) have been prepared by melt mixing and their barrier performance to air permeation and mechanical properties were investigated. The hybrids of PCL/30B were found to be nanocomposites resulted from the strong interaction between organic modifier of 30B and PCL and those of PCL/93A were microcomposites. The barrier performance of PCL/30B nanocomposite film to air permeation was much more improved than pure PCL and PCL/93A microcomposites at low organoclay concentration. With the increase of organoclay content the permeability coefficient was also increased that could attributed to the extra tortuous pathway for gas permeation caused by organoclay exfoliation. The barrier behaviour of PCL/30B nanocomposites could be approximately described by a theoretical model developed for composites. The mechanical properties measurements showed that the reinforcement of organoclay 30B in nanocomposites is more significant than 93A in microcomposites. Both tensile modulus and tensile strength were increased in PCL/30B nanocomposites even at at low amount of organoclay without much loss of strain at break as compared to pure PCL. The significant improvements in both barrier and mechanical properties in PCL nanocomposites could be attributed to the fine dispersion state of organoclay 30B platelets in PCL matrix and the strong interaction between organic modifier of 30B and matrix molecules.     

聚丙烯/层状硅酸盐纳米复合材料的制备、结构和性能

聚丙烯／层状硅酸盐纳米复合材料可通过丙烯单体插层聚合、聚丙烯溶液插层和聚丙烯熔融插层等方法制备，得到插层型或剥离型纳米复合材料，形成了与传统填充型聚合物复合材料不同的微观结构，其机械性能，热性能，阻隔性能和流变性能等明显提高，由于聚丙烯的非极性及层状硅酸盐纳米复合材料制备方法的特殊性，该研究具有一定的理论价值。     

等规聚丙烯/聚丁烯-1釜内合金的结构与性能

高分子材料的组成、 组分分布及链结构与宏观性能紧密相关. 因此, 分析多组分釜内合金材料的链结构特点与性能之间的关系至关重要. 采用升温淋洗分级的方法对两种采用序贯两段聚合原位合成的等规聚丙烯/聚丁烯-1(iPP/iPB)釜内合金在-30 ℃~140 ℃温度范围进行分级, 采用核磁共振波谱仪、 傅里叶变换红外光谱仪、 差示扫描量热仪和凝胶渗透色谱仪等表征了级分的链结构及序列分布、 热行为、 分子量(M_w)及分子量分布(M_w/M_n)等. 结果表明iPP/iPB合金主要由5种级分组成, 高等规聚丁烯(iPB)为主要组分, 同时含有少量的丁烯-丙烯嵌段共聚物(PB-b-PP)和等规聚丙烯(iPP)等. 随淋洗温度升高, PB-b-PP级分中PP嵌段长度逐渐增加, PB嵌段长度逐渐减小; 在相同的淋洗温度, 合金B的嵌段共聚物级分中PP嵌段较长且结晶较完善; 合金B中iPB组分及嵌段共聚物组分含量较高, 使得合金B具有较高的拉伸强度、 弯曲强度、 优异的抗冲击性能、 较高的维卡软化温度及较快的晶型转变速率.     

Diels-Alder反应可控制备交联等规聚丙烯

交联改性可以提升聚合物材料的机械性能、热稳定性及化学稳定性。 含有蒽基团的高质均分子量等规聚丙烯(iPP)可由配位共聚合反应制得,随后通过双官能的马来酰亚胺试剂与iPP中悬挂蒽基团间的Diels-Alder反应可以成功制备交联的iPP膜材料。 材料的交联度可以通过凝胶重量分析及膜红外分析得出,并由制备过程中交联剂的加入量有效地调控。 通过示差扫描量热仪(DSC)与广角X射线衍射仪(WAXD)表征发现,随交联度增加,交联改性限制了分子链的运动,iPP的结晶度逐渐降低、结晶能力逐渐下降。 对交联材料的动态热机械分析仪(DMA)测试表明,随交联度增加,iPP的损耗模量逐渐降低,材料韧性变差。 交联iPP的T_g逐渐升高,说明材料的耐热性得到提升。 由于交联形成了聚合物链间的交联网络,形成了更多受力点并且限制了聚合物链的自由移动,交联材料的拉伸强度随交联度的升高而增加,而断裂伸长率逐渐下降。     

Nanocomposites by melt intercalation based on polycaprolactone and organoclay

Nanocomposites based on biodegradable polycaprolactone (PCL) and organically modified layered silicates (organoclay) were prepared by melt mixing. Their structures and properties were characterized by wide‐angle X‐ray diffraction, thermal analysis, and rheological measurements. The exfoliation of the organoclay was achieved via a melt mixing process in an internal mixer and showed a dependence on the type of organic modifier, the organoclay contents, and the processing temperature. The addition of the organoclay to PCL increased the crystallization temperature of PCL, but a high content of the organoclay could show an inverse effect. The PCL/organoclay nanocomposites showed a significant enhancement in their mechanical properties and thermal stability due to the exfoliation of the organoclay. The nanocomposites showed a much higher complex viscosity than the neat PCL and significant shear‐thinning behavior in the low frequency range. The shear storage modulus and loss modulus of the nanocomposites also exhibited less frequency dependence than the pure PCL in the low frequency range, and this was caused by the strong interactions between the organoclay layers and PCL molecules and by the good dispersion of exfoliated organoclay platelets in the PCL. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 670–678, 2003     

Effect of Organoclay Mixture on the Rheological Properties of ABS-Clay Nanocomposites

Summary: In this work, poly(acrylonitrile-butadiene-styrene) (ABS) and different organically modified montmorillonite clay nanocomposites were prepared by melt intercalation in a co-rotating twin screw extruder. The influence of the screw torque during processing and of the mixture of the modified organoclays in the intercalation/exfoliation of the clay in the polymeric matrix was evaluated through low angle X-ray diffraction range and capillary and parallel plate-plate rheometry.     

Polypropylene Nanocomposites,Study of the Influence of the Nanofiller Nature on Morphology and Material Properties

Summary: In this paper we investigate the influence of various nanofilllers' aspect ratio, chemical nature and organic modification on some selected polypropylene properties, such as crystallinity, thermal and mechanical resistance and fire behaviour. Materials were prepared by twin-screw extrusion and characterized by means of scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, tensile and cone calorimeter tests. Fillers characteristics were found to influence at different extents, and for different reasons, the material final properties.     

Effect of Polyhedral Oligomeric Silsesquioxane and Sorbitol on Properties of Isotactic Polypropylene

Isotactic polypropylene(iPP) was modified by the introduction of polyhedral oligomeric silsesquio- xanes(POSS) and 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol(DMDBS). Chemical combination of (3-mercapto)- propyl-heptaisobutyl POSS with DMDBS(POSS-DMDBS), and physical mixing of DMDBS with octaisobutyl POSS (iso-POSS/DMDBS) or trisilanolisobutyl POSS(tri-POSS/DMDBS) were applied respectively to modifying iPP, and the effects of POSS and DMDBS on crystallization, rheological and mechanical properties of iPP were systematically investigated. The results indicate that iso-POSS/DMDBS and tri-POSS/DMDBS were more effective than POSS-DMDBS on the improvement of the crystallization behavior of iPP due to the higher crystallization temperature, while the crystallinity of iPP containing POSS-DMDBS was enhanced, approximately approached to that of iPP containing tri-POSS/DMDBS. The tensile strength of iPP with POSS-DMDBS was significantly increased from 34 MPa to 40 MPa, as high as that of iPP with iso-POSS/DMDBS. The different effects caused by the specific interaction between POSS and DMDBS could possibly be applied in the modification of iPP.