聚丙烯/黏土纳米复合材料结构及流变性能研究

采用固相法对黏土进行插层改性,制备有机黏土,再与聚丙烯熔融共混,成功制备聚丙烯/有机黏土纳米复合材料。XRD和TEM测试均表明:固相法改性黏土可以与聚丙烯形成结构为插层型和剥离型共存的纳米复合材料。利用动态流变仪研究纳米复合材料的加工流变性能,结果显示,有机黏土的加入有效地改善了聚丙烯的加工流变性能。     

Preparation,Morphology and Properties of Waterborne-Polyurethane/Silica

A series of waterborne-polyurethane/silica (WPU/SiO₂) were prepared from isophoronediisocyanate, polyester polyol, dimethylolpropionic acid, tetraethoxysilane and 3-glycidyloxypropyl trimethoxysilane. The WPU/SiO₂ dispersion had narrower particle size distribution than the pure WPU. The mechanical properties of WPU/SiO₂ films were improved than the pure WPU. WPU/SiO₂ films were characterized by FT-IR spectroscopy, SEM, TEM, AFM, XRD and UV-Vis spectroscopy. The results showed that WPU/ SiO₂ hybrid films were found to be smooth morphology, and had good thermal stability and tunable transparence with the silica fraction in the film. Through suitable adjustment of silica content, some thin films have potential applications as the specialty materials.     

Phase Morphology and Mechanical Properties of Rubber-Toughened Polypropylene Nanocomposites: Effect of Elastomer Polarity

The objective of this work was to investigate the effect of elastomer polarity on phase structure and mechanical properties of PP nanocomposites. The nonpolar and polar elastomers studied were polyethylene octene (POE) and polyethylene octene grafted maleic anhydride (POEgMAH), respectively. The results from mechanical studies showed that the POEgMAH-toughened polypropylene nanocomposites have higher Izod impact strength but lower tensile and flexural properties than the unmaleated ones. X-ray diffraction (XRD) was used to characterize the formation of nanocomposites. XRD studies revealed that intercalated rubber-toughened PP nanocomposites (RTPPNC) had been successfully prepared where the macromolecule segments PP were intercalated into the interlayer space of organoclay. XRD also indicated that the incorporation of polar POEgMAH elastomers into PP nanocomposites contribute to a better intercalation effect and formed a more exfoliated combinations structure compared to POE. Scanning electron microscope (SEM) was used for the investigation of the phase morphology and rubber particle size and particle-size distribution. SEM study revealed a two-phase morphology where POE as droplets dispersed finely and uniformly in the PP matrix. The POEgMAH-toughened PP nanocomposites shows a much finer dispersion of elastomer particles than POE-toughened PP nanocomposites.     

混合增容剂对HDPE/sPS共混物形态及性能的影响

分别采用2种组成相近而分子量不同的苯乙烯-乙烯/丁烯-苯乙烯共聚物(SEBS)以及两者的混合物对高密度聚乙烯/间规聚苯乙烯(HDPE/s PS)共混物进行增容改性。通过扫描电镜(SEM)及拉伸实验试验考查了增容剂的分子量及含量对HDPE/s PS共混物形态结构及力学性能的影响。结果表明:两种增容剂都能降低s PS分散相尺寸,使两相界面的粘合力增强。相对较低分子量的SEBS(K1652)能显著提高两相界面粘结性,进而能有效提高共混物的拉伸强度,而较高分子量的SEBS(K1651)能显著改善共混物的韧性。一定比例混合的共聚物作为增容剂在改善共混物性能方面具有协同效应,可以同时提高共混物拉伸强和断裂伸长率,混合增容剂效果优于单一增容剂。HDPE/s PS共混物中加入质量分数4%的K1652和2%的K1651,共混物的综合力学性能最优。     

Effects of Compatibilizers on Morphology and Properties of Polyoxymethylene/Polypropylene Blends

The effects of polypropylene-graft-maleic anhydride compatibilizer on the mechanical thermal and morphological properties of polyoxymethylene/polypropylene blends were investigated. Polyoxymethylene/polypropylene blends with and without polypropylene-graft-maleic anhydride compatibilizer were prepared by an internal mixer. The morphology of polyoxymethylene/polypropylene blends clearly demonstrated a two-phase separation of dispersed phase and the matrix phase and the addition of polypropylene-graft-maleic anhydride changed the morphological characteristics of blends. Polyoxymethylene/polypropylene blends showed the decrease of mechanical properties with increasing of polypropylene content. The addition of polypropylene-graft-maleic anhydride improved Young’s modulus and storage modulus of polyoxymethylene/polypropylene blends. The incorporation of polypropylene improved the degradation temperature of polyoxymethylene.     

Morphology and Mechanical Properties of PLLA and PCL Scaffolds

Human tissue engineering, comprising methods and tools to create implants, is a promising although as yet a very underdeveloped field of research into the regeneration of specific damaged or necrotic tissue. Porous scaffolds play an important role in tissue engineering. The porous cell culture scaffolds in this study were produced through thermally induced phase separation (lyophilization). This technique yields considerable variations in scaffold microstructures (pore size and morphology) as a function of the polymer, solvent and thermal processing. PLLA and PCL were used with chloroform, 1,4-dioxane and water as solvent. We observed a decrease in mechanical properties with increasing pore size in the two polymers under study. However, we found that PLLA, which possesses larger pore sizes than PCL, showed superior mechanical properties, which we explain in terms of crystallinity.     

纤维素纳米纤丝/聚乙烯醇复合材料热性能与力学性能研究

通过溶液浇铸法制备了纤维素纳米纤丝(CNFs)/聚乙烯醇(PVA)复合材料,利用TG、DSC、DMA等方法考察了CNFs对PVA热性能与力学性能的影响。结果表明:CNFs的加入提高了PVA的结晶度与熔点,但随着CNFs含量的增加,由于CNFs与PVA之间存在较强的氢键作用,限制了PVA分子链的运动,使得PVA的熔点与结晶度略有下降;CNFs的加入使得PVA的玻璃化转变温度、拉伸强度与弹性模量提高,添加2%CNFs的PVA复合材料的拉伸强度与弹性模量均达到最大值,分别较纯PVA提升了28.9%与14.1%。     

增容剂对PP/回收PET共混物性能的影响

采用熔融共混的方法,制备了聚丙烯(PP)/回收聚对苯二甲酸乙二酯(r-PET)共混物,研究了增容剂甲基丙烯酸缩水甘油酯接枝聚丙烯(PP-g-GMA)对共混物力学性能、热稳定性的影响。结果表明:增容剂的加入能提高共混物的拉伸强度和拉伸模量;加入增容剂能显著提高共混物的热分解温度,增容剂使r-PET的熔点降低;增容剂对PP的结晶性能影响与熔融温度有关。     

共混条件对HPVC／PP共混物力学性能,形态和流变性能的影响

本文考察了加料方式、共混温度和时间等共混条件对HPVC/PP共混物力学性能、形态和流变性能的影响.对HPVC50/PP50/CPE10共混物采用7种加料方式,对HPVC50/PP50/ABS10共混物采用2种加料方式来分别考察加料方式的影响;采用B加料方式,分别在160、170和180℃共混,考察温度的影响;在B加料方式170℃时分别共混2、5、10、15min,考察共混时间的影响.结果表明,采用CPE预先与HPVC共混后再与PP共混的加料方式,所得共混物具有最佳的综合力学性能,共混物组分分散最细微;共混温度以170℃为宜;共混时间以5min恰当.加料方式也影响共混物的熔体粘度,CPE或ABS先与HPVC共混后再与PP共混的共混物,其η_α高于CPE或ABS先与PP共混后再与HPVC共混的共混物η_α.     

纳米SiO_2/UP复合材料的力学性能和热性能研究

通过熔融共混、模压成型方法,制备了纳米二氧化硅(SiO2)/不饱和聚酯(UP)复合材料,研究了纳米SiO2含量对复合材料的力学性能、动态力学性能和热膨胀性能的影响,采用SEM观察了复合材料的磨损面形貌。结果表明:当纳米SiO2含量为2.5%时,SiO2/UP复合材料的冲击强度和弯曲强度比纯UP分别提高了28.57%、8.43%;当纳米SiO2含量为3.5%时,SiO2/UP复合材料的玻璃化转变温度比纯UP提高了16℃;当纳米SiO2含量为0.5%时,SiO2/UP复合材料的热膨胀系数为41.367×10-6K-1;加入纳米SiO2后,SiO2/UP复合材料的磨损机理主要表现为磨粒磨损和黏着磨损。     

Morphology,Thermal and Mechanical Properties of Biodegradable Poly(butylene succinate)/Poly(butylene adipate-co-terephthalate)/Clay Nanocomposites

Sodium montmorillonite (Na-MMT) was successfully modified by octadecylamine (ODA) through a cation exchange technique that showed by the increased of basal spacing of clay by XRD. The addition of the organoclay into the PBS/PBAT blends produced intercalated-type nanocomposites with improvements in tensile modulus and strength. The highest tensile strength of nanocomposite was observed at 1 wt% of organoclay incorporated. A TGA study showed that the thermal stability of the blend increased after the addition of the organoclay by 1 wt%. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes smoother with presence of organoclay.     

A Comparative Study on Curing Characteristics,Mechanical Properties,Swelling Behavior,Thermal Stability,and Morphology of Feldspar and Silica in SMR L Vulcanizates

Abstract

Comparison studies on effects of feldspar and silica (Vulcasil C) as a filler in (SMR L grade natural rubber) vulcanizates on curing characteristics, mechanical properties, swelling behavior, thermal analysis, and morphology were examined. The incorporation of both fillers increases the scorch time, t ₂, and cure time, t ₉₀, of SMR L vulcanizates. At a similar filler loading, feldspar exhibited longer t ₂ and t ₉₀ but lower values of maximum torque, M_HR, and torque difference, M_HR–M_L than did silica-filled SMR L vulcanizates. For mechanical properties, both fillers were found to be effective in enhancing the tensile strength (up to 10 phr), tensile modulus, and hardness of the vulcanizates. However, feldspar-filled SMR L vulcanizates showed lower values of mechanical properties than did silica-filled SMR L vulcanizates. Swelling measurement indicates that swelling percentages of both fillers-filled SMR L vulcanizates decrease with increasing filler loading whereas silica shows a lower swelling percentage than feldspar-filled SMR L vulcanizates. Scanning electron microscopy (SEM) on fracture surface of tensile samples showed poor filler–matrix adhesion for both fillers with increasing filler loading in the vulcanizates. However, feldspar-filled SMR L vulcanizates showed poorer filler–matrix adhesion than did silica-filled SMR L vulcanizates. Thermogravimetric analysis (TGA) results indicate that the feldspar-filled SMR L vulcanizates have higher thermal stability than do silica-filled SMR L vulcanizates.     

Barrier and Mechanical Properties of Clay-Reinforced Polymeric Nanocomposites

In this work, clay-based nanocomposites films were prepared by addition of clay-Na⁺ natural montmorillonite in pectin and hydroxypropyl methylcellulose (HPMC) matrices. Mechanical (tensile strength, elastic modulus, and elongation) and barrier (Water Vapor Permeability (WVP), and Oxygen permeability (O₂P)) properties were investigated. From results, it was observed that the WVP and O₂P decreased when nanoclay was included into the HPMC and pectin matrix films. Additionally, the incorporation of nanoclay in the films significantly improved the mechanical properties because the reinforcing effect of clay from its high aspect ratio and its enormous surface area. These results are very important in packaging area.     

针状微胶囊Mg(OH)_2/EVA纳米复合材料的制备及性能研究

将自制针状微胶囊纳米氢氧化(镁Mg(OH)2)与乙烯-乙酸乙烯共聚(物EVA)经双螺杆挤出机熔融共混挤出造粒,然后利用注射机制成针状微胶囊Mg(OH)2/EVA纳米复合材料,对其力学性能、热稳定性和流变性能进行了研究。结果表明:纳米Mg(OH)2用量为4%时,复合材料的拉伸强度最大,加工流动性较好;在低温区时,纳米Mg(OH)2含量对复合材料的热稳定性能几乎没有影响,在高温区时,纳米Mg(OH)2的加入使其热稳定性略有提高。     

相容剂用量对PP/PA11共混物力学性能的影响

研究了相容剂PP-g-MAH用量对PP／PA11共混物力学性能的影响。结果显示,当相容剂质量分数为3％时,体系力学性能最好;同时,偏光显微镜及DSC结果也显示,加入相容剂后,分散相PA11在基体材料PP中的分散更均匀,体系的晶粒尺寸减小。     

成核剂对聚丙烯结晶形态和力学性能的影响

研究了聚丙烯(PP)／成核剂共混物的结晶形态及力学性能。结果表明：加入成核剂后，提高PP的结晶温度，加快了结晶速度，使PP球晶细化；成核剂用量在0—0．2份之间时，PP的冲击强度、拉伸强度、硬度、热变形温度均随成核剂用量的增加而提高。     

The Influence of NBR-g-GMA Compatibilizer on the Morphology and Mechanical Properties of Poly (ethylene terephthalate)/Polycarbonate/NBR Ternary Blends

The work aims to study the role of NBR-g-GMA compatibilizer on the morphology and mechanical characteristics of PET/PC/NBR ternary blends. The compatibilizer content and amount of constitutive polymers are changed to correlate morphology development with mechanical properties. Various ternary samples are prepared using a twin-screw extruder whereat weight percent of rubbery dispersed phase (NBR+NBR-g-GMA) is changed. Analyzing the morphology of produced samples and interpretation of mechanical properties corroborated the role of the mentioned factors on the type of morphology and also the size of both individual and composite domains in these sorts of ternary blends. Based on this attempt, the mechanical properties of 50/50 blends of NBR/NBR-g-GMA, showed maximum toughness value compared to pure PET specimen. Also, the results revealed that by increasing the rubber content, the rodlike structures were disappeared; besides, toughness was increased. On the contrary, by increasing PC content, rodlike structures have seen by morphological study; however, core-shell droplets formed in the blend structure caused enhancing the impact strength and reducing Young's modulus. Ultimately, the ternary blend of 63/7/30 of PET/PC/ (NBR+NBR-g-GMA) revealed the best mechanical properties due to proper interaction between the PET matrix and rubbery domains in the presence of reactive compatibilizer.     

Effect of Rubber Content of ABS on Properties of PC/ABS Blends. I. Rheological,Mechanical, and Thermal Properties

ABSTRACT

The effect of rubber content of poly (acrylonitrile butadiene styrene) (ABS) on compatibility and properties of polycarbonate (PC)/ABS blend systems has been investigated. The rheological, mechanical, physical, and thermal properties of PC/ABS blend systems containing ABS of different rubber content were studied. The reduced torque data on Torque Rheocord indicated improved processability of PC by addition of ABS, however, in ABS-rich compositions, higher rubber content reduces the extent of improvement. The tensile strength of PC decreased with addition of ABS to it but PC-rich compositions have a nearly additive response. The deviation form additivity for blends having higher rubber ABS was more pronounced. However, the impact strength of blends having higher rubber ABS were higher than other types and showed a positive deviation from additivity with variation in compositions. The blends containing ABS with lower rubber content showed a single glass-transition temperature (Tg) in differential scanning calorimetry studies (DSC) in the whole composition range indicating miscibility. Although two Tgs, one associated with PC phase and one with ABS phase, were observed for blends containing high rubber ABS, the shift in Tgs with respect to pure component values indicates partial miscibility. The decrease in the extent of shift with increase of ABS in these blends indicates undesirable phase separation due to poor adhesion of higher level of rubber content.     

动态填充注塑成型PP/nano-SiO2复合材料的力学性能与形貌分析

采用动态填充注塑成型(DFIM)制备了聚丙烯/二氧化硅(PP/nano-SiO2)复合材料。结果表明:与传统的注塑成型技术相比,采用DFIM法制备的PP/nano-SiO2复合材料的拉伸强度和冲击强度比纯PP材料和常规注射制备的复合材料有了较大提高;nano-SiO2通过DPIM技术可以更好地分散在PP基质中,形成的团聚较少。DFIM法制备的PP/nano-SiO2复合材料力学性能的提高,主要归因于nano-SiO2颗粒的均匀分布,使球晶的数量急剧增加,球晶的尺寸明显减小,小晶体有助于形成材料裂纹,从而进一步提高材料的力学性能。     

Morphology,rheological and protective properties of epoxy/nano-glassflake systems

The effect of the glassflake nanoparticles on the rheology, morphology and protective properties of epoxy/glassflake nanocomposites has been studied in this work. Mechanical mixing and sonication process were used to incorporate nano-glassflakes (NGF) into the epoxy. Effects of the time and method of mixing on the morphology and dispersion quality of NGF/epoxy were studied by means of scanning electron microscopic (SEM). Results showed that a 30 min mechanical mixing followed by a 30 min sonication is a best mixing process to design nano-scale glassflake composites. The rheological analysis of epoxy pre-polymer/NGF dispersions indicates that an addition of NGF up to 1 wt% forms microstructure and improves the rheological properties. Barrier properties of the epoxy/NGF coated samples were evaluated by electrochemical impedance spectroscopy (EIS) as a function of immersion time in a sodium chloride solution (5 wt%). The experimental results showed that the barrier properties of the epoxy/NGF coating systems improved by an increase of the NGF content up to 0.5 wt%.