有机蒙脱土改性超支化聚酰胺6的制备与表征

以枝化剂为超支化聚酰胺6（PA6）的引发剂,配以含有端羧基官能团的有机改性剂改性的有机蒙脱土（O-MMT）,经原位开环接枝聚合制备了O-MMT/超支化PA6复合材料。通过FTIR和TEM表征了超支化PA6与O-MMT的接枝情况以及O-MMT在基体中的分散形态。研究了O-MMT对超支化PA6结晶性能、熔体流动性能和力学性能的影响。结果表明:O-MMT呈剥离态和插层态分散于超支化PA6基体中,且与PA6分子链段产生化学键合,形成网络交联结构。网络交联结构使O-MMT/超支化PA6复合材料与超支化PA6相比熔体流动指数急剧下降。另外,O-MMT使超支化PA6的α晶型消失,且使仅有γ晶型的超支化PA6的结晶度降低。但随O-MMT 含量增加,O-MMT/超支化PA6复合材料的强度逐步提高,拉伸强度从38.4 MPa提高至60.8 MPa。复合材料的韧性也得到大幅度提高,断裂伸长率从2.1%提高至70.1%,无缺口冲击强度从20.3 kJ/m2急剧提高至291.8 kJ/m2。      

Modification of montmorillonite by novel geminal benzimidazolium surfactant and its use for the preparation of polymer organoclay nanocomposites

A new benzimidazolium derivative, the benzimidazolium-N,N′-hexadecane-2-hydroxy-ethyl bromide (Bz) featuring two geminal hexadecyl hydrophobic buttress has been synthesized and used for the functionalization of sodium montmorillonite (MMT-Na) via cationic exchange process. The resulting benzimidazolium-modified MMT (MMT-Bz) exhibits a large d-spacing of 3 nm between silicate layers and shows a high thermal stability compared to the commonly used clay modified alkyl ammonium salts (cloisite 20A and cloisite 20B). MMT-Bz was incorporated in high density polyethylene (HDPE) matrix via melt mixing method to produce HDPE/MMT-Bz nanocomposites. The microstructure and the morphology of these nanocomposites were studied by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The dispersion state of the organoclay within HDPE was monitored by UV–Vis spectroscopy and melt rheology. A more homogeneous dispersion or a greater content of the MMT-Bz in the matrix produced stronger solid-like and non-terminal behavior in the nanocomposites. Tensile properties and thermal stability were evaluated and discussed on the basis of the amount of clay incorporated within the nanocomposites. The intercalated structure in the nanocomposites, resulting from both the better dispersion/distribution of clay nano-platelets and their strong interaction with the polymer chains, provides the driving force to significantly enhance the HDPE properties.     

氧化镁填料的表面辐射接枝改性

本文采用共辐照方法将甲基丙烯酸甲酯(MMA)接枝到氧化镁MgO)粉末填料上,用傅里叶红外光谱和X射线衍射对接枝物进行了表征,并利用ESCA、SEM以及接触角测定对其表面性质进行了研究。将接枝改性后的MgO作为高密度聚乙烯(HDPE)的填料,实验结果表明,表面改性后的MgO在聚合物基质中的分散性得到明显改善,填入改性MgO的HDPE其断裂强度和断裂伸长率均有明显提高,且热稳定性也得到了显著的提高。     

Ultrasound assisted synthesis of PMMA/clay nanocomposites: Study of oxygen permeation and flame retardant properties

PMMA/clay nanocomposites were synthesized by ultrasound assisted emulsifier-free emulsion polymerization technique. Ultrasound waves of different power and frequencies were applied to enhance the dispersion of the clay layers with polymer matrix. The structural information of the synthesized materials was studied by X-ray diffraction (XRD) and it was revealed that the interlayer spacing increased with clay loading. The magnitude of dispersion of the clay in the polymer matrix was detected by transmission electron microscopy (TEM). The Young’s modulus, breaking stress, elongation at break, toughness, yield stress and yield strain of the nanocomposites as a function of different clay concentrations and ultrasonic power were measured. Particle diameter of the nanocomposites was measured by laser diffraction technique. Oxygen permeability of the samples was studied and it was found that the oxygen flow rate was reduced by the combined effect of clay loading and ultrasound. The flame retardant property of the nanocomposites due to clay dispersion was investigated by measurement of limiting oxygen index (LOI).     

Thermal and thermomechanical properties of poly(butylene succinate) nanocomposites

This article describes the thermal and thermomechanical properties of poly(butylene succinate) (PBS) and its nanocomposites. PBS nanocomposites with three different weight ratios of organically modified synthetic fluorine mica (OMSFM) have been prepared by melt-mixing in a batch mixer at 140 degrees C. The structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD) analyses and transmission electron microscopy (TEM) observations that reveal the homogeneous dispersion of the intercalated silicate layers into the PBS matrix. The thermal properties of pure PBS and the nanocomposite samples were studied by both conventional and temperature modulated differential scanning calorimetry (DSC) analyses, which show multiple melting behavior of the PBS matrix. The investigation of the thermomechanical properties was performed by dynamic mechanical analysis. Results reveal significant improvement in the storage modulus of neat PBS upon addition of OMSFM. The tensile modulus of neat PBS is also increased substantially with the addition of OMSFM, however, the strength at yield and elongation at break of neat PBS systematically decreases with the loading of OMSFM. The thermal stability of the nanocomposites compared to that of the pure polymer sample was examined under both pyrolytic and thermo-oxidative environments. It is shown that the thermal stability of PBS is increased moderately in the presence of 3 wt% of OMSFM, but there is no significant effect on further silicate loading in the oxidative environment. In the nitrogen environment, however, the thermal stability systematically decreases with increasing clay loading.     

Polybutene as a matrix for wood plastic composites

This study examined the feasibility of using polybutene-1 (PB-1), a ductile plastic, as a matrix for manufacturing wood plastic composites (WPCs) with improved toughness and ductility compared to currently commercialized WPCs. The processability, tensile, flexural, and impact properties of injection molded PB-1/wood-flour composite samples with varying proportions of wood flour were characterized. Analysis also included the morphology of fractured samples surface and adhesion between the polymer and wood flour using SEM. Comparisons of the mechanical properties and adhesion in the PB-1 composites to those of HDPE and PP-based WPCs found the composites made with PB-1 matrix significantly inferior in strength and stiffness (both in tensile and flexural) than their counterparts made of HDPE and PP matrices. In contrast, the processability, elongation at break, impact strength and adhesion in PB-1/wood-flour composites, superior to those of HDPE and PP, confirmed their suitability for use as a matrix in composites intended for applications subjected to high impacts.     

Electrical and mechanical properties of expanded graphite/high density polyethylene nanocomposites

High density polyethylene (HDPE) were filled with expanded graphite particles that have different particle sizes, 5–7 μm (EG5) and 40–55 μm (EG50) in diameter. Nanocomposites were prepared by the melt-mixing technique using EG5 and EG50 at different weight ratios. Transmission Electron Microscopy (TEM) was used to observe the morphology of the nanocomposites. X-ray diffraction patterns of EG5-HDPE and EG50-HDPE nanocomposites were investigated. Tensile tests were carried out to determine tensile strength, Young’s modulus and elongation at break values. The storage modulus and loss modulus were evaluated by Dynamic Mechanical Analysis (DMA). The effect of EG5 and EG50 on electrical conductivity of HDPE was also determined. The tensile strength of HDPE increased 18.7% and 8.5% when 40 wt% EG5 and EG50 was added into HDPE, respectively. The storage modulus of EG5-HDPE and EG50-HDPE is higher compared to that of HDPE. Incorporation of EG5 and EG10 into HDPE also increased the relaxation transition peak of HDPE. The values of electrical conductivity for EG50-HDPE nanocomposites under the same filler content obtained higher in comparison with those for EG5-HDPE nanocomposites.     

Effect of Multi-Wall Carbon Nanotubes on the Mechanical Properties of Natural Rubber

Multi-walled carbon nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first efforts to achieve nanostructures in MWNTs/NR nanocomposites were formed by incorporating carbon nanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubes can be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, elongation at break and hardness were studied. Mechanical test results show an increase in the initial modulus for up to 12 times in relation to pure NR. In addition to mechanical testing, the dispersion state of the MWNTs into NR studied by Transmission Electron Microscopy (TEM) in order to understand the morphology of the resulting system     

PC改性HDPE共混体系的组成对拉伸性能的影响

本工作旨在通过共混改性实现聚烯烃塑料高性能化。介绍了高密度聚乙烯／聚碳酸酯共混体系中组成对拉伸性能及形态的影响。结果表明，随ＰＣ含量增加，共混物的拉伸强度增加，断裂伸长率降低，而加入１０ｐｈｒ的增容剂烯基双酚Ａ醚接枝ＬＤＰＥ的体系，在相同ＰＣ含量时，其拉伸强度和断裂伸长率均高于未加增容剂的体系；ＰＣ含量低时，体系中ＰＣ基本上呈圆球状，ＰＣ含量较高时，部分ＰＣ粒子为形成椭球状、长条状，甚至纤维状；共     

Study on mechanical and ablative properties of EPDM/OMMT thermal insulating nanocomposites

In order to enhance the elongation at break, the ablation resistant properties as well as the tensile strength of the thermal insulating materials, organo-montmorillonite (OMMT) was introduced into the short aramid fibers reinforced Ethylene-Propylene-Diene Monomer (EPDM) based nanocomposites. The effects of OMMT content on the mechanical and ablative properties of the nanocomposites were investigated systematically. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirm that EPDM-matrix has been intercalated into OMMT interlayers after a mixing process on a two-roll mill. The brittle fracture of nanocomposites also indicates that OMMT can lubricate aramid fiber to weaken the interfacial adhesive strength between the fibers and the matrix. As a result, the tensile strength and elongation at break are both improved sharply with OMMT content increasing from 1 phr to 7 phr. However, thanks to the inevitable agglomeration of OMMT with high loading inside the nanocomposites, the tensile strength and elongation at break reduce gently once OMMT is over 7 phr. Furthermore, the ablation resistant properties are improved greatly by increasing OMMT from 1 phr to 11 phr. Therefore, the optimal content of OMMT is 7-11 phr for the thermal insulating nanocomposites with big elongation and excellent ablation resistant properties.     

An Investigation on Vibration Welding of Amorphous and Semicrystalline Polymers

Vibration welding technique has been used to study the weld zone of thermoplastic polymers using ABS (amorphous), PC (amorphous), PMMA (amorphous), and PBT (semicrystalline). Polymers were welded using alike components and combinations of semicrystalline polymer with different amorphous polymers. Mechanical testing of welded polymers has proved that the tensile strength, elongation at break, and deformation was highest for PC–PC weld and least for ABS–ABS weld, when alike polymers were welded. However, welding of semicrystalline and amorphous polymer shows enormous reduction in its tensile strength as well as other tensile properties. Also, the tensile fracture of PBT with other amorphous polymers always occurred at weld zone which was not always in case of alike polymer welds. The weld strength of these polymers was observed to be dependent on the mechanical interlocking among the layers and not on interfacial bonding. This phenomenon may be due to the difference in glass transition temperatures of semicrystalline and amorphous polymers. XRD, FESEM, and AFM have been used in this study to observe the morphology of welded surfaces.     

Effect of nanoclay and SEBS-g-MA on the morphology and properties of immiscible poly(methyl methacrylate)/polystyrene blend

In recent years, nanoclays are being used as compatibilizer for various immiscible polymer blends. However, little work has been done on the morphology of immiscible polymer blends in presence of both the nanoclay and a reactive compatibilizer. Here, we report the synergistic effect of nanoclay and SEBS-g-MA on the morphology and properties of (70/30 w/w) PMMA/PS blend. Scanning electron microscopy study of the blend with various amount of nanoclay and SEBS-g-MA indicated a reduction in the average domain sizes (D) of dispersed PS phase in PMMA matrix compared to that in the pure blend. Addition of both SEBS-g-MA and nanoclay significantly lowered the D of PS in the blend compared to that with only SEBS-g-MA or clay. X-ray diffraction study and transmission electron microscopy revealed the presence of intercalated clay platelets in PMMA matrix, as well as, at the interface of the (70/30 w/w) PMMA/PS blend-clay nanocomposites. Addition of SEBS-g-MA in the blend-clay nanocomposites promoted the exfoliation of clays in PMMA matrix. Thus, exfoliated clay platelets in PMMA matrix effectively restricted the coalescence of dispersed PS domains while SEBS-g-MA improved the adhesion between the phases at the interface. At certain loading (phr), storage modulus, elongation at break and thermal stability of the blend were greatly improved when both the nanoclay and SEBS-g-MA were present in the blend. The use of reactive compatibilizer and nanoclay in polymer blends may lead to a high performance material which combines the advantages of compatibilized polymer blends and the merits of polymer nanocomposites.     

Structure and mechanical properties of polycarbonate modified clay nanocomposites

Polycarbonate (PC)/modified clay nanocomposites were prepared, in the absence and presence of different amounts of maleic anhydride grafted polypropylene (PP-g-MA), by direct melt blending. Their structures, as well as mechanical, morphological and thermal properties, were characterized by X-ray diffractometry (XRD), tensile testing, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The XRD results of the PC/clay nanocomposites showed that they had intercalated structures, although some exfoliation was visible at low clay contents, that the gallery heights of the PC/clay nanocomposites were almost the same, and that some of the clay layers collapsed as a result of modifier decomposition at the high processing temperature. The XRD patterns of the PC/PP-g-MA/clay nanocomposites clearly show less intercalation and more exfoliation with increasing PP-g-MA content. These results were supported by TEM observations. Both the tensile strength and modulus show substantial improvements with both increasing clay and PP-g-MA contents, while the elongation at break substantially decreases, although the presence of PP-g-MA somewhat improves these values. All the nanocomposites have lower thermal stability than pure PC, but the presence of PP-g-MA seems to improve the thermal stability of these samples.     

植酸-金属离子螯合物改性层状黏土及其在聚己内酯中的增强与抗菌效应研究

基于植酸(PA)优异的螯合能力,利用Ag^+,Cu^2+,Fe^3+和Zn^2+4种金属离子与PA发生螯合作用并沉积吸附在层状双羟基复合金属氧化物(LDHs)表面,形成核-壳结构,以达到改善层状黏土与聚合物基体之间界面相容性的目的。制备出不同金属离子负载的表面包覆改性LDHs(LDHs@PA-M),深入研究LDHs@PA-M在不同金属离子负载下的微观形貌,并将其应用在聚己内酯(PCL)的增强改性中。结果表明,PA能够与Ag^+和Cu^2+在LDHs表面形成稳定、均匀的纳米包覆层。利用金属Ag^+和Cu^2+优异的抗菌活性,LDHs@PA-Ag^+和LDHs@PA-Cu^2+对大肠杆菌(E.coli)的抗菌率均超过99.99%。相比于纯的PCL,LDHs@PA-Cu^2+/PCL纳米复合材料(LDHs@PA-Cu^2+的质量分数为1%)的拉伸强度和断裂伸长率分别提高了30.7%和33.3%,达到了40.9 MPa和816%,力学性能增强效果最为显著。LDHs@PA-Cu^2+/PCL和LDHs@PA-Ag^+/PCL纳米复合材料对E.coli的抗菌率均达到99.99%,表现出优异的抗菌活性,拓展了层状黏土/生物基高分子复合材料在活性包装领域的应用。     

Effect of multi-wall carbon nanotubes on the mechanical properties of natural rubber

Multi-walled carbon nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first effort to achieve nanostructures in MWNTs/NR nanocomposites were formed by incorporating carbonnanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubess can be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, tear strength, elongation at break and hardness were studied. Mechanical test results show an increase in the initial modulus for up to 12 times in relation to pure NR. In addition to mechanical testing, the dispersion state of the MWNTs into NR was studied by transmission electron microscopy (TEM) in order to understand the morphology of the resulting system. According to the present study, application of the physical and mechanical properties of carbon nanotubes to NR can result in rubber products which have improved mechanical, physical and chemical properties, compared with existing rubber products reinforced with carbon black or silicone.     

Preparation and characterisation of polyamide 11/montmorillonite (MMT) nanocomposites for use in angioplasty balloon applications

With increased demands on catheter balloon functionality, there is an emphasis to blend new materials which can improve mechanical performance. Polymer nanocomposites were prepared by melt blending polyamide 11 (PA 11) with organically modified montmorillonite nanoclay. The effects of incorporating the nanoclay on the short-term mechanical properties of PA 11 were assessed using a design of experiments (DoEs) approach. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis techniques (DMA) were used to characterise the morphology of the nanocomposites. Design of experiments studies revealed that the optimum nanocomposites properties can be achieved by carefully controlling the melt compounding parameters. XRD and TEM data proved that exfoliated clay morphologies existed within the matrix at low clay loading (2%). Whereas the interaction between the polymer matrix and nanoclay was quantified in the DMA spectra, showed a significant increase in storage modulus (up to 80%). The reinforcing effect of nanoclay within the PA 11 was further investigated using mechanical testing, where significant increases in the ultimate tensile strength and strain at break of reinforced tri-layer balloon tubing were observed.     

Preparation and properties of nitrile rubber/montmorillonite nanocomposites via latex blending

The nitrile rubber (NBR)/unmodified montmorillonite (Na-MMT) clay nanocomposites were prepared by latex blending method followed by melt mixing of compounding ingredients by using two-roll mill. The X-ray diffraction (XRD) studies showed an increase in the basal spacing and broadening of peak corresponding to crystal structure of Na-MMT indicating the formation of intercalated/exfoliated clay layers in the NBR matrix. Increase in clay content of nanocomposite increased the XRD peak height due to the formation of many of clay tactoids at higher loading. The transmission electron microscopy (TEM) strengthened the XRD finding by showing the presence of intercalated/exfoliated morphology of clay platelets having good dispersion. The modulus and tensile properties of the nanocomposites were improved with addition of Na-MMT which is proportional to clay concentration. The retention of tensile properties of aged nanocomposites, with all clay concentration, was superior to either pure NBR and carbon black filled NBR composite. The dynamic mechanical analysis showed proportional increase in storage modulus analogous to Na-MMT loading at all the temperature ranges due to the confinement of polymer chains between the clay layers. Nanocomposites with different proportions of clay showed a decrease in tan δ_max peak height with a shift towards higher temperature indicating the reduction in the segmental mobility of polymer chain. A linear model was proposed to correlate the influence of Na-MMT content on storage modulus of nanocomposites. Differential scanning calorimetry indicated a linear increase in glass transition of nanocomposites which is proportional to clay loading. Thermogravimetric analysis revealed a small improvement in the thermal stability of nitrile rubber/clay nanocomposites.     

Preparation and characterization of poly(methyl methacrylate)-clay nanocomposites via melt intercalation: Effect of organoclay on thermal, mechanical and flammability properties

The PMMA nanocomposites were prepared by melt processing method. The influence of organoclay loading on extent of intercalation, thermal, mechanical and flammability properties of poly(methyl methacrylate) (PMMA)-clay nanocomposites were studied. Three different organoclay modifiers with varying hydrophobicity (single tallow vs. ditallow) were investigated. The nanocomposites were characterized by using wide angle X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The intercalation of polymer chain within the silicate galleries was confirmed by WAXD and TEM. Mechanical properties such as tensile modulus (E), tensile strength, percentage elongation at break and impact strength were determined for nanocomposites at various clay loadings. Overall thermal stability of nanocomposites increased by 16-17 °C. The enhancement in T_g of nanocomposite is merely by 2-4 °C. The incorporation of maleic anhydride as compatibilizer further enhanced all the properties indicating improved interface between PMMA and clay. The flammability characteristics were studied by determining the rate of burning and LOI.     

Processing and thermal,mechanical and morphological characterization of post-consumer polyolefins/thermoplastic starch blends

Mixtures of high density polyethylene (HDPE) and polypropylene (PP), both post-consumer polymers were blended with thermoplastic starch (TPS). Corn starch plastification was carried out by extrusion with glycerin addition. The behaviour of TPS produced was investigated in the processing and thermal, mechanical and morphology characterization of post-consumer HDPE/PP blends (100/0, 75/25, and 0/100 wt.%) in different proportions of TPS (30%, 40% and 50% wt.%) by melting flow index (MFI), tensile property measurements, and scanning electron microscopy (SEM), respectively. The addition of TPS reduced the MFI of PP and increased of HDPE and HDPE/PP blends. TPS also decreased the tensile strength and elongation at break, and increased the rigidity of the materials. SEM showed separation of phase between the poliolefins and TPS.     

Fabrication and characterization of elastomeric polyester/carbon nanotubes nanocomposites for biomedical application

A novel biodegradable polymer elastomer nanocomposite composing of poly(1,8-octanediol-citrate) (POC) polymer matrix and carbon nanotubes (CNTs) additive was successfully fabricated and systematically investigated using Fourier transform infrared (FT-IR), X-ray diffractometer (XRD), differential scanning calorimetry (DSC), tensile test, incubation and cytotoxicity tests. It was found that the addition of CNTs in POC elastomer did not result in any noticeable change in its chemical structure and the amorphous state. However, the tensile strength and elongation at break were greatly improved by the addition of CNTs in POC polymer matrix. It revealed that the swelling ratio and percentage of weight loss of POC/CNTs nanocomposite were lower, compared with the pure POC material. Moreover, the adsorption amount of bovine serum albumin (BSA) increased with an increase of the CNTs mass content in POC matrix revealing the enhanced hydrophilicity of POC/CNTs nanocomposites contributed by the carboxyl of the CNTs. Additionally, the cytotoxicity tests with L929 cell line revealed that the experimental POC/CNTs nanocomposites possessed good in vitro biocompatibility.