In situ synthesis and characterization of polypropylene/polyvinyl acetate‐organophilic montmorillonite nanocomposite

A novel polymer‐nanoclay hybrid nanocomposite based on polyvinyl acetate (PVAc)‐organophilic montmorillonite (OMMT) has been reported via an in situ intercalated polymerization technique. The hybrid material was synthesized by one‐step emulsion polymerization of vinyl acetate in the presence of OMMT using polyvinyl alcohol as the stabilizing agent. The intercalated polymerization was characterized by X‐ray diffraction (XRD). The XRD patterns show that the interlayer spacing of OMMT after polymerization increased from 2.64 to 3.78 nm, indicating that the large macromolecular chain of PVAc was formed in the OMMT interlayer space. The Fourier transform infrared spectrum showed the characteristic absorption of PVAc in the OMMT particles separated from the nanocomposite, and the position of peaks shifted to high wave numbers. This showed that there was an interaction between PVAc and OMMT nanoparticles. A two‐fold blend composed of PVAc‐nano‐OMMT/PP was prepared by the melt‐blending technique. XRD and transmission electron microscopy images of the PVAc‐nano‐OMMT/PP composite further confirmed the formation of a partially delaminated nanocomposite structure. Thermogravimetry results showed that the thermal stability of PVAc‐nano‐OMMT/PP was greater than that of either polypropylene (PP) or Nano‐OMMT/PP blend. PVAc‐nano‐OMMT/PP had better toughness, as the mass fraction of OMMT was 5 wt %. The flame retardancy of PP, Nano‐OMMT/PP, and PVAc‐nano‐OMMT/PP composites was also studied. According to the limiting oxygen index (LOI) data and Cone calorimeter test, the addition of PVAc‐OMMT resulted in higher LOI and lower heat release rate, effective heat of combustion, smoke release course, and better flame retardancy and barrier properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

高流动性PP／POE／纳米CaCO3复合材料的研制

利用双螺杆挤出机，通过熔融共混工艺制备了聚丙烯(PP)／聚烯烃热塑性弹性体(POE)／纳米CaCO3复合材料。利用扫描电子显微镜(SEM)观察了不同体系的形态，结果显示：纳米CaCO3和POE在PP／POE／nano-CaCO3中互相促进分布及均化。冲击试验结果表明：PP／POE／nano-CaCO3体系的缺口冲击强度较PP／POE、PP／nano-CaCO3和纯PP分别提高了65％，107％和178％。熔体流动速率测试显示：纳米CaCO3在PP／POE／nano-CaCO3中具有提高体系流动性的作用。     

Preparation of nano poly(phenylsilsesquioxane) spheres(nano‐PPSQ) and study of the thermal stability and crystallization behavior of PP/nano‐PPSQ composites

The preparation of nano poly(phenylsilsesquioxane) particles (nano‐PPSQ) and the influence of nano‐PPSQ on the thermal stability and crystallization of polypropylene (PP) were studied. The morphology and thermal stability of PP/nano‐PPSQ composites were characterized by scanning electron microscopy (SEM) and the thermogravimetric analysis (TGA). The SEM result showed that the particles were well dispersed in the PP matrix. The TGA results of the PP/nano‐PPSQ composites indicated that the incorporation of nano‐PPSQ can improve the thermal stability of PP. The crystallization behavior and kinetics of PP/nano‐PPSQ composite were studied by X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). The XRD revealed that the addition of nano‐PPSQ influences the crystallinity and crystal size of PP. The Avrami, Ozawa, and combined Avrami/Ozawa (Mo method) equations were applied to describe the crystallization kinetics and estimate the kinetic parameters of mathematical models under the nonisothermal crystallization of PP and PP/nano‐PPSQ composites. The results show that nano‐PPSQ influences the crystallization temperature and rate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Novel high-strength montmorillonite/polyvinyl alcohol composite film enhanced by chitin nanowhiskers

Nanomaterials can be used as reinforcement phase to improve the performance of polymers. A simple method to prepare a composite film with super high tensile strength was used in this study. The properties of montmorillonite (MMT)/polyvinyl alcohol (PVA) films reinforced by chitin nanowhisker (CNW) have been evaluated. The structures and properties of films were analyzed by atomic force microscope (AFM), Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile testing. The results of FTIR and XRD showed that no chemical interaction occurred among MMT, PVA, and CNW. The SEM and AFM images suggested that the obtained composite films with the three substances had a relatively uniform layered structure and relatively smooth. The temperature at the onset of decomposition of the composite films was increased from 262.0 to 282.3°C by the addition of CNW. The tensile strength of the MMT/PVA/CNW film was reached 263.5 MPa, which was increased approximately 382% compared with the MMT/PVA film. According to these results, the composite film could be potentially used in packaging materials.     

SMA-纳米SiC及SMA-纳米金刚石复合膜制备及其Cu2+离子吸附性能

以纳米SiC及纳米金刚石粉体为添加剂,通过苯乙烯与顺丁烯二酸酐的聚合,成功制备了苯乙烯-马来酸酐-纳米碳化硅(SMA-纳米SiC)及苯乙烯-马来酸酐-纳米金刚石(SMA-nano diamond)复合薄膜材料。通过热重分析(TG)、傅里叶红外光谱仪(FTIR)和扫描电子显微镜(SEM)对吸附复合膜的结构进行表征。研究了SMA-纳米SiC及SMA-纳米金刚石复合膜的吸水性及其对二价铜(Cu²⁺)离子的吸附特性。结果表明,无机纳米颗粒的添加均提高了复合薄膜的耐热特性,提高了热分解温度。当纳米粉体含量在0.8~1.2 g之间,可以获得较为均匀的泡沫状多孔复合薄膜。浸泡6 h,纳米SiC添加量为1.0 g的复合膜吸水率低至4.81%。纳米金刚石添加量为1.0 g,复合膜吸水率低至3.52%。适量的纳米SiC及纳米金刚石可以提高复合膜的耐水性能。SMA-纳米SiC及SMA-纳米金刚石复合膜材料均对Cu²⁺离子具有一定的吸附特性,泡沫状复合膜吸附性能最佳。纳米SiC及纳米金刚石能够有效改善SMA膜对重金属离子的吸附性能。     

Using PA6 as a charring agent in intumescent polypropylene formulations based on carboxylated polypropylene compatibilizer and nano‐montmorillonite synergistic agent

The intumescent fire retardant polypropylene (IFP/PP) filled with ammonium polyphosphate (APP), melamine (M), and PA6 (charring agent) is discussed. Intumescing degree (ID) and the char yield were determined. Only when the three main components of IFR coexist at appropriate proportions, it has optimal ID and higher char yield. The appropriate proportion is PA6 : APP : M = 10 : 10 : 5. A new compatibilizer, carboxylated polypropylene (EPP), was added to PP/PA‐6 blend. Flow tests indicated that the apparent viscosity increased with the addition of EPP, thermal characterization suggested that EPP has reacted with PA6, PA6‐g‐EPP cocrystallized with PA6, and EPP‐g‐PA6 cocrystallized with PP; SEM micrographs illustrated that the presence of EPP improved the compatibility of PP and PA6. All the investigations showed that EPP was an excellent compatibilizer, and it was a true coupling agent for PP/PA6 blends. Using PA6 as a charring agent resulted in the IFR/PP dripping, which deteriorated the flammability properties. The addition of nano‐montmorillonite (nano‐MMT) as a synergistic agent of IFR enabled to overcome the shortcoming. The tensile test testified that the addition of nano‐MMT enhanced the mechanical strength by 44.3%. SEM showed that nano‐MMT improved the compatibility of the composites. It was concluded that the intumescent system with nano‐MMT was an effective flame retardant in improving combustion properties of polypropylene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 739–746, 2006     

Polypropylene/combinational inorganic filler micro‐/nanocomposites: Synergistic effects of micro‐/nanoscale combinational inorganic fillers on their mechanical properties

Polypropylene (PP) has wide applications in various areas, but its low‐temperature brittleness and low moduli have limited its applications in engineering areas. This article reported micro‐/nanoscale combinational inorganic fillers (CIFs) to reinforce PP‐matrix composites as the first example. The CIFs consisted of plate‐like talc (T), needle‐like wollastonite (W), and nano‐Al₂O₃ (N). The PP/CIFs specimens were fabricated via a process of twin‐screw extrusion and screw‐type injection molding. The mechanical properties and thermal deflection temperature (HDT) of the PP/CIF composites were tested according to the corresponding standards, and the morphologies of the tensile‐fractured sections were observed using FE‐SEM. The PP/WT composites had higher mechanical properties and HDTs than those of either PP/W or PP/T. Small amounts of Al₂O₃ nanocrystals together with WT simultaneously strengthened and toughened the PP‐matrix composites. The PP/WTN composite with 2.6% of nano‐Al₂O₃ had well‐balanced properties, enhanced by a large increment when compared with the PP matrix or PP/WT composites. The enhancements should be attributed to the synergistic effects of the CIFs not only in the aspect of various shapes (plate‐like, needle‐like, and spherical) but also in hierarchical size‐levels (microscale and nanoscale). The novel strategy overcame the limitation of conventional rigid modification and solved the problem of uniform dispersion of nanocrystals in polymer matrices. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Improving the flame retardancy of polypropylene by nano metal–organic frameworks and bioethanol coproduct

In this work, a novel flame retardant system based on nano zeolitic imidazolate framework‐8 (ZIF‐8) and the distiller's dried grains with solubles (DDGS) without traditional flame retardants has been designed and blended with polypropylene (PP) to prepare the green flame retarded composites. The influences of nano ZIF‐8 and DDGS on mechanical properties and flame retardancy of PP are studied. The results indicate that combination of nano ZIF‐8 and DDGS improves the mechanical properties of PP, and the tensile strength of the composites containing 29 wt% of DDGS and 1 wt% of nano ZIF‐8 reaches 34.0 MPa compared with 24.7 MPa of pure PP. The limiting oxygen index (LOI) of the composites containing 27 wt% DDGS and 3 wt% of nano ZIF‐8 is about 25.0% compared with 17.5% of pure PP. Besides, its horizontal burning velocity also decreases significantly. The char residues after burning of the PP composites are analyzed, and the mechanism is discussed in detail.     

Enhanced Electrically Conductive Polypropylene/Nano Carbon Black Composite

In this work, a porous polypropylene (PP)/nano carbon black (CB) composite was facilely fabricated via immiscible co-continuous polymer blend and subsequent dissolution process. The porous structure was generated from co-continuous polymer blend, which was exploited as the substrate for depositing nano CB. The interconnected micro pores of the co-continuous polymer blend and nano pores derived from agglomerated CB resulted in a significant enhancement of conductivity. Comparing with the conventional carbon composite obtained through dual-percolation method, the electrical conductivity of PP/CB composite increased 10 orders of magnitude with CB loading ranged from 1 wt% to 5 wt%. Moreover, it was found that the percolation threshold of PP/CB composite decreased nearly 80% compared with that of as-mixed sample. The enhanced conductivity and much lower percolation make this novel method a potential way for fabricating porous conductive materials for advanced application.     

PP/纳米Al_2O_3复合材料及其发泡材料的制备与表征

用PP与纳米Al_2O_3熔融共混法制备复合材料,再用超临界CO_2间歇发泡法制备发泡材料,并对材料的结晶行为、力学性能、发泡行为和导热性能进行研究。结果表明,纳米Al_2O_3能提高复合材料的结晶和熔融温度,但会降低PP链段运动能力,当纳米Al_2O_3含量为7%时,复合材料的结晶度由纯PP的28.10%降至24.46%;纳米Al_2O_3具有刚性粒子的增强增韧协同效果,当纳米Al_2O_3含量为5%时,纳米Al_2O_3的骨架效应使得复合材料的拉伸强度达到33.9 MPa,继续提高其含量后复合材料的拉伸强度略微下降。由于纳米Al_2O_3的刚性粒子增韧效果,当纳米Al_2O_3含量达到7%时,复合材料的冲击强度可达到5.26 k J/m2。纳米Al_2O_3起到异相泡孔成核剂作用,加入5%的纳米Al_2O_3后,发泡材料的泡孔密度提高至2.18×107个/cm3,其热导率在纳米Al_2O_3含量为7%时达到0.107 W/(m·K)。     

聚合物/粘土纳米复合材料及其特殊阻燃性能

介绍聚合物 /粘土纳米复合材料 (PCN)的特殊阻燃性能。通过插层复合法制备了PCN ,研究了PCN的阻燃性能 ,结果表明 ,粘土含量比仅为 2 %和 5 %的尼龙 -6/粘土纳米复合材料的热释放速率峰值比尼龙 -6分别下降 3 2 %和63 % ,烟气的生成速率表现出同—趋势。纳米分散的粘土复合材料的阻燃性与宏观或微米分散的复合材料不同 ,将改性粘土直接加到PP中 ,使体系的氧指数降低 ,添加量较大     

Optical and mechanical properties of transparent acrylic based polyurethane nano Silica composite coatings

The aim of this work is to investigate the effect of two types of nano Silica (precipitated and fumed) with various concentrations on the optical and mechanical properties of transparent polyurethane acrylic based nano composite coatings. Transparency, gloss, UV absorption, adhesion strength and impact resistance of the samples have been measured. The gloss of the film samples remains unchanged compared to the reference film sample up to 2 wt.% (weight percent) for both types of nanoparticles. The samples containing 4 and 6 wt.% nano Silica show reduction in the gloss property by 4.3% and 5.3%, respectively, for fumed samples and 1.8% and 23% for precipitated samples. The film samples show increase in light absorption in the wavelength region of 250–2000 nm by increasing the content of nano Silica. Also cross cut and pull-off test results show that a good adhesion to steel can be obtained (5B for cross-cut, 7 MPa for pull-off) and no changes in impact strength of the samples with respect to the reference have been observed.     

Kinetics of thermal degradation of nanometer calcium carbonate/linear low‐density polyethylene nanocomposites

To improve the thermal properties of linear low‐density polyethylene (LLDPE), the CaCO₃/LLDPE nanocomposites were prepared from nanometer calcium carbonate (nano‐CaCO₃) and LLDPE by melt‐blending method. A series of testing methods such as thermogravimetry analysis (TGA), differential thermogravimetry analysis, Kim‐Park method, and Flynn‐Wall‐Ozawa method were used to characterize the thermal property of CaCO₃/LLDPE nanocomposites. The results showed that the CaCO₃/LLDPE nanocomposites have only one‐stage thermal degradation process. The initial thermal degradation temperature T₀ increasing with nano‐CaDO₃ content, and stability of LLDPE change better. The thermal degradation activation energy (E_a) is different for different nano‐CaCO₃ content. When the mass fraction of nano‐CaCO₃ in nanocomposites is up to 10 wt %, the nanocomposite has the highest thermal degradation E_a, which is higher (28 kJ/mol) than pure LLDPE. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Lubrication of poly(vinyl alcohol) chain orientation by carbon nano‐chips in composite tapes

The extraordinary structural properties of graphene and carbon nanotube materials motivate the development of practical methods for their use in fabricating continuous, strong, and tough composite fibers. Poly(vinyl alcohol) (PVA)/carbon nano‐chip fiber (CNCF) composite tapes with 0.5 wt % loading show that Young's modulus, tensile strength, and toughness are increased by 585%, 653%, and 20%, respectively as compared to the control (PVA) tapes. Nano‐chips exfoliated from the CNCF during processing, lubricate polymer chain alignment, and orientation during drawing, where composite tapes could be drawn to higher draw ratios compared with the control tapes. As a result, the Herman's orientation factor (f) increased from 0.5 (control tape) to 0.8 (composite tape). Theoretical analysis shows ～ 16 vol % of the composite tapes consists of fully oriented PVA chains, which contributes to its exceptional mechanical performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The Relationship between Microstructure and Properties in PP/Rubber Powder/nano‐CaCO3 Ternary Blends

Summary: A new kind of rubber powder with “salami” structure (RPS) was prepared by spray drying the mixture of styrene‐butadiene rubber latex and nano‐CaCO₃ slurry. It was found that RPS is an effective toughener with synergistic toughening effect on poly(propylene) (PP). The Izod impact strength of PP/RPS blend is not only higher than that of PP/rubber powder or PP/nano‐CaCO₃ blends, but also higher than that of a PP/rubber powder/CaCO₃ blend. TEM images show that the microstructure of the PP/RPS blend is an “island‐sea” structure with “salami” structure in RPS, in which nano‐CaCO₃ particles are embedded in styrene‐butadiene rubber particles. The relationship between properties and microstructure has been studied by using TEM, SEM, DSC, etc.

     

Mechanical,thermal, and rheological properties of graphene‐based polypropylene nanocomposites prepared by melt mixing

In this article, we describe the fabrication by melt mixing of graphene‐polypropylene nanocomposites and present the effect of graphene addition on some selected properties of polypropylene (PP). The graphene nanosheets (GNs) used as nano‐reinforcing agents were obtained through chemical reduction of graphene oxide by hydrazine hydrate. GNs were characterized and successfully dispersed into PP matrix to produce PP/GNs nanocomposites. The effects of GNs content on thermal, mechanical, and rheological properties were reported, and the obtained results were discussed in terms of morphology and state of dispersion and distribution of the GNs within the polymer matrix. Characterization by scanning electron microscopy and X‐ray diffraction of the nanocomposites has shown a relatively good dispersion of GNs in the polymer matrix, with the presence of only few aggregates. Increasing GNs content resulted in a significant increase in both mechanical and thermal properties with only few percent of GNs loading. Rheological behavior of the PP/GNs nanocomposites showed a Maxwellian‐like behavior for low GNs concentrations and a viscoelastic solid‐like behavior for GNs content exceeding the concentration of the percolation threshold. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

PP/纳米TiO2复合材料的性能与结构

利用熔融共混的方法制备了PP/纳米TiO2复合材料,研究了纳米TiO2的表面处理和含量对PP/TiO2复合材料力学性能的影响规律,并通过DSC测试方法对复合材料的结构进行分析,合理地解释纳米TiO2对复合材料的影响规律。     

有机磷改性纳米SiO2及其在PP中的应用

用三氯氧磷和异辛醇对纳米二氧化硅(SiO2)进行表面改性,并采用双螺杆挤出机制备了聚丙烯(PP)/表面改性纳米SiO2复合材料。采用傅里叶变换红外光谱仪、差示扫描量热仪、万能材料试验机等研究了表面改性SiO2和复合材料的性能。结果表明,有机磷改性后 SiO2粒子的表面没有羟基,有机磷的接枝率为1.6 %,粒度分布于4～50 μm之间,并且有良好的疏水性,复合材料的断面较规整,熔点与PP基本一致;复合材料在失重的各个阶段对应的温度均比PP高7～10 ℃;改性纳米SiO2能够改善PP复合材料的热稳定性和阻燃性能。     

纳米SiO2/聚丙烯酸酯复合乳液的合成和性能

以过硫酸铵 NH3.H2O为引发体系,通过静电作用成功制成纳米SiO2/聚丙烯酸酯复合乳液。与全丙乳液的性能相比,复合乳液的耐水性、耐热性、耐钙离子性,力学性能都有不同程度的提高,如吸水性下降30.96%,断裂伸长率提高83.3%;紫外线照射500h后,全丙胶膜的拉伸强度和断裂伸长率下降22.34%和26.67%,而复合乳液仅拉伸强度下降5.54%,断裂伸长率并未下降;仪器分析证明复合乳液中存在纳米级别的二氧化硅。     

不同粒径氧化锌以及改性纳米氧化锌对多功能PBAT复合膜的影响

采用溶剂铸膜法制备了聚己二酸/对苯二甲酸丁二酯（PBAT）/聚乳酸（PLA）/对苯二甲酸二辛酯（DOTP）/氧化锌（ZnO）复合膜材料,并通过硬脂酸改性纳米ZnO,探讨了不同粒径ZnO以及改性纳米ZnO对复合薄膜力学性能、热性能、疏水性能、耐抽出性能以及抗菌性能的影响。结果表明,通过硬脂酸代替纳米ZnO表面的羟基极性基团,复合膜的耐抽出性能提高。硬脂酸的长链烷基与高分子链的链纠缠改善了改性纳米ZnO与PBAT的相容性。随着ZnO粒径的减小以及改性纳米ZnO含量的增大,复合薄膜的热性能有所下降,但耐抽出性能提高。拉伸强度提高,最高达到13.8 MPa。复合膜的疏水性能得到改善,接触角最高达到110°,复合膜材料的抑菌区域增大,抗菌性能有所增强。