The thermal properties of a carbon nanotube‐enriched epoxy: Thermal conductivity,curing, and degradation kinetics

Multiwalled carbon nanotube‐enriched epoxy polymers were prepared by solvent evaporation based on a commercially available epoxy system and functionalized multiwalled carbon nanotubes (COOH–MWCNTs). Three weight ratio configurations (0.05, 0.5, and 1.0 wt %) of COOH–MWCNTs were considered and compared with neat epoxy and ethanol‐treated epoxy to investigate the effects of nano enrichment and processing. Here, the thermal properties of the epoxy polymers, including curing kinetics, thermal conductivity, and degradation kinetics were studied. Introducing the MWCNTs increased the curing activation energy as revealed by differential scanning calorimetry. The final thermal conductivity of the 0.5 and 1.0 wt % MWCNT‐enriched epoxy samples measured by laser flash technique increased by up to 15% compared with the neat material. The activation energy of the degradation process, investigated by thermogravimetric analysis, was found to increase with increasing CNT content, suggesting that the addition of MWCNTs improved the thermal stability of the epoxy polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2722–2733, 2013     

Probing the reinforcing mechanism of graphene and graphene oxide in natural rubber

Natural rubber (NR) containing graphene (GE) and graphene oxide (GO) were prepared by latex mixing. The in situ chemically reduction process in the latex was used to realize the conversion of GO to GE. A noticeable enhancement in tensile strength was achieved for both GO and GE filled NR systems, but GE has a better reinforcing effect than GO. The strain‐induced crystallization was evaluated by synchrotron wide‐angle X‐ray diffraction. Increased crystallinity and special strain amplification effects were observed with the addition of GE. The incorporation of GE produces a faster strain‐induced crystallization rate and a higher crystallinity compared to GO. The entanglement‐bound tube model was used to characterize the chain network structure of composites. It was found that the contribution of entanglement to the conformational constraint increases and the network molecular parameters changes with the addition of GE and GO, while GE has a more evident effect than GO. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A liquid‐like multiwalled carbon nanotube derivative and its epoxy nanocomposites

Multiwall carbon nanotubes (MWCNTs) with liquid‐like behavior at room temperature were prepared with sulfonic acid terminated organosilanes as corona and tertiary amine as canopy. The liquid‐like MWCNT derivative had low viscosity at room temperature (3.89 Pa s at 20°C) and exhibited non‐Newtonian shear‐thinning behavior. The weight fraction of MWCNT in the derivative was 16.72%. The MWCNT derivative showed very good dispersion in organic solvents, such as ethanol and acetone. The liquid‐like MWCNT derivative was incorporated into epoxy matrix to investigate the mechanical performance of the nanocomposites and the distribution of MWCNTs in the matrix. When the liquid‐like MWCNT derivative content was up to 1 wt %, the flexural strength and impact toughness of composites were 12.1 and 124% higher than the pure epoxy matrix, respectively. Transmission electron microscope (TEM) confirmed the very good dispersion of the liquid‐like MWCNT derivative in epoxy matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2217–2224, 2013     

Novel method of dispersion of multiwalled carbon nanotubes in a flexible epoxy matrix

We describe a simple and novel method for dispersing multiwalled carbon nanotubes (MWCNTs) in a flexible epoxy matrix. The MWCNTs were modified with half‐neutralized dicarboxylic acids having different numbers of carbon atoms. The modified MWCNTs were prereacted with epoxy in the presence of triphenylphosphine. The dispersion of the MWCNTs and the enhancement in the tensile properties were found to be better for composites prepared with a solvent. Among the half‐neutralized dicarboxylic acids used, half‐neutralized adipic acid (HNAA) exhibited the best performance. Scanning electron microscopy and transmission electron microscopy studies clearly indicated an improvement in the level of dispersion of the MWCNTs with the addition of the modifier. The good dispersion of the MWCNTs and the resulting improvement in their properties were attributed to the cation–π interactions (the cation of HNAA and the π‐electron clouds of the MWCNTs) between the HNAA and MWCNTs and the chemical bonding of ? COOH groups of HNAA and the epoxy resin. The cation–π interaction and chemical bonding was assessed with Fourier transform infrared spectroscopy and Raman spectroscopy. This approach did not destroy the π–electron clouds of the MWCNTs in contrast to a chemical functionalization strategy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2610–2618, 2013     

Influence of silanized low‐dimensional carbon nanofillers on mechanical,thermomechanical, and crystallization behaviors of poly(L‐lactic acid) composites—A comparative study

Composites were investigated regarding the comparison of multi‐walled carbon nanotubes (MWCNTs) with exfoliated graphene(EG) in poly(L‐lactic acid) (PLLA) and the effect of silane‐treated carbon nanofillers on properties of PLLA composites. Solution blending method was used to prepare PLLA composites at a filler content of 0.5 wt %. Fourier transform infrared spectroscopy and X‐ray photoelectron spectra results indicated the attachment of silane molecules on the surface of these nanofillers. It was found that the addition of these nanofillers greatly enhanced the mechanical, thermomechanical, and crystallization behaviors of PLLA due to the heterogeneous nucleation effect. Moreover, the silane‐treated fillers further enhanced the breaking elongation moderately (although the materials are still brittle), modulus and thermal property of the nanocomposites, without sacrificing the tensile strength, compared with the pristine nanocomposites. On the other hand, composites reinforced with MWCNTs and EG perform almost the same mechanical property. And EG outperformed MWCNTs in thermomechanical properties of composites when being used as the reinforcement of PLLA. Conversely, composites reinforced with MWCNTs showed better crystallization properties than those reinforced with EG. Interestingly, no significant changes were observed for the crystallization properties of PLLA composites when MWCNTs and EG had been treated by silane coupling agent. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1194‐1202, 2013     

Molecular orientation in self-assembled layers of two functionalized fullerenes—Role of bromine atom at the end of alkyl chain

The IR reflection–absorption spectra of Langmuir–Blodgett (LB) layers of the functionalized fullerenes: C₆₀-fused N-methylpyrrolidine-5-(dodecyl)thiophene (1) and C₆₀-fused N-methylpyrrolidine-5-(12-bromododecyl)thiophene (2) were investigated. It was shown that thin films of functionalized fullerenes are ordered and characteristic parts of the molecules are oriented. Their orientation was evaluated with a simple spectroscopic method. It was stated that bromine atom at the end of aliphatic chain of the sample 2 strongly influences the chain orientation. Similarly, the sulphur atom in the thiophene ring causes some bend of its plane.     

聚乙二醇放电介质中洋葱状富勒烯的制备与表面修饰

以分子量为600、400和200的聚乙二醇（PEG）为介质电弧放电法制备了洋葱状富勒烯（OLFs）;利用空气氧化法于450℃条件下对产物进行了提纯,并用含氧射频等离子体对纯化后的OLFs进行了表面氧化修饰;用场发射扫描电镜、高分辨透射电镜、X射线衍射和傅立叶变换红外光谱对所得产物进行了表征和分析。结果表明：在PEG200中放电制得的OLFs粒径均匀,石墨化程度较高;空气氧化法能提高OLFs产物的纯度;当氧气含量为20％时,表面氧化修饰效果明显。     

Soot Formation in Combustion Processes (Review)

A review is given of recent papers on the phenomenology, kinetics, and mechanism of soot formation in hydrocarbon combustion; the effects of various factors on the formation of polycyclic aromatic hydrocarbons, fullerenes, and soot, low-temperature soot formation in cool flames, combustion in electric field, and the paramagnetism of soot particles from an ecological viewpoint are considered. __________ Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 6, pp. 137–156, November–December, 2005.     

Four decades of research in solid state chemistry

Solid state chemistry was in its infancy when the author got interested in the subject. In this article, the author outlines the manner in which the subject has grown over the last four decades, citing representative examples from his own contributions to the different facets of the subject. The various aspects covered include synthesis, structure, defects, phase transitions, transition metal oxides, catalysts, superconductors, metal clusters and fullerenes. In an effort to demonstrate the breadth and vitality of the subject, the author shares his own experiences and aspirations and gives expression to the agony and ecstacy in carrying out experimental research in such a frontier area in India. Distinguished Materials Scientist Award Lecture presented at the MRSI meeting, Trivandrum on February 9, 1993. Professor C N R Rao, born on June 30, 1934 in Bangalore, received the M. Sc. degree in Physical Chemistry from Banaras Hindu University in 1953, the Ph.D degree from Purdue University, USA in 1958 and the D.Sc. degree from the University of Mysore in 1960. He was a research scholar at IIT, Kharagpur (1953–54), Lecturer at the Indian Institute of Science (1959–63), Associate Professor (1963–64) and Professor (1964–76) at the Indian Institute of Technology, Kanpur. He was the first Head of the Chemistry Department as well as the first Dean of Research at IIT, Kanpur. He moved back to the Indian Institute of Science in 1976 where he was founder Chairman of the Solid State and Structural Chemistry Unit and the Materials Research Laboratory till 1984, when he became the Director of the Institute. He has been President of the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore since its founding in 1989. He was President of the Indian National Science Academy and the Indian Academy of Sciences as well as the International Union of Pure and Applied Chemistry. He was Commonwealth Professor at the University of Oxford and Nehru Professor at the University of Cambridge. He is the author of over 800 research papers and has authored/edited 30 books pertaining to solid state chemistry, spectroscopy, molecular structure, surface science and chemical education. He is a member of the editorial boards of over 15 international journals and is the founder-editor of the Bulletin of Materials Science. He is Honorary Professor at the University of Wales, Cardiff (UK) and Adjunct Professor at the Pennsylvania State University. Of the many honours received by Professor Rao, mention may be made of the Marlow Medal of the Faraday Society, London (1967), Bhatnagar Prize (1968), Jawaharlal Nehru Fellowship (1973), Padma Shri (1974), Sir C V Raman Award of the University Grants Commission (1975), Centennial Foreign Fellowship of the American Chemical Society (1976), Federation of the Indian Chambers of Commerce and Industry Prize (1977), S N Bose Medal of the Indian National Science Academy (1980), Royal Society of Chemistry (London) Medal (1981), P C Ray Medal of the Indian Chemical Society (1984), Padma Vibhushan (1985), Nehru Award for Science (1988), Modi Award for innovative science (1989), Hevrovsky Gold Medal of the Czechoslovak Academy (1989), Honorary Fellowship of the Royal Society of Chemistry, London (1989), Meghnad Saha Medal of INSA (1990), CSIR Golden Jubilee Prize in physical sciences (1991), Blackett Lectureship of the Royal Society (1991), K K Barooah Foundation Award for Science (1992) and Goyal Prize in Chemistry (1993). Professor Rao is a Fellow of the Science Academies in India and of the Royal Society, London. He is a Foreign Associate of the US National Academy of Sciences and a Foreign Member of the American Academy of Science and Arts, the Russian Academy of Science as well as the Czech, Polish, Serbian and Slovenian Science Academies. He is a member of the Pontifical Academy of Sciences and a founder fellow of Third World Academy of Sciences (of which he is now Vice President). He is an honorary member of the Materials Research Societies of Japan and South Korea and of the International Academy of Ceramics and honorary fellow of Institution of Engineers and IETE. He has received D.Sc. (honoris Causa) from 22 Universities. He was a member of the first National Committee on Science and Technology and later of the Scientific Advisory Committee to the Union Cabinet. He was Chairman of the Science Advisory Council to Prime Minister Rajiv Gandhi.     

Study of poly(methyl methacrylate) film doped with inclusion complex of p‐tert‐butylcalix[8]arene

Seven kinds of poly(methyl methacrylate) (PMMA) films doped with [60]fullerene or its inclusion complex of p‐tert‐butylcalix[8]arene were prepared and characterized by FTIR, UV‐vis, TG, and DSC. It was found that the thermal stability of PMMA is much improved by doping with the inclusion complex in comparison with [60]fullerene itself, that is, the inclusion complex retards the thermal depolymerization of PMMA very effectively. The influence of incorporating active carbon powder or calix[8]arene on the thermal stability of PMMA was also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1549–1552, 2002