Papers by Author: Ming Qiu Zhang

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Authors: Jim Lee, Debes Bhattacharyya, Ming Qiu Zhang, Yiu Wing Mai, Yan Chao Yuan
Abstract: The concept of introducing self-healing capabilities in polymer materials and systems has been based on mimicking biological self-healing materials and systems, for example, materials like proteins have phenomenal capabilities in self-healing damaged biological structures. This work has been extended to investigate self-healing capabilities of fibre reinforced epoxy composites. Microencapsulated epoxy and mercaptan healing agents were incorporated into a glass fibre reinforced epoxy matrix to produce a polymer composite capable of self-healing. The specimens containing the microencapsulated epoxy and mercaptan healing agents did gain excellent strength and achieved a healing efficiency up to 140%.
Authors: Ming Qiu Zhang, Min Zhi Rong, Shi Guo Chen
Abstract: The present work synthesized conductive composites consisting of waterborne polyurethane (WPU) and carbon black (CB). Besides the low percolation threshold (0.70.95wt%), the composites are quite sensitive to organic solvent vapors regardless of their polarities as characterized by the drastic changes in conductivity. In the case of polar solvents, negative and positive vapor coefficient phenomena of the composites were successively observed with a rise in CB content. It was found that different mechanisms are responsible for the broad applicability of the composites as candidates for gas sensing materials owing to the different interactions among the matrix polymer, the filler particles and the solvent molecules.
Authors: Wen Hong Ruan, Min Zhi Rong, Ming Qiu Zhang
Abstract: To prepare polymer nanocomposites with enhanced performance, well dispersion of nanoparticles in matrices is necessary. In this work a new route that combines graft pre-treatment and drawing technique with melt mixing was applied. That is, nano-SiO2 particles were firstly modified by graft polymerization and then the grafted nanoparticles were melt-compounded with polypropylene (PP) producing composites filaments via drawing. Finally, the filaments were injection molded into bulk materials. The resultant PP based nanocomposites are much tougher than the unfilled polymer as characterized by either static or dynamic test, besides showing a simultaneous increase in strength and stiffness. Morphology studies indicated that drawing induced extension and separation of the grafted nano-silica agglomerates in PP matrix during making the filaments are frozen to a certain extent after nanocomposites manufacturing. In this way, the nanoparticles are well distributed in the matrix and correlated with each other throughout the entire composites, which might ensure an overall improvement of mechanical properties. Besides, β-crystal of PP developed in the drawing process can be retained in the nanocomposites, which also contributes to the toughening of PP. In view of these, the proposed drawing aided dispersion of nanoparticles might also be applicable to the preparation of other nanoparticles/polymer composites.
Authors: Min Zhi Rong, Ming Qiu Zhang, Su Ping Wu, Hong Juan Wang, Tibor Czigány
Abstract: In this work, plastic foams were prepared from plant oil resins based on soybean oil and castor oil. Firstly, epoxidized soybean oil (ESO) reacted with acrylic acid using N, N-dimethyl benzyl amine as the catalyst, and castor oil was modified with maleic anhydride, respectively. Acid number was used to monitor the reaction process, and structures of the resultant acrylated epoxidized soybean oil (AESO) and maleate castor oil (MACO) were proved by Fourier Transform Infrared (FTIR) measurements. It was found that the catalyst is quite effective in synthesizing AESO. Then, plastic foams based on AESO and MACO were synthesized through free radical initiated copolymerization with diluent monomers including styrene and methyl methacrylate. Mechanical properties, reinforcing effect of sisal fiber and biodegradable feature of the foams were characterized, showing the suitability of the bio-foams for acting as packaging materials.
Authors: Li Feng Cai, Min Zhi Rong, Ming Qiu Zhang, Wen Hong Ruan
Abstract: To promote dispersion of nano-silica in polypropylene (PP), a polymerizable foaming agent p-vinylphenylsulfonylhydrazide was synthesized and grafted onto the nanoparticles via free-radical polymerization. The results of thermogravimetric analysis (TGA) showed that the sulfonyl hydrazide groups of poly(p-vinylphenylsulfonylhydrazide) acquired the desired thermal decomposition ability, which might be related to their internal oxidation-reduction. Electron microscopy observation indicated that the grafted nanoparticles exhibit greatly improved dispersion in PP owing to the fact that the sulfonyl hydrazine groups on the grafted polymer inside the agglomerates decomposed like blowing agent to form polymer bubbles, leading to rapid inflation of the surrounding matrix that pulled apart the agglomerated nanoparticles during melting mixing.
Authors: Tong Hui Zhou, Wen Hong Ruan, Min Zhi Rong, Ming Qiu Zhang
Abstract: In our previous works, a double percolation mechanism of stress volumes was proposed to explain the special effects generated by small amounts of grafted nanoparticles. Accordingly, it is inferred that strengthening nanoparticle agglomerates and enhancing nanoparticles/polymer matrix interfacial interaction are the key issues to improve mechanical performance of the matrix polymer. To confirm this idea, in-situ crosslinking was adopted to prepare nanocomposites by adding reactive monomers and crosslinking agents during melt compounding of nano-silica with polypropylene (PP). It was found that the grafted polymer chains were successfully crosslinked and chemically bonded to the nano-silica forming crosslinked networks. Meanwhile, matrix molecular chains penetrated through the networks to establish the so-called semi-IPN structure that interconnected nanoparticles by the networks and improved filler/matrix interfacial interaction. As a result, the tiny nanoparticles were well distributed in the matrix and the toughening and reinforcing effects of the nanoparticles on the matrix were brought into play at rather low filler loading, as evidenced by mechanical performance tests. Besides, β-crystal was detected in the nanocomposites experienced in-situ crosslinking reaction.
Authors: Hai Ping Wang, Yan Chao Yuan, Min Zhi Rong, Ming Qiu Zhang
Abstract: For purposes of developing a novel self-healing chemistry for polymer composites, melamine-formaldehyde (MF) resin-walled microcapsules containing styrene were prepared by in-situ polymerization in an oil-in-water emulsion. Chemical structure of the microcapsules was identified by Fourier-transform infrared spectroscopy (FTIR) and proton magnetic resonance spectroscopy (1H NMR), respectively. In addition, scanning electron microscope (SEM) and optical microscope (OM) were used to investigate morphology and geometry of the product. The effects of dispersion rate, weight ratio of core to shell and emulsifier concentration were carefully analyzed. It was found that poly(melamine-formaldehyde) (PMF) microcapsules containing styrene were successfully synthesized through the proposed technical route, and their mean diameters fall in the range of 20~71 µm. The rough surface of the microcapsules is composed of agglomerated PMF nanoparticles. Both core content and size of the microcapsule can be adjusted by selecting different processing parameters. The highest loading of styrene in the capsules is about 60% and the emulsifier with lower molecular weight used to result in higher core content. In terms of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), thermal behavior and storage stability of the capsules were studied. The results indicated that the microcapsules can be handled up to 72 oC.
Authors: Min Zhi Rong, Su Ping Wu, Ming Qiu Zhang
Abstract: In this work, a simple but effective approach was reported for preparing natural fiber reinforced plastic foams based on plant oil with excellent compressive performance and biodegradability. Firstly, epoxidized soybean oil (ESO) was converted into its acrylate ester AESO, which can be free-radically copolymerized with reactive diluents like styrene to give thermosetting resins and their foam plastics. Then the bio-foam composites were produced using short sisal fiber as the reinforcement. Effects of fiber loading, length and surface treatment on properties of the foam composites were investigated. It was found that exposure of the fibers to gas cells of the foam reduced the effectiveness of interfacial effect, which is different from conventional bulk composites. As a result, reinforcing ability of sisal fibers became a function of fiber length, loading, etc. Furthermore, the plastic foams based on plant oil resin were proved to be biodegradable in soil burial or in the presence of fungi.
Authors: Wei Zeng, Ming Qiu Zhang, Min Zhi Rong
Abstract: To prepare a novel gas sensor being able to recognize molecules, waterborne poly(β-cyclodextrin-block-polydiethylene glycol hexandioic ester) (i.e., waterborne β-CD-block-PDEA) was synthesized and filled with carbon black (CB). It was found that the composites’ electric resistance remarkably changed when the composites were exposed to the vapors of small size molecule solvents (including dichloromethane, chloroform and tetrahydrofuran, etc.). However, almost no response could be detected in the vapors of large size molecule solvents (like n-pentane, ethylbenzene and hexane). Besides, the responsiveness gradually decreased with increasing molecular size of organic solvents. The results evidenced that the composites have acquired considerable selective sensitivity towards gaseous analytes in terms of their molecular sizes. β-cyclodextrin rather than polydiethylene glycol hexandioic ester played the leading role in this aspect, which was explained from the viewpoint of host-gust chemistry. That is, the response mechanism is mainly based on the molecular discrimination behavior of the host compounds. The small analytes could be entrapped by the β-cyclodextrin cavity due to van der Waals force. On the other hand, solvents’ permittivity also played an important role. The molecules with high permittivity were difficult to enter the hydrophobic cavities. The present study demonstrated the composites could serve as candidates for gas sensors capable of molecule discrimination.
Authors: Ming Qiu Zhang, Min Zhi Rong, Klaus Friedrich
Abstract: To develop wear resistant nanocomposite coating materials, the authors treated nanosilica first by introducing a certain amount of grafting polymers onto the particles in terms of an irradiation technique. Through irradiation grafting, the nanoparticle agglomerates turn into a nano-composite microstructure, which in turn built up a strong interfacial interaction with the surrounding epoxy matrix during the subsequent mixing and consolidation. The experimental results indicated that the addition of the grafted nanosilica into epoxy significantly reduced wear rate and frictional coefficient of the matrix at low filler loading. Compared with the cases of microsized silica and untreated nanosilica, the employment of grafted nanosilica provided the composites with much higher tribological performance enhancement efficiency.
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