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Polyaniline/1-tetradecanol composites

Form-stable PCMS and electrical conductive materials

Journal of Thermal Analysis and Calorimetry
Authors: J. Zeng, J. Zhang, Y. Liu, Z. Cao, Z. Zhang, F. Xu, and L. Sun

Abstract  

Polyaniline (PANI)/1-tetradecanol (TD) composite materials, a kind of novel composite that can conduct electricity and store thermal energy at the same time, thus possess the ability to endure certain heat shock, were prepared for the first time. FTIR and XRD results showed that there were some interactions existed between PANI and TD. The thermal stability of the composites exhibited both the characteristics of PANI and TD. The DSC experiments showed that the highest phase change enthalpy of the composites could be as 73% as that of TD, indicating it was a good form-stable phase change material. The thermal conductivity of the composites was also improved. The AC (Alternating Current) conductivity of the composites was enhanced to close to that of PANI when the mass fraction of PANI in the composite was increased to 46%. Heat shock experiments showed that the heat shock resistibility of the composite was greatly improved comparing to that of pure PANI.

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Abstract  

By dissolution of PVC and polyaniline in dimethylformamide, a series of blends PVC-polyaniline were produced which were studied by scanning electron microscopy and thermogravimetry. Special attention is focused on the kinetic study of the thermal degradation steps by using non-isothermal thermogravimetric data. The results show that the thermal stability of the synthesized blend is decreased as the total amount of polyaniline is enhanced. Furthermore, the Brřnsted acid doped blend is more stable than the corresponding undoped one. PVC and the PVC-polyaniline blends exhibit two mass loss steps which activation energy values are in the range from 176 to 283 kJ mol-1 and 306 to 322 kJ mol-1, respectively.

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Abstract  

A series of blends of poly(vinyl chloride) (PVC) and polyaniline (PANI) was prepared by solution casting and investigated by methods of thermal analysis, namely thermogravimetric analysis (TG), coupled with Fourier transform infrared spectroscopy (TG-FT/IR) and differential scanning calorimetry (DSC). It was found that the thermal stability of this polymer system depends on the composition of blend; the main product of prevailing PVC decomposition process — hydrogen chloride — seems to play specific role during degradation since it can react with PANI structures, characterized by different protonation degree.

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Abstract  

The thermal behaviour of polyaniline-‘emeraldine base’ (PANI-EB) was studied using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). We assume that during heating over 150C three exothermal processes proceed - reorganization and crosslinking between PANI-EB chains followed by post-polymerization. The low temperature relaxation transition for PANI-EB was registered for the first time by DSC. We suppose that it might be due to the motion of polymer chains non-crosslinked during the first heating, chain fragments resulting from high-temperature decomposition over 300C and chain ends of the already crosslinked polymer.

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Abstract  

The thermal behaviour of polyaniline plasticized by an oligoester of phosphoric acid was investigated by means of thermogravimetry, either alone or coupled with Fourier transform infrared spectroscopy, and differential scanning calorimetry. It was found that additional thermal transitions, resulting from the dopant, occur in the temperature range 200-250C. The emission of volatile products, as evidenced by the Gram-Schmidt chromatograms, was suppressed by the plasticizer used. This stabilization was probably due to a decreased possibility of diffusion in the three-dimensional honeycomb polymer-plasticizer structure.

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Abstract  

Conducting polyaniline/Cobaltosic oxide (PANI/Co3O4) composites were synthesized for the first time, by in situ deposition technique in the presence of hydrochloric acid (HCl) as a dopant by adding the fine grade powder (an average particle size of approximately 80 nm) of Co3O4 into the polymerization reaction mixture of aniline. The composites obtained were characterized by infrared spectra (IR) and X-ray diffraction (XRD). The composition and the thermal stability of the composites were investigated by TG-DTG. The results suggest that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the thermal stability for the composites is attributed to the interaction between PANI and nano-Co3O4.

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Abstract  

A structural study of conductive composite films consisting of ethylene-co-vinylacetate (EVA) copolymer, polyaniline (PANI) and dodecylbenzenesulfonic acid (DBSA), a part of which being complexed with PANI, was performed by using differential scanning calorimetry (DSC) and presented for the first time. An additional crystalline phase is formed during the film formation by thickening EVA chain-folded lamellae with participation of‘free’ DBSA molecules at lower net PANI content (up to 5 mass%) and of both ‘free’ and complexed DBSA molecules (up to 7.5 mass%). At higher PANI content PANI-DBSA complex starts to form its own crystals and at 17.5 mass% of PANI mixed crystals of EVA with ‘free’ DBSA alkyl chains are preferably formed. It is also found that the Fox' equation correlating the glass transition temperature of a miscible blend system with its composition can be actually used in estimating the miscibility of EVA/PANI blends no matter the presence of DBSA.

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Abstract  

Thermal transporting properties of electrically conductive polyaniline films were first investigated in wide range of temperatures above room temperature as organic thermoelectric materials. Thermal conductivities of various protonic acid-doped polyaniline films were measured by combination of a laser flash method and a differential scanning calorimeter in relation with electrical conductivity and a kind of dopant. The thermal conductivities thus measured are in the range of conventional organic polymers, indicating that the doped polyaniline films have extremely low thermal conductivities among electrically conductive materials, and have correlation with neither electrical conductivity, nor a kind of dopant. Consequently the polyaniline film, which shows very high electrical conductivity, has comparable thermoelectric figure-of-merit (ZT) with feasible inorganic thermoelectric materials such as iron silicide.

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Abstract  

Structural studies of powdered polyaniline (PANI) prepared in aqueous medium by the oxidative polymerization of aniline in the presence of dodecylbenzenesulfonic acid(DBSA) were performed by means of DSC and WAXS. The influence of the alkyl side-chains on the structure and crystallinity of the as-synthesized PANI—DBSA and on the structural transitions taking place in PANI upon washing and heating were investigated. It was found that DBSA induces crystallinity in the rigid matrix of PANI, and residual crystalline phases were also observed after the deprotonation of PANI—DBSA. For the first time, a melting peak and a relaxation transition of non-cross-linked PANI were registered.

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Abstract  

The long-term environmental ageing of conductive composite films containing ethylene-co-vinyl-acetate (EVA) copolymer and a complex of polyaniline (PANI) and dodecylbenzenesulfonic acid (DBSA) was studied by using differential scanning calorimetry (DSC). We assume that both phase separation and crosslinking of PANI main chains occur in the systems. On the other hand, the competition between PANI–DBSA complex self-organization and crystallization of EVA matrix result in structural changes and formation of continuous conductive network, responsible for significantly increased (ca five orders of magnitude) electrical conductivity of the aged films.

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