The composite of linear low density polyethylene (LLDPE) with carbon black (CB) and inorganic flame retardant (aluminum hydroxide, Al(OH)3) was prepared by melt-blending method. The effect of cross-linking on the stability of positive temperature coefficient (PTC) of composite and the elimination of negative temperature coefficient (NTC) of composite were investigated. LLDPE was chemically cross-linking with different contents of initiator (dicumyl peroxide, DCP). The cross-linking effects of composite were analyzed by gel content analysis, differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). By the effect of DCP, not only the composite appeared a high PTC intensity, but also the NTC effect of composite was eliminated. In this investigation, the optimum PTC intensity of composite reached 5.87 orders of magnitude for the composition of LLD0.l0C33.7A28, and the PTC transitional temperature of composite decreased with increasing of DCP content. In addition, the good reproducibility of composites was proved by thermal cycling, and successfully passed the test of over-voltage resistance. 相似文献
Argon plasma-pretreated high-density polyethylene (PHDPE) was blended with the conductive nano carbon black (CB) and inorganic flame retardant (magnesium hydroxide, Mg(OH)2) was added. Influences of the CB content, plasma treatment time, plasma treatment power, and dosage of 60Co γ-ray radiation on positive temperature coefficient (PTC) behaviors of composite were studied. In addition, the over-voltage resistance behavior of the composites was also investigated. The free radical of PHDPE was measured by 1,1-diphenyl-2-picryhydrazyl (DPPH) method. The gel contents of composite were measured by solvent extraction method. The results showed that the room-temperature volume resistivity and PTC effect of composite were improved significantly with plasma treatment. The PHDPE composite with 60Co γ-ray radiation eliminated the negative temperature coefficient (NTC) effect in the composites effectively, and the PTC intensity of composite was increased. With increasing of radiation dosage from 20 Mrads to 80 Mrads, the gel content of composites increased up to 83.84% and the response temperature of composites shifted to low temperature (127.5 °C to 114.8 °C). In this work, the composites also successfully passed the over-voltage resistance test, and possessed good reproducibility. 相似文献
A simple and fast way to measure proton self‐diffusion coefficients of small penetrant molecules in semicrystalline polymers is introduced. The approach takes advantage of the strong static gradient of a mobile single‐sided NMR sensor and it is demonstrated on PE samples with varying degrees of crystallinity fully saturated in either toluene or n‐hexane. The self‐diffusion coefficients were measured using the gradient stimulated echo sequence appended with a CPMG. It is also shown for the first time, with demonstration on PE plates several millimeter thick with different aging histories, that one‐dimensional profiles of self‐diffusion coefficients as a function of depth can be easily obtained. 相似文献
Get a whiff of this : Human olfactory receptor (hOR)‐conjugated polypyrrole (PPy) nanotubes were integrated into the field‐effect transistor (FET) sensor platform for the fabrication of high‐performance bioelectronic noses (see picture, S=source, D=drain). The device can translate and amplify hOR–odorant interaction into a detectable signal, and it showed highly sensitive and specific responses toward a target odorant.
Summary: An all‐polymer field‐effect transistor (FET) fabricated using an inkjet printing technique is presented in this paper. Poly(3,4‐ethylenedioxythiophene) works as the source/drain/gate electrode material because of its good conductivity. Polypyrrole acts as the semiconducting layer. Poly(vinyl pyrrolidone) K60, an insulating polymer with a dielectric constant of 60, operates as the dielectric layer. All the polymers are diluted with deionized water, and can be printed with a piezoelectric inkjet printing system. The device functions at a depletion mode with low operation voltage. It has a field‐effect mobility of 0.1 cm2 · V−1 · s−1, an on/off ratio of 2.9 × 103, and a subthreshold slope of 2.81 V · decade−1.
Schematic of the all‐polymer FET synthesized here. 相似文献
We report the synthesis and characterization of a polysaccharide crosslinker of tetraaniline grafting oxidized sodium alginate with large aldehyde and carboxylic groups. We demonstrate that this copolymer has the following properties: it is water soluble under any pH, biodegradable, electroactive, and noncytotoxic; it can self-assemble into nanoparticles with large active functional groups on the outer surface; it can crosslink materials with amino and aminoderivative groups like gelatin to form hydrogels, and thus the electroactivity is readily introduced to the materials. This copolymer has potential applications in biomedical fields such as tissue engineering, drug delivery, and nerve probes where electroactivity is required. 相似文献
To establish the correlation between the thermoelectric properties of conducting polymers and their doping levels, we have utilized the potential-step chronocoulometry for the quantitative estimation of the doping levels. In this paper, three types of poly(3-hexylthiophene)s synthesized by different polymerization methods were investigated. The electrical conductivities and the Seebeck coefficients of poly(3-hexylthiophene)s with various doping levels were measured and plotted against the doping level. It was found that the electrical conductivity linearly increased with increasing the doping level in the range of 1–10%, and then saturated. On the other hand, the relationship between the Seebeck coefficient and the doping level showed a good linearity in all the polymers. 相似文献
The time dependence of dc conductivity of conducting polyaniline films was measured in relation to temperature and relative humidity of the environment. Optical and structural properties of the samples were checked using Fourier transform infrared (FTIR) spectroscopy. 相似文献