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981.
982.
983.
Surface‐pegylated chitin whiskers as an effective additive to enhance the mechanical properties of recycled ABS 下载免费PDF全文
The recyclability of materials is a key issue related to the use of polymers in the automotive and electronic industries, among others. The multiple thermal and mechanical operations used in recycling can cause severe damage to the molecular architecture and microstructure of polymers that frequently leads to a reduction in their mechanical properties, which restricts their recyclability. In this work, nanocomponents (whiskers) derived from chitin were surface‐modified by grafting different molar masses of methoxylated poly(ethylene glycol) (mPEG). The modified chitin whiskers were then incorporated into reprocessed ABS (acrylonitrile–butadiene–styrene) to yield nanocomposites with 0.5% (mass/mass) whiskers. The obtained whiskers and nanocomposites were investigated using techniques such as transmission electron microscopy, atomic force microscopy, scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis. The properties of the nanocomposites were also investigated using tensile tests and dynamic mechanical tests. The results show that the surface‐modified chitin whiskers with high molar mass mPEG grafts increased the strength, elongation at break, and stiffness of the reprocessed ABS over virgin and reprocessed ABS and reprocessed ABS nanocomposites with unmodified whiskers. This indicates that the use of surface‐modified chitin whiskers can be valuable in improving the mechanical properties of recycled polymers and, consequently, enhancing their recyclability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42463. 相似文献
984.
We investigate the mechanical properties of inclined frictional granular layers prepared with different protocols by means of DEM numerical simulations. We perform an orthotropic elastic analysis of the stress response to a localized overload at the layer surface for several substrate tilt angles. The distance to the unjamming transition is controlled by the tilt angle $\alpha $ with respect to the critical angle $\alpha _c$ . We find that the shear modulus of the system decreases with $\alpha $ , but tends to a finite value as $\alpha \rightarrow \alpha _c$ . We also study the behaviour of various microscopic quantities with $\alpha $ , and show in particular the evolution of the contact orientation with respect to the orthotropic axes and that of the distribution of the friction mobilisation at contact. 相似文献
985.
986.
Automated system to acquire fluorescence, polarization and anisotropy maps within liquid flows 总被引:1,自引:0,他引:1
Cristina M. Quintella Cristiane C. Gon?alves Iuri Pepe Angelo M. V. Lima Ana Paula S. Musse 《Journal of Automated Methods and Management in Chemistry》2002,24(2):31-39
Maps of polarization and anisotropy can be helpful for flow analysis systems (FIA, CFA, etc.) with reactions dependent on the intermolecular alignment as well as for dispersion control. Maps can be acquired manually, but when a scan over a sample area is required, the acquisition becomes tiresome and has low precision. The paper describes an automatic flexible system for high-precision sample positioning with closed loop self control, remote data acquisition and storage controlled by a BASIC program. The system was developed to acquire maps up to 850 mm(2) of the sample (liquid flows, solids, interfaces, etc.), with up to 100 mum(2) precision. To evaluate the equipment, performance is presented as the scan of a thin liquid film of monoethylene glycol (MEG) flowing on borosilicate. Tests were performed with and without surfactantes at submicellar concentrations: two concentrations of sodium dodecyl sulphate (SDS) and one of polyethylene oxide (PEO). For pure MEG, the intermolecular alignment initially increased, then decreased. When SDS was added, both polarization and anisotropy only increased progressively with the flow. This might be explained by the surfactant decrease of interfacial interaction. When PEO was added, both polarization and anisotropy decreased pronouncedly over the entire map, which might be due to macromolecular aggregates within the bulk generating misaligned molecular domains. The system presented as sample positioning repeatability of 0.1% and a high polarization reproducibility (error margin < 6 in 1000). 相似文献
987.
Insightful knowledge on quantum nanostructured materials is paramount to engineer and exploit their vast gamut of applications. Here, a formalism based on the s... 相似文献
988.
989.
Rosmary N. Brandalise Mara Zeni Johnny D. N. Martins Maria M.C. Forte 《Polymer Bulletin》2009,62(1):33-43
Summary Blends of post-consumer high density polyethylene (HDPEr) and poly(vinyl alcohol) (PVA) were prepared with maleic anhydride-grafted
HDPEr (HDPEr-AM), as the compatibilizer, to evaluate the effectiveness of the PVA as a modifier for polyethylene and influence
of PVA concentration on the blend properties. Films of polyethylene having biodegradable polymers could be a good solution
for agricultural purpose since they can degrade more easily. The blends HDPEr/HDPEr-AM/PVA were investigated by physical tests,
dynamic-mechanical analysis (DMA) and scanning electron microscopy (SEM). Thermal properties were measured by means of differential
scanning calorimetry (DSC). The blend HDPEr/HDPEr-AM/PVA (50/10/40) with 10wt% of compatibilizer showed the highest tensile
strength (28 MPa) compared to the blends (60/40) without compatibilizer (11 MPa). On the other hand, morphologic analysis
showed synergism of the polymers in the blend HDPEr/HDPEr-AM/PVA (30/10/60), with 10wt% of compatibilizer. Overall, it was
observed that the blend HDPEr/HDPEr-AM/PVA with composition of (70/10/20) showed the best properties for agricultural films
processing application. 相似文献
990.
The present work focus the study of cortical bone samples of different origins (human and animal) subjected to different calcination temperatures (600, 900 and 1200 °C) with regard to their chemical and structural properties. For that, not only standard techniques such as thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy were used but also mercury intrusion porosimetry. The latter technique was applied to evaluate the effects of the temperature on the microstructure of the calcined samples regarding porosity and pore size distribution. 相似文献