Use of a bis(aminoalkyl)-calix[4]arene derivative as cross-linking agent to enhance functional and mechanical properties of a maleated polypropylene

An isotactic polypropylene grafted by 1 wt% of maleic anhydride (iPP-g-MAH) was chemically modified to provide it with new functional abilities and improved mechanical properties. The specific additive considered in this work is a derivative of bis(aminoalkyl)-calix[4]arene. Not only this molecule serves as a cross-linking agent, but it offers grafting sites for metallic ions that confer electrolytic conductivity to the initially insulating polyolefin. Materials were synthesized by reactive extrusion, and subsequently manufactured as plates by injection molding. The three-dimensional macromolecular architecture was optimized by adjusting the NH₂:MAH molar ratio in a range from 0.5:1 to 1:1. Fourier transform infrared spectroscopy revealed the amine/ anhydride chemical reactions, while gel content measurements were used to determine the degree of cross-linking. The crystalline microstructure of the different materials was characterized by two complementary methods: (a) overall crystallinity by differential scanning calorimetry; (b) lamellar thickness by thermal fractionation using the self-successive auto-nucleation procedure. Only a small decrease of the crystalline lamellae is observed. The mechanical properties were determined by a video-controlled tensile testing method and by Brillouin spectroscopy. A transition from brittle to ductile behavior was observed for increasing cross-links density. Scanning electron microscopy on fracture surfaces showed that ductile fracture was favored by the development of fibrils.     

Enhancement of the Traffic Differentiation Architecture for WBAN Based on IEEE 802.15.4

In the healthcare domain, Wireless Body Area Network has emerged as a vital technology that is capable of providing better methods to diagnose various hazardous diseases. The CANet projet is a project that proposes alternative monitoring solutions. This paper studies the possibility of transmitting different types of information through an IEEE 802.15.4 MAC layer that not supports the transmission of heterogeneous information. We have proposed an extension to the MAC layer which makes possible the transmission of various information types. This solution designed by “diffrentiation layer” uses a purge function to ensure the use of CAP and CFP by the same node in the same superframe and allows the differentiation between several information. Our results show that our solution is reliable under worst-case.