Maryline Rochery

Microencapsulation of phosphate: application to flame retarded coated cotton

Polyurethane-phosphates combination is known to form a flame retardant (FR) intumescent system. The intumescent formulation could not be permanent because of the water solubility of the phosphate. This problem could be solved by the technique of microencapsulation. Di-ammonium hydrogen phosphate (DAHP) was microencapsulated with a polyurethane (PU) shell. Polyurethane for textile coating was loaded with neat or microencapsulated DAHP. We studied the thermal degradation behaviour of DAHP microcapsules, PU loaded formulations and cotton coated by these PU formulations. Improvement of the thermal stability for PU textile coating was observed with neat and microencapsulated DAHP. The flame retarding behaviour of these coated cotton fabrics was also valued with the cone calorimeter. This new concept of phosphate encapsulated by PU shell showed a significant FR effect.

Processing and characterization of conductive yarns by coating or bulk treatment for smart textile applications

The use of intelligent materials reacting to external stimuli is rapidly growing in the field of technical textiles. In this paper, the processing of conductive yarns for the development of smart textiles is discussed. Two different methods are exposed: the coating of textile yarns using conductive polymers, and the bulk treatment of spinnable polymers by conductive nanofillers. In the first part of this article, polyaniline (PANI)-coated ultra-high-molecular-weight polyethylene (UHMWPE, Dyneema®) yarns were prepared. Their electrical, morphological and electro-mechanical properties including the temperature influence were investigated. Power handling of PANI-coated conductive yarns as a function of the current was also evaluated. Three different prototypes of conductive multiple yarns have been proposed. In the second part, the use of multi-walled carbon nanotubes as reinforcing conductive nanofiller for spinnable polymers has been studied. The major influence of the homogeneous dispersion of the nanotubes in the host matrix is particularly pointed out, and the electrical behaviour of the nanocomposite yarns has been investigated. Different conductive yarns, developed in our laboratory, are expected to be used as fibrous sensors, connection elements in smart clothing, electro-mechanical or thermal data acquisition devices and conductive fabrics for electromagnetic shielding applications.

Incorporation of poly(dimethylsiloxane) into poly(tetramethylene oxide) based polyurethanes: The effect of synthesis conditions on polymer properties

Two procedures for incorporating low levels of poly(dimethylsiloxane) (PDMS) in polyurethane (PU) have been studied. The bulk synthesis of poly(siloxane-urethane) was performed in two steps: the first involves the formation of a prepolymer between isophorone diisocyanate (IPDI) and poly(tetramethylene oxide) (PTMO). In the second step 1,4-butanediol (BD) was added as the chain extender. A kinetic study followed by infrared spectroscopy showed the higher reactivity of PDMS compared to PTMO. Thus, two procedures for incorporating PDMS are described, depending on whether the poly(dimethylsiloxane) was introduced in the first or in the second step. Films were made from these formulations, and we studied their morphology. The products obtained from each procedure were characterized by size-exclusion chromatography (SEC), differential scanning calorimetry (DSC), dynamic thermomechanical analysis (DMTA) and uniaxial tensile testing, and showed significant differences. These poly(siloxane-urethane) polymers are intended to be used as hydrophobic coated formulations on polyester fabrics in a further study.