Search

In this paper, natural fiber/waterborne polyurethane composites were prepared from the imidazole blocked waterborne polyurethane and eucalyptus fiber mats. The related properties of blocked waterborne polyurethane and natural fiber/polyurethane composites were, respectively, measured by differential scanning calorimetry, dynamic mechanical analysis, dynamic contact angle, water absorption, and scanning electron microscope. The results showed that blocked waterborne polyurethane readily improved storage modulus ( G') and dynamic loss (tanδ) of the composites. The blocked ratio determined the density of the cross-linking structure in natural fiber/polyurethane composite and significantly affected natural fiber/polyurethane composite’s properties. With the increase of the blocked ratio, dynamic mechanical properties showed up a maximum value and the water absorption ratio reached a minimum value. The deblocking reaction of blocked waterborne polyurethane took place between 107.5℃ and 124.5℃. Due to these results, blocked waterborne polyurethane used as a matrix improved the dynamic mechanical properties of natural fiber/polyurethane composite.

This paper describes the preparation of a novel thermosensitive fluorinated surface-active monomer (TFSM) that is based on isophorone diisocyanate(IPDI), dodecafluoroheptanol (FOH), and allyl polyethylene glycol (APEG) with different molecular weights, which is used to prepare thermosensitive fluorinated associating polyacrylamide (TFHPAM) with a functional monomer 2-acrylic amide-2 methyl propyl sulfonic acid (AMPS) through a new micellar system. The thermosensitive self-assembly properties of TFHPAM are studied by viscosimetry, rheology, and dynamic light scattering. The results show that, in room temperature, the self-assembly effects of TFHPAM weakens, and the critical associating concentration (CAC) is increased with the increase in length of polyether side chains in APEG. At the higher temperature, the self-assembly performances of TFHPAM will be enhanced, but CAC is decreased with the increase in length of polyether side chains. Also, the CAC of TFHPAM is decreased along with the increasing temperature. The self-assembly behaviors of TFHPAM via increasing temperature in dilute and semidilute solutions are totally different. At different temperatures, the effects of shear rate on the apparent viscosity of the TFHPAM (via different length of polyether side chains in APEG) solutions are also different. The average apparent aggregate size is increased and the distribution of apparent aggregate size changes from monodispersion to polydispersion, to some extens, with the increase of temperature .