Casting and Evaporating

Another way to reduce the mobility is by forming two-dimensional monolayers under ambient conditions. Adsorbate-substrate and adsorbate-adsorbate interactions lower the molecular mobility and are responsible for the two-dimensional ordering, Dry monolayers can be formed by drop casting and evaporation or by the horizontal lifting technique.It is also possible to measure... 

Fig. 3.27 Scanning electron micrographs of the cryo-fractured surfaces of unvulcanized natural rubber/CW obtained by casting and evaporating (a) and freeze-drying and hot-pressing (b) [39]...

Other nano-fillers have also investigated. Cao et al. [253] reported the utilization of multiwalled carbon nanotubes (MWCNTs) as filler-reinforcement to improve the performance of plasticized starch (PS). The PS/MWCNTs nanocomposites were prepared by a simple method of solution casting and evaporation. The results indicated that the MWCNTs dispersed homogeneously in the PS matrix and formed strong hydrogen bonding with PS molecules. Besides the improvement of mechanical properties, the incorporation of MWCNTs into the PS matrix also led to a decrease in the water sensitivity of the PS-based materials. 

The development of foams for medical purposes was described by Radusch [193], To eliminate thermal degradation, as well as to avoid the problems associated with the low melt viscosity, a process was developed based on solvent casting and subsequent particle leaching. Well-defined porous structures can be formed in such a way [197-200], for example, PHB was dissolved in chloroform, the ensuing solution was mixed with water-soluble particles like NaCl, films were then prepared by solvent casting and evaporation and, subsequently, the salt particles were washed out with water. Various foamed structures were thus prepared, depending on the particle size and amount, as well as other parameters, such as the PHB type and its concentration in the chloroform solution. 

An instrumental characterization of nano-hydroxyapatite was provided by Chen et al. (2002) the size of their particles was ca. 20-30 nm in width and 50-60 nm in length, with a specific surface area of 73 m /g aggregation was avoided with the use of n-butanol. The uniform dispersion of these particles in chitosan solutions was recognized as an important motif for the innovative preparation of chitosan composites in fact, nano-hydroxyapatite + chitosan composite membranes prepared by solvent casting and evaporation were found suitable for guided bone regeneration. 

Abraham et al. reported that films of pre-vulcanized NR nanocomposite were fabricated by casting and evaporating a mixture of NR latex and aqueous suspension of cellulose nanofibrils (CNF). By this method, the CNF were evenly distributed in the NR composites. The increase of CNF content in the NR matrix caused the increasing the Young s modulus and tensile strength of materials, but the decreasing characteristic rubber elongation. The enhancements in mechanical and dynamic mechanical properties were attributed to the formation of a Zn ellulose complex and the three dimensional network of the CNF in the NR matrix as a result of the deprotonation of the cellulose. 

This technique is also a kind of casting and evaporating technique which is used for polysaccharides modified by various surface chemical reactions. With improved hydrophobicity, these nanocrystals can disperse in non-aqueous solvents and be more compatible with hydrophobic polymers. Therefore, non-aqueous solution mixing techniques are possible for preparing well-dispersed polymer/polysaccharide nanocrystals nanocomposites. 

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