Solid surface polymer melts systems

It should be noted that the slip of concern to this paper is that of simple Newtonian liquids against solid surfaces and not the much more widely-accepted slip that can occur when some polymer melt systems are sheared, that is believed to be due to disentanglement of polymer chains attached to the surface from those in the bulk fluid [2],... 

Here, we need to say something about the behaviour of solid surfaces, such as metals, polymers, semiconductors, glasses, ceramics and woods. All these solid substrates have a surface tension like a liquid. Unlike liquids, the intermolecular forces of solids are strong enough (e.g. by lattice forces), to mean that the shape of their surface is not determined by the corresponding surface tension. Above the melting point, provided the solid can melt, such systems have the properties of a typical liquid. So for example, imder the action of the surface tension a curved interface appears. 

The proposed CG models can also be used for the study of systems more complicated than bulk polymer melts. Possible examples are the study of the diffusion of a penetrant in a polymer matrix, or of block copolymers, blends, etc. [121, 122]. In addition, the method can be directly incorporated into multiscale methodologies, which include multiple levels of simulation, and where both atomistic and mesoscopic descriptions are needed at the same time, but in different regions. An example is the study of the long time scale dynamics of polymers near solid attractive surfaces, where an atomistic description is needed very close to the surface but a mesoscopic description can be used for length scales far from the surface. 

Not unexpectedly, Figure 1 shows that the behavior of p near the surface of the filler particles is qualitatively similar to that found for polymer melts near planar solid surfaces [22-24], i.e. it is characterized in all cases by a series of maxima and minima of progressively decreasing intensity with a periodicity approximately 0.8<7. This is true in particular for system Mg,10, in which p reaches its bulk value within approximately 2a from the surface of the particles, as found near planar solid surfaces. The behavior is quite different in the other two cases. In fact, the curve for system Mi6,36 shows a monotonous decrease following the initial series of maxima and minima, and the value of p for r = 20less than unity, while the curve for system Mg,50 shows a complex behavior characterized by the superposition of the series of maxima and minima with periodicity 0.8a with a second series of broad maxima and minima with a periodicity approximately 4complex behavior is observed for the other systems studied, such that intrinsically different p curves are obtained for different systems. In particular, the complexity of the curves is found to increase with increasing size and volume fraction of the filler. 

Introducing fillers in the melt of a binary polymer mixture leads to the following consequences. The main effect is a selective adsorption of one of the components at the interface with the solid. Above the critical point in the phase diagram (for the systems with UCST) polymer melt is a solution of one component into another. The thermodynamic interaction parameter Xab depends on temperature and melt composition. The interaction of each component with the surface is characterized by the thermodynamic parameter of interaction between one of the components and the surface, Xsa or Xsb-In such a system, selective adsorption proceeds, depending on the relation between Xsa tid Xsb- The selectivity of the interaction of the polymer mixture components with the solid plays an important role in the thermodynamic behavior of a filled polymer melt. Let us consider some simple thermodynamic... 

Hot Melt - Hot melt adhesives are based on diermoplastic polymers that are solids at room temperature. Hot melts are appUed at high temperatures, under which they melt and wet the substrate surface. On cooling, the polymer returns to the solid state providing good eohesive strengfli. Two major advantages of the hot melt systems are that they set quickly after being applied (seeonds to minutes) and require no cure and hence have no by-products. 

The affinity of Cgo towards carbon nucleophiles has been used to synthesize polymer-bound Cgo [120] as well as surface-bound Cjq [121]. Polymers involving G q [54, 68, 69] are of considerable interest as (1) the fullerene properties can be combined with those of specific polymers, (2) suitable fullerene polymers should be spin-coatable, solvent-castable or melt-extrudable and (3) fullerene-containing polymers as well as surface-bound Cgo layers are expected to have remarkable electronic, magnetic, mechanical, optical or catalytic properties [54]. Some prototypes of polymers or solids containing the covalently bound Cjq moiety are possible (Figure 3.11) [68,122] fullerene pendant systems la with Cjq on the side chain of a polymer (on-chain type or charm bracelet ) [123] or on the surface of a solid Ib [121], in-chain polymers II with the fullerene as a part of the main chain ( pearl necklace ) [123], dendritic systems III, starburst or cross-link type IV or end-chain type polymers V that are terminated by a fullerene unit For III and IV, one-, two-and three-dimensional variants can be considered. In addition, combinations of all of these types are possible. 

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