Polymer interfacial

Van Duin, M. and Borggreve, R., Blends of polyamides and maleic anhydride containing polymers Interfacial chemistry and properties, in Reactive Modifiers for Polymers, Al-Malaika, S. (Ed.), Blackie Academic Professional, London, 1997. 

CNT can markedly reinforce polystyrene rod and epoxy thin film by forming CNT/polystyrene (PS) and CNT/epoxy composites (Wong et al., 2003). Molecular mechanics simulations and elasticity calculations clearly showed that, in the absence of chemical bonding between CNT and the matrix, the non-covalent bond interactions including electrostatic and van der Waals forces result in CNT-polymer interfacial shear stress (at OK) of about 138 and 186MPa, respectively, for CNT/ epoxy and CNT/PS, which are about an order of magnitude higher than microfiber-reinforced composites, the reason should attribute to intimate contact between the two solid phases at the molecular scale. Local non-uniformity of CNTs and mismatch of the coefficients of thermal expansions between CNT and polymer matrix may also promote the stress transfer between CNTs and polymer matrix. 

The interaction of two substrates, the bond strength of adhesives are frequently measured by the peel test [76]. The results can often be related to the reversible work of adhesion. Due to its physical nature such a measurement is impossible to carry out for particulate filled polymers. Even interfacial shear strength widely applied for the characterization of matrix/fiber adhesion cannot be used in particulate filled polymers. Interfacial adhesion of the components is usually deduced indirectly from the mechanical properties of composites with the help of models describing composition dependence. Such models must also take into account interfacial interactions. 

Gersappe [250] used an MD simulation to probe the molecular mechanisms by which nanofillers reinforce the polymer matrix. Liao and Li [251] used Molecular Modeling to quantify CNT-polymer interfacial shear stress and found it to be about one order of magnitude higher than that of microfiber-reinforced composites. 

Over the past fifteen years a number of different approaches have been taken in an attempt to increase the durability of the metal/polymer interfacial region in the presence of water. These attempts have met with varied degrees of success. However, to date adhesion scientists are still searching for a means of achieving sufficient wet environment durability, so that the enormous potential of metal/polymer adhesion systems can soon be utilized effectively. The authors have selected to discuss a few of the more promising durability-enhancing methods. 

Thus, it was shown that many building blocks of natural and synthetic polymers are amphiphilic and interfacially active. For the monomers of several important water-soluble polymers, interfacial activity prevails over affinity to either bulk phase. Accordingly, it appears relevant to try to predict... 

The use of surfactants and the chemical functionalization of CNT surfaces have also been investigated in efforts to improve CNT dispersion as well as enhance the CNT-polymer interfacial bond (10,27-29). However, although chemical functionalization can lead... 

Once a micelle is stung, polymerization proceeds very rapidly. The particle can accommodate more monomer as its polymer content increases and the water-polymer interfacial surface increases concuirently. Tlie new surface adsorbs emulsifier molecules from the aqueous phase. This disturbs the equilibrium between micellar and dissolved soap, and micelles will begin to disintegrate as the concentration of molecularly dissolved emulsifier is restored to its equilibrium value. Thus the formation of one polymer particle leads to the disappearance of many micelles. The initial latex will usually contain about 10 micelles per milliliter water, but there will be only about 10 particles of polymer in the same volume of the final emulsion. When all the micelles have disappeared, the surface tension of the system increases because there is little surfactant left in solution. Any tendency for the mixture to foam while it is being stirred decreases at this time. 

Table IV lists the best performance data obtained for piperazine oligomer membranes interfacially reacted with isophthaloyl chloride. The objective of these tests was to achieve single-pass seawater desalination membranes. As such, the presence of free carboxylate groups was avoided use was made of the trimesoyl chloride or alternate triacyl halides in the oligomer formation step, and diacyl chlorides in the interfacial reaction step. A few samples of seawater desalination membranes were obtained. Best results were seen for piperazine-cyanurate pre-polymers interfacially cross-linked by isophthaloyl chloride, but fluxes were low in view of the operating test pressure of 1500 psi (10 342 kPascal). Also, individual membrane results with piperazine oligomers were equally as erratic as those experienced for piperazine directly. The only notable advantage of the piperazine oligomer approach was the ability to incorporate...

Pasche, S. et al., Poly(L-lysine)-graft-poly(ethylene glycol) assembled monolayers on niobium oxide surfaces A quantitative study of the influence of polymer interfacial architecture on resistance to protein adsorption by ToF-SlMS and in situ OWLS, Langmuir, 19, 9216, 2003. 

The second section. Perspective Macro- and Microinteractions of Water and Polymers, consists of three chapters. It covers a brief historical introduction leading to an insight into selected aspects of current thought on interactions of water with model solutes and proteins [4], consideration of water-polymer and ice-polymer interfacial regions [5], and examination of stages in the process of protein hydration assessed by a variety of types of measurements [6]. 

Helfand E, Bhattaoharjee S M and Fredrickson G H 1989 Molecular weight dependence of the polymer interfacial tension and oonoentration profile J. Chem. Phys. 91 7200... 

Orientation at the interface between polymers and metals where the polymer transfer to the metal can be determined with quantitative absorption-reflection thickness infrared spectroscopy. With an understanding of polymer interfacial orientation, bonding mechanisms can be identified and accordingly adhesion of polymers to metals better understood. 

Y j, = cell-liquid interfacial free energy = cell-polymer interfacial free energy... 

Chemical functionalization of CNT surfaces could improve their dispersion in the polymer matrix and enhance the nanotube-polymer interfacial interaction and the mechanical load transfer. The effects of nanotube functionalization on the properties of CNT-TPU composites have been investigated in details. Xia and Song have synthesized polycaprolactone polyurethane (PU)-grafted SWNTs (PU-g-SWNTs) and corresponding PU-g-SWNT-PU composites by in-situ polymerization. The results show that PU-g-SWNTs improve the dispersion of SWNTs in the PU matrix and strengthen the interfacial interaction between the PU and SWNTs. Compared with neat PU and pristine SWNT PU composites, PU-g-SWNT-PU composites demonstrate remarkable enhancement on Young s modulus. The Young s modulus of a 0.7 wt /o PU-g-SWNT-PU composite increases by 178% over the blank PU and 88% over the 0.7 wt% pristine SWNT-PU composite, respectively. 

The Influence of Polymer Surface Functional Groups in Metal/Polymer Interfacial Chemistry... 

In some cases extensive chcmisiiy may occur and it may not be appamn in the polymer or metal cote levels. Based on the abovc-meniioned eflccts, any photocmitsioa investigaiioii into metal/polymer interfacial chemisuy should include analysis of not only the polymer and metal com levels, but also the valence band regions. The use of molecular orbital calculations to model specific metal/polymer interactions can also be very useful in imeiiuciiBg the photoemission spectra. 

Metal/Polymer Interfacial Interactions Chromium-FIuorinated Polylary ether)... 

Metal/Polymer Adhesion Effect of Ion Bombardment on Polymer Interfacial Reactivity... 

In polymer blends, these phenomena are complicated by the possible interactions between both polymers. Interfacial cross-linking could take place... 

The new features of the current work relate to the approach adopted in the modeling of the polymer matrix and the investigation of the CNT polymer interfacial properties as appose to the effective mechanical properties of the RVE. The idea behind the ABC technique is to incorporate atomistic interatomic potentials into a continuum framework. In this way, the interatomic potentials introduced in the model capture the underlying atomistic behavior of the different phases considered. Thus, the influence of the nanophase is taken into account via appropriate atomistic constitutive formulations. Consequently, these measures are fundamentally different from those in the classical continuum theory. For the sake of completeness, Wemik and Meguid provided a brief outline of the method detailed in their earlier work [133-134]. 

For polymers interfacial and surface tensions are more practically obtainable from analysing the shapes of pendant or sessile drops or bubbles, all of which are examples of axisymmetrical drops. Bubbles may be used to obtain surface tensions at liquid/vapour interfaces over a range of temperatures and for vapours other than air. Drops can also be used to obtain vapour/liquid surface tensions but they are particularly suited to determination of liquid/liquid interfacial tensions, for example for polymer/polymer interfaces. All the methods are based on the application of equation (2.2.1). The principles are illustrated in figure 2.4, in which a sessile drop is used as the specific example. Just like for the capillary meniscus, the drop has two principal radii of curvature, R in the plane of the axis of symmetry and / 2 normal to the plane of the paper. At the apex, O, the drop is spherically symmetrical and R = Rz = b and equation (2.2.12) becomes... 

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