Poly , bonding composites

Supramolecular interactions were also utilized in synthesis of carbon nanotube/poly-propylene composites (see chapter Applications of Ball Milling in Nanocarbon Material Synthesis). Solid-state grafting of maleated polypropylene on the surface of multiwalled carbon nanotubes (MWCNTs) employs interactions of carbonyl and carboxyl groups with maleic anhydride groups via hydrogen bonds or other dipole-dipole interactions [8]. 

Spun-bonded composites, on the other hand, are mainly produced from poly(ethylene), poly(propylene), and aromatic polyesters. Area-bound products behave more like paper, but point-bound products are more like fleeces (Table 38-6). In these cases, composites from poly(ethylcne) and poly-(propylenc) arc purely thermally welded without the use of adhesives the resulting products span the whole of the area of application between heavy packing papers to fine writing papers. The poly(ethylene) papers can be... 

In situ oxidative polymerization has also been used to prepare/PE/poly-aniline composites. In one approach, microporous PE films were immersed in a solution of aniline hydrochloride and polymerization was started by the introduction of ammonium peroxydisulfate [23]. Similarly, Wan and Yang (1993) obtained PE/polyaniline composites using iron (III) chloride as the oxidant [24]. Solution blending is largely utilized to prepare blends and composites where one or more of the components do not melt easily or are heat susceptible. ICPs Hke polyanifine are difficult to process due to their aromatic structure, interchain hydrogen bonds and effective charge delocahzation in their structures. 

Poly(vinyl acetate). The dielectric and mechanical spectra of hybrids produced by mixing a poly(vinyl acetate)—THE solution with TEOS, followed by the addition of HCl have been investigated (45). Mixtures were made which were beheved to be 0, 5, 10, 15, and 20 wt % Si02, respectively. These composites were transparent and Eourier transform infrared spectroscopy (ftir) revealed hydrogen bonding between the siUcate network and carbonyl units of the poly(vinyl acetate) (PVAc). No shift in the T of the composites from that of the pure PVAc was observed. Similarly, the activation... 

Thermoplastic elastomers are often multiphase compositions in which the phases are intimately dispersed. In many cases, the phases are chemically bonded by block or graft copolymerization. In others, a fine dispersion is apparentiy sufficient. In these multiphase systems, at least one phase consists of a material that is hard at room temperature but becomes fluid upon heating. Another phase consists of a softer material that is mbberlike at RT. A simple stmcture is an A—B—A block copolymer, where A is a hard phase and B an elastomer, eg, poly(styrene- -elastomer- -styrene). 

Good bonding was obtained to several substrates under aqueous conditions. Values obtained were 41 to 10-3 MPa to composite resins, and 9-8 to 15-6 MPa to stainless steel (Table 9.6). They were also reported as adhering to porcelain. No adhesion was obtained to untreated dentine or enamel. The cements could be bonded to enamel etched with add (3-5 MPa) and to dentine conditioned with poly(acrylic acid) (10 MPa). 

An example of the large variety of monomer structures present in poly(HAMCL) is given in Fig. 2. Also different degrees of unsaturation in poly(HAMCL) can be established relatively easily [3-5,34-39]. For example, the compositional data in Table 1 for the repeat units show that about 16% of the mono-unsaturated double bonds are incorporated when oleic acid is used as feedstock. When tall oil fatty acids are used, over 40 % of the subunits of the resulting poly(HAMCL) are mono- or di-unsaturated, while the total degree of unsaturation of the alkyl side chains of linseed oil-based PHA is even higher (>65%). Moreover, a substantial part (about 30%) of these unsaturated linseed oil-based poly(HAMCL) subunits have up to three double bonds present. 

Philippova and Starodubtzev have also extensively studied the complex-ation behavior of polyacids and PEG, especially, the system of crosslinked of poly(methacrylic acid) and linear poly(ethylene glycol) (Philippova and Starodubtzev, 1995 Philippova et al., 1994). They observed that decreasing the molecular weight of PEG from 6000 to 1500 resulted in its slower diffusion into the swollen network of PMAA, and a drastic decrease in both the stability and equilibrium composition of the intermacromolecular complex. Analysis of dried polymer networks of PMAA with absorbed PEG chains by FT-IR spectroscopy revealed the presence of two types of hydrogen bonded structures (1) dimers of methacrylic acid at absorption frequency of 1700 cm-1 and (2) interpolymer complexes of PMAA and PEG at 1733 cm-1. In addition, they also suggested as a result of their studies, that the hydrogen bonded dimer of PMAA forms preferentially to the intermacromolecular complex between the PMAA network and PEG chains. 

Based on the solution property of poly (DMAEMA-co-AAm) in response to temperature, the temperature dependence of equilibrium swelling of poly (DMAEMA-c6>-AAm) gel as a function of chemical composition was observed as shown in Figure 6. The transition temperature of copolymer gel between the shrunken and swollen state was shifted to the lower temperature with increases in AAm content in the gel network. This is attributed to the hydrogen bond in the copolymer gel network and its hydrophobic contribution to the LCST Copolymer II gel was selected as a model polymer network for permeation study because it showed the sharp swelling transition around 34°C. 

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