Resins hybrid

In more complex forms of this resin hybrid, other dimethacrylates may be present, such as the ethylene glycol dimethacrylates, and bis-GMA, when HEMA acts as a co-solvent for water and bis-GMA (Antonucd, McKinney Stansbury, 1988). The general composition of these materials, which we term class I hybrids, is summarized below ... 

Figure 35. Mechanical properties of carbon/carbon epoxy-resin hybrid composites, compared with the properties of the composite skeletons before resin impregnation (61,62). The composite skeletons were prepared from Sigrafil HM 3 PAN-based fiber, rigidized with a phenolic resin, and densified by four cycles with coal-tar pitch plus sulfur the carbonization temperature was 1000°C. (a) Young s modulus.

Figure 9.34 The composites frequency dependence of reflection coefficient at different filler s amount PANI-PTSA/epoxy resin composites (a), PANI-PTSA/FCjOyepoxy resin hybrid composites (b), PANI-PTSA (15%)/Fe30 (10%)/epoxy resin hybrid composites at different thickness (c), and the comparison of measured and calctdated reflection coefficient for PANI-PTSA (15%)/Fe30 (10%)/epoxy resin hybrid composite (d). Reprinted from Ref. [61] with permission from Elsevier.

Property Unsaturated polyester resin Hybrid polymer network (HPN) HPN with chain extender Polyester- polyurethane network... 

The sol-gel process has been examined as a cost-effective alternate for expensive and somewhat complicated polycarbosilane route, and to reduce the carbothermal reaction temperature. Tanaka and Karachi used the silica-organic resin hybrid, which was made by the toluenesulfonic acid-catalyzed hydrolysis ofTEOS in the presence of proper amount of phenolic resin, as the precursor for SiC powders (Tanaka, 1988). They obtained finely divided and highly sinterable /S-SiC powders almost free from Si02 and excess carbon. The two-step hydrolysis of TEOS/novolac resin mixture (catalyzed by oxalic acid in the first step and hexamethyltetramine in the second step) provided gels, which also transformed to nearly pure greenish 6-SiC powders (O 0.5 wt%, N 0.4 wt%) (Li, 2000). 

Such Si02-phenolic resin hybrids have been found to be easily formed to fibers if the hydrolysis condihons (the amount of water and/or catalyst) were properly adjusted (Hasegawa, 1995), and spun fibers with C/Si ratios of 2.6-4.3 were converted to SiC fibers containing excess free carbon only by 2 wt% and no silica at 1500°C in the inert... 

TEOS-phenolic resin hybrid Hasegawo, 1997a... 

Zr(0 C4H9)4-phenollc resin hybrid Hasegawa, 1999o... 

MMA-nBA-AA Alkyd resin Acrylate/alkyd resin hybrids prepared by miniemulsion polymerization potential coating applications 820... 

Wang, Y., Spencer, P., Yao, X., Brenda, B. Effect of solvent content on resin hybridization in wet dentin bonding. J. Biomed. Mater. Res. Part A 82,975-983 (2007)... 

Thermosetting-encapsulation compounds, based on epoxy resins (qv) or, in some niche appHcations, organosiHcon polymers, are widely used to encase electronic devices. Polyurethanes, polyimides, and polyesters are used to encase modules and hybrids intended for use under low temperature, low humidity conditions. Modified polyimides have the advantages of thermal and moisture stabiHty, low coefficients of thermal expansion, and high material purity. Thermoplastics are rarely used for PEMs, because they are low in purity, requHe unacceptably high temperature and pressure processing conditions. 

Acryflc coating powders have achieved some success in Japan utilizing resins having gflcydyl methylacrylate functionality cured with C q—0 2 dicarboxyflc acids (49). Hybrid polyester—acryflc coating powders have also been reported in which an acid functional polyester resin coreacts with a glycidyl-containing acryflc polymer (50). Hydroxyl functional acryflc resins cured with blocked isocyanates have also been available for many years in the United States and achieved some commercial success as appliance finishes. 

The distribution of powder coating sales by resin type for various geographical areas is given in Table 5. The polyester—epoxy hybrids account for 50% of the European market, yet have only market share <25% in the rest of the world. Similarly, the polyester urethanes, which account for only a small market share in Europe, find significant usage in the United States andjapan. AcryUcs hold a significant share only in the Japanese market. 

One approach for ameliorating the highly brittle nature of these cements has involved the use of tougher, more ductile fillers (62,63). Another approach for improving the overall properties of traditional glass—ionomer cements involves the development of hybrid cement-composites and resin-modified cements (64—68). 

To improve the weatherabUity of epoxies, which normally chalk and yeUow, epoxy—polyester aUoys or hybrids are used. These powders with improved overbake resistance cure at temperatures as low as 130°C. They have film flexibiHty similar to epoxy resins, but their hardness is slightly decreased. Corrosion resistance is equivalent to epoxy powders in most cases, although solvent and alkaH resistance is inferior. 

For some years there has been concern at the amount of styrene vapour in workshops preparing reinforced polyester laminates. More recently this has increased interest in polyester-polyurethane hybrids and in the further development of closed moulding and resin transfer moulding techniques as well as greater use of lower styrene levels. 

Note X=in-plane 0°, Y=in-plane 90°, 2 = through thickness, V,=fibev volume fraction, M=Tnat VGCF, H=hybrid VGCF, S=short staple VGCF, P=P-55 fiber, E=cpoxy, CER=cyanate ester resin. 

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