Polymer impregnation, effects

SC CO2 used as a carrier of drug molecules into a polymer matrix has a number of advantages such as the plasticizing ability of CO2 (based on specific interactions between CO2 and polymer moieties), which both enhances the diffusion rates of drug molecules into the polymer and facilitates solvent removal. Polymer plasticization is accompanied by the swelling of the polymer matrix, with a concomitant increase in the free volume of the polymer. Moreover, SC CO2 can reduce the melting temperature of semicrystalline polymers. These effects are crucial to the impregnation and modification of polymeric materials. 

The use of fiber-reinforced polymer (FRP) composite materials in the reinforcement of concrete structures has shown important results. These interventions are based on the application of carbon fiber, glass, or aramid impregnated with thermosetting polymers. The effectiveness of these interventions is demonstrated both by extensive research in the laboratory and by applications to existing structures. 

Polymer Impregnated Concrete (PIC) obtained with hardened ordinary concretes, which are dried and then permeated with monomers of sufficient viscosity by vacuum or monomer displacement and pressure. Then, in-situ polymerization of the monomer is carried on by radiation, heating or chemical initiation. As an effect, a large part of the voids and pores is filled with polymer, which forms a continuous reinforcing network. 

Table 4. Steady-state Rate Constants, Initiator Distributions, Monomer and Polymer Impregnation Results, and Effect of Ground Leather on Polymerization Rate... 

Another approach to the use of polymers in a cementitious matrix was based on polymer impregnation. This was studied in conjunction with a light-weight GRC system, inwhichflyash cenospheres of low density were used [133]. Impregnation with methyl methacrylate was effective in improving the initial properties as well as the long-term performance. 

Figure 12.31 Effect of polymer impregnation on the stress-strain curve of carbon fibre reinforced cement (after Akihama et al. [i40]).

In 1968 the Monsanto Company announced the availability of novel soluble low molecular weight polyphenylene resins. These may be used to impregnate asbestos or carbon fibre and then cross-linked to produce heat-resistant laminates. The basic patent (BP 1037111) indicates that these resins are prepared by heating aromatic sulphonyl halides (e.g. benzene-1,3-disulphonyl dichloride) with aromatic compounds having replaceable nuclear hydrogen (e.g. bisphenoxy-benzenes, sexiphenyl and diphenyl ether). Copper halides are effective catalysts. The molecular weight is limited initially by a deficiency in one component. This is added later with further catalyst to cure the polymer. 

Hron P. Hydrophilisation of silicone rubber for medical applications. Polym Int, 2003, 52, 1531-1539. Tcholakian RK and Raad. Durability of anti-infective effect of long term silicone sheath catheters impregnated with antimicrobial agents. Antimicrob Agents Chemother, 2001, 45(7), 1990-1993. 

Domier has developed a production route for continuous fiber-reinforced ceramics based on the impregnation and pyrolysis of Si-polymers. This process is related to the manufacturing of fiber-reinforced plastics and allows the cost-effective production of large and complex CMC-structures. 

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