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Photoinitiated radical polymerization

Most of the radical-type photoinitiators used in UV-curable adhesives consist of aromatic ketones that are known to generate free radicals upon UV-exposure, either by homolytical cleavage of C—C bonds or by hydrogen abstraction from a H-donor molecule. [Pg.222]

Chart 10.1 Chemical formula of radical-type photoinitiators. [Pg.223]

Because of growing molecular mobility restrictions during the light-induced liquid to solid phase change, polymerization stops when vitrification occurs, which leads to an incompletely cured glassy material. High degrees of polymerization (close to [Pg.223]

One of the problems encountered in photoinitiated radical polymerization is the inhibitory effect of [Pg.224]

To cure thin coatings in contact with air, it is, therefore, necessary to work under intense illumination to consume rapidly the O2 dissolved in the sample and shorten the exposure time during which atmospheric oxygen diffuses into the coating. This is not a problem anymore in adhesive applications that are performed under oxygen diffusion-free conditions (laminates). After a short induction period during which the dissolved O2 is consumed by the initiator radicals, the polymerization of the acrylate double bond proceeds as fast in the laminated sample as in an inert atmosphere and much faster than for a coating, as shown in Fig. 10.2 for a PUA resin. [Pg.224]


The polymerization reaction was found to develop both faster and more extensively as IQ was increased, up to a certain value above which identical RTIR curves were recorded. Consequently, the (Rp)max value reaches an upper limit, as shown in Figure 5 where (Rp)max was plotted versus Iq on a logarithmic scale. The slope of the straight line obtained at low light intensities, 0.55, is close to the 0.5 value expected for a photoinitiated radical polymerization involving bimolecular termination reactions. [Pg.67]

G. Hizal, S.E. Emiroglu, and Y. Yagci, Photoinitiated radical polymerization using charge transfer complex of TV-ethoxy-p-cyano-pyridinium salt and 1,2,4-trimethoxybenzene. Polym. Int. 1998, 47(4), 391-392. [Pg.474]

Photoinitiated Radical Polymerization Employed in Negative Resist Systems... [Pg.257]

Following the approach of Reiser, we present an overview of the photochemistry of photopolymerization. In general, photoinitiated radical polymerization can be described by the following reaction sequence, where I stands for the initiator, and M for the monomer " ... [Pg.257]

Polyamic acids are useful resists especially when containing 2,2 -dinitrodi-phenylmethane segments, while a Ti sapphire laser has been found to be effective for 3D curing and microfabrication. On a theoretical note, a direct correlation has been found between the calculated Boltzmann-averaged dipole moment and the measured maximum rate of photoinitiated radical polymerization of acrylic monomers. ... [Pg.239]

The reaction mechanism for a classical photoinitiated radical polymerization is shown in Scheme 3. The first step is the initiation reaction where the initiator decays into primary radicals with light exposure, which then react with carbon-carbon double bonds on the monomer. The rate of initiation (i i) is directly proportional to the light intensity (/q), initiator concentration ([/]), molar absorptivity (e), efficiency (/), and quantum yield of initiation (initiating species produced per absorbed photon. [Pg.414]

Lastly, the process and polymers produced by onium salt photoinitiated cationic polymerizations are eminently useful. Like the corresponding photoinitiated radical polymerizations which they complement, these cationic systems will find a wide range of applications where polymerization speed and economy of energy utilization are of prime concern. [Pg.360]

In conclusion, reviewing the literature and experimental material obtained from stationary photoinitiated radical polymerization of bifunctional (meth)acrylates in bulk allowed us to obtain the kinetic equation describing the process at all depths of conversion. A mechanism of 3-D polymerization combining the kinetic schemes of homophaseous and heterophaseous processes has been proposed on the basis of the microheterogeneous model and also effective rate constants of these processes have been estimated. [Pg.207]

Finally, it was thus interesting to investigate the possibility to use a suitable cyclodextrin complexed photoinitiator for initiation of pol5mierization in aqueous medium. In comparison to the thermal polymerization, the main advantage of the photoinitiated radical polymerization is the high efficiency and the reduced energy consumption. [Pg.2048]

Decker, C. and Decker, D., Photoinitiated radical polymerization of vinyl-ether-maleate systems. Polymer, 1997, 38, 2229-2237. [Pg.336]

Sturm, D. Muller, R. Rath, M.-J. Photoinitiated Radical Polymerization of Liquid Monomers in Microgravity, Vlllth European Symposium on Materials and Fluid Sciences in Microgravity, 1992, 895-899. [Pg.14]

SCH 15] Schmitz C., Halbhuber A., Strehmel B., Mechanishc aspects of photoinitiated radical polymerization in the near infrared applying LED und laser... [Pg.248]

Nese A, Sen S, Tasdelen MA, Nugay N, Yagci Y (2006) Clay-PMMA nanocomposites by photoinitiated radical polymerization using intercalated phenacyl pyridinium salt initiators. Macromol Chem Phys 207(9) 820-826... [Pg.337]

In a similar manner, extended-chain oligomeric polyesters, polyethers, and poly(dimethylsiloxane)s have been fitted with acrylate or methacrylate functional groups, and these materials find a multitude of practical uses such as UV-curable coatings and adhesives. The photoinitiated radical polymerizations of acrylic monomers and oligomers proceed very rapidly in the... [Pg.927]


See other pages where Photoinitiated radical polymerization is mentioned: [Pg.69]    [Pg.606]    [Pg.112]    [Pg.55]    [Pg.896]    [Pg.566]    [Pg.919]    [Pg.924]    [Pg.949]    [Pg.222]    [Pg.138]   
See also in sourсe #XX -- [ Pg.896 ]




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