Photopolymers exhibiting a large difference between glass transition and curing temperatures

Kloosterboer, J. G.; Lijten, G. F. C. M.

doi:10.1016/0032-3861(90)90356-4

Cited by 99 publications

(62 citation statements)

References 14 publications

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“…higher than T cure . 35 Similarly, Kloosterboer and Lijten 36 found the difference between the T g (tan For the sample cured at 23ЊC, the modulus and tan d curves appear to show two glass transitions d) and T cure to be 70ЊC for a diacrylate network.…”

Section: May Bementioning

confidence: 91%

Curing kinetics and thermal properties of vinyl ester resins

Cook

Simon

Burchill

et al. 1997

J. Appl. Polym. Sci.

158

112

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ABSTRACT:The curing kinetics of dimethacrylate-based vinyl ester resins were studied by scanning and isothermal DSC, gel time studies, and by DMTA. The rate of polymerization was raised by increased methyl ethyl ketone peroxide (MEKP) concentration but the cocatalyst, cobalt octoate, retarded the reaction rate, except at very low concentrations. By contrast, the gel time was reduced for all increases in either peroxide or cobalt concentration. This contradictory behavior was explained by a kinetic scheme in which the cobalt species play a dual role of catalyzing the formation of radicals from MEKP and of destroying the primary and polymeric radicals. The scanning DSC curves exhibited multiple peaks as observed by other workers, but in the present work, these peaks were attributed to the individual influence of temperature on each of fundamental reaction steps in the free radical polymerization. Physical aging appeared to occur during the isothermal polymerization of samples cured below the ''fully cured'' glass transition temperature (T g ). For these undercured materials, the difference between the DSC T g and the isothermal curing temperature was approximately 11ЊC. Dynamic mechanical analysis of a partially cured sample exhibited anomalous behavior caused by the reinitiation of cure of the sample during the DMTA experiment. For partially cured resins, the DSC T g increased monotonically with the degree of cure, and this dependence was fitted to an equation related to the Couchman and DiBenedetto equations.

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Section: May Bementioning

confidence: 91%

Curing kinetics and thermal properties of vinyl ester resins

Cook

Simon

Burchill

et al. 1997

J. Appl. Polym. Sci.

158

112

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“…In light of this, one would expect that even in a vitrified system increases in photoinitiator would cause increases in reaction conversion. A study has been reported that suggests vitrification favors recombination of primary radicals and, as a result, reduces the efficiency of a photoinitiator 10) . Under this set of circumstances, it is highly unlikely that small changes in photoinitiator concentration (like 2.0% to 4.0%) will cause the necessary increase in radical concentration to effect reaction propagation in our systems.…”

Section: Two Level Factorial Modelmentioning

confidence: 99%

“…Vitrification causes the mobility of unreacted polymer chains to be significantly reduced and it has been reported that reaction rates decrease to a level that is 1% of the maximum rate 10) . Even in vitrified systems, it is widely accepted that unreacted monomer/photoinitiator is capable of diffusing through the system causing further reaction conversion and transport of reactive sites by means of hydrogen abstractions 10) . In light of this, one would expect that even in a vitrified system increases in photoinitiator would cause increases in reaction conversion.…”

Section: Two Level Factorial Modelmentioning

confidence: 99%

The effects of photocrosslinking parameters on films made from mixtures of maleate and vinyl ether functional oligomers: a factorial model

Matranga

Meij

1998

Angew. Makromol. Chem.

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“…Several authors have pointed out that DSC technique monitors the polymerization rate rather than conversion and this method fail for conversion measurements in the case of very slow processes [21]. This fact can explain the broken correlation between fluorescence and DSC conversions at the final stage of polymerization as follows.…”

Section: Fluorescence Monitoring Of Multifunctional (Meth)acrylates Pmentioning

confidence: 99%

Following in situ photoinitiated polymerization of multifunctional acrylic monomers by fluorescence and photocalorimetry simultaneously

Peinado

Alonso

Salvador

et al. 2002

Polymer

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The photoinitiated polymerization of multifunctional (meth)acrylic monomers was simultaneously monitored in real time by fluorescence and differential scanning calorimetry. As the curing proceeds, the fluorescence emission changes due to an increase in the viscosity of the microenvironment. A good correlation between fluorescence intensity and degree of conversion was established by using two different fluorescent probes, each having the same fluorophore, dialkylamino derivatives of 7-nitro-2-oxa-1,3-diazol. One of the probes contains an acrylic moiety which can react with the monomers labelling the formed network. The use of the first moment of fluorescence is presented as a suitable methodology to avoid experimental fluctuations. Furthermore, the influence of the length of the spacer between the acrylic groups in the polymerization reaction kinetics and fluorescence changes has been also discussed in terms of reaction diffusion controlled termination kinetics and free volume fraction. It was concluded that the fluorescence method is a powerful tool to study the kinetics of photopolymerization of multifunctional monomers.

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Photopolymers exhibiting a large difference between glass transition and curing temperatures

Cited by 99 publications

References 14 publications

Curing kinetics and thermal properties of vinyl ester resins

Curing kinetics and thermal properties of vinyl ester resins

The effects of photocrosslinking parameters on films made from mixtures of maleate and vinyl ether functional oligomers: a factorial model

Following in situ photoinitiated polymerization of multifunctional acrylic monomers by fluorescence and photocalorimetry simultaneously

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