Abstract

We describe a novel noninvasive optical technique to monitor the refractive-index variation in an epoxy-based resin that is due to the polymerization process. This kind of resin is widely used in polymer matrix composites. It is well known that the process of fabricating a thermoset-based composite involves mass and heat transfer coupled with irreversible chemical reactions that induce physical changes. To improve the quality and the reliability of these materials, monitoring the cure and optimization of the manufacturing process are of key importance. We discuss the basic operating principles of an optical system based on angle deflection measurements and present typical cure-monitoring results obtained from optical characterization. The method provides a flexible, high-sensitivity, material-independent, low-cost, noninvasive tool for monitoring real-time refractive-index variation.

© 2000 Optical Society of America

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References

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  1. A. Maffezolli, J. M. Kenny, A. Trevisano, L. Torre, L. Nicolais, “Process modeling of thermoset based composites,” Adv. Mater. 16B, 747–753 (1993).
  2. J. M. Kenny, A. Apicella, L. Nicolais, “A model for the thermal and chemoreological behavior of thermosets. 1. Processing of epoxy based composites,” Polym. Eng. Sci. 29, 973–983 (1989).
    [CrossRef]
  3. L. A. Berglund, J. M. Kenny, “Processing science for high performance thermoset composites,” SMPTE J. 27, 271–280 (1991).
  4. Y. M. Liu, C. Ganesh, J. P. H. Steele, J. E. Jones, “Fiber optic sensor development for real-time in-situ epoxy cure monitoring,” J. Compos. Mater. 31, 87–102 (1997).
    [CrossRef]
  5. P. A. Crosby, G. R. Powell, G. F. Fernando, D. N. Waters, C. M. France, R. C. Spooncer, “A comparative study of optical fiber cure monitoring methods,” in Smart Structures and Materials 1997: Smart Sensing, Processing, Instrumentation, O. R. Claus, ed., Proc. SPIE3042, 157–172 (1997).
  6. M. A. Afromowitz, K. Y. Lam, “The optical properties of curing epoxies and application to the fiber-optic cure sensor,” Sens. Actuators A 21–23, 1107–1110 (1990).
  7. M. A. Afromowitz, “Fiber optic polymer cure sensor,” J. Lightwave Technol. 6, 1591–1594 (1988).
    [CrossRef]
  8. M. A. Afromowitz, K. Y. Lam, “Fiber optic cure sensor for thermoset composites,” in Fiber Optic Smart Structures and Skins, E. Udd, ed., Proc. SPIE986, 135–138 (1988).
    [CrossRef]
  9. M. A. Afromowitz, K. Y. Lam, “Fiber-optic epoxi composite cure sensor. I. Dependence of refractive index of an autocatalytic reaction epoxy system at 850 nm on temperature and extent of cure,” Appl. Opt. 34, 5635–5638 (1995).
    [CrossRef]
  10. M. A. Afromowitz, K. Y. Lam, “Fiber-optic epoxy composite cure sensor. II. Performance characteristics,” Appl. Opt. 34, 5639–5643 (1995).
    [CrossRef] [PubMed]

1997 (1)

Y. M. Liu, C. Ganesh, J. P. H. Steele, J. E. Jones, “Fiber optic sensor development for real-time in-situ epoxy cure monitoring,” J. Compos. Mater. 31, 87–102 (1997).
[CrossRef]

1995 (2)

1993 (1)

A. Maffezolli, J. M. Kenny, A. Trevisano, L. Torre, L. Nicolais, “Process modeling of thermoset based composites,” Adv. Mater. 16B, 747–753 (1993).

1991 (1)

L. A. Berglund, J. M. Kenny, “Processing science for high performance thermoset composites,” SMPTE J. 27, 271–280 (1991).

1990 (1)

M. A. Afromowitz, K. Y. Lam, “The optical properties of curing epoxies and application to the fiber-optic cure sensor,” Sens. Actuators A 21–23, 1107–1110 (1990).

1989 (1)

J. M. Kenny, A. Apicella, L. Nicolais, “A model for the thermal and chemoreological behavior of thermosets. 1. Processing of epoxy based composites,” Polym. Eng. Sci. 29, 973–983 (1989).
[CrossRef]

1988 (1)

M. A. Afromowitz, “Fiber optic polymer cure sensor,” J. Lightwave Technol. 6, 1591–1594 (1988).
[CrossRef]

Afromowitz, M. A.

M. A. Afromowitz, K. Y. Lam, “Fiber-optic epoxi composite cure sensor. I. Dependence of refractive index of an autocatalytic reaction epoxy system at 850 nm on temperature and extent of cure,” Appl. Opt. 34, 5635–5638 (1995).
[CrossRef]

M. A. Afromowitz, K. Y. Lam, “Fiber-optic epoxy composite cure sensor. II. Performance characteristics,” Appl. Opt. 34, 5639–5643 (1995).
[CrossRef] [PubMed]

M. A. Afromowitz, K. Y. Lam, “The optical properties of curing epoxies and application to the fiber-optic cure sensor,” Sens. Actuators A 21–23, 1107–1110 (1990).

M. A. Afromowitz, “Fiber optic polymer cure sensor,” J. Lightwave Technol. 6, 1591–1594 (1988).
[CrossRef]

M. A. Afromowitz, K. Y. Lam, “Fiber optic cure sensor for thermoset composites,” in Fiber Optic Smart Structures and Skins, E. Udd, ed., Proc. SPIE986, 135–138 (1988).
[CrossRef]

Apicella, A.

J. M. Kenny, A. Apicella, L. Nicolais, “A model for the thermal and chemoreological behavior of thermosets. 1. Processing of epoxy based composites,” Polym. Eng. Sci. 29, 973–983 (1989).
[CrossRef]

Berglund, L. A.

L. A. Berglund, J. M. Kenny, “Processing science for high performance thermoset composites,” SMPTE J. 27, 271–280 (1991).

Crosby, P. A.

P. A. Crosby, G. R. Powell, G. F. Fernando, D. N. Waters, C. M. France, R. C. Spooncer, “A comparative study of optical fiber cure monitoring methods,” in Smart Structures and Materials 1997: Smart Sensing, Processing, Instrumentation, O. R. Claus, ed., Proc. SPIE3042, 157–172 (1997).

Fernando, G. F.

P. A. Crosby, G. R. Powell, G. F. Fernando, D. N. Waters, C. M. France, R. C. Spooncer, “A comparative study of optical fiber cure monitoring methods,” in Smart Structures and Materials 1997: Smart Sensing, Processing, Instrumentation, O. R. Claus, ed., Proc. SPIE3042, 157–172 (1997).

France, C. M.

P. A. Crosby, G. R. Powell, G. F. Fernando, D. N. Waters, C. M. France, R. C. Spooncer, “A comparative study of optical fiber cure monitoring methods,” in Smart Structures and Materials 1997: Smart Sensing, Processing, Instrumentation, O. R. Claus, ed., Proc. SPIE3042, 157–172 (1997).

Ganesh, C.

Y. M. Liu, C. Ganesh, J. P. H. Steele, J. E. Jones, “Fiber optic sensor development for real-time in-situ epoxy cure monitoring,” J. Compos. Mater. 31, 87–102 (1997).
[CrossRef]

Jones, J. E.

Y. M. Liu, C. Ganesh, J. P. H. Steele, J. E. Jones, “Fiber optic sensor development for real-time in-situ epoxy cure monitoring,” J. Compos. Mater. 31, 87–102 (1997).
[CrossRef]

Kenny, J. M.

A. Maffezolli, J. M. Kenny, A. Trevisano, L. Torre, L. Nicolais, “Process modeling of thermoset based composites,” Adv. Mater. 16B, 747–753 (1993).

L. A. Berglund, J. M. Kenny, “Processing science for high performance thermoset composites,” SMPTE J. 27, 271–280 (1991).

J. M. Kenny, A. Apicella, L. Nicolais, “A model for the thermal and chemoreological behavior of thermosets. 1. Processing of epoxy based composites,” Polym. Eng. Sci. 29, 973–983 (1989).
[CrossRef]

Lam, K. Y.

M. A. Afromowitz, K. Y. Lam, “Fiber-optic epoxi composite cure sensor. I. Dependence of refractive index of an autocatalytic reaction epoxy system at 850 nm on temperature and extent of cure,” Appl. Opt. 34, 5635–5638 (1995).
[CrossRef]

M. A. Afromowitz, K. Y. Lam, “Fiber-optic epoxy composite cure sensor. II. Performance characteristics,” Appl. Opt. 34, 5639–5643 (1995).
[CrossRef] [PubMed]

M. A. Afromowitz, K. Y. Lam, “The optical properties of curing epoxies and application to the fiber-optic cure sensor,” Sens. Actuators A 21–23, 1107–1110 (1990).

M. A. Afromowitz, K. Y. Lam, “Fiber optic cure sensor for thermoset composites,” in Fiber Optic Smart Structures and Skins, E. Udd, ed., Proc. SPIE986, 135–138 (1988).
[CrossRef]

Liu, Y. M.

Y. M. Liu, C. Ganesh, J. P. H. Steele, J. E. Jones, “Fiber optic sensor development for real-time in-situ epoxy cure monitoring,” J. Compos. Mater. 31, 87–102 (1997).
[CrossRef]

Maffezolli, A.

A. Maffezolli, J. M. Kenny, A. Trevisano, L. Torre, L. Nicolais, “Process modeling of thermoset based composites,” Adv. Mater. 16B, 747–753 (1993).

Nicolais, L.

A. Maffezolli, J. M. Kenny, A. Trevisano, L. Torre, L. Nicolais, “Process modeling of thermoset based composites,” Adv. Mater. 16B, 747–753 (1993).

J. M. Kenny, A. Apicella, L. Nicolais, “A model for the thermal and chemoreological behavior of thermosets. 1. Processing of epoxy based composites,” Polym. Eng. Sci. 29, 973–983 (1989).
[CrossRef]

Powell, G. R.

P. A. Crosby, G. R. Powell, G. F. Fernando, D. N. Waters, C. M. France, R. C. Spooncer, “A comparative study of optical fiber cure monitoring methods,” in Smart Structures and Materials 1997: Smart Sensing, Processing, Instrumentation, O. R. Claus, ed., Proc. SPIE3042, 157–172 (1997).

Spooncer, R. C.

P. A. Crosby, G. R. Powell, G. F. Fernando, D. N. Waters, C. M. France, R. C. Spooncer, “A comparative study of optical fiber cure monitoring methods,” in Smart Structures and Materials 1997: Smart Sensing, Processing, Instrumentation, O. R. Claus, ed., Proc. SPIE3042, 157–172 (1997).

Steele, J. P. H.

Y. M. Liu, C. Ganesh, J. P. H. Steele, J. E. Jones, “Fiber optic sensor development for real-time in-situ epoxy cure monitoring,” J. Compos. Mater. 31, 87–102 (1997).
[CrossRef]

Torre, L.

A. Maffezolli, J. M. Kenny, A. Trevisano, L. Torre, L. Nicolais, “Process modeling of thermoset based composites,” Adv. Mater. 16B, 747–753 (1993).

Trevisano, A.

A. Maffezolli, J. M. Kenny, A. Trevisano, L. Torre, L. Nicolais, “Process modeling of thermoset based composites,” Adv. Mater. 16B, 747–753 (1993).

Waters, D. N.

P. A. Crosby, G. R. Powell, G. F. Fernando, D. N. Waters, C. M. France, R. C. Spooncer, “A comparative study of optical fiber cure monitoring methods,” in Smart Structures and Materials 1997: Smart Sensing, Processing, Instrumentation, O. R. Claus, ed., Proc. SPIE3042, 157–172 (1997).

Adv. Mater. (1)

A. Maffezolli, J. M. Kenny, A. Trevisano, L. Torre, L. Nicolais, “Process modeling of thermoset based composites,” Adv. Mater. 16B, 747–753 (1993).

Appl. Opt. (2)

J. Compos. Mater. (1)

Y. M. Liu, C. Ganesh, J. P. H. Steele, J. E. Jones, “Fiber optic sensor development for real-time in-situ epoxy cure monitoring,” J. Compos. Mater. 31, 87–102 (1997).
[CrossRef]

J. Lightwave Technol. (1)

M. A. Afromowitz, “Fiber optic polymer cure sensor,” J. Lightwave Technol. 6, 1591–1594 (1988).
[CrossRef]

Polym. Eng. Sci. (1)

J. M. Kenny, A. Apicella, L. Nicolais, “A model for the thermal and chemoreological behavior of thermosets. 1. Processing of epoxy based composites,” Polym. Eng. Sci. 29, 973–983 (1989).
[CrossRef]

Sens. Actuators A (1)

M. A. Afromowitz, K. Y. Lam, “The optical properties of curing epoxies and application to the fiber-optic cure sensor,” Sens. Actuators A 21–23, 1107–1110 (1990).

SMPTE J. (1)

L. A. Berglund, J. M. Kenny, “Processing science for high performance thermoset composites,” SMPTE J. 27, 271–280 (1991).

Other (2)

P. A. Crosby, G. R. Powell, G. F. Fernando, D. N. Waters, C. M. France, R. C. Spooncer, “A comparative study of optical fiber cure monitoring methods,” in Smart Structures and Materials 1997: Smart Sensing, Processing, Instrumentation, O. R. Claus, ed., Proc. SPIE3042, 157–172 (1997).

M. A. Afromowitz, K. Y. Lam, “Fiber optic cure sensor for thermoset composites,” in Fiber Optic Smart Structures and Skins, E. Udd, ed., Proc. SPIE986, 135–138 (1988).
[CrossRef]

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Figures (7)

Fig. 1
Fig. 1

Basic configuration for refractive-index measurements.

Fig. 2
Fig. 2

Shift observed in the camera in the case of a height change during refractive-index monitoring.

Fig. 3
Fig. 3

Laser spot viewed with the CID camera (a) in the absence of the resin sample and (b) in the presence of the resin.

Fig. 4
Fig. 4

Conversion versus time during an isothermal scan at 40 °C.

Fig. 5
Fig. 5

Epoxy’s refractive index during an isothermal scan at 40 °C.

Fig. 6
Fig. 6

Epoxy’s refractive index during a dynamic cure cycle.

Fig. 7
Fig. 7

Neat resin’s refractive index versus temperature.

Equations (10)

Equations on this page are rendered with MathJax. Learn more.

sinϑu=npsinϑp.
ϑp=2ϑd,
ϑdmax=arcsin1/npmax/2.
ΔY=ΔYn+ΔYδ=doΔϑ+δkg.
δ=δepo+δapp-δα=γepoLepo+γappLappΔT-βαLepoΔα,
δ<γappLtotΔT-βαLepoΔα.
ΔYn=doϑnnT ΔT+nα Δα=dokϑηTΔT+ηαΔα.
do  kgγappLtot-βαLepoα˙νkϑηT+ηαα˙ν,
doLepo  kgβαkϑηα.
doLtot  kgγappkϑηT.

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