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Composite boards from isocyanate bonded pine needles

Authors

  • M. Gupta,

    1. Polymers, Plastics and Composites Division, Central Building Research Institute, A constituent Establishment of CSIR, Roorkee 247 667, Uttarakhand, India
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  • Monika Chauhan,

    1. Polymers, Plastics and Composites Division, Central Building Research Institute, A constituent Establishment of CSIR, Roorkee 247 667, Uttarakhand, India
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  • Naseeba Khatoon,

    1. Polymers, Plastics and Composites Division, Central Building Research Institute, A constituent Establishment of CSIR, Roorkee 247 667, Uttarakhand, India
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  • B. Singh

    Corresponding author
    1. Polymers, Plastics and Composites Division, Central Building Research Institute, A constituent Establishment of CSIR, Roorkee 247 667, Uttarakhand, India
    • Polymers, Plastics and Composites Division, Central Building Research Institute, A constituent Establishment of CSIR, Roorkee 247 667, Uttarakhand, India
    Search for more papers by this author

Abstract

The effect of alkali treatment on the wettability of pine needles was assessed by contact angle measurements. The lower critical surface energy of the treated needle (42%) favors its superior wetting behavior over the control. The composite boards were prepared from these treated needle furnishes and isocyanate prepolymer resin adhesive (3–20%). The results indicate that internal bond strength, modulus of rupture, tensile strength, and screw withdrawal load increased with the increase of resin adhesive content. At lower humidity, the boards with varying resin adhesive contents exhibited 2–7% thickness swelling at equilibrium moisture content whereas at higher humidity, the thickness swelling in the boards ranged between 13–23%. Under immersed water, the composite boards swelled 2–3 times as much as the samples exposed at 98% RH. After aging, the internal bond strength of boards was reduced by 41–67% in accelerated water and 54–78% in cyclic exposure respectively. Fractographic evidences such as pulled out of needle fibers, fiber fracture and debonding, because of swelling of fibers in the aged samples could be used to explain the loss of strength. The screw withdrawal load of the high resin adhesive content boards (20%) was comparable with the natural wood. The developed composite board satisfies the requirements of Standard Specification: IS: 3087-2005 / EN 312-2003. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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