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Effect of cure cycle on mechanical properties of thick section fiber‐reinforced poly/thermoset moldings
Author(s) -
Mallick P. K.,
Raghupathi N.
Publication year - 1979
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760191103
Subject(s) - materials science , mold , thermosetting polymer , composite material , curing (chemistry) , compression molding , vinyl ester , molding (decorative) , thermal , transfer molding , flexural strength , glass fiber , fiber , polymer , physics , meteorology , copolymer
One of the major factors of concern in compression molding of fiber‐reinforced thermosets is the mold cycle time which directly affects the processing cost. An ideal system would be the one which cures in a relatively short time resulting in excellent mechanical and physical properties. However, in practice, a compromise has to be made between the mold cycle time and ultimate property requirements. The effects of cure cycle time, temperature, preheating and post‐cooling on mechanical properties of continuous as well as chopped glass fiber reinforced polyester and vinyl ester systems involving 1/4 to 1 in thick sections have been studied. Mold cycle time is strongly influenced by the part thickness and mold temperature. Internal heat generation due to curing reaction causes high thermal gradients across the thickness. Preheating offers advantages of reducing both the mold cycle time and the thermal gradient. The flexural and interlaminar shear strengths are strongly dependent or, the mold cycle time. Maximum strengths are obtained when the mold is opened at the instant when there is no thermal gradient across the thickness.