Thermal Expansion Coefficient of Unidirectional High-Strength Polyethylene Fiber Reinforced Plastics at Low Temperature

Abstract

High-strength polyethylene fiber (Dyneema Õ , DF) has a negative linear thermal expansion coefficient in the direction of the fiber. Thermal expansion coefficients of fiber-reinforced plastics are of important applications in cryogenic use. The purpose of this study is to construct the engineering technology for the thermal strain of DF reinforced plastics (DFRP) for cryogenic engineering. In this study, we investigate the thermal expansion coefficient of unidirectional high-strength DF reinforced plastics (UD-DFRP) in which DFs with different tensile moduli (15-134 GPa) and thermal expansion coefficients are used. Furthermore, using the thermal expansion coefficient and tensile modulus of each DF fiber and the matrix resin, the thermal expansion coefficients of the DFRPs are estimated by the rule of mixtures and are compared with the measured values. The results indicate that the thermal expansion coefficient of UD-DFRP behaves in a similar way to that expected from calculations based on the rule of mixtures. In addition, relationships concerning the difference between the calculated and measured values, the difference in the thermal expansion coefficient of the fiber and the resin, and the surface treatment of the fiber (adhesivity), as well as the diameter of the fiber (the area of the interfacial bonding) are studied. The results show that all of these influence the thermal expansion coefficient of UD-DFRP. The design of negative thermal expansion coefficient of UD-DFRP is established.

Interfacial evaluation of epoxy/carbon nanofiber nanocomposite reinforced with glycidyl methacrylate treated UHMWPE fiber

“…It could be also seen that the UHMWPE fiber has a negative linear thermal expansion coefficient in the fiber direction. The linear thermal expansion coefficient of GMA‐treated fibers could be estimated from the relation between the thermal expansion coefficients and tensile modulus of UHMWPE fiber . The CTE of the neat epoxy resin and CNF/epoxy specimens (at three different weight fractions of CNFs) were calculated to investigate the CNFs effects on CTE of epoxy using eqs.…”

Defect controlled transverse compressive strength of polyethylene fiber laminates

“…These cracks resulted in a voided region volume fraction of about 3% existing throughout the composite. We identify these flaws as tunnel cracks (Ho and Suo, 1993;Xia et al, 1993) that form upon cooling after consolidation, as a result of the substantial anisotropy in thermal expansion coefficient of a ply (Barrera et al, 2005;Yamanaka et al, 2007). The negative coefficient of thermal expansion in the fiber direction results in thermal elongation of the ply during cooling while the substantial positive coefficient of thermal expansion in the transverse directions (combined with a very low transverse tensile strength of the ply) results in thermal contraction (and fracture) upon cooling.…”

Dynamic tensile strength of organic fiber-reinforced epoxy micro-composites

“…Moreover the axial CTE of the fibers is negative at the temperature interval from 20 to 150°C [31], at which the curing of the epoxy matrix of the composites is usually conducted. The negative axial CTE of Kevlar fibers in this temperature range is of about À25 Â 10 À6 K À1 [32] while the CTE of UHMWPE fibers is of about À12 Â 10 À6 K À1 [33], two times lower. The ratio between CTEs of the two materials demonstrates an opposite trend.…”