Determination of tensile strength of paraffin waxes

Asadchii, O. G.; Votlokhin, B. Z.; Bogdanov, N. F.; Gladyshev, V. P.

doi:10.1007/bf00723880

Cited by 1 publication

(3 citation statements)

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“…which is plotted in figure 4 as a function of porous structure size. It is obvious that when ligament sizes are above ∼70 nm, the mean tensile stress in paraffin is below 2 MPa, which is comparable to the tensile strength of bulk paraffin [19,20]. In contrast, as the ligament size decreases, the tensile stress in paraffin increases rapidly, reaching up to 15.9 MPa at L∼20 nm.…”

Section: Resultsmentioning

confidence: 94%

“…Apparently, the maximum tensile stress developed in paraffin, σ paraffin , could not exceed the tensile yield strength of paraffin, which is approximately 1.5 MPa for bulk paraffin [19,20]. Otherwise, the voids or cracks would be formed in paraffin to compensate the further volume changes, if the solid framework is rigid enough to withstand the contraction.…”

Section: Resultsmentioning

confidence: 99%

“…Most of the previous metal/paraffin composites were developed on the basis of micro-porous metals with relatively large (μm to mm scale) pore structure sizes, in which the metal framework does not necessarily expand/ shrink simultaneously with the paraffin during heating/ cooling [17,18]. Instead, the volume contraction of paraffin during cooling can be compensated by forming micro-cracks or voids in paraffin confined in pore space, due to its low tensile strength [19,20] if the metal framework is rigid. These metal/paraffin mico-composites may be excellent thermal managing materials, but not good candidates for high-performance actuation.…”

Section: Introductionmentioning

confidence: 99%

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Sealing-free fast-response paraffin/nanoporous gold hybrid actuator

Jin

2017

Nanotechnology

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Paraffin-based actuators can deliver large actuation strokes and high actuation stress, but often suffer from a low response rate and leaking problems. Here, we report a new paraffin/metal hybrid actuator, which was fabricated by infiltrating nanoporous gold with paraffin. It exhibits a fast actuation rate owing to the high thermal conductivity of the inter-connected metal phase, and requires no external sealing because liquid paraffin can be well confined in nanoscale channels, due to the large capillarity. We found that in this hybrid actuator, the stress generated by actuation is negligibly small when the characteristic size of the nanoporous gold (L) is above ∼70 nm, and increases dramatically with a decreasing size when L < ∼70 nm. The large actuation stress in samples with L < ∼70 nm is ascribed to a 'smaller is stronger' effect in paraffin wax-the paraffin in smaller pores can sustain larger tensile stress, and thus the contraction of paraffin during cooling can be translated into larger compression stress and strain energy in a metal framework, leading to a larger actuation stress and energy. We also demonstrate that complex actuation motions can be achieved by incorporating hierarchical-structured nanoporous metal with paraffin.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%