Insulation Type: XL-Poly alkene
Trade Names(the following are common tradenames used for XL-Poly alkene insulation)
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| Example with XL poly (propylene) |
Aircraft on which XL-Poly alkene has been used/found- A-10 (No dates available)
- Boeing 747 (No dates available)
- Cessna 400 Series (No dates available)
- Cessna 500 Series (No dates available)
- DC-9 (1968 - 1977)
*Note: Some of the older aircraft types of insulation may have replaced by the original wire. The listings of aircraft are not complete, especially with those special uses, e.g., engine areas, electronic boxes, etc.
Mil Specs and other Standards using XL-Poly alkene- BMS13-38 (Boeing)
- DSP-26
- MIL-W-16878/35
- MIL-W-22759/36 ((XL poly alkene only))
- MIL-W-22759/37 ((XL poly alkene only))
- MIL-W-22759/38 ((XL poly alkene only))
- MIL-W-22759/39 ((XL poly alkene only))
- MIL-W-22759/40 ((XL poly alkene only))
- MIL-W-81044/1
- MIL-W-81044/2
- MIL-W-81044/3
- MIL-W-81044/4
- MIL-W-81044/5
- MIL-W-81044/6
- MIL-W-81044/7
- MIL-W-81044/8
- MIL-W-81044/9
- MIL-W-81044/10
- MIL-W-81044/11
- MIL-W-81044/12
- MIL-W-81044/13
- MIL-W-81044/14
- MIL-W-81044/15
Advantages: Relatively inexpensive by itself
With XL PVDF
oBecause dual extrusion which is fused by sintering, it combines excellent abrasion and cut-through resistance of PVDF with poly-alkene for greater flexibility and improved heat resistance
oCross-linked PVDF reduces possible decomposition with the loss of HF
oNot affected with exposure to normally expected fluids
Disadvantages: PVDF by itself is stiff
Somewhat lower temperature ratings, e.g., 150o C maximum
Heavy - 5.5 pounds per 1000 feet (8.1 kg/km) for AWG 20
Relative thicker than some other wire types -70 mils (1.78 mm) for AWG 20 wire
Small weight loss over time from decomposition (loss of HF) - 1 % in 15 yr (estimated)
Other Information: When used in aircraft wiring, it appears that poly alkenes are cross- linked and often with XL-PVDF
XL Poly alkene is used mainly as the primary insulation under an outer jacket of XL-PVDF
Anti-oxidants, plasticizers, and flame retardants often are added to poly alkenes to improve long term properties
With a temperature rating of 150 C, the poly alkene is from a precursor that possibly has several carbon atoms
-For example poly (4-methyl-pentene-1) with a melting point of about 230 C
-However this material has a glass transition at about room temperature
Cross linking usually is done by high energy electrons
oIn a Raychem patent the detailed experimental results used poly (ethylene), but in certain spots the term poly alkene was employed
- a Raychem patent it was claimed that cross linking improved some thermal properties
- a Raychem patent it was claimed that flame retardants (a few percent by weight) improved burning characteristics especially with XL-PVDF
Cross linking also is done by gamma rays and chemical reactions
Poly alkene may be a mixture of several alkenes precursors since the term is general
XL PE has temperature ratings from about 90 to 150 C for various wires, but in MIL-W-16878/14 through /16 the specification is 125 C