Polyolefin film–reinforced composites for personal protection

doi:10.1016/B978-1-78242-461-1.00013-3

Advanced Fibrous Composite Materials for Ballistic Protection

2016, Pages 389-408

https://doi.org/10.1016/B978-1-78242-461-1.00013-3 Get rights and content

Abstract

This chapter describes the use of oriented films of polyolefins in ballistic protective applications. The history of their use in ballistic protective applications is briefly discussed, from early efforts in World War II, through development of stretched melt-blown tape-reinforced polyolefins in the Vietnam War, through solid-state extrusion (SSE) and then SSE with two stage drawing in the 21st century. Current SSE film reinforcements are summarised, and armour performance in ballistic impact is described compared to benchmark materials. Advantages that may be inherent to film-reinforced composites are discussed, including buoyancy, a unique combination of high perforation resistance and low dynamic deflection, high cut resistance and relative ease in attachment. The chapter concludes with suggestions for the heretofore unexplained observation that polyolefin film–reinforced armour composites offer protection per weight far beyond than expected by their specific axial strength, using rules of thumb developed for fibre-reinforced armour composites.

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Cited by (9)

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Improvement of the protective performance and processing technique has always been the research focus of lightweight bulletproof composites. To explore the ballistic characteristics of newly developed ultra-high molecular weight polyethylene (UHMWPE) film laminates, field firing tests of the 10-, 20- and 30-mm-thick film laminates under shots of 7.62 × 39 mm steel core bullets were conducted. The deformation process, final failure state, and penetration cross-section of the film laminates were analyzed and discussed. The results showed that without considering the deformation degree, the ballistic performances of the film laminates were significantly superior to those of the traditional UHMWPE fibre laminates. Weak interlaminar mechanical property was the key to the ballistic characteristics of the film laminates. The multi-stage penetration mechanisms of the film laminates were evidently different from those of the fibre laminates, indicating the variation in ballistic analytical method. Finally, the respective recommended ballistic protection applications of the film laminates with different thicknesses were proposed.
Effects of spacing and ply blocking on the ballistic resistance of UHMWPE laminates
2021, International Journal of Impact Engineering
Citation Excerpt :
Some commercial gel-spun fibers/tapes are Honeywell Spectra® (900,1000,3000, WO2011/1137045) and DSM Dyneema® (SK75, SK76) [9]. Examples of solid-state extrusion tapes are Teijin Endumax® [10], Armour Holdings Tensylon® HT, BAE Systems Tensylon® HS and Dupond TensylonTM HM [11]. The solid-state tape has inherently lower strength than the gel-spun fiber/tape due to its grain boundaries.
It is commonly claimed that ultra-high molecular weight polyethylene (UHMWPE) laminates offer high energy absorption during projectile impact with a cross-ply configuration. In this study, we explored alternative configurations with the aim of achieving better ballistic resistance than that of the cross-ply architecture. The UHMWPE laminates were fabricated from Endumax® cross-ply SHIELD XF23 using a hot press machine and material properties were obtain from Endumax® unidirectional (UD) tape TA23 coupon specimens. A solid steel sphere was used as the projectile. It was found that thinner laminates have higher the specific ballistic limit suggesting that it is more effective to deploy multiple stacks of thin laminated panels spaced apart than to bond all the laminas to form a single thick laminate. Experiments confirmed that while the multiple laminate systems always outperformed a single laminate comprising the same number of laminas, it was also best not to space the laminates apart. When simply stacked without spacing, the multi-laminate arrangement significantly enhanced the ballistic performance (about 10% increase in ballistic limit over the single panel). Adjacent laminates in the multi-laminate system were then rotated 45^o relative to each other and then bonded together to form a single laminate with multiple blocks of similarly oriented laminas. This ply block configuration also had higher ballistic limit than the single cross-ply laminate for thin laminates but showed no advantage for thick laminates.
The effect of in-plane shear properties on the ballistic performance of polyethylene composites
2020, International Journal of Impact Engineering
Citation Excerpt :
To test the hypothesis that back face deformation is influenced by the in-plane shear properties of a material, HB 210 and HB 212 were shot at 220 m/s alongside the Tensylon 30A material. Tensylon 30A features an in-plane shear stiffness 20 times higher than fiber UHMWPE materials [20] and higher flow stress (as shown in Figure 16), but a significantly lower modulus and strength in the principal directions [20], giving a lower limit velocity [7] (and thus, the reduced test velocity). As expected, the Tensylon demonstrates significantly lower BFD and the correspondingly smaller shear strains (as shown in Figure 17c and f) when compared to both fiber reinforced systems (Fig. 17a, b, d, e), whose trend continues at the reduced velocity.
Using developed experimental and analytical methods for in-plane shear characterization of quasi-statically loaded polyethylene (PE) laminates, this work evaluates the effect of the in-plane shear behavior has on ballistic performance (limit velocity and back face deflection). As in-plane shear is a matrix-dominated phenomena and processing pressure is known to noticeably influence the shear properties of polyethylene composites, the matrix materials and processing conditions are varied in order to probe an array of configurations. The in-plane shear properties are assessed through quasi-static tensile testing of laminates with [±45°] orientation and the ballistic performance is evaluated using a laboratory gas gun and high speed DIC. It is found that the in-plane shear strain for the more compliant HB 212 material is twice that of the HB 210 material during a ballistic event, which corresponds to the 5% increase in limit velocity of HB 212 over HB 210. The source of the shear deformation in PE materials is fiber rotation as evidenced by the quasi static tests.
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Abstract