In this study, novel lamination techniques are introduced for the coating of fabrics in order to enhance their ballistic/needle penetration resistance properties. Pressure sensitive adhesive (PSA) was used to create flexible ballistic composite panels with ultra-high molecular weight polyethylene (UHMWPE) fabric. An increase in processing pressure from 0.1 to 8 MPa significantly improved the ballistic performance against 9 mm FMJ ammunition of UHMWPE composite. The number of layers required to stop the bullet were reduced from 45 to 22 layers after lamination without a significant increase in stiffness. The backface signature (BFS) was reduced from 19.2 mm for the 45 layer neat samples to 11.7 mm for the 25 layer laminated samples pressed at 8 MPa.
The second lamination technique used patterned thermoplastic hot film to create flexible UHMWPE composite laminates. Hexagonal patterns were cut through a heat transfer vinyl carrier sheet using a vinyl cutter and was used as a mask between the UHMWPE fabric and hot film during heat treatment in order to have the fabric coated only on those regions. The patterns had a nominal diameter of 27.9 mm with a 1 mm gap between each region. A significant improvement in the ballistic performance of UHMWPE fabric is observed after coating each individual layer with patterned hot film and 25 layers of laminated fabric were sufficient to stop a .357 magnum FMJ ammunition compared to unlaminated neat fabric which required 45 layers to stop the bullet. Patterning of the hot film did not negatively affect the ballistic performance of the composite laminates whilst increasing their flexibility in relation to using plain hot film with no patterning involved. It resulted in a 21% increase in bending angle of the 25 layer samples
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and 9.5% reduction in bending length of the single plies which both relate to greater flexibility because a higher bending angle and lower bending length correlates to more flexibility.
The same technique of patterning of hot film is used in the lamination of woven cotton fabric to enhance needle penetration resistance properties whilst maintaining the flexibility. Patterns used in this study were either hexagonal or a combination of hexagons and triangles and the nominal diameter ranged from 2.6-13.5 mm. The lamination significantly improved the 25G hypodermic needle penetration resistance of the fabric. By increasing the number of laminated fabric plies from 1 to 2, the needle resistance force increased by up to 150%. However, in comparison to just one layer, the flexibility decreased by about 12% to 26% for two and three layers, respectively. It was observed that reducing the sizes of the patterns improved the flexibility of the samples by up to 30% without compromising the needle penetration resistance. / Thesis / Master of Applied Science (MASc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/27018 |
| Date | January 2021 |
| Creators | Mudzi, Panashe |
| Contributors | Selvaganapathy, Ravi, Chan, Ching, Mechanical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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