Mechanical and Puncture Resistance Property of Inflaming-Retarding
Fiber Composite
Jia-Horng Lin
1, 2, 3, Ting-Ting Li
4, b, Ying-Hsuan Hsu
1,
Ying-Huei Shih
1and
Ching-Wen Lou
5, a1Laboratory of Fiber Application and Manufacturing, Department of Fiber and Composite Materials,
Feng Chia University, Taichung City 40724, Taiwan.
2School of Chinese Medicine, China Medical University, Taichung 40402, Taiwan. 3Department of Fashion Design, Asia University, Taichung 41354, Taiwan.
4School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China.
5Institute of Biomedical Engineering and Materials Science, Central Taiwan University of Science
and Technology, Taichung 40601, Taiwan.
a[email protected], b[email protected]
Keywords: Fiber composite, tensile, tear, puncture resistance.
Abstract. For application as surface layer of PU composites for the future, puncture resistance and inflame retarding property are both considered. Therefore, in this preliminary study, we discussed effect of Nylon fiber fineness and hot pressing on tensile, tear and puncture resistance properties of fiber composite composed of inflame retarding nonwoven and Nylon/PET nonwoven. Result shows that, Fiber composite with finer Nylon fibers exhibited higher tensile strength and puncture resistances. Hot pressing decreased tensile strength, tear strength and puncture resistance by 5-mm needle penetration, but increased puncture resistance by 2-mm needle penetration.
Introduction
With development of industry, a large number of package materials need during transportation by train, plane, vehicle for protecting from objects damage. In process of transit transport, objects are suffered from damage from sharp weapons and then destroy themselves. Therefore, woods are usually used for packing machinery and instruments [1]. However, these materials consume a lot of non-renewable trees, which is not beneficial to sustainable development for human people. In current study, fiber composites used for packaging materials or their interlayers were prepared and then their mechanical and puncture resistance were discussed [2, 3, 4]. These composites are composed of nonwovens and/or high performance fabric. However, we would employ fiber composite as surface layer of foam composite [5] with both puncture protection and cushioning property. In this study, we aim to optimize the process parameters of surface fiber composite consisting of inflame-retarding nonwoven and supporting nonwoven. Surface nonwoven is to resist against fire hazards. The supporting nonwoven is to provide good strength. Effects of Nylon fiber fineness and hot pressing on tensile, tear and puncture resistance of fiber composite were explored.
Nylon/PET nonwoven
Nylon Denier: 3D, 15D 2mm thickness (bottom layer)
Inflame-retarding PET nonwoven
2mm thickness (surface layer)
Needle punch Experimental
Materials
3 D Nylon 6 fiber had length of 51 mm, tenacity of 4.74 g/d, elongation of 91.4 %. 15 D Nylon 6 fiber had length of 51 mm, tenacity of 4.86 g/d, elongation of 93.7 %. Both of them were provided by Ten Pow Chemical Industry Co., Ltd, Taiwan. Low melting PET fibers (LPET) provided by Far Eastern New Century Textile Ltd., Taiwan, possessed 4 D fineness, 51 mm length, 3.4 g/d tenacity and 120 ˚C melting point. Recycled high-strength PET fibers (RPET) were taken from 1000 D/192 f high-strength PET selvages provided by Hsinnjy Nonwoven Co., Ltd., Taiwan. Flame-retarding PET fiber (FPET) had 6 D fineness, 64mm length, 3.0 g/d, 32-35 limiting oxygen index (LOI) provided by Far Eastern New Century Textile Ltd., Taiwan.
Sample Preparation and Tests
60 wt% Nylon fibers, 20 wt% LPET fibers and 20 wt% RPET fibers were firstly formed into Nylon/PET nonwoven (250 g/m2) via needle-punching at 62.5 needles/cm2. Denier of Nylon fibers
was changed as 3 D and 15 D. FPET staple fibers were fabricated into FPET nonwoven (250 g/m2)
via needle-punching at 31.3 needles/cm2. After that, one layer of Nylon/PET nonwoven and one
layer of FPET nonwoven were needle-punched at density of 31.3 needles/cm2 forming
inflaming-retarding fiber composites. The fiber composite was hot-pressed through 2-mm gap Twin-Roller Hot Presser at 120 ˚C and speed of 0.5 m/min. The un-hot-pressed fiber composite was considered as the control group as shown in Figure 1. Finally, effects of hot-pressing and Nylon fineness on mechanical properties were discussed. Tensile, tear strengths and puncture resistances were conducted by Instron 5566 according to ASTM D5035, ASTM D5035, and ASTM F1342. Two probes with 2-mm diameter and 5-mm diameter respectively penetrated through samples in puncture test.
Figure 1. Structure diagram of fiber composite before hot pressing. Results and Discussion
Influence of fiber fineness and hot pressing on tensile property
Figure 2 shows comparative tensile property of fiber composites along CD (cross direction) and MD (machine direction) before and after hot pressing. CD tensile strength is higher than MD tensile strength, because of more fibers oriented along CD. It can be also found that fiber composite containing 3 D Nylon fibers has the higher tensile strength than that containing 15 D fibers. That is because when Nylon/PET nonwoven contained finer 3 D Nylon fibers, amount of fibers brought by pinhook at repeated needle-punches become higher, thereby generating higher compact fiber composite and higher tensile strength. In addition, hot pressing affects tensile strength
insignificantly due to lower-contained low-melting PET fibers, but decreases coefficient of variation of CD tensile strength for fiber composites comprising 15 D Nylon fibers.
Figure 2. Tensile strengths along CD and MD of fiber composites containing 3 D and 15 D Nylon fibers before and after hot-pressing at 120 ˚C.
Influence of fiber fineness and hot pressing on tear property
Figure 3 shows tear strengths along CD and MD of fiber composite before and after hot pressing effect. After hot-pressing, tear strengths along CD and MD decrease. This is because when Nylon/PET nonwoven was punched with inflame-retarding nonwoven, a part of low-melting fibers was taken into FPET nonwoven and dispersed between two kinds of nonwovens, conversely producing easily-fractured weakness among fibers. Comparatively, fiber composite with 15 D Nylon fibers has higher tear strength than that with 3 D Nylon fibers regardless of CD and MD, because 15 D fiber had higher tenacity than 3D fiber.
Figure 3. Tear strengths along CD and MD of fiber composites containing 3 D and 15 D Nylon fibers before and after hot-pressing at 120 ˚C.
Influence of fiber fineness and hot pressing on puncture resistance
Figure 4(a) and (b) shows puncture resistance of fiber composite after penetration by 2-mm diameter and 5-mm diameter needles. As shown in Figure 4(a), finer needle penetration produces lower puncture resistance because needle tip is finer, and nonwoven has porous structure whose pore size is 0.5 mm, hence needle easily penetrated into fiber composite. After hot pressing, 2-mm needle puncture resistance of fiber composite increases. This is due to fact that pore size becomes smaller after hot pressing, and needle not easily opens fibers among fiber composite. It is found from Figure 4(b) that hot pressing decreases puncture resistance by 5-mm diameter needle
penetration. This is because needle diameter is larger than pore size among fiber composites, and fiber composite is too compact to push aside by needle, thus coarser needle difficultly penetrates through fibers interspaces.
Combing with Figure 4(a) and (b), 3 D Nylon composite displays higher puncture resistance than 15 D Nylon. This is because puncture resistance is affected by volume density of fiber composite, and more fibers would be push aside for fiber composite containing 3 D Nylon fibers. In addition, fiber composite by 2-mm penetration needle displays lower than that by 5-mm needle. This is explained by contact area between needle and fibers, that is, coarser needle have higher contact area with fiber composite.
Figure 4. Puncture resistance penetrated by 2-mm (a) and 5-mm (b) diameter needles of fiber composites containing 3 D and 15 D Nylon before and after hot-pressing at 120 ˚C.
Conclusion
In this study, we prepared fiber composite using inflame-retarding nonwoven and Nylon/PET nonwoven. Surface inflame-retarding nonwoven had ability to retard fire spreading. Effects of Nylon fiber fineness and hot pressing on mechanical property including tensile, tear strengths and puncture resistance were discussed respectively. Fiber composite with finer Nylon fibers exhibited higher tensile strength and puncture resistances. Hot pressing decreased tensile strength, tear strength and puncture resistance by 5-mm needle penetration, but increased puncture resistance by 2-mm needle penetration. Relatively, tear strength was affected by fiber tenacity, and coarser Nylon fiber had the higher tear strength. The resultant fiber composite would be used the surface layer of foam composite for puncture protection and flame retarding.
Acknowledgement
The authors would especially like to thank National Science Council of the Taiwan, for financially supporting this research under Contract NSC 99-2622-E-035-008-cc3.
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