| Summary: | 博士 === 逢甲大學 === 纖維與複合材料學系 === 106 === This study aims to prepare polymer laminated composites using fiber-reinforced polymer sheets. The textile can convey the load to attain mechanical reinforcement and the polymer also provides the composites with more functionalities. The combination enables the polymer laminated composites to be more commonly used. However, the delamination between polymer covers and textile core may ruin all the required functions of the composites, and the improvement on the delamination is the priority that people are concerned about. Therefore, this study proposes a measure to strengthen polymer covers to adhere to the textile. The textiles are composed of low melting point polyester(LMPET) fibers. The polymer sheets and a textile core can be firmly bonded using the sheet extrusion process. The mechanical properties, thermal behaviors and combustion resistance of the composites are evaluated in order to examine the influences of different low LMPET fibers and different compound manners.
There are four parts of this dissertation. The first part involves the preparation of the composites which are composed of PP/Kevlar nonwoven fabrics as the core and PP or TPU sheets as the covers. The mechanical properties, thermal behavior, and combustion resistance of the PP-PP/Kevlar and TPU-PP/Kevlar composites are evaluated. The employment of sheet extrusion melts the PP fibers of the PP/Kevlar nonwoven fabrics, which bonds the PP or TPU sheets. The test results show that using PP/Kevlar nonwoven fabrics have a positive influence on the diverse properties of PP-PP/Kevlar and TPU-PP/Kevlar composites. Moreover, the peel strength test results also suggest that using PP staple fibers improves the interfacial compatibility between the covers and the core. Similarly, the combustion and DSC measurement results prove that both of the PP-PP/Kevlar and TPU-PP/Kevlar composites have a stabilized structure.
The second part involves the preparation of the composites which are composed of LMPET/Kevlar nonwoven fabrics as the core and PP or TPU sheets as the covers using the sheet extrusion machine. The manufacturing is simple and efficient. The morphology, mechanical properties, combustion resistance, and thermal behaviors of the PP-LMPET/Kevlar and TPU-LMPET/Kevlar composites are evaluated. The test results confirm that using LMPET/Kevlar nonwoven fabrics as the core effectively improves the properties of the resulting composites where Kevlar fibers featuring flame resistance and high strength and LMPET fibers strengthens the bonding among interfaces.
The third part involves using two TPUs with different viscosity. The TPUs are first blended, after which the mixture is infused at high heat to combine with Kevlar woven fabrics or LMPET/Kevlar nonwoven fabrics during the sheet extrusion process, forming TPU1/2-Kevlar and TPU1/2-LMPET/Kevlar composites. The effect of various TPU content and various Kevlar types on the mechanical properties, thermal behavior, and morphology of Kevlar-reinforced composites, which the TPU has two different viscosities and the Kevlar types are short fibers and woven fabric. The test results show that when a small amount of TPU2 that has a relatively lower viscosity is used, the composites have a more stabilized structure. In addition, the mixture and LMPET/Kevlar are effectively bonded, dispersing the externally applied loads and securing a lightweight and compact morphology. As a result, the delamination of the composites is remarkably addressed.
The fourth part involves using LMPET nonwoven fabrics as a bonding layer, which is then needle punched with the Kevlar woven fabrics or LMPET/Kevlar nonwoven fabrics, and finally bonded with TPU sheets, forming TPU-LMPET-Kevlar and TPU-LMPET-LMPET/Kevlar composites. The morphology, mechanical properties, and thermal behaviors of the two composites are studied. As far as TPU-LMPET-Kevlar composites are regarded, increasing the needle punching depth improves the tensile properties and static puncture resistance based on different damage and failure mechanisms. The results are primarily ascribed to the reinforcement caused by entangled fibers. Moreover, the peel strength increases as a result of the needle punching rate, and the thermal bonding points of LMPET fibers among layers are the major factor. As far as TPU-LMPET-LMPET/Kevlar composites are concerned, increasing needle punching rate and depth contributes to the entanglement of fibers, which stabilizes the structure and improves the tensile strength. The peel strength test results show that the melted LMPET fibers effectively bond materials at two phases, and using TPU sheets and Kevlar woven fabrics also provide the composites with good puncture resistance. Conversely, a combination of a needle punching rate being over 300 needles/min and a needle punching depth being higher than 15 mm adversely affects the structure and the enthalpy. Finally, the combustion resistance test results indicate that the pores among fibers of the core successfully protect the TPU sheets from being alight, and thus decrease the combustion rate of the composites.
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