Abstract:A poliaramida (aramida) é um polímero de alto desempenho, cujas principais características são a elevada tenacidade, baixo alongamento e resistência ao calor. Devido ao desconhecimento do mercado em geral a respeito de materiais têxteis, metodologia de ensaios e a nomenclatura utilizada nesta família de materiais, invariavelmente ocorrem erros na escolha da qualidade do produto a adquirir. O uso de equipamentos inadequados para caracterização deste material pode levar a erros de interpretação. Este trabalho vi… Show more
“…For ARA-100, it is possible that the lack of alignment of aramid fibers as a result of the weaving process has caused partial break of the fibers, hindering their ballistic performance for this type of ammunition. 40–47 Moreover, ballistic impacts from 9 mm handguns apply deformation rates close to 10 4 s −1 , 2 similar to those observed at the SHPB, and similar to the ballistic tests presented in Table 4, thus corroborating the V 50 results herein found.…”
Section: Resultssupporting
confidence: 85%
“…In addition to that, the partial break of the fibers in the weaving process may have also played a role in the reduced storage modulus of this composite. 35,40,50 Figure 4.Storage modulus (a), loss modulus (b), and tan delta (c) of the composites.…”
The development of impact resistant hybrid composites for ballistic applications is a recent trend. The increased energy absorption and reduced weight are some of the advantages for using these composites. Hybrid composites constituted of ultra-high molecular weight polyethylene (UHMWPE) laminates and aramid fiber fabrics were obtained by autoclave molding. The dynamic compression test was performed using a Split Hopkinson pressure bar with a standard deformation rate. The V50 ballistic limit test was carried out following the military standard MIL-STD-662F. The ballistic table NIJ Standard 0108.01 was taken as a reference and 9 mm Luger FMJ and .44 Mag Lead SWC EXPP ammunition were used. The dynamic-mechanical properties of the hybrid composites were evaluated. The composites exhibited an areal density of 5.30 ± 0.05 kg.m−2, meeting the required criteria in NIJ 0108.01. The V50, maximum stress, tenacity, storage modulus and tan delta peak height depended on the proportion of UHMWPE used in the hybrid composites: the best results were obtained for the composites with 75% UHMWPE and 25% aramid.
“…For ARA-100, it is possible that the lack of alignment of aramid fibers as a result of the weaving process has caused partial break of the fibers, hindering their ballistic performance for this type of ammunition. 40–47 Moreover, ballistic impacts from 9 mm handguns apply deformation rates close to 10 4 s −1 , 2 similar to those observed at the SHPB, and similar to the ballistic tests presented in Table 4, thus corroborating the V 50 results herein found.…”
Section: Resultssupporting
confidence: 85%
“…In addition to that, the partial break of the fibers in the weaving process may have also played a role in the reduced storage modulus of this composite. 35,40,50 Figure 4.Storage modulus (a), loss modulus (b), and tan delta (c) of the composites.…”
The development of impact resistant hybrid composites for ballistic applications is a recent trend. The increased energy absorption and reduced weight are some of the advantages for using these composites. Hybrid composites constituted of ultra-high molecular weight polyethylene (UHMWPE) laminates and aramid fiber fabrics were obtained by autoclave molding. The dynamic compression test was performed using a Split Hopkinson pressure bar with a standard deformation rate. The V50 ballistic limit test was carried out following the military standard MIL-STD-662F. The ballistic table NIJ Standard 0108.01 was taken as a reference and 9 mm Luger FMJ and .44 Mag Lead SWC EXPP ammunition were used. The dynamic-mechanical properties of the hybrid composites were evaluated. The composites exhibited an areal density of 5.30 ± 0.05 kg.m−2, meeting the required criteria in NIJ 0108.01. The V50, maximum stress, tenacity, storage modulus and tan delta peak height depended on the proportion of UHMWPE used in the hybrid composites: the best results were obtained for the composites with 75% UHMWPE and 25% aramid.
“…These properties are particularly manifested when all of the aromatic groups are linked in the para position [3] . Commercial aramids, mostly in the form of fibers, are used as reinforcement for thermal and ballistic protection [4] .…”
Aromatic polyamides have properties of industrial relevance. However, the industrial and technological advancement has followed the trend of sustainability by seeking renewable source materials. In this work, polyamides were synthetized using 2,5-furandicarboxylic acid with p-phenylene diamine, triphenyl phosphite and two solvents (NMP and DMAc). To evaluate the influence of solvents on the reaction, a kinetic study of degradation was carried out by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and viscometric analysis. The viscosity value was in the range 70-80 mL/g. The TGA showed a higher thermal stability and activation energy for sample prepared with DMAc than the NMP. The XRD analysis showed that the PAF DMAc presents more defined crystalline forms due to its higher solvation capability. The crystalline form can be correlated with the differences of Ea, because the crystalline orientation and the number of hydrogens bonds in sample PAF NMP may be lower than the structure attributed to PAF DMAc .
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