scholarly journals A Geometry Effect of Carbon Nanomaterials on Flame Retardancy and Mechanical Properties of Ethylene-Vinyl Acetate/Magnesium Hydroxide Composites

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1028 ◽  
Author(s):  
Zhi-Qi Liu ◽  
Zhi Li ◽  
Yun-Xian Yang ◽  
Yan-Ling Zhang ◽  
Xin Wen ◽  
...  

This study was aimed at investigating the effects of carbon nanomaterials with different geometries on improving the flame retardancy of magnesium hydroxide–filled ethylene-vinyl acetate (EM). The thermal stability and flame retardancy were studied by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 test, and cone calorimeter test (CCT). The in situ temperature monitoring system and interrupted combustion offered direct evidence to link flame retardancy and composite structure. Results demonstrated that carbon nanomaterials enhanced the thermal stability and fire safety of EM. The geometry of carbon nanomaterials played a key role in synergistic flame retardancy of EM, with the flame-retardant order of carbon nanotube > nanoscale carbon black > graphene. Based on an online temperature monitoring system and interrupted combustion test, one-dimensional carbon nanotube was more inclined to form the network structure synergistically with magnesium hydroxide in ethylene-vinyl acetate, which facilitated the generation of more continuous char structure during combustion. In parallel, the mechanical property was characterized by a tensile test and dynamic mechanical analysis (DMA). The incorporation of carbon nanomaterials presented a limited effect on the mechanical properties of the EM system.

10.6036/10031 ◽  
2021 ◽  
Vol 96 (3) ◽  
pp. 302-308
Author(s):  
XIAN WANG ◽  
JUNYI DAI ◽  
TIANQING XING ◽  
JINLONG ZHUO

Ethylene-vinyl acetate copolymer (EVA) is widely used due to its good processability, low density, and low temperature resistance. However, it burns easily and has several disadvantages, such as a high heat release rate and melt dripping, and it emits large amounts of smog and toxic harmful gases. These disadvantages greatly limit the application of EVA in the wire and cable field. In this study, a series of carbon fiber (CF)/9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)/EVA composites are prepared through melt compounding to improve the flame retardancy and mechanical properties of EVA. The flame retardancy, thermal stability, and mechanical properties of the composites are studied through microscale combustion calorimeter experiments, cone calorimeter tests, thermogravimetric analysis, digital camera, and tensile measurements. Results indicate that among the six samples, the EVA-5 composite with 4.0 wt% CF, 16.0 wt% DOPO, and 80 wt% EVA has the highest limiting oxygen index value (25.1%) and reaches the V-1 level of the Underwriters Laboratory-94 test. Compare with that of pure EVA, the peak heat release rate of the EVA-5 composite has reduced by 30.2% and 47.7%. In addition, the total heat release of EVA-5 reduces by 17.0% and 34.8% relative to that of pure EVA. Data of thermogravimetric analysis show that the thermal stability of CF/DOPO/EVA improves with the increase in CF loading. Moreover, the tensile strength and elongation-at-break values of EVA-5 are 14.30 MPa and 1142.87%, respectively, indicating that this material can maintain good mechanical properties. CF not only enhances the tensile properties of EVA but also acts as a skeleton during burning. This action could increase the strength of the carbon layer and enhance the flame-retardant effect of DOPO. CF and DOPO have an enhanced synergistic effect that could improve the flame retardancy, thermal stability, and mechanical properties of EVA composites. This work provides a theoretical basis for the preparation and production of CF/DOPO/EVA composites with good comprehensive performance. Keywords: thylene-vinyl acetate copolymer; 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; carbon fiber; flame retardant; synergistic effects


Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2107
Author(s):  
Dongwei Yao ◽  
Guangzhong Yin ◽  
Qingqing Bi ◽  
Xu Yin ◽  
Na Wang ◽  
...  

In this study, we selected basalt fiber (BF) as a functional filler to improve the mechanical properties of ethylene vinyl acetate (EVA)-based flame retardant materials. Firstly, BF was modified by grafting γ-aminopropyl triethoxysilane (KH550). Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) were used to comprehensively prove the successful modification of the BF surface. Subsequently, the modified BF was introduced into the EVA/magnesium hydroxide (MH) composites by melt blending. The limiting oxygen index (LOI), UL-94, cone calorimeter test, tensile test, and non-notched impact test were utilized to characterize both the flame retardant properties and mechanical properties of the EVA/MH composites. It was found that the mechanical properties were significantly enhanced without reducing the flame retardant properties of the EVA/MH composites. Notably, the surface treatment with silane is a simple and low-cost method for BF surface modification and the pathway designed in this study can be both practical and effective for polymer performance enhancement.


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