12)The rank correlation coefficient is obtained by the formula (R) is
equal to
a) 1 - 600
b) 1 + open c) both a and b d) none of these
-n
Answers
Explanation:
In the present work, statistical analysis (16 processing conditions and 2 virgin unmodified samples) is performed to study the influence of antioxidants (AOs) during acrylonitrile-butadiene-styrene terpolymer (ABS) melt-blending (220 °C) on the degradation of the polybutadiene (PB) rich phase, the oxidation onset temperature (OOT), the oxidation peak temperature (OP), and the yellowing index (YI). Predictive equations are constructed, with a focus on three commercial AOs (two primary: Irganox 1076 and 245; and one secondary: Irgafos 168) and two commercial ABS types (mass- and emulsion-polymerized). Fourier transform infrared spectroscopy (FTIR) results indicate that the nitrile absorption peak at 2237 cm−1 is recommended as reference peak to identify chemical changes in the PB content. The melt processing of unmodified ABSs promotes a reduction in OOT and OP, and promotes an increase in the YI. ABS obtained by mass polymerization shows a higher thermal-oxidative stability. The addition of a primary AO increases the thermal-oxidative stability, whereas the secondary AO only increases OP. The addition of the two primary AOs has a synergetic effect resulting in higher OOT and OP values. Statistical analysis shows that Odata are influenced by all three AO types, but 0.2 m% of Irganox 1076 displays high potential in an industrial context.
Keywords: ABS, statistical analysis, FTIR, melt processing, thermal-oxidative stability
1. Introduction
Electrical and electronic equipment (EEE) is extensively used worldwide and the production of these devices is increasing annually [1]. This results in a gradual increase in EEE waste (WEEE) generated after the end of life of these devices [1,2]. In 2016, 44.7 million metric tons of WEEE were produced worldwide and by 2021, it is expected that 52.2 million metric tons of WEEE will be created [1]. Manufacturing sustainable EEE is necessary, since the natural resources that are used to produce such devices are limited. Concerned about the increasing amount of WEEE, the European Parliament and the Council of the European Union [3] adopted the Directive 2012/19/EU, which establishes “measures to protect the environment and human health by preventing or reducing the adverse impacts of the generation and management of waste from EEE.” One of the required actions stated in this directive is associated with the recycling of WEEE, in which at least 55% of WEEE must be prepared for re-use and recycling starting in 2018.
Based on life-cycle assessment studies, the benefits of plastics recycling for the environment are evident. The recycling of plastics from WEEE results in environmental impacts about 4 times lower than those from the disposal in municipal solid waste incineration plants, and up to 10 times lower than those found in the production of virgin plastics [4]. Moreover, when considering all plastics (not only from WEEE), the use of virgin plastics instead of the recycled ones can increase the environmental impact by almost 4 times [5].
Among the plastics found in WEEE, styrene-based plastics such as high-impact polystyrene (HIPS) and acrylonitrile-