ISSN 1678-5169 (Online) http://dx.doi.org/10.1590/0104-1428.2412 O FT-IR methodology (transmission and UATR) to quantify R automotive systems I 1 2 1,2 G Ana Carolina Ferreira , Milton Faria Diniz and Elizabeth da Costa Mattos * 1Departamento de Química, Instituto Tecnológico de Aeronáutica – ITA, São José dos Campos, SP, Brazil I 2Divisão de Química – AQI, Instituto de Aeronáutica e Espaço – IAE, São José dos Campos, SP, Brazil N *[email protected] Abstract A When using Fourier transform infrared spectroscopy (FT-IR) under the qualitative aspect for characterization of polymer blends, often a simple identification of each one of the existing polymers in the blend does not justify the material L failure since different amounts of each component may result in different mechanical properties, which should be a possible cause for of material failure when applied to an automotive part. Thus, seeking for a better justification in the understanding of material failure analysis, a new quantitative FT-IR methodology was developed in the mid-infrared region (MIR), using the transmission techniques and universal attenuated reflectance for the determination of Acrylonitrile Butadiene Styrene (ABS) and polycarbonate (PC). Transmission mode was more suitable. The relative band (A /A ) A 831 2237 was chosen for the preparation of the calibration curve that showed a 0.99% error methodology, which is within the R FT-IR spectrometer accuracy limit (≤ 2%); therefore, it is accurate for the analysis of the system. Keywords: automotive systems, MIR, polymer blends, quantification, transmission. T I 1. Introduction As known, the polymers exhibit thermal stability, the bumpers, the upholstery, the carpets, the head and tail resistance to chemical action, mechanical properties, among lamps, as well as in the door trim panels and in the roof. C others, and are currently one of the most used materials, Probably, in the future, polymers will be used in other places as external and internal components, in the automotive of such automotive systems[3]. L industry. Plastics have high reliability index and many In the automotive industry, some polymers are “enriched” advantages over traditional materials such as steel, aluminum by incorporation of loads and changes in mechanical and and glass. About 100 kg of plastics are used inside and/or thermal properties by the “healing” process, making them E [1] outside the vehicle . engineering plastics[4]. In the European automotive industry, the plastics or Engineering plastics are stable materials for certain periods. thermoplastics materials contribute to 10% of the total weight Therefore, they are used in applications where they can suffer of the vehicle, and about 41% of this material are made mechanical, thermal, electrical, chemical or environmental up of polypropylene (PP), 20% polyamide or nylon (PA), stress. In general, these are more expensive than plastic 14% ABS, 6% PC, 6% polyacetal (POM), 5% poly (butylene “commodities”, due to a more elaborate manufacturing. terephthalate) (PBT), 2% poly (methyl methacrylate) (PMMA), They are preferably chosen for their easy processability and and other materials. In the American vehicle industry, 38% of flexibility in providing more complex designs with good plastic materials are inside the car, 29% in the body, 10% in dimensional stability and excellent resistance to chemical the hood and 23% in the powertrain system and chassis. corrosion in hostile environments. The most commonly used The choice of polymer materials is at 47% PVC, 20% PP, polymers are: high molar mass polyethylene (UHMWPE), 5% polyurethane, and other materials; the non-plastic ones poly (methylene oxide) (POM), poly (ethylene terephthalate) correspond to 28%[2]. (PET), PBT, PC, PA, and others[4]. The advantages obtained from the use of plastics are related to the economy of fuel and production investments. The increasing use of polymeric materials by industries, Furthermore, the possibility of design sophistication, the use aiming to replace several traditional materials, has attracted of ways of less traditional solutions and increased safety the attention of researchers in the discovery of new materials drive the application of polymeric materials in automotive achieved through blends or polymer blends, in order to solutions. The disadvantages are: flammability, low impact obtain better performance of the mechanical properties, resistance, deterioration by thermal and environmental lower cost/benefit and environmental impact. An alternative action, etc. However, in accordance with the required that meets these requirements is the preparation of blends, specification of the material to be used, there may be a type consisting of compatibilization of polymers with different of polymer specially produced to meet the requirements of characteristics. The major advantages of these materials are use, overcoming a disadvantage found in a common plastic[1]. the range and versatility of their applications coupled with There are several types of polymers applied to the the ease of processing, enabling the production of diverse component parts of vehicles, such as the instrument panel, devices and making them incomparable with other materials[5]. 6 6/14 Polímeros, 28(1), 6-14, 2018 FT-IR methodology (transmission and UATR) to quantify automotive systems One of the most important is the blend PC/ABS. The impact resistance of PC/ABS is one of its main This importance is due not only to the acquired characteristics, properties, and the type used ABS and PC content exerts a such as impact resistance and temperature, but also to good strong influence on this property[8]. dimensional stability. It is widely used in the automotive Blends produced with high value materials, such as industry as items of the panel, steering columns covers, ABS and PC, allow to obtain products with a wide range [5] chrome logos, internal housings etc. of physical, chemical and mechanical properties. Thus ABS The virgin ABS, with an amorphous thermoplastic origin, contributes to a better processability and lower cost of the is composed of acrylonitrile (AN) (20 to 30%), styrene blend basically due to its cost per kilogram being less than (20 to 60%), the elastomeric phase consists of butadiene the cost of PC. However, PC provides good mechanical (20 to 30%). As described by Carvalho[6], it consists of and thermal properties to the blend, which justifies its use. two phases in which the SAN copolymer, composed of These two materials have a strong chemical interaction, acrylonitrile and styrene, is the continuous phase (matrix), and are dependent on the percentage of the mixture of each wherein the dispersed elastomeric phase is butadiene. component[7]. The butadiene rubber phase has grafted SAN (grafting) on With the development of various polymers, there is its surface, which ensures compatibility between the two also the need for the advancement of instrumental analysis phases. The acrylonitrile provides thermal and chemical techniques in order to determine the chemical structure of resistance, fatigue resistance, strength and stiffness; styrene new materials and/or quantify them. As known, the FT-IR provides ease of processing, gloss, hardness and rigidity; spectroscopy is one of the techniques that has merit for and butadiene provides ductility at low temperature, impact this purpose and has been successfully applied to various resistance, thermal stability and good surface finish. polymer systems in the group’s laboratories of the Divisão The PC, a thermoplastic of amorphous origin, consists of de Química (AQI) of the Instituto de Aeronáutica e Espaço long linear chains of polyesters of carbonic acid and phenols (IAE), including the use of last-edge techniques with surface (phenyl) such as bisphenol A. The presence of phenyl group analysis (universal attenuated total reflectance - UATR) in the molecular chain and two methyl groups contributes in wide spectral range (mid-infrared, MIR, near-infrared, to the rigidity of molecular PC. This rigidity has a large NIR, and others)[9-11]. effect on the properties of PC, which contributes to the lack The opportunity to develop a methodology applied to of mobility of the individual molecules, thus resulting in a polymer blends, used in the automotive sector, is still not good heat resistance and excellent impact resistance. For very explored; therefore, in the literature, FT-IR studies blends of PC/ABS, it is expected that the impact resistance [7] could be found for other types of materials for this sector, is higher than that of the matrix component . but not for the proposition of the present research. Typically the blend PC/ABS for vehicle applications Ruschel et al. reported it was possible to confirm the has about 60 to 70% PC, since it is from this content that it usefulness of this conventional technique, in combination is possible to perceive the earned properties in the blend. with the chemometric tools HCA and PCA for diesel and Due to economic and technical reasons, the blend used is biodiesel oil blends classification differentiating them from the one that has intermediate cost and properties. There are their infrared spectra even though these mixtures are composed specific applications where the properties of the PC/ABS of various types of biodiesel from three different raw materials blends are enough to achieve the necessary features for a soybean oil, residual oil and hydrogenated vegetable fat for specific piece. frying and two alcoholic routes: methyl and ethyl[12].