Synthesis and Thermal Properties of Acrylonitrile/Butyl Acrylate/Fumaronitrile and Acrylonitrile/Ethyl Hexyl Acrylate/Fumaronitrile Terpolymers as a Potential Precursor for Carbon Fiber (original) (raw)
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Fibers
The aim of this work is to review a possible correlation of composition, thermal processing, and recent alternative stabilization technologies to the mechanical properties. The chemical microstructure of polyacrylonitrile (PAN) is discussed in detail to understand the influence in thermomechanical properties during stabilization by observing transformation from thermoplastic to ladder polymer. In addition, relevant literature data are used to understand the comonomer composition effect on mechanical properties. Technologies of direct fiber heating by irradiation have been recently involved and hold promise to enhance performance, reduce processing time and energy consumption. Carbon fiber manufacturing can provide benefits by using higher comonomer ratios, similar to textile grade or melt-spun PAN, in order to cut costs derived from an acrylonitrile precursor, without suffering in regard to mechanical properties. Energy intensive processes of stabilization and carbonization remain a...
“Examination of the Chemical Mechanisms During Thermal Treatment of Carbon Fiber Pan Precursors”
2015
Although not fully understood, the prevailing literature opinion is, that radical processes make a major contribution during thermal stabilization of carbon fiber PAN (polyacrylonitrile) precursors and are even the only mechanisms to occur in homopolymers under inert conditions, forming a continuous ladder structure. However, the facts, that a) the origin of these radicals remains unknown and b) the radicals introduced during the PAN synthesis do not induce any cyclization reactions, casted some doubt on this mechanism in our view. Therefore various thermal and spectroscopic experiments on PAN homopolymers with differently deuterated sites and novelly synthesized corresponding oligomers, containing several Acrylonitrile repeating units, have been conducted in this present work, to further evaluate the ongoing mechanisms during the thermal stabilization processes. Besides that, chemical agents were added to polymer and oligomer samples and their influences on the thermal behaviour ha...
International Journal of Chemical Engineering and Applications, 2012
Redox polymerization of acrylonitrile (AN) with methyl acrylate and fumaronitrile as comonomer and termonomer respectively, were carried out by using sodium bisulfite (SBS) and potassium persulphate (KPS) as initiator at 40°C. The effect of methyl acrylate (MA) and fumaronitrile (FN) on the glass transition temperature (T g) and stabilization temperature has been studied by Differential Scanning Calorimetry (DSC). The degradation behavior and char yield were obtained by Thermogravimetric Analysis. The T g of poly(AN/MA) copolymers were found to be lower (~70°C) as compared to polyacrylonitrile (PAN) (210°C). However, by incorporating MA into PAN system, the char yield reduced significantly.It was found that FN reduced the initial cyclization temperature of poly(AN/MA/FN) terpolymer to ~230°C as compared to poly(AN/MA) copolymer (~260°C). In addition, FN reduced the heat liberation per unit time during the stabilization process that consequently reduced the emission of volatile group during this process. Thereby, the char yield of poly(AN/MA/FN) 90/4/6 terpolymer is higher at 51% as compared to poly(AN/MA) 90/10 copolymer (45%).
Progress in Materials Science, 2020
PolyAcriloNitrile (PAN) is a versatile man-made polymer and has been used in a large array of products since its first mass production in mid 40's. Among all applications of PAN the widely used application is in manufacture of precursor fibre for fabrication of carbon fibres. The process of PAN-based carbon fiber production comprises fibre spinning, thermal stabilization and carbonization stages. Carbon fiber properties are significantly dependent on the quality of PAN precursor fibre and in particular the process parameters involved in thermal stabilisation. This paper is the first comprehensive review that provides a general understanding of the links between PAN fiber structure, properties, and its stabilization process along with the use of mathematical modelling as a powerful tool in prediction and optimisation of the processes involved. Since the promise of the mathematical modelling is to predict the future behaviour of the system and the value of the variables for the unseen or unmeasured domain of variables, this review will be valuable in further understanding of the intricate processes of carbon fibre manufacture and utilising the advanced mathematical modelling techniques to predict and optimize a range of critical factors that control the quality of PAN and resultant carbon fibers.
NanoWorld Journal, 2015
The aim of this work is the presentation of two different approximations for improving the production of carbon fibers through the introduction of alternative precursors. The first approach concerns the development of novel polyacrylonitrile block copolymers through activators' generated by electron transfer-atom transfer radical polymerization (AGET-ATRP) reaction mechanism in microemulsion; the novel polymers are envisaged to contain a structure that will be more efficiently oxidatively stabilized and/or carbonized, with the ultimate target of CFs with improved properties. The second approximation aims at the introduction of lignin as efficient CFs precursor; this approach aims at reducing the cost of the process and increasing the production yield. Pyrolysis together with oxidative stabilization of lignin were investigated, as well as the effects on structure and thermal behavior of blending with thermoplastics. Thus far, both these methodologies exhibited significant potential and will be further developed towards full scale industrial application.
Polyacrylonitrile (PAN) fiber is the best precursor for carbon fibers due to high carbon content after heat treatment. After the polymer was spun into fibers, the fibers will undergo pretreatment process with chemical solution known as post spinning treatment. Post spinning will directly affect conversion of PAN fiber to carbon fiber. Oleic acid was used as post spinning treatment chemical solution to PAN fibers. The pretreated PAN fiber will be heated at 250 o C and 800 o C. The fibers were studied using Fourier Transform Infra-Red (FTIR), X-ray Photoelectron Spectroscopy (XPS) and DSC to study the chemical change during heat treatment. PAN fibers treated with oleic acid have reduced the cyclization energy and increase oxygen and carbon content leading to high performance carbon fibers. 1 Introduction. Carbon fiber was used in high performance composite due to excellence weigh to strength ratio. Carbon fiber reinforced composite became more important in aerospace, civil engineering, military, and motorsports, along with other competition sports [1-2]. Carbon fibers can be derived from pitch based, polyacrylonitrile (PAN) polymer or rayon based chemicals. However most high performance carbon fiber was converted from polyacrylonitrile (PAN) based polymer due to high carbon content after heat treatment process [3]. Polyacrylonitrile (PAN) polymer was spun to form polyacrylonitrile (PAN) fiber and treated with solution known as post spinning treatment. Post spinning were divided into three categories, such as modification through coating, impregnation with chemicals (catalytic modification) and drawing/stretching with plasticizer [4,5,6 ]. Previous study shows fatty acid derivatives react as coating agent to reduce the entangling, fluffy, fusion and fiber to fiber adhesion of the PAN precursor fibers during thermal stabilization process [7]. In this paper an attempt to prove that fatty acid without any derivative can give similar effect to fatty acid derivatives coating type post spinning modification process. The post spinning modifications indirectly affect and ease the stabilization in several ways such as reducing the activation energy of cyclization, decreasing the stabilization exotherm, increasing the speed of cyclization reaction and also improving the orientation of molecular chains in the fibers [8]. Recently, the stabilization process is found to play an important role in converting PAN fiber to an infusible stable ladder polymer that converts C=N bonds to C≡N
2012
Polyacrylonitrile (PAN)/acrylamide (AM) fibers were fabricated via dry-jet wet spinning process using a solvent-free coagulation bath. The effects of AM loading as comonomer on the mechanical and thermal properties of PAN-based carbon fiber have been studied. The thermal stability and mechanical stability of the fibers were characterized using differential scanning calorimetry (DSC) and tensile testing. Fibers fabricated from PAN with 5 wt% AM had the highest Young Modulus at 5.54 GPa. It also showed better exothermic trend process with broader exothermic peak and lower initiation stabilization temperature compared with homopolymer PAN. The elemental composition and chemical structure evolution of the fibers during the heat treatment processes were evaluated by elemental analyzer and Fourier Transform Infrared Spectroscopy. Crystal structure evolution of the fibers during the heat treatment process was elucidated by X-ray diffraction (XRD) analysis. The elemental analyzer, XRD and FTIR results revealed that pyrolysis process used had successfully transformed PAN/AM fibers produced from solvent free coagulation bath into carbon fibers that were comparable with the conventional coagulation bath.
Thermal behavior of carbon fiber precursor polymers with different stereoregularities
Journal of Thermal Analysis and Calorimetry, 2012
The effect of stereoregularity, in terms of isotactic triad content on the thermal behavior of carbon fiber precursor polymers synthesized through different polymerization routes such as solid state and radical solution polymerization techniques, was investigated by the thermo gravimetric analysis and differential scanning calorimetric measurements. The isotactic contents of I-PAN and A-PAN were estimated with 13 C NMR. The thermal cyclization reactions of atactic polyacrylonitrile (A-PAN) with low isotactic content (26.4-29.7 %) occurred at a lower temperature than that of isotactic polyacrylonitrile (I-PAN) with higher content (48.7-51.6 %). The percentage of mass loss observed in I-PAN was less as compared to A-PAN. The molecular mass characteristics of PAN obtained through solid state and radical solution polymerization were [M n (10.2-14.3 9 10 4), M v (2.44-3.26 9 10 5)] and [M n (10.2-14.3 9 10 4), M v (2.29-2.74 9 10 5)] Daltons (Da).
Synthetic Metals, 2000
Ž. Ž. Intercalation of fluorine in polyacrylonitrile PAN-based carbon fibers HTT ; 14008C was carried out in the presence of hydrogen fluoride as an additive. The study revealed that there is no definite stage formation in the fluorinated compounds, rather fluorine is trapped in the defects or diffused in to graphene layers and form covalent C-F bond at the surface of the fibers. Mechanical properties Ž. improve for lower concentrations of fluorine into the fibers up FrC ; 0.04% .