Thermal behaviour of binary and ternary copolymers containing acrylonitrile

Three types of acrylonitrile copolymers (acrylonitrile-styrene-butadiene copolymer (ABS¹), acrylonitrile-styrene random copolymer (SAN²) and acrylonitrile-butadiene random copolymer (BAN³) were studied by thermogravimetry (TG/DTG⁴) and by pyrolysis in a semi-batch process at 450 °C in order to find structure–thermal behaviour relationships. The overlapped thermo-oxidative degradation processes were separated and the corresponding kinetic parameters were calculated. The TG/DTG studies have evidenced that the styrene-acrylonitrile interactions stabilize the nitrile groups reacting by chain scission rather than cyclization and destabilize the styrene units. Also, the cyclization of the acrylonitrile units in ABS is favoured by interactions with the styrene and butadiene units. The pyrolysis behaviour evidenced that the styrene-acrylonitrile interactions in SAN and ABS lead to the formation of 4-phenylbutyronitrile as the most important decomposition compound. ABS shows similar composition of the degradation oil with SAN copolymer therefore in the ABS the styrene-butadiene interactions are less important than those between styrene and acrylonitrile units.     

THERMAL DECOMPOSITION AND FLAMMABILITY OF ACRYLONITRILE-BUTADIENE-STYRENE/MULTI-WALLED CARBON NANOTUBES COMPOSITES

Thermal and flammability properties of acrylonitrile-butadiene-styrene copolymer (ABS) with the addition of multi-walled carbon nanotubes (MWNTs) were studied.ABS/MWNTs composites were prepared via melt blending with the MWNTs content varied from 0.2% to 4.0% by mass.Thermogravimetry results showed that the addition of MWNTs accelerated the degradation of ABS during the whole process under air atmosphere,and both onset and maximum degradation temperature were lower than those of pure ABS.The destabilizat...     

The investigation of intumescent flame-retarded ABS using zinc borate as synergist

The influence of zinc borate (ZB) on the flammability and thermal properties of acrylonitrile–butadiene–styrene copolymer (ABS)/ammonium polyphosphate (APP)/poly(p-ethylene terephthalamide) (PETA) system was investigated. When the loadings of ABS, APP, PETA, and ZB were 70, 20.8, 6.9, and 2.3 %, respectively, the LOI value reached 36 and UL-94 vertical burning test was V-0. Even when 1.5 % ZB was added into ABS/APP/PETA (80/13.9/4.6) system, the LOI value was also 27. The thermal degradation of the composites was investigated by means of thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy (FTIR). The TG indicated that the addition of ZB improved the thermal stability and the char residue of the ABS/APP/PETA system. What’s more, the mechanism was investigated by FTIR. The spectrum of flame retardant residue suggested that ZB reacted with APP/PETA physically. Additionally, scanning electron microscopy showed that the surface of intumescent charred layer obtained after combustion of ABS/APP/PETA/ZB (70/20.8/6.9/2.3) was compact and thick.     

Thermal and photo-degradation of unstabilized ABS

Thermal- and photo-stabilities of unstabilized acrylonitrile-butadiene-styrene terpolymer, ABS, have been investigated by i.r. spectroscopy. Degradation of ABS samples is initiated by attack on the polybutadiene (PB) component; oxidation products containing hydroxyl and carbonyl groups are produced. The effect of prior thermal processing is to introduce into the polymer hydroperoxides arising from oxidative destruction of PB-unsaturation; these hydroperoxides act as catalysts during subsequent u.v. irradiation. The insolubility of degraded samples of ABS is associated with the formation of cross-linked structures and occurs mainly in the PB segment. It is concluded that the degradation characteristics of ABS are essentially those of the polybutadiene component.     

Evaluation of the thermal degradation of PC/ABS/montmorillonite nanocomposites

Polycarbonate (PC)/acrylonitrile‐butadiene‐styrene (ABS) polymer alloy/montmorillonite (MMT) nanocomposites were prepared using a direct melt intercalation technique. The pyrolytic degradation and the thermo‐oxidative degradation of the polymer alloy and the nanocomposites were studied by thermogravimetric analysis (TGA). The kinetic evaluations were performed by the model‐free kinetic analysis and the multivariate non‐linear regression. Apparent kinetic parameters for the overall degradation were calculated. The results show that PC/ABS/MMT nanocomposites have high thermal stability and low flammability. Their pyrolytic degradation and the thermo‐oxidative degradation model are different. The pyrolytic degradation reaction of the polymer is a two‐step parallel reaction model: nth‐order reaction model, and ath‐degree autocatalytic reaction with an nth‐order reaction autocatalytic reaction, whereas the thermal oxidative degradation reaction of the polymer is a two‐step following reaction model: A → B → C of nth‐order reaction model, and autocatalytic reaction model. Copyright © 2005 John Wiley & Sons, Ltd.     

Kinetics study of thermal oxidative degradation of ABS containing flame retardant components

The thermal oxidative degradation kinetics of pure acrylonitrile–butadiene–styrene (ABS) and the flame-retarded ABS materials with intumescent flame retardant (IFR) were investigated using Kissinger, Flynn–Wall–Ozawa, and Horowitz–Metzger methods. The results showed that the degradation of all samples included two stages, the activation energy at the first stage decreased by the incorporation of these flame retardant components, while increased at the second stage. The activation energy order of the flame-retarded ABS samples at stage 2 illustrates the relationship between the composition of IFRs and their flame retardancy, FR materials with appropriate acid agent/char former ratio has higher activation energy and better flame retardancy.     

Effect of the antioxidants on the stability of poly(vinyl butyral) and kinetic analysis

The effect of several kinds of antioxidants on the stability of poly(vinyl butyral) (PVB) under air atmosphere is studied by thermogravimetry–differential scanning calorimetry method and kinetic analysis. After mixed with antioxidants, the thermal oxidative stability of PVB increases significantly, because the antioxidants could inhibit the oxidation of copolymer (stage I). The thermal oxidative stability increases in the following order: PVB < PVB/1010 < PVB/B215 < PVB/1098. However, the thermal oxidative degradation rate of PVB increases markedly after 320 °C, due to the loss of chemical activity for antioxidants gradually. The thermal stability of antioxidants increases in the following order: B215 < 1010 < 1098.     

Photooxidative and pyrolytic degradation of methyl methacrylate-alkyl acrylate copolymers

Different compositions of poly(methyl methacrylate-co-methyl acrylate) (PMMAMA), poly(methyl methacrylate-co-ethyl acrylate) (PMMAEA) and poly(methyl methacrylate-co-butyl acrylate) (PMMABA) copolymers were synthesized and characterized. The photocatalytic oxidative degradation of all these copolymers were studied in presence of two different catalysts namely Degussa P-25 and combustion synthesized titania using azobis-iso-butyronitrile and benzoyl peroxide as oxidizers. Gel permeation chromatography (GPC) was used to determine the molecular weight distribution of the samples as a function of time. The GPC chromatogram indicated that the photocatalytic oxidative degradation of all these copolymers proceeds by both random and chain end scission. Continuous distribution kinetics was used to develop a model for photocatalytic oxidative degradation considering both random and specific end scission. The degradation rate coefficients were determined by fitting the experimental data with the model. The degradation rate coefficients of the copolymers decreased with increase in the percentage of alkyl acrylate in the copolymer. This indicates that the photocatalytic oxidative stability of the copolymers increased with increasing percentage of alkyl acrylate. From the degradation rate coefficients, it was observed that the photocatalytic oxidative stability follows the order PMMABA > PMMAEA > PMMAMA. The thermal degradation of the copolymers was studied by using thermogravimetric analysis (TGA). The normalized weight loss and differential fractional weight loss profiles indicated that the thermal stability of the copolymer increases with an increase in the percentage of alkyl acrylate and the thermal stability of poly(methyl methacrylate-co-alkyl acrylate)s follows the order PMMAMA > PMMAEA > PMMABA. The observed contrast in the order of photostability and thermal stability of the copolymers was attributed to different mechanisms involved for the scission of polymer chain and formation of different products in both the processes.     

Effect of dissolution-based recycling on the degradation and the mechanical properties of acrylonitrile-butadiene-styrene copolymer

A dissolution-based recycling technique for acrylonitrile-butadiene-styrene copolymer (ABS) is proposed, and the effects of repeated recycling cycles are studied measuring changes in chemical structure, melt viscosity, and tensile and impact properties. Acetone as solvent, 0.25 g/ml concentration, room temperature and 40 min for dissolution have been found to be the most reliable recycling parameters. FTIR, DSC and MFI results have shown that the dissolution-based recycling itself does not degrade the ABS. However, TGA analysis suggests that during the dissolution some stabilizers are probably eliminated, and consequently degradation takes place in the following injection moulding step. Darkening of recycled ABS is attributed to the butadiene degradation, pointed out by FTIR results. Otherwise, the chemical structure of the SAN matrix has not been modified, but its molecular weight has been reduced. The modulus of elasticity is not affected even after four recycling cycles. However, yield stress and impact strength decrease after the first recycling cycle, and remain constant in the following steps.     

Surface modification of boron nitride via poly (dopamine) coating and preparation of acrylonitrile‐butadiene‐styrene copolymer/boron nitride composites with enhanced thermal conductivity

A biology‐inspired approach was utilized to functionalize hexagonal boron nitride (h‐BN), to enhance the interfacial interactions in acrylonitrile‐butadiene‐styrene copolymer/boron nitride (ABS/BN) composites. The poly (dopamine), poly (DOPA) layer, was formed on the surface of BN platelets via spontaneously oxidative self‐polymerization of DOPA in aqueous solution. The modified BN (named as mBN) coated with poly (DOPA) was mixed with ABS resin by melting. The strong interfacial interactions via π‐π stacking plus Van der Waals, both derived from by poly (DOPA), significantly promoted not only the homogeneous dispersion of h‐BN in the matrix, but also the effective interfacial stress transfer, leading to improve the impact strength of ABS/mBN even at slight mBN loadings. A high thermal conductivity of 0.501 W/(m·K) was obtained at 20 wt% mBN content, reaching 2.63 times of the value for pure ABS (0.176 W/(m·K)). Meanwhile, the ABS/mBN composites also exhibited an excellent electrical insulation property, which can be expected to be applied in the fields of thermal management and electrical enclosure.     

Rheological and mechanical properties of ABS plastics prepared by bulk polymerization

A series of ABS plastics prepared by bulk polymerization was studied. The test samples contained almost equal amounts of PB but mostly differed in the molecular mass of a styrene-acrylonitrile copolymer. It was shown that the molecular mass of the copolymer strongly affects the rheological and mechanical properties of ABS plastics. An increase in molecular mass leads to a rise not only in the non-Newtonian viscosity of plastics but also in their yield point, storage modulus under periodic steady-state shear flow in the low-frequency plateau region, and impact strength. Quantitative correlations between these rheological and mechanical characteristics of the copolymers and their M _w values were established. As opposed to homophase polymer systems, a marked increase in the shear stress has no effect on viscosity in relation to the molecular mass of ABS plastics. In the case of melts, the influence of the M _w of the styrene-acrylonitrile copolymer on the rheological behavior of ABS plastics is apparently related to a change in the interaction of PB particles with the copolymer that controls the structural framework of the system. The relationship between the impact strength of the copolymer and its M _W may be explained by the fact that the latter parameter influences orientational effects in crazes that arise during steady-state shear flow of ABS plastics in the solid state.     

The application of transition metal molybdates (AMoO4, A = Co,Ni, Cu) as additives in acrylonitrile‐butadiene‐styrene with improved flame retardant and smoke suppression properties

In this paper, three different kinds of typical transition metal molybdates (AMoO₄, A = Co, Ni, Cu) were synthesized via a hydrothermal method. X‐ray diffraction and scanning electron microscopy (SEM) were used to characterize their structures. Then, the synthesized molybdates were incorporated into acrylonitrile‐butadiene‐styrene (ABS) matrix via a masterbatch‐based melt blending method. SEM images showed that transition metal molybdates (AMoO₄, A = Co, Ni, Cu) are homogeneously dispersed in the ABS matrix. Thermogravimetric analysis (TGA) results indicated that the introduction of these transition metal molybdates (AMoO₄, A = Co, Ni, Cu) could accelerate the degradation of ABS, especially for the CuMoO₄. The initial thermal degradation temperatures are decreased by 9–12°C for ABS/CoMoO₄ and ABS/NiMoO₄ composites. But for the ABS/CuMoO₄ composite, it is decreased by 45°C. Meanwhile, the peak of heat release rate is decreased by 10%–13% for ABS/CoMoO₄ and ABS/NiMoO₄ composites, and it is decreased by 26% for ABS/CuMoO₄ composite. Moreover, TGA/infrared spectrometry was used to investigate the smoke suppression effect of CuMoO₄ in ABS indirectly; it showed that the addition of CuMoO₄ inhibits the release of hydrocarbons, aromatic compounds, and CO and promotes the generation of CO₂. Copyright © 2014 John Wiley & Sons, Ltd.     

Photooxidation of ABS of long-wavelengths

The evolution of the photochemical degradation of ABS has been studied in conditions of long wavelength irradiation (λ's> 300 nm). The main photoproducts involved in the oxidative evolution have been identified by using FTIR spectroscopy and chemical titrations. A particular attention has been devoted to α–β unsaturated ketones that appear as secondary photoproducts. Those ketones present a low photochemical stability when exposed in the range 300–400 nm. Conditions for their formation have been experimentally studied. Formation of oxidation photoproducts has been also studied at the macroscopic level and it has been shown that their repartition in the polymer is heterogeneous. The origins of the heterogenities have been studied.     

Thermal degradation of copolymers of methyl methacrylate and methyl acrylate. II. Chain scission and the mechanism of the reaction

It has been established that one molecule of carbon dioxide is produced for each chain scission during degradation of methyl methacrylate–methyl acrylate copolymers with molar compositions in the ratios 112/1, 26/1, 7.7/1, and 2/1. Thus the relatively simple measurement of the production of carbon dioxide can be used to determine the extent of chain scission. In this way the relationships between chain scission and volatilization, zip length, copolymer composition, and the production of permanent gases have been established. The rate of chain scission is proportional to a power of the methyl acrylate content of the copolymer less than 0.5, from which it has been concluded that a significant proportion of the initial production of radicals and the subsequent attack of these radicals on the polymer chains is at random and not specifically associated with the methyl acrylate units. A mechanism for the overall thermal degradation process in this copolymer system is presented in the light of these observations.     

Toughening of nylon‐6 with epoxy‐functionalized acrylonitrile‐butadiene‐styrene copolymer

Glycidyl methacrylate (GMA) functionalized acrylonitrile‐butadiene‐styrene (ABS) copolymers have been prepared via an emulsion polymerization process. The epoxy‐functionalized ABS (e‐ABS) particles were used to toughen nylon‐6. Molau tests and FTIR results showed the reactions between nylon‐6 and e‐ABS have taken place. Scanning electron microscopy (SEM) displayed the compatibilization reaction between epoxy groups of e‐ABS and nylon‐6 chain ends (amine or carboxyl groups), which improve disperse morphology of e‐ABS in the nylon‐6 matrix. The presence of only a small amount of GMA (1 wt %) within the e‐ABS copolymer was sufficient to induce a pronounced improvement of the impact strength of nylon‐6 blends; whereas further increase of the GMA contents in e‐ABS resulted in lower impact strength because of the crosslinking reaction between nylon‐6 and e‐ABS, resulting in agglomeration of the ABS particles. SEM results showed shear yielding of the nylon‐6 matrix and cavitation of rubber particles were the major toughening mechanisms. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2170–2180, 2005     

Thermal decomposition of polymer mixtures of PVC,PET and ABS containing brominated flame retardant: Formation of chlorinated and brominated organic compounds

The thermal decomposition of various mixtures of acrylonitrile butadiene styrene copolymer (ABS), ABS containing brominated epoxy resin flame retardant and Sb₂O₃, poly(ethylene terephthalate) (PET) and poly(vinyl chloride) (PVC) has been studied in order to clarify the reactions between the components of mixed polymers. More than 40 halogen-containing molecules have been identified among the pyrolysis products of mixed samples. Brominated and chlorinated aromatic esters were detected from the mixtures containing PET and halogen-containing polymers. A series of chlorinated, brominated and mixed chlorinated and brominated phenols and bisphenol A molecules have been identified among the pyrolysis products of polymer mixtures containing flame retarded ABS and PVC. It was established that the decomposition rate curves (DTG) of the mixtures were not simple superpositions of the individual components indicating interactions between the decomposition reactions of the polymer components. The maximal rate of thermal decomposition of both ABS and PET decreases significantly if the mixture contains brominated epoxy flame retardant and Sb₂O₃ synergist. The dehydrochlorination rate of PVC is enhanced in the presence of ABS or PET.     

Catalyzing carbonization function of ferric chloride based on acrylonitrile-butadiene-styrene copolymer/organophilic montmorillonite nanocomposites

A study on the Lewis acids-type transition metal chloride (FeCl₃) catalyzing carbonization based on acrylonitrile-butadiene-styrene copolymer (ABS)/organophilic montmorillonite (OMT) nanocomposites has been achieved. The results of XRD, TEM and HREM experiments show the formation of intercalated structure. The thermal stability of the nanocomposites slightly decreases, but the char residue remarkably increases compared with pure ABS. Meanwhile, it is found that the loading of FeCl₃ leads to crosslinking of ABS, promotes the charred residue yield and catalytic graphitization effect. The structure and morphology (XRD, HREM, SAED and LSR) of the purified char residue approve further the presence of graphite sheets. The possible catalyzing carbonization mechanism is composed of three prominent aspects. The first is the catalyzing effect of FeCl₃ promoting the crosslinking of polymer. The second is the Hofmann degradation of OMT, whose degraded products have opposite role in promoting crosslinking reactions and the last is the nano-dispersed clay layers. The gas barrier properties of clay stop or reduce the release of the pyrolytic products, which have been dehydrogenated for more time and aromatized to form char.     

HCN evolution from thermal and oxidative degradation of poly(diphenyl methane pyromellitimide) at high temperatures

HCN evolution from thermal and oxidative degradation of poly(diphenyl methane pyromellitimide) has been investigated over a range of temperatures from 500 to 1000°C; rate constants and Arrhenius equations have been determined. Kinetics and mechanisms have been proposed and quantitatively evaluated. They account well for the experimental results. The rate determining steps are C? N scission for thermal degradation and H abstraction from the methylene bridge by O₂ for oxidative degradation, respectively. At high temperatures, oxidation and thermal decomposition of the evolved HCN take place on its passage through the hot zone of the furnace in the highest range of temperatures (800–1000°C). Additional HCN is produced (>800°C) from the char obtained during thermal and oxidative degradation.     

Radiolysis of alkyl benzene sulfonat (ABS) in aqueous solution

Degradation of alkyl benzene sulfonate (ABS) in aerated aqueous solution irradiated with gamma radiation with doses up to 1.8 kGy were studied. The degree of degradation, pH change, the effect of pH on the degradation, COD values and the degradation products were determined. The degradation of ABS increases with the increase of doses and decreases with the increase of ABS concentration. The degradation was somewhat more efficient in slightly acidic and neutral solutions than at basic pH oxalic acid was detected by HPLC as degradation product.     

SAN共聚物组成对PVC/ABS共混物相容性的影响

采用乳液聚合技术通过改变共聚单体的投料比(St/AN)合成了一系列不同AN结合量的ABS接枝共聚物粉料和SAN共聚物.将其与聚氯乙烯(PVC)和邻苯二甲酸二辛酯(DOP)熔融共混分别制得了PVC/ABS、PVC/SAN、PVC/ABS/DOP和PVC/SAN/DOP共混物,利用SEM、TEM和动态力学粘弹谱仪(DMA)对共混物的相容性和相结构进行了表征.结果发现,在PVC/ABS共混体系中,尽管改变接枝SAN共聚物的AN结合量,PVC和SAN共聚物均为不相容体系;在该共混物中引入增塑剂DOP后,虽然当SAN共聚物AN结合量小于23.4 wt%时,共混物在室温以上只存在一个tanδ峰,但形态结构研究结果表明共混物仍为不相容体系,共混物的相区尺寸明显地依赖于SAN共聚物中的AN结合量,当AN结合量为23.4 wt%时相区尺寸最小.