异山梨醇型聚碳酸酯与ABS树脂共混体系的结构与性能研究

采用异山梨醇型聚碳酸酯(DB),与掺混型ABS熔融共混制备了具有不同聚丁二烯(PB)含量和丙烯腈(AN)含量的DB/掺混型ABS合金,并在考察掺混型ABS特征对合金结构与性能的影响的基础上,分别使用同种掺混型ABS以及各种商品化ABS树脂,比较了DB/ABS合金和双酚A型聚碳酸酯/ABS合金的性能及其变化规律.结果表明,对DB/掺混型ABS(70/30)合金而言,PB含量变化对于合金拉伸性能的影响明显大于AN含量变化所带来的影响,在PB含量为6.3 wt%条件下,各不同AN含量的合金体系均有最好的性能表现.PB含量和AN含量变化对合金分散相形态的影响与力学拉伸性能变化特征一致.DB/ABS合金体系均具有良好的热稳定性与热力学相容性,受AN含量和PB含量变化的影响较小,合金玻璃化转变温度与DB非常接近.以双酚A型聚碳酸酯为基础的聚碳酸酯(PC)/ABS合金及以异山梨醇型聚碳酸酯为基础的DB/ABS合金,在拉伸性能变化上均表现出完全相同的规律,且无论是采用掺混型ABS还是采用商品化ABS的体系,PC/ABS与DB/ABS合金在拉伸性能所反映出的规律也是基本一致的.     

Microphase separation in poly(acrylonitrile–butadiene–styrene) (ABS) studied with paramagnetic spin probes. II. Simulation of electron spin resonance spectra

We recently presented electron spin resonance spectra of poly(acrylonitrile–butadiene–styrene) (ABS) doped with 10‐doxylnonadecane (10DND) and 5‐doxyldecane (5DD) as spin probes. The spectra were measured in three types of ABS that differed in their butadiene contents and methods of preparation. Results for the ABS polymers were evaluated by comparison with similar studies on the homopolymers polybutadiene (PB) and polystyrene (PS) and the copolymers poly(styrene‐co‐acrylonitrile) (SAN) and poly(styrene‐co‐butadiene) (SB). Only one spectral component was detected for 10DND in PB, PS, SAN, and SB. In contrast, two spectral components differing in their dynamic properties were detected in the ABS samples and were assigned to spin probes located in butadiene‐rich domains (the fast component) and SAN‐rich domains (the slow component). The presence of two spectral components was taken as an indication of microphase separation. In this study, we present details on the dynamics and microphase separation by simulating spectra of 10DND in ABS, PB, PS, and SAN. The simulations are based on a dynamic model defined by the components of the rotational diffusion tensor and the diffusion tilt angle between the symmetry axis of the rotational diffusion tensor and the direction of the nitrogen 2p_z atomic orbital. The jump diffusion model led to good agreement with experimental spectra. In this model, the spin probe has a fixed orientation for a given time and then jumps instantaneously to a new orientation. The temperature variation of the rotational correlation time in PB and PS consisted of two dynamic regimes, with different activation energies. The transition temperature at which the change in dynamics occurs (T_tr) is 380 K for PS and 205 K for PB, essentially the same as the corresponding glass‐transition temperatures measured by differential scanning calorimetry. We suggest that T_tr is a better indicator of the glass transition than the temperature at which the total spectral width is 50 G, especially for large probes. The simulation program allowed the determination of the relative intensities of the fast and slow spectral components as a function of temperature; this information was used to clarify the redistribution of the probe above the glass transition of the SAN‐rich component in ABS systems. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 424–433, 2002; DOI 10.1002/polb.10110     

Microphase separation in poly(acrylonitrile–butadiene–styrene) (ABS) studied with paramagnetic spin probes. I. Electron spin resonance spectra

Microphase separation in poly(acrylonitrile–butadiene–styrene) (ABS) was studied as a function of the butadiene content and method of preparation with electron spin resonance (ESR) spectra of nitroxide spin probes. Results for the ABS polymers were evaluated by comparison with similar studies of the homopolymers polybutadiene (PB), polystyrene (PS), and polyacrylonitrile (PAN) and the copolymers poly(styrene‐co‐acrylonitrile) (SAN) and poly(styrene‐co‐butadiene) (SB). Two spin probes were selected for this study: 10‐doxylnonadecane (10DND) and 5‐doxyldecane (5DD). The probes varied in size and were selected because their hydrocarbon backbone made them compatible with the polymers studied. The ESR spectra were measured in the temperature range 120–420 K and were analyzed in terms of line shapes, line widths, and hyperfine splitting from the ¹⁴N nucleus; the appearance of more than one spectral component was taken as an indication of microphase separation. Only one spectral component was detected for 10DND in PB, PS, and PAN and in the copolymers SAN and SB. In contrast, two spectral components differing in their dynamic properties were detected for both probes in the three types of ABS samples studied and were assigned to spin probes located in butadiene‐rich domains (the fast component) and SAN‐rich domains (the slow component). The behavior of the fast component in ABS prepared by mass polymerization suggested that the low‐T_g (glass‐transition‐temperature) phase was almost pure PB. The corresponding phase in ABS prepared by emulsion grafting also contained styrene and acrylonitrile monomers. A redistribution of the spin probes on heating occurred with heating near the T_g of the SAN phase, suggesting that the ABS polymers as prepared were not in thermodynamic equilibrium. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 415–423, 2002; DOI 10.1002/polb.10109     

Recycling of ABS and PC from electrical and electronic waste. Effect of miscibility and previous degradation on final performance of industrial blends

The aim of this work, within the framework of polymer recycling, is to upgrade waste from electrical and electronic equipment. Blends of the two major residues were prepared via a melt blending process. These are ABS consisting of a SAN thermoplastic matrix with a dispersed elastomeric (polybutadiene rubber) component and polycarbonate (PC). The effect of partial miscibility and previous degradation levels was investigated. Mechanical characterization of ABS/PC systems was carried out to determine the optimum composition range. Previous degradation levels of the two wastes were investigated by FTIR and little degradation was found on ABS due to the presence of a polybutadiene rubber which is more sensitive to thermo-oxidative processes but no significant degradation was found on PC. Differential scanning calorimetry (DSC) tests demonstrated certain miscibility between the two components by identifying two glass transition temperatures. This partial miscibility, together with the small degradation of the elastomeric component, contributes to a low interaction promoting a decrease on mechanical performance. Scanning electron micrographs (SEM) showed the system morphology and certain lack of adherence along SAN/polybutadiene interface related to degradation of polybutadiene spheres which act as stress concentrators. The use of the equivalent box model (EBM) allowed to quantify the interaction level by determining an interaction/adherence parameter “A”, which turned to be lower than 1 and corroborated the lack of interaction.     

Association of polybutadiene living anions in cyclohexane

Simultaneous measurements of static and dynamic light scattering were made for cyclohexane solutions of living polybutadiene (PB) anion to characterize PB components existing in the solutions. There were two relaxation modes in the relaxation time spectra obtained by dynamic light scattering. The static structure factor and hydrodynamic radius of the major fast relaxation component obtained are explained by the unimer‐tetramer equilibrium model. The same model is also consistent with the data of the propagation reaction rate of the PB living anion in cyclohexane. The slow relaxation component is only minor (less than 1 wt %), but has a large radius of gyration of ca. 200 nm, and is assigned to aggregates consisting of a huge number of PB living anion chains. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1401–1407, 2005     

Photo-oxidation of polymers without light: Oxidation of polybutadiene and an ABS polyblend with singlet oxygen

In recent years much evidence has been accumulated to implicate electronically excited oxygen (¹Δ_g) molecules as the agent responsible in photosensitized oxidations for the formation of allylic hydroperoxides from olefins and of endoperoxides from 1,3-dienes. Little regarding the mechanistic aspects of the photo-oxidative degradation of polybutadiene (PBD) is known, however. To determine if electronically excited oxygen (¹Δ_g) molecules can oxidize PBD, the ABS polyblend and standard samples of PBD's containing high trans, high cis, and high vinyl content were treated in homogeneous solution at low temperature with chemically produced singlet oxygen in situ. The source of the singlet oxygen was the triphenylphosphite-ozone adduct. Studies by spectroscopy, elemental analysis, viscosity determinations, and gel measurements showed only the cis- and the trans-PBD were susceptible to oxidation; no chain scission was involved in the attack of cis- and trans-PBD by singlet oxygen; the oxidation of the cis PBD involved the initial formation of hydroperoxides which on thermal decomposition yielded gel. The trans-PBD was found to oxidize but apparently by a mechanism different from that of cis-PBD. Initial singlet oxygen attack of ABS proceeds by oxidation of the PBD portion of the polyblend. It was also observed that when only a small amount of the double bonds in the cis-PBD polymer had been oxidized to hydroperoxides, subsequent thermal treatment of this sample resulted in gross structural changes in the whole polymer.     

Clarification and discussion of chemical transformations involved in thermal and photo-oxidative degradation of ABS

The mechanisms of thermal and photo-oxidative degradation of unstabilized samples of ABS have been discussed in terms of the known chemistry of the unsaturated isomeric units of PB and the chemical species identified by either i.r. spectroscopy or chemical studies. The reactions which lead to the loss of unsaturation and loss of elastomeric properties of the rubber segment, production of hydroxyl and carbonyl species and the development of cross-linking and colour are extremely complex. High degree of correlation between the outlined chemical transformations and the identifiable reaction products has led to a more definitive and clearer mechanism of degradation of ABS, and by inference, PB and PB-based polyblends.     

Greffage de styrene et de styrene-acrylonitrile sur polybutadiene—comparaison des masses moléculaires

Polymerization of styrene in the presence of different types of polybutadiene leads to polystyrene (PS) grafted on to rubber and to free PS. It is shown that a difference in molecular weight exists between grafted and free PS; the molecular weight of grafted PS is systematically higher than that of free PS. A comparison to ABS systems has been made by grafting styrene and styrene-acrylonitrile in the same conditions on to polybutadiene. It appears that the difference in molecular weight between grafted and non-grafted polymer is much more pronounced in the case of ABS. These results can be explained by considering a decrease of the termination rate constant (k_t) in consequence of the local viscosity variations near the polybutadiene coils and by taking into account its preferential solvation by monomer and initiator.     

Effects of polybutadiene-g-SAN impact modifiers on the morphology and mechanical behaviors of ABS blends

A series of PB-g-SAN impact modifiers with different ratio of PB to SAN ranging from 20.6/79.4 to 91.9/8.1 were synthesized by seeded emulsion polymerization. ABS blends were prepared by blending these PB-g-SAN impact modifiers and SAN resin. The rubber concentration of these ABS blends was kept at a constant value of 15 wt%. The influences of different impact modifier on the mechanical behavior and morphology of ABS blends have been investigated. The dynamic mechanical analysis on ABS blends shows that T_g of the rubbery phase shifts to a lower temperature, (tan δ)_max of the rubbery phase increases and then decreases with the increase of PB concentration in PB-g-SAN impact modifier. A uniform dispersion of rubber particles in the matrix can be observed when PB/SAN ratio in PB-g-SAN impact modifier is in the range from 20.6/79.4 to 71.7/28.3. When it exceeds 71.7/28.3, an agglomeration of rubber particles occurs. The mechanical tests indicate that the ABS blend, in which PB/SAN ratio in the impact modifier is 71.7/28.3, has the maximum impact strength and yield strength.     

梳状聚丁二烯的合成及表征

以次氯酸叔丁酯为氯化剂,在无降解及交联情况下,向阴离子聚合的聚丁二烯主干引入活泼氯。氯化聚丁二烯与活性聚丁二烯阴离子(PB~(?))偶合得到支链沿主干无规分布的梳状聚丁二烯。降低偶合温度,提高[PB~(?)]/[Cl]比值及加入极性溶剂四氢呋喃,均有利于提高偶合接枝效率。渗透压法及GPC法的表征结果表明,沉淀分级净化产物为具有窄分子量分布主干及支链、结构确定的梳状聚丁二烯。其平均支链数可在较大范围内改变。     

Changes in the microstructure and morphology of high-impact polystyrene subjected to multiple processing and thermo-oxidative degradation

Multiple processing and thermo-oxidation have been employed to simulate the degradative processes to which high-impact polystyrene (HIPS) is subjected during processing, service life, and mechanical recycling. A curve-fitting procedure has been proposed for the analysis of the individual bands corresponding to polybutadiene microstructure resulting from Raman spectroscopy. The analysis of the glass transition relaxations associated with the polybutadiene (PB) and polystyrene (PS) phases has been performed according to the free-volume theory. Both reprocessing and thermo-oxidative degradation are responsible for complex physical and chemical effects on the microstructure and morphology of PB and polystyrene PS phases, which ultimately affect the macroscopic performance of HIPS. Multiple processing affects PB microstructure and the free-volume parameter associated with the PS phase. Physical ageing of the PS phase predominates for shorter exposure to thermo-oxidation; after prolonged exposure, however, the chemical effects on the PB phase become significant and strongly influence the overall structure.     

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.     

Morphological changes in SBS block copolymers caused by oil extension as determined by absolute small angle x-ray scattering

A series of SBS block copolymers diluted with different amounts (0–60 wt%) of three different kinds of oil were investigated: 1) lithene PM (a low molecular weight polybutadiene); 2) a paraffinic mineral oil with its electron density close to that of the polybutadiene (PB) phase; 3) a highly aromatic mineral oil with an electron density close to the polystyrene (PS) phase. All the oils seem to go into the polybutadiene matrix. Paraffinic oil and lithene form a homogeneous phase with PB; the aromatic oil at low concentrations mixes with the PB phase with a high level of inhomogeneity, while at higher concentration partial phase separation occurs. In the undiluted polymer, styrene forms cylinders in hexagonal packing. The distance between cylinders (about 43 nm) is not significantly changed upon dilution up to 33 wt%. Previously proposed changes in the morphology of PS domains at larger oil contents can be related to observed changes in the long period, in the segment length distributions, and in the homogeneities of the phase (density fluctuations). The electron density difference obtained for pure SBS is lower than the theoretical one calculated from the densities of pure PS and pure PB. Dilution by paraffinic oil improves the phase separation.     

Ion-free latex films composed of fused polybutadiene and poly (vinyl pyrrolidone) particles as polymer electrolyte materials

Latex films composed of fused polybutadiene (PB) and poly (vinyl pyrrolidone) (PVP) particles that contain no ionic, hydroxyl, or amino groups were swelled with lithium salt solutions to yield new polymer electrolyte materials. The latex particle consists of a nonpolar, rubbery core that contains the PB component and a polar, glassy shell that contains the PVP component. The particle core-shell morphology was retained in the solid state, after the latex dispersion medium was removed and the films dried at high temperatures, due to the high T_g of the PVP shell. The films swelled when immersed in lithium salt solutions, and ionic conductivity of swollen films was greater than 10^-3 S/cm. Swelling and ionic conduction occurred only in the polar PVP component. Extraction of PVP occurred with extended swelling. © 1994 John Wiley & Sons, Inc.     

Séparation d'un copolymère greffé de l'homopolymère correspondant par formation de gels réversibles perfectionnements et applications aux résines abs

From a mixture containing a graft copolymer A-B in the presence of homopolymers A and B, it is possible to separate for instance the homopolymer B, corresponding to the grafts, by the reversible gel technique. The reversible crosslinking is achieved by fixing selectively COONa groups on polymer A. Improvements of this separation method are proposed in the case of ABS resins, obtained by grafting styrene-acrylonitrile (SAN) copolymers on polybutadiene. Carboxylation of the polybutadiene part can be achieved, after grafting, by treatment with thioglycolic acid. The separation is performed for two different carboxy contents of the polybutadiene. The high efficiency of the separation is shown. It is also confirmed that there is no fractionation in composition of the graft copolymer during this separation.     

Graft copolymerization of methacrylic acid and acrylamide onto acrylonitrile-butadiene-styrene terpolymer by photoinduced hydroperoxide

Graft copolymerization of methacrylic acid (MAA) or acrylamide (AM) from an aqueous solution onto acrylonitrile-butadiene-styrene terpolymer (ABS) was initiated by the thermal decomposition of polymeric hydroperoxides, which are formed upon UV irradiationof ABS, which contains anthracene. Diffusion of anthracene at room temperature from a methanolic solution into ABS was affected by the acrylonitrile content ofABS.The graft yield was independent on the concentration of anthracene in the wide range of 0.03 X 10^-3 to 14.29 X 10^?3 mol/L in ABS. The graft polymerization reaction does not occur below 100°C.The effect of other variables, such as time of irradiation, intensity of UV, reaction time, and concentration of monomer in aqueous solution, on the amount of monomer grafted to ABS were also investigated.The contact angle significantly decreases upon grafting, indicating that the graft layer is on the surface of the polymer. © 1995 John Wiley & Sons, Inc.     

Photo-degradation and photo-stabilisation of the two-phase system poly(vinyl chloride)-polybutadiene

The photo-oxidative degradation of poly(vinyl chloride) (PVC)/polybutadiene (PB) blends has been studied. After uv irradiation, photo-grafting of the PVC and PB phases was observed. Photolysis of PVC accelerates cis-trans isomerisation of PB. Both phases, PVC and PB, are photo-degraded according to free radical oxidation mechanisms. The rates of these processes can be decreased by the addition of metal chelates, such as commercially produced Cyasorb uv light absorber 1084 (2,2′-thiobis(4-t-octylphenolato)-n-butylamine nickel(II)) and Cyasorb uv light absorber 2548 (cobalt dicyclohexyldithiophosphinate).     

Aspects of degradation and stability of ABS copolymers. I. Effect of β-carotene as antioxidant

The oxidative degradation of polybutadiene–styrene–acrylonitrile (ABS) copolymer was extensively investigated. Three factors were studied: the influence of ageing temperature on the rate of the oxidation of the copolymer; the efficiency of β-carotene as chain breaking antioxidant; and the effect of butadiene content on the rate of the oxidative degradation of the ABS copolymer.     

溶聚丁苯链化学结构的NMR研究

溶聚丁苯链化学结构的NMR研究;溶聚丁苯; 链化学结构; 相容性     

Synthesis of well‐defined comb‐like graft (co)polymers by nucleophilic substitution reaction between living polymers and polyhalohydrocarbon

A series of graft (co)polymers were synthesized by nucleophilic substitution reaction between iodinated 1,2‐polybutadiene (PB‐I, backbone) and living polymer lithium (side chains). The coupling reaction between PB‐I and living polymers can finish within minutes at room temperature, and high conversion (up to 92%) could be obtained by effectively avoiding side reaction of dimerization when living polymers were capped with 1,1‐diphenylethylene. By virtue of living anionic polymerization, backbone length, side chain length, and side chain composition, as well as graft density, were well controlled. Tunable molecular weight of graft (co)polymers with narrow molecular weight distribution can be obtained by changing either the lengths of side chain and backbone, or the graft density. Graft copolymers could also be synthesized with side chains of multicomponent polymers, such as block polymer (polystyrene‐b‐polybutadiene) and even mixed polymers (polystyrene and polybutadiene) as hetero chains. Thus, based on living anionic polymerization, this work provides a facile way for modular synthesis of graft (co)polymers via nucleophilic substitution reaction between living polymers and polyhalohydrocarbon (PB‐I). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013