SAN Content Research Articles

Effect of blend composition and organoclay loading on the nanocomposite structure and properties of miscible poly(methyl methacrylate)/poly(styrene-co -acrylonitrile) blends

Organically-modified montmorillonite clay nanocomposites of poly(styrene-co-acrylonitrile) (SAN), poly(methyl methacrylate) (PMMA) and SAN/PMMA miscible blend are investigated. Structure characteristics at the nanoscale and microscale and thermal and tensile properties are studied as a function of polymer blend composition and filler loading fraction. Blend miscibility and Tg are unaffected by up to 10% by wt. organoclay. Thermal degradation stability increases with SAN content and exhibits an optimum value of clay loading. Stiffness shows significant improvement. Tensile strength and elongation-at-break suffer as a result of nanocomposite formation. Modulus shows a maximum enhancement of 57% (5 ± 0.06 GPa at 10 wt% filler, 20/80 SAN/PMMA) and varies linearly with clay fraction for all compositions of matrix phase. Predictions of Halpin–Tsai composite model are in excellent agreement with the experimental behavior over full range of polymer blend composition. Fundamental aspects of a polymer blend–clay nanocomposite are clarified, such as lack of additional synergy between clay platelets and matrix, and tensile ductility reduction, compared with polymer–clay system. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Influence of blend composition on the mechanical properties and morphology of PC/ASA/SAN ternary blends

Bisphenol A polycarbonate/acrylonitrile–styrene–acrylic/styrene–acrylonitrile copolymer (PC/ASA/SAN) ternary blends were prepared over a range of compositions via mixing PC, SAN, and ASA copolymer by melt blending. An analysis was made on the mechanical properties and morphology of the blends. Special care was taken to make comparisons of the morphologies and properties of blends with different SAN content. When a small amount SAN was introduced to PC/ASA blends, the dispersion condition of ASA in the matrix was improved and a better integrated mechanical properties was realized. Further increasing the SAN content led to a decrease of impact strength, which was due to the changing of the morphology of the blends and the inherent brittleness of matrix. The study about the effect of ASA content on the properties of PC/ASA/SAN blends showed that the blend with 20 wt% ASA had good mechanical properties.

Crystallization behavior and hydrophilicity of poly (vinylidene fluoride) (PVDF)/poly (styrene-co-acrylonitrile) (SAN) blends

Poly (styrene-co-acrylonitrile) (SAN) is a hydrophilic non-crystalline copolymer, which is initially used in this paper to improve the hydrophilicity of poly (vinylidene fluoride) (PVDF). Investigation of the crystallization behavior of PVDF/SAN blends showed that the samples presented only α phase regardless of SAN content as cooling from the melt. A double-melting phenomenon was related to the perfection or crystal size of PVDF crystals. As the SAN content is increasing, crystallization of PVDF was limited, leading to a decreased crystallinity and lamellar growth. Besides, the hydrophilicity of PVDF was improved by blending with SAN. The sample containing 70 wt.% SAN performed a similar surface property of the neat SAN owing to the besieging of the PVDF phase by SAN. Observed from the cross section of the blends, PVDF/SAN blends were partially miscible with less than 50 wt.% SAN addition. As the SAN content was more than 50 wt.%, the crystalline PVDF particles clearly dispersed in the amorphous matrix.

Viscoelastic properties of blends of poly(methyl methacrylate) and poly(styrene-co-acrylonitrile) having various acrylonitrile contents

Dynamic viscoelastic properties of blends of poly(methyl methacrylate) (PMMA) and poly(styrene-co-acrylonitrile) (SAN) with various AN contents were measured to evaluate the influence of SAN composition, consequently χ parameter, upon the melt rheology. PMMA/SAN blends were miscible and exhibited a terminal flow region characterized by Newtonian flow, when the acrylonitrile (AN) content of SAN ranges from 10 to 27 wt %. Whereas, PMMA/SAN blends were immiscible and exhibited a long time relaxation, when the AN content in SAN is less than several wt % or greater than 30 wt %. Correspondingly, melt rheology of the blends was characterized by the plots of storage modulus G′ against loss modulus G″. Log G′ versus log G″ plots exhibited a straight line of slope 2 for the miscible blends, but did not show a straight line for the immiscible blends because of their long time relaxation mechanism. The plateau modulus, determined as the storage modulus G′ in the plateau zone at the frequency where tan δ is at maximum, varied linearly with the AN content of SAN irrespective of blend miscibility. This result indicates that the additivity rule holds well for the entanglement molecular weights in miscible PMMA/SAN blends. However, the entanglement molecular weights in immiscible blends should have “apparent” values, because the above method to determine the plateau modulus is not applicable for the immiscible blends. Effect of χ parameter on the plateau modulus of the miscible blends could not be found. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Morphology and Thermal Behavior of MCPA6/SAN Blends Prepared by Anionic Ring-Opening Polymerization of ε-caprolactam

In this article, a series of blends of monomer casting polyamide 6 and styrene-co-acrylonitrile (MCPA6/SAN) were prepared by in situ anionic ring-opening polymerization of e-caprolactam (CL). Their morphology and thermal behaviors were investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide-angle x-ray diffraction (WAXD), respectively. The SAN phase had much finer domain in MCPA6/SAN than that in the polyamide6/SAN (PA6/SAN) blends prepared by melt blending of PA6 and SAN. All the melting and crystallization parameters of MCPA6/SAN blends decreased gradually with the increase of SAN content, while the melting temperature was almost unchanged. These results were due to the hydrolysis reaction of SAN occurred during the anionic polymerization of e-caprolactam (CL). In addition, WAXD results showed that only α crystal forms existed in the MCPA6/SAN blends.

Brittle‐Ductile Transition in Reactive PBT/SAN Blends

AbstractToughening of reactive poly(butylene terephthalate) (PBT)/styrene‐acrylonitrile copolymer (SAN) blends was studied. PBT/SAN with glycidyl methacrylate (SAN‐GMA) (70/30) behaved in ductile manner on tensile test, while PBT/SAN (70/30) blend failed in brittle manner. Additionally, poly[methylene (phenylene isocyanate)] (PMPI) was added to the PBT/SAN‐GMA blend, where it was expected that PMPI would assist the reaction between PBT and SAN‐GMA, and then the strain at break was improved. PBT/SAN/PMPI (70/30/4) also behaved in ductile manner, although the interfacial adhesion strength between matrix and dispersed phase was extremely weaker than that in PBT/SAN‐GMA blend. From the results, it was found that PMPI acted as a compatibilizer without copolymer formation at the interface and then PBT/SAN behaved in ductile manner in higher SAN content by PMPI effect.

Morphology and thermal behavior of MCPA6/SAN blends prepared by anionic ring‐opening polymerization of ϵ‐caprolactam

AbstractIn this article, a series of blends of monomer casting polyamide 6 and styrene‐co‐acrylonitrile (MCPA6/SAN) were prepared by in situ anionic ring‐opening polymerization of ϵ‐caprolactam. Their morphology and thermal behaviors were investigated by means of scanning electron microscope, differential scanning calorimeter, and wide‐angle X‐ray diffraction (WAXD), respectively. The SAN phase had much finer domain in MCPA6/SAN than that in the PA6/SAN blends prepared by melt blending of PA6 and SAN. All the melting and crystallization parameters of MCPA6/SAN blends decreased gradually with the increase of SAN content, while the melting temperature was almost unchanged. These results were due to the hydrolysis reaction of SAN that occurred during the anionic polymerization of ϵ‐caprolactam. In addition, WAXD results showed that only α crystal forms existed in the MCPA6/SAN blends. In addition, the mechanical property of MCPA6 was improved obviously by incorporating a certain amount of SAN. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1357–1363, 2006

Reactive Extrusion of SAN/EPDM Blends

Abstract The blending of styrene-acrylonitrile copolymer (SAN) and three different types of ethylene-propylene-diene terpolymer (EPDM) by reactive extrusion was studied and the free radical initiators: 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane (Luperco 101 XL), 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3 (Luperco 130 XL), α,α′-di(t-butylperoxy)diisopropyl-benzene (Peroximon F40) and 2,2-azo-di-(2-acetoxy)propane (Luazo AP) were used. Besides, structural characteristics of the obtained blends, some rheological and mechanical properties were also established. The rheological behavior was determined using rheometer and corotating extruder. Measurements of mechanical properties included: tensile strength, impact strength and elongation at break have been made. Blends were separated on its structural components SAN, EPDM, graft (EPDM-g-SAN) and gel content, which were further characterized by solution viscosimetry and IR spectrophotometry. The obtained results elucidate the reactions that occur during extrusion process. The dominant grafting reaction was observed in blends prepared by using a Peroximon F40 as an initiator also showing outstanding mechanical and processing characteristics.

Enzymatic degradation of blends of poly(ε‐caprolactone) and poly(styrene‐co‐acrylonitrile) by Pseudomonas lipase

AbstractIn polymer blends, the composition and microcrystalline structure of the blend near surfaces can be markedly different from the bulk properties. In this study, the enzymatic degradation of poly(ε‐caprolactone) (PCL) and its blends with poly(styrene‐co‐acrylonitrile) (SAN) was conducted in a phosphate buffer solution containing Pseudomonas lipase, and the degradation behavior was correlated with the surface properties and crystalline microstructure of the blends. The enzymatic degradation preferentially took place at the amorphous part of PCL film. The melt‐quenched PCL film with low crystallinity and small lamellar thickness showed a higher degradation rate compared with isothermally crystallized (at 36, 40, and 44°C) PCL films. Also, there was a vast difference in the enzymatic degradation behavior of pure PCL and PCL/SAN blends. The pure PCL showed 100% weight loss in a very short time (i.e., 72 h), whereas the PCL/SAN blend containing just 1% SAN showed ∼50% weight loss and the degradation ceased, and the blend containing 40% SAN showed almost no weight loss. These results suggest that as degradation proceeds, the nondegradable SAN content increases at the surface of PCL/SAN films and prevents the lipase from attacking the biodegradable PCL chains. This phenomenon was observed even for a very high PCL content in the blend samples. In the blend with low PCL content, the inaccessibility of the amorphous interphase with high SAN content prevented the attack of lipase on the lamellae of PCL. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 868–879, 2002

Reactive Compatibilization of SAN/EPR Blends. 2. Effect of Type and Content of Reactive Groups Randomly Attached to SAN

Kinetics of the poly(styrene-co-acrylonitrile)/poly(ethylene-co-propylene) (SAN/EPR) interfacial reaction has been varied by changing both the average number of reactive groups per SAN chain and the content of reactive SAN in the SAN phase, while keeping constant the overall SAN/EPR composition, i.e., 75/25 w/w. For this purpose, reactive SAN chains containing 0.004, 0.028, 0.049, and 0.078 mol/wt % of either primary amine or carbamate (an amine precursor) have been synthesized, and the content of reactive SAN in the SAN phase has been changed from 2.5 to 73.33 wt %. It appears that the number and type of reactive groups attached onto SAN affect not only the extent of the compatibilization reaction but also the compatibilization capability of the in situ formed graft copolymer in a strong dependence on molecular weight and molecular architecture.

Physical aging behavior of miscible blends of poly(methyl methacrylate) and poly(styrene-co-acrylonitrile)

The influence of blend composition on volume relaxation behavior was determined for miscible blends of poly(methyl methacrylate) (PMMA) and poly(styrene-co-acrylonitrile) (SAN). The volume relaxation rates displayed an approximately linear dependence on blend composition for all of the aging temperatures employed which were 15, 30, and 45°C below Tg. No unique behavior was observed for the blends compared to the pure polymers in terms of glass transition fragility observed by differential scanning calorimetry or the variation of density with composition. The dynamic mechanical β-relaxation process for PMMA was observed in the PMMA/SAN blends, and the intensity of the relaxation diminished with increasing SAN content. These results were contrasted with previous findings by the present authors on blends of atactic polystyrene (a-PS) with poly(2,6-dimethyl phenylene oxide) (PPO). Fragility, density, and secondary relaxation features of the PMMA/SAN and a-PS/PPO blends were influenced by the respective nature of interactions in these mixtures, and the volume relaxation rates were consistent with these characteristics. An apparent failure of time–aging time superposition was noted for PMMA due to overlapping α- and β-relaxations.

Melt Viscosities and Mechanical Properties of PC/SAN Blends

Melt viscosities and mechanical properties of polycarbonate (PC), styrene-acrylonitrile copolymer (SAN), and their blends were studied. PC and SAN were melt blended at different compositions using a single screw extruder. Melt viscosities were measured with a capillary rheometer. The melt viscosity test showed that increasing the PC content increases the viscosity of the blends, and melt viscosities of blends are intermediate between the values of PC and SAN. Standard mechanical property tests were performed on injection molded ASTM test specimens. Tensile strength and modulus increase but elongation at break decreases when the SAN content increases. Notched Izod impact strength decreases rapidly with the addition of SAN into PC. Unnotched impact strength is higher than notched impact strength and is less sensitive to the addition of SAN.

Miscibility, morphology and fracture toughness of tetrafunctional epoxy resin/poly (styrene-co-acrylonitrile) blends

Poly(styrene-co-acrylonitrile) (SAN) was found to be miscible with the tetraglycidylether of 4,4'-diaminodiphenylmethane (TGDDM), as shown by the existence of a single glass transition temperature (Tg) over the whole composition range. However, SAN was found to be immiscible with the 4,4′-diaminodiphenylmethane (DDM)-cured TGDDM. Dynamic mechanical analysis (DMA) shows that the DDM-cured TGDDM/SAN blends have two Tgs. A scanning electron microscopy (SEM) study revealed that all the DDM-cured TGDDM/SAN blends have a two-phase structure. The fracture toughness KIC of the blends increased with SAN content and showed a maximum at 10 wt% SAN content, followed by a dramatic decrease for the cured blends containing 15 wt% SAN or more. The SEM investigation of the KIC fracture surfaces indicated that the toughening effect of the SAN-modified epoxy resin was greatly dependent on the morphological structures.

Morphology and physical properties of SAN/NBR blends: The effect of AN content and melt viscosity of SAN

To study the effect of dispersed poly(butadiene-co-acrylonitrile) (NBR) rubber size on the physical properties of poly(styrene-co-acrylonitrile) (SAN)/NBR blends, SANs with various melt viscosities and acrylonitrile (AN) contents were examined. The dispersed size of NBR, whose AN content is 30 wt %, was reduced as the melt viscosity of the SAN matrix was increased or as the AN content of the SAN matrix was reduced in the range of 19–32 wt %. As the melt viscosity of the SAN matrix was increased, the damping peak of the NBR phase moved to a higher temperature, and as the AN content of SAN was reduced, the damping peak of the SAN phase moved to a lower temperature. Higher values of impact strength and elongation at break and reduced yield behavior at a low shear rate were observed at a finer dispersion of NBR. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 935–941, 1999

A polymer of bisphenol A and bisphenol A diglycidyl ether and its blends with poly(styrene-co-acrylonitrile):In situ polymerization preparation, morphology, and mechanical properties

The poly(hydroxy ether of bisphenol A)-based blends containing poly(acrylontrile-co-styrene) (SAN) were prepared through in situ polymerization, i.e., the melt polymerization between the diglycidy ether of bisphenol A (DGEBA) and bisphenol A in the presence of poly(acrylontrile-co-styrene) (SAN). The polymerization reaction started from the initial homogeneous ternary mixture of SAN/DGEBA/bisphenol A, and the phenoxy/SAN blends with SAN content up to 20 wt % were obtained. Both the solubility behavior and Fourier transform infrared (FTIR) spectroscopy studies demonstrate that no intercomponent reaction occurred in the reactive blend system. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electronic microscopy (SEM) were employed to characterize the phase structure of the as-polymerized blends. All the blends display the separate glass transition temperatures (Tg's); i.e., the blends were phase-separated. The morphological observation showed that all the blends exhibited well-distributed phase-separated morphology. For the blends with SAN content less than 15 wt %, very fine SAN spherical particles (1–3 μmm in diameter) were uniformly dispersed in a continuous matrix of phenoxy and the fine morphology was formed through phase separation induced by polymerization. Mechanical tests show that the blends containing 5–15 wt % SAN displayed a substantial improvement of tensile properties and Izod impact strength, which were in marked contrast to those of the materials prepared via conventional methods. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 525–532, 1999

Compatibility enhancement of ABS/PVC blends

The compatibilizing effect of poly(styrene-co-acrylonitrile) (SAN) whose acrylonitrile (AN) content is 25 wt % (SAN 25) in poly(acrylonitrile-co-butadiene-co-styrene) (ABS)/poly(vinyl chloride) (PVC) blend was studied when the AN content of the matrix SAN in ABS was 35 wt % (SAN 35). When some amount of matrix SAN 35 was replaced by SAN 25 in a ABS/PVC (50/50 by weight) blend, the mixed phase of SAN and PVC at the interface was thickened, and about a twofold increase of impact strength was observed. The changes in morphology, dynamic mechanical properties, and rheological properties by the compatibilizing effect of SAN 25 were observed. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 705–709, 1998

Compatibility enhancement of ABS/PVC blends

ABSTRACT: The compatibilizing effect of poly(styrene- co -acrylonitrile) (SAN) whoseacrylonitrile (AN) content is 25 wt % (SAN 25) in poly(acrylonitrile- co -butadiene- co -styrene) (ABS)/poly(vinyl chloride) (PVC) blend was studied when the AN content of thematrix SAN in ABS was 35 wt % (SAN 35). When some amount of matrix SAN 35 wasreplaced by SAN 25 in a ABS/PVC (50/50 by weight) blend, the mixed phase of SAN andPVC at the interface was thickened, and about a twofold increase of impact strengthwas observed. The changes in morphology, dynamic mechanical properties, and rheo-logical properties by the compatibilizing effect of SAN 25 were observed. © 1998 JohnWiley & Sons, Inc. J Appl Polym Sci 70: 705–709, 1998 Key words: ABS; SAN; PVC; blend; compatibilizer; impact strength; morphology;thermal property; dynamic mechanical property; rheological property INTRODUCTION Polymer blends can combine attractive propertiesof several polymers into one, or can improve defi-cient characteristics of a particular polymer.However, immiscible blends often have poor me-chanical properties compared to their compo-nents. It is well known that the introduction of asmall amount of compatibilizer can lead to majorchanges in mechanical properties.

Effect of the type of SAN in SAN/CPE blend: Morphology, mechanical, and rheological properties

The effect of the molecular weight and acrylonitrile (AN) content of the styrene-acylonitrile copolymer (SAN) on the morphology, mechanical, and rheological properties of SAN/chlorinated polyethylene (CPE) blends was studied. The interaction between dispersed particle and matrix is expected to be optimal at the 25% AN content of SAN. Phase inversion from a dispersion to a continuous phase appears to occur above 50 wt % CPE. Mechanical properties increased with molecular weight at a constant AN content of SAN. Morphological, mechanical, and rheological properties were more sensitive to the AN content, rather than the molecular weight of SAN. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 27–36, 1998

Self-Similar Relaxation Behavior at the Gel Point of a Blend of a Cross-Linking Poly(ε-caprolactone) Diol with a Poly(styrene-co-acrylonitrile)

Novel polymer properties can be achieved by blending high molecular weight linear chains into a cross-linking system of short linear chains. This study is concerned with the rheological properties that are dominated at first by the highly entangled linear chains. However, with increasing extent of cross-linking, the short chains connect into a network structure and begin to dominate the rheology. The material here consists of cross-linking poly(-caprolactone) diol (PCL) and up to 40% of linear poly- (styrene-co-acrylonitrile) (SAN) of high molecular weight. The blend was molecularly mixed before cross- linking. Three competing processes determine the structure of the system, (1) chemical cross-linking of the low molecular weight species into a sample spanning network of interpenetrating chains, (2) fluctuations in composition due to phase separation at increasing extents of reaction, and (3) crystallization of the PCL, which we tried to suppress as much as possible. At the gel point, systems with low SAN content show the typical scaling behavior of the critical gel with a self-similar relaxation spectrum, H(I) ) Go/i(n )( I / I o ) - n , I > I o, at low probing frequencies, ˆ < 1/Io. However, for the systems with high concentrations of the inert component, the self-similar region did not develop, possibly due to the phase separation induced by the cross-linking. The relaxation exponent, n, decreased with increasing concentration of the highly entangled linear component. The results suggest that dynamic mechanical methods are applicable for determination of the gel point for homogeneous semi-IPN systems.

Crystallization Kinetics in Mixtures of Poly(ε-caprolactone) and Poly(styrene-co-acrylonitrile)

Isothermal crystallization kinetics in the miscible mixtures of poly(ε-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) have been investigated as a function of the composition and the crystallization temperature by optical microscopy. The radial growth rates of the spherulites have been described by a kinetic equation including the interaction parameter and the free energy for the formation of secondary crystal nuclei. Fold surface free energies decrease slightly with the increase of SAN content. The experimental findings show that the influence of the glass transition temperature of the mixture, which is related to the chain mobility, on the rate of crystallization predominates over the influence of the surface free energies. This indicates that the glass transition temperature of the mixture should be of more importance, so that the growth rates decrease when the content of the noncrystallizable component increases. In addition, the Flory−Huggins interaction parameter obtained by fitting the kinetic equation with experimental data is questionable.