Compatibilization of poly(ethylene-co-vinyl alcohol) (EVOH) and EVOH–HDPE blends: Structure and properties

Hydrogenated and maleated S-B-S block copolymer (SEBS-g-MA) was applied as a compatibilizer in melt-mixed binary blends with poly(ethylene-co-vinyl alcohol) (EVOH) and in ternaries containing high-density polyethylene (HDPE) as the major component. The techniques applied were dynamic, mechanical, and tensile testing; differential thermal analysis; Fourier transform infrared spectroscopy; and optical and electron microscopy (SEM). Small and large deformation behavior under dynamic and static mode, coupled with other physical characterization data, as well as morphological evidence, demonstrated that SEBS-g-MA is an efficient compatibilizer in the binary and ternary blends. In the latter, its function is the coupling of EVOH with the HDPE matrix, thus reducing the moisture sensitivity of the former and the improvement of performance-to-cost ratio of the final product. After leaching out EVOH from the ternaries, morphology examination of the cross section of films, showed a laminar EVOH phase distribution, a feature desirable in barrier materials applications. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 589–596, 1998     

In situ compatibilization of polystyrene and polyurethane blends by using poly(styrene-co-maleic anhydride) as reactive compatibilizer

Blends of polystyrene (PS) and polyurethane (PU) elastomer were obtained by melt mixing, using poly(styrene-co-maleic anhydride) (SMA) containing 7 wt % of maleic anhydride groups as a reactive compatibilizer. Polyurethanes containing polyester flexible segments, PU-es, and polyether flexible segments, PU-et, were used. These polyurethanes were crosslinked with dicumyl peroxide or sulfur to improve their mechanical properties. The anhydride groups of SMA can react with the PU groups and form an in situ graft copolymer at the interface of the blends during their preparation. The rheological behavior was accompanied by torque versus time curves and an increase in the torque during the melt mixing was observed for all the reactive blends, indicating the occurrence of a reaction. Solubility tests, gel permeation chromatography, and scanning electronic microscopy confirmed the formation of a graft copolymer generated in situ during the melt blending. These results also indicate that this graft copolymer contains C C bond between SMA and PU chains. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2514–2524, 2001     

Structure and properties of starch/poly(ethylene-co-vinyl alcohol) blown films

Blends of native corn starch and poly(ethylene-co-vinyl alcohol) (EVOH), with starch: EVOH ratios of 1 : 1 (SE-50) and 2 : 1 (SE-67A, SE-67B), were processed into blown films. SE-67A had a higher glycerol and water content and was processed at 5°C higher than was SE-67B. The films were conditioned to various moisture contents by equilibrating at a constant relative humidity and by oven drying at 41°C. Equilibrium moisture content, which ranged from 2 to 11%, increased with increasing starch content at a given relative humidity. Mechanical properties depended strongly on starch and moisture content as well as on processing history. The extension to break of SE-50 was only about one-third that of EVOH, while that of the 2 : 1 blends was even lower. SE-67A exhibited a higher extension to break, lower tensile strength and modulus, and greater moisture sensitivity than those of SE-67B. Differential scanning calorimetry and dynamic mechanical analysis revealed evidence of interactions between starch and EVOH, probably indicative of extensive intermixing but not necessarily miscibility. Scanning electron micrographs of fracture surfaces revealed extensive differences in texture with microcracking in SE-50 and SE-67A. The combination of the analytical results provide a basis for explaining many aspects of the mechanical behavior including the marked difference in properties between SE-67A and SE-67B. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2613–2622, 1997     

Phase Behaviour of Poly(ethylene oxide)/Poly(styrene-co-maleic anhydride) Blends

Thermal behaviour and morphology of blends of poly(ethylene oxide) (PEO) and poly(styrene-co-maleic anhydride) (SMA) prepared by the coprecipitation technique were studied by means of differential scanning calorimetry, optical microscopy and thermogravimetry. SMA containing 25wt% maleic anhydride (MA) was found to be miscible with PEO when the SMA content was greater than 80%. The melting temperature and crystallinity depended on the composition of the blend. SMA appears to segregate interlamellarly during the isothermal crystallization of PEO. The thermal stability of blends was enhanced and was higher than that of pure PEO and SMA. © of SCI.     

Impact-modified poly(styrene-co-acrylonitrile) blends containing both oxazoline-functionalized poly(ethene-co-1-octene) elastomers and poly(styrene-co-maleic anhydride) as compatibilizer

Blends of a poly(styrene-co-acrylonitrile) (SAN) with poly(ethene-co-1-octene) rubber (EOR) were investigated. An improved toughness–stiffness balance was obtained when adding as a compatibilizer a blend consisting of oxazoline-functionalized EOR, prepared by grafting EOR with oxazoline-functional maleinate, and poly(styrene-co-maleic anhydride) (SMA), which is miscible with SAN. Enhanced interfacial adhesion was evidenced by the improved dispersion of the EOR in the SAN matrix and the reduced glass transition temperature of the dispersed EOR phase. Morphology studies using transmission electron microscopy revealed formation of an interphase between the matrix and the rubber particles. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1685–1695, 1999     

Morphology and mechanical properties of pullulan/poly(vinyl alcohol) blends crosslinked with glyoxal

We prepared pullulan/poly(vinyl alcohol) (PVA) blend films by casting the polymer solution in dimethyl sulfoxide. Their morphology and mechanical properties were investigated. Scanning electron micrographs revealed that the pullulan was immiscible with PVA over the entire composition range. The tensile strength and modulus of the blend films were lower than those predicted by the upper bound composite equation. To improve the mechanical properties, we investigated the reaction of the 40/60 blend with glyoxal. The infrared spectral change and the increase in the glass‐transition temperature (corresponding to the PVA component) accompanying the reaction indicated that crosslinking with glyoxal had proceeded. The crosslinked films were homogeneous and had higher tensile strengths and moduli than the simple blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2273–2280, 2001     

环氧化三元乙丙胶与苯乙烯—马来酸酐共聚物的共混行为研究

利用反应共混技术实现了环氧化三元乙丙橡胶（e-EPDM）对苯乙烯－马来酸酐（SMA）共聚物的增韧改性。以EPDM／SMA共混体系为参比,考察了共混物结构、流变行为、冲击性能和断面形态。结果表明,e－EPDM与SMA反应共混可原位形成偶联接枝产物,改善共混体系的相容程度,提高SMA的韧性。     

Reactive processing and properties of styrene–maleic anhydride and poly(tetramethylene ether glycol)

The anhydride/hydroxyl‐functionalized blends of styrene–maleic anhydride (SMAH) with poly(tetramethylene ether glycol) (PTMEG) in the presence or absence of a hydrated zinc acetate catalyst were produced in a batch mixer and in a corotating twin‐screw extruder. In batch mixing, torque values increased with time as a result of chain‐extension/branching reactions. The reaction products were studied by thermal, mechanical, morphological, and spectroscopic characterization techniques. The glass transition temperature of SMAH was lowered by the addition of PTMEG into the system. Major morphological changes were observed at the initial stages of extrusion. The changes in the screw speed influenced the mechanical properties and morphology of the blends. SMAH/PTMEG blends were brittle due to the glassy nature of SMAH. FTIR analysis of the SMAH/PTMEG system showed carboxylic acid and ester formation in the extrusion experiments. Mechanical property data and FTIR spectra indicated that at 150 rpm chain‐extension/branching reactions were maximized due to ester formation. However, at 220 rpm, a lower extent of ester formation was observed due to the lower residence time in the extruder. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2148–2156, 2002     

Melt processing,mechanical, and fatigue crack propagation properties of reactively compatibilized blends of polyamide 6 and acrylonitrile–butadiene–styrene copolymer

Within a IUPAC study, melt processing, mechanical, and fatigue crack growth properties of blends of polyamide 6 (PA 6) and poly(acrylonitrile–butadiene–styrene) (ABS) were investigated. We focused on the influence of reactive compatibilization on blend properties using a styrene–acrylonitrile–maleic anhydride random terpolymer (SANMA). Two series of PA 6/ABS blends with 30 wt % PA 6 and 70 wt % PA 6, respectively, were prepared with varying amounts of SANMA. Our experiments revealed that the morphology of the matrix (PA 6 or ABS) strongly affects the blend properties. The viscosity of PA 6/ABS blends monotonically increases with SANMA concentration because of the formation of high‐molecular weight graft copolymers. The extrudate swell of the blends was much larger than that of neat PA 6 and ABS and decreased with increasing SANMA concentrations at a constant extrusion pressure. This observation can be explained by the effect of the capillary number. The fracture resistance of these blends, including specific work to break and impact strength, is lower than that of PA 6 or ABS alone, but increases with SANMA concentration. This effect is most strongly pronounced for blends with 70 wt % PA 6. Fatigue crack growth experiments showed that the addition of 1–2 wt % SANMA enhances the resistance against crack propagation for ABS‐based blends. The correlation between blend composition, morphology and processing/end‐use properties of reactively compatibilized PA 6/ABS blends is discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

静电纺丝制备苯乙烯马来酸酐共聚物纳米纤维及其固定化b-D-半乳糖苷酶

采用静电纺丝技术制备苯乙烯-马来酸酐共聚物纳米纤维,最佳电纺条件为：聚合物浓度0.35 g/mL、针尖到接收板距离25 cm、电纺液流量250 mL/h、电压21 kV. 该条件下获得了直径约300 nm且分布均一的纳米纤维. 利用该纳米纤维固定b-D-半乳糖苷酶,固定化反应的最适pH值为4.0,此时酶负载量为(15.1±0.5) mg/g. 固定化酶催化2-硝基苯酚-b-D-半乳吡喃糖苷水解反应的米氏常数Km=2.7 mmol/L,略大于游离酶的Km值(2.2 mmol/L);最大反应速率Vmax为97.2 mmol/(min×mg),为游离酶的47.8%. 固定化酶在37℃下重复操作21次后活性损失仅为15%. 在连续搅拌式反应器中将固定化酶用于催化乳糖的水解反应,连续使用17 d仍能稳定运行.     

Reactive melt blends of nylon with poly(styrene-co-maleic anhydride)

Melt blends of nylon with poly(styrene-co-maleic anhydride) (SMA) were prepared in a twin-screw extruder. Viscoelastic properties of the melt and morphological, thermal, and mechanical properties of the blends were determined. Fourier-transform infrared (FTIR) spectroscopy measurement indicated reactions between nylon and SMA. Melting peak temperature (T_m) of nylon was not changed in blends. This, together with the FTIR results, assured that the reactions occur mainly with the free amide end groups of nylon. Melt viscosity, elasticity, and the heat-distortion temperature (HDT) of nylon was significantly increased with the addition of SMA. Tensile strength and impact strength of nylon were, respectively, in general, increased and decreased with SMA.     

Physical modification of polypropylene. III. Novel morphology of polypropylene and poly(ethylene-co-vinyl alcohol) with epoxy blend fibers

In this study, the novel morphology of polypropylene (PP) and poly(ethylene-co-vinyl alcohol) (EVOH) blend fibers is described. More precisely, the blend fibers of PP–EVOH containing a small amount of EVOH (1, 3, 5, 7, and 9% by weight), with and without epoxy (1 wt %), have been melt-spun at a constant spinning velocity (500 m/min). For the as-spun fiber, both the initial modulus and the tenacity increased with the increase in the EVOH content. The blend fibers with three draw ratios (2, 3, and 4) drawn at room temperature. The scanning electron microscopic study showed that a draw ratio of 2 reveals little about the morphological changes, whereas a draw ratio of 4 showed a streak structure perpendicular to the fiber axis for PP–EVOH (91/9 wt %) blend fibers. In addition, epoxy (1 wt %) containing PP–EVOH (91/9 wt %) blend fiber showed latitudinal streaks. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1049–1057, 1999     

Synthesis and processing of the (ethylene-vinyl acetate-vinyl alcohol) terpolymer and its blends with a polyamide and styrene copolymers

In this article, the synthesis and properties of the (ethylene-vinyl acetate-vinyl alcohol) terpolymer are studied in detail. A transesterification reaction with alcohols was conducted on poly(ethylene-vinyl acetate) to obtain terpolymers with varying hydroxide contents through three different routes: in solution, in a mixing chamber, and in a twin-screw extruder. The kinetics of the reaction in the mixing chamber are compared with those of the twin-screw extruder. Mechanical and rheological properties of the terpolymer are examined as a function of conversion. Blends of the terpolymer with polyamide (Nylon-6) were prepared for various compositions. They show a steep reduction in the equilibrium torque with respect to that of the polyamide. A region of compatibility at high polyamide contents gives rise to an increase of some mechanical properties above the simple mixing rule (Young's modulus). On the other hand, blends with poly(styrene-acrylonitrile) and poly(styrene maleic anhydride) show a region of compatibility at equal proportions of the styrene copolymers and with 10% terpolymer content, induced by the reaction of the hydroxide and maleic anhydride groups. This reaction is inhibited at high styrene-acrylonitrile concentrations due to interference presented by the effect of interactions between the maleic anhydride and acrylonitrile groups. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1071–1083, 1998     

Reactive compatibilization of polystyrene/poly(ethylene–co–vinyl acetate) (EVA) blends

A reactive compatibilizer, mercapto‐functionalized EVA (EVASH), in combination with styrene‐butadiene block copolymer (SBS), was used to compatibilize the blends of polystyrene (PS) and ethylene–vinyl acetate copolymer (EVA). The reactive compatibilization was confirmed by the presence of insoluble material and from dynamic‐mechanical analysis. In addition to a more uniform morphology with small phase size, the compatibilization also provided excellent stabilization of the morphology, with an almost complete suppression of coarsening during annealing. As a consequence, a substantial increase on the elongation at break without significant influence on ultimate tensile strength was achieved for compatibilized blends with different compositions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 14–22, 2006     

Compatibilization of polypropylene/polystyrene blends with poly(styrene-b-butadiene-b-styrene) block copolymer

The compatibilizing effect of the triblock copolymer poly(styrene-b-butadiene-b-styrene) (SBS) on the morphology and mechanical properties of immiscible polypropylene/polystyrene (PP/PS) blends were studied. Blends with three different weight ratios of PP and PS were prepared and three different concentrations of SBS were used for investigations of its compatibilizing effects. Scanning electron microscopy (SEM) showed that SBS reduced the diameter of the PS-dispersed particles as well as improved the adhesion between the matrix and the dispersed phase. Transmission electron microscopy (TEM) revealed that in the PP matrix dispersed particles were complex “honeycomblike” aggregates of PS particles enveloped and joined together with the SBS compatibilizer. Wide-angle X-ray diffraction (WAXD) analysis showed that the degree of crystallinity of PP/PS/SBS slightly exceeded the values given by the addition rule. At the same time, addition of SBS to pure PP and to PP/PS blends changed the orientation parameters A₁₁₀ and C significantly, indicating an obvious SBS influence on the crystallization process in the PP matrix. SBS interactions with PP and PS influenced the mechanical properties of the compatibilized PP/PS/SBS blends. Addition of SBS decreased the yield stress and the Young's modulus and improved the elongation at yield as well as the notched impact strength in comparison to the binary PP/PS blends. Some theoretical models for the determination of the Young's modulus of binary PP/PS blends were used for comparison with the experimental results. The experimental line was closest to the series model line. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 2625–2639, 1998     

Compatibilization and characterization of blends of styrene–maleic anhydride copolymer with modified polyethylenes

Potentially reactive blends of styrene–maleic anhydride (SMAH) with ethylene/methyl acrylate/glycidyl methacrylate (E‐MA‐GMA) and nonreactive blends of SMAH with ethylene/methyl acrylate (E‐MA) were produced in a Brabender batch mixer and in a corotating twin‐screw extruder. The products were characterized in terms of rheology, morphology, and mechanical properties to understand the reaction characteristics between anhydride/epoxy functional groups. Storage modulus, G′, loss modulus, G″ and complex viscosity, η* of the reactive blends were higher than those of nonreactive ones. At 25% E‐MA‐GMA content, maximum in η* was obtained for the reactive blends. The reactive blends showed finer morphology than the nonreactive ones at all concentrations studied. Mechanical characterization showed that reactive SMAH/E‐MA‐GMA blends had higher tensile strength, % strain at break, and tensile modulus than the nonreactive blends for all corresponding modified polyethylene contents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 790–797, 2001     

Reactive compatibilization of poly(butylene terephthalate)/low‐density polyethylene and poly(butylene terephthalate)/ethylene propylene diene rubber blends with a bismaleimide

The reactive compatibilization effect of a small molecule, bismaleimide (BMI), on poly(butylene terephthalate) (PBT)/low‐density polyethylene (LDPE) and PBT/ethylene propylene diene (EPDM) rubber blends were investigated. All the blends were prepared by melt blending in the mixing chamber of a Haake Rheocord. The particle size of dispersed phase was reduced by >ten times by adding 1.2 wt % of BMI as observed with scanning electron microscopy. The torque‐time curve recorded during mixing showed that the addition of BMI leads to a significant increase in the viscosity of PBT, LDPE, EPDM, and the blends. This indicates that a chemical reaction has taken place. It was confirmed that free radicals are involved in the reactions because the addition of a stabilizer to the blends has removed all the compatibilizing effect, and the torque‐time curve does not show any increase in viscosity. A possible mechanism of compatibilization is proposed. The shear forces during melt mixing cause the rupture of chemical bond in the polymers, which form macroradicals of PBT, LDPE, or EPDM. These macroradicals react with BMI to form PBT‐BMI‐LDPE or PBT‐BMI‐EPDM copolymers. These in situ‐formed copolymers act as compatibilizers to give a significant refinement of the blend morphology. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2049–2057, 1999     

Mechanical properties of blends of polycarbonate with unmodified and maleic anhydride grafted ABS

Blends of polycarbonate/acrylonitrile–butadiene–styrene terpolymer (PC/ABS) and polycarbonate/maleic anhydride grafted ABS (PC/MABS) were prepared over the whole range of compositions using a single-screw extruder. Tensile, flexural, notched Izod impact properties, and the heat deflection temperature of these blends were determined. Mechanical properties of PC/MABS blends are nearly equal to or higher than, those predicted by the rule of mixtures, whilst those of PC/ABS blends show nearly equal, or negative deviation, from the rule of mixtures. The notched impact strength of PC/MABS blends shows a positive blending effect and proportionate increase from 25wt% PC to 75wt% PC. Scanning electron micrographs were taken of etched surfaces of selective blends. © 1998 SCI.     

Blends of aliphatic polyesters. IV. Morphology,swelling behavior,and surface and bulk properties of blends from hydrophobic poly(L-lactide) and hydrophilic poly(vinyl alcohol)

Blend films were prepared from hydrophobic poly(L -lactide) (PLLA) and hydrophilic poly(vinyl alcohol) (PVA) with different PLLA contents [X_PLLA (w/w) = PLLA/(PVA + PLLA)] by solution casting and melt quenching. Their morphology, swelling behavior, and surface and bulk properties were investigated. Polarizing optical microscopy, scanning electron microscopy, differential scanning calorimetry, X-ray diffractometry, and tensile testing revealed that PLLA and PVA were phase separated in these blend films and the PLLA-rich and PVA-rich phases both formed a continuous domain in the blend film of X_PLLA = 0.5. The water absorption of the blend films was higher for the blend films of low X_PLLA values when compared at the same immersion time, and it was larger than expected from those of nonblended PLLA and PVA films. The dynamic contact angles of the blend films were linearly increased with an increase in X_PLLA. The tensile strength and Young's modulus of the dry blend films decreased with a rise in X_PLLA, but this dependence was reversed because of the large decreases in tensile strength and Young's modulus for the blend films having high X_PLLA values after immersion in water. The elongation at break was higher for the wet blend film than for the dry blend film when compared at the same X_PLLA and that of the dry and wet blend films decreased with an increase in X_PLLA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2151–2160, 2001     

Reactive compatibilization of poly(l‐lactic acid)/poly(propylene carbonate) blends: Thermal,thermomechanical, and morphological properties

Poly(l ‐lactic acid) (PLLA) was blended with poly(propylene carbonate) (PPC) with various compositions by a melt‐blending process to evaluate their general properties for a potential flexible packaging field. The mechanical properties, including the tensile strength and modulus, revealed a tendency to decrease with the addition of ductile PPC; this was induced by the poor interfacial adhesion between PLLA and PPC with the cavities and clear edges and was observed through morphological observation. Reactive compatibilization was applied to improve the interfacial adhesion between PLLA and PPC, and the elongation at break was profoundly enhanced because of the improved interfacial adhesion between the two phases. The compatibilized PLLA/PPC blends showed considerable improvements in the storage modulus in the transition region with stable thermal stability; this could be a benefit for thermal processing. The addition of PPC had a great effect on the solidlike behavior and increased the elasticity of the PLLA/PPC blends. Up to 2.0 phr maleic anhydride showed a great efficiency in enhancing the dynamic storage modulus and complex viscosity of the PLLA/PPC blends. We also confirmed that it was feasible to fabricate PLLA/PPC blends with controllable barrier properties with combination of PLLA and PPC under reactive compatibilization while retaining the biodegradability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43388.