Styrene maleic anhydride and styrene glycidyl methacrylate copolymers as in situ reactive compatibilizers of polystyrene/nylon 6,6 blends

The reactive type copolymers styrene maleic, anhydride (SMA) and styrene glycidyl methacrylate (SG) are used as in situ compatibilizers in polyblends of polystyrene (PS) and nylon 6, 6 (N66). Both copolymers can react with N66 to form copolymers as effective compatibilizers to reduce interfacial tension and increase phase adhesion. However, the toughness of the compatibilized blends is significantly lower than of the corresponding noncompatibilized blends. Only a small fraction of SMA is actually reacted in a typical melt blending, and SG copolymer seems to be more reactive than SMA. The unreacted copolymers are expected to be distributed mostly in the PS phase because of their structural similarity. The reacted copolymers are not exclusively distributed along the interface; some may distribute in both matrices. SMA is known as a very brittle polymer, and the way it is distributed can greatly influence the toughness of the resulting blends. PS is also very brittle relative to N66, and moreover a high amount of SMA in the N66 phase is detrimental since N66 is responsible for the toughness of PS/N66 blends. The better compatibilized blends have the tendency to bring more SMA and reacted SMA into the N66 phase. The relative detrimental effect on the inherent toughness of N66 is much more severe than in case of PS, if they contain the same amount of SMA. This study demonstrates that polyblends with good compatibilizers do not guarantee toughness improvement. The way the compatibilizers affect the inherent properties of the matrix needs also to be taken into consideration.     

Poly(styrene-graft-ethylene oxide) as a compatibilizer in polystyrene/polyamide blends

Polystyrene (PS) blends containing a dispersed phase of either polyamide-6 (PA-6) or polyamide-12 (PA-12) were compatibilized by additions of 1, 3, or 5 wt % poly(styrene-graft-ethylene oxide). The graft copolymers were found to have a stabilizing effect on the domain sizes. Weight average radii of PA-6 domains in compression molded samples were reduced by a factor of 5 with 3 wt % graft copolymer added. The corresponding size reduction for PA-12 domains was by a factor of 3. Also, the domain sizes were more uniformly distributed in blends containing the graft copolymers. Thermal analysis of the blends revealed that compatibilization retarded the PA crystallization, with some PA crystallizing at the PS glass transition. This retarded crystallization is explained as a result of the domain size reduction and by the presence of graft copolymer at the interface. The graft copolymers had a toughening effect on the blends and the impact strength of a PS/PA-12 blend was improved by 65% by adding 3 wt % of graft copolymer. Binary blends of the PA and poly(ethylene oxide) (PEO) were investigated in a separate study to verify miscibility of the graft copolymer side chains and the PA. Hydrogen bonding between PA-6 and PEO was confirmed by IR spectroscopy and partial miscibility was indicated by melting point depressions. © 1995 John Wiley & Sons, Inc.     

Characterization of nylon 6/ABS blends with and without a maleated polybutadiene as compatibilizer

The physical properties of nylon 6/poly(acrylonitrile-butadiene-styrene) terpolymer (ABS) blends using a maleated polybutadiene (denoted PB-g-MA) as compatibilizer were investigated. The morphology results reveal that ABS domain sizes decrease with an increasing compatibilizer content, suggesting the good interaction between the nylon 6 matrix and the ABS dispersed phase. Cooling conditions and compatibilizer contents strongly affect the crystalline structure of nylon 6, as determined from X-ray diffraction and non-isothermal crystallization thermal analyses. The coexistence of α- and predominantly γ-form crystals for the 10 phr compatibilized blends was observed. Isothermal crystallization kinetics suggests that the introduced compatibilizer impeded the growth rate of the crystals, especially for the higher compatibilizer content. The compatibilizer was beneficial in enhancing the thermal stability of the blends.     

Alteration of the mechanical and thermal properties of nylon 6/nylon 6,6 blends by nanoclay

Nylon 6 [N(6)], nylon 6,6 [N(6,6)], and their blends at different clay loadings were prepared. The mix was melted and injected into strip‐shaped samples. Mechanical and thermal analyses were performed to investigate the effect of blending and the incorporated clay on the mechanical and thermal properties. Enhancements in the Young's modulus and hardness were obtained for all of the nanocomposites, with a 55% increase in Young's modulus after the addition of 6 wt % nanoclay, although the improvement in tensile strength depended on the blend ratio, with greatest effects on the 50% N(6)/50% N(6,6) blend with increases of 44 and 59% for 2 and 4% clay loadings, respectively. Thermogravimetric analysis showed an enhancement in the thermal properties in the 50% N(6)/50% N(6,6) blend at 2% clay loading, and the blend exhibited ductile behavior at this loading. Increases in the crystallization peak temperatures of 10–15° in N(6,6) and the two blends 30% N(6)/70% N(6,6) and 50% N(6)/50% N(6,6) were observed after the addition of the clay. The nanoclay enhanced the γ‐/β‐form crystals in N(6) and N(6,6) neat polymers and also in the blends. Fourier transform infrared spectroscopy FT‐IR revealed the formation of hydrogen bonding and the possible formation of ionic bonds between the polymers and the nanoclay, which resulted in enhancements in the mechanical properties of the blends. The distribution of the nanoclay in the blend was well dispersed, as shown by X‐ray diffraction analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Supercritical CO2-assisted synthesis of poly(acrylic acid)/nylon6 and polystyrene/nylon6 blends

Poly(acrylic acid)/nylon6 and polystyrene/nylon6 blends were prepared using supercritical CO₂ as substrate-swelling agent and monomer/initiator carrier. Both supercritical CO₂/nylon6 binary system and SC CO₂/monomer/nylon6 ternary system were studied. Virgin nylon6 and synthesized blends were characterized through differential scanning calorimetry, infrared spectroscopy, and polarizing microscopy. Supercritical CO₂-induced crystallization was found in modified nylon6.     

Grafted syndiotactic polystyrene synthesized via melting graft copolymerization used as a compatibilizer for immiscible syndiotactic polystyrene/polyadimide 66 blends

A new grafted syndiotactic polystyrene (g‐sPS), to be used as a compatibilizer for syndiotactic polystyrene (sPS)/polyadimide 66 blends, was prepared by the melting graft copolymerization of sPS and monomers composed of itaconic acid and dibutyl maleate with dicumyl peroxide as an initiator. The resulting g‐sPS possessed a side‐chain structure identified by IR spectra, and the results of mechanical testing show that a good impact strength and tensile strength were obtained for g‐sPS at a 7.16‐phr addition of monomer with a 3:1 proportion of dibutyl maleate and itaconic acid. Differential scanning calorimetry and scanning electron microscopy analysis indicated that the g‐sPS maintained a high glass‐transition temperature and a crystalline structure. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1659–1666, 2005     

Alternating copolymers as compatibilizer for blends of poly(ethylene terephthalate) and polystyrene

Compatibilization of blends of poly(ethylene terephthalate) (PET) and polystyrene with alternating copolymers of maleic anhydride and isobutylene (IM) and its partly phenol substituted product (PIM) has been studied. The characterization techniques applied were dynamic mechanical analysis, differential scanning calorimetry, scanning electron microscopy, and tensile testing. In all compositions studied, morphological observations demonstrated that the addition of approximately 5 wt % of copolymers led to the domain size reduction of dispersants. The PIM copolymer was most effective in reducing the domain size, whereas the IM copolymer was less satisfactory. The blends containing PIM also gave the more enhanced ultimate strength than those of other systems. The noncrystalline PIM copolymers lowered the tensile modulus of the blend as much as 60% even in the polystyrene‐rich region and varied linearly with values of quenched PET modulus throughout the compositions, indicating the formation of homogeneous amorphous phase. Based on the experimental observation that the reduced domain size with PIM copolymer, a compatibilization mechanism of the blend with PIM alternating copolymer is proposed and discussed in terms of the interactions between ester groups of PET and PIM (transesterification), and the possible formation of intermediate π‐complex between the π‐electron deficient aromatic ring of PIM and π‐electron rich aromatic ring of PS. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1998–2007, 2000     

Carboxylation of polypropylene by reactive extrusion with functionalized peroxides for use as a compatibilizer in polypropylene/polyamide-6,6 blends

Variable quantities of functionalized peroxides bearing carboxylic acid groups were reacted with polypropylene (PP) in a twin-screw extruder. Systematic variations in the molecular structure of the peroxides were found to significantly affect the grafting efficiency of the carboxylic acid group onto the PP backbone, as well as affect the polymer degradation process. This behavior was attributed to the relative reactivities of the different free radicals generated by thermal decomposition of the peroxides. Furthermore, the functionalized polypropylene (f-PP) was investigated as a compatibilizing additive for 80/20 PP/PA-6,6 (polyamide 6,6) blends. With incorporation of the f-PP into the blends, differential scanning calorimetry (DSC) showed an 80°C decrease in the PA-6,6 crystallization temperature. A near linear increase in the impact strength of the blends was observed with f-PP incorporations up to 30% of the PP phase. Moreover, blends containing 30% f-PP demostrated impact properties approaching that of pure PA-6,6.     

Phase morphology development and melt rheological behavior in nylon 6/polystyrene blends

Phase morphology development in immiscible blends of polystyrene (PS)/nylon 6 was investigated. The blends were prepared by melt blending in a twin‐screw extruder. The influence of the blend ratio, rotation speed of the rotors, and time of mixing on the phase morphology of the blends was carefully analyzed. The morphology of the samples was examined under a scanning electron microscope (SEM) and the SEM micrographs were quantitatively analyzed for domain‐size measurements. From the morphology studies, it is evident that the minor component, whether PS or nylon, forms the dispersed phase, whereas the major component forms the continuous phase. The 50/50 PS/nylon blend exhibits cocontinuous morphology. The continuity of the dispersed phase was estimated quantitatively based on the preferential solvent‐extraction technique, which suggested that both phases are almost continuous at a 50/50 blend composition. The effect of the rotor speed on the blend morphology was investigated. It was observed that the most significant breakdown occurred at an increasing rotor speed from 9 to 20 rpm and, thereafter, the domain size remained almost the same even when the rotor speed was increased. The studies on the influence of the mixing time on the blend morphology indicated that the major breakdown of the dispersed phase occurred at the early stages of mixing. The melt rheological behavior of the blend system was studied using a capillary rheometer. The effect of the blend ratio and the shear stress on the melt viscosity of the system was investigated. Melt viscosity decreased with increase in the shear stress, indicating pseudoplastic behavior. With increase of the weight fraction of PS, the melt viscosity of the system decreased. The negative deviation of the measured viscosity from the additivity rule indicated the immiscibility of the blends. The domain size versus the viscosity ratio showed a minimum value when the viscosities of the two phases were matched, in agreement with Wu's prediction. The morphology of the extrudates was analyzed by SEM. From these observations, it was noted that as the shear rate increased the particle size decreased considerably. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3537–3555, 2002     

Characteristics of nylon 6,6/nylon 6,6 grafted multi-walled carbon nanotube composites fabricated by reactive extrusion

Nylon 6,6 composites containing nylon 6,6 grafted multi-walled carbon nanotubes (nylon 6,6-g-MWCNT) were fabricated from nylon 6,6 and acyl chloride grafted MWCNT (MWCNT–COCl) by reactive extrusion. MWCNT–COCl was produced by reacting acid-treated MWCNTs with thionyl chloride. Formation of nylon 6,6-g-MWCNT by reactive extrusion was confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and scanning electron microscopy. To quantify the interfacial adhesion energies of nylon 6,6 and pristine and functionalized MWCNTs, the contact angles of cylindrical drop-on-fiber systems were determined using the generalized droplet shape analysis. The interfacial adhesion energy of the nylon 6,6/nylon 6,6-g-MWCNT composite was twice that of the nylon 6,6/pristine MWCNT composite. Nylon 6,6-g-MWCNTs exhibited excellent dispersion in the composite, whereas pristine MWCNTs exhibited poor dispersion when composite films were prepared by solvent casting. The reinforcement level of the composite increased with increasing MWCNT content. Among the composites examined, the nylon 6,6/nylon-g-MWCNT composite with a fixed MWCNT content exhibited the highest level of reinforcement.     

Microstructural investigations of PBT/nylon 6,6 composites

The microstructure of composites made from blends of poly(p-phenylene benzobisthiazole) [PBT] and nylon 6,6 has been investigated with wide-angle X-ray diffraction, selected area electron diffraction, and small-angle X-ray scattering techniques. The composite samples investigated were spun in both fiber and film forms dilute solutions of methane sulfonic acid. The structure of the composites was found to be a microfibrillar network of PBT in a matrix of partially crystalline nylon 6,6. The diameters of the PBT microfibrils were in the range of 30 to 70 Å.     

Synergistic effects of silica nanoparticles and reactive compatibilizer on the compatibilization of polystyrene/polyamide 6 blends

This study examines the selective dispersion of nano‐SiO₂ in polystyrene (PS) and polyamide 6 (PA6) blends. With the coupling assistance of 3‐methacryloylpropyl trimethoxysilane (MPS), nano‐SiO₂ surfaces are grafted with PS chains of different molecular weights (SiO₂–MPS–PS) or reactive random copolymer of styrene (St) and 3‐isopropenyl‐α,α′‐dimethylbenzene isocyanate (TMI) to produce SiO₂–MPS–P(St–co–TMI). The isocyanate groups of the reactive copolymer can react with the terminal group of the PA6 to form a graft copolymer, which helps in controlling the location of nano‐SiO₂ between the PS and PA6 phases. Field‐emission scanning electron microscopy imaging combined with the rheological method was used to investigate the location and dispersion of nano‐SiO₂, as well as the morphology of the PS/PA6 blends, at low nano‐SiO₂ loading. Compared with pristine SiO₂, the modified SiO₂ with different chain lengths adjusted the PA6 phase with refined size and narrow size distribution because of the strong interaction with both phases. The SiO₂–MPS–PS with appropriate length is the most effective. The use of nano‐SiO₂ along with the reactive compatibilizer provides synergistic effects for improving the compatibilization of PS/PA6 blends. POLYM. ENG. SCI., 57:1301–1310, 2017. © 2017 Society of Plastics Engineers     

Interaction characterization of PA1010/PP blends using PP-g-AA as compatibilizer

The morphology of polyamide 1010/polypropylene blends was found to significantly depend upon the concentration of the compatibilizer[polypropylene-grafted-acrylic acid (PP-g-AA)]. A significant reduction in phase size was observed because of the interaction that existed between the PP-g-AA and polyamide. These interactions have been confirmed by several methods. The tensile mechanical properties and impact behavior of the prepared blends were investigated and correlated with scanning electron microscope (SEM) analysis of the fracture surfaces. It was found that PP-g-AA as the compatibilizer has a profound effect upon the properties of the blends. This behavior is attributed to a series of chemical and physico-chemical interactions taking place between the two components.     

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     

丁腈橡胶增容丁苯橡胶/聚氯乙烯共混体系

采用一系列结合丙烯腈质量分数不同的丁腈橡胶(NBR)作为丁苯橡胶(SBR)／聚氯乙烯(PVC)不相容共混物的增容剂,研究了SBR／PVC／NBR硫化胶的力学性能,并用扫描电子显微镜、傅里叶变换红外光谱仪和动态黏弹仪研究了该硫化胶的形态结构与相容性。结果表明,结合丙烯腈质量分数为20％～26％的NBR是SBR／PVC的优良增容剂,可提高共混物的力学性能,使SBR相和PVC相达到微细均匀化分散,并在两相之间形成了界面层,使得增容效果达到最佳。     

A study on PVC/LLDPE blends with solid-state-chlorinated polyethylene as compatibilizer

Chlorinated polyethylene (CPE) prepared by solid-state chlorination was used as compatibilizer for poly(vinyl chloride) (PVC)/linear low-density polyethylene (LLDPE) blends. Effects of CPE molecular structure on stress-strain behaviors, dynamic mechanical properties, and morphologies of PVC/LLDPE blends were studied by using SEM, TEM, DMA, and testing mechanical properties. The results showed that the compatibility of PVC/LLDPE blends was improved with the addition of CPE. Also, adhesion strength between the two phases and mechanical properties of the blends were increased. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2535–2541, 1997     

Syndiotactic polystyrene‐b‐atactic polypropylene block copolymer alloy as a compatibilizer for syndiotactic polystyrene/isotactic polypropylene blends

A polymeric alloy (SP–A) containing syndiotactic polystyrene (sPS), atactic polypropylene (aPP), and about 66 wt % sPS‐b‐aPP diblock copolymer, was prepared by the sequential feed of monomers in the presence of the half‐titanocene Cp*Ti(OBz)₃ (where Cp* is C₅Me₅ and Bz is PhCH₂), modified methylaluminoxane, and external triisobutylaluminum. The effects of the SP–A alloy as a compatibilizer for sPS and isotactic polypropylene (iPP) blends were evaluated. The blending of sPS and iPP, with and without SP–A, was performed in a single‐screw miniextruder with a side channel that allowed the continuous recycling of materials. The influence of SP–A on the mechanical and thermal properties of the immiscible sPS/iPP blends was investigated over a range of composition. The presence of the SP–A alloy resulted in a significant improvement of the impact strength of the blends compared with that of pure sPS and their pure blends. This improvement was particularly obvious in the sPS/iPP (90/10 wt %) blend containing 5 wt % SP–A. Morphological analysis of the impact‐fractured surface of the ternary blends indicated that the sPS‐b‐aPP diblock copolymer contained in the SP–A alloy acted as an efficient compatibilizer by decreasing the dispersed‐phase iPP particle size, improving the interfacial adhesion, and generating a stable microphase‐separated state. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1596–1605, 2003     

Enhancing compatibilizer function by controlled distribution in hydrophobic polylactic acid/hydrophilic starch blends

Various polylactic acid (PLA)/cornstarch blends, with and without the compatibilizer methylenediphenyl diisocyanate (MDI), were prepared by melt processing using a twin‐screw extruder. In the blends where it was included, MDI was distributed in either the PLA or starch phase through controlling processes conditions. The effects of MDI inclusion and its distribution on the resultant microstructures, mechanical properties, and thermal and rheological behaviors of the blends were studied via scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, mechanical testing, and Haake rheometer. The results showed that when the MDI was distributed in the starch phase before blending with PLA, the highly reactive isocyanate groups in the MDI were most probably consumed by water, resulting in an overall weakening of its compatibilizing effect. However, when the MDI was distributed in the PLA phase before blending with starch, modulus, yield strength, and impact strength were all increased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Processing-morphology-property relationships in polyethylene/acrylonitrile copolymer/compatibilizer blends

Effects of blend composition, compatibilizer, and processing conditions on the morphology, rheology, and mechanical properties of the ternary blends are investigated. Introduction of compatibilizer and increasing shear rate lead to a finer particle dispersion. A modification of Wu's equation is utilized to obtain an estimate of the interfacial tension. The results indicate a reduction in interfacial tension upon addition of compatibilizer. Morphological stability of these blends is studied by reprocessing them in an injection molding machine and a twin-screw extruder. The nature of the reprocessing history was found to govern the morphology and the mechanical properties of the blends investigated.     

Tensile yield in nylon 6,6

Uniaxial tension tests to, the yield point were performed on poly(hexamethylene adipamide) (nylon 6,6) as a function of temperature from 21 to 200°C at a strain rate of 2 min^?1. At 21 and 60°C, measurements were also made at strain rates from 0.02 to 8 min^?1. Using simple rate theory, reasonable values of activation volume were obtained, but the simple theory is inadequate to determine the activation energy. The yield-strain temperature dependence changes at 160°C as a result of a reversible crystal-crystal transition. Because of this behavior of the yield strain, the yield energy is not a linear function of temperature, as observed for several other polymers.