增容聚丙烯/聚苯乙烯共混物的相形态

综述了作为增容剂的接枝共聚物与嵌段共聚物,反应增容,其他技术增容以及共混条件对聚丙烯／聚苯乙烯(PP,PS)共混物的相形态研究进展。PP／PS共混物通过增容可以改善共混物相形态和提高界面粘结,这为提高PP／PS共混物的物理与力学性能提供了依据。     

Effect of the molecular architecture of graft copolymers on the phase morphology and tensile properties of PS/EVA blends

Graft copolymers of poly(ethylene‐co‐vinyl acetate) (EVA) grafted with polystyrene (PS) with different molecular weight and different EVA/PS ratio were prepared by coupling reaction between acyl chloride functionalized PS (PS‐COCl) and hydrolyzed EVA. PS‐COCl with controlled molecular weight was prepared by anionic polymerization of styrene, followed by end capping with phosgene. The effect of the molecular architecture of the graft copolymer on the compatibilization of PS/EVA blends was investigated. Substantial improvement in the elongation at break and ductility was observed using the graft copolymer with PS segments with molecular weight as high as 66,000 g/mol and with a PS proportion equal or higher than EVA. The effect of the compatibilization on the morphology was also investigated by scanning electron microscopy and atomic force microscopy. The blend that presented the highest value of elongation at break also displayed dispersed phase constituted by inclusions of the PS phase inside the EVA particle forming a cocontinuous structure, as observed by AFM. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Physical properties of model graft copolymers and their use as blend compatibilizers

The present investigation pertains to the structure–property relationships of highly structured graft copolymers. The specific model graft copolymers are based on an elastomeric backbone, i.e., poly(ethyl acrylate), and monodisperse thermoplastic grafts, i.e., polystyrene. The synthesis of these graft copolymers is based on the free-radical polymerization of ethyl acrylate and an anionically polymerized polystyrene macromonomer. It is clearly demonstrated that grafts significantly enhance tensile properties. The level of improvement is directly related to the graft level, i.e., number of grafts/chain, and graft molecular weight. In addition, blending these graft copolymers into their respective homopolymer mixture results in a mechanical performance strikingly dependent on the molecular characteristics of the graft copolymer. For example, tensile strength is maximized at a level between one and two grafts per chain. This result parallels observations noted in blend compatibilization using diblock and triblock copolymers. It is also demonstrated that using mutually grafted copolymers produces an interesting variety of compatibilized ternary (or higher) component blends. © 1994 John Wiley & Sons, Inc.     

Effect of the molecular structure of ethene–propene and styrene–butadiene copolymers on their compatibilization efficiency in low‐density polyethylene/polystyrene blends

The effect of the molecular structure of styrene–butadiene (SB) block copolymers and ethene–propene (EPM) random copolymers on the morphology and tensile impact strength of low‐density polyethylene (LDPE)/polystyrene (PS) (75/25) blends has been studied. The molecular characteristics of SB block copolymers markedly influence their distribution in LDPE/PS blends. In all cases, an SB copolymer is present not only at the interface but also in the bulk phases; this depends on its molecular structure. In blends compatibilized with diblock copolymers, compartmentalized PS particles can also be observed. The highest toughness values have been achieved for blends compatibilized with triblock SB copolymers. A study of the compatibilization efficiency of SB copolymers with the same number of blocks has shown that copolymers with shorter PS blocks are more efficient. A comparison of the obtained results with previous results indicates that the compatibilization efficiency of a copolymer strongly depends both on the blend composition and on the properties of the components. The compatibilization efficiency of an EPM/SB mixture is markedly affected by the rheological properties of the copolymers. The addition of an EPM/SB mixture containing EPM with a higher viscosity leads to a higher improvement or at least the same improvement in the tensile impact strength of a compatibilized blend as the same amount of neat SB. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of epoxy-chain end(s) functional macromonomer of polystyrene and its use in photoinitiated cationic polymerization

A novel epoxy chain-end(s) functional polystyrene macromonomer (PSt-CHO) was prepared via free radical polymerization (FRP) of styrene (St) initiated by 4,4′-azobis(3-cyclohexenylmethyl-4-cyanopentanoate) (ACCP) azo initiator and epoxidation on workup with 3-chloroperoxybenzoic acid under inert atmosphere in methylene chloride at 0 °C. 4,4′-Azobis(4-cyanopentanoyl chloride) (ACPC) was obtained by the reaction of 4,4′-azobis(4-cyanopentanoic acid) (ACPA) with phosphorus pentachloride in methylene chloride. The ACCP was synthesized by the condensation reaction of 3-cyclohexene-1-methanol with ACPC. The FRP of styrene with ACCP has yielded polystyrene with cyclohexene end(s) group (PSt-CH). Epoxidation of the PSt-CH was performed using 3-chloroperoxybenzoic acid to obtain epoxy chain-end(s) functional polystyrene macromonomer (PSt-CHO). This macromonomer was used as precursor in photoinitiated cationic polymerization for obtaining brush-type and graft copolymers. Photoinitiated cationic homopolymerization of the macromonomer in the presence of diphenyliodonium salt at λ = 300 nm yielded brush-type polymers. Photoinitiated cationic copolymerization of the macromonomer with cyclohexene oxide (CHO) monomer and diphenyliodonium salt at λ = 350 nm produced graft copolymers. The polymers synthesized were characterized by means of FTIR, ¹HNMR and gel permeation chromatography measurements. All the spectroscopic studies revealed that a macromonomer of polystyrene with cyclohexene oxide (CHO) functionality at the chain end(s) (PSt-CHO) and their brush-type and graft copolymers were obtained.     

Compatibilization efficiency of styrene‐butadiene block copolymers as a function of their block number

Effect of block number in linear styrene‐butadiene (SB) block copolymers (BCs) on their compatibilization efficiency in blending polystyrene (PS) with polybutadiene (PB) was studied. Di‐, tri‐, or pentablocks of SB copolymers as well as their combinations were blended with the mentioned homopolymers; supramolecular structure determined by small angle X‐ray scattering method (SAXS), morphology using scanning electron microscopy (SEM) combined with image analysis (IA), and stress transfer characteristics of the blends were chosen as criteria of compatibilization efficiency of the copolymers used. It was proved that the addition of SB BCs led to remarkably finer phase structure and substantially higher toughness of PS/PB blends. Triblock copolymer showed to be the compatibilizer with higher efficiency than diblock, pentablock, and the di/triblock copolymer mixture. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymer blends of poly(ethylene‐2,6‐naphthalate) with polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers. I. Rheology,morphology, and mechanical properties

The compatibilization of blends of poly(ethylene‐2,6‐naphthalate) (PEN) with polystyrene (PS), through the styrene‐glycidyl methacrylate copolymers (SG) containing various glycidyl methacrylate (GMA) contents, was investigated in this study. SG copolymers are able to react with PEN terminal groups during melt blending, resulting in the formation of desirable SG‐g‐PEN copolymers in the blend. These in situ formed copolymers tend to reside along the interface preferentially as the result of interfacial reaction and thus function as effective compatibilizers in PEN/PS blends. The compatibilized blends exhibit higher viscosity, finer phase domain, and improved mechanical properties. It is found that the degree of grafting of the in situ formed SG‐g‐PEN copolymer has to be considered as well. In blends compatibilized with the SG copolymer containing higher GMA content, heavily grafted copolymers would be produced. The length of the styrene segment in these heavily grafted copolymers would be too short to penetrate deep enough into the PS phase to form effective entanglements, resulting in the lower compatibilization efficiency in PEN/PS blends. Consequently, the in situ formation of SG‐g‐PEN copolymers with an optimal degree of grafting is the key to achieving the best performance for the eventually produced PEN/PS blends through SG copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 967–975, 2003     

Compatibilization efficiency of styrene–butadiene triblock copolymers in polystyrene–polypropylene blends with varying compositions

The compatibilization efficiency of two styrene‐butadiene‐styrene triblock copolymers with short (SB1) and long (SB2) styrene blocks was studied in polystyrene (PS)–polypropylene (PP) blends of composition 20, 50, and 80 wt % PS. The supramolecular structure of the blends was determined by small‐angle X‐ray scattering, and the morphology was studied with transmission electron microscopy and scanning electron microscopy. Structural changes in both the uncompatibilized and compatibilized blends were correlated with the values of tensile impact strength of these blends. Even though the compatibilization mechanisms were different in blends with SB1 and SB2, the addition of the block copolymers to the PS–PP 4/1 and PS–PP 1/4 blends led to similar structures and improved the mechanical properties in the same way. These block copolymers had a very slight effect on the impact strength in PS–PP 1/1 blends, exhibiting a nearly cocontinuous phase morphology. The strong migration of SB2 copolymers to the interface and of SB1 copolymers away from the interface were detected during the annealing of compatibilized PS–PP 4/1 blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2431–2441, 2004     

Highly active novel Ni-diimine pre-catalyst containing bis-ketimine ligand for the vinyl polymerization of norbornene

Novel Nickel-diimine pre-catalyst (1NiBr₂) containing N,N′-bis(diphenylmethylene)-ethylenediamine ligand was able to quantitatively polymerize norbornene (NBE) into polynorbornene (PNBE) at 50 °C upon activation with methylaluminoxane (MAO). The monomer concentration governs the rate of reaction and the polymer characteristics. Thermal and spectral analysis revealed the polymerization pathway to occur via vinyl addition and not ring opening. The homopolymerization of 1-hexene or ethylene could not be achieved using 1NiBr₂/MAO catalyst system, but the presence of 1-hexene did not prevent the quantitative polymerization of NBE without 1-hexene incorporation. The characteristics of the polymers formed were found to be different in terms of solubility and molecular weight compared to those of the product generated by the homopolymerization of NBE in the absence of 1-hexene. Here 1-hexene acted as a chain transferring agent and control the molecular weight of PNBEs produced.     

Synthesis, characterization and micelle formation of amphiphilic graft copolymers

The macromonomer method is a useful tool for the preparation of various graft copolymers with well-defined structure and composition. Macromonomers were prepared by anionic polymerization of styrene followed by a direct coupling reaction of polystyryllithium with an excess of vinylbenzyl chloride. The control of the terminal functional groups is particularly important to ensure the reactivity of macromonomers in the radical copolymerization; the degree of functionality was determined by both n.m.r. and u.v.-vis. spectroscopy to be from 85–99%. Graft copolymers were synthesized by radical copolymerization of (vinylbenzyl) polystyrene macromonomer with 2-hydroxyethyl methacrylate (HEMA), or with acrylic acid. The organization ability of the copolymers to form micelles was investigated by ¹H n.m.r. spectroscopy, and verified by their ability to stabilize emulsions. These copolymers were found to be effective surfactants for emulsion polymerization of polystyrene latexes. © 1997 Elsevier Science Ltd.     

Polymer blends of poly(trimethylene terephthalate) and polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers

The compatibilizing effects of styrene‐glycidyl methacrylate (SG) copolymers with various glycidyl methyacrylate (GMA) contents on immiscible blends of poly(trimethylene terephthalate) (PTT) and polystyrene (PS) were investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and ¹³C‐solid‐state nuclear magnetic resonance (NMR) spectroscopy. The epoxy functional groups in the SG copolymer were able to react with the PTT end groups (? COOH or ? OH) to form SG‐g‐PTT copolymers during melt processing. These in situ–formed graft copolymers tended to reside along the interface to reduce the interfacial tension and to increase the interfacial adhesion. The compatibilized PTT/PS blend possessed a smaller phase domain, higher viscosity, and better tensile properties than did the corresponding uncompatibilized blend. For all compositions, about 5% GMA in SG copolymer was found to be the optimum content to produce the best compatibilization of the blend. This study demonstrated that SG copolymers can be used efficiently in compatibilizing polymer blends of PTT and PS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2247–2252, 2003     

Compatibilization of PS and PA6 Blends by Means of Poly(oxyalkylene)amine Modified Styrene-Maleic Anhydride Copolymer

The compatibilization effect of SMA-co-M2070-co-DAP comb-like copolymers, SMMD, on immiscible blends of polystyrene (PS) and polyamide-6 (PA6) is examined in terms of phase structure, thermal behavior, dynamic mechanical analysis, and mechanical properties. A series of SMMD copolymers are synthesized and confirmed by the FT-IR analysis. These compatibilizers have different amphiphilic properties depending on the content of hydrophilic poly(oxyethylene) segments (M2070) and the molar ratio of MA/amine. The morphologies of PS/PA6, affected by the increasing amount of SMMD compatibilizer, show a more regular and finer dispersion. The sizes of dispersed particles have no marked changes over the saturation level of compatibilizer. The glass transition temperatures of the blends are between that of PS and PA6, while the added SMMD copolymer is mainly located at the interface. Using these SMMD copolymers, the compatibilized blends show some improvements in mechanical properties, including Izod impact strength and flexural properties. The graft poly(oxyethylene) and amide functionalities in SMMD structures in forming hydrogen bonding with PA6 and, the polystyrene backbone in π–π interaction with PS facilitate the compatibilizing effect.     

Compatibilization of polystyrene/poly(dimethyl siloxane) solutions with star polymers containing a γ-cyclodextrin core and polystyrene arms

Solutions of polystyrene and poly(dimethyl siloxane) in chloroform are compatibilized by the addition of a small amount of a star polymer consisting of a γ-cyclodextrin core and polystyrene arms. Compatibilization is visually observed when turbid PDMS/PS emulsions become clear upon addition of the CD-star molecule. The mechanism of compatibilization involves threading of the CD-core by PDMS and solubilization of the resulting “slip-ring graft copolymer” via the PS star arms. This process breaks up the undissolved PDMS domains into smaller, more stable micelles. Evidence for threading of the CD-core by PDMS is found using ROESY 2D-NMR. Intrinsic viscosity measurements for the compatibilized solutions show behavior similar to conventional graft copolymers which form micelles in a selective solvent. Dynamic light scattering measurements suggest that the micelle size is approximately 20 nm. The effects of varying the PDMS molecular weight, PDMS concentration and CD-star concentration are studied.     

Reactive compatibilization of PE/PS blends. Effect of copolymer chain length on interfacial adhesion and mechanical behavior

This paper deals with in situ compatibilization of PE/PS blends via Friedel-Crafts reaction, performed at the interphase. Two polyethylenes having different molecular weights, and the same PS, were used along a wide range of catalyst concentration. The influence of the graft copolymer architecture and content on the efficiency of blend compatibilization was studied. The emulsifying effect, morphological aspects and mechanical behavior were also assessed for these blends. The amount of copolymer formed increases with catalyst concentration and the short chain length fraction of the homopolymers. The high molecular weight (MW) copolymers behaved as better compatibilizers as they showed, at the cmc, greater graft copolymer concentration than the low MW ones. A substantial increase in interfacial adhesion and particle size reduction was observed, even at catalyst concentrations as low as 0.3 wt%. In correspondence, mechanical properties, like ductility and yield strength, were enhanced by the effect of this Friedel-Crafts reaction's compatibilization.     

Polyethylene-polystyrene grafting reaction: effects of polyethylene molecular weight

Blending of different thermoplastic polymers usually results in segregated and low value materials for almost any mixing condition. Nevertheless, a synergetic combination of properties can be obtained by an adequate compatibilization via reactive blending. In this work a Friedel-Crafts alkylation reaction is used to graft polyethylene chains onto polystyrene. The relation between the initial PE molecular weight (MW) and the structure of the compatibilizer copolymer is studied by a combination of size exclusion chromatography and Fourier transform infrared spectroscopy. The amount of copolymer formed is estimated from the amount of polystyrene reacted. The relative lengths of the grafted polyethylene chains are assessed. It is found that lower MW PE produces, upon reaction, a greater amount of short chain length grafted PE onto PS than higher MW PE. The results are in agreement with theories relating the component MW to the reaction localization at the interface.The low cost Friedel-Crafts alkylation results in a convenient reaction for the in situ compatibilization of PE/PS blends. It produces enough graft copolymer to compatibilize the phases without causing PS crosslinking and PE chain scission.     

Poly(α-t-butoxy-ω-styrylo-glycidol): a new reactive surfactant

Summary Poly(α-t-butoxy-ω-styrylo-ethoxy ethyl glycidyl ether) was synthesized via the termination of the potassium t-butoxide initiated anionic polymerization of ethoxy ethyl glycidyl ether with p-chloromethylstyrene. The macromonomer was copolymerized with styrene. Subsequent hydrolysis of the copolymers leads to polystyrene - graft - polyglycidol. Poly(α-t-butoxy-ω-styrylo-glycidol), synthesized through the hydrolysis of the macromonomer so obtained, acts as reactive emulsifier (surfmer) in the emulsion copolymerization of styrene in water. Received: 13 January 1998/Revised version: 24 February 1998/Accepted: 5 March 1998     

Synthesis and characterization of cyclohexene oxide functional polystyrene macromonomers by ATRP and their use in photoinitiated cationic polymerization

In this study, a novel well-defined macromonomer of epoxy end-functionalized polystyrene was synthesized by atom transfer radical polymerization (ATRP). The compound 3-cyclohexenylmethyl-2-bromopropanoate was synthesized by the condensation of 3-cyclohexene-1-methanol with 2-bromopropanoyl bromide. Subsequently, the epoxidation of the obtained 3-cyclohexenylmethyl-2-bromopropanoate using 3-chloroperoxybenzoic acid results in a new epoxy functional ATRP initiator. The ATRP of styrene (St) in bulk at 110 °C, by means of this initiator in conjunction with the cuprous complex Cu(I)Br/bipyridine, yields a well-defined macromonomer of polystyrene with an epoxy end group. GPC, IR, and ¹H NMR analyses revealed that a low-polydispersity polystyrene with the desired functionality at the end of the chain was obtained. The photoinduced cationic polymerization of this macromonomer yielded graft and block copolymers.     

Reactivity of macromonomer in copolymerization of styrene with styrene-terminated macromonomer by CpTiCl3-MAO catalyst

Summary The copolymerization of styrene (St) and styrene-terminated macromonomers with CpTiCl₃-MAO catalyst was investigated. The contents of the macromonomer in the graft copolymer was found to depend on the miscibility of the macromonomer with the main chain polystyrene formed by copolymerization. miscible system of the syndiotactic polystyrene in the main chain and atactic polystyrene in the side chain was favorable for the incorporation of the macromonomer into the graft copolymer as compared with immiscible system of syndiotactic polystyrene in the main chain and atactic polyisoprene in the side chain. The contents of the SSTM in the graft copolymer was influenced by the MAO/Ti mole ratio and content of the SSTM in the comonomer feed. Received: 9 November 1999/Revised version: 24 November 1999/Accepted: 6 December 1999     

Rheology, morphology and tensile properties of reactive compatibilized polyethylene/polystyrene blends via Friedel–Crafts alkylation reaction

Attempts were made to study the effect of reactive compatibilization via Friedel?CCrafts alkylation reaction, using AlCl₃ as a catalyst, on rheology, morphology, and mechanical properties of polyethylene/polystyrene (PE/PS) blends. The results of linear viscoelastic measurements in conjunction with the results of the mixing torque variation indicated that PS showed much more degradation than that of PE in the presence of AlCl₃. It was also found that while for PE-rich blends, the viscosity, and storage modulus increased by reactive compatibilization, they decreased for PS-rich blends. The variation of viscosity and storage modulus for 50/50 blend was found to be dependent on frequency ranges showing the competitive effects of PE?Cg?CPS copolymer formation and PS degradation. The results of morphological studies showed that reactive compatibilization decreased the particle size and particle-size distribution broadness because of in situ graft copolymer formation. Reactive compatibilization enhanced the tensile strength and elongation at break for PE-rich blends. It was demonstrated that there is a close interrelationship between rheology, morphology, and mechanical properties of reactive compatiblized PE/PS blends. It was also demonstrated that rheological behaviors have a reliable sensitivity to follow the structural and morphological changes during compatibilization process, so that, those information can be used to predict the morphology as well as mechanical properties of the blends.     

Premade vs. reactively formed compatibilizers for PMMA/PS melt blends

The efficiency of two compatibilization methods, adding premade copolymers versus in situ formation of copolymers, were compared by evaluating the minor phase size and size distribution. Premade diblock copolymers were formed by coupling amine terminal polystyrene (PS-NH₂) with anhydride terminal poly(methyl methacrylate) (PMMA-An) in solution. Mid-functional PMMA was coupled with the PS-NH₂ to form graft copolymers. The same block and graft copolymers were formed in situ during melt blending. After mixing, the particle size and distribution were analyzed by transmission electron microscope (TEM). While both methods compatibilized blends, in situ formation reduced the minor phase size further. For the reactive case, graft copolymers are slight better than the block ones. This is attributed to a greater capacity for reducing interfacial tension. For the premade case, block copolymers compatibilize better at low copolymer concentration while graft copolymers work better at high concentration. As the amount of block copolymers added into the blends increases, the number of micelles increases significantly. This is believed to be the reason why premade copolymers are less capable of compatibilizing blends than the reactively formed ones.