Copolymer Compatibilizer Research Articles

The Influence of the compatibilizer Characteristics on the interfacial characteristics and phase morphology of aPA/SAN blends

The main objective of this work is study the influence of the methyl mathacrylate maleic anhydride copolymer (MMA-MA) compatibilizer properties such as molecular weight and maleic anhydride content in the characteristics of amorphous polyamide and styrene acrylonitrile copolymer (aPA/SAN) blends, correlating their interfacial characteristics and phase morphology. The blends aPA/SAN, with and without the compatibilizer, prepared were characterized by transmission electron microscopy (TEM) and small angle X-rays scattering (SAXS). The results show that the maleic anhydride concentration has a more significant effect on the blend properties than the molecular weight of the MMA-MA copolymer. Even though the system aPA/SAN is thermodynamically immiscible, it shows morphology of phases with small particles of SAN. The addition of MMA-MA copolymer with high degrees of MA led to an increase of the SAN phase particle size. With SAXS technique, it was possible to determine the interface thickness and the results shows that the characteristics of the interface do not change with the variation of the compatibilizer characteristics. The results observed in this work indicate that the viscosity ratio is very important factor on the formation of the phase morphology.

Engineering Nanostructured Polymer Blends with Controlled Nanoparticle Location using Janus Particles

Janus particles are used on a multigram scale for the blend compatibilization of two polymers in a twin screw mini-mixer. It is shown that the Janus particles can be located exclusively at the interface of the two polymer phases despite the high temperature and shear conditions. The domain sizes of the dispersed phase decrease with increasing content of Janus particles. The decrease is yet ongoing for high contents of Janus particles. Furthermore, the biphasic particles exhibit an ordered arrangement at the interface. Thus, the approach demonstrates that a nanoscopic structuring of the interface can be achieved under macroscopic processing conditions. The structural order occurs on two levels. The first is the complete adsorption at the interface and the second is the lateral ordering at the interface. The strong adsorption at the interface is explained in terms of the increased desorption energy of Janus particles. Secondly, the compatibilization efficiency is critically compared to state-of-the-art compatibilizers. The efficiency of the Janus particles is found to be superior as compared to block copolymer-based compatibilizers. The efficiency gap between Janus particles and block copolymer compatibilizers widens for larger amounts added.

Rheological properties of poly(dimethylsiloxane)-poly(diethylsiloxane) blends

The rheological behavior of poly(dimethylsiloxane)-poly(diethylsiloxane) blends in the range 20 to 100°C, including the region of existence of poly(diethylsiloxane) in mesomorphic and amorphous states has been studied by capillary viscometry. The flow of these blends within the studied shear stress interval between 103 and 105 Pa obeys a power law. If poly(diethylsiloxane) is introduced in the mesomorphic state and serves as a matrix, the blends behave as viscoplastic bodies and feature the yield stress. The flow of these blends is accompanied by an appreciable orientation of the poly(diethylsiloxane) phase. Blends in which the mesomorphic poly(diethylsiloxane) is a disperse phase flow as abnormally viscous fluids in which poly(diethylsiloxane) plays the role of a structuring filler. The isotropization of poly(diethylsiloxane) leads to a reduction in its viscosity and, accordingly, in the viscosity of the blend. The logarithm of the effective viscosity of such blends both at the constant shear rate and constant shear stress is the linear function of their composition. The addition of poly(diethylsiloxane) to poly(dimethylsiloxane) strongly affects the degree of swelling of an extrudate at the exit of a capillary, and this parameter depends on the phase state of poly(diethylsiloxane) and its content in the blend. Upon incorporation of a small amount of a poly(dimethysiloxanel)-poly(diethylsiloxane) block copolymer (compatibilizer) into the blend, the viscosity of the blend approaches that of the predominant component. This phenomenon is apparently related to the fact that the block copolymer facilitates development of a more uniform morphology of the blend, in particular, the continuous dispersion phase. This factor, along with the specifics of the deformational behavior of poly(diethylsiloxane), also manifests itself during drawing and subsequent shrinkage of crosslinked resins prepared from the blends under study.

The effect of zinc oxide addition on the compatibilization efficiency of maleic anhydride grafted high‐density polyethylene compatibilizer for high‐density polyethylene/polyamide 6 blends

AbstractA high‐density polyethylene with grafted maleic anhydride units has been investigated as a compatibilizer for high‐density polyethylene with polyamide 6. The material acts as an effective compatibilizer, causing a marked reduction in dispersed phase size as well as an increase in tensile strength and toughness. Compatibilizer also affects the glass‐transition temperature, crystallization kinetics, and amount of crystalline material for certain blend compositions. The addition of zinc cations, which are effective in increasing ethylene‐acid copolymer compatibilizer performance in low‐density polyethylene/polyamide blends, has little, if any, effect on compatibilizer performance in these high‐density polyethylene/polyamide blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3871–3881, 2007

Flow deformation of polymer blend droplets and the role of block copolymer compatibilizers

We use a multiscale Brownian dynamics simulation approach to study the influence of block copolymer compatibilizers upon the dynamics of a nanoscale polymer droplet in a matrix of another polymer. The present study focuses on the influence of the physical characteristics of the copolymer, viz. its coverage and chain lengths upon the droplet deformation characteristics and the rheological properties of the polymer blend system. At a fixed chain length, the copolymer coverage is found to affect the droplet deformation in a nonmonotonic manner as a function of the capillary number, while it increases monotonically with an increase in the copolymer chain length at a fixed coverage. We identify the interplay between interfacial tension reduction, bending modulus enhancement, and Marangoni stresses as responsible for the preceding characteristics. We also study the rheological effects arising from the presence of block copolymers. Our results suggest increased shear thinning with either increasing the copolymer coverage or the copolymer chain lengths. Moreover, the normal stresses of the mixture are dominated by the inherent normal stresses of the matrix and the droplet phases. The rheological results are rationalized by invoking the interplay between deformation characteristics and the dynamical effects of block copolymers at polymer blend interfaces.

Mechanical properties of short flax fibre bundle/poly(ε-caprolactone) composites: Influence of matrix modification and fibre content

Composites were prepared by mixing biodegradable poly(ε-caprolactone) thermoplastic (PCL) with short flax fibre bundles. In order to improve fibre/matrix adhesion, poly(ε-caprolactone)- g-maleic anhydride copolymer (PCL- g-MA) compatibilizer was prepared in an internal mixer. The grafting reaction of maleic anhydride (MA) onto PCL polymer was carried out in presence of dicumyl peroxide as initiator. Mechanical properties were analysed as a function of compatibilizer concentration and fibre amount. In addition, thermal properties of flax/PCL and flax/PCL- g-MA composites were also examined by thermogravimetric (TG) analysis. Composites fabricated with flax fibre bundles and PCL- g-MA matrix showed the highest tensile and flexural strength. Scanning electron microscopy (SEM) of fractured surfaces confirmed the adhesion improvement between flax fibre bundles and PCL- g-MA matrix. Results obtained by thermogravimetric analysis showed that fibre addition and matrix modification slightly reduced the thermal stability of composites. The correlation between the experimental mechanical properties of short flax fibre bundle reinforced PCL composites with values calculated by various empirical models has also been analysed. For composites based on PCL- g-MA matrix, a good agreement was found between empirical model and experimental values for all fibre contents. However, for composites based on PCL matrix a good agreement only existed until 20 wt% flax fibre content, and beyond this value, experimental strength felt well below predictions.

Amphiphilic Diblock Copolymer Compatibilizers and Their Effect on the Morphology and Performance of Polythiophene:Fullerene Solar Cells

A diblock copolymer containing a fullerene(C60)-rich block and a poly(3-hexylthiophene) block functions as a compatibilizer in poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) blends. The copolymer is used to probe the impact of morphology and phase-segregation kinetics on the performance of P3HT:PCBM-based solar cells. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2089/2006/c1787_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Effects of the chemical foaming agents, injection parameters, and melt‐flow index on the microstructure and mechanical properties of microcellular injection‐molded wood‐fiber/polypropylene composites

AbstractWood‐fiber‐reinforced plastic profiles are growing rapidly in nonstructural wood‐replacement applications. Most manufacturers are evaluating new alternative foamed composites, which are lighter and more like wood. Foamed wood composites accept screws and nails better than their nonfoamed counterparts, and they have other advantages as well. For example, internal pressures created by foaming give better surface definition and sharper contours and corners than nonfoamed profiles have. In this study, the microfoaming of polypropylene (PP) containing hardwood fiber was performed with an injection‐molding process. The effects of different chemical foaming agents (endothermic, exothermic, and endothermic/exothermic), injection parameters (the mold temperature, front flow speed, and filling quantity), and different types of PP (different melt‐flow indices) on the density, microvoid content, physicomechanical properties, surface roughness, and microcell classification of microfoamed PP/wood‐fiber composites were studied. A maleic anhydride/polypropylene copolymer (MAH‐PP) compatibilizer was used with the intention of improving the mechanical properties of microfoamed composites. The microcell classification (from light microscopy) and scanning electron micrographs showed that an exothermic chemical foaming agent produced the best performance with respect to the cell size, diameter, and distance. The polymer melt‐flow index and the variation of the injection parameters affected the properties and microstructure of the microfoamed composites. The density of the microfoamed hardwood‐fiber/PP (with a high melt‐flow index) composites was reduced by approximately 30% and decreased to 0.718 g/cm3 with an exothermic chemical foaming agent. Tensile and flexural tests were performed on the foamed composites to determine the dependence of the mechanical properties on the density and microvoid content of the foamed specimens, and these properties were compared with those of nonfoamed composites. MAH‐PP improved the physicomechanical properties up to 80%. With an increase in the mold temperature (80–110°C), the surface roughness was reduced by nearly 70% for the foamed composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1090–1096, 2005

Interfacial Phenomena in Polymer Blends: A Self-Consistent Brownian Dynamics Study

We apply a recently proposed multiscale simulation approach to study the dynamical properties of polymer blend interfaces. We use this approach to study the influence of the bulk rheological properties of the polymer blend components upon the slip at unentangled polymer interfaces. Our numerical results agree quite well with the predictions from scaling approaches and phenomenological theories. Moreover, these results also provide a microscopic explanation of the negatively deviating viscosities of polymer blends. We also present results elucidating the slip suppressing influence of block copolymer compatibilizers. Our results suggest that even trace fractions of compatibilizers can suppress slip at polymer interfaces. We study the influences of the molecular weight of the block copolymer and the coverage of block copolymers upon the dynamical properties of polymer blend interfaces, and we suggest some effects that might account for the effect of compatibilizers in the suppression of coalescence during polymer blending.

Block copolymer compatibilization of cocontinuous polymer blends

The effect of block copolymers on the cocontinuous morphology of 50/50 (w/w) polystyrene (PS)/high density polyethylene (HDPE) blends was investigated using symmetric polystyrene–polyethylene block copolymers (PS–PE) with molecular weights varying from 6 to 200 kg/mol. The coarsening rate during annealing was compared to the Doi–Ohta theory. An intermediate molecular weight PS–PE, 40 kg/mol, showed remarkable results in reducing the phase size and stabilizing the blend morphology during annealing. Mixing small amounts of 6, 100 or 200 kg/mol PS–PE in the blend did not reduce the phase size significantly, but did decrease the coarsening rate during annealing. In stabilizing the morphology, 6 kg/mol PS–PE was inferior to 100 and 200 kg/mol. The existence of an optimal molecular weight block copolymer is due to a balance between the ability of the block copolymer to reach the interface and its relative stabilization effect at the interface.

Continuous Mixing and Compounding of Polymer/Filler and Polymer/Polymer Mixtures with the Aid of Ultrasound

Abstract High power ultrasound is applied to break down silica agglomerates in EPDM/silica mixtures and to compatibilize plastic/rubber and rubber/rubber blends during extrusion process. Ultrasonically treated EPDM/silica mixtures without silane treatment of silica indicated significantly reduced sizes of silica agglomerates in comparison with those obtained by an internal mixer and lower than the EPDM/silica mixtures treated by the silane. The viscosity of the ultrasonically treated mixtures was found to be higher than that of the silane treated mixtures, while the extrudate swells of both mixtures were close to each other. Ultrasonically treated plastic/rubber and rubber/rubber blends indicated in-situ copolymer formation and compatibilization in the melt state leading to significant enhancement of the mechanical properties of the blends. An idea is put forward about the possibility of in-situ copolymer formation at the interfaces and their vicinities in the ultrasonically treated blends during extrusion. Data obtained by a solvent extraction indicating reduction in the amount of the extractable component, gel permeation chromatography indicating formation of the high molecular weight tail, atomic force microscopy indicating smooth interfacial region and scanning electron microscopy indicating stabilization of the phase morphology in the melt state of the ultrasonically treated blends point towards the occurrence of in-situ copolymer formation. The discovery creates a new field of the study of ultrasonic-assisted mixing of rubber with filler and compatibilization of immiscible polymer blends during extrusion.

Morphology control in co-continuous poly(L-lactide)/polystyrene blends: a route towards highly structured and interconnected porosity in poly(L-lactide) materials.

Poly(L-lactide) is a biodegradable polymer primarily used in biomedical applications. In this paper, both the microstructure and the region of dual-phase continuity are examined for binary and compatibilized poly(L-lactide)/polystyrene blends (PLLA/PS) prepared by melt mixing. The blends are shown to be completely immiscible with an interfacial tension of 6.1 mN/m. The PS-b-PLLA (24,000-b-28,000) diblock copolymer compatibilizer has an asymmetric effect on the blend. It is effective at compatibilizing 50/50 PLLA/PS blends but is only a marginal emulsifier for blends where PLLA is the dominant matrix. Percent continuity, as estimated by solvent extraction/gravimetry and also torque/composition diagrams clearly indicate an onset of the region of dual-phase continuity at 40-45%PS. It is demonstrated that highly percolated blends of the above materials exist from 40 to 75% PS and 40 to 60% PS for the binary and compatibilized blends, respectively. The scale of the microstructure of the continuous morphology is measured using BET and mercury intrusion porosimetry techniques, after extraction of the PS phase. Both the pore size and extent of continuity can be controlled through composition and interfacial modification. Static annealing of the blend after melt mixing can also be used to substantially increase the pore size of the system. Extraction of the PS phase in the blend, carried out after the above preparation protocols, is a route to generating completely interconnected porosity of highly controlled morphologies (pore size, void volume) in poly(L-lactide) materials. In this study, the pore diameter was controlled from 0.9 to 72 microm for a constant void volume of 45-47%, and the void volume was modified from 35 to 74% depending on the blend composition.

Suppression of phase‐separation pattern formation in blend films with block copolymer compatibilizer

Journal of Polymer Science Part B: Polymer PhysicsVolume 41, Issue 14 p. 1697-1700 Letter Suppression of phase-separation pattern formation in blend films with block copolymer compatibilizer L. Sung, L. Sung Building Materials, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Search for more papers by this authorJ. F. Douglas, Corresponding Author J. F. Douglas Jack.Douglas@nist.gov Polymers Divisions, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Building Materials, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Search for more papers by this authorC. C. Han, C. C. Han Polymers Divisions, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Search for more papers by this authorA. Karim, Corresponding Author A. Karim alamgir.karim@nist.gov Building Materials, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Building Materials, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Search for more papers by this author L. Sung, L. Sung Building Materials, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Search for more papers by this authorJ. F. Douglas, Corresponding Author J. F. Douglas Jack.Douglas@nist.gov Polymers Divisions, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Building Materials, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Search for more papers by this authorC. C. Han, C. C. Han Polymers Divisions, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Search for more papers by this authorA. Karim, Corresponding Author A. Karim alamgir.karim@nist.gov Building Materials, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Building Materials, National Institute of Standards and Technology, Gaithersburg, Maryland 20899Search for more papers by this author First published: 11 June 2003 https://doi.org/10.1002/polb.10519Citations: 6Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume41, Issue1415 July 2003Pages 1697-1700 RelatedInformation

Compatibilization and property characterization of polycarbonate/polyurethane polymeric alloys

AbstractPolymeric alloys of bisphenol A polycarbonate and a polyester‐type polyurethane were prepared over a complete composition range through melt mixing. The blends were characterized with optical and scanning electron microscopy, tensile testing, dynamic mechanical analysis, thermal analysis (differential scanning calorimetry and thermogravimetric analysis), and spectroscopic techniques (Fourier transform infrared and 1H‐NMR). A morphology examination revealed good component dispersion with 30 wt % polyurethane or less and strong interface adhesion. Dynamic mechanical analysis indicated partial component miscibility and tensile testing mechanical behavior typical of a polymeric alloy. Overall, the degree of compatibilization obtained with polycarbonate was lower than that observed previously with poly(ethylene terephthalate) or poly(butylene terephthalate). This was attributed to the lower reactivity of the aromatic OH of polycarbonate toward the isocyanate groups of polyurethane and the thermal instability of the copolymer–compatibilizer formed. Experimental evidence for the formation of the latter was provided by 1H‐NMR and dynamic mechanical analysis of selectively leached blends and by quantitative analysis results for the extraction experiments. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 612–626, 2003

Novel ultrasonic process for in‐situ copolymer formation and compatibilization of immiscible polymers

AbstractIn‐situ copolymer formation and compatibilization of immiscible polymers in blends were discovered to occur during ultrasonic‐assisted extrusion in the melt state under high pressures. Residence times were of the order of seconds. The mechanical performance of plastic/rubber and rubber/rubber blends subjected to ultrasonic treatment was significantly enhanced compared to those of identical blends not subjected to ultrasonic treatment and having similar phase morphologies. The appearance of a high molecular weight tail in the rubber/rubber blends, stabilization of phase morphology in the melt state, the presence of a transition interface nanolayer and a decrease in the amount of extractable components in the plastic/rubber blends after ultrasonic‐assisted extrusion point towards the occurrence of in‐situ copolymer formation at the interfaces.

Structural effects of compatibilizer localization and effectivity in thermoplastic polyurethane–polyolefin blends

AbstractA study was performed with blends of thermoplastic polyurethanes and polyolefins to determine the structural requirements for a compatibilizer to be located at the interface. It was demonstrated that during the addition of an incompatible polymeric additive (i.e., incompatible with both blend constituents) to a polyurethane–polyolefin blend, the additive migrated to the interface. This interfacial phenomenon was proven to be virtually independent of compatibilizer viscosity or surface activity. Only when the compatibilizer was quite comparable to one of the phases did small differences in polarity govern whether the compatibilizer remained at the interface or formed micelles. This effect was demonstrated with a series of styrene–(ethylene–butylene)–styrene block copolymer compatibilizers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2901–2905, 2002; DOI 10.1002/app.10285

Phase separation in gelatin/maltodextrin and gelatin/maltodextrin/gum arabic mixtures studied using small-angle light scattering, turbidity, and microscopy.

The kinetics of phase separation were observed in the gelatin/maltodextrin and gelatin/maltodextrin/gum arabic systems, where gum arabic was added as a minority component, using small-angle light scattering, turbidity measurement, and confocal scanning laser microscopy. Phase separation occurred by spinodal decomposition for quenches both above and below the temperature at which gelatin gelled. Coarsening of the phase-separated microstructure was hindered by gelation, and a hydrodynamic mechanism, observed when the gelatin remained in the liquid state, was suppressed. Gum arabic, containing both polysaccharide and polypeptide components, was hypothesized to be potentially interfacially active in the gelatin/maltodextrin system, in analogy with synthetic block copolymer compatibilizers in demixed synthetic polymer systems. The hypothesis was experimentally refuted under the chosen experimental conditions, as no evidence was found to suggest that it altered the phase separation behavior.

Suppression of Lateral Phase Separation in Thin Polyolefin Blend Films

The effectiveness of a compatibilizer in suppressing lateral phase separation in thin polyolefin blend films is investigated as a function of film thickness and temperature. Neutron and X-ray reflectivity measurements were made on spun-cast thin blend films of partially deuterated and hydrogenated polyolefin blends with and without diblock compatibilizer. We use an extended silicon surface passivating treatment. Under these biased symmetric wetting conditions (air vs hydrophobic Si), binary blend films are stabilized against both dewetting from the substrate and roughening of the surface due to phase separation when the film thickness (25 nm) is on the order of the molecular radius of gyration. However, thicker (100 nm) films exhibit lateral phase separation that can be suppressed by the addition of block copolymer compatibilizer. This stabilization effect can be attributed to the reduction of interfacial tension leading to a broadening of interfaces, and additionally, the presence of diblock copolymer in both phases alters their surface interactions. On longer time scales, optical micrographs show the development of large-scale features over the course of a year in the molecularly thin blend films and in the ternary thin film (stored under vacuum). A droplet morphology is observed for molecularly thin blend films, and an interconnected domain structure characteristic of the early and intermediate stages of phase separation is observed for the ternary thin blend film. The phase separated structure obtained for the binary thin blend film does not evolve with time. Our results indicate that one also needs to account for kinetics in order to develop a comprehensive understanding of the structure of thin blend films. In general, temperature has a weak effect on the profile development of compatibilized blend films.

The early stage of the morphology development of immiscible polymer blends during melt blending: Compatibilized vs. uncompatibilized blends

The early stage of the morphology development has been studied for the blending of two immiscible polymers. Controlled experiments were carried out in a batch mixer in such a way that the rate of melting was low enough to follow up the morphology development of dilute and concentrated systems. For a dilute or semidilute polypropylene and polyamide 6 (PP/PA6) blend with 0.5, 5, or 10 wt % PA6, particles formed in the very early stage of melt blending were very small, of the order of 0.25 to 0.3 μm in radius. They immediately began to grow in size when no compatibilizer was added, indicative of coalescence even in the very early stage of melt blending and/or in very dilute systems (0.5 wt % PA6). Further growth of the particles was eliminated with the introduction of a graft copolymer compatibilizer providing evidence of the stabilizing effect of the copolymer from the very beginning of melting blending. However, the behavior of the morphology development of a concentrated PP/PA6 (80/20) system was similar to that reported in the literature. The average radius of the particles of the uncompatibilized blend decreased with increasing mixing time, whereas that of the compatibilized blend remained almost constant during mixing. The most favorable conditions to obtain a fine morphology seems to be the following: rate of melting/plastification of pellets < rate of dispersion (deformation + breakup) of the polymer melt to small particles < rate of stabilization (with an adequate copolymer). © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 601–610, 2001

Crystallization and morphology of fibers prepared from compatibilized blends of polyethylene with a liquid crystalline polymer

Fibers prepared by melt spinning of compatibilized blends of high-density polyethylene (HDPE) with a semiflexible liquid crystalline polymer (LCP) SBH 1 : 1 : 2 of Eniricerche, Italy, have been investigated by differential scanning calorimetry (DSC) and optical microscopy. Two grades of HDPE with different molar mass have been used to prepare the blends. The compatibilizers are an acrylic acid functionalized polyethylene (Escor 5 000 by Exxon) and an ad hoc synthesized graft copolymer of the liquid crystalline polymer grafted to Escor 5 000 (PE-g-SBH). The studies cover the non-isothermal and isothermal crystallization, and the morphology of the fibers. The influence of the matrix molar mass and the maximal draw ratio of the fibers upon PE crystallization rate have been established. It has been shown that the overall PE crystallization rate under non-isothermal and isothermal conditions increases for fibers prepared from blends of lower molar mass HDPE, compatibilized by PE-g-SBH copolymer. The dispersed LCP phase in the latter fibers due to the enhanced interfacial adhesion in the presence of the copolymer compatibilizer appears as fibrils with high aspect ratio. The results have been interpreted by an increase in interfacial area between the SBH fibrils and the matrix phase, which enlarges the number of heterogeneous nuclei and increases the PE nucleation rate. These effects are less pronounced for the fibers compatibilized with Escor, due to the lower draw ratio of the fibers and to the lower aspect ratio of the SBH fibrils.