Interplay of crystallization and liquid-liquid phase separation in polyolefin blends: A thermal history dependence study

The kinetic interplay between crystallization and liquid-liquid phase separation (LLPS) in random copolymer blends of poly(ethylene-ran-hexene) (PEH) and poly(ethylene-ran-butene) (PEB) has been studied using optical microscopy. Morphologies of blends gone through three different thermal histories are compared: (1) single-quench (SQ), a homogeneous melt quickly cooled to isothermal crystallization temperatures (T_cry), (2) double-quench (DQ), a homogeneous melt quickly cooled to an intermediate temperature (T_lps) between binodal and equilibrium melting temperature (T_m⁰) and stored for a period of time and then cooled to T_cry, and (3) cyclic-quench (CQ), a homogeneous melt quickly cooled to T_lps and stored for a period of time, then gone through four cycles of crystallization and remelting. Comparing DQ morphologies to SQ ones, both crystal growth rate and nucleation density in the former are affected by prior LLPS. A scaling argument has been provided to partially account for the observed phenomena. In CQ, characteristic lengths of secondary features induced by crystallization depend strongly on the overall PEH composition, whereas are insensitive to temperature cycling. The contrast of large domains becomes more prominent upon cyclic crystallization and remelting. On the other hand, primary LLPS domains coarsen with CQ while loosing the contrast.     

Kinetics of phase separation and crystallization in poly(ethylene-ran-hexene) and poly(ethylene-ran-octene)

The kinetics of phase separation and crystallization in the blends of poly(ethylene-ran-hexene) (PEH) and poly(ethylene-ran-octene) (PEOC) at several compositions were studied using phase contrast optical microscopy and time-resolved simultaneous small-angle X-ray scattering and wide-angle X-ray diffraction. The phase contrast optical microscopy showed the interconnected bicontinuous structure during phase separation process, which is characteristic of a spinodal decomposition. During isothermal crystallization, the average lamellar spacing increases with time for blends at all concentrations. The crystallinity and crystal growth rate depend on the PEH concentration. At dilute PEH concentrations, crystallization of PEH chains is difficult because they are surrounded by many non-crystallizable PEOC chains. On the other hand, at higher PEH concentrations, crystallization processes are similar to pure PEH. For example, the spherulitic growth rates are similar for a PEH/PEOC=50/50 blend and pure PEH.     

Phase separation of polystyrene-b-(ethylene-co-butylene)-b-styrene (SEBS) deposited on polystyrene thin films

Phase separation of a triblock copolymer, polystyrene-b-(ethylene-co-butylene)-b-styrene (SEBS) on the thin films of a homopolymer, polystyrene (PS), was studied by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The final morphology after phase separation was found to be greatly dependent on the relation between the molecular weight of the PS block and homo-PS. Dispersed spherical and worm-like micelles of SEBS were observed when the molecular weight of homo-PS is smaller than the PS block in SEBS, while large structures with inner micro-phase separation of SEBS was found when the molecular weight of homo-PS was much higher than that of the PS block. The origin of such a change in morphology is attributed to the difference of structure and interfacial tension at the interface between the matrix homo-PS and the PS block in SEBS triblock copolymer assembly.     

Miscibility and crystallization of biodegradable poly(butylene succinate-co-butylene adipate)/poly(vinyl phenol) blends

Miscibility, crystallization kinetics, crystal structure, and microstructure of biodegradable poly(butylene succinate-co-butylene adipate) (PBSA)/poly(vinyl phenol) (PVPh) blends were studied by differential scanning calorimetry, optical microscopy, wide angle X-ray diffraction, and small angle X-ray scattering in detail in this work. PBSA and PVPh are miscible as evidenced by the single composition dependent glass transition temperature and the negative polymer-polymer interaction parameter. Isothermal crystallization kinetics of PBSA/PVPh blends was investigated and analyzed by the Avrami equation. The overall crystallization rates of PBSA decrease with increasing crystallization temperature and the PVPh content in the PBSA/PVPh blends; however, the crystallization mechanism of PBSA does not change in the blends. Furthermore, blending with PVPh does not modify the crystal structure of PBSA. The microstructural parameters, including the long period, thickness of crystalline phase and thickness of amorphous phase, all become larger with increasing the PVPh content, indicating that PVPh mainly resides in the interlamellar region of PBSA spherulites in the blends.     

Morphology of polypropylene/poly(ethylene-co-propylene) in-reactor alloys prepared by multi-stage sequential polymerization and two-stage polymerization

The morphology of two polypropylene/poly(ethylene-co-propylene) (PP/EPR) in-reactor alloys prepared by multi-stage sequential polymerization (MSSP) and two-stage polymerization (TSP) processes, respectively, was investigated. It is observed that the alloy prepared by MSSP (sample 1) exhibits lower phase separation temperature than the alloy prepared by TSP (sample 2), probably due to the higher content of PP segments in the blocky copolymer fractions of sample 1. Two thermal treatments were applied to the samples: (1) The samples were directly quenched from 230 °C to 132 °C for isothermal crystallization; (2) The samples were firstly held at 160 °C for 60 min for phase separation and then cooled to 132 °C for crystallization. It is found that both microstructure and thermal treatment affect the morphology of the alloys, and the differences in morphology are interpreted in terms of phase diagram. For sample 1 and for the samples subjected to phase separation prior to crystallization, the EPR-rich phase contains more PP and thus is more viscous, which leads to more inclusion of the EPR-rich phase into the spherulites. A coarse spherulitic structure is formed due to crystallization of PP in the included EPR-rich phase. More included EPR-rich phase and its stronger crystallizability can further lead to the narrower boundaries and formation of connections between the adjacent spherulites.     

Dynamic interplay between phase separation and crystallization in a poly(?-caprolactone)/poly(ethylene glycol) oligomer blend

We have investigated the crystallization effect on the phase separation of a poly(?-caprolactone) and poly(ethylene glycol) oligomer (PCL/PEGo) blending system using simultaneous small-angle light scattering and differential scanning calorimetry (SALS/DSC) as well as simultaneous small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and DSC (SAXS/WAXS/DSC). When the PCL/PEGo system, of a weight ratio of 7/3, is quenched from a melt state (160 °C) to temperatures below the spinodal point and the melting temperature of PCL (63 °C), the structural evolution observed exhibits characteristics of (I) early stage of spinodal decomposition (SD), (II) transient pinning, (III) crystallization-induced depinning, and (IV) diffusion-limited crystallization. The time-dependent scattering data of SALS, SAXS and WAXS, covering a wide range of length scale, clearly show that the crystallization of PCL intervenes significantly in the ongoing viscoelastic phase separation of the system, only after the early stage of SD. The effect of preordering before crystallization revives the structural evolution pinned by the viscoelastic phase separation. The growth of SAXS intensity during the preordering period conforms to the Cahn-Hilliard theory. In the later stage of the phase separation, the PCL-rich matrix, of spherulite crystalline domains developed due to the faster crystallization kinetics, traps the isolated PEGo-rich domains of a slower viscoelastic separation.     

Fluctuation-assisted nucleation in the phase separation/crystallization of iPP/OBC blends

This work mainly focused on the nucleation behavior in iPP/OBC (isotactic polypropylene/polyolefin block copolymers) blends with two distinct OBCs. The influence of composition and molecular structure of the OBC component on the crystallization kinetics of the blends was investigated systematically with the aim to better understand the interplay between the two coupled phase transitions in the blends: macrophase separation and crystallization. The isothermal crystallization kinetics showed component and composition dependence in iPP/OBC blends. All the blends in the studied range have enhanced nucleation ability of iPP than the pure iPP under identical conditions. Furthermore, the distinct macrophase separation morphology resulting from the different compatibility between the various OBCs and iPP caused remarkable diversity between the blends: the nuclei density is qualitatively higher (or the nucleation rate is qualitatively faster) in the more compatible blends, and this enhancement of nucleation can be depressed by imposing a macrophase separation process before crystallization. The crystal nuclei from the phase separated matrix were preferentially formed at the interface of the phase domains, and then grew toward and into the iPP-rich phase. It is postulated that the increased nuclei density and/or nucleation rate followed the fluctuation-assisted nucleation mechanism: the enhanced concentration fluctuation at the interfacial area created by the spinodal decomposition played an important role in the nucleation behavior of iPP/OBC blends. The decreased interface areas with increased domain sizes after deeper phase separation, coupled with a more depressed concentration fluctuation, are responsible for lower nuclei density after long time annealing for phase separation.     

Liquid-liquid phase separation and crystallization behavior of poly(ethylene terephthalate)/poly(ether imide) blend

The liquid-liquid (L-L) phase separation and crystallization behavior of poly(ethylene terephthalate) (PET)/poly(ether imide) (PEI) blend were investigated with optical microscopy, light scattering, and small angle X-ray scattering (SAXS). The thermal analysis showed that the concentration fluctuation between separated phases was controllable by changing the time spent for demixing before crystallization. The L-L phase-separated specimens at 130 °C for various time periods were subjected to a temperature-jump of 180 °C for the isothermal crystallization and then effects of L-L phase separation on crystallization were investigated. The crystal growth rate decreased with increasing L-L phase-separated time (t_s). The slow crystallization for a long t_s implied that the growth path of crystals was highly distorted by the rearrangement of the spinodal domains associated with coarsening. The characteristic morphological parameters at the lamellar level were determined by the correlation function analysis on the SAXS data. The blend had a larger amorphous layer thickness than the pure PET, indicating that PEI molecules in the PET-rich phase were incorporated into the interlamellar regions during crystallization.     

Acceleration or retardation to crystallization if liquid-liquid phase separation occurs: Studies on a polyolefin blend by SAXS/WAXD, DSC and TEM

Blends of statistical copolymers containing ethylene/hexene (PEH) and ethylene/butene (PEB) exhibited the behavior of upper critical solution temperature (UCST). The interplay between the early and intermediate stage liquid-liquid phase separation (LLPS) and crystallization of the PEH/PEB 50/50 blend was studied by time-resolved simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. Samples were treated by two different quench procedures: in single quench, the sample was directly quenched from 160 °C to isothermal crystallization temperature of 114 °C; while in double quench, the sample was firstly quenched to 130 °C for 20 min annealing, where LLPS occurred, and then to 114 °C. It was found that in the early stage of crystallization, the integrated values of Iq² and crystallinity, X_c, in the double quench procedure were consistently higher than those in the single quench procedure, which could be attributed to accelerated nucleation induced by enhanced concentration fluctuations and interfacial tension. In the late stage of crystallization, some morphological parameters were found to crossover and then reverse, which could be explained by retardation of lamellar growth due to phase separation formed during the double quench procedure. This phenomenon was also confirmed by DSC measurements in blends of different compositions at varying isothermal crystallization temperatures. The crystal lamellar thickness determined by SAXS showed a good agreement with TEM observation. Results indicated that the early stage LLPS in the PEH/PEB blend prior to crystallization indeed dictated the resulting lamellar structures, including the average size of lamellar stack and the stack distribution. There seemed to be little variation of lamellar thickness and long period between the two quenching procedures (i.e., single quench versus double quench).     

Microphase separation and crystallization in mixtures of polystyrene-poly(methyl methacrylate) diblock copolymer and poly(vinylidene fluoride)

This study examined the microdomain structures and the crystallization behavior in binary blends consisting of an asymmetric block copolymer and a homopolymer using small-angle X-ray scattering, optical microscopy and differential scanning calorimetry. A polystyrene-block-poly(methyl methacrylate) copolymer (PS-b-PMMA) was mixed with a low molecular weight poly(vinylidene fluoride) (PVDF), where the PS-b-PMMA had a 0.30 wt fraction of the PMMA block. At a PVDF concentration of <13.0 wt%, the PVDF was completely miscible with the PMMA microdomains, and the blends had a cylindrical structure. The addition of PVDF altered the morphology from a PMMA-cylindrical structure to a lamellar structure and finally to a PS-cylindrical structure. When the PVDF concentration was <23.0 wt%, the PVDF was distributed uniformly within the PMMA microdomains. After adding more PVDF, some of the PVDF was locally dissolved in the middle of the PMMA microdomains. The addition of PVDF also affected the ordered microstructure in the blends, leading to a well-defined microdomain structure. However, PVDF crystallization significantly disturbed the pre-existing microdomain structure, resulting in a poorly ordered morphology. In the blends, PVDF had unique crystallization behavior as a result of the space constraints imposed by the microdomains.     

Shear-induced phase separation and crystallization in semidilute solution of ultrahigh molecular weight polyethylene: Phase diagram in the parameter space of temperature and shear rate

In the previous papers, we elucidated enhancement of concentration fluctuations, phase separation, and crystallization induced by steady state or step-up shear flow, as observed by shear small-angle light scattering, optical microscopy, and birefringence, for a semidilute solution of ultrahigh molecular weight polyethylene in paraffin as an athermal solvent. However the studies were done only at a given temperature of 124 °C, which is higher than the nominal melting temperature of the quiescent solution T_nm (115–119 °C). It is crucial to extend the studies over a wider temperature range in order to generalize shear-induced phase behavior of the solution. Thus in this work we constructed a kind of phase diagram in the parameter space of temperature (T) and shear rate (). The temperature range covered was higher than T_nm, so that the phase diagram is strictly concerned with shear-induced phase behavior (i.e., without shear the solution is homogeneous and in a single-phase state). The diagram identified Regimes I–III in the T– space as will be detailed in the text. In constructing the phase diagram we found the following new points also. (i) The critical shear rate _cx which defines the boundary between Regimes I and II was independent of T. (ii) Regime III identified previously through the dependence of the integrated scattered intensity only at a particular temperature T = 124 °C was further separated into two regimes of III_a and III_b below and above a critical temperature (147 °C), respectively, through the observation of the dependence as a function of T: In Regime III_a, the sheared solution developed the optically anisotropic fibrous structures, indicative of the shear-induced crystallization triggered by the shear-induced concentration fluctuations in Regime II; In Regime III_b, the solution is so stable that it did not show a trend of the shear-induced crystallization even at the highest shear rates accessible in this experiment, but it only showed the shear-induced phase separation. (iii) The critical shear rates _c,streak and _cz, which define respectively the boundary between Regimes II and III_a and that between Regimes II and III_b, are sensitive to temperature.     

Unveiling the evolution of early phase separation induced by P2O5 for controlling crystallization in lithium disilicate glass system

The nucleation and crystallization of glass-ceramics are typically influenced by early phase separation, which can impact glass properties. However, it has been challenging to characterize the nanoscale phase separation and understand the nucleation mechanism of lithium disilicate (L₂S) glass-ceramics, which has resulted in some controversy. Here, we raised the direct evidence of nanoscale clustering in the glassy phase prior to formal nucleation and crystallization by element distribution. Firstly, the amorphous Li₃PO₄ phase formed on the boundary between the phase separation area and residual glass matrix, and then nucleation tended to start on this phase boundary. Furthermore, the effect of phase-separation on nucleation and final crystallize products was illustrated. By sufficient phase-separation, the formation of desired Li₂Si₂O₅ and LiAlSi₄O₁₀ microcrystals was effectively motivated, which is prerequisite for high mechanical properties and transparency. We hope this work provides guidance to rationally understand the early phase separation in glass for subsequent controlling crystallization.     

Relation between liquid-liquid phase separation and crystallization in isotactic and syndiotactic polypropylene solutions

The effects of the stereospecificity of a polymer chain and of the interaction in polypropylene (PP) solutions on the relation between liquid-liquid phase separation and crystallization were investigated by using an isotactic PP (i-PP) and a syndiotactic PP (s-PP) of high stereoregularity and of similar molar mass. Dialkyl phthalate was used as a solvent. A series of dialkyl phthalates with a different number of carbon atoms in the alkyl chain was employed to control the interaction between polymer and solvent. Phase transition temperatures were measured by optical microscopy with a hot stage. Liquid-liquid phase separation temperature (T_L-L) in the system of i-PP and dihexyl phthalate was located below its melting temperature (T_m). However, T_L-L for the s-PP system in the same solvent was elevated much above its T_m due to a decreased T_m and increased T_L-L. The reduced solubility of s-PP is primarily attributed to enhanced hydrophobicity arising from alternate positioning of the methyl groups along the polymer chain. As the length of the alkyl chain in the phthalate increases, T_L-L decreases significantly and T_m decreases slightly, resulting in the value of T_L-L shifting below that of T_m for the solution of s-PP and dinonyl phthalate. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 159–163, 1998     

Phase separation of diamine chain-extended poly(urethane) copolymers: FTIR spectroscopy and phase transitions

As part of our continuing effort to understand microphase separation of poly(urethane urea) block copolymers, FTIR spectroscopy and thermal techniques (DSC and DMA) were used to investigate the phase behavior of two series of MDI-polytetramethylene oxide soft segment copolymers, chain-extended with ethylene diamine or a diamine mixture. Due to the complex nature and multiple absorbances in the carbonyl and N-H regions of the FTIR spectra, quantitative analysis was not possible. However, qualitative trends could be discerned, and the spectral changes were found to be in excellent agreement with our previous quantitative analysis of the same copolymers using small-angle X-ray scattering. DSC and DMA experiments both indicate that the soft phase T_g decreases with increasing hard segment content. This is contrary to increased hard segment mixing in the soft phase, but can be rationalized by taking into consideration soft segment crystallinity and the concentration of ‘lone’ MDI units in the soft phase.     

Preparation and membrane performance of poly(ethylene-co-vinyl alcohol) hollow fiber membrane via thermally induced phase separation

Poly(ethylene-co-vinyl alcohol) (EVOH) hollow fiber membranes with ultrafiltration performance were prepared from EVOH/glycerol systems via thermally induced phase separation (TIPS). The diluent glycerol was used as bore liquid to make a lumen of the hollow fiber for the purpose of prevention of the diluent evaporation and the larger pores formation at the inner surface of the hollow fiber. The obtained hollow fiber membranes showed asymmetric structures with skin layer near the outer surface, the larger pores just below the skin layer and the smaller pores near the inner surface. The formation of the larger pores near the outer surface was due to the enhanced pore growth by the water penetration. Some primary factors affecting the structure and performance of the membranes such as ethylene content (EC) in EVOH, cooling water bath temperature and take-up speed were studied extensively. The water permeability can be improved by increasing the water bath temperature and the take-up speed and by decreasing the EC. Both the pore size at the outer surface and the connectivity between the pores have to be considered together to understand the experimental result of the water permeability and the solute rejection.     

Miscibility and crystallization in crystalline/crystalline blends of poly(butylene succinate)/poly(ethylene oxide)

Miscibility and crystallization behavior have been investigated in blends of poly(butylene succinate) (PBSU) and poly(ethylene oxide) (PEO), both semicrystalline polymers, by differential scanning calorimetry and optical microscopy. Experimental results indicate that PBSU is miscible with PEO as shown by the existence of single composition dependent glass transition temperature over the entire composition range. In addition, the polymer-polymer interaction parameter, obtained from the melting depression of the high-T_m component PBSU using the Flory-Huggins equation, is composition dependent, and its value is always negative. This indicates that PBSU/PEO blends are thermodynamically miscible in the melt. The morphological study of the isothermal crystallization at 95 °C (where only PBSU crystallized) showed the similar crystallization behavior as in amorphous/crystalline blends. Much more attention has been paid to the crystallization and morphology of the low-T_m component PEO, which was studied through both one-step and two-step crystallization. It was found that the crystallization of PEO was affected clearly by the presence of the crystals of PBSU formed through different crystallization processes. The two components crystallized sequentially not simultaneously when the blends were quenched from the melt directly to 50 °C (one-step crystallization), and the PEO spherulites crystallized within the matrix of the crystals of the preexisted PBSU phase. Crystallization at 95 °C followed by quenching to 50 °C (two-step crystallization) also showed the similar crystallization behavior as in one-step crystallization. However, the radial growth rate of the PEO spherulites was reduced significantly in two-step crystallization than in one-step crystallization.     

Liquid-liquid phase separation in a polyethylene blend monitored by crystallization kinetics and crystal-decorated phase morphologies

A series of polyethylene (PE) blends consisting of a linear high density polyethylene (HDPE) and a linear low density polyethylene (LLDPE) with an octane-chain branch density of 120/1000 carbon was prepared at different concentrations. The two components of this set of blends possessed isorefractive indices, thus, making it difficult to detect their liquid-liquid phase separation via scattering techniques. Above the experimentally observed melting temperature of HDPE, T_m = 133 °C, this series of blends can be considered to be in the liquid state. The LLDPE crystallization temperature was below 50 °C; therefore, above 80 °C and below the melting temperature of HDPE, a series of crystalline-amorphous PE blends could be created. A specifically designed two-step isothermal experimental procedure was utilized to monitor the liquid-liquid phase separation of this set of blends. The first step was to quench the system from temperatures of known miscibility and isothermally anneal them at a temperature higher than the equilibrium melting temperature of the HDPE for the purpose of allowing the phase morphology to develop from liquid-liquid phase separation. The second step was to quench the system to a temperature at which the HDPE could rapidly crystallize. The time for developing 50% of the total crystallinity (t_1/2) was used to monitor the crystallization kinetics. Because phase separation results in HDPE-rich domains where the crystallization rates are increased, this technique provided an experimental measure to identify the binodal curve of the liquid-liquid phase separation for the system indicated by faster t_1/2. The annealing temperature in the first step that exhibits an onset of the decrease in t_1/2 is the temperature of the binodal point for that blend composition. In addition, the HDPE-rich domains crystallized to form spherulites which decorate the phase-separated morphology. Therefore, the crystal dispersion indicates whether the phase separation followed a nucleation-and-growth process or a spinodal decomposition process. These crystal-decorated morphologies enabled the spinodal curve to be experimentally determined for the first time in this set of blends.     

Miscibility and crystallization of poly(ethylene oxide) and poly(ε-caprolactone) blends

Blends of poly(ethylene oxide) (PEO) with poly(ε-caprolactone) (PCL), both semicrystalline polymers, were prepared by co-dissolving the two polyesters in chloroform and casting the mixture. Phase contrast microscopy was used to probe the miscibility of PEOB/PCL blends. Experimental results indicated that PEO was immiscible with PCL because the melt was biphasic. Crystallization of PEO/PCL blends was studied by differential scanning calorimetry and analyzed by the Avrami equation. The crystallization rate of PEO decreased with the increase of PCL in the blends while the crystallization mechanism did not change. In the case of the isothermal crystallization of PCL, the crystallization mechanism did not change, and the change in the crystallization rate was not very big, or almost constant with the addition of PEO, compared with the change of the crystallization rate of PEO.     

Spherulite morphology and crystallization behavior of poly(trimethylene terephthalate)/poly(ether imide) blends

The spherulite morphology and crystallization behavior of poly(trimethylene terephthalate) (PTT)/poly(ether imide) (PEI) blends were investigated with optical microscopy (OM), small-angle light scattering (SALS), and small-angle X-ray scattering (SAXS). Thermal analysis showed that PTT and PEI were miscible in the melt over the entire composition range. The addition of PEI depressed the overall crystallization rate of PTT and affected the texture of spherulites but did not alter the mechanism of crystal growth. When a 50/50 blend was melt-crystallized at 180 °C, the highly birefringent spherulite appeared at the early stage of crystallization (t < 20 min). After longer times, the spherulite of a second form was developed, which exhibited lower birefringence. The SALS results suggested that the observed birefringence change along the radial direction of the spherulite was mainly due to an increase in the orientation fluctuation of the growing crystals as the radius of spherulite increased. The lamellar morphological parameters were evaluated by a one-dimensional correlation function analysis. The amorphous layer thickness showed little dependence on the PEI concentration, indicating that the noncrystallizable PEI component resided primarily in the interfibrillar regions of the growing spherulites.     

Dissipative particle dynamics study on the phase morphologies of the ultrahigh molecular weight polyethylene/polypropylene/poly(ethylene glycol) blends

The dissipative particle dynamics (DPD) simulation method has been used to study mesophase formation of the binary UHMWPE/PP and ternary UHMWPE/PP/PEG blends. The effects of shear rates and volume fractions of each of the blend components on end-to-end distances of UHMWPE, diffusivities and mesoscale morphologies of the blends have been investigated in detail. As compositions of the UHMWPE/PP and UHMWPE/PP/PEG blends vary, the mesoscale simulations have predicted the ordered structures with defined morphologies of lamellas, perforated lamellas, hexagonal spheres, and body-centered-cubic spheres. Micelle-like melted structures between totally disordered and the ordered phases have also been found in the UHMWPE/PP (10/90) blends. Immiscibility property of UHMWPE, PP and PEG induces the phase separation and exhibits different mesoscpic morphologies at different shear rates and volume fractions. Taking the shear rates dependence of mesophase into account, the change in morphology of the UHMWPE/PP/PEG blends with shear rate is also well studied in this work. As a function of PP concentration, the end-to-end distances of UHMWPE are found to decrease with the increase of PP concentration. This effect is more prominent for a high amount of PP.