Blending Sequence Research Articles

Fabrication of electrically conductive microparts by constructing carbon black-rich network under high shear conditions in microinjection molding

Microinjection molding (μIM) is an important technique to fabricate microparts for applications in the fields of automotive and microelectromechanical systems. However, the prevailing high shear conditions in μIM are unfavorable for constructing intact electrically conductive networks because the added fillers tend to be preferentially aligned along the melt flow direction. In this work, a series of polypropylene/polyamide 6/carbon black (PP/PA6/CB) composites with a selective localization of CB in the PA6 phase were used as the model system to prepare electrically conductive microparts. The prevailing high shearing and extensional flow effects in μIM were utilized to deform CB-rich phase with an aim to in situ construct electrically conductive network, thereby improving the electrical conductivity (σ) of subsequent moldings. The results indicated that a higher σ was achieved for PP/PA6/CB microparts when compared with their PP/CB and PA6/CB counterparts, at a lower filler content (<10 wt%). The influence of blending sequence of various components (i.e., PP, PA6, and CB) and annealing treatment on the σ of microparts was also studied. This work provided an approach to the design and preparation of electrically conductive microparts that can be potentially used in high-tech sectors.

Improving the electrical conductivity of multiwalled carbon nanotubes‐containing micromoldings via in situ construction of electrically conductive networks

AbstractMicroinjection molding (μIM) is characterized by high shearing and cooling rates, resulting in higher a degree of filler orientation which impairs the electrical conductivity (σ) of conductive filler‐containing polymer composites when compared with that of compression molding and conventional injection molding processes. In this study, polypropylene/polyamide 6/multiwalled carbon nanotubes (PP/PA6/CNT) composites were used as the model system to investigate how blending sequence, injection speed, and component mass ratios affected the morphology and σ of PP/PA6/CNT microparts. The results demonstrated that CNTs exhibited a higher affinity for the polar PA6 phase and they tended to be preferentially distributed in PA6 domains. The deformation and coalescence of CNT‐rich PA6 phase promoted the creation of an intact and continuous filler network structure along the flow direction under the influence of high shearing conditions in μIM. When the mass ratio of PP:PA6 was 70:30 and the concentration of CNT was 7 wt%, the micropart possessed the highest σ (1.2 × 10−6 S/m) when compared with their PP/CNT (4.4 × 10−9 S/m) and PA6/CNT (3.4 × 10−10 S/m) counterparts. Higher injection speeds resulted in higher degree of CNT orientation, which negatively affected the σ of subsequent moldings. This work established an approach for producing electrically conductive microparts that demonstrate promising applications in the fields of electronics, automotive, and microsystems among others.Highlights PP/PA6/CNT composites were used as model systems for microinjection molding. The electrical conductivity was improved by shear‐induced deformation of CNT‐rich phase. The properties of PP/PA6/CNT microparts were affected by process parameters.

Characterization and in vitro calcium release of the novel calcium-loaded complexes using Antarctic krill protein and pectin: Effect of different blending sequences

Food-grade biopolymer-based complexes are of particular interest in the field of biologic ingredient delivery owing to unique controlled-release properties. Herein, three calcium-loaded complexes using Antarctic krill protein (P) and pectin (HMP) with different blending sequences were designed, named P + Ca + HMP, P + HMP + Ca and HMP + Ca + P, respectively. The calcium-loaded capacity, structural properties, and in vitro gastrointestinal calcium release of the complexes were investigated. The results demonstrated that the calcium binding rate and content of the P + Ca + HMP complex were the highest, reaching to 90.3 % and 39.0 mg/g, respectively. Particularly, the P + Ca + HMP complex exhibited a more stable fruit tree-like structure. Furthermore, the structural analysis confirmed that the primary interaction forces involved hydrogen bond, electrostatic, hydrophobic and ionic bond interaction. Ultimately, the P + Ca + HMP complex demonstrated superior calcium delivery. In conclusion, a novel calcium delivery system was successfully developed based on optimized the self-assembly sequence, which held significant importance in promoting the high-value utilization of Antarctic krill protein and enhancing the in vitro bioaccessibility of calcium.

Bichronous scientific writing course for medical faculty during Covid-19: a SWOT analysis experience

IntroductionWriting and publishing scholarly articles in international peer-reviewed journals can be a challenging undertaking for medical and healthcare professionals in universities, especially in non-English speaking countries. Surprisingly, very few faculty members report receiving guidance on scientific writing. To encourage more faculty engagement in professional development courses aimed at enhancing their writing abilities, we have revamped scientific writing courses to incorporate bichronous (a combination of asynchronous and synchronous) teaching methods.MethodsAfter forming a team, we performed a SWOT (strengths, weaknesses, opportunities, and threats) study of the medical faculty’s present programs and proposed alternatives to prior course issues. In this interventional study, fifty-nine eligible medical educators selected by purposeful sampling underwent a two-and-a-half-month bichronous scientific writing course from March to August 2021. The perspectives of the participants were evaluated through a SWOT analysis. The data were collected through online semi-structured interviews, and data collection continued until data saturation was achieved (40 participants). Data were then coded and analyzed based on conventional qualitative content analysis principles.ResultsOur planned blending sequence and e-feedback increased the medical faculty’s drive to learn, self-confidence, and autonomy while improving their writing skills. Poor ICT and network infrastructure hindered course adoption. Due to the course’s time and the faculty’s own online teaching, many battled with computer vision syndrome, self-discipline, and distractions. Our participants struggled with self-discipline and distractions, so setting a daily time limit may help them concentrate.DiscussionGiven the faculty’s demanding professional lives, this designed course provided a learning opportunity for many that would not have been feasible otherwise.

Effect of blending sequence and epoxy functionalized compatibilizer on barrier and mechanical properties of PBS and PBS/PLA nanocomposite blown films

AbstractThis study focuses on developing compostable nanocomposite blown films, aiming to enhance oxygen barrier properties while maintaining good mechanical performance. Polybutylene succinate (PBS) and its blend with polylactic acid (PLA) were selected as matrices for the films. Organo‐montmorillonite Delite®43B (D43B) clay was incorporated to improve oxygen barrier, and random ethylene‐methyl acrylate‐glycidyl methacrylate terpolymer served as a plasticizer and reactive compatibilizer. Different blending sequences were examined to determine the optimal one that led to significant enhancements in both the barrier and mechanical properties of the final nanocomposite blown film. Various techniques, including SEM, TEM, XRD, DSC, oxygen permeability, and tensile testing were employed to characterize the morphology of the compounds and blown films. The results reveal greater oxygen barrier properties depending on the blending sequence. Indeed, a reduction in oxygen permeability exceeding 50% was observed following the addition of 3 wt% of D43B to the PBS/PLA film, selectively localized in the PLA phase. This enhancement further intensified after the addition of 5 wt% of the epoxy functionalized compatibilizer.Highlights Enhancing PLA‐PBS compatibility with the epoxy functionalized compatibilizer led to a reduction in the final film's oxygen permeability. Achieving ideal ductility and barrier balance in films requires a synergistic blend of components: D43B, PLA, PBS, and compatibilizer. Optimizing balanced synergistic effects among compounds depends on the blending sequence method.

Selective Localization of Nanoparticles to Enhance the Properties of PBS/PLA Nanocomposite Blown Films

The addition of nanoparticles could allow to upgrade the performances of biopolymers, making them fit to replace petroleum-based plastics. In order to maximize the sustainability benefits of bio-nanocomposites, it is fundamental to opportunely tune their bulk properties by acting on their nanostructure. In particular, in nanocomposite blends the final morphologies are highly dependent on the selective localization of the nanoparticles: mainly inside one of the polymeric phases and/or at the interface.In this work, nanocomposite PBS (polybutylene succinate)/PLA (polylactic acid) blown films were prepared with the aim of optimizing their mechanical and gas barrier properties by profiting from the multiple functions of nanofillers as reinforcements, compatibilizers and morphology-directors. PBS/PLA blends, at a constant polymers’ weight proportion (80/20), were prepared by twin-screw extrusion, adding a constant amount of a lamellar nanosilicate (Cloisite 30B), according to different mixing routes: (i) by first dispersing the nanofillers inside the PLA or PBS phase, followed by the compounding with the other resin; (ii) by direct mixing of all the three components.The nanocomposite systems showed a finer dispersion of the PLA phase compared to the neat PBS/PLA blend. While a good exfoliation degree of the nanosilicate was generally observed for all the hybrid samples, the different blending sequence of the nanofillers significantly affected their preferential localization. In particular, the barrier and mechanical performances of the hybrid film PBS/(PLA + C30B) were most positively affected by the selective localization of the nanoplatelets at PBS/PLA interface, since their compatibilizing action was effectively exploited. In fact, this latter sample exhibited an interesting increase (+ 29%) of the deformation at break and a significant improvement (+ 33%) of the oxygen barrier compared with the neat PBS/PLA blend.

Effect of selectively localized layered double hydroxide (LDH) nanosheet on microstructure, toughness, rheological, and crystallization behaviors of PP/EVA/LDH ternary composites

AbstractPolypropylene/ethylene vinyl acetate copolymer/layered double hydroxide (PP/EVA/LDH) ternary composites are fabricated by three different processing methods (Methods I, II, and III). The phase morphology distribution, mechanical toughness, rheological, and crystallization behaviors of PP/EVA/LDH ternary composites are investigated by scanning electron microscopy (SEM), Izod impact test, rheology, differential scanning calorimeter (DSC), and polarizing optical microscope. The theoretical calculation results of the wetting coefficient (ωa) show that LDH nanosheets are preferentially localized in the EVA phase. The cross‐sectional results combined with SEM show that the dispersion and phase morphology distribution of LDH are closely related to the kinetic parameter of the blending sequences. The possible phase distribution mechanism is elucidated accordingly. The II‐6c sample has a highest impact strength (4.8 kJ/m2) under the method II compared with that of PP (2.8 kJ/m2) and PP/EVA (4.1 kJ/m2), which shows a more excellent toughening effect due to the synergy of elasticity of EVA and localization of LDH. The DSC results show III‐6e sample has a highest crystallinity (61.8%) because of more well‐dispersed LDH localized in PP matrix phase, providing more crystallization nucleation sites under method III.

Effect of polymeric ratio in matrix and blending sequence on electrical resistivity of carbon black-filled multi-phase composites

Effect of polymeric ratio in matrix and blending sequence on electrical resistivity of carbon black-filled multi-phase composites

The Effect of the Compounding Procedure on the Morphology and Mechanical Properties of PLA/PBAT-Based Nanocomposites

Abstract Poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT)-based nanocomposites filled with 1 vol.% silicon dioxide nanoparticles (nano-SiO2) were prepared using a co-rotating twin-screw extruder and injection molding. The nanocomposites with various blending sequences were investigated using PLA-based and PBAT-based nanocomposite masterbatches. Morphology of the PLA/PBAT/SiO2 nanocomposites was examined using a scanning electron microscope (SEM) and a focused ion beam (FIB) SEM. It is found that the nano-SiO2 locates in the original polymer phase, in which it is firstly incorporated in the masterbatch process, as well as at the interface between the two polymers. However, as the residence time in the extrusion process increases, the nanoparticles migrate from the original phase to the interface, governed by the thermodynamic driving force. The best optimization of mechanical properties is achieved by using the PBAT-based masterbatches with a one-step process or short residence time. The processing history, therefore, has a tremendous impact on the final properties of the resulting materials.

Formation, structural characterization, stability and in vitro bioaccessibility of 7,8-dihydroxyflavone loaded zein-/sophorolipid composite nanoparticles: effect of sophorolipid under two blending sequences.

Anti-solvent co-precipitation (ASCP) is the most commonly used method of fabricating food-grade nanoparticles, while the impact of the blending sequence on the formation of nanoparticles lacks research. In this study, 7,8-dihydroxyflavone (7,8-DHF) loaded zein-/sophorolipid nanoparticles with two blending sequences (DHF-Z-S and DHF-Z/S) were successfully fabricated by the ASCP method and used to improve the storage stability and the in vitro bioaccessibility of 7,8-DHF. The results showed that blending sequences significantly affect the physicochemical properties of nanoparticles. DHF-Z-S nanoparticles had smaller particle size, lower polydispersity index and turbidity, and higher negative charge, entrapment efficiency and loading capacity compared to DHF-Z/S nanoparticles. Transmission electron microscopy and scanning electron microscopy revealed that DHF-Z-S and DHF-Z/S nanoparticles have core-shell spherical shape at the nanoscale and sophorolipid changed the surface morphology of zein nanoparticles. Fourier transform infrared spectroscopy and fluorescence spectrum analysis confirmed the presence of effective hydrogen bonding, electrostatic interactions and hydrophobic effects between 7,8-DHF, zein and sophorolipid and the presence of stronger hydrogen bonding and hydrophobic effects in DHF-Z-S nanoparticles. The encapsulated 7,8-DHF was in an amorphous state rather than a crystalline form as determined by X-ray diffraction analysis. Circular dichroism revealed that 7,8-DHF and sophorolipid were capable of changing the secondary structure of zein remarkably. More importantly, compared to DHF-Z/S nanoparticles, the DHF-Z-S nanoparticles possessed higher storage stability and in vitro bioaccessibility. Collectively, DHF-Z-S nanoparticles developed in this study might be a promising means of encapsulating, protecting and delivering hydrophobic nutraceuticals for applications in functional foods.

The Influence of Different Compounding Sequence and Peanut Shell Powder Loading on Properties of Polylactic Acid/Thermoplastic Corn Starch Biocomposites

Three different blending sequences were used to prepare the peanut shell powder (PSP)‐filled polylactic acid (PLA)/thermoplastic corn starch (TPCS) biocomposites. The blending sequences can be summarized as (1) S1: PLA was added, followed by TPCS and PSP, (2) S2: PLA was added, followed by PSP and TPCS, and (3) S3: TPCS was added, followed by PLA and PSP. Various loadings of PSP filler were used from 0 to 40 wt%. The correlation between different blending sequences and PSP filler loading of PLA/TPCS biocomposites were discussed in terms of processing torque, tensile properties, surface morphology, and thermal degradation. Results showed that S1 system is the best blending sequence to prepare PLA/TPCS biocomposites compared to S2 and S3 systems. S1 system had established the low stabilization torque, better tensile strength, elongation at break, and thermal stability. Scanning electron microscopy (SEM) analysis of S1 system revealed better adhesion between filler and the matrix. Incorporation of PSP had influenced the properties of PLA/TPCS biocomposites. Increment of PSP loading increased stabilization torque and tensile modulus while decreasing tensile strength, elongation at break, and thermal stability of PLA/TPCS biocomposites. SEM analysis also managed to detect holes and cavities as the filler pulled out on the tensile fractured surface due to poor adhesion between filler and matrix.

Graft ratio: Quantitative measurement and direct evidence for its blending sequence dependence during reactive compatibilization in PVDF/PLLA

The graft ratio during reactive compatibilization plays important roles in determining phase morphology and consequent performance. The quantitative measurement of it remains absent, which does hinder the basic understanding and applications of reactive compatibilization. In this work, co-continuous structures have been fabricated in PVDF/PLLA with reactive comb compatibilizers (RCC). Based on the co-continuous structures, acid hydrolysis has been employed to remove both reacted and free PLLA, producing acid hydrolysis ratio (AR). On the contrary, only free PLLA can be extracted by chloroform (its selective solvent), corresponding to the extraction ratio (ER). The difference between AR and ER represents the reacted weight percent of PLLA, which is a good parameter to describe the graft ratio (GR). According to the quantitative measurement of GR, the direct evidence for the blending sequence dependence of the extent of graft reaction has been provided. By optimizing the migration and localization of compatibilizers, 50 nm co-continuous structures have been fabricated in (PLLA/RCC)/PVDF, in which GR exhibits the highest magnitude. This is the reason for the best mechanical and optical performances in the resultant specimen. Our results open a new avenue for understanding the reactive compatibilization in polymer blend.

Tailoring performance of PP/HIPS/SEBS through blending design

In this work blending design was applied to development of polypropylene (PP)/high impact polystyrene (HIPS) blends using styrene-(ethylene/butylene) styrene (SEBS) as compatibilizing agent. PP/HIPS/SEBS (50/40/10%) which presented the best balance between impact strength and stiffness was selected, aiming to investigate the effect of five blending sequences on morphology, mechanical, thermomechanical and thermal properties. Blends were initially compounded in a corrotational twin screw extruder and later on extruded granules were injection molded. Acquired results showed the morphology and impact of compatible blends were distinct and depend on blending sequence, i.e., being PP and SEBS firstly extrusion premixed followed by HIPS addition in the second extrusion step there was increase in impact strength, thermal deflection temperature (HDT), and thermal stability compared to PP and PP/HIPS, contrary, when HIPS and SEBS were firstly extrusion premixed and PP was added in the second extrusion step excessive reduction of HIPS particle size was verified; and additionally HDT, impact strength and thermal stability decreasing were observed compared to the other sequences. Summing up, PP/HIPS/SEBS properties are adjustable to specific application needs modifying the blending route.

Bionanocomposites of PLA/PBAT/organophilic clay: preparation and characterization

Abstract The objective of this study was to develop bionanocomposites from blends of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) and from 3% and 6% bentonite clay. Initially, the bentonite clay was treated with Praepagen salt, and the properties of the modified clay were evaluated. After the organophilization of the clay was completed, 50:50 blends of PLA/PBAT were prepared, and 3 and 6% clay was added. To test the dispersion of the system, the blending sequence was performed using eight different sequences for the addition of clay to the PLA/PBAT matrices. The mixtures were prepared in a twin screw extruder, and the specimens were subsequently injection molded. The investigated mechanical and morphological properties included the yield strength, yield strain, tensile and bending elastic modulus, and scanning and transmission electron microscopy analyses. The results of this study showed increases of the mechanical properties when nanoparticles were added and the formation of bionanocomposites with intercalated structures.

Effects of blending sequences and molecular structures of the compatibilizers on the morphology and properties of PLLA/ABS blends.

The effects of molecular structures of the compatibilizers and blending sequences on the morphology and properties of the immiscible poly(l-lactide)/acrylonitrile-butadiene-styrene (PLLA/ABS) blend are investigated herein. The comb-like polymers (RC), which are constituted by a poly(methyl methacrylate) (PMMA) backbone and side chains and a few epoxy groups distributed randomly along the backbone, are found to be better compatibilizers for improving the morphology and mechanical properties of the PLLA/ABS blend, compared to linear polymers (RL) constituted by a PMMA backbone and epoxy groups along the backbone. In addition, the blending sequence, which dictates the extent of grafting reaction between carboxyl end groups of PLLA and epoxy groups in the RL and RC compatibilizers, is found to influence the diffusion and location of the in situ formed RL-g-PLLA and RC-g-PLLA polymers in the blend system. By blending RL or RC polymers with ABS phase firstly, the epoxy groups are diluted by ABS phase; thus, during the second step, blending with PLLA phase, lightly grafted polymers are formed. This method is found to be the best sequence to compatibilize the PLLA/ABS system. When the PLLA phase is mixed with the compatibilizers firstly, the highly grafted polymers are prone to be trapped in the PLLA phase, because the PMMA segments are shielded by the densely grafted PLLA segments from interacting efficiently with the ABS phase, and thus the morphology and mechanical properties of the blend deteriorate accordingly.

Aspects regarding the efficiency of nanosilica as an interfacial compatibilizer of a polypropylene/ethylene vinyl-acetate immiscible blend

The effects of blending sequence and residence time on the efficiency of nanosilica as an interfacial compatibilizer of an immiscible blend of polypropylene and ethylene vinyl-acetate (PP/EVA) with unstable droplet-matrix morphology, melt-compounded in a twin-screw extruder, was investigated. Morphological analysis revealed that the nanosilica particles are adsorbed at the blend interface, irrespective of the processing conditions adopted, which is in good agreement with predictions based on the thermodynamic interactions, kinetics of mixing and rheological parameters. It was observed that the effectiveness of interfacial nanosilica in the compatibilization of the PP/EVA blend is greatly dependent on the mixing time, and the blending sequence is less important. The size of the EVA droplets is reduced when PP/EVA blends are processed with longer residence times, and increases with shorter mixing times. The results reported herein and in a previous publication [Polym Test 34 (2014) 175–182] suggest that the interfacial nanosilica layer does, in fact, inhibit the coalescence while at the same time hindering the break-up of EVA droplets during the PP/EVA melt blending, with the net effect being dependent on the magnitude of these two time-related mechanisms.

Characterization of curcumin loaded gliadin-lecithin composite nanoparticles fabricated by antisolvent precipitation in different blending sequences

Abstract Anti-solvent precipitation is a most commonly means of fabricating food-grade nanoparticles, while the impact of the blending sequence on the formation of nanoparticles is still unclear. In this study, curcumin (Cur) loaded nanoparticles were fabricated by antisolvent precipitation method using gliadin and lecithin in different blending sequences. Compared to stepwise antisolvent precipitation (SASP), antisolvent coprecipitation (ASCP) was capable of improving delivery efficiency with smaller particle size, lower turbidity and higher encapsulation efficiency of Cur. Based on the results of zeta-potential and turbidity, ASCP exhibited the greater capability to allocate lecithin on the particle surface than SASP, which potentially resulted in the smoother surface of gliadin-lecithin-Cur nanoparticles in morphological observation. The Cur entrapped in the nanoparticles was confirmed by fluorescence spectrum analysis. The results from particle size, Fourier transform infrared and circular dichroism analysis revealed that Cur was interacted with gliadin and lecithin mainly through hydrogen bonding, electrostatic interaction and hydrophobic effects, and interpreted that ASCP was capable of remarkably changing the secondary structure of gliadin, which was beneficial for reduction of the particle size. An alternative advantage of ASCP was to protect Cur in the nanoparticles against UV irradiation and thermal treatment with higher antioxidant capacity than SASP. Therefore, ASCP possessed wide applications in delivering bioactive compounds and the blending sequence played an important role on the performance of delivery systems.

Creative Virtual Tree Modeling Through Hierarchical Topology-Preserving Blending.

We present a new method to efficiently generate a set of morphologically diverse and inspiring virtual trees through hierarchical topology-preserving blending, aiming to facilitate designers' creativity production. By maintaining the topological consistency of the tree branches, sequences of similar yet different trees and novel intermediate trees with encouragingly interesting structures are generated by performing inner-species and cross-species blending, respectively. Hierarchical fuzzy correspondences are automatically established between two or multiple trees based on the multi-scale topology tree representations. Fundamental blending tasks includingmorph, grow andwilt are introduced and organized into a tree-structured blending scheduler, which not only introduces the randomness into the blending procedure but also wisely schedules the tasks to generate topology-aware blending sequences, contributing to a variety of resulting trees that exhibit diversities in both geometry and topology. Most significantly, multiple batches of blending can be executed in parallel, resulting in a rapid creation of a large repository of diverse trees.

The Effect of Blending Sequence on Nanoclay Partitioning and Microfibrillar Morphology in Blend Nanocomposite Fibers

ABSTRACTThe aim of this article was to provide an insight into the effect of nanoclay partitioning on the droplet deformation and fibril formation in melt-compounded polypropylene/poly (butylene terephthalate)/organoclay blend nanocomposite fibers prepared by different blending sequences. An attempt was also made to investigate the effect of compatibilizer on the partitioning of nanoclay in these blend systems. Melt viscoelastic behavior, wide angle X-ray diffraction and transmission electron microscopy, along with scanning electron microscopy, revealed that the localization of nanoclay in the poly (butylene terephthalate) dispersed phase reduced the droplet deformation and fibril formation. It was demonstrated that the best microstructure of the blend nanocomposites for the fibrillation process was to have the maximum percentage of exfoliated nanoclay in both polymeric phases. Incorporation of compatibilizer can develop the microfibrillar morphology due to its assisting role in transferring a higher fraction of nanoclay platelets from droplets into the matrix and also increasing the extent of melt intercalation in the matrix.

Tailoring morphology to improve the gas-barrier properties of thermoplastic polyurethane/ethylene-vinyl alcohol blends

The morphology and helium-barrier properties of thermoplastic polyurethane (TPU)/ethylene-vinyl alcohol (EVOH) blends with and without dicumyl peroxide (DCP) were investigated by melting blending. A lamellar dispersion of EVOH with good helium-barrier properties was observed in the TPU matrix with DCP. The evolution of the morphology of the blends is mainly related to the variation of the viscosity ratio between the dispersed phase and the matrix phase. Compared with pure TPU, lamellar morphology increased the helium-barrier properties of the TPU/EVOH (60/40) blend by as much as 10-fold. We also explored the effects of composition, DCP content, and blending sequence on the morphology and helium-barrier properties of the TPU/EVOH blends. The morphology of the blends ranged from a droplet-matrix to a lamellar structure. We determined the optimum amount of DCP to improve the helium barrier of the blends. The helium-barrier properties of the blends prepared by direct blending were superior to those of the blends prepared by two-segment blending, and the blends prepared by direct blending exhibited a well-developed lamellar morphology. We compared the permeability of the samples with the theoretical results to explain the relationship between morphology and helium-barrier properties. POLYM. ENG. SCI., 56:922–931, 2016. © 2016 Society of Plastics Engineers