Morphology Of Dispersed Phase Research Articles

Development of toughened and heat-resistant biodegradable injection-molded polylactide acid-based blend foams via enhancing interfacial bonding and PLA phase crystallization

Polylactic acid (PLA) foam is gaining increased attention as a biodegradable alternative to traditional petroleum-based plastic foams, which pose significant environmental pollution issues post-use. However, its potential application is greatly limited by inherent shortcomings such as brittleness and diminished heat resistance post-melting. Herein, high-performance biodegradable PLA/poly(butylene succinate) (PBS) blend foams with well-defined cell structure, high ductility, and enhanced heat resistance were fabricated using a core-back foam injection molding (FIM) process coupled with a straightforward annealing procedure. To enhance compatibility and tailor the dispersed phase morphology into a more fibrillar structure, an epoxy-functional chain extender (ADR) was incorporated. This addition resulted in a substantial increase in the notched impact strength, elevating it to 7.0 kJ/m2, compared to the mere 1.5 kJ/m2 of unmodified PLA foam. Moreover, with the inclusion of 1.0 phr ADR, the notched impact strength of the foam post-annealing soared to 20.7 kJ/m2, a 13.8-fold enhancement compared to pure PLA foam. The formation of a uniformly distributed and interlocked “shish-kebab" crystal structure in the blend facilitated effective stress transfer and distribution, leading to shear yield in the PLA matrix. Additionally, the heat deflection temperature of the annealed blend foam showed a significant increase significantly to 94.7 °C, in contrast to the mere 55.6 °C of pure PLA foam. This study demonstrates a viable and feasible strategy for preparing fully biodegradable PLA foams with high-toughness and heat resistance.

Ternary Blends from Biological Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), Poly(propylene carbonate) and Poly(vinyl acetate) with Balanced Properties.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) has gained significant attention because of its biodegradability and sustainability. However, its expanded application in some fields is limited by the brittleness and low melt viscoelasticity. In this work, poly(vinyl acetate) (PVAc) was introduced into PHBH/poly(propylene carbonate) (PPC) blends via melt compounding with the aim of obtaining a good balance of properties. Dynamic mechanical analysis results suggested that PPC and PHBH were immiscible. PVAc was miscible with both a PHBH matrix and PPC phase, while it showed better miscibility with PHBH than with PPC. Therefore, PVAc was selectively localized in a PHBH matrix, reducing interfacial tension and refining dispersed phase morphology. The crystallization rate of PHBH slowed down, and the degree of crystallinity decreased with the introduction of PPC and PVAc. Moreover, the PVAc phase significantly improved the melt viscoelasticity of ternary blends. The most interesting result was that the remarkable enhancement of toughness for PHBH/PPC blends was obtained by adding PVAc without sacrificing the strength markedly. Compared with the PHBH/PPC blend, the elongation at the break and yield strength of the PHBH/PPC/10PVAc blend increased by 1145% and 7.9%, respectively. The combination of high melt viscoelasticity, toughness and strength is important for the promotion of the practical application of biological PHBH.

Direct numerical simulations of liquid–liquid dispersions in a SMX mixer under different inlet conditions

The internal dynamics of static mixers handling liquid–liquid flows have been comprehensively explored over the past decade. Although the effect of the inlet configuration is often overlooked, a few studies have suggested a relationship between the phases’ initial set-up and the performance of the mixer in terms of the droplet size distribution (DSD). Accordingly, different dispersed phase morphologies at the inlet of a SMX static mixer have been tested and their effect on the overall dispersion performance of the mixer has been evaluated based on the DSD and growth of interfacial area. In particular, three representative scenarios are considered: (1) Isolated cases, where one and three individual droplets are injected, mimicking a controlled syringe injection; (2) Numerous variable-sized droplets, simulating a pre-mixed/dispersed inlet; and (3) Jet inlet, emulating a standard phase injection from a gear pump. In addition, this study provides novel insight into the underlying physics dictating droplet deformation and breakage in SMX mixers for industrially-relevant scenarios. This can be achieved thanks to the massively-parallel high-fidelity three-dimensional direct numerical simulations computed with a robust hybrid front-tracking/level-set algorithm, which provides a wealth of information on intricate interfacial dynamics; this information cannot be obtained via experimental or volume-averaged modelling techniques implemented in past studies.

Fabrication of Biodegradable Poly(Lactic Acid) Composites with High Toughness via In Situ Fibrillation Method and Facile Annealing Process

Elastomer-toughened biodegradable poly(lactic acid) (PLA) composites have been extensively studied; however, improving the toughening efficiency of elastomers with low costs while maintaining the biodegradability of composites remains challenging. In this work, biodegradable PLA/poly(propylene carbonate) polyurethane (PLA/PPCU) composites with high toughness were successfully prepared by the in situ fibrillation method followed by a facile annealing treatment. The chain extender (CE) was added to alter the viscosity ratio of the dispersed phase to the matrix, thereby tailoring dispersed phase morphology. PPCU fibers were observed when the CE content is greater than 0.5 wt %. Due to the increase in interfacial area, the impact strength increased from 5.1 ± 1.1 kJ/m2 for PLA/PPCU/CE blends with droplet-like dispersed phase morphology to 8.3 ± 1.0 kJ/m2 for PLA/PPCU/CE blends with fibrous dispersed phase morphology. Furthermore, when the CE content was 1.5 wt %, the impact strength of PLA/PPCU/CE blends increased sharply to 30.5 ± 3.9 kJ/m2 after a facile annealing treatment, which could be attributed to the greatly increased interfacial area and interfacial strength. This work provides a viable way to improve the toughness of PLA-based blends without sacrificing their degradability, which will facilitate the large-scale practical application of PLA.

Modification of reactive PB‐g‐SAG core–shell particles to achieve higher toughening ability for brittle polylactide

AbstractCore–shell structured particles have been used to toughen brittle polylactide (PLA) extensively. In this research, reactive core–shell (RCS) particles with polybutadiene (PB) as core and the terpolymer styrene–acrylonitrile‐glycidyl methacrylate as shell were prepared to improve the toughening ability of RCS for PLA. The tert‐dodecyl mercaptan (TDDM) content was varied during polymerization and higher TDDM concentrations induced lower grafting and cross‐linking of the PB phase, which significantly influenced the dispersed phase morphology and toughness of RCS toughened PLA blends. With the increase of TDDM content, the phase morphology of RCS changed from uniform dispersion, net‐like structure to an agglomeration pattern. The impact strength of PLA blends increased with TDDM content and reached 922 J/m for the PLA/RCS‐T5 (TDDM: 1.18 wt%), which was 30 times higher than pristine PLA and ~3 times than PLA/RCS‐T0 blend. Higher TDDM contents decreased toughening efficiency. Appropriate TDDM contents decreased the glass transition temperature (Tg) and cross‐linking degree of RCS particles which enhanced the cavitation ability of the PB core phase and promoted the shear yielding of PLA matrix. The modification effect of TDDM solves the problem of insufficient toughening ability of core–shell particles. Under the same toughener content, the modified RCS particles make the PLA blend achieve super toughness.

Comfort fitting shape memory elastomer with constructed strong interface based on amphiphilic hybrid Janus particles

Comfort fitting shape memory elastomer exhibits various potential application in flexible wearable and biomedical devices, which can be developed by mixing the comfort fitting elastomer with the materials of reversible transition. However, it's very difficult to obtain the soft touching feeling, high elongation, and excellent shape memory property at the same time, and the key point mainly depends on improving interface stability and adjusting the morphology by the compatibilizer . In the work, silicone elastomer with excellent shape memory property was obtained by developing an amphiphilic PCL-JP-PDMS hybrid Janus particles compatibilizer for methyl vinyl silicone elastomer/polycaprolactone (MVQ/PCL) blend. Only through increasing the PDMS grafting ratio on the PCL-JP-PDMS particles compatibilizer, the morphology of PCL dispersed phase changed from short fibrous to similar spherical, which ensured the comfort feeling (E = 5.9 MPa), high fixity (R f = 95%) and recovery ratio (R r = 99%) of shape memory MVQ/PCL blends. Furthermore, the shape memory silicone elastomer exhibited impressive elasticity in temporary shape at T = 25 °C, which is quite suitable for designing wearable device. Silicone elastomer with excellent shape memory property was obtained by developing an amphiphilic PCL-JP-PDMS hybrid Janus particles compatibilizer for MVQ/PCL blend, the amphiphilic PCL-JP-PDMS Janus particles were anchored at the interface of MVQ/PCL blends by the similar molecular chain entanglement and the stable conformation of asymmetric SiO 2 @PDVB particles. Much more importantly, the PCL-JP-PDMS particles with different PDMS grafting ratio were prepared as the compatibilizer, which made the interface adhesion and the property of MVQ/PCL blend be regulated by PDMS grafting ratio, which ensured the comfort feeling (E = 5.9 MPa), high fixity (R f = 95%) and recovery ratio (R r = 99%) of shape memory MVQ/PCL blends under the content of 3 wt % particles and 30 wt % PCL. Furthermore, the shape memory silicone elastomer exhibited impressive elasticity in temporary shape at T = 25 °C, which is quite suitable for designing wearable device.

Impact of hybrid nanofillers on the structure and property of polypropylene/polystyrene composites based on elongation flow

AbstractThe composites comprised of polypropylene (PP), polystyrene (PS) and hybrid nanofillers were prepared by a novel eccentric rotor extruder based on elongation flow. The morphology, thermal behavior and rheological properties were investigated. The morphology of the PS dispersed phase changed from circular shape of PP70/PS30 blend to microfiber shape of PP/PS/MWCNTs/MMT composite with an increase of the number of the hybrid nanofillers dimensions. The nano‐TiO2 and MWCNTs were mainly located at the interface, did not change the shape of the PS dispersed phase but reduce the size of the dispersed phase. The hybrid nanofillers containing MWCNTs had better modification effect on the improvement of the crystalline ability of PP compared with the hybrid nanofillers without MWCNTs. The introduction of the hybrid nanofillers did not affect the crystal type of PP, but influence the perfection of crystallization of PP. The hybrid nanofillers had a nice enhancement on the thermal stability of the PP/PS blend. Compared with PP, the low frequency G′ of the hybrid nanofillers filled PP70/PS30 composites increased by two orders of magnitude. With an increase of the dimensionality of the hybrid nanofillers, the restriction of the molecular chains relaxation caused by the hybrid nanofillers was enhanced.

Effect of dispersion and orientation of dispersed phase on mechanical and electrical conductivity

AbstractMelt mixed polypropylene/polyamide 6 (PA6) and multiwalled carbon nanotubes (CNTs) were molded by compression, injection, and interval injection molding. PA phase exists as an isolated dispersed phase in the sea–island system with different phase orientations and dispersion degrees. CNTs prefer to be located in the minor PA phase because of their remarkable compatibility. However, when the content of CNTs is high enough, a conductive path can be formed regardless of the phase morphology. Moreover, when the CNT content is low, the dispersed PA forms an unelongated structure, which is beneficial to electrical conductivity. Although the elongated PA phase holds advantages in terms of its tensile properties, its conductivity network is defective. These results were proposed to uncover the influence of dispersed phase morphology on mechanical and electrical conductivity.

Preparation and characterization of PLA/PBAT/CNC blend nanocomposites

In this study, the effect of cellulose nanocrystals (CNCs) on the properties of polylactide (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends was investigated. Samples were prepared via (i) solution casting (SC) and (ii) combination of solution casting and melt mixing through twin-screw extruder (mTSE). Scanning electron microscopy images revealed the effect of CNC content on the droplet morphology of PBAT dispersed phase. Rheological analysis showed that 3 wt% of CNC formed a strong network in PLA by SC method. Differential scanning calorimetry results depicted the heterogeneous nucleation effect of CNC on PLA’s crystallization in samples prepared by mTSE. Dynamic mechanical analysis illustrated that CNC enhanced the modulus beyond the glass transition temperature of PLA regardless of the preparation method. The tensile and impact properties also elucidated that the existence of any possible residual solvent in blends could dramatically avoid achievement of improvements in ductility and impact properties.

Preparation of stiffer ternary blends of polypropylene/polyamide 6/biodegradable polymers with improved interfacial adhesion

AbstractBlends of polypropylene (PP), polyamide 6 (PA6), and biodegradable polymers (BPs) such as poly(D,L‐lactic acid) (PDLLA), poly(lactic acid‐co‐ε‐caprolactone) (poly[LA‐co‐ε‐CL]) and poly(ε‐caprolactone) (PCL) were prepared using a twin‐screw mini‐extruder. The composition of the blend PP/PA6 was fixed at a mass proportion of 70/30, and the compatibilized blends contain 5 wt% of each BP. The morphology observed through scanning electronic microscopy, the dynamic mechanical thermal properties (DMTA), and the biodegradation test after composting and performing optical microscopy (OM) of the blends were investigated. The blend PP/PA6 compatibilized with polypropylene grafted with maleic anhydride (PPMA) was also obtained and used as a reference. The results showed that the PP/PA6/PPMA revealed a more homogeneous morphology and resulted in higher modulus; nevertheless, the sample obtained with the lower molar mass PDLLA as an alternative for PPMA showed a storage modulus behavior close to the reference material. Poly(LA‐co‐ε‐CL) and PCL also showed changes in the morphology of the PA6 dispersed phase. Positive results were observed in the biodegradation test examined by OM for all samples containing BPs. The novelty of this work was to employ BPs as compatibilizing agents of the blends comprising PP/PA6, producing ternary blends with superior mechanical properties due to the better dispersion of the phases.

Predicting the Young's modulus and the impact strength of immiscible polyolefin blends

This paper focuses on the prediction of Young's modulus and impact strength of immiscible polyethylene/polypropylene blends, prepared in the melt, on the whole composition range, starting from the composition, interfacial tension, rheological properties and processing conditions. For this, the model proposed by Veenstra and a tentative model relating respectively the modulus and the impact strength to the composition were used. They were combined with a micro-rheological model developed previously to predict the limits of dispersed phase and co-continuous morphologies, and the characteristic sizes of the phase. The predictions were compared with experimental data for blends of isotactic and syndiotactic polypropylenes and low- and high-density polyethylenes originating from different polymerization process, especially regarding the catalyst systems. The effect of the catalyst systems and the type of morphology on the properties were analyzed, showing better properties for blends of metallocene polyolefins in comparison to those obtained using Ziegler-Natta catalysts.

Processing and characterization of polypropylene (PP)/ethylene–vinyl acetate (EVA) blend-based glassy carbon (GC) composites

Polypropylene (PP)/ethylene–vinyl acetate (EVA) (60/40) blends-based glassy carbon (GC) composites with different contents of GC (0.1 to 5 wt%) were melting processed in a twin-screw extruder and the thermal, mechanical, electrical and morphological properties were evaluated to verify the effectiveness of the addition of GC as filler. Moreover, the effect of the addition of maleic anhydride grafted polypropylene (PP-g-MA) as a compatibilizer agent was also verified. The composites presented dispersed phase morphology with preferential localization of GC on interfacial regions and into the EVA phase. The mechanical properties were improved with the addition of PP-g-MA as a compatibilizer agent for the blend and the addition of GC had little influence on these properties. The results obtained from thermal properties revealed that the GC contributes to the increase in the degree of crystallinity and thermal stability of the composites. The addition of 0.1 wt% of GC increased the elastic modulus and the ultimate tensile strength without loss in the impact strength when compared to the compatibilized blend. The addition of GC increases a decade of magnitude in the electrical conductivity of the PP/EVA blends.

New Thermoplastic Vulcanizate Based on Acetoacetoxy Functionalized Natural Rubber/Polyamide12 Blend Filled with Carbon Black

Thermoplastic vulcanizates (TPVs) based on blends of natural rubber (NR) grafted with poly(acetoacetoxyethyl methacrylate), NR-g-PAAEM, and polyamide12 (PA12) were prepared by the dynamic vulcanization technique. NR-g-PAAEM was first prepared and its surface free energy was evaluated by means of contact angles. Blends of NR-g-PAAEM and PA12 were then prepared at a 60/40 blend ratio (wt%) using a dynamic vulcanization technique. The results revealed that TPVs exhibited a dispersed-phase morphology. However, the TPVs filled with carbon black (CB) showed much smaller dispersed rubber particles when compared to the unfilled TPV. TEM analysis also revealed that the CB appeared to be mainly located within the NR-g-PAAEM phase. The presence of CB generally raised the melt viscosity and increased shear during melt-mixing, resulting in finer dispersion of the rubber particles. Additionally, a significant enhancement in the tensile properties of the TPV was also achieved by the incorporation of CB. The optimum tensile properties were attained by the addition 30 phr of CB. The results also showed that the incorporation of CB into the NR-g-PAAEM/PA12 TPVs improved their stress relaxation properties. Moreover, the effects of reprocessing on the mechanical properties of the TPV filled with CB were also investigated. Although the TPV filled with CB exhibited reprocessing capability, reprocessing at high temperature and shear forces was found to negatively affect its tensile properties, especially after the third reprocessing cycle.

Effect of Poly(styrene-ran-methyl acrylate) Inclusion on the Compatibility of Polylactide/Polystyrene-b-Polybutadiene-b-Polystyrene Blends Characterized by Morphological, Thermal, Rheological, and Mechanical Measurements.

A poly(styrene-ran-methyl acrylate) (S-MA) (75/25 mol/mol), synthesized by surfactant-free emulsion copolymerization, was used as a compatibilizer for polystyrene-b-polybutadiene-b-polystyrene (SBS)-toughened polylactide (PLA) blends. Upon compatibilization, the blends exhibited a refined dispersed-phase morphology, a decreased crystallinity with an increase in their amorphous interphase, improved thermal stability possibly from the thicker, stronger interfaces insusceptible to thermal energy, a convergence of the maximum decomposition-rate temperatures, enhanced magnitude of complex viscosity, dynamic storage and loss moduli, a reduced ramification degree in the high-frequency terminal region of the Han plot, and an increased semicircle radius in the Cole–Cole plot due to the prolonged chain segmental relaxation times from increases in the thickness and chain entanglement degree of the interphase. When increasing the S-MA content from 0 to 3.0 wt %, the tensile properties of the blends improved considerably until 1.0 wt %, above which they then increased insignificantly, whereas the impact strength was maximized at an optimum S-MA content of ~1.0 wt %, hypothetically due to balanced effects of the medium-size SBS particles on the stabilization of preexisting crazes and the initiation of new crazes in the PLA matrix. These observations confirm that S-MA, a random copolymer first synthesized in our laboratory, acted as an effective compatibilizer for the PLA/SBS blends.

Formation of high-density polyethylene–poly(ethylene-octene) core–shell particles in recycled poly(ethylene terephthalate) by reactive blending

Recycled poly(ethylene terephthalate) (R-PET)/high-density polyethylene (HDPE)/glycidyl methacrylate grafted poly(ethylene-octene) (mPOE) blends, in which the binary (HDPE/mPOE) dispersed phase was of a HDPE core-mPOE shell structure, were prepared. For this purpose, HDPE-g-mPOE graft copolymers were prepared in HDPE/mPOE blends via reactive extrusion with the presence of the free radical initiator dicumyl peroxide (DCP). Then, R-PET was blended with the HDPE/mPOE blends by melt extrusion. The effect of the DCP and mPOE content in the HDPE/mPOE blends on the phase morphology and mechanical properties of the R-PET/HDPE/mPOE blends were studied systematically. It was found that the blends containing reactive compatibilizer exhibited the encapsulation of the HDPE by the mPOE, forming core–shell particles dispersed phase morphology. The graft chains of HDPE-g-mPOE-g-PET formed by the in situ reaction between R-PET and mPOE phases reduced the interfacial tension. Consequently, the dispersed phase morphology was observed to form smaller diameter core–shell particles. The resultant blends exhibited an effect on both the thermal and mechanical properties. Differential scanning calorimetric analysis showed the dispersed phase particles could act as a nucleating agent in the R-PET matrix to improve the crystallization temperature, while the graft copolymers formed in the compatibilized R-PET/HDPE/mPOE blend decreased the nucleation activity. Notched Charpy impact strength and elongation at break of the R-PET were improved by forming the core–shell particles dispersed phase morphology.

Study of the phase morphology and toughness in poly (vinyl chloride)/acrylonitrile–styrene‐acrylic/styrene–butadiene–styrene ternary blends influenced by interfacial/surface tension

ABSTRACTThe effect of interfacial interaction on the phase morphology and toughness of poly (vinyl chloride) (PVC)/acrylonitrile–styrene‐acrylic (ASA) terpolymer/styrene–butadiene–styrene (SBS) block copolymer ternary blends has been investigated. Water and diiodomethane liquids were used for static contact angle measurements to get surface tension and calculate interfacial tension. A dispersed phase morphology of ASA and SBS in the PVC matrix was predicted by the spreading coefficient theory, which was calculated through interfacial tensions between different polymer pairs. Extraction experiment and scanning electron microscopy were combined to verify this morphology. When the volume fraction of SBS was small, SBS was dispersed in the matrix as droplets and the strong PVC/styrene–acrylonitrile interfacial interaction made up for the poor interfacial adhesion between SBS and PVC. Herein, SBS showed an effective toughening effect on PVC/ASA blends. With the addition of 2.5‐ and 5‐phr SBS, the blends had the highest impact strength of 88.75 kJ/m2 at 23 °C and 9.98 kJ/m2 at 0 °C, respectively. With the further increase of the SBS content, the diameter of the SBS drops increased largely and the poor interfacial adhesion between SBS and PVC played a leading role, resulting in a sharp decrease in toughness and a sharp ductile–brittle transition. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47721.

Nonisothermal crystallization kinetic studies on melt processed poly(ethylene terephthalate)/polylactic acid blends containing graphene oxide and exfoliated graphite nanoplatelets

ABSTRACTNonisothermal crystallization kinetics of poly(ethylene terephthalate)/polylactic acid (PET/PLA) (90/10 and 75/25 wt %/wt %) blend prepared by a melt mixing process in the presence of graphene oxide (GO) and exfoliated graphite nanoplatelets (xGnP) were investigated. The transmission electron microscope (TEM) results revealed that both the GO and xGnP were not inclined to the PLA phase, and the distribution of GO in the blend matrix was better than that of xGnP. The scanning electron microscope (SEM) results demonstrated that both the fillers showed compatibilizing effect and refined the morphology of PLA dispersed phase. The crystallinity and crystallization behavior of samples were studied by X‐ray diffraction (XRD) and multiple cooling rate Differential scanning calorimetry (DSC), respectively. The results showed that the degree of crystallinity and crystallization rate of PET was reduced by blending with PLA. Inclusion of the fillers to the blend further reduced the crystallinity while the crystallization rate was increased. Analysis based on Hoffman‐Lauritzen theory revealed that, compared to xGnP, the GO as a better nucleating agent could more effectively reduce lamella thickness and surface folding free energy of the nanocomposites. Crystallization kinetic studies by Jeziorny model revealed two levels of primary and secondary crystallization mechanisms for all samples. Moreover, activation energy of crystallization of the GO‐containing nanocomposites was lower than that of xGnP‐based systems. All the theoretical treatment and experimental results confirm that, compared to xGnP, the GO is more suitable filler and has stronger effect on enhancing the crystallization kinetic of the PET/PLA blends. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47569.HIGHLIGHTS Studied crystallization kinetics of PET/PLA blend containing xGnP and GO nanoplatelets Compared the role of xGnP and GO in crystallization kinetics of the system Analyzed the crystallization kinetics of the system by various models Determined the surface folding free energy of the developed systems GO‐based systems exhibited lower crystallization activation energy than that of the xGnP‐based systems

Ultra‐high molecular weight styrenic block copolymer/TPU blends for automotive applications: Influence of various compatibilizers

Thermoplastic elastomers (TPEs) based on new generation ultrahigh molecular weight styrene‐ethylene‐butylene‐styrene (SEBS) and thermoplastic polyurethane (TPU) are developed and characterized especially for automotive applications. Influence of maleic anhydride grafted styrene‐ethylene‐butylene‐styrene (SEBS‐g‐MA) and maleic anhydride grafted ethylene propylene rubber (EPM‐g‐MA) as compatibilizers has been explored and compared on the blends of SEBS/TPU (60:40). The amount of compatibilizers was varied from 0 to 10 phr. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies revealed the dramatic changes from a nonuniform to finer and uniform dispersed phase morphology. This was reflected in various mechanical properties. SEBS‐g‐MA modified blends showed higher tensile strength. EPM‐g‐MA modified blends also displayed considerable improvement. Elongation at break (EB) was doubled for the entire compatibilized blends. Fourier‐transform infrared spectrometry (FTIR) confirmed the chemical changes in the blends brought about by the interactions between blend components and compatibilizers. Both SEBS‐g‐MA and EPM‐g‐MA had more or less similar effects in dynamic mechanical properties of the blends. Additionally, melt rheological studies have also been pursued through a rubber process analyzer (RPA) to get a better insight.

Great toughness reinforcement of isotactic polypropylene/elastomer blends with quasi-cocontinuous phase morphology by traces of β-nucleating agents and carbon nanotubes

Aiming at obtaining the polyolefin blends potentially applied in the field of the super-tough polymer products, in this work, isotactic polypropylene (iPP)/styrene-ethylene-butadiene-styrene block copolymer (SEBS) blends with great impact toughness were successfully fabricated by adding traces of β-nucleating agents (β-NAs) and carbon nanotubes (CNTs). The impact toughness of iPP blends with 30 wt% SEBS was as high as 62.4 kJ/m2, when simultaneously containing 0.1 wt% β-NAs and 0.05 wt% CNTs. Their toughness was about 13.1 kJ/m2 more than iPP blends with 30 wt% SEBS and 0.1 wt% β-NAs, 49.6 kJ/m2 more than iPP blends with 30 wt% SEBS and 0.05 wt% CNTs, and almost 22.3 times of pure iPP. The iPP matrix with abundant self-toughed β-crystals generated by β-NAs, the quasi-cocontiunous morphology of the SEBS dispersed phase as well as some small SEBS droplets induced by CNTs in the iPP matrix, and the good interfacial compatibility between SEBS and the iPP matrix all harmoniously took effect to synergistically enhance the toughness of iPP blends.

Solid-state mechanical properties of PE/PA blends filled with organoclay or compatibilized by a graft co-polymer: A comparative study

The comparative study of solid-state linear and non-linear tensile properties of polyethylene/polyamide (80/20) blend with nodular morphology, compatibilized by a graft-copolymer or filled by nanoclay, was reported. Clay and compatibilizer volume fractions were varied from 0.5 to 2.5% relative to PA. Scanning electron microscopy and transmission electron microscopy were performed to investigate the dispersed phase morphology and the structure of the PA-intercalated clay interphase. For the same fraction of clay or compatibilizer, PA nodules were shown to exhibit the same average diameter, allowing the comparison between the two systems. When adding very small amounts of clay or compatibilizer, the Young's modulus was shown to strongly decrease; however, once the interface was saturated, further addition increased the Young's modulus of filled blends, much more markedly than that of compatibilized blends. The elongation at yield and yield strength were improved by addition of the compatibilizer, whereas addition of nanoclay was shown to have the opposite effect. At last, tensile strength and elongation at break were significantly improved compared to those of the neat blend, for both systems. The differences in mechanical properties between the two systems have been discussed in terms of differences in interphase structure.