Next Article in Journal
Mode I Fatigue of Fibre Reinforced Polymeric Composites: A Review
Previous Article in Journal
Development of a Novel Biobased Polyurethane Resin System for Structural Composites
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Polymers
Volume 14
Issue 21
10.3390/polym14214556
polymers-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Morphology and Properties of Polyolefin Elastomer/Polyamide 6/Poly(lactic Acid) In Situ Special-Shaped Microfibrillar Composites: Influence of Viscosity Ratio

by
Min Shi
1,2,
Lijun Wang
2,
Jing Sun
2,
Wensheng Yang
1,* and
Hui Zhang
1,*
1
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
2
Guizhou Material Industrial Technology Institute, Guiyang 550014, China
*
Authors to whom correspondence should be addressed.
Polymers 2022, 14(21), 4556; https://doi.org/10.3390/polym14214556
Submission received: 14 September 2022 / Revised: 30 September 2022 / Accepted: 3 October 2022 / Published: 27 October 2022
(This article belongs to the Section Polymer Processing and Engineering)
Browse Figures
Versions Notes

Abstract

:
In Situ microfibrillation is an easy and economical processing method, which has drawn wide concern in recent years. In Situ special-shaped microfibrillar composites, which with poly(lactic acid)/polyamide 6 (PA6/PLA) together formed special-shaped microfibrils in polyolefin elastomer (POE) matrix, were successfully prepared by using multistage stretching extrusion technology. Four types of PA6 with different viscosity were utilized to investigate the effect of viscosity ratio of PA6 to PLA on the structure evolution of special-shaped microfibrils and the mechanical properties of POE/(PA6/PLA) composites. The morphological observation showed that the viscosity ratio was closely associated to the size and shape of PA6 and greatly affected the microfibrillar morphology of PLA/PA6. When the viscosity ratio of PA6 to PLA was less than 2.2, the “gourd-skewers-like” structure microfibrils were obtained. When the viscosity ratio of PA6/PLA to 14.2 was further increased, the “trepang” structure microfibrils were dominant. The “gourd skewers” structure microfibrils were favorable to improvement the tensile strength, Young’s modulus, and viscoelastic properties of POE/(PA6/PLA) blends compared to the “trepang” structure microfibrils. In addition, the morphology of microfibrils exhibited a negligible effect on the melting and crystallization temperature and crystallization degree of PLA and POE matrix. This work provides a new strategy for designing the in situ special-shaped microfibrillar composites with improved mechanical properties.

1. Introduction

The conventional composite reinforced by the adding of a reinforcing filler (e.g., glass fiber or carbon filler) is typically an organic-inorganic system [1,2]. The adding of filler can effectively improve the mechanical properties of matrix material, which are increasingly attracting the interest of researchers [3,4,5]. In Situ microfibrillar composites (MFCs) are a type of polymer-polymer composites, in which the dispersed component develop microfibrils in situ and distribute uniformly in the matrix during the blending process [6,7,8,9]. MFCs, providing a potential, economical way of tailoring the properties of the polymer blend’s product according to the desired application, which has been widely concerned in recent years [10,11,12]. Xie et al. [13] prepared the Poly(lactic acid) (PLA)/Poly (butylene succinate) (PBS) MFCs and found that the dispersed phase PBS developed in situ nanofibrillar PBS and dramatically improved the strength, modulus, and ductility of composites compared with pure PLA. This phenomenon was found in many composites systems, such as PLA/polyamide 6 (PA6) composites [14], Polyolefin elastomer (POE)/poly(trimethylene terphthalate) (PTT) composites [15,16], and poly(ethylene terephthalate) (PET)/isotatic polypropylene(iPP) composites [17]. Sun et al. [18] prepared POE/PLA MFCs and found that the POE/PLA composites appeared double yield behavior during the tensile process, which was beneficial to improve the mechanical properties of MFCs.
When the mixed material were fed into the extruder, a series of complex changes will occur [19,20]. Polymers will undergo different morphological changes. The dispersed component may breakup into small droplets under the action of the shear and stretching stresses [21,22]. The interfacial tension will drive dispersed droplets form a spherical shape, while the viscous force will drive the drawing of the droplets. When the viscous force was larger than the interfacila tension, the dispersed droplet deformed, making the dispersed droplets transform from droplets to the final fibril [23,24,25,26]. The formation of in situ fibrils is usually an overall result of continuous deformation, coalescence, elongation, and orientation of dispersed droplets [27,28]. The final morphology of the dispersed phase in the blends greatly affects the physical and mechanical properties of MFCs [29,30,31,32]. There are many factors affecting the final morphology of dispersed phase in the MFCs, which include viscosity ratio [33,34], composition [35,36,37], stretch ratio [38,39,40], and compatibility of components [41,42]. It has been reported that the viscosity ratio (ηd/ηm, where ηd is the viscosity of the dispersed component and ηm is the viscosity of the matrix) of the blend played an important role on the formation of the fibril shape [43,44]. Low viscosity ratio facilitated the formation of smaller and more uniform dispersed phase particles, and then led to a narrow diameter distribution of microfibrils after stretching, which resulted in higher strength and modulus [45,46,47,48]. Zhao et al. [49] employed PP with different melt flow rates (MFRs, 3.6, 5, 19, 36 g per 10 min, 230 °C per 2.16 kg) as the matrix prepared PP/PET MFCs and investigated the effect of PP’s viscosity and the PET concentration on the PET nanofibril formation. They found that a PP with a lower melt flow rate (MFRs) was better for generating a higher aspect ratio and smaller diameter PET nanofibrils. The diameter of fibrils from a higher MFR PP decreased with an increasing PET concentration. Yi et al. [48] prepared the isotactic polypropylene(iPP) and poly (ethylene terephthalate) (PET) MFCs and investigated the effect of the viscosity ratio on the morphology and mechanical properties of iPP/PET microfibrillar blend. They found that the viscosity ratio played an important role in the size of dispersed phase, and subsequently affected the morphology of PET microfibrils during stretching. The appropriate viscosity ratio for improved mechanical properties was about 0.083. Min et al. [50] investigated the relationship between the viscosity ratio and morphology of polyethylene (PE)/polystyrene (PS) blend extrudates, and found that the droplets became undulant fibers when the 0.7 < ηd/ηm < 1.7, while ηd/ηm was greater than 2.2, undeformed droplets are observed. However, the viscosity ratio in these studies was the dispersed component viscosity to the matrix component viscosity. In our previous work, in situ special-shaped microfibrillar composites with PLA and PA6 special-shaped microfibrils in POE matrix were first successfully prepared. How the viscosity ratio between the dispersed component (PLA and PA6) affected morphology evolution of MFCs needs to be investigated in more detail.
Herein, in this study, the PA6/PLA master batch with different PA6 viscosity was chosen as a dispersed phase to prepare the POE-based MFCs through the technology of multistage stretching extrusion. The influence of the viscosity ratio of PA6 to PLA on PA6/PLA special-shaped microfibrillar morphology evolution was examined. In addition, the mechanical, rheological, and crystallization properties affected by the morphology of special-shaped microfibrils were carefully investigated.

2. Experimental

2.1. Materials

POE (ENGAGE 8200) with a density of 0.87 g/cm3 and a melt index of 5.0 g/10 min (190 °C) was purchased from Dow Chemical Company, Knoxville, TN, USA. PLA (4032D) with a L-lactide content of roughly 98% and a density of 1.24 g/cm3 was purchased from Natureworks Company, Plymouth, MN, USA. PA6 with different relative viscosity was purchased from Xinhui meida Nylon Co., Ltd., Jiangmen, China. The physical parameters of POE and PLA were given in Table 1 and the physical parameters of PA6 was given in Table 2.

2.2. Specimen Preparation

First, PLA and PA6 were dried in a vacuum oven at 80 °C and 100 °C, respectively, for 12 h. Then, the PA6/PLA master batches with weight ratios of 1/1 were extruded by the twin-screw extruder (CTE-20, Nanjing Jieya Extruded Equipment Co., China). The screw speed was 200 rpm and the temperatures from the hopper to the exit of the extruder were 225–230 °C. Finally, the POE/(PLA/PA6) composites with the weight ratio of 75/25 were extruded by the multistage stretching extrusion assembly, which contained a twin-screw extruder (SHJ-30, Nanjing Jieya Extruded Equipment Co., China), an extrusion die with an assembly of laminating–multiplying elements (LMEs). The screw speed was 250 rpm and the temperature from the hopper to the exit of the extruder was 50–230 °C. The temperature of LMEs was 230 °C. After the POE/(PLA/PA6) melt flowed from the extruder die, the extrudate was further stretched at rate of 80 rpm to obtain MFCs. The in situ POE/(PA6/PLA) MFCs with different viscosity ratio (the ratio of PA6 viscosity to the PLA viscosity at the same temperature) were coded as MFCs-xx, where xx represented the viscosity ratio of PA6 to PLA.

2.3. Characterization

A field emission scanning electron microscope (SEM, QUANTA FEG 250, FEI Company, USA) was employed to observe the microstructure of the composites. The composite sheets were placed in liquid nitrogen for 2 h, finally the samples were cryogenically fractured along to extrusion direction or perpendicular to extrusion direction. The smooth fractured surfaces can then be taken for SEM observation or the further etching process. For the etching, the fractured surfaces were immersed in hot xylene at 80 °C for 12 h to dissolute POE, after which it was cleaned by ethyl alcohol, and then immersed in dichloromethane (CH2Cl2) at 20 °C for 1 h to dissolute PLA. Note that all etched surfaces were cleaned by using distilled water prior to SEM observation.
Thermal analysis of the samples were studied by DSC (Q10, TA Company, New Castle, DE, USA) under N2 atmosphere. The dynamic scanning was applied at a heating rate of 10 °C/min from 5 °C to 240 °C for MFCs. After holding the sample at a high temperature for 5 min, it was then cooled down to 5 °C at a heating rate of 10 °C/min to analyze the crystallinity behavior.
The crystallinity of PA6 and POE were calculated using the following equation:
X c = Δ H m φ × Δ H m 0 × 100 %
The crystallinity of PLA was calculated using the following equation:
X c = Δ H m − Δ H c φ × Δ H m 0 × 100 %
In Equations (1) and (2), Δ H m and Δ H c were the enthalpies of melt crystallization and cold crystallization, respectively. The Δ H m 0 was the melting enthalpy for 100% crystallinity. The Δ H m 0 values of PA6, PLA, and POE were 230 J/g [51], 93.7 J/g [52], and 205 J/g [53], respectively. The symbol φ represented the mass percentage of the PA6, PLA, or POE in the MFCs.
The dynamic rheological experiments of PLA, PA6, and POE/(PLA/PA6) MFCs were studied by Rotational rheometer (MARS60, USA), using parallel-plate geometry with a diameter of 25 mm. The dynamic viscoelastic properties were determined with frequencies from 0.05 to 100 rad/s at 1% strain amplitude. The measured temperature of PLA and PA6 were fixed at 230 °C, which was the processing temperature. The measured temperature of POE/(PLA/PA6) MFCs was fixed at 130 °C, which was lower than the melting temperature of PLA/PA6. According to ASTM standard D638, tensile tests were made by a universal testing machine (CMT6104, China) with a crosshead speed of 500 mm/min and a gauge length of 25 mm. Specimens for tensile test were cut from the extrusion sheet along or perpendicular to the extrusion direction. The width and the thickness of specimens were measured before tensile test. All measurements were repeated at least five times and the average values were reported.

3. Results and Discussion

3.1. Viscoelastic Behavior of PA6 and PLA

Figure 1 shows the storage modulus(G′), loss modulus(G″), and complex viscosity(η*) of PA6 and PLA and the viscosity ratio of PA6/PLA as a function of frequency. It can be seen that the G′ of PA6 increased with the increasing of viscosity of PA6 at identical frequencies. These results can be attributed to the restriction of the PA6 chain’s mobility, which can improve the capability of storing the deformation energy over extended periods of time (increasing the relaxation time) [14]. The G″ of PA6 increased with the increasing of PA6 viscosity (Figure 1b). This can be attributed to the increasing of energy consumption of PA6 chain’s slippage in unit time [40]. In addition, with the increasing of frequencies, the η* of PA6 and PLA decreased continuously (Figure 1c), implying that the PA6 and PLA were non-Newtonian fluids and all followed the shear thinning behavior [34]. When the frequency was 1, the viscosity ratio of PA6 to PLA was 0.5, 2.2, 5.3, and 14.2. The G′, G″, and η* of PLA was only greater than the PA6-2.0 at identical frequencies and the viscosity ratio of PA6-2.0/PLA was lower than 1.

3.2. Morphology and Microstructure of MFCs

Figure 2 shows the SEM images of POE/(PA6/PLA) in situ MCFs and the PA6/PLA microfibrils after etching the PLA and the quantitative analyses of the PA6 phase after etching the PLA. From Figure 2a–d, it can be seen that, after hot stretching, the dispersed phase (PA6 and PLA) was fully extended into special-shaped structure microfibrils in the POE matrix. As compared with the regular cylinder-shaped microfibrils in the POE/PLA composites [18], the special-shaped microfibrils had an uneven diameter. When the viscosity ratio of PA6/PLA was 0.5, the gourd-skewers-like structure microfibrils were dominance. The gourd-skewers-like microfibrils had many knots with a larger diameter connected by the skewer with smaller diameter. With the viscosity ratio of PA6 to PLA increased, the diameters of knots and the distance between knots all tended to decrease. When the viscosity ratio of PA6 to PLA increased to 5.3, the microfibrillar morphology appeared in “trepang” structure (red dotted circle). Further increasing the viscosity ratio of PA6/PLA to 14.2, the “trepang” structure microfibrils were dominant. The trepang-like microfibrils had a large diameter with many small knots on their surfaces. From Figure 2e–h, it can be seen that when the viscosity ratio of PA6 to PLA was 0.5, the PA6 phase presented short rod-like microfibrils, ellipsoid particle, and spherical particle after etching PLA. With the increasing of PA6 viscosity, spherical particles were dominant and the diameter of ellipsoid particle and spherical particles decreased gradually (red dotted circle). The average diameter of PA6 decreased from 3.47 μm to 1.77 μm and the diameter distribution of PA6 became narrow with the increasing of viscosity of PA6 (Figure 2i–l), revealing that the deformation degree of PA6 phase became lower with the increasing of viscosity of PA6 during the hot stretching.
The evolution mechanism of special-shaped microfibrils was shown in Figure 3. when the PA6/PLA master batches were feed into the twin screw extruder, the particles of PA6/PLA master batches broke up to form droplets under the action of shear stress. Under the action of the shear and stretch stress, the dispersed droplets occurred deformed, making the dispersed transformed from droplets to the final fibril [19,27]. When the viscosity ratio of PA6 to PLA was 0.5, due to the PA6 generated short rod-like microfibrils and ellipsoid particle with a larger diameter during the hot stretching, the gourd-skewers-like microfibrils had knots with larger diameter and length. With the viscosity ratio of PA6 to PLA increasing to 2.2, the diameter and length of knots of the gourd-skewers-like microfibrils decreased due to diameter of the PA6 particles decreased. Further increasing the viscosity ratio of PA6/PLA to 14.2. the microfibrils morphology turned into the “trepang” structure.

3.3. Rheological Characterization

Figure 4 shows the dependence of storage modulus(G′), loss modulus(G″), and complex viscosity (η*) on angular frequency(ω) for in situ POE/(PA6/PLA) MFCs at 130 °C. It was evident that the G′ and G″ of all the specimens increased with increasing angular frequency (Figure 4a,b). At low frequencies, the G′, G″ of POE/(PA6/PLA) blends increased linearly. At high frequencies, the frequency-dependence of G′, G″ was substantially weakened and a small platform appeared due to the frequency’s response difference of PA6/PLA microfibrils physically entangled network. The information of situ microfibrils made effective contributions for not only the elastic behavior, but also the viscous behavior. Sun et al. [18] had the similar conclusion about the research of POE/PLA microfibrillar composites fabricated through multistage stretching extrusion. From Figure 4c, it can be seen that all the specimens exhibited shear thinning behavior, indicating that the in situ POE/(PA6/PLA) blends were non-Newtonian fluids, which was similar to the POE/PTT microfibrillar composites [15]. With the increasing of ω, the η* of POE/(PA6/PLA) blends decreased continuously. This result can be ascribed to the de-entanglement of POE chain and the PA6/PLA microfibril remain highly oriented (PA6/PLA microfibrils were solid-state at 130 °C). In addition, with the increasing of viscosity ratio of PA6 to PLA, the G′, G″ and η* of POE/(PA6/PLA) blends increased firstly and then decreased at the same ω. When the viscosity ratio of PA6 to PLA was 2.2, the viscoelastic properties of POE/(PA6/PLA) blends was maximum, revealing that the “gourd skewers” structure microfibrils with a small diameter and length of knots was favorable to improvement the viscoelastic properties of POE/(PA6/PLA) blends than the “trepang” structure microfibrils. The viscoelastic properties of PA6-3.2 were maximum (Figure 1). On the contrary, the minimum value of viscoelastic properties were obtained at the viscosity ratio of 0.5, which was due to the decreased of PA6-2.0 viscoelastic properties (Figure 1) and the larger diameter of gourd-skewers structure microfibrils.

3.4. Thermal Characterization

Figure 5 shows the DSC curves of in situ POE/(PA6/PLA) MFCs. It can be seen that the peak melting temperature of PLA at about 169 °C and that of PA6 at about 223 °C were not affected by the viscosity ratio of PA6/PLA. In addition, the melting enthalpy of PLA was almost constant, while that of PA6 decreased with increasing the viscosity ratio of PA6/PLA. These results indicated that the morphology of PLA/PA6 microfibrils (“gourd skewers” or “trepang”) had negligible effect on the melting temperature of both PLA and PA6. Due to the poor crystallization kinetics of pure PLA, there was not crystallization behavior during the cooling process (Figure 5d) [54]. However, an obvious cold crystallization peak with the peak temperature of about 100 °C can be seen during the heating cycle, which was used to calculate the crystallization degree of PLA. In addition, the crystallization temperature of PA6 decreased, while that of POE were almost constant with the viscosity ratio of PA6/PLA increased (Figure 5e–f). This result indicated that the morphology of PLA/PA6 microfibrils had negligible effect on the melting temperature of matrix POE. The decreased of crystallization temperature of PA6 can be ascribed to the decreased of the PA6 molecular chain’s the mobility with the increasing viscosity of PA6. Figure 6. shows the crystallization degree of PLA, PA6, and POE in MFCs. It can be seen that the crystallization degree of PLA was 28.0% and POE was 2.2%, respectively, and were hardly affected by the viscosity ratio of PA6/PLA. In addition, the crystallization degree of PA6 decreased with the viscosity of PA6 increasing. These results can be ascribed to the increased of the restrictions effect of crystal nucleus formation with the increasing viscosity of PA6.

3.5. Mechanical Property

Figure 7 shows the stress-strain curves and tensile properties of POE/(PA6/PLA) MFCs along to extrusion direction. It was seen that the stress-strain curve of POE/(PA6/PLA) blends showed typical response of elastomeric materials. With the increasing of viscosity ratio of PA6/PLA, the special-shaped microfibrillar composites appeared multiple-yield behavior during the tensile test. As shown in Figure 7b, the tensile strength of MFCs increased firstly and then decreased with the viscosity ratio of PA6/PLA, which agreed with Young’s modulus of POE/(PA6/PLA) (Figure 7a). When the viscosity ratio of PA6/PLA was 2.2, the POE/(PA6/PLA) MFCs had the highest tensile strength and Young’s modulus. This result revealed that “gourd skewers” with small diameter and length of knots were favorable to improvement the strength and modulus of POE/(PA6/PLA) blends compared to the “trepang” structure microfibrils. In addition, the elongation at break of MFCs decreased firstly and then increased with increasing the viscosity ratio of PA6/PLA. When the viscosity ratio of PA6/PLA was 0.5, the maximum value of elongation at break can be obtained. This result can be ascribed to the large specific surface area of “gourd skewers” was favorable to the transfer of stress.
Figure 8 shows the stress-strain curves and tensile properties of POE/(PA6/PLA) MFCs perpendicular to extrusion direction. It was seen that the stress-strain curve of POE/(PA6/PLA) blends showed typical response of elastomeric materials. The POE/(PA6/PLA) MFCs had the similar stress-strain curves with increasing the viscosity ratio of PA6/PLA. As shown in Figure 8b, the tensile strength and elongation at break of MFCs decreased firstly and then increased with the increase of viscosity ratio of PA6/PLA. When the viscosity ratio of PA6/PLA was 0.5, the tensile strength and elongation at break of POE/(PA6/PLA) MFCs obtained a maximum value. This result can be ascribed to enhance of interfacial adhesion between microfibrils and POE matrix due to the large specific surface area of “gourd skewers”.

4. Conclusions

In this work, the POE/(PA6/PLA) MFCs based on the bends of POE as matrix and PA6/PLA master batches as dispersed phase were successfully fabricated by using multistage stretching extrusion technology. The viscosity ratio of PA6 to PLA plays an important role in the morphology of PA6/PLA microfibrils during stretching. When the viscosity ratio of PA6/PLA was less than 2.2, the “gourd-skewers-like” structure microfibrils were obtained. Further increased the viscosity ratio of PA6/PLA to 14.2, the “trepang” structure microfibrils were obtained. The “gourd skewers” microfibrils with small diameter were favorable to improvement mechanical properties and viscoelastic properties of POE/(PA6/PLA) blends compared to the “trepang” structure microfibrils.

Author Contributions

Conceptualization: H.Z.; data curation: J.S.; formal analysis: M.S., L.W., W.Y. and H.Z.; funding acquisition: H.Z.; investigation: M.S.; methodology: L.W.; project administration: W.Y.; resources: W.Y.; validation: L.W.; writing—original draft: M.S.; writing—review and editing: J.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by [the Multi-level talent program of Guizhou Province] grant number [[2019]5637], [Science and Technology Project of Guizhou Province] grant number [[2020]2Y022; ZK[2021]General(253)] and [Science and Technology Project of Baiyun District] grant number [[2019]20]. The APC was funded by [[2020]2Y022].

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data that supports the findings of this study are available within the article.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Zaghloul, M.M.Y.; Mohamed, Y.S.; El-Gamal, H. Fatigue and tensile behaviors of fiber-reinforced thermosetting composites embedded with nanoparticles. J. Compos. Mater. 2018, 53, 709–718. [Google Scholar] [CrossRef]
  2. Zaghloul, M.M.Y.; Zaghloul, M.Y.M.; Zaghloul, M.M.Y. Experimental and modeling analysis of mechanical-electrical behaviors of polypropylene composites filled with graphite and MWCNT fillers. Polym. Test. 2017, 63, 467–474. [Google Scholar] [CrossRef]
  3. Zaghloul, M.M.Y.M. Mechanical properties of linear low-density polyethylene fire-retarded with melamine polyphosphate. J. Appl. Polym. Sci. 2018, 134, 46770. [Google Scholar] [CrossRef]
  4. Zaghloul, M.M.Y.; Zaghloul, M.M.Y. Influence of flame retardant magnesium hydroxide on the mechanical properties of high density polyethylene composites. J. Reinf. Plast. Compos. 2017, 36, 1802–1816. [Google Scholar] [CrossRef]
  5. Zaghloul, M.Y.M.; Zaghloul, M.M.Y.; Zaghloul, M.M.Y. Developments in polyester composite materials-An in-depth review on natural fibres and nano fillers. Compos. Struct. 2021, 278, 114698. [Google Scholar] [CrossRef]
  6. Sun, X.J.; Yu, Q.; Shen, J.B.; Gao, S.L.; Li, J.; Guo, S.Y. In Situ microfibrillar morphology and properties of polypropyl-ene/polyamide/carbon black composites prepared through multistage stretching extrusion. J. Mater. Sci. 2013, 48, 1214–1224. [Google Scholar] [CrossRef]
  7. Li, Z.; Shi, Y.J.; Sun, C.X.; Zhang, Q.; Fu, Q. In Situ micro and nano fibrillar reinforced elastomer composites based on polypro-pylene(PP)/ olefinic block copolymer (OBC). Compos. Sci. Technol. 2015, 115, 34–42. [Google Scholar] [CrossRef]
  8. Maja, K.; Laurens, D.; Ludwig, C.; Kim, R. Relationship between the processing, structure, and Properties of Microfibrillar Composites. Adv. Mater. 2020, 32, 2003938. [Google Scholar]
  9. Mi, D.; Wang, Y.X.; Kuzmanovic, M.; Laurens, D.; Jiang, Y.X.; Cardon, L.; Zhang, J.; Ragaert, K. Effect of phase Morphology on Mechanical Prop-erties: Oriented/Unoriented PP Crystal Combination with Spherical/Microfibrillar PET Phase. Polymers 2019, 11, 248. [Google Scholar] [CrossRef] [Green Version]
  10. Jayanarayanan, K.; Thomas, S.; Joseph, K. Morphology, static and dynamic mechanical properties of in situ microfibrillar composites based on polypropylene/poly (ethylene terephthalate) blends. Compos. Part A Appl. Sci. Manuf. 2008, 39, 164–175. [Google Scholar] [CrossRef]
  11. Rizvi, A.; Park, C.B.P.; Favis, B.D. Tuning viscoelastic and crystallization properties of polypropylene containing in-situ gen-erated high aspect ratio polyethylene terephthalate fibrils. Polymer 2015, 68, 83–91. [Google Scholar] [CrossRef]
  12. Wang, J.F.; Zhang, X.L.; Zhao, T.; Shen, L.Y.; Wu, H.; Guo, S.Y. Morphologies and properties of polycarbonate/polyethylene in situ microfibrillar composites prepared through multistage stretching extrusion. J. Appl. Polym. Sci. 2014, 131, 40108–40115. [Google Scholar]
  13. Xie, L.; Xu, H.; Niu, B.; Ji, X.; Chen, J.; Li, Z.M.; Hsiao, B.S.; Zhong, G.-J. Unprecedented Access to Strong and Ductile Poly(lactic acid) by Introducing In Situ Nanofifibrillar Poly(butylene succinate) for Green Packaging. Biomacromolecules 2014, 15, 4054–4064. [Google Scholar] [CrossRef]
  14. Kakroodi, A.R.; Kazemi, Y.; Ding, W.D.; Ameli, A.; Park, C. Poly(lactic acid)-Based in situ microfibrillar composites with en-hanced crystallization kinetics, mechanical properties, rheological behavior, and foaming ability. Biomacromolecules 2015, 16, 3925–3935. [Google Scholar] [CrossRef] [PubMed]
  15. Wei, L.; Dong, J.; Qi, Y.; Sun, J.; Qin, S. In Situ polyolefin elastomer/poly(trimethylene terephthalate) microfibrillar composites fabricated via multistage stretching extrusion. Fibers Polym. 2016, 17, 1916–1924. [Google Scholar] [CrossRef]
  16. Dong, J.H.; Qi, Y.H.; Sun, J.; Wei, L.Q.; Qin, S.H. In Situ fibrillation of poly(trimethylene terephthalate) in polyolefin elastomer through multistage stretching extrusion. J. Appl. Polym. Sci. 2016, 133, 43797. [Google Scholar] [CrossRef]
  17. Li, Z.-M.; Li, L.-B.; Shen, K.-Z.; Yang, M.-B.; Huang, R. In-Situ microfibrillar PET/iPP blend via slit die extrusion, hot stretching, and quenching: Influence of hot stretch ratio on morphology, crystallization, and crystal structure of iPP at a fixed PET concentration. J. Polym. Sci. Part B Polym. Phys. 2004, 42, 4095–4106. [Google Scholar] [CrossRef]
  18. Sun, J.; Luo, S.S.; Huang, A.R.; Shi, M.; Luo, H.; Wei, L.Q. Double yielding behavior of in situ microfibrillar polyolefin elasto-mer/poly(lactic acid) composites: Effect of microfibrillar morphology. Polym. Eng. Sci. 2020, 60, 1676–1685. [Google Scholar] [CrossRef]
  19. Shen, J.B.; Wang, M.; Li, J.; Guo, S.Y. In Situ fibrillation of polyamide 6 in isotactic polypropylene occurring in the laminat-ing-multiplying die. Polym. Adv. Technol. 2011, 22, 237–245. [Google Scholar] [CrossRef]
  20. Lin, B.; Sundararaj, U.; Mighri, F.; Huneault, M.A. Erosion and breakup of polymer drops under simple shear in high viscosity ratio systems. Polym. Eng. Sci. 2003, 43, 891–904. [Google Scholar] [CrossRef]
  21. Lin, B.; Mighri, F.; Huneault, A.M.A.; Sundararaj, U. Effect of Premade Compatibilizer and Reactive Polymers on Polystyrene Drop Deformation and Breakup in Simple Shear. Macromolecules 2005, 38, 5609–5616. [Google Scholar] [CrossRef]
  22. Zheng, Y.; Dong, R.; Shen, J.; Guo, S. Tunable Shape Memory Performances via Multilayer Assembly of Thermoplastic Polyurethane and Polycaprolactone. ACS Appl. Mater. Interfaces 2016, 8, 1371–1380. [Google Scholar] [CrossRef] [PubMed]
  23. Li, X.; Xin, C.; Huang, Y.; Kang, K.; He, Y. Effect of dispersed phase on the morphology of in situ microfibrils and the viscoelastic properties of its composite via direct extrusion. J. Appl. Polym. Sci. 2018, 135, 46286. [Google Scholar] [CrossRef]
  24. Crevecoeur, G.; Groeninckx, G. Fibril formation in in situ composites of a thermotropic liquid crystalline polymer in a thermoplastic matrix. J. Appl. Polym. Sci. 1993, 49, 839–849. [Google Scholar] [CrossRef]
  25. Yang, L.; Su, J.; Yang, Q.; Zhang, T.Y.; Zhao, Z.G.; Huang, Y.J.; Liao, X. Effective in situ polyamide 6 microfibrils in isotactic poly-propylene under microinjection molding: Significant improvement of mechanical performance. J. Mater. Sci. 2016, 51, 10386–10399. [Google Scholar] [CrossRef]
  26. Zhang, Y.; Park, S.-J. In Situ shear-induced mercapto group-activated graphite nanoplatelets for fabricating mechanically strong and thermally conductive elastomer composites for thermal management applications. Compos. Part A Appl. Sci. Manuf. 2018, 112, 40–48. [Google Scholar] [CrossRef]
  27. Migler, K.B. String Formation in Sheared Polymer Blends: Coalescence, Breakup, and Finite Size Effects. Phys. Rev. Lett. 2001, 86, 1023–1026. [Google Scholar] [CrossRef]
  28. Fakirov, S.; Bhattacharyya, D.; Lin, R.J.T.; Fuchs, C.; Friedrich, K. Contribution of Coalescence to Microfibril Formation in Polymer Blends during Cold Drawing. J. Macromol. Sci. Part B 2007, 46, 183–194. [Google Scholar] [CrossRef]
  29. Li, C.H.; Jing, T.; Wang, J.F.; Wu, H.; Guo, S.Y.; Zhang, X.; Li, J.; Shen, J.; Chen, R.; Xiong, Y. In Situ Formation of Microfibrillar Crystalline Superstructure: Achieving High-performance Polylactide. ACS Appl. Mater. Interfaces 2017, 9, 25818–25829. [Google Scholar] [CrossRef]
  30. Huang, Y.; He, Y.; Ding, W.; Yang, K.; Yu, D.; Xin, C. Improved viscoelastic, thermal, and mechanical properties of in situ microfibrillar polypropylene/polyamide 6,6 composites via direct extrusion using a triple-screw extruder. RSC Adv. 2017, 7, 5030–5038. [Google Scholar] [CrossRef] [Green Version]
  31. Cheng, L.H.; Wang, W.J.; Wang, J.W.; Cao, Y.X.; Li, G.X.; Shen, Y.L. Morphological structure and mechanical properties of in situ microfibrillar composites of modified PA66 with PP. J. Appl. Polym. Sci. 2013, 127, 4044–4051. [Google Scholar] [CrossRef]
  32. Yamaguchi, M.; Fukuda, K.; Yokohara, T.; Ali, M.A.B.M.; Nobukawa, S. Modification of rheological properties under elonga-tional flow by addition of polymeric fine fibers. Macromol. Mater. Eng. 2012, 297, 654–658. [Google Scholar] [CrossRef]
  33. Wu, D.F.; Zhang, Y.S.; Zhang, M.; Zhou, W.D. Phase behavior and its viscoelastic response of polylactide/poly(e-caprolactone) blend. Eur. Polym. J. 2008, 44, 2171–2183. [Google Scholar] [CrossRef]
  34. Lin, X.D.; Chen, W.L. Study of Poly(ethylene terephthalate)/Polypropylene Microfifibrillar Composites. I. Morphological Development in Melt Extrusion. Appl. Polym. Sci. 2003, 89, 1743. [Google Scholar] [CrossRef]
  35. Li, M.F.; Xiao, R.; Sun, G. Morphology development and size control of poly (trimethylene terephthalate) nanofibers prepared from poly(trimethylene terephthalate)/cellulose acetate butyrate in situ fibrillar composites. J. Mater. Sci. 2011, 46, 4524–4531. [Google Scholar] [CrossRef] [PubMed]
  36. Favis, B.; Chalifoux, J. Influence of composition on the morphology of polypropylene/polycarbonate blends. Polymer 1988, 29, 1761–1767. [Google Scholar] [CrossRef]
  37. Huang, W.-Y.; Shen, J.-W.; Chen, X.-M. Effect of composition on phase morphology and mechanical properties of PP/PA66 in situ composites via extrusion-drawing-injection method. J. Mater. Sci. 2003, 38, 541–547. [Google Scholar] [CrossRef]
  38. Jayanarayanan, K.; Jose, T.; Thomas, S.; Joseph, K. Effect of draw ratio on the microstructure, thermal, tensile and dynamic rheological properties of in situ microfibrillar composites. Eur. Polym. J. 2009, 45, 1738–1747. [Google Scholar] [CrossRef]
  39. Dong, J.; Huang, A.; Sun, J.; Wei, L.; Luo, S.; Qin, S. Effect of draw ratio on the morphologies and properties of in situ microfibrillar POE/PTT composites. Polym. Compos. 2018, 40, E629–E637. [Google Scholar] [CrossRef]
  40. Sun, J.; Huang, A.; Luo, S.; Shi, M.; Luo, H.; Sui, Y. Effect of stretching speed on morphologies and properties of in situ microfibrillar POE/PLA composites. J. Thermoplast. Compos. Mater. 2020, 35. [Google Scholar] [CrossRef]
  41. Xu, L.; Zhong, G.-J.; Ji, X.; Li, Z.-M. Crystallization behavior and morphology of one-step reaction compatibilized microfibrillar reinforced isotactic polypropylene/poly(ethylene terephthalate) (iPP/PET) blends. Chin. J. Polym. Sci. 2011, 29, 540–551. [Google Scholar] [CrossRef]
  42. Kuzmanović, M.; Delva, L.; Mi, D.; Martins, C.I.; Cardon, L.; Ragaert, K. Development of Crystalline Morphology and its rela-tionship with mechanical properties of PP/PET microfibrillar composites containing POE and POE-g-MA. Polymers 2018, 10, 291. [Google Scholar] [CrossRef] [PubMed]
  43. Friedrich, K.; Evstatiev, M.; Fakirov, S.; Evstatiev, O.; Ishii, M.; Harrass, M. Microfibrillar reinforced composites from PET/PP blends: Processing, morphology and mechanical properties. Compos. Sci. Technol. 2004, 65, 107–116. [Google Scholar] [CrossRef]
  44. Vahid, H.; Ali, M.Z.; Basil, D.F. Morphology development in poly (lactic acid)/polyamide11 biobased blends: Chain mobility and interfacial interactions. Polymer 2017, 120, 197–208. [Google Scholar]
  45. Li, W.J.; Schlarb, A.K.; Evstatiev, M. Effect of Viscosity Ratio on the Morphology of PET Microfifibrils in Uncompatibilized and Compatibilized Drawn PET/PP/TiO2 Blends. J. Polym. Sci. Part B Polym. Phys. 2009, 47, 555–562. [Google Scholar] [CrossRef]
  46. Favis, B.D. The effect of processing parameters on the morphology of an immiscible binary blend. J. Appl. Polym. Sci. 1990, 39, 285–300. [Google Scholar] [CrossRef]
  47. Utrack, L.A.; Shi, Z.H. Development of polymer blend morphology during compounding in a twin-screw extruder. Part I: Droplet dispersion and coalescence. Polym. Eng. Sci. 1992, 32, 1824–1833. [Google Scholar] [CrossRef]
  48. Yi, X.; Xu, L.; Wang, Y.; Zhong, G.J.; Ji, X.; Li, Z.M. Morphology and properties of isotactic polypropylene/poly(ethylene tereph-thalate) in situ microfifibrillar reinforced blends: Inflfluence of viscosity ratio. Eur. Polym. J. 2010, 46, 719. [Google Scholar] [CrossRef]
  49. Zhao, C.X.; Lun, H.M.; Alshrah, M.; Soltani, I.; Lee, P.C.; Park, C.B. Challenge in manufacturing nanofibril composites with low matrix viscosity: Effects of matrix viscosity and fibril content. Eur. Polym. J. 2019, 121, 109310. [Google Scholar] [CrossRef]
  50. Min, K.; White, J.L.; Fellers, J.F. Development of phase morphology in incompatible polymer blends during mixing and its variation in extrusion. Polym. Eng. Sci. 1984, 24, 1327–1336. [Google Scholar] [CrossRef]
  51. Zhu, X.L.; Wu, D.; Liu, C.L. Non-isothermal crystallization Kinetics of PA6/PPO blends. China Plast. 2012, 26, 29–34. [Google Scholar]
  52. Bai, H.; Huang, C.; Xiu, H.; Zhang, Q.; Fu, Q. Enhancing mechanical performance of polylactide by tailoring crystal morphology and lamellae orientation with the aid of nucleating agent. Polymer 2014, 55, 6924–6934. [Google Scholar] [CrossRef]
  53. Samir, M.A.S.A.; Alloin, F.; Sanchez, J.-Y.; Dufresne, A. Cellulose nanocrystals reinforced poly(oxyethylene). Polymer 2004, 45, 4149–4157. [Google Scholar] [CrossRef]
  54. Drieskens, M.; Peeters, R.; Mullens, J.; Franco, D.; Lemstra, P.J.; Hristova-Bogaerds, D.G. Structure versus properties relationship pf poly(lactic acid). I. Effect of crystallinity on barrier properties. J. Polym. Sci. Part B Polym. Phys. 2009, 47, 2247–2258. [Google Scholar] [CrossRef]
Polymers 14 04556 g001 550
Figure 1. Viscoelastic behavior of PA6 and PLA at 230 °C and viscosity ratio of PA6/PLA: (a) storage modulus (G′), (b) loss modulus (G″), (c) complex viscosity (η*), and (d) viscosity ratio of PA6/PLA.
Figure 1. Viscoelastic behavior of PA6 and PLA at 230 °C and viscosity ratio of PA6/PLA: (a) storage modulus (G′), (b) loss modulus (G″), (c) complex viscosity (η*), and (d) viscosity ratio of PA6/PLA.
Polymers 14 04556 g001
Polymers 14 04556 g002 550
Figure 2. (a–d) SEM images of in situ POE/(PLA/PA6) composites and (e,f) the PLA/PA6 microfibrils after etching the PLA, (i–l) Quantitative analyses of the PA6 phase after etching the PLA. (a,e,i) MFCs-0.5, (b,f,j) MFCs-2.2, (c,g,k) MFCs-5.3, (d,h,l) MFCs-14.2.
Figure 2. (a–d) SEM images of in situ POE/(PLA/PA6) composites and (e,f) the PLA/PA6 microfibrils after etching the PLA, (i–l) Quantitative analyses of the PA6 phase after etching the PLA. (a,e,i) MFCs-0.5, (b,f,j) MFCs-2.2, (c,g,k) MFCs-5.3, (d,h,l) MFCs-14.2.
Polymers 14 04556 g002
Polymers 14 04556 g003 550
Figure 3. Schematic diagram for the evolution of special-shaped microfibrils.
Figure 3. Schematic diagram for the evolution of special-shaped microfibrils.
Polymers 14 04556 g003
Polymers 14 04556 g004 550
Figure 4. Viscoelastic behavior of POE/(PA6/PLA) composites with different viscosity ratio of PA6 to PLA. (a) Storage Modulus(G′), (b) Loss Modulus(G″), (c) Complex Viscosity(η*).
Figure 4. Viscoelastic behavior of POE/(PA6/PLA) composites with different viscosity ratio of PA6 to PLA. (a) Storage Modulus(G′), (b) Loss Modulus(G″), (c) Complex Viscosity(η*).
Polymers 14 04556 g004
Polymers 14 04556 g005 550
Figure 5. (a–c) DSC heating curves and (d–f) DSC cooling curves of situ POE/(PA6/PLA) MFCs, (b,c) magnification of heating curves, (e,f) magnification of cooling curves.
Figure 5. (a–c) DSC heating curves and (d–f) DSC cooling curves of situ POE/(PA6/PLA) MFCs, (b,c) magnification of heating curves, (e,f) magnification of cooling curves.
Polymers 14 04556 g005
Polymers 14 04556 g006 550
Figure 6. Crystallization degree of PLA, PA6 and POE.
Figure 6. Crystallization degree of PLA, PA6 and POE.
Polymers 14 04556 g006
Polymers 14 04556 g007 550
Figure 7. Typical stress-strain curves and tensile properties of in situ POE/(PA6/PLA) composites along to extrusion direction. (a) Stress-strain curves, (b) Tensile properties.
Figure 7. Typical stress-strain curves and tensile properties of in situ POE/(PA6/PLA) composites along to extrusion direction. (a) Stress-strain curves, (b) Tensile properties.
Polymers 14 04556 g007
Polymers 14 04556 g008 550
Figure 8. Typical stress-strain curves and tensile properties of in situ POE/(PA6/PLA) composites perpendicular to extrusion direction. (a) Stress-strain, (b) Tensile properties.
Figure 8. Typical stress-strain curves and tensile properties of in situ POE/(PA6/PLA) composites perpendicular to extrusion direction. (a) Stress-strain, (b) Tensile properties.
Polymers 14 04556 g008
Table
Table 1. Physical parameters of POE and PLA.
Table 1. Physical parameters of POE and PLA.
SampleDensity (g/cm3)Melting Index (g/10 min)Tensile Strength at Break (MPa)Tensile Elongation at Break (%)
POE 82000.875.0 (190 °C)9.3>1000
PLA 4032D1.247.0 (210 °C) 536
Table
Table 2. Physical parameters of PA6.
Table 2. Physical parameters of PA6.
SamplePA6-2.0PA6-2.4PA6-2.8PA6-3.2
MaterialM2000M2400M2800M3400
Relative Viscosity2.072.462.813.28
Density (g/cm3)1.141.141.141.14
Melting Index (g/10 min)13734.615.26.5
Tensile Strength at Break (MPa)66616564
Tensile Elongation at Break (%)26393658
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Shi, M.; Wang, L.; Sun, J.; Yang, W.; Zhang, H. Morphology and Properties of Polyolefin Elastomer/Polyamide 6/Poly(lactic Acid) In Situ Special-Shaped Microfibrillar Composites: Influence of Viscosity Ratio. Polymers 2022, 14, 4556. https://doi.org/10.3390/polym14214556

AMA Style

Shi M, Wang L, Sun J, Yang W, Zhang H. Morphology and Properties of Polyolefin Elastomer/Polyamide 6/Poly(lactic Acid) In Situ Special-Shaped Microfibrillar Composites: Influence of Viscosity Ratio. Polymers. 2022; 14(21):4556. https://doi.org/10.3390/polym14214556

Chicago/Turabian Style

Shi, Min, Lijun Wang, Jing Sun, Wensheng Yang, and Hui Zhang. 2022. "Morphology and Properties of Polyolefin Elastomer/Polyamide 6/Poly(lactic Acid) In Situ Special-Shaped Microfibrillar Composites: Influence of Viscosity Ratio" Polymers 14, no. 21: 4556. https://doi.org/10.3390/polym14214556

APA Style

Shi, M., Wang, L., Sun, J., Yang, W., & Zhang, H. (2022). Morphology and Properties of Polyolefin Elastomer/Polyamide 6/Poly(lactic Acid) In Situ Special-Shaped Microfibrillar Composites: Influence of Viscosity Ratio. Polymers, 14(21), 4556. https://doi.org/10.3390/polym14214556

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop