Startseite Fracture behavior of highly toughened poly(lactic acid)/ethylene-co-vinyl acetate blends
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Fracture behavior of highly toughened poly(lactic acid)/ethylene-co-vinyl acetate blends

  • Qingtao Zeng , Yongqi Feng , Ruyin Wang und Piming Ma EMAIL logo
Veröffentlicht/Copyright: 5. September 2017
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Abstract

Poly(lactic acid) (PLA) is brittle which restricts the range of its applications. The toughness of PLA was effectively improved in this work by incorporation of rubber grade ethylene-co-vinyl acetate (EVM). For example, the elongation at break of PLA increased by about 50 times after the addition of the EVM (10–30 wt%), although the EVM was not miscible with the PLA matrix. Furthermore, the notched impact toughness of PLA/EVM blend (70/30 wt/wt) reached to 85 kJ/m2 even at a temperature as low as −10°C. The critical temperatures of brittle-to-ductile transition (BDT) for PLA/EVM blends are observed at −20~0°C depending on the composition, while no BTD transition appeared for neat PLA. The impact fracture surface morphology of PLA and PLA/EVM blends observed by SEM indicates that the toughening modification was achieved through obvious matrix yielding. Moreover, the toughening behavior of the PLA/EVM blends was also interpreted quantitatively by using a single-edge notched three-point bending model (SEN3PB). The SEN3PB experiments reveal that the fracture energy was consumed in an outer plastic zone away from the fracture surface rather than in the inner fracture process zone, which accounts for the high toughness of the PLA/EVM blends.

Keywords: fracture behavior; mechanism; poly(lactic acid); SEN3PB model; toughness

1 Introduction

In recent years, environmental pollution and ecological damage, caused by the non-biodegradable petroleum-based polymers such as polypropylene (PP), polyethylene (PE) and polystyrene (PS) have drawn more and more attention (1), (2). One of the effective methods to solve these issues is developing and using the biodegradable polymers, which are easy to degrade into innocuous substances like H2O and CO2 in natural ecosystem, to substitute for the non-biodegradable ones (3), (4).

Among the distinguished biodegradable polymers, poly(lactic acid) (PLA) is the one that has undergone the most extensive investigations. The good processability makes it possible for PLA to be manufactured into fibers, films, foams, and so on, by using the conventional processing techniques (5), which means that PLA has potential applications in various fields. However, the application range of PLA has been limited by some inherent defects, especially the brittleness, manifested by the low elongation at break and the low impact strength (6), (7). For example, the elongation at break and notched impact strength of PLA are around 6% and 13 J/m, which are <10% and 25% of that of poly(ethylene terephthalate) (PET), respectively (8). Therefore, toughening is required for the application of PLA.

Toughening strategies of PLA including chemical modification (i.e. copolymerization and transesterification) and physical blending (i.e. plasticization and polymer blending) have been explored (8), (9). Regardless of the lengthy reaction period and high cost, chemical modification is an effective way to improve the ductility of PLA. However, the changes (weakening in most instances) of the regularity of PLA chains usually cause serious loss in their crystallization capacity, and consequently reduce the thermostability (HDT) and mechanical strength of PLA (10), (11). Compared to chemical modification, physical blending is easier to do and more cost-effective, but the poor durability of the plasticized PLA products caused by the migration of micro-molecular plasticizers is always difficult to control (12), (13). In contrast, blending with other flexible or elastic polymers provides an alternative way to improve the toughness, and meanwhile has little influence on the mechanical strength of PLA (14), (15). Therefore, blending with other flexible polymers may be the optimal method to toughen PLA.

The flexible polymers used to toughen PLA can be divided into two categories. One is non-biodegradable polymers, like polyethylene (PE) (16), (17) and ethylene vinyl alcohol (EVOH) (18). The other is biodegradable polymers, such as poly(caprolactone) (PCL) (19), poly(butylene succinate) (PBS) (20), and poly(butylene adipate-co-terephthalate) (PBAT) (21), (22), (23). Regardless of the degradability, these flexible polymers are usually immiscible with the PLA matrix, leading to limited improvement on the toughness of PLA materials. Therefore compatibilization is essential to obtain suitable compatibility between the components, and consequently toughness of PLA blends. Compatibilization can be realized by incorporating pre-made copolymers or through in-situ reaction between the components during blending. Hillmyer et al. (16), (17) prepared a series of PE-PLA block copolymers (PE-b-PLA), and found that the incorporation of PE-b-PLA significantly improved the compatibility of the PLA/PE blends, and this enhancement of PE-b-PLA was largely determined by the molecular weight ratio of the two segments. Dicumyl peroxide (DCP) was widely used as a free radical initiator to initiate grafting between different polymers (24). In-situ compatibilization of PLA/PCL (19) and PLA/PBS (20) blends was achieved by adding DCP, which significantly reduced the particle size of the dispersed PCL and PBS, and increased the interfacial adhesion with the PLA matrix. Consequently the toughness of the PLA/PCL and PLA/PBS blends was improved. Zhang et al. (21) compounded PLA and PBAT with T-GMA, a random copolymer of ethylene, acrylic ester and glycidyl methacrylate (1–10 wt%). The epoxy groups of T-GMA reacted with the terminal carboxyl groups of PLA and PBAT during melt blending, imparting the compatibility to the PLA/PBAT blends, and therefore enhanced the impact strength and elongation at break of the blends, without much of a decrease in the mechanical strength. A series of epoxide-type chain extenders such as Joncryl® (22), (23), with a similar structure to T-GMA, are also able to toughen the blends of PLA and flexible polyester through reactive compatibilization.

Ethylene-co-vinyl acetate copolymer (EVM) is another elastic polymer that is commonly used to toughen PLA. Good compatibility between PLA and EVM was achieved without additional compatibilization (25), (26). Although a lot work has been done on toughening modification of PLA (27), (28), (29), (30), the low-temperature impact behavior was seldom reported, and the quantitative analysis of energy dissipation under fracture has also not been well understood yet.

Therefore, the prime objectives of this work are to achieve low-temperature toughness of PLA by incorporation of a rubber grade of ethylene-vinyl acetate copolymer (EVM) and to quantitatively reveal the energy dissipation of the PLA/EVM blends during fracture. For this purpose, a so-called single-edge notched three-point bending (SEN3PB) experiment was carried out on the PLA/EVM blends, and the miscibility, the mechanical properties, the temperature dependence of notched impact toughness and the fracture surface morphology for the PLA/EVM blends were investigated.

2 Experimental

2.1 Materials

PLA-2002D was purchased from Nature Works LLC (Blair, Nebraska, USA). The Mw and Mw/Mn are 180 KDa and 1.7, respectively, and the content of d-lactide is approximately 4%. EVM (Levapren®) with VA content ~50 wt% was kindly supplied by Lanxess Chemical Co., Ltd. (Köln, Germany). The Tg is about −29°C measured by DSC at a heating rate of 10°C/min, and the density is ~1000 kg/m3. The structures of PLA and EVM are shown in Figure 1.

Figure 1: The structures of (A) PLA and (B) EVM.
Figure 1:

The structures of (A) PLA and (B) EVM.

2.2 Blend preparation

Prior to blending, both PLA resin and EVM rubber were dried at 50°C in vacuum for 12 h. Binary blends of PLA and EVM with designed compositions (i.e. 100/0, 90/10, 85/15, 80/20 and 70/30, mass ratio) were melt-blended in a mixing chamber of a HAAKE rheometer (Rheocord 90, Mess-Technic GmbH, Germany) at 170°C for 4 min, with a rotating speed of 40 rpm. The melt-blended samples were dehumidified and then compression molded at 170°C for 3 min. The compression-molded samples were used for further testing and characterizations.

2.3 Characterizations

2.3.1 Tensile properties

Tensile properties of the PLA and PLA/EVM blends were measured by using a Zwick Z100 tensile tester (Zwick Z100, Ulm, Germany) at a crosshead speed of 10 mm/min. The dimensions of the dumbbell-shaped tensile bars were 12 mm in length of narrow parallel-sided portion, 0.8 mm in thickness and 2 mm in width. All the tensile tests were performed at ambient temperature.

2.3.2 Notched Izod impact test

The impact toughness for the PLA and PLA/EVM blends were determined by the notched Izod impact test using an impact analyzer (Zwick 5102, Ulm, Germany) and the analysis was performed according to ASTM D-256. Dimensions of the specimen for the notched Izod impact test were 63.5×12.7×3.6 mm3.

2.3.3 Scanning electron microscopy (SEM)

The morphological characterization of the cryogenically fractured surfaces and the impact fracture surfaces of the PLA/EVM blends was performed by using SEM (Quanta 3D, FEI, Eindhoven, The Netherlands). The samples were sputter-coated with a thin gold layer before SEM measurements. To visualize the phase morphology better, the cryogenically fractured surfaces were etched with a xylene/methyl ethyl ketone (60/40) mixture for 2 h to remove the EVM phase before observation.

2.3.4 Single-edge notched three-point bending (SEN3PB) experiments

The same specimen as for notched Izod impact test was also used for SEN3PB measurement. Sharp notches with different depths were made with a fresh razor blade. Then, three-point bending experiments were performed on these “single-edge notched” samples. The geometry of the specimen will be discussed. The ligament length (l) was measured from the initial crack tip to the beginning of the hinge and the total fracture energy was calculated from the area under load – displacement curves.

3 Results and discussion

3.1 Miscibility of the PLA/EVM blends

The toughening effect of rubber on plastic depends largely on their miscibility and phase morphology, therefore, the morphology of cryogenically fractured surfaces of the PLA/EVM blends was observed using SEM. The EVM phase was etched before any observation, so that the holes left in the PLA matrix could reflect its dispersion.

As shown in Figure 2, notable sea-island phase morphology is observed for all the PLA/EVM blends, which indicates that EVM is not miscible with the PLA matrix under the studied dosages. This conclusion is further supported by the DMA and DSC characterizations on the PLA and PLA/EVM blend, showing two separated Tg of the PLA/EVM blend, as shown in Figures S1 and S2 of the supporting information. There is no big difference on phase morphology among the PLA/EVM blends, except that the size of EVM domains (the dark holes) increases with increasing the EVM content. It has to be remarked that EVM is still the dispersed phase with a diameter of around 3 μm when its content is as high as 30 wt% (Figure 2D).

Figure 2: SEM images of cryogenically fractured surfaces of the PLA/EVM (wt/wt) blends.(A) 90/10, (B) 85/15, (C) 80/20 and (D) 70/30. The fracture surfaces were etched with a xylene/methyl ethyl ketone (60/40) mixture for 2 h to remove the EVM phase before observation.
Figure 2:

SEM images of cryogenically fractured surfaces of the PLA/EVM (wt/wt) blends.

(A) 90/10, (B) 85/15, (C) 80/20 and (D) 70/30. The fracture surfaces were etched with a xylene/methyl ethyl ketone (60/40) mixture for 2 h to remove the EVM phase before observation.

3.2 Mechanical properties of the PLA/EVM blends

The tensile strength and the elongation at break of the PLA/EVM blends are presented in Figure 3. Neat PLA has a strength of about 72 MPa with a low elongation at break of 7%, which bear out the inherent brittleness of PLA. Owing to the elastomeric nature of the EVM, the tensile strength of the PLA/EVM blends decrease gradually with increasing the EVM content, whereas, it is still above 35 MPa at 30 wt% of the EVM. In contrast, the elongation at break increases steeply after the addition of 10 wt% of the EVM. Compared to the neat PLA, the elongation at break of PLA/EVM (90/10) increases to around 380%, increases by more than 50 times. However, the elongation at break leveled off at higher EVM content.

Figure 3: Tensile strength and elongation at break as a function of the EVM content of the PLA/EVM blends.
Figure 3:

Tensile strength and elongation at break as a function of the EVM content of the PLA/EVM blends.

3.3 Temperature dependence of toughness for the PLA/EVM blends

3.3.1 Notched impact toughness

Rubber-toughened plastics can be very brittle at low temperatures, because the shear modulus of the rubber phase dramatically increases when the temperature approaches Tg of the rubber phase which promotes the resistance of rubber cavitation or deformation (31). In order to discuss the temperature dependence of toughness for the PLA/EVM blends, notched Izod impact tests were performed at different temperatures (i.e. −60, −35, −25, −17.5, −10, 0, 10 and 23°C, respectively).

Figure 4 plots the notched impact toughness as a function of temperature and composition. No brittle-to-ductile transition (BDT) for the neat PLA is observed as a function of temperature, because PLA is brittle at all the examined temperatures (<Tg of PLA). The BDT temperature for an amorphous polymer is assumed to be situated near its Tg. Above Tg amorphous polymers are flexible; while below Tg the applied strain cannot be effectively delocalized showing brittle behavior during deformation (32).

Figure 4: Notched impact toughness of the PLA and PLA/EVM blends as a function of temperature.
Figure 4:

Notched impact toughness of the PLA and PLA/EVM blends as a function of temperature.

The BDT represents a transition in major deformation mechanisms from shear yielding to crazing, or vice versa, accompanied by a sudden change in crack resistance (32), (33). For rubber-toughened plastics, there is a critical temperature at which BDT occurs. As shown in Figure 4, the critical temperatures of BDT for the PLA/EVM blends are below zero and shift to lower values when the rubber content increases. For example, the BDT temperatures for PLA/EVM (80/20) and PLA/EVM (70/30) are approximately −10°C and −25°C, respectively. What is surprising is that an impact toughness of 85 kJ/m2 can be obtained for the highly toughened PLA/EVM blends even at a temperature low as −10°C. These results demonstrate that EVM can significantly enhance the toughness of PLA also at low temperatures.

3.3.2 Impact fracture surface morphology

For a better understanding of the fracture behavior of the EVM toughened PLA, the morphology of impact fracture surfaces (23°C) of the PLA and PLA/EVM blends were observed by using SEM, as shown in Figure 5.

Figure 5: SEM images of impact fracture surfaces.(A) PLA, (B) PLA/EVM (90/10), (C) PLA/EVM (85/15) and (D) PLA/EVM (80/20).
Figure 5:

SEM images of impact fracture surfaces.

(A) PLA, (B) PLA/EVM (90/10), (C) PLA/EVM (85/15) and (D) PLA/EVM (80/20).

In a typical rubber toughened plastic system, the domains of rubber/elastomer usually act as stress concentrators under stress like the impact testing. These domains generate interfacial debonding from the plastic matrix under a triaxial stress, resulting in the formation of voids (i.e. cavitations) and triggering the deformation/yielding of surrounding plastic matrix (i.e. crazing). And the fibrils formed along with interfacial debonding will absorb energy until their rupture. Hence, the impact energy is dissipated by cavitations, fibrillation and crazing, resulting in the improvement of toughness (34), (35). Regarding the PLA/EVM blends, the flexible EVM domains acted as stress concentrators during the impact testing, and the PLA matrix between EVM domains deformed more easily to achieve yielding. As shown in Figure 5, a brittle to ductile transition under impact testing at room temperature can be observed after the addition of EVM. The fracture surface of PLA is very smooth (Figure 5A), which identifies with the typical fracture surface for a brittle plastic. In contrast, the fracture surface of PLA/EVM (90/10) becomes relatively rough, with a small quantity of elongated fibrils and big cracks appeared (Figure 5B), which is in accordance with the improved the toughing effect caused by 10% EVM (see Figure 4). With increasing the EVM content, the elongated fibrils become thicker, making the fracture surface of PLA/EVM (85/15) much rougher, and some tiny deformations of PLA matrix can be observed (Figure 5C). The deformation of PLA matrix becomes more obvious for PLA/EVM (80/20) (Figure 5D). These results demonstrate that the interfacial adhesion between the PLA matrix and EVM domains is strong, and the shear yielding of PLA matrix occurred during the impact testing when the content of EVM reaches 20 wt%. Therefore, the high impact toughness of the PLA/EVM blends is mainly ascribed to the rubber initiated matrix yielding. It has to be remarked that the PLA used in this work possesses low optical purity, consequently, no crystallization of PLA or PLA/EVM was observed after processing, as confirmed by the XRD patterns (Figure S3). Thus, the effect of crystallinity on the toughness of the PLA/EVM blends is eliminated.

3.4 Single-edge notched three-point bending experiments

Standard Izod and Charpy impact testing are commonly used to characterize the toughness of plastics due to the convenience of these two methods. However, these two methods are limited to provide sufficient information regarding the fracture mechanism, e.g. fail to quantitatively reveal the way of energy dissipation during the impact testing. In order to quantitatively reveal the toughening mechanism of PLA/EVM blends, a so-called SEN3PB experiment was used for these samples.

Data from these tests were analyzed by a modified essential work of fracture (EWF) model based on Mai and his coworkers’ study (36), (37), which originated from Broberg’s unified fracture theory (38), (39). In this model (40), (41), the total fracture energy, U, per unit fracture surface area, A, is given by equation 1,

[1]UA=uo+udℓ

where uo is the limiting specific fracture energy corresponding to the energy assuming in the inner fracture process zone (near or at the fracture surface). ud is the dissipative energy density associating with energy absorbing process, e.g. cavitation and matrix yielding, in an outer plastic zone away from the fracture surface. ℓ is the ligament length (as shown in Figure 6). In this equation, uo and ud are considered as phenomenological parameters, not material parameters.

Figure 6: Schematic geometry of a single-edge notched three-point bending (SEN3PB) specimen, showing the ligament length (ℓ), width (W), thickness (t), inner process zone (uo), and outer plastic zone (ud).
Figure 6:

Schematic geometry of a single-edge notched three-point bending (SEN3PB) specimen, showing the ligament length (ℓ), width (W), thickness (t), inner process zone (uo), and outer plastic zone (ud).

Figure 7 shows the load versus displacement diagrams for the PLA and PLA/EVM blends. For each PLA specimen under the stress conditions imposed here, the load reaches a maximum value immediately before sharply dropping off in the manner of a brittle fracture, as shown in Figure 7A. After specimen yielding, the load trails off slowly rather than dropping sharply for PLA/EVM (90/10) and PLA/EVM (80/20), as shown in Figure 7B, C. This extended tail after the specimen’s yielding is typical of ductile materials. In the case of similar ligament lengths, the higher EVM content, the more total fracture energy can be gained. The toughening effect of EVM content observed in SEN3PB experiments is very consistent with the results of notched Izod impact testing.

Figure 7: Load versus displacement diagrams for SEN3PB specimens of the PLA and PLA/EVM blends as a function of ligament lengths (ℓ) and EVM loadings.(A) PLA, (B) PLA/EVM (90/10) and (C) PLA/EVM (80/20).
Figure 7:

Load versus displacement diagrams for SEN3PB specimens of the PLA and PLA/EVM blends as a function of ligament lengths (ℓ) and EVM loadings.

(A) PLA, (B) PLA/EVM (90/10) and (C) PLA/EVM (80/20).

The total fracture energy per unit fracture area (U/A) of each specimen is plotted versus the corresponding ligament lengths (ℓ), as shown in Figure 8. For the samples examined here, a good linearity of these plots is achieved. The uo and ud values for each sample, as suggested above, are obtained from the slopes and intercepts of these lines, respectively, and are shown in Figure 9.

Figure 8: U/A values for PLA and PLA/EVM blends as a function of ligament lengths (ℓ).
Figure 8:

U/A values for PLA and PLA/EVM blends as a function of ligament lengths (ℓ).

Figure 9: The results show that the fracture energy assuming on the outer plastic zone (ud) is increasing with the EVM content while energy assuming at the fracture surface is decreasing.(A) uo and (B) ud for PLA and PLA/EVM blends as a function of EVM content.
Figure 9:

The results show that the fracture energy assuming on the outer plastic zone (ud) is increasing with the EVM content while energy assuming at the fracture surface is decreasing.

(A) uo and (B) ud for PLA and PLA/EVM blends as a function of EVM content.

The slope of the line (ud) corresponding to neat PLA is approximately 0 indicating that almost all the fracture work is done in the region near the fracture surface and very little energy is dissipated in the outer plastic zone. The uo of the samples increased with EVM content up to 10 wt% and then reduced gradually. On the other hand, the ud values monotonically increased with increasing EVM content, which is consistent with the varying trend of notched izod impact toughness. These results indicate that a small amount of EVM (<10 wt%) can contribute to a certain extent to the fracture energy at the fracture surface as well as in the outer plastic zone. However, it is the ud (energy absorbing in an outer plastic zone away from the fracture surface) rather than uo that mainly accounts for the high toughness of PLA/EVM blends. This statement is confirmed by a large volume of stress whitening that extends below the fracture surfaces for EVM toughened PLA materials, while there is no such evidence at all for neat PLA.

3.5 Comparsion of the toughening efficiency of the PLA/EVM blends with other PLA-based composites

For a better understanding of the remarkable toughening effect of EVM, a comparison of the notched impact toughness between these PLA/EVM blends and other reported PLA-based materials was investigated and the literature survey is shown in Figure 10. PLA usually shows low impact toughness (~2 kJ/m2) with low elongation at break (~6%) owing to its inherent brittleness, while toughening agents can improve the impact toughness and/or elongation at break of PLA in varying degrees, as shown in Figure 10. However, a compatibilizer is usually essential to accomplish the toughening, and the balance between impact toughness and elongation was sometimes achieved, e.g. the PLA/LLDPE/PLLA-b-PE and PLA/PBAT/T-GMA blends. It is interesting that high impact toughness together with a high elongation at break of PLA were realized simultaneously by incorporation of 30 wt% EVM. The toughness of this blend is even higher than that of the NatureWorks product, i.e. PLA/TPU (70/30 wt/wt). Considering that there is no need of an extra compatibilizer for the PLA/EVM system, it may provide a simple method to the production of highly toughened PLA-based materials.

Figure 10: A comparison of the toughening effects on PLA between EVM and other reported toughening modifiers (6), (8), (17), (20), (21), (27), (28), (42), (43), (44), (45), (46).PLLA-b-PE, a PLLA-PE block copolymers; TKGM, thermoplastic konjac glucomannan; MGST, MA-grafted starch; SEBS, hydrogenated styrene-butadiene-styrene block copolymer; EGMA, poly(ethylene-co-glycidyl methacrylate); GMA-g-POE, glycidyl methacrylate grafted poly(ethylene octane); T-GMA, a random copolymer of ethylene, acrylic ester and GMA.
Figure 10:

A comparison of the toughening effects on PLA between EVM and other reported toughening modifiers (6), (8), (17), (20), (21), (27), (28), (42), (43), (44), (45), (46).

PLLA-b-PE, a PLLA-PE block copolymers; TKGM, thermoplastic konjac glucomannan; MGST, MA-grafted starch; SEBS, hydrogenated styrene-butadiene-styrene block copolymer; EGMA, poly(ethylene-co-glycidyl methacrylate); GMA-g-POE, glycidyl methacrylate grafted poly(ethylene octane); T-GMA, a random copolymer of ethylene, acrylic ester and GMA.

4 Conclusions

A commercial ethylene-co-vinyl acetate copolymer, EVM, was used to toughen PLA in this work. Although the EVM is not miscible with the PLA matrix, it can increase the elongation at break of PLA by around 50 times. And the EVM can significantly improve the impact toughness of PLA even at varied temperatures. No brittle-to-ductile transition (BDT) for PLA appears at temperatures below 23°C (<Tg of PLA), in contrast, the critical temperatures of BTD for PLA/EVM blends are observed in the range of −20~0°C, which shifts to lower values with the increase of EVM content. The relatively smooth impact fracture surface for PLA become extremely rough after adding EVM, with some voids and different degrees of fibrillation, indicating that the high toughness of PLA/EVM blends is achieved by matrix yielding.

SEN3PB experiments were performed to quantitatively reveal the toughening mechanism of EVM. For PLA, the load reaches a maximum value immediately and then sharply dropping off in the manner of brittle fracture, on the contrary, the load trails off slowly after specimen yielding for PLA/EVM blends, which is typical of ductile materials. The essential work of fracture (EWF) model analysis showed that almost all the fracture work is done in the region near the fracture surface and very little energy is dissipated in the outer plastic zone for PLA. On the contrary, the energy absorbing that dominantly occurred in an outer plastic zone away from the fracture surface mainly accounts for the high toughness of PLA/EVM blends. This work may provide a simple but efficient method to produce highly toughened PLA-based materials.

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Supplemental Material:

The online version of this article offers supplementary material (https://doi.org/10.1515/epoly-2017-0114).

Received: 2017-6-10
Accepted: 2017-7-31
Published Online: 2017-9-5
Published in Print: 2018-2-23

©2018 Walter de Gruyter GmbH, Berlin/Boston

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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  1. Frontmatter
  2. In this Issue
  3. Full length articles
  4. Poly(imide-siloxane)s based on hyperbranched polyimides
  5. Electrochemical, optical and morphological properties of poly (N-vinylcarbazole/TiO2) and (N-vinylcarbazole/aniline)/TiO2 copolymer prepared by electrochemical polymerization
  6. Synthesis and application of a novel core-shell-shell magnetic ion imprinted polymer as a selective adsorbent of trace amounts of silver ions
  7. New insights on solvent implications in flow behavior and interfacial interactions of hydroxypropylmethyl cellulose with cells/bacteria
  8. Electrochemical behavior, characterization and corrosion protection properties of poly(bithiophene+2-methylfuran) copolymer coatings on A304 stainless steel
  9. Fracture behavior of highly toughened poly(lactic acid)/ethylene-co-vinyl acetate blends
  10. Poly(N-isopropylacrylamide)-coated gold nanorods mediated by thiolated chitosan layer: thermo-pH responsiveness and optical properties
  11. Cryostructuring of polymer systems. 47. Preparation of wide porous gelatin-based cryostructurates in sterilizing organic media and assessment of the suitability of thus formed matrices as spongy scaffolds for 3D cell culturing
  12. Controlled drug delivery of ciprofloxacin from ultrasonic hydrogel
  13. Communication
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https://doi.org/10.1515/epoly-2017-0114
Schlagwörter für diesen Artikel
fracture behavior; mechanism; poly(lactic acid); SEN3PB model; toughness
Creative Commons
BY-NC-ND 3.0

Artikel in diesem Heft

  1. Frontmatter
  2. In this Issue
  3. Full length articles
  4. Poly(imide-siloxane)s based on hyperbranched polyimides
  5. Electrochemical, optical and morphological properties of poly (N-vinylcarbazole/TiO2) and (N-vinylcarbazole/aniline)/TiO2 copolymer prepared by electrochemical polymerization
  6. Synthesis and application of a novel core-shell-shell magnetic ion imprinted polymer as a selective adsorbent of trace amounts of silver ions
  7. New insights on solvent implications in flow behavior and interfacial interactions of hydroxypropylmethyl cellulose with cells/bacteria
  8. Electrochemical behavior, characterization and corrosion protection properties of poly(bithiophene+2-methylfuran) copolymer coatings on A304 stainless steel
  9. Fracture behavior of highly toughened poly(lactic acid)/ethylene-co-vinyl acetate blends
  10. Poly(N-isopropylacrylamide)-coated gold nanorods mediated by thiolated chitosan layer: thermo-pH responsiveness and optical properties
  11. Cryostructuring of polymer systems. 47. Preparation of wide porous gelatin-based cryostructurates in sterilizing organic media and assessment of the suitability of thus formed matrices as spongy scaffolds for 3D cell culturing
  12. Controlled drug delivery of ciprofloxacin from ultrasonic hydrogel
  13. Communication
  14. Synthesis and thermal properties of poly(vinylcyclohexane)-b-poly(4-vinylpyridine) diblock copolymers prepared via RAFT polymerization
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