Research

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20 pages, 5093 KiB

Open AccessArticle

Role of Plasticizers on PHB/bio-TPE Blends Compatibilized by Reactive Extrusion

by Kerly Samaniego, Armando Matos, Estefanía Sánchez-Safont, María V. Candal, Jose M. Lagaron, Luis Cabedo and Jose Gamez-Perez

Materials 2022, 15(3), 1226; https://doi.org/10.3390/ma15031226 - 07 Feb 2022

Cited by 7 | Viewed by 2848

Abstract

Poly(hydroxybutyrate) (PHB) is a biopolymer biologically synthesized by controlled bacterial fermentation from a wide variety of microorganisms. PHB is proposed as a potential green alternative to commonly used plastics in packaging, due to its biodegradability and biocompatibility. However, if PHB is to replace [...] Read more.

Poly(hydroxybutyrate) (PHB) is a biopolymer biologically synthesized by controlled bacterial fermentation from a wide variety of microorganisms. PHB is proposed as a potential green alternative to commonly used plastics in packaging, due to its biodegradability and biocompatibility. However, if PHB is to replace commodities, it has some limitations regarding its thermo-mechanical performance to overcome. Among them are its critically the low toughness values at room temperature and poor thermoforming ability. With the aim of overcoming these weaknesses, in this work, blends of PHB with the addition of a biodegradable thermoplastic elastomer (bio-TPE) were prepared and evaluated. Films of such compounds were made by cast extrusion. In order to enhance the compatibility of both polymers during the extrusion process, three different reactive agents (poly-hexametylene diisocianate, triglycidyl isocyanurate, and Joncryl^® ADR-4368) were assessed. The morphology and mechanical- and thermal properties of the films obtained were analyzed. In addition, the thermoforming ability of the produced films was evaluated. The results show that the plasticizers present in the bio-TPE interacted with the reactive agents, making them chemical competitors and altering the outcome of the blends. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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17 pages, 40226 KiB

Open AccessArticle

Effect of Printing Parameters on Mechanical Behaviour of PLA-Flax Printed Structures by Fused Deposition Modelling

by Yassine Elias Belarbi, Sofiane Guessasma, Sofiane Belhabib, Ferhat Benmahiddine and Ameur El Amine Hamami

Materials 2021, 14(19), 5883; https://doi.org/10.3390/ma14195883 - 08 Oct 2021

Cited by 15 | Viewed by 2101

Abstract

Few studies have reported the performance of Polylactic acid (PLA) flax feedstock composite for additive manufacturing. In this work, we report a set of experiments conducted by fused filament technology on PLA and PLA-flax with the aim of drawing a clear picture of [...] Read more.

Few studies have reported the performance of Polylactic acid (PLA) flax feedstock composite for additive manufacturing. In this work, we report a set of experiments conducted by fused filament technology on PLA and PLA-flax with the aim of drawing a clear picture of the potential of PLA-flax as a feedstock material. Nozzle and bed temperatures are both combined with the printing angle to investigate their influence on structural and mechanical properties. The study shows a low sensitivity of PLA-flax to process parameters compared to PLA. A varied balance between shearing and uniaxial deformation is found consistent with tensile results where filament crossing at −45/+45° provides the optimal load-bearing capabilities. However, Scanning Electron Microscopy (SEM) and high-speed camera recording shows a limiting reinforcing effect of flax fibre due to the presence of intra-filament porosity and a significant amount of fibre pull-out resulting from the tensile loading. These results suggest that the quality of the bond between PLA matrix and flax fibre, intra-filament porosity, and surface roughness should receive more attention as well as the need for more continuous fibre reinforcement in PLA filaments to optimise the performance of PLA-flax printed materials. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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25 pages, 10982 KiB

Open AccessEditor’s ChoiceArticle

Numerical and Experimental Results on Charpy Tests for Blends Polypropylene + Polyamide + Ethylene Propylene Diene Monomer (PP + PA + EPDM)

by Cătălin Pîrvu, Andreea Elena Musteată, George Ghiocel Ojoc and Lorena Deleanu

Materials 2020, 13(24), 5837; https://doi.org/10.3390/ma13245837 - 21 Dec 2020

Cited by 1 | Viewed by 2254

Abstract

This paper presents results from numerical and experimental investigation on Charpy tests in order to point out failure mechanisms and to evaluate new polymeric blends PP + PA6 + EPDM. Charpy tests were done for initial velocity of the impactor of 0.96 m/s [...] Read more.

This paper presents results from numerical and experimental investigation on Charpy tests in order to point out failure mechanisms and to evaluate new polymeric blends PP + PA6 + EPDM. Charpy tests were done for initial velocity of the impactor of 0.96 m/s and its mass of 3.219 kg and these data were also introduced in the finite element model. The proposed model takes into account the system of four balls, including support and the ring of fixing the three balls and it has a finer discretization of the impact area to highlight the mechanisms of failure and their development in time. The constitutive models for four materials (polypropylene with 1% Kritilen, two blends PP + PA6 + EPDM and a blend PA6 + EPDM) were derived from tensile tests. Running simulations for each constitutive model of material makes possible to differentiate the destruction mechanisms according to the material introduced in the simulation, including the initiation and the development of the crack(s), based on equivalent plastic strain at break (EPS) for each material. The validation of the model and the simulation results were done qualitatively, analyzing the shape of broken surfaces and comparing them to SEM images and quantitatively by comparing the impact duration, energy absorbed by the sample, the value of maximum force during impact. The duration of the destruction of the specimen is longer than the actual one, explainable by the fact that the material model does not take into account the influence of the material deformation speed in Charpy test, the model being designed with the help of tests done at 0.016 m/s (1000 mm/min) (maximum strain rate for the tensile tests). Experimental results are encouraging for recommending the blends 20% PP + 42% PA6 + 28% EPDM and 60% PA6 + 40% EPDM as materials for impact protection at low velocity (1 m/s). Simulation results are closer to the experimental ones for the more brittle tested materials (with less content of PA6 and EPDM) and more distanced for the more ductile materials (with higher content of PA6 and EPDM). Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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16 pages, 6289 KiB

Open AccessEditor’s ChoiceArticle

Photocurable Polymeric Blends for Surgical Application

by Teresa Cernadas, Marta Santos, Sónia P. Miguel, Ilídio J. Correia, Patrícia Alves and Paula Ferreira

Materials 2020, 13(24), 5681; https://doi.org/10.3390/ma13245681 - 12 Dec 2020

Cited by 2 | Viewed by 1734

Abstract

The preparation of photocrosslinkable bioadhesives synthesized from oligomers of lactic acid and polycaprolactone (PCL), both functionalized with 2-isocyanoethyl acrylate (AOI), were studied. The obtained modified macromers of LA-AOI (mLA) and PCL-AOI (mCL) were chemically characterized by ¹H NMR and used to formulate [...] Read more.

The preparation of photocrosslinkable bioadhesives synthesized from oligomers of lactic acid and polycaprolactone (PCL), both functionalized with 2-isocyanoethyl acrylate (AOI), were studied. The obtained modified macromers of LA-AOI (mLA) and PCL-AOI (mCL) were chemically characterized by ¹H NMR and used to formulate polymeric blends with different mass proportions, 1:1, 1:2 and 2:1, respectively. Subsequently, the produced blends were crosslinked, considering two UV irradiation times: 30 and 120 s. After their production, the thermal and mechanical properties of bioadhesives were assessed, where upon the rheology, gel content, hydrolytic degradation and dynamic contact angles were determined. Furthermore, the cytotoxic profile of bioadhesives was evaluated in contact with human dermal fibroblasts cells, whereas their antibacterial effect was studied monitoring Escherichia coli and S. aureus growth. Overall, flexible and resistant films were obtained, presenting promising features to be used as surgical bioadhesives. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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14 pages, 7275 KiB

Open AccessArticle

Modification of Surface Hydrophobicity of PLA/PE and ABS/PE Polymer Blends by ICP Etching and CF_x Coating

by Vedrana Lovinčić Milovanović, Cédric Guyon, Ivana Grčić, Michael Tatoulian and Domagoj Vrsaljko

Materials 2020, 13(23), 5578; https://doi.org/10.3390/ma13235578 - 07 Dec 2020

Cited by 5 | Viewed by 2602

Abstract

The flow regime inside the channel of 3D printed microreactors is defined by the surface properties of the channel walls. Polylactide (PLA) and acrylonitrile/butadiene/styrene (ABS) are two polymers that are the most common in additive manufacturing using fused filament fabrication, commonly known as [...] Read more.

The flow regime inside the channel of 3D printed microreactors is defined by the surface properties of the channel walls. Polylactide (PLA) and acrylonitrile/butadiene/styrene (ABS) are two polymers that are the most common in additive manufacturing using fused filament fabrication, commonly known as “3D printing”. With the aim of developing new materials for the 3D printing of microreactors whose channel surface hydrophobicity could be modified, PLA and ABS were blended with cheaper and widely used polymers-high-density polyethylene (PE-HD) and low-density polyethylene (PE-LD). Polymer blend surfaces were treated with inductively coupled plasma (ICP) and coated by fluorocarbon-based material (CF_x) plasma deposition treatment in order to modify surface hydrophobicity. It has been shown that the modification of surface morphology of PLA polymer blends can be achieved by ICP etching and CF_x coating, while this was not possible for ABS polymer blends under the conducted treatment conditions. The treated surface of PLA/PE-HD 90/10 showed a contact angle of 121.6° which is 36° higher than the contact angle measured on the untreated surface. Surfaces that have achieved contact angles higher than 120° have an “island like” surface morphology. Samples with higher “islands” showed higher contact angles, that confirmed that the hydrophobicity also depends on the height of the “islands”. Furthermore, it has been found that etching time significantly impacts the contact angle values and surface morphology of the PLA polymer blends, while the CF_x coating time does not have significant impact on the surface properties. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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17 pages, 5597 KiB

Open AccessArticle

Uncompatibilized PBAT/PLA Blends: Manufacturability, Miscibility and Properties

by Shen Su, Mona Duhme and Rodion Kopitzky

Materials 2020, 13(21), 4897; https://doi.org/10.3390/ma13214897 - 31 Oct 2020

Cited by 59 | Viewed by 7196

Abstract

Polymer blends of poly(butylene adipate-co-terephthalate) (PBAT) and polylactide (PLA) have been drawn attention due to the application potential as packaging or agricultural films. This study aims to determine the manufacturability, miscibility and mechanical properties of uncompatibilized PBAT/PLA blends prepared using different techniques. First, [...] Read more.

Polymer blends of poly(butylene adipate-co-terephthalate) (PBAT) and polylactide (PLA) have been drawn attention due to the application potential as packaging or agricultural films. This study aims to determine the manufacturability, miscibility and mechanical properties of uncompatibilized PBAT/PLA blends prepared using different techniques. First, PBAT and PLA are melt-blended in a wide range of ratios from 90/10 to 10/90. The compounds are then processed into pressed panels, flat films and blown films. Finally, the thermal, morphological, rheological and mechanical properties of these blends are investigated. PBAT/PLA blends have a small difference of solubility parameters, predicting theoretically good miscibility. However, they show two almost unchanged glass transition temperatures in the DSC, phase separation in SEM and two relaxation mechanisms in the Cole–Cole plot. The phase morphology varies depending on both the blend ratios and the preparation techniques. Tensile tests indicate that with increasing PLA content the elongation at break decreases. A good correlation between the elongation at break and the tear propagation resistance is found. Furthermore, the trouser tear method is proven to be more applicable to differentiate highly extensible blown films compared with the Elmendorf tear method. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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20 pages, 8733 KiB

Open AccessArticle

Properties of Styrene-Maleic Anhydride Copolymer Compatibilized Polyamide 66/Poly (Phenylene Ether) Blends: Effect of Blend Ratio and Compatibilizer Content

by Alper Aksit, Nico Geis, Merve Aksit and Volker Altstädt

Materials 2020, 13(15), 3400; https://doi.org/10.3390/ma13153400 - 31 Jul 2020

Cited by 2 | Viewed by 3462

Abstract

Two different blend ratios of polyamide 66 (PA66) and poly (2,6-dimethyl-1,4-phenylene ether) (PPE) (60/40 and 40/60 w/w) were produced via melt mixing. A styrene–maleic anhydride copolymer (SMA) was utilized at various contents from 2.5–15 wt% to compatibilize the immiscible blend [...] Read more.

Two different blend ratios of polyamide 66 (PA66) and poly (2,6-dimethyl-1,4-phenylene ether) (PPE) (60/40 and 40/60 w/w) were produced via melt mixing. A styrene–maleic anhydride copolymer (SMA) was utilized at various contents from 2.5–15 wt% to compatibilize the immiscible blend system. The influence of SMA content and blend ratio was investigated based on (thermo-) mechanical and morphological properties of the PA66/PPE blends. Correlations between the interaction of SMA with the blend partners were established. For 60/40 blends, a droplet-sea morphology was visualized by transmission electron microscopy, wherein no major changes were seen upon SMA addition. In the case of 40/60 blends, strong coalescence was found in the binary blend. Up to 5 wt% SMA, the coalescence was inhibited by the interfacial activity of SMA, whereas 10 wt% SMA initiated a disperse-to-co-continuous transition, which was completed at 15 wt% SMA. An enhancement of tensile properties was achieved for all blends possessing SMA, where the maximum concentration of 15 wt% resulted in the highest elongation at break and tensile strength values. The relative improvement of the tensile properties was higher with the PPE-rich blend (40/60) which was attributed to a partial emulsification of the PPE phases forming a bimodal PPE domain size distribution with nano-droplets in the range of 60–160 nm. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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15 pages, 5796 KiB

Open AccessArticle

Study on Preparation of Ultra-High-Molecular-Weight Polyethylene Pipe of Good Thermal-Mechanical Properties Modified with Organo-Montmorillonite by Screw Extrusion

by Zhouchao Guo, Rui Xu and Ping Xue

Materials 2020, 13(15), 3342; https://doi.org/10.3390/ma13153342 - 27 Jul 2020

Cited by 13 | Viewed by 2391

Abstract

The study of processing characteristic and property optimization of ultra-high-molecular-weight polyethylene (UHMWPE) pipe is increasingly performed, mainly focusing on difficulties in the melting process and poor thermal-mechanical properties after forming, which have limited the wider engineering application of UHMWPE pipe. In this study, [...] Read more.

The study of processing characteristic and property optimization of ultra-high-molecular-weight polyethylene (UHMWPE) pipe is increasingly performed, mainly focusing on difficulties in the melting process and poor thermal-mechanical properties after forming, which have limited the wider engineering application of UHMWPE pipe. In this study, organo-montmorillonite (OMMT)-modified UHMWPE pipe with good thermal-mechanical properties was prepared by screw extrusion molding. First, high-density polyethylene was subjected to fluidity modification so that the screw extrusion molding of UHMWPE pipe was feasible. Then, OMMT-modified UHMWPE pipes under different addition amounts of OMMT were innovatively prepared by extrusion. Furthermore, the effects of the addition amounts of the compatibilizer HDPE-g-MAH and the silane coupling agent γ-(2,3-epoxy propoxy) propyl trimethoxy silane (KH560) on the thermal properties of OMMT-modified UHMWPE pipe were investigated for the first time. Compared with those of pure UHMWPE pipe, the Vicat softening temperature (from 128 to 135.2 °C), thermal deformation temperature (from 84.4 to 133.1 °C), bending strength (from 27.3 to 39.8 MPa), and tensile strength (from 20.8 to 25.1 MPa) of OMMT-modified UHMWPE pipe were greatly increased. OMMT-modified UHMWPE pipe with good thermal-mechanical properties was able to be prepared by extrusion for the first time. The compatibilizer method of HDPE-g-MAH was slightly more effective than the coupling agent method of KH560. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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Review

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31 pages, 4139 KiB

Open AccessReview

The Effects of Copolymer Compatibilizers on the Phase Structure Evolution in Polymer Blends—A Review

by Ivan Fortelný and Josef Jůza

Materials 2021, 14(24), 7786; https://doi.org/10.3390/ma14247786 - 16 Dec 2021

Cited by 15 | Viewed by 2298

Abstract

This paper summarizes the results of studies describing the effect of block and graft copolymers on the phase structure formation and evolution in immiscible polymer blends. The main phenomenological rules for prediction of the copolymer compatibilization efficiency are briefly described and compared with [...] Read more.

This paper summarizes the results of studies describing the effect of block and graft copolymers on the phase structure formation and evolution in immiscible polymer blends. The main phenomenological rules for prediction of the copolymer compatibilization efficiency are briefly described and compared with selected experimental data. The results of the theories of equilibrium distribution of a copolymer between the blend interface and the bulk phases and its effect on the blend interfacial tension are summarized. The theories of the compatibilizer effect on the droplet breakup in flow are analyzed. The mechanisms of the copolymer effect on the coalescence of droplets in flow are compared and their effect on the droplet size is shown. The problems of reliable description of the effect of a copolymer on the coalescence in quiescent state are presented. Obstacles to derivation of a realistic theory of the copolymer effect on the competition between the droplet breakup and coalescence are discussed. Selected experimental data are compared with the theoretical results. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymer Blends)

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