Functionalization, compatibilization and properties of polyolefin composites with natural fibers

The article is focused on analyzing the effect of functionalization and reactive processing on the morphological, thermal, rheological and mechanical properties of composites of isotactic polypropylene (PP), polystyrene (PS), poly(ethylene-vinyl acetate) (EVA), with cellulose fibers, hemp or oat as natural fillers. Both polymers and fibers were modified with bi-functional monomers (glycidyl methacrylate, GMA; maleic anhydride, MA) capable of facilitating chemical reactions between the components during melt mixing. Polyolefin copolymers containing reactive groups (PP-g-GMA, SEBS-g-MA, PS-co-MA, etc.) were used as compatibilizers. Optical and SEM microscopy, FTIR, RX, DSC, TGA, DMTA, rheological and mechanical tests were employed for the composites characterization. The properties of binary and ternary systems have been analyzed as a function of both fiber and compatibilizer content. All compatibilized systems showed enhanced fiber dispersion and interfacial adhesion. The phase behavior and the thermal stability of the composites were affected by the chemical modification of the fibers. Marked changes in the overall crystallization processes and crystal morphology of PP composites were observed owing to the nucleating effect of the fibers. The tensile mechanical behavior of the compatibilized composites generally resulted in a higher stiffness, depending on the fiber amount and the structure and concentration of compatibilizer.Fil: Pracella, Mariano. Institute of Composite and Biomedical Materials; ItaliaFil: Minhaz-Ul Haque, M.. Universita Degli Studi Di Pisa; ItaliaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentin

A comparative study on the effect of different reactive compatibilizers on injection-molded pieces of bio-based high-density polyethylene/polylactide blends

This is the peer reviewed version of the following article: Quiles-Carrillo, L., Montanes, N., Jorda-Vilaplana, A., Balart, R. and Torres-Giner, S. (2019), A comparative study on the effect of different reactive compatibilizers on injection-molded pieces of bio-based high-density polyethylene/polylactide blends. J. Appl. Polym. Sci., 136, 47396, which has been published in final form at https://doi.org/10.1002/APP.47396. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] The present study reports on the development of binary blends consisting of bio-based high-density polyethylene (bio-HDPE) with polylactide (PLA), in the 5¿20 wt % range, prepared by melt compounding and then shaped into pieces by injection molding. In order to enhance the miscibility between the green polyolefin and the biopolyester, different reactive compatibilizers were added during the melt-blending process, namely polyethylene grafted maleic anhydride (PE-g-MA), poly(ethylene-co-glycidyl methacrylate) (PE-co-GMA), maleinized linseed oil (MLO), and a combination of MLO with dicumyl peroxide (DCP). Among the tested compatibilizers, the dual addition of MLO and DCP provided the binary blend pieces with the most balanced mechanical performance in terms of rigidity and impact strength as well as the highest thermal stability. The fracture surface of the binary blend piece processed with MLO and DCP revealed the formation of a continuous structure in which the dispersed PLA phase was nearly no discerned in the bio-HDPE matrix. The resultant miscibility improvement was ascribed to both the high solubility and plasticizing effect of MLO on the PLA phase as well as the crosslinking effect of DCP on both biopolymers. The latter effect was particularly related to the formation of macroradicals of each biopolymer that, thereafter, led to the in situ formation of bio HDPE-co-PLA copolymers and also to the development of a partially crosslinked network in the binary blend. As a result, cost-effective and fully bio-based polymer pieces with improved mechanical strength, high toughness, and enhanced thermal resistance were obtained.This research was funded by the EU H2020 project YPACK (reference number 773872) and by the Ministry of Science, Innovation, and Universities (MICIU, project numbers MAT2017-84909-C2-2-R and AGL2015-63855-C2-1-R). Quiles-Carrillo and Torres-Giner are recipients of a FPU grant (FPU15/03812) from the Spanish Ministry of Education, Culture, and Sports (MECD) and a Juan de la Cierva contract (IJCI-2016-29675) from the MICIU, respectively.Quiles-Carrillo, L.; Montanes, N.; Jorda-Vilaplana, A.; Balart, R.; Torres-Giner, S. (2019). 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Functionalization, Compatibilization and Properties of Polyolefin Composites with Natural Fibers

The article is focused on analyzing the effect of functionalization and reactive processing on the morphological, thermal, rheological and mechanical properties of composites of isotactic polypropylene (PP), polystyrene (PS), poly(ethylene-vinyl acetate) (EVA), with cellulose fibers, hemp or oat as natural fillers. Both polymers and fibers were modified with bi-functional monomers (glycidyl methacrylate, GMA; maleic anhydride, MA) capable of facilitating chemical reactions between the components during melt mixing. Polyolefin copolymers containing reactive groups (PP-g-GMA, SEBS-g-MA, PS-co-MA, etc.) were used as compatibilizers. Optical and SEM microscopy, FTIR, RX, DSC, TGA, DMTA, rheological and mechanical tests were employed for the composites characterization. The properties of binary and ternary systems have been analyzed as a function of both fiber and compatibilizer content. All compatibilized systems showed enhanced fiber dispersion and interfacial adhesion. The phase behavior and the thermal stability of the composites were affected by the chemical modification of the fibers. Marked changes in the overall crystallization processes and crystal morphology of PP composites were observed owing to the nucleating effect of the fibers. The tensile mechanical behavior of the compatibilized composites generally resulted in a higher stiffness, depending on the fiber amount and the structure and concentration of compatibilizer

Crosslinked polyvinyl acetate reinforced with cellulose nanocrystals – : Characterization of structure and mechanical properties

The structure of cellulose based nanocomposites influences their final mechanical properties significantly. Obtaining good dispersion of hydrophilic nanocellulose materials in hydrophobic polymer matrix is challenging. Here two unique methods were developed to improve the dispersion of cellulose nanocrystals (CNC) in polyvinyl acetate (PVAc) matrix. One is in-situ polymerization of vinyl acetate in the presence of CNCs, and the other one is crosslinking of PVAc by sodium tetraborate (Borax), which restricts the movement of CNCs during the drying process. The results from atomic force microscopy (AFM) show that the in-situ CNC/PVAc emulsion has much better dispersion than the one produced by stirring. Moreover, the mechanical characterization indicates that the in-situ composite with 10 wt% CNC has higher strength compared to the stirred composite with the same CNC concentration. The mechanical properties of crosslinked PVAc materials can be varied by changing the pH and may be attributed to differences of the crosslinking degree. Further investigations of the restriction effect caused by borax are needed.Godkänd; 2015; 20160331 (shigen

Compatibilization and properties of EVA copolymers containing surface-functionalized cellulose microfibers

Cellulose microfibers were modified with two different bi-functional monomers. Composites of EVA copolymer with modified and unmodified cellulose were prepared by melt mixing. The samples were analyzed by SEM, XRD, FT-IR, DSC, TGA, DMTA and tensile mechanical tests. SEM showed that the presence of reactive groups on cellulose surface enhanced the compatibility,improving the fiber/matrix interfacial adhesion.FT-IR disclosed the occurrence of chemical reactions between the functionalized cellulose and polymer chains. The incorporation of fibers affected the crystallization behaviour and crystallinity of the polymer matrix. Composites with GMA modified cellulose displayed better compatibility, higher thermal and mechanical properties.Fil: Pracella, Mariano. Institute of Composite and Biomedical Materials; ItaliaFil: Minhaz-Ul Haque, M.. Universita Degli Studi Di Pisa; ItaliaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentin

Processing, compatibilization and properties of ternary composites of Mater-Bi with polyolefins and hemp fibres

Ternary composites of a biodegradable thermoplastic matrix, Mater-Bi (R) (MB), with various polyolefins (PP, HDPE and PS) and hemp fibres (H) were obtained by melt mixing and characterized by SEM, OM, DSC, TGA and tensile tests. The properties of composites were compared with those of MB/polyolefin and MB/H blends. Maleic anhydride functionalized polyolefins were employed as compatibilizers. Crystallization behaviour and morphology of the composites were found to be affected by the composition, phase dispersion and compatibilizer. Thermogravimetric analysis indicated that the thermal stability of the polyolefin phase and fibres was influenced by the composition and phase structure. A significant improvement of tensile modulus and strength was recorded for composites of MB with PE and PS as compared to MB/H composites. The results indicate that incorporation of polyolefins in the biodegradable matrix, compared to binary matrix/fibre system, may have significant advantages in terms of properties, processability and cost. (C) 2011 Elsevier Ltd. All rights reserved

Processing, compatibilization and properties of ternary composites of Mater-Bi with polyolefins and hemp fibres

Ternary composites of a biodegradable thermoplastic matrix, Mater-Bi (MB), with various polyolefins (PP, HDPE and PS) and hemp fibres (H) were obtained by melt mixing and characterized by SEM, OM, DSC, TGA and tensile tests. The properties of composites were compared with those of MB/polyolefin and MB/H blends. Maleic anhydride functionalized polyolefins were employed as compatibilizers. Crystallization behaviour and morphology of the composites were found to be affected by the composition, phase dispersion and compatibilizer. Thermogravimetric analysis indicated that the thermal stability of the polyolefin phase and fibres was influenced by the composition and phase structure. A significant improvement of tensile modulus and strength was recorded for composites of MB with PE and PS as compared to MB/H composites. The results indicate that incorporation of polyolefins in the biodegradable matrix, compared to binary matrix/fibre system, may have significant advantages in terms of properties, processability and cost

Fracture behaviour of biodegradable polymer/polyolefin-natural fibers ternary composites systems

In this work, blends of MaterBi K (MBK), a starch based biodegradable polymer with polypropylene (PP), high density polyethylene (HDPE) and polystyrene (PS) were prepared in an intensive mixer PP-g-MA; HDPE-g-MA and SEBS-g-MA were incorporated at 2 wt.% to corresponding matrix respectively in order to analyze the effect of compatibilizer amount on the morphology and final properties. The composites, with 20 wt.% of alkaline treated hemp fibers, were prepared by injection molding. Fracture and water absorption of matrices and composites were studied and the effect of each component was established. Blending of the MB matrix with PP and HDPE did not raise the Jc, with the exception of the MB-S3 blend which has a slight improvement in fracture energy. On the other hand, the fiber incorporation to blends improves significantly the Jc values for all samples compared with their respective matrices. The best result was obtained for the B8-S2 blend and the B8-P2 compatibilized blend. The water absorption of equilibrium was also studied, resulting from 0.3 % to 0.9 % for the polymer blends and raises from 5 % to 7 % for the fiber reinforced blends.Fil: Haque, Minhaz-Ul. International Islamic University; BangladeshFil: Stocchi, Ariel Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Pracella, Mariano. Università degli Studi di Pisa; Itali