Interference of biodegradable plastics in the polypropylene recycling process

[EN] Recycling polymers is common due to the need to reduce the environmental impact of these materials. Polypropylene (PP) is one of the polymers called commodities polymers' and it is commonly used in a wide variety of short-term applications such as food packaging and agricultural products. That is why a large amount of PP residues that can be recycled are generated every year. However, the current increasing introduction of biodegradable polymers in the food packaging industry can negatively affect the properties of recycled PP if those kinds of plastics are disposed with traditional plastics. For this reason, the influence that generates small amounts of biodegradable polymers such as polylactic acid (PLA), polyhydroxybutyrate (PHB) and thermoplastic starch (TPS) in the recycled PP were analyzed in this work. Thus, recycled PP was blended with biodegradables polymers by melt extrusion followed by injection moulding process to simulate the industrial conditions. Then, the obtained materials were evaluated by studding the changes on the thermal and mechanical performance. The results revealed that the vicat softening temperature is negatively affected by the presence of biodegradable polymers in recycled PP. Meanwhile, the melt flow index was negatively affected for PLA and PHB added blends. The mechanical properties were affected when more than 5 wt.% of biodegradable polymers were present. Moreover, structural changes were detected when biodegradable polymers were added to the recycled PP by means of FTIR, because of the characteristic bands of the carbonyl group (between the band 1700-1800 cm(-1)) appeared due to the presence of PLA, PHB or TPS. Thus, low amounts (lower than 5 wt.%) of biodegradable polymers can be introduced in the recycled PP process without affecting the overall performance of the final material intended for several applications, such as food packaging, agricultural films for farming and crop protection.This research was funded by Conselleria d'Educacio, Investigacio, Cultura y Esport de la Generalitat Valenciana, grant number APOSTD/2018/209.Samper, M.; Bertomeu, D.; Arrieta, MP.; Ferri, JM.; López-Martínez, J. (2018). Interference of biodegradable plastics in the polypropylene recycling process. Materials. 11(10):1-18. https://doi.org/10.3390/ma11101886S1181110Plastics Europe, Plastics—The Facts 2017https://www.plasticseurope.org/application/files/5715/1717/4180/Plastics_the_facts_2017_FINAL_for_website_one_page.pdfAres, A., Bouza, R., Pardo, S. G., Abad, M. J., & Barral, L. (2010). Rheological, Mechanical and Thermal Behaviour of Wood Polymer Composites Based on Recycled Polypropylene. Journal of Polymers and the Environment, 18(3), 318-325. doi:10.1007/s10924-010-0208-xBodar, C., Spijker, J., Lijzen, J., Waaijers-van der Loop, S., Luit, R., Heugens, E., … Traas, T. (2018). Risk management of hazardous substances in a circular economy. Journal of Environmental Management, 212, 108-114. doi:10.1016/j.jenvman.2018.02.014Alam, O., Wang, S., & Lu, W. (2018). Heavy metals dispersion during thermal treatment of plastic bags and its recovery. Journal of Environmental Management, 212, 367-374. doi:10.1016/j.jenvman.2018.02.034Bucci, D. Z., Tavares, L. B. B., & Sell, I. (2005). PHB packaging for the storage of food products. Polymer Testing, 24(5), 564-571. doi:10.1016/j.polymertesting.2005.02.008Siracusa, V., Rocculi, P., Romani, S., & Rosa, M. D. (2008). Biodegradable polymers for food packaging: a review. Trends in Food Science & Technology, 19(12), 634-643. doi:10.1016/j.tifs.2008.07.003Claro, P. I. C., Neto, A. R. S., Bibbo, A. C. C., Mattoso, L. H. C., Bastos, M. S. R., & Marconcini, J. M. (2016). Biodegradable Blends with Potential Use in Packaging: A Comparison of PLA/Chitosan and PLA/Cellulose Acetate Films. Journal of Polymers and the Environment, 24(4), 363-371. doi:10.1007/s10924-016-0785-4Avérous, L. (2004). Biodegradable Multiphase Systems Based on Plasticized Starch: A Review. Journal of Macromolecular Science, Part C: Polymer Reviews, 44(3), 231-274. doi:10.1081/mc-200029326Armentano, I., Fortunati, E., Burgos, N., Dominici, F., Luzi, F., Fiori, S., … Kenny, J. M. (2015). Processing and characterization of plasticized PLA/PHB blends for biodegradable multiphase systems. Express Polymer Letters, 9(7), 583-596. doi:10.3144/expresspolymlett.2015.55Arrieta, M. P., López, J., Rayón, E., & Jiménez, A. (2014). Disintegrability under composting conditions of plasticized PLA–PHB blends. Polymer Degradation and Stability, 108, 307-318. doi:10.1016/j.polymdegradstab.2014.01.034Garcia-Garcia, D., Ferri, J. M., Montanes, N., Lopez-Martinez, J., & Balart, R. (2016). Plasticization effects of epoxidized vegetable oils on mechanical properties of poly(3-hydroxybutyrate). Polymer International, 65(10), 1157-1164. doi:10.1002/pi.5164Russo, M. A. L., O’Sullivan, C., Rounsefell, B., Halley, P. J., Truss, R., & Clarke, W. P. (2009). The anaerobic degradability of thermoplastic starch: Polyvinyl alcohol blends: Potential biodegradable food packaging materials. Bioresource Technology, 100(5), 1705-1710. doi:10.1016/j.biortech.2008.09.026Neumann, I. A., Flores-Sahagun, T. H. S., & Ribeiro, A. M. (2017). Biodegradable poly (l-lactic acid) (PLLA) and PLLA-3-arm blend membranes: The use of PLLA-3-arm as a plasticizer. Polymer Testing, 60, 84-93. doi:10.1016/j.polymertesting.2017.03.013Khalid, S., Yu, L., Meng, L., Liu, H., Ali, A., & Chen, L. (2017). Poly(lactic acid)/starch composites: Effect of microstructure and morphology of starch granules on performance. Journal of Applied Polymer Science, 134(46), 45504. doi:10.1002/app.45504Arrieta, M., Samper, M., Aldas, M., & López, J. (2017). On the Use of PLA-PHB Blends for Sustainable Food Packaging Applications. Materials, 10(9), 1008. doi:10.3390/ma10091008Cosate de Andrade, M. F., Souza, P. M. S., Cavalett, O., & Morales, A. R. (2016). Life Cycle Assessment of Poly(Lactic Acid) (PLA): Comparison Between Chemical Recycling, Mechanical Recycling and Composting. Journal of Polymers and the Environment, 24(4), 372-384. doi:10.1007/s10924-016-0787-2Navarro, R., Ferrándiz, S., López, J., & Seguí, V. J. (2008). The influence of polyethylene in the mechanical recycling of polyethylene terephtalate. Journal of Materials Processing Technology, 195(1-3), 110-116. doi:10.1016/j.jmatprotec.2007.04.126Navarro, R., López, J., Parres, F., & Ferrándiz, S. (2011). Process behavior of compatible polymer blends. Journal of Applied Polymer Science, 124(3), 2485-2493. doi:10.1002/app.35260Sánchez-Jiménez, P. E., Pérez-Maqueda, L. A., Crespo-Amorós, J. E., López, J., Perejón, A., & Criado, J. M. (2010). Quantitative Characterization of Multicomponent Polymers by Sample-Controlled Thermal Analysis. Analytical Chemistry, 82(21), 8875-8880. doi:10.1021/ac101651gAlaerts, L., Augustinus, M., & Van Acker, K. (2018). Impact of Bio-Based Plastics on Current Recycling of Plastics. Sustainability, 10(5), 1487. doi:10.3390/su10051487Pivsa-Art, S., Kord-Sa-Ard, J., Pivsa-Art, W., Wongpajan, R., O-Charoen, N., Pavasupree, S., & Hamada, H. (2016). Effect of Compatibilizer on PLA/PP Blend for Injection Molding. Energy Procedia, 89, 353-360. doi:10.1016/j.egypro.2016.05.046Yoo, T. W., Yoon, H. G., Choi, S. J., Kim, M. S., Kim, Y. H., & Kim, W. N. (2010). Effects of compatibilizers on the mechanical properties and interfacial tension of polypropylene and poly(lactic acid) blends. Macromolecular Research, 18(6), 583-588. doi:10.1007/s13233-010-0613-yRosa, D. S., Guedes, C. G. F., & Carvalho, C. L. (2007). Processing and thermal, mechanical and morphological characterization of post-consumer polyolefins/thermoplastic starch blends. Journal of Materials Science, 42(2), 551-557. doi:10.1007/s10853-006-1049-9Sadi, R. K., Kurusu, R. S., Fechine, G. J. M., & Demarquette, N. R. (2011). Compatibilization of polypropylene/ poly(3-hydroxybutyrate) blends. Journal of Applied Polymer Science, 123(6), 3511-3519. doi:10.1002/app.34853Parres, F., Balart, R., López, J., & García, D. (2008). Changes in the mechanical and thermal properties of high impact polystyrene (HIPS) in the presence of low polypropylene (PP) contents. Journal of Materials Science, 43(9), 3203-3209. doi:10.1007/s10853-008-2555-8Fekete, E., Földes, E., & Pukánszky, B. (2005). Effect of molecular interactions on the miscibility and structure of polymer blends. European Polymer Journal, 41(4), 727-736. doi:10.1016/j.eurpolymj.2004.10.038Macaúbas, P. H. P., & Demarquette, N. R. (2002). Time-temperature superposition principle applicability for blends formed of immiscible polymers. Polymer Engineering & Science, 42(7), 1509-1519. doi:10.1002/pen.11047Polymer Properties Databasehttps://polymerdatabase.com/polymer%20classes/Intro.htmlGoonoo, N., Bhaw-Luximon, A., & Jhurry, D. (2015). Biodegradable polymer blends: miscibility, physicochemical properties and biological response of scaffolds. Polymer International, 64(10), 1289-1302. doi:10.1002/pi.4937Arrieta, M. P., López, J., López, D., Kenny, J. M., & Peponi, L. (2015). Development of flexible materials based on plasticized electrospun PLA–PHB blends: Structural, thermal, mechanical and disintegration properties. European Polymer Journal, 73, 433-446. doi:10.1016/j.eurpolymj.2015.10.036Ferri, J. M., Garcia-Garcia, D., Carbonell-Verdu, A., Fenollar, O., & Balart, R. (2017). Poly(lactic acid) formulations with improved toughness by physical blending with thermoplastic starch. Journal of Applied Polymer Science, 135(4), 45751. doi:10.1002/app.45751Sessini, V., Arrieta, M. P., Kenny, J. M., & Peponi, L. (2016). Processing of edible films based on nanoreinforced gelatinized starch. Polymer Degradation and Stability, 132, 157-168. doi:10.1016/j.polymdegradstab.2016.02.026Fan, Y., Nishida, H., Shirai, Y., Tokiwa, Y., & Endo, T. (2004). Thermal degradation behaviour of poly(lactic acid) stereocomplex. Polymer Degradation and Stability, 86(2), 197-208. doi:10.1016/j.polymdegradstab.2004.03.001Sessini, V., Raquez, J.-M., Lourdin, D., Maigret, J.-E., Kenny, J. M., Dubois, P., & Peponi, L. (2017). Humidity-Activated Shape Memory Effects on Thermoplastic Starch/EVA Blends and Their Compatibilized Nanocomposites. Macromolecular Chemistry and Physics, 218(24), 1700388. doi:10.1002/macp.201700388Gerard, T., Budtova, T., Podshivalov, A., & Bronnikov, S. (2014). Polylactide/poly(hydroxybutyrate-co-hydroxyvalerate) blends: Morphology and mechanical properties. Express Polymer Letters, 8(8), 609-617. doi:10.3144/expresspolymlett.2014.64Lanzotti, A., Grasso, M., Staiano, G., & Martorelli, M. (2015). The impact of process parameters on mechanical properties of parts fabricated in PLA with an open-source 3-D printer. Rapid Prototyping Journal, 21(5), 604-617. doi:10.1108/rpj-09-2014-0135Arrieta, M. P., López, J., Hernández, A., & Rayón, E. (2014). Ternary PLA–PHB–Limonene blends intended for biodegradable food packaging applications. European Polymer Journal, 50, 255-270. doi:10.1016/j.eurpolymj.2013.11.009Du, Y.-L., Cao, Y., Lu, F., Li, F., Cao, Y., Wang, X.-L., & Wang, Y.-Z. (2008). Biodegradation behaviors of thermoplastic starch (TPS) and thermoplastic dialdehyde starch (TPDAS) under controlled composting conditions. Polymer Testing, 27(8), 924-930. doi:10.1016/j.polymertesting.2008.08.00

Sexuality throughout all the stages of pregnancy: experiences of expectant mothers

Objective: To explore and understand the sexual experiences of expectant mothers during their pregnancy. Methods: The study was carried out in two healthcare centers in the Almería Health District, in southern Spain. The participants included pregnant women who received prenatal care and/or maternity education. The inclusion criteria were being pregnant, maintaining sexual activity and agreeing to participate in the study. The exclusion criteria were having limitations on sexual activity by medical prescription. The sample consisted of 15 expectant women selected using a convenience sample, of which 5 took part in a focus group (FG) and 10 in in-depth interviews (IDI). Data was collected between the months of June and December 2016. Participants were contacted by the main researcher and an appointment was made to carry out the FGs or the IDIs. Results: Three main categories emerged: False beliefs and a holistic approach to sexuality during pregnancy, which is related to the concept of sexuality, false beliefs, and limited sexual counseling during pregnancy. Limitations: From fear at the beginning to physical diffi culty at the end, referring to the fluctuations in sexual desire as well as the physical changes that limit sexual activity. Adapting to changes: safe practices and satisfaction with one’s body image, which encompasses concerns about the risks and the relationship between body image and self-esteem. Conclusion: A lack of sexual counseling during pregnancy leads to the creation of false beliefs, which, together with physical changes, concerns about the risk, and fl uctuations in sexual desire and interest, bring about a decrease in sexual activity. But sexuality remains an important aspect of pregnancy, toward which the participants must adopt a broader approach, not limited to intercourse, and adopt sexual practices that are adapted to the physical and emotional changes that happen during this time

Independent determination of the two gaps by directional point-contact spectroscopy in MgB_2 single crystals

Directional point-contact spectroscopy measurements were performed for the first time in state-of-the-art MgB_2 single crystals. The selective suppression of the superconductivity in the "pi" band by means of a suitable magnetic field allowed separating the partial contribution of each band to the total point-contact conductance. By fitting the partial conductance curves sigma_sigma(V) and sigma_pi(V), we got an independent determination of the two gaps, Delta_sigma and Delta_pi, with a strong reduction of the experimental uncertainty. Their temperature dependence was found to agree well with the predictions of the two-band models for MgB_2.Comment: 6 pages, 4 eps figures. References added, abstract rewritten, text slightly changed. Proceedings of the BOROMAG Conference, June 17-19, Genoa, Ital

Drag estimation on wedge-shaped protuberances in high-speed flows

A semi-empirical method is developed to estimate drag on wedge-shaped projections in hypersonic flow. Force balance measurements from gun tunnel tests directly measure total drag on blunt wedges, where the boundary layer and the entropy layer are weakly coupled. Detailed flowfield analysis from numerical simulations provides estimated locations of peak pressure ratio and skin friction. Schlieren images are used for detecting incipient separation in incoming flows with laminar and turbulent boundary layers. Test results indicate the presence of local hotspots at reattachment points of strong detached shocks on the wedge compression ramp, and of primary and secondary vortical structures around lateral faces. Total drag is found to decrease with decreasing bluntness but increasing slenderness in wedges tend to increase skin friction drag

Thermal and mechanical characterization of epoxy resins (ELO and ESO) cured with anhydrides

In this work we have developed polymeric materials from epoxidized vegetable oils in order to obtain materials with excellent mechanical properties for use as green matrix composites. Epoxidized soybean oil (ESO), epoxidized linseed oil (ELO) and different mixtures of the two oils were used to produce the polymers. Phthalic anhydride (17 mol%) and maleic anhydride (83 mol%) which has a eutectic reaction temperature of 48 °C were used as crosslinking agents while benzyl dimethyl amine (BDMA) and ethylene glycol were used as the catalyst and initiator, respectively. The results showed that samples 100ELO and 80ELO20ESO could be used as a matrix in green composites because they demonstrated good mechanical properties. © 2012 AOCS (outside the USA).This work is part of the project IPT-310000-2010-037,''ECOTEXCOMP: Research and development of textile structures useful as reinforcement of composite materials with marked ecological character'' funded by the "Ministerio de Ciencia e Innovacion", with financial aid of 189,540.20 EUR, within the "Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica 2008-2011" and funded by the European Union through FEDER funds, Technology Fund 2007-2013, Operational Programme on R + D + i for and on behalf of the companies.Samper Madrigal, MD.; Fombuena Borrás, V.; Boronat Vitoria, T.; García Sanoguera, D.; Balart Gimeno, RA. (2012). Thermal and mechanical characterization of epoxy resins (ELO and ESO) cured with anhydrides. Journal of the American Oil Chemists' Society. 89(8):1521-1528. https://doi.org/10.1007/s11746-012-2041-yS15211528898Averous L (2004) Biodegradable multiphase systems based on plasticized starch: a review. J Macromol Sci Polym Rev C44:231–274Bledzki AK, Jaszkiewicz A (2010) Mechanical performance of biocomposites based on PLA and PHBV reinforced with natural fibres—a comparative study to PP. Compos Sci Technol 70:1687–1696Raquez JM, Deleglise M, Lacrampe MF, Krawczak P (2010) Thermosetting (bio)materials derived from renewable resources: a critical review. Prog Polym Sci 35:487–509Charlet K, Jernot JP, Gomina M, Bizet L, Breard J (2010) Mechanical properties of flax fibers and of the derived unidirectional composites. J Compos Mater 44:2887–2896Barreto ACH, Esmeraldo MA, Rosa DS, Fechine PBA, Mazzetto SE (2010) Cardanol biocomposites reinforced with jute fiber: microstructure, biodegradability, and mechanical properties. Polym Compos 31:1928–1937Thakur VK, Singha AS (2010) Physico-chemical and mechanical characterization of natural fibre reinforced polymer composites. Iran Polym J 19:3–16Schmitz WR, Wallace JG (1954) Epoxidation of methyl oleate with hydrogen peroxide. J Am Oil Chem Soc 31:363–365La Scala J, Wool RP (2002) Effect of FA composition on epoxidation kinetics of TAG. J Am Oil Chem Soc 79:373–378de Espinosa LM, Ronda JC, Galia M, Cadiz V (2008) A new enone-containing triglyceride derivative as precursor of thermosets from renewable resources. J Polym Sci Pol Chem 46:6843–6850Gerbase AE, Petzhold CL, Costa APO (2002) Dynamic mechanical and thermal behavior of epoxy resins based on soybean oil. J Am Oil Chem Soc 79:797–802Boquillon N, Fringant C (2000) Polymer networks derived from curing of epoxidised linseed oil: influence of different catalysts and anhydride hardeners. Polymer 41:8603–8613Montserrat S, Flaque C, Calafell M, Andreu G, Malek J (1995) Influence of the accelerator concentration on the curing reaction of an epoxy-anhydride system. Thermochim Acta 269:213–229Zacharuk M, Becker D, Coelho LAF, Pezzin SH (2011) Study of the reaction between polyethylene glycol and epoxy resins using N,N-dimethylbenzylamine as catalyst. Polimeros 21:73–77Lozada Z, Suppes GJ, Tu YC, Hsieh FH (2009) Soy-based polyols from oxirane ring opening by alcoholysis reaction. J Appl Polym Sci 113:2552–256

Polyphosphate degradation by Nudt3-Zn²⁺ mediates oxidative stress response

Polyphosphate (polyP) is a polymer of hundreds of phosphate residues present in all organisms. In mammals, polyP is involved in crucial physiological processes, including coagulation, inflammation, and stress response. However, after decades of research, the metabolic enzymes are still unknown. Here, we purify and identify Nudt3, a NUDIX family member, as the enzyme responsible for polyP phosphatase activity in mammalian cells. We show that Nudt3 shifts its substrate specificity depending on the cation; specifically, Nudt3 is active on polyP when Zn2+ is present. Nudt3 has in vivo polyP phosphatase activity in human cells, and importantly, we show that cells with altered polyP levels by modifying Nudt3 protein amount present reduced viability upon oxidative stress and increased DNA damage, suggesting that polyP and Nudt3 play a role in oxidative stress protection. Finally, we show that Nudt3 is involved in the early stages of embryo development in zebrafish

The Dependence of the Superconducting Transition Temperature of Organic Molecular Crystals on Intrinsically Non-Magnetic Disorder: a Signature of either Unconventional Superconductivity or Novel Local Magnetic Moment Formation

We give a theoretical analysis of published experimental studies of the effects of impurities and disorder on the superconducting transition temperature, T_c, of the organic molecular crystals kappa-ET_2X and beta-ET_2X (where ET is bis(ethylenedithio)tetrathiafulvalene and X is an anion eg I_3). The Abrikosov-Gorkov (AG) formula describes the suppression of T_c both by magnetic impurities in singlet superconductors, including s-wave superconductors and by non-magnetic impurities in a non-s-wave superconductor. We show that various sources of disorder lead to the suppression of T_c as described by the AG formula. This is confirmed by the excellent fit to the data, the fact that these materials are in the clean limit and the excellent agreement between the value of the interlayer hopping integral, t_perp, calculated from this fit and the value of t_perp found from angular-dependant magnetoresistance and quantum oscillation experiments. If the disorder is, as seems most likely, non-magnetic then the pairing state cannot be s-wave. We show that the cooling rate dependence of the magnetisation is inconsistent with paramagnetic impurities. Triplet pairing is ruled out by several experiments. If the disorder is non-magnetic then this implies that l>=2, in which case Occam's razor suggests that d-wave pairing is realised. Given the proximity of these materials to an antiferromagnetic Mott transition, it is possible that the disorder leads to the formation of local magnetic moments via some novel mechanism. Thus we conclude that either kappa-ET_2X and beta-ET_2X are d-wave superconductors or else they display a novel mechanism for the formation of localised moments. We suggest systematic experiments to differentiate between these scenarios.Comment: 18 pages, 5 figure