Research Activity

The PolymerApps Group is constantly growing in size and experience, exhibiting research activity mainly in the following fields:

•  Polyamides/Polyesters Science and Technology. Green Solid State Polycondensation Processes

•  Migration of Additives from Plastics. Packaging/”Nano”-Packaging

•  Nanotechnology and Polymers. Nanocatalysis. Nanocomposites. Flame Retardancy

•  Waste Management and Recycling of Plastics. Recycling and Migration. Recycling of Polymeric Composite Materials

Click on each field for a detailed description of our activity and indicative publications. For a full list of our group's refereed papers, click here.

Polyamides/Polyesters Science and Technology. Green Solid State Polycondensation Processes

 

Polyamides/Polyesters can be produced through a green polycondensation process. The conventional solution to/or melt polymerization techniques stop at a low or medium molecular weight product, due to problems arising from severe increase of the melt viscosity and operating temperatures. Higher molecular weights may be reached by Solid State Polymerization (SSP) at temperatures between the glass transition and the onset of melting. Polycondensation progresses through chain end reactions in the amorphous phase of the semicrystalline polymer, which in most cases is in the form of pellets, flakes or powder; reaction by-products are removed by application of vacuum or through convection caused by passing an inert gas. The application of SSP presents many advantages in the quality of the material and the simplicity of the process, due to the low SSP operating temperatures. In that respect, the main objective of the group’s research activities is to optimize the production of any kind of condensation polymers/biopolymers. Recently the focus is on High Temperature Polymers (e.g. semi-aromatic polyamides) and Biopolyesters (e.g. PLA, PBS) for packaging applications, while combination of Enzymatic Prepolymerization and Bulk Post Polymerization is attempted towards the development of sustainable polymers’ production methods.

Indicative publications:

• Pfaendner R, Fink J, Simon D, Papaspyrides C, Vougiouka S. Process for the preparation of polyamides in the presence of a phosphonate. (Ciba Specialty Chemicals Lampertheim GmbH) WO2007/006647, 2007, pp.36.

• Vouyiouka S, Papaspyrides C, Weber J, Marks D. Solid state post-polymerization of PA 6,6: Τhe effect of sodium 5-sulfoisophthalic acid. Polymer 2007; 48(17): 4982-4989.

• Papaspyrides C, Vouyiouka S, Εditors. Solid state polymerization. NJ: John Wiley & Sons, Inc. 2009 (Invited) pp.1-294.

• Boussia A, Vouyiouka S, Porfiris A, Papaspyrides C. Long aliphatic-segment polyamides: Salt preparation and subsequent anhydrous polymerization. Macromol. Mater. Eng. 2010; 295(9):812-821.

• Filgueiras V, Vouyiouka S, Papaspyrides C, Lima E, Pinto J. Solid state polymerization of poly(ethylene terephthalate): The effect of water vapor at low content in the carrier gas. Macromol. Mater. Eng. 2011; 296:113-121.

• Vouyiouka S, Papaspyrides C. Solid state polymerization. Encyclopedia of Polymer Science and Technology, 4th edition. NJ: John Wiley & Sons, Inc. 2011 (Invited) pp.1-32.

• Vouyiouka S, Filgueiras V, Papaspyrides C, Pinto J, Lima E. Morphological changes of poly(ethylene terephthalate-co-isophthalate) during solid state polymerization. J. Appl.Polym. Sci. 2012; 124(6):4457-4465.

• Vouyiouka S, Papaspyrides C. Mechanistic aspects of solid state polycondensation. In: Matyjaszewski K, Moeller M, editors. Comprehensive Polymer Science: Vol.4 Elsevier. 2012 (Invited) pp.857-874.

• Vouyiouka S, Topakas E, Katsini A, Papaspyrides C, Christakopoulos P. A green route for the preparation of aliphatic polyesters via lipase-catalyzed prepolymerization and low-temperature post polymerization. Macromol. Mater. Eng. 2013;298(6):679-689.

• Vouyiouka S, Theodoulou P, Symeonidou A, Papaspyrides C, Pfaendner R. Solid state polymerization of poly(lactic acid): some fundamental parameters. Polym. Degrad. Stab., 2013, 98(12), 2473-2481 (invited)

 

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-  Migration of Additives from Plastics. Packaging/”Nano”-Packaging

 

The research is focused on relating migration with characteristic polymer properties, such as: nature of the materials involved, molecular weight, crystallinity and previous history of the polymer sample, temperature (in relation with Tg), conditions of contact and surface crosslinking. Emphasis is always given on the experimental setup considering both solid/liquid and solid/solid systems while recently the interest has been focused on detecting migration at very low levels by using also the so called “Fluorescence Recovery After Photobleaching” (FRAP) technique adapted from biological studies. Migration of nanosized materials is also considered since nanotoxicology aspects become rapidly important for public health.

 

Indicative publications

• Hatzigrigoriou N, Papaspyrides C, Joly C, Dole P. The effect of migrant size on diffusion in dry and hydrated polyamide 6.   J. Agr. Food Chem. 2010;58(15):8667-867.

• Hatzigrigoriou N, Papaspyrides C, Joly C, Pinte J, Dole P. Diffusion studies through fluorescence recovery after photobleaching in hydrated polyamides. Polym. Eng. Sci. 2011;51(3):532-541.

• Hatzigrigoriou N, Papaspyrides C. Nanotechnology on plastic food contact materials. J. Appl. Polym. Sci. 2011; 122(6):3720 – 3739.

• Hatzigrigoriou N, Vouyiouka S, Papaspyrides C. Temperature-humidity superposition in diffusion phenomena through polyamidic materials. J. Appl. Polym. Sci. 2012;125(4):2814-2823.

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-  Nanotechnology and Polymers. Nanocatalysis. Nanocomposites. Flame Retardancy

A very popular route to advanced polymer properties is recently provided by nanotechnology. Polymer-clay nanocomposites comprise a quite new class of filled polymers, with tailor-made properties suitable for specialty applications. The concept of the group’s activities here lies in two axes: in the first one, the objective is to investigate nanoparticles influence on solid state polymerization processes and to develop multifunctional organoclay-based catalytic systems. In the second axis, focus is given on polymer properties optimization in respect to flame retardancy. The synergistic action of organoclays and organic/inorganic halogen-free flame retardants is assessed in order to develop novel, efficient and “green” flame retardants and to apply them in lightweight structures and prototype articles (plastics, composites and textiles) for a variety of applications, serving as a proof of the commercial viability of the new FRs.

Currently, the group activities are focused also on encapsulation of active ingredients in biodegradable polymer nanoparticles, a technology which has tremendous potential in the pharmaceutical and cosmetics industry as it can enhance penetration for a better efficacy, help target some specific cells in order to deliver better, protect unstable ingredients and improve the bioactivity of the encapsulated compounds.

Indicative publications:

• Kiliaris P, Papaspyrides C, Pfaendner R. Polyamide 6 filled with melamine cyanurate and layered silicates: Evaluation of flame retardancy and physical properties. Macromol. Mat. Eng. 2008;293: 740-751.

• Pavlidou S, Papaspyrides C.  A review on polymer layered silicate nanocomposites. Prog. Polym. Sci. 2008; 33:1119-1198.

• Kiliaris P, Papaspyrides C, Pfaendner R. Influence of accelerated aging on clay reinforced polyamide 6. Polym. Deg. Stab. 2009;94:389-396.

• Kiliaris P, Papaspyrides C. Polymer/layered silicate nanocomposites: An overview of flame retardancy. Prog. Polym. Sci. 2010;35:902-958.

•  Pfaendner R, Papaspyrides C, Kiliaris P. Layered silicate flame retardant compositions. BASF SE (Inc.) Pat. No. WO2010/069835 A1, June 24, 2010.

• Boussia A, Damianou Ch, Vouyiouka S, Papaspyrides C. I Potential in-situ preparation of aliphatic polyamide based nanocomposites: Τhe organoclay-polyamide salt interaction. J. Appl. Polym. Sci. 2010;116(6):3291-3302.

• Boussia A, Konstantakopoulou M, Vouyiouka S, Papaspyrides C. Nanocatalysis in polyamide 6.6 solid state polymerization. Macromol. Mater. Eng. 2011; 296: 168-177.

• Kiliaris P, Papaspyrides C, Pfaendner R. Polyamide 6 compositions with melamine polyphosphate and layered silicates: Evaluation of flame retardancy and physical properties. Macromol. Mat. Eng. 2011;296(7):617-629.

• Boussia A, Vouyiouka S, Papaspyrides C. Polyamide nanocomposites by in-situ polymerization. Chapter 2. In: V. Mittal, editor. In-situ synthesis of polymer nanocomposites. Weinheim: Wiley VCH Verlag GmbH & Co. KGaA. 2012 (Invited) pp.27-51.

• Boussia A, Konstantakopoulou M, Vouyiouka S, Papaspyrides C. Catalytic performance and nanoclay effects on post solid state polyamidation: the case of polyamide 6.6 nanocomposites. J. Appl. Polym. Sci. 2012;125(1):320-326.

• Boussia A, Vouyiouka S, Papaspyrides C. Applying the traditional solution-melt polymerization for the in-situ intercalation of polyamide 6.6-clay nanocomposites. Macromol. Mater. Eng. 2012;297(1):68-74.

• Kiliaris P, Papaspyrides C, Xalter R, Pfaendner R. Study on the properties of polyamide 6 blended with melamine polyphosphate and layered silicates. Polym. Degrad. Stab. 2012; 97(7):1215-1222.

• Papaspyrides C, Kiliaris P, Editors. Green polymer flame retardants: A comprehensive guide to additives and their applications. Elsevier, 2014.

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-  Waste Management and Recycling of Plastics. Recycling and Migration. Recycling of Polymeric Composite Materials

Research on the “Remelting/Restabilization Technique”, “Reactive Extrusion” and the “Dissolution/ Reprecipitation Route”. In the first technique, the incorporation of processing, thermal and light stabilizers in the post-consumed polymer comprises an effective method to minimize the decomposition effects during the reprocessing stage and reuse, while in the second one the incorporation of appropriate chain extenders permits enhancement of molecular weight, in cases where this is a prerequisite for following reprocessing. On the other hand, the dissolution/reprecipitation technique has been studied, aiming at the production of recyclates exhibiting similar properties with the virgin material. It is a multi-stage process comprising the dissolution of the plastic waste in an appropriate solvent (so that polymers are selectively dissolved) and then its reprecipitation by using a non-solvent. An additional important research field comprises the use of recycled plastics in packaging and introducing the term of functional barrier. Finally, evaluations on the so called “Super-Clean Recycling Process”, widely applied for used PET bottles closed loop recycling, are based exclusively on the aforementioned SSP technology.

Indicative publications

• Poulakis J, Papaspyrides C. The dissolution/reprecipitation route for the recycling of LDPE: The effect of polymer concentration and sample history. Polymer Recycling 1995; 1(2):125-131.

• Papaspyrides C, Poulakis J. Recycling, Plastics. In: The Polymeric Materials Encyclopedia (ed. J.C. Salamone), CRC Press, Inc., 1996, 7403-7419.

• Kartalis C, Papaspyrides C, Pfaendner R, Hoffmann K, Herbst H. Mechanical recycling of post-used HDPE crates using the restabilization technique. Part 1: Influence of reprocessing. J. Appl. Polym. Sci. 1999;75:1775-1785.

• Papaspyrides C, Kartalis C. A model study for the recovery of polyamides using the dissolution/reprecipitation technique. Polym. Eng. Sci. 2000;40(4):979-984.

• Kartalis C, Papaspyrides C, Pfaendner R, Hoffmann K, Herbst H. Recycled and restabilized HDPE bottle crates: Retention of critical properties after heat aging. Polym. Eng. Sci. 2001; 41(5):771-781.

• Kartalis C, Papaspyrides C, Pfaendner R, Hoffmann K, Herbst H. Closed loop recycling of bottle crates using the restabilization technique. Macrom. Mat. Eng. 2003;88(2): 124-136.

• Feigenbaum A, Dole P, Aucejo S, Dainelli D, C. de la Cruz Garcia, Hankemeier T, N’Gono Y, Papaspyrides C, Paseiro P, Pastorelli S, Pavlidou S, Pennarun P.Y, Saillard P, Vidal L, Vitrac O, Voultzatis Y. Functional barriers: Properties and evaluation. Food Additives and Contaminants, 2005; 22(10):956-967.

• Papaspyrides C, Voultzatis Y, Pavlidou S, Tsenoglou C, Dole P, Feigenbaum A, Paseiro P, Pastorelli S, C. de la Cruz Garcia, Hankemeier T, Aucejo S. New experimental procedure for incorporation of model contaminants in polymer hosts. Progress in Rubber, Plastics and Recycling Technology, 2005;21(4):243-260.

• Dole P, Feigenbaum A, C. de la Cruz Garcia, Pastorelli S, Voultzatis Y, Aucejo S, Saillard P, Papaspyrides C. Typical diffusion behaviour in packaging polymers: Application to functional barriers. Food Additives and Contaminants 2006;23(2):202-211.

• Kiliaris P, Papaspyrides C, Pfaendner R. The reactive extrusion route for closed-loop recycling of poly(ethylene terephthalate). J. Appl. Polym. Sci. 2007;104:1671-1678.

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