Konrad Walkowiak
@zut.edu.pl
Department of Materials Technologies
West Pomeranian University of Technology,
Scopus Publications
Scopus Publications
Sandra Paszkiewicz, Konrad Walkowiak, Izabela Irska, Zbigniew Rozwadowski, and Jerzy Dryzek
Wiley
AbstractTwo series of biobased poly(ether‐ester)s comprised of poly(hexamethylene 2,5‐furandicarboxylate) (PHF) as the rigid segments and biopolytetrahydrofuran (pTHF) with different molecular masses (1000 and 2000 g/mol) as the flexible segments were synthesized employing polycondensation in the molten state. The study mainly focuses on comparing these two series in terms of the length of the flexible segment. The content of pTHF segments in the copolymer chains varied from 25 to 75 wt.%. The molecular structure and composition, phase structure, and thermal and mechanical properties were characterized by nuclear magnetic resonance (1H NMR) and Fourier‐transformed infrared (FTIR) spectroscopies, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and positron annihilation lifetime spectroscopy (PALS). In addition, mechanical performance and thermo‐oxidative and thermal stability have been investigated. Moreover, cyclic tensile properties were studied to evaluate the elastic properties. 1H NMR and FTIR spectroscopies demonstrate that the syntheses were correctly carried out, which made it possible to obtain the desired compositions of the block copolymers with high molecular masses. The decrease in Tm1, Tc1, and XcPHF values was visible, along with the increase in the flexible segment content. Moreover, the characteristic properties measured by PALS and the values of temperatures designated from TGA (inert and oxidizing atmosphere) did not vary between copolymer series PHF‐b‐F‐pTHF1000 and PHF‐b‐F‐pTHF2000. In turn, along with an increase in flexible segment content and the length of the pTHF, the values of tensile modulus, stress at break, and hardness decrease, while the value of elongation at break increases.
Sandra Paszkiewicz, Grzegorz Kramek, Konrad Walkowiak, Izabela Irska, Elżbieta Piesowicz, Monika Rzonsowska, Beata Dudziec, and Mateusz Barczewski
LUKASIEWICZ Research Network - Industrial Chemistry Research Institute
The influence of the addition of tetrafunctional double-decker silsesquioxanes (DDSQ-ether-4OH) on the compatibility, thermal and mechanical properties of polylactide and epoxidized natural rubber (PLA/ENR) vulcanizates was investigated. The apparent cross-linking density and thermal stability of PLA/ENR vulcanizates were also determined. The FTIR analysis confirmed the compatibilizing effect of DDSQ-ether-4OH and the formation of the PLA-g-ENR copolymer. A strong effect of ENR content and DDSQ-ether-4OH addition on the thermal and mechanical properties of the obtained vulcanizates was demonstrated.
Paulina Bednarczyk, Konrad Walkowiak, and Izabela Irska
MDPI AG
Recently, photocurable coatings are being used frequently. However, it is worth mentioning that the use of photopolymerization has its drawbacks, especially in the case of curing coatings on three-dimensional surfaces and in places that are difficult to access for UV radiation. However, it is possible to develop a system in which UV technology and thermal methods for curing coatings can be combined. Moreover, the obtained resins are derived from low-viscosity epoxy resins or diglycidyl ethers, making them an ideal building material for photopolymerization-based three-dimensional printing techniques. Due to the need to improve this method, a series of epoxy (meth)acrylates containing both epoxy and (meth)acrylate groups were obtained via the addition of acrylic or methacrylic acid to epoxy resin, diglycydylether of bisphenol A epoxy resin (DGEBA), cyclohexane dimethanol diglycidyl ether (CHDMDE) and neopentyl glycol diglycidyl ether (NPDE). The structures of the synthesized copolymers were confirmed through spectroscopic analysis (FTIR) and studied regarding their nonvolatile matter content (NV) and acid values (PAVs), as well as their epoxy equivalent values (EEs). Due to the presence of both epoxy and double carbon–carbon pendant groups, two distinct mechanisms can be applied: cationic and radical. Hence, the obtained resins can be cured using UV radiation with thermally appropriate conditions and initiators. This type of method can be used as a solution to many problems currently encountered in using UV technology, such as failure to cure coatings in underexposed areas as well as deformation of coatings. Synthesized epoxy (meth)acrylate prepolymers were employed to formulate photocurable coating compositions. Furthermore, the curing process and properties of cured coatings were investigated regarding some structural factors and parameters. Among the synthesized materials, the most promising are those based on epoxy resin, characterized by their high glass transition temperature values and satisfactory functional properties.
Sandra Paszkiewicz, Paweł Lesiak, Konrad Walkowiak, Izabela Irska, Karol Miądlicki, Marcin Królikowski, Elżbieta Piesowicz, and Paweł Figiel
MDPI AG
Regarding the dynamic development of 3D printing technology, as well as its application in a growing part of industries, i.e., in the automotive industry, construction industry, medical industry, etc., there is a notable opportunity for its application in producing dental implants, which presents a promising alternative to traditional implant manufacturing methods. The medical industry is very restrictive regarding the applied materials, and it is necessary to use materials that exhibit very good mechanical and thermal parameters, show clinical indifference and biocompatibility, are non-allergenic and non-cancerous, and are likely to sterilize. Such materials are poly(aryl-ether-ketone)s (PAEK)s, mainly poly(ether-ether-ketone) (PEEK) and poly(ether-ketone-ketone) (PEKK), that are found to be high-performance polymers and can be defined as materials that retain their functionality even in extreme conditions. In the present paper, two types of PEEKs and PEKK were compared regarding their structural, mechanical, and thermal properties along with the biological activity toward selected strains. The tested samples were obtained with Fused Deposition Modeling (FDM) technology. The PEKK, after heat treatment, exhibits the most promising mechanical properties as well as less bacterial adhesion on its surface when compared to both PEEKs. Consequently, among the evaluated materials, PEKK after heat treatment stands out as the optimal selection for a dental prosthesis.
Konrad Walkowiak, Sandra Paszkiewicz, Izabela Irska, Agnieszka Kochmanska, Kamil Dydek, Anna Boczkowska, Rafal Stanik, Mike Gude, Amelia Linares, and Tiberio Ezquerra
Wiley
Sandra Paszkiewicz, Konrad Walkowiak, Izabela Irska, Agata Zubkiewicz, Paweł Figiel, Krzysztof Gorący, and Mirosława El Fray
Elsevier BV
Sandra Paszkiewicz, Konrad Walkowiak, Izabela Irska, Sonia Mechowska, Katarzyna Stankiewicz, Agata Zubkiewicz, Elżbieta Piesowicz, and Piotr Miadlicki
Springer Science and Business Media LLC
AbstractIn recent years, there has been a trend toward replacing petrochemical raw materials with so-called “bio” plastics, i.e. plastics from renewable sources. Herein, the susceptibility of degradation in the compost heap of three types of packaging polyesters, by means of PET and biobased PEF and PLA, with other thermoplastic polyesters with more methylene groups (three and six) bio—(PTF and PHF, respectively) and petrochemically-based (PTT and PHT, respectively) has been studied. Two series of polymer materials based on ethylene, propylene, and hexamethylene glycols and two diesters (dimethyl terephthalate and dimethyl 2,5-furandicarboxylate) were thus obtained and compared with “double green” PLA. Moreover, the assessment of the influence of the subsequent processing cycle (injection moulding) on the utilitarian properties of these materials, constitutes the analogy to the subsequent recycling cycle. The susceptibility to degradation was assessed in the context of changes in the structure (analyzed by FTIR and DSC), intrinsic viscosity, and mechanical performance. In addition, chromatographic analysis of the solutions of the analyzed samples in methanol was carried out in order to determine whether and what low-molecular compounds were released from the analyzed polyesters. It has been shown that furan-based polyesters have great potential to replace materials based on dimethyl terephthalate-based polyesters.
Sandra Paszkiewicz, Izabela Irska, Agata Zubkiewicz, Konrad Walkowiak, Zbigniew Rozwadowski, Jerzy Dryzek, Amelia Linares, Aurora Nogales, and Tiberio A. Ezquerra
Royal Society of Chemistry (RSC)
A fully plant-based sustainable copolyester series, poly(butylene 2,5-furandicarboxylate)-block-poly(caprolactone)s, were successfully synthesized by melt polycondensation combining butylene 2,5-furandicarboxylate with polycaprolactone diol at different weight ratios.
Sandra Paszkiewicz
Wydawnictwo SIGMA-NOT, sp. z.o.o.
Konrad Walkowiak, Izabela Irska, and Sandra Paszkiewicz
Elsevier BV
Agata Zubkiewicz, Izabela Irska, Konrad Walkowiak, Jerzy Dryzek, and Sandra Paszkiewicz
Department of Polymer Engineering, Scientific Society of Mechanical Engineering
Konrad Walkowiak, Izabela Irska, Agata Zubkiewicz, Jerzy Dryzek, and Sandra Paszkiewicz
MDPI AG
A series of poly(ester amide)s based on dimethyl furan 2,5-dicarboxylate (DMFDC), 1,3-propanediol (PDO), 1,6-hexylene glycol (HDO), and 1,3-diaminopropane (DAP) were synthesized via two-step melt polycondensation. The phase transition temperatures and structure of the polymers were studied by differential scanning calorimetry (DSC). The positron annihilation lifetime spectroscopy (PALS) measurement was carried out to investigate the free volume. In addition, the mechanical properties of two series of poly(ester amide)s were analyzed. The increase in the number of methylene groups in the polymer backbone resulted in a decrease in the values of the transition temperatures. Depending on the number of methylene groups and the content of the poly(propylene furanamide) (PPAF), both semi-crystalline and amorphous copolymers were obtained. The free volume value increased with a greater number of methylene groups in the polymer backbone. Moreover, with a lower number of methylene groups, the value of the Young modulus and stress at break increased.
Agata Zubkiewicz, Izabela Irska, Piotr Miadlicki, Konrad Walkowiak, Zbigniew Rozwadowski, and Sandra Paszkiewicz
Springer Science and Business Media LLC
AbstractIn this work, new bio-based copoly(ester amide)s were synthesized by a two-step melt polycondensation process, using 2,5-furanedicarboxylic acid dimethyl ester (DMFDC), 1,3-propanediol (PDO), and 1,3-diaminopropane (DAP), with different DAP content. The chemical structure of the obtained poly(trimethylene 2,5-furandicarboxylate)-co-poly(propylene furanamide) (PTF-co-PPAF) copolymers was confirmed by nuclear magnetic resonance (1H NMR) and Fourier-transform infrared (FTIR) spectroscopy. Gas chromatography/mass spectrometry was used to provide more details of the polycondensation process. Thermal properties of the obtained materials were characterized by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic–mechanical thermal analysis (DMTA). The copolymers were amorphous and their glass transition temperature increased with the increase in the poly(propylene furanamide) (PPAF) content. The synthesized PTF-co-PPAF copolymers exhibited improved thermal and thermo-oxidative stability up to 300 °C. In addition, from the performed mechanical tests, it was found that along with the increase in PPAF content, Young's modulus increased, while at the same time, the value of elongation at break decreased. Graphical Abstract
Sandra Paszkiewicz, Izabela Irska, Konrad Walkowiak, and Agata Zubkiewicz
LUKASIEWICZ Research Network - Industrial Chemistry Research Institute
Poly(hexamethylene 2,5-furanate) (PHF) was obtained by melt polycondensation. The process was carried out at temperatures of 230, 235 and 240 ° C. It has been shown that the selection of the optimal parameters of the synthesis process leads to the obtaining of biomaterials of high molecular weight, and thus better mechanical and thermal properties. The relationship between the molecular weight and the mobility of polymer chains, and consequently the temperature of phase changes and mechanical properties, was determined.
Konrad Walkowiak, Izabela Irska, Agata Zubkiewicz, Zbigniew Rozwadowski, and Sandra Paszkiewicz
MDPI AG
The growing ecological awareness of society created the tendency to replace petrochemically based materials with alternative energy carriers and renewable raw materials. One of the most requested groups of polymer materials with significant technological importance is thermoplastic elastomers (TPE). They combine the properties of elastomers such as flexibility with the typical properties of thermoplastics, like easy processing. Herein, one compares the influence of rigid segments on the properties of copoly(ester-ether). Thermoplastic polyesters based on bio-1,6-hexanediol and terephthalic (T), furanic (F), and napthalate (N) diesters, i.e., PHT, PHF, and PHN, were obtained employing melt polycondensation. Additionally, to grant elastic properties of polyesters, systems containing 50 wt.% of bio-based polyTHF®1000 (pTHF) with a molecular mass of 1000 g/mol, have been prepared. The composition and chemical structure have been determined by 1H nuclear magnetic resonance (NMR) and Fourier transformed infrared spectroscopy (FTIR) analyses. The temperatures corresponding to phase transition changes were characterized by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) analyses. The crystalline structure was examined by X-ray diffraction (XRD) analysis. Additionally, the influence of pTHF–rich segment on the tensile properties, water absorption, as well as thermal and thermo-oxidative stability, has been analyzed. It was found that incorporation of soft phase allows creation of thermoplastic elastomers with tensile characteristics comparable to the commercially available ones, by means of elongation at break higher than 500%, low values of tensile modulus, without exhibiting yield point.
Pawel Lesiak, Alicja Kisielowska, Konrad Walkowiak, Aleksandra Wiktorczyk, Grzegorz Kramek, Mateusz Wypych, Lukasz Sadkowski, Jan Zielinski, Sandra Paszkiewicz, Izabela Irska,et al.
LUKASIEWICZ Research Network - Industrial Chemistry Research Institute