Polimeri na bazi obnovljivih sirovina – II. dio

A short review of biopolymers based on starch (starch derivatives, thermoplastic starch), lignin and hemicelluloses, chitin (chitosan) and products obtained by degradation of starch and other polysaccharides and sugars (poly(lactic acid), poly(hydroxyalkanoates)), as well as some of their basic properties and application area, are given in this part. The problem of environmental and economic feasibility of biopolymers based on renewable raw materials and their competitiveness with polymers based on fossil raw materials is discussed. Also pointed out are the problems that appear due to the increasing use of agricultural land for the production of raw materials for the chemical industry and energy, instead for the production of food for humans and animals. The optimistic assessments of experts considering the development perspectives of biopolymers based on renewable raw materials in the next ten years have also been pointed out. At the end of the paper, the success of a team of researchers gathered around the experts from the company Bayer is indicated. They were the first in the world to develop a catalyst by which they managed to effectively activate CO- and incorporate it into polyols, used for the synthesis of polyurethanes in semi-industrial scale. By applying this process, for the first time a pollutant will be used as a basic raw material for the synthesis of organic compounds, which will have significant consequences on the development of the chemical industry, and therefore the production of polymers.U okviru ovoga dijela rada dan je kratak prikaz biopolimera na bazi škroba (derivati škroba, termoplastièni škrob), lignina i hemiceluloze, hitina (hitozan) i na bazi proizvoda razgradnje škroba, drugih polisaharida i šećera (poli(mliječna kiselina), polihidroksialkanoati), kao i neka njihova osnovna svojstva i područje primjene. Razmatran je problem ekološke i ekonomske prihvatljivosti biopolimera na bazi obnovljivih sirovina i njihove konkurentnosti s polimerima na bazi fosilnih sirovina. Ukazano je i na probleme do kojih već dolazi zbog sve veće upotrebe poljoprivrednog zemljišta za proizvodnju sirovina za kemijsku industriju i energente, umjesto za proizvodnju hrane za ljude i životinje. Ukazano je također na optimistične procjene stručnjaka o perspektivi razvoja proizvodnje biopolimera na bazi obnovljivih sirovina. Na kraju rada je ukazano i na uspjeh tima istraživača okupljenih oko stručnjaka tvrtke Bayer, koji su prvi u svijetu razvili katalizator, pomoću kojeg su uspjeli učinkovito aktivirati CO i ugraditi ga u poliole, koje upotrebljavaju za sintezu poliuretana u poluindrustrijskim razmjerima. Ovim postupkom će prvi put jedan zagađivač biti upotrijebljen kao osnovna sirovina za sintezu organskih spojeva, što će imati nesagledive posljedice na razvoj kemijske industrije, a samim tim i proizvodnje polimera

Mechanical properties and particle size of the waterborne polyurethanes

In this study, six waterborne polyurethanes (WBPUs) were synthesized based on α,ω- dihydroxypropyl poly(dimethylsiloxane) (PDMS), isophorone diisocyanate (IPDI), 2,2- bis-(hydroxymethyl) propionic acid (DMPA) and triethylamine (TEA). WBPUs were prepared without a chain extension step and with various DMPA/PDMS molar ratios (from 0.2 to 0.7). The mechanical features, particle size and particle size distribution, as well as molecular weights of WBPUs were investigated by diverse experimental techniques. Tensile strength values were in the range from 4.03 to 6.33 MPa, and generally decrease with decreasing PDMS content in WBPUs. This occurs due to the presence of lower degree of microphase separation in WBPUs with lower PDMS content. On the other hand, the incorporation of flexible PDMS led to an increase of elongation at break values (from 0.4 to 58.6%) in WBPUs. The particle size of the prepared WBPU dispersions and molecular weight of WBPU films decrease with increasing DMPA content. Particle sizes of these WBPU dispersions are in the range from 91.4 to 232.3 nm, while the weight average molecular weights (Mw) are in the range from 11900 to 15300 g/mol [1]. Prepared WBPUs are polymer materials with good mechanical features and suitable particle sizes, which enable them to be used as coatings for different purposes

Morphology of the Polyurethane Networks Based on Polycaprolactone

Polyurethane networks (PUNs) are versatile materials that have a wide range of applications. Their structure is often segmented which means that it is built from thermodynamically incompatible flexible soft (SS) and rigid hard segments (HS) leading to the formation of microphase separation in the PUNs. With the careful design and selection of SS and HS it’s possible to control PUNs structure, morphology, solvent resistance, etc. Here, polycaprolactone (PCL) was used as SS to prepare segmented PUNs, due to its attractive features, such as low glass transition temperature (around -60 °C), biocompatibility, biodegradability, hydrophobicity, good solubility in various solvents, high permeability to many gasses, etc., in order to prepare PUNs with desired surface properties for their application as coatings [1,2]. In this study, a series of PUNs was synthesized by a two-step polymerization process, according to the procedure described elsewhere [1,3]. The synthesized PUNs are based on Boltorn® hydroxy-functional aliphatic hyperbranched polyester of the second pseudo generation (BH-20, Mn = 1340 g mol-1), isophorone diisocyanate (IPDI) and polycaprolactone diol (PCL, Mn = 2000 g mol-1). Five samples with diferent SS content (from 10 to 50 wt.% SS content) and constant –NCO/−OH molar ratio of 1.05 were synthesized. Stannous octoate (Sn(Oct)2 ) was used as a catalyst, while a mixture of N,N-dimethylacetamide (DMAc) and tetrahydrofuran (THF) was used as a solvents during the synthesis of PUNs. PUN samples were labeled as PUN-XX, where XX represents the SS content (from 10 to 50). Surface morphology and the surface roughness of the PUNs were investigated by atomic force microscopy (AFM). AFM examination of PUNs was performed by applying NTEGRA Prima atomic force microscope (NT-MDT, Moscow, Russia). Measurements were done using NT-MDT NSGO1 silicon cantilevers (N-type, antimony doped with Au reflective coating). The nominal force constant of the cantilevers was 5.1 N m-1, whereas the cantilever driving frequency was around 150 kHz. Intermittent-contact AFM mode was applied and data related with topography and phase were collected. AFM images were created and analyzed with Image Analysis 2.2.0 (NT-MDT) and Gwyddion 2.61 (Free and Open Source software, Czech Metrology Institute) software. The scan area of the PUNs surface was 20 × 20 μm2. AFM analysis was carried out to explore the surface topography, homogeneity and the impact of the SS content on microstructural features of the synthesized PUNs, such as nanometer scale structures and roughness. The recorded 3D height and 2D phase pictures (scan size 20 × 20 μm2) and obtained roughness values are presented in Figure 1 and Table 1, respectively. According to the captured 3D height pictures it can be seen that surface topography of PUNs strongly depends on the SS content. That is reflected in the fact that samples with smaller SS content have more flat and smoother relief structures, without any larger domains, opposite to the samples with the higher SS content. Furthermore, according to the presented 2D phase pictures it can be observed that prepared PUNs have heterogeneous surface morphology, due to the existence of more pronounced and more noticeable interface borders between phases. This behavior is more prevalent in PUN samples with higher SS content [3]. The examined roughness of the PUNs shows that samples with SS content of 30 and 40 wt.% (PUN-30 and PUN-40 samples) have the highest roughness values (Rq and Ra, Table 1). The reason for this may lie in the fact that these samples have optimal ratio between HS and SS, allowing easier organization of SS [4]. A series of PUNs based on BH-20, IPDI and PCL was successfully synthesized. AFM analysis showed that the content of SS has a significant impact on the surface properties of these PUNs. Moreover, PUNs have two phase morphology that originates from the presence of HS and SS, and it was more pronounced in the samples with higher SS content [5].

Contribution to sustainable development by application and recycling of packaging made from polymer materials

U poslednjih dvadesetak godina došlo je do naglog porasta primene polimernih materijala za izradu ambalaže praktično svih vrsta proizvoda, a naročito prehrambenih, kozmetičkih i farmaceutskih. I pored toga, u svetu, a i kod nas, dosta često se čuju ideje da polimerni materijali zadovoljavaju sve tehničke i ekonomske uslove, ali zbog toga što ne mogu da se uklope u kružni tok materije u prirodi oni zagađuju čovekovu sredinu i samim tim ne zadovoljavaju ekološke uslove, pa ih ne treba koristiti za izradu ambalaže, a naročito ne za pakovanje životnih namirnica. U okviru ovoga rada ukazano je na neke rezultate ostvarene u svetu na polju ekologije i ekonomije primenom i recikliranjem ambalaže od polimernih materijala, kao i njen doprinos održivom razvoju. Na osnovu do sada ostvarenih rezultata očekuje se da će primena ambalaže od polimernih materijala u nerazvijenim zemljama, i to naročito za pakovanje prehrambenih proizvoda, značajno doprineti da se smanje razlike u stepenu razvijenosti zemalja sveta.In the last twenty years a rapid increase occurred in the application of polymer materials for packaging of practically all types of products, especially food, cosmetics and pharmaceuticals. Nevertheless, in the world and in Serbia as well, one can quite often hear the ideas that polymer materials satisfy all the technical and economic conditions, but because they cannot fit into the circular flow of matter in nature, they pollute the environment and therefore do not meet ecological requirements, so they should not be used for packaging, and especially not for packaging of foodstuffs. In this paper it is pointed out on some results obtained in the world in the field of ecology and economy by application and recycling of packaging made from polymer materials, as well as its contribution to the sustainable development. Based on the recent results, it is expected that application of packaging made from polymer materials in developing countries, particularly in food packaging, will significantly contribute to the reduction of differences in the development degree of countries

Preparation and swelling properties of polyurethane/TiO2 nanocomposites

Polyurethane/TiO2 nanocomposites (NCs) were fabricated from environmentally friendly polyurethane (PU) network, based on polycaprolactone (PCL) and Boltorn® aliphatic hyperbranched polyester of the second pseudo generation (BH-20) as crosslinking agent, and unmodified and surface modified TiO2 nanoparticles (NPs). The surface modification of TiO2 NPs was done with lauryl gallate. The chemical structure of the prepared PU/TiO2 NCs was studied by Fourier transform infrared spectroscopy (FTIR), while their amorphous nature was confirmed by Xray diffraction (XRD). The influence of type and content of the applied TiO2 NPs on swelling properties in toluene and tetrahydrofuran (THF) and on water absorption of the prepared PU/TiO2 NCs were investigated. The obtained results revealed that swelling behavior depends on the used solvent, while percentage of absorbed water decreases with increasing content of TiO2 NPs and it is generally lower in NCs prepared with modified TiO2 NPs

Synthesis and characteriaztion of polyurethanes cross-linked with aliphatic hyperbranched polyester

Two series of cross-linked polyurethanes (PUs) based on hydroxyethoxy propyl terminated poly(dimethylsiloxane) (EO-PDMS) or hydroxyl propyl terminated poly(dimethylsiloxane) (HP-PDMS) macrodiols, Boltorn® aliphatic hyperbanched polyester of the second pseudo generation (BH-20) and 4,4’-methylenediphenyl diisocyanate (MDI) were synthesized using two-step polymerization in solution. The influence of the type and content of soft PDMS segment on swelling behavior and thermal properties of PUs was investigated. The obtained results revealed that cross-linking density decreases, while thermal stability increases with increasing soft segment content. Furthermore, PUs based on EO-PDMS have higher cross-linking density and better thermal stability than samples synthesized using HPPDMS

The effect of silver nanofillers on the thermal properties of polystyrene

Nanocomposites (NCs) comprised of metal nanoparticles (NPs) embedded in polymer matrices usually exhibit a simple combination of the physical properties of the polymer, along with the specific optical or electrical characteristics associated with the NPs. However, novel behavior can arise thanks to synergistic effects between the NPs and polymer matrix. The present work represents the continuation of our study on the interaction between silver nanoparticles (Ag NPs) and polystyrene (PS) matrix that govern the properties of polymer. Namely, in order to achieve homogeneous distribution of Ag NPs in the PS matrix, the in situ bulk radical polymerization of styrene was performed in the presence of monodisperse surface modified Ag NPs. The influence of the presence of Ag NPs and their concentration on the glass transition temperature and thermal stability of PS matrix was investigated in details using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) performed in argon and air atmosphere. The results indicated that thermal and thermo-oxidative stability of PS were improved upon incorporation of Ag NPs. The Ag/PS NCs have lower glass transition temperatures than neat PS because loosely packed oleylamine molecules at the interface caused the increase of free volume and chain segments mobility near the surface of Ag NPs

Održivi razvoj i polimerni materijali

In the last twenty years, a rapid growth in the application of polymer materials occurred in practically all fields of human activities, especially for packaging. Never the less, in the world and our country, quite often one can hear the ideas that polymer materials satisfy all the technical and economic requirements, but because they cannot fit into the circular flow of matter in nature, they pollute the environment and therefore do not satisfy the environmental criteria, so they should not be used for example, for packaging and in particular not for food packaging. In the first part of this article the reasons which led to the pollution of our planet earth are pointed out and also what is done in order to preserve the environment and to accept and introduce into the life ideas of sustainable development. In the second part it is shown, on selected examples, in which amount application of polymer materials based on fossil or renewable raw materials contributes to sustainable development. It is also shown that by recycling of polymer waste into new materials and raw materials or its combustion, significant savings in raw materials and energy can be achieved, which further contributes to sustainable development. In addition, polymer materials have significantly contributed to the rapid development of many technologies, such as: technology of transport vehicles production, construction, electronics and electrotechnics, graphic techniques, textiles, sports equipment and in a specific manner contributed to the reduced consumption of raw materials, energy and CO2 emission. Based on the presented data it can be concluded that the polymer materials are environmentally friendly, which is one of the reason for planned annual polymer production growth of 4 to 8% in the next twenty years.U poslednjih dvadesetak godina došlo je do naglog porasta primene polimernih materijala u praktično svim oblastima ljudskih delatnosti, a naročito za izradu ambalaže. I pored toga, u svetu, a i kod nas, dosta često se čuju ideje da polimerni materijali zadovoljavaju sve tehničke i ekonomske uslove, ali zbog toga što ne mogu da se uklope u kružni tok materije u prirodi oni zagađuju životnu sredinu i samim tim ne zadovoljavaju ekološke kriterijume, pa ih ne treba koristiti npr. za izradu ambalaže, a naročito ne ambalaže za pakovanje životnih namirnica. U prvom delu ovoga rada ukazano je na razloge koji su doveli do zagađenja naše planete zemlje i šta se čini u cilju očuvanja životne sredine i prihvatanju i uvođenju u život ideje o održivom razvoju. U drugom delu rada je na izabranim primerima pokazano koliki doprinos održivom razvoju se ostvaruje primenom polimernih materijala na bazi fosilnih ili obnovljivih sirovina. Pokazano je takođe da se recikliranjem polimernog otpada u nove materijale i sirovine ili njegovim sagorevanjem mogu ostvariti značajne uštede u sirovinama i energiji i tako dodatno doprineti održivom razvoju. Pored toga, polimerni materijali su značajno uticali na ubrzan razvoj velikog broja tehnologija, kao što su npr: tehnologija proizvodnje transportnih sredstava, građevinarstva, elektronike i elektrotehnike, grafičke tehnike, tekstila, sportske opreme i tako na jedan specifičan način doprineli smanjenoj potrošnji sirovina, energije i emisije CO2. Na osnovu prikazanih podataka može se zaključiti da su polimerni materijali ekološki materijali i da je to jedan od razloga što je za polimerne materijale za sledećih dvadeset godina predviđen godišnji porast proizvodnje od 4 do 8 %

Waterborne polyurethanes based on poly(dimethylsiloxane)

A series of novel waterborne polyurethanes (WBPUs) was synthesized using α,ω- dihydroxypropyl poly(dimethylsiloxane) (PDMS), isophorone diisocyanate (IPDI), 2,2-bis- (hydroxymethyl) propionic acid (DMPA) and triethylamine (TEA). Different DMPA/PDMS and constant –NCO/–OH molar ratio have been applied for the synthesis of six different WBPUs, without the usage of chain extension step. The structure-properties relationship was examined with diverse experimental analyses. ATR-FTIR, 1H and 13C NMR analyses confirmed the incorporation of PDMS parts inside polyurethane backbone and the successful preparation of WBPUs. XRD analysis showed that all WBPUs are amorphous, without any kind of threedimensional order. According to the conducted TG measurements, the incorporation of PDMS increases thermal stability of WBPUs. DMA results confirmed the existence of microphase separation, which was more pronounced in WBPUs with higher PDMS content. Contact angle measurements with water confirmed good surface hydrophobicity of these WBPUs, which originates from the high percentages of Si atoms present on the surface of WBPU films. Good hydrophobicity originates from PDMS which has known to possess low surface energy and have a high tendency to migrate on the surface of the WBPUs. The synthesis of these WBPUs represents a more efficient and eco-friendly way for preparation of polyurethanes and they are good candidates for application as coatings

Održivi razvoj i polimerni materijali

In the last twenty years, a rapid growth in the application of polymer materials occurred in practically all fields of human activities, especially for packaging. Never the less, in the world and our country, quite often one can hear the ideas that polymer materials satisfy all the technical and economic requirements, but because they cannot fit into the circular flow of matter in nature, they pollute the environment and therefore do not satisfy the environmental criteria, so they should not be used for example, for packaging and in particular not for food packaging. In the first part of this article the reasons which led to the pollution of our planet earth are pointed out and also what is done in order to preserve the environment and to accept and introduce into the life ideas of sustainable development. In the second part it is shown, on selected examples, in which amount application of polymer materials based on fossil or renewable raw materials contributes to sustainable development. It is also shown that by recycling of polymer waste into new materials and raw materials or its combustion, significant savings in raw materials and energy can be achieved, which further contributes to sustainable development. In addition, polymer materials have significantly contributed to the rapid development of many technologies, such as: technology of transport vehicles production, construction, electronics and electrotechnics, graphic techniques, textiles, sports equipment and in a specific manner contributed to the reduced consumption of raw materials, energy and CO2 emission. Based on the presented data it can be concluded that the polymer materials are environmentally friendly, which is one of the reason for planned annual polymer production growth of 4 to 8% in the next twenty years.U poslednjih dvadesetak godina došlo je do naglog porasta primene polimernih materijala u praktično svim oblastima ljudskih delatnosti, a naročito za izradu ambalaže. I pored toga, u svetu, a i kod nas, dosta često se čuju ideje da polimerni materijali zadovoljavaju sve tehničke i ekonomske uslove, ali zbog toga što ne mogu da se uklope u kružni tok materije u prirodi oni zagađuju životnu sredinu i samim tim ne zadovoljavaju ekološke kriterijume, pa ih ne treba koristiti npr. za izradu ambalaže, a naročito ne ambalaže za pakovanje životnih namirnica. U prvom delu ovoga rada ukazano je na razloge koji su doveli do zagađenja naše planete zemlje i šta se čini u cilju očuvanja životne sredine i prihvatanju i uvođenju u život ideje o održivom razvoju. U drugom delu rada je na izabranim primerima pokazano koliki doprinos održivom razvoju se ostvaruje primenom polimernih materijala na bazi fosilnih ili obnovljivih sirovina. Pokazano je takođe da se recikliranjem polimernog otpada u nove materijale i sirovine ili njegovim sagorevanjem mogu ostvariti značajne uštede u sirovinama i energiji i tako dodatno doprineti održivom razvoju. Pored toga, polimerni materijali su značajno uticali na ubrzan razvoj velikog broja tehnologija, kao što su npr: tehnologija proizvodnje transportnih sredstava, građevinarstva, elektronike i elektrotehnike, grafičke tehnike, tekstila, sportske opreme i tako na jedan specifičan način doprineli smanjenoj potrošnji sirovina, energije i emisije CO2. Na osnovu prikazanih podataka može se zaključiti da su polimerni materijali ekološki materijali i da je to jedan od razloga što je za polimerne materijale za sledećih dvadeset godina predviđen godišnji porast proizvodnje od 4 do 8 %