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1

Effect of crystallinity and surface silanol groups on rheological properties of different sepiolites

Çınar Mustafa, Gülgönül Ilhan, Ozdemir Orhan, Çelik Mehmet S.

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 5

art. no. 153947

EN

In this study, differences in the rheological properties of three different types of brown sepiolites (K1, K2, and K3) along with one beige (B) sepiolite with different physicochemical properties were explained based on their crystallinity and level of surface silanol groups. Towards this aim, SEM images, XRD and chemical analyses, cation exchange capacity (CEC), and water absorption tests were conducted along with surface area measurements and time-dependent pH profiles. The pH profiles at 3% by wt. revealed that each sepiolite sample attained the equilibrium at different times. These differences showed a parallel behavior with the degree of crystallinity. While sepiolite with better crystallinity (K1) was rather slow in reaching the equilibrium pH, the sepiolites with poor crystallinity (B and K3) reached their equilibrium pH more quickly. The rheological studies conducted with different sepiolites at 3% solids concentration exhibited time-dependent flow of the Bingham plastic model and thixotropic. Differences observed in the rheological behavior of sepiolites were found to correlate with the fiber size, CEC, surface area, and water absorption. The results further indicated that sepiolites with low crystallinity or high level of surface silanol groups (K3 and B sepiolites) show the best rheological properties.

2

Structural and Morphological Evaluations of Natural Hydroxyapatite from Calcined Animal Bones for Biomedical Applications

Ojo Olusola Emmanuel, Sekunowo Olatunde Israel, Ilomuanya Margaret Okonawan, Gbenebor Oluwashina Philips, Adeosun Samson Oluropo

Journal of Casting & Materials Engineering

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2022

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Vol. 6, no. 1

14--21

EN

Several biomedical materials have been employed as drug delivery systems, but natural Hydroxyapatite (HAP) has been proven to be exceptionally better than other materials owing to its excellent bioactivity and biocompatibility properties. In this study, natural HAP was obtained from bovine and caprine bones and comparatively analysed for biomedical applications. The bones were hydrothermally treated, calcined in the temperature range of 700–1100°C, held for 2 hours in an electric furnace to remove the organic contents; milled, sifted with 150 μm mesh sieve and then characterized. It was revealed by Energy Dispersive X-Ray Spectroscopy (EDS) that the bovine and caprine bone samples calcined at 1000°C had calcium/phosphorus ratio (Ca/P) of 1.66 closest to the standard of 1.67. The bovine HAP showed the best crystallinity (86.23%) at 1000°C while caprine HAP had its highest (87.25%) at 1100°C. Fourier Transform Infrared Spectroscopy (FTIR) results revealed that the calcination temperature must be greater than 700°C to isolate high quality HAP. The Scanning Electron Microscopy (SEM) showed that the samples calcined at 800°C had the largest average particle size (85.34 μm) while porosity increases with calcination temperature in both samples. The HAP obtained at a calcination temperature of 1000°C proved to have the best quality for biomedical applications.

3

Investigating the Effect of Photo-Oxidative Degradation on the Ageing Resistance of the Car Mudflaps Manufactured with Post-Production High-Density Polyethylene Wastes

Czarnecka-Komorowska Dorota, Swain Chandra, Kopeć Bogdan, Borowski Jacek, Garbacz Tomasz

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 4

38--47

EN

The paper presents the results of the ageing resistance of automotive mudflaps made of recycled polyethylene blends. The mudflaps were manufactured by a plastic sheet extrusion-calendaring process in Novotech Kostrzyn nad Odrą company. The changes of the mechanical properties in the tensile test and impact toughness test as well as in Shore hardness due to the accelerated aging process were characterized, taking into account the aging sensitivity coefficient (KI), and changes in the structure within the wavenumber range 4000-400 cm-1, taking into account the CI coefficient. The results showed a higher melting point and crystallinity for the recycled HDPE blends during photo-oxidative degradation. Moreover, the results presented decreased tensile strength and ductility, due to macromolecular chain scission caused by oxidation. It was found that the blends of HDPE based on recycled materials are more sensitive to the aging process than virgin HDPE. Finally, it can be concluded that the sensitivity to ageing blends increases with the increase of recycled HDPE content in the HDPE matrix.

4

Wear resistance improvement of linear block-polyurethanes under conditions of liquid friction

Panda Anton, Anisimov Volodymyr M., Anisimov Volodymyr V., Dyadyura Konstantin

Management Systems in Production Engineering

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2021

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nr 4 (29)

287--293

EN

A significant disadvantage of parts made of linear block polyurethanes under conditions of friction contact in the presence of an aqueous medium is the intensification of hydrolysis processes and decrease in volume strength. It was proposed to slow down the hydrolysis of polyurethanes in three ways: by directed changes in chemical structure, by electromagnetic radiation of different intensities and by creation of composite materials, based on the principle of additional intermolecular crosslinking at the manufacturing and hot processing stages. The conditions for the formation of a smooth wear-resistant surface that protects the material from rapid destruction are revealed.

5

A comparison of the structure of lamellar stacks in a semicrystalline polymer during melting and crystallization by means of the Intensity Superposition Method

Rabiej Stanisław, Rabiej Małgorzata

Polimery

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2020

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T. 65, nr 9

632--638

EN

This work presents the results of Small Angle X-ray Scattering (SAXS) investigations of the structure of lamellar stacks in ethylene-1-octene copolymer during heating and cooling. The SAXS curves were analysed using the Intensity Superposition Method (ISM). By means of this method, not only the average values of the parameters of lamellar stacks but also the stacks crystallinity distribution function were determined. Based on this function, the structure of lamellar stacks during crystallization and melting of the copolymer was compared and observed differences were indicated.

PL

Przedstawiono wyniki badań struktury stosów lamelarnych w kopolimerach etylen-1-okten, wykonane metodą małokątowego rozpraszania promieni rentgenowskich (SAXS) w trakcie ogrzewania i chłodzenia. Krzywe SAXS analizowano przy użyciu Metody Superpozycji Intensywności (ISM). Metoda ta pozwoliła wyznaczyć nie tylko średnie wartości parametrów stosów, ale także funkcję rozkładu stopnia krystaliczności stosów. Na podstawie analizy tej funkcji wykazano istotne różnice w strukturze stosów lamelarnych w procesach krystalizacji i topnienia.

6

Effect of sago starch and plasticizer content on the properties of thermoplastic films: mechanical testing and cyclic soaking-drying

Halimatul M. J., Sapuan S. M., Jawaid M., Ishak M. R., Ilyas R. A.

Polimery

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2019

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T. 64, nr 6

422--431

EN

Studies on the effect of sago starch and plasticizer concentrations on the tensile and tearing properties of the produced starch films were carried out using universal testing machine. The results showed that both sago starch and plasticizer contents significantly affected the mechanical properties of starch films. With increasing the starch concentration, an increase in tensile strength was observed. This was accompanied by radically reduced tensile strain and increased tearing strength. On the contrary, when increasing the plasticizer concentration, a reduction in tensile and tearing strength was observed, as well as an increment in tensile strain. The results of repeated soaking and drying tests made on sago starch films showed that the films with high plasticizer and low starch content exhibited lower mass loss compared to those containing lower plasticizer and higher starch concentration. Increasing the number of soaking and drying cycles reduced starch dissolution and it was probably related to retrogradation process inside the film. In a nutshell, the study provided preliminary information to assess the possible application fields of sago starch films.

PL

Z zastosowaniem uniwersalnej maszyny testującej zbadano zależność wytrzymałości na rozciąganie i rozdarcie wytworzonych błon skrobiowych od zawartości w nich skrobi sago i plastyfikatora. Stwierdzono, że udział zarówno skrobi, jak i plastyfikatora (mieszanina sorbitolu i glicerolu 1 : 1) wpływają wyraźnie na właściwości mechaniczne otrzymanych błon. Zwiększenie zawartości skrobi powodowało wzrost wytrzymałości na rozciąganie połączone z drastycznym zmniejszeniem wartości naprężenia. Ponadto zwiększyła się wytrzymałość na rozerwanie. Większa zawartość plastyfikatora w błonie skrobiowej, w przeciwieństwie do udziału skrobi sago, prowadziła do zmniejszenia wytrzymałości na rozciąganie przy zwiększeniu wartości naprężenia, a także do zmniejszenia wytrzymałości na rozerwanie. Wyniki testu cyklicznego moczenia i suszenia błon skrobiowych sago wykazały, że błony z dużą zawartością plastyfikatora i małym udziałem skrobi charakteryzowały się małym ubytkiem masy, w przeciwieństwie do błon z dużą zawartością skrobi i małym udziałem plastyfikatora. Zwiększanie liczby cykli moczenia i suszenia wpływało na ograniczenie procesu rozpuszczania skrobi wwodzie, co można tłumaczyć przebiegającą retrogradacją cząsteczek skrobiowych sago. Przeprowadzone badania mogą być przydatne do określenia obszarów potencjalnych zastosowań błon wytworzonych ze skrobi sago.

7

Wpływ struktury krystalicznej powłoki diamentowej na skrawność płytek z węglików spiekanych przy frezowaniu

Jemielniak Krzysztof

Mechanik

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2019

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R. 92, nr 12

806

PL

Płytkami z węglików spiekanych powlekanych mikrokrystalicznym diamentem można efektywnie obrabiać materiały nieżelazne, takie jak stopy aluminium czy tworzywa sztuczne wzmacniane włóknem węglowym. Parametry stosowane w trakcie powlekania istotnie wpływają na strukturę i właściwości powłoki.

8

Effect of Supercritical Carbon Dioxide on Dyeability and Physical Properties of Ultra-High-Molecular-Weight Polyethylene Fiber

Ma Jaehyuk, Elmaaty Tarek Abou, Okubayashi Satoko

Autex Research Journal

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2019

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Vol. 19, no. 3

228--235

EN

Supercritical carbon dioxide dyeing, a new type of anhydrous dyeing method, has a lot of advantages, mainly conservation of energy, prevention of pollution, reusability of dye, and many more. This study presents a viable method for the dyeing of an ultra-high-molecular-weight polyethylene (UHMWPE) fabric by using supercritical carbon dioxide (scCO2) as a medium. Five hydrozono propanenitrile dyes that are functional colorants having antibacterial activity were applied for the dyeing of the UHMWPE fabric in scCO2 at a pressure of 20 MPa and at temperature of 120°C. The dyeability of UHMWPE fabric under scCO2 was evaluated by color measurement, whereby the color strength K/S was calculated. As the treating time and concentration of dye increased, the dyeability of the UHMWPE fabric displayed the tendency to continually improve. As decaline was added into scCO2 as the cosolvent, we obtained higher K/S. Furthermore, color fastness to rubbing and sublimation of the dyed UHMWPE fabric were determined according to Japanese Industrial Standards (JIS) L 0849 2 and JIS L 0854, and the trend showed that the increase in fastness corresponded to the increase in duration of the treatment. The influence of scCO2 dyeing on the mechanical properties of UHMWPE was also examined. Consequently, it was found that dyeing in scCO2 containing decaline reduced the crystallinity of the UHMWPE fabric and the breaking strength decreased. The antimicrobial property of UHMWPE dyed with N′-(2-chloro-4-methylphenyl)-2-oxo-2-(p-tolyl)acetohydrazonoyl cyanide was tested against three different microorganisms, and the results have been reported.

9

High transparency and conductivity of heavily In-doped ZnO thin films deposited by dip-coating method

Benzitouni S., Zaabat M., Mahdjoub A., Benaboud A., Boudine B.

Materials Science Poland

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2018

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Vol. 36, No. 3

427--434

EN

Heavily In doped zinc oxide (IZO) thin films were deposited on glass substrates by dip-coating method with different concentrations of indium. The effect of heavy In doping on the structural, morphological, optical and electrical properties of ZnO was discussed on the basis of XRD, AFM, UV-Vis spectra and Hall effect measurements. The diffraction patterns of all deposited films were indexed to the ZnO wurtzite structure. However, high In doping damaged the films crystallinity. The highest optical transmittance observed in the visible region (>93 %) exceeded that of ITO: the absolute rival of the most commercial TCOs. The grain size significantly decreased from 140 nm for undoped ZnO to 17.1 nm for IZO with the greatest In ratio. The roughness decreased with increasing In atomic ratio, indicating an improvement in the surface quality. Among all synthesized films, the sample obtained with 11 at.% indium showed the best TCO properties: the highest transmittance (93.5 %) and the lowest resistivity (0.41 Wcm) with a carrier concentration of 2.4 × 1017 cm-3. These results could be a promising solution for possible photonic and optoelectronic applications.

10

LMPP Effects on Morphology, Crystallization, Thermal and Mechanical Properties of iPP/LMPP Blend Fibres

Hussain M., Zhu F., Yu B., Han J., Memon H., Yasin S.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 2 (128)

26--31

EN

The thermal properties and morphological characterisation of isotactic polypropylene (iPP) homopolymer and its blends with low molecular low modulus polypropylene (LMPP) were studied. Firstly blends were prepared with variant LMPP contents, and their properties were characterised using SEM, DSC, XRD, and DMA. Later the mechanical properties of iPP/LMPP blend fibres were investigated. SEM results showed that the iPP/LMPP blends produced smoother surfaces when the LMPP content was increased, as well as the miscibility. All the Tg values with different LMPP percentages were in-between pure iPP and LMPP. The XRD results indicated the LMPP percentage decreased along with the degree of crystallinity of the iPP/LMPP blends (5% to 15%), which increased and then decreased as compared to pure iPP. The elongation at break increased when the LMPP content increased, with the maximum elongation at break of the LMPP 25% blend reaching 12.95%, which showed great stretch-ability, whereas the elastic modulus of iPP/LMPP blends decreased.

PL

W pracy badano właściwości termiczne i morfologię homopolimeru izotaktycznego polipropylenu (iPP) i jego mieszanek z polipropylenem o małej masie cząsteczkowej (LMPP). Zastosowano następujące proporcje mieszania iPP/LMPP (wt/wt): 95/5, 90/10, 85/15, 80/20 i 75/25, zdefiniowano je odpowiedni: 5%, 10%, 15 %, 20% i 25%. Właściwości włokien mieszanych iPP/LMPP porównano do właściwości czystego PP i LMPP. Włókna mieszane zbadano za pomocą SEM, DSC, XRD i DMA. Następnie zbadano mechaniczne właściwości włókien iPP/LMPP. Wyniki SEM wykazały, że wraz ze zwiększeniem zawartości LMPP powierzchnia włókien charakteryzowała się większą gładkością. Wszystkie wartości Tg włókien mieszanych były pośrednie pomiędzy czystym iPP i LMPP. Stwierdzono, że wydłużenie przy zerwaniu zwiększyło się wraz ze wzrostem zawartości LMPP, przy maksymalnym wydłużeniu przy zerwaniu 12,95%, dla włókien z zawartością 25% LMPP, co wskazywało na dużą rozciągliwość, podczas gdy moduł sprężystości wzdłużnej włókien iPP / LMPP zmniejszył się.

11

Films LDPE/LLDPE made from post – consumer plastics: processing, structure, mechanical properties

Czarnecka-Komorowska Dorota, Wiszumirska Karolina, Garbacz Tomasz

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 3

134--142

EN

The paper presents the results of the investigation into the themo-mechanical, rheological and structural properties of films made from recycled polyethylenes in the “foil-to-foil” system, the comparative material were films made from primary raw materials. The films were prepared by melt mixing technique in a single screw extruder. Primary polyethylenes, recyclates and their blends were used. The aim of the research was to determine the quality of the materials derived from the closed process of the recycling of polyethylene film in comparison to virgin plastics. The mechanical properties of the films were measured by tensile test and puncture test. The morphology was studied using polarized light microscopy (POM) and FT-IR measurements. DSC and shrinkage were used to determine thermal behavior and the degree of crystallinity. The results showed that the obtained recycled blends rLDPE/rLLDPE are high-quality material with good processing properties susceptible to the production of thin films. Studies on the mechanical properties of the recycled blends showed an increase in tensile strength and elongation. An increase in the melting temperature and heat of fusion, as determined from DSC, was observed with an increase in the recycled blends. Puncture results demonstrated that the post-consumer recycled film was more strength than the film made from virgin plastics. Thus, these materials may serve as valuable recycled plastics useful for packaging applications.

12

Ocena wpływu stopnia krystaliczności polietylenu dużej gęstości na twardość rur z PE-HD

Palutkiewicz P., Baranowski W.

Przetwórstwo Tworzyw

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2016

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T. 22, Nr 4 (172)

332--339

PL

W artykule przeanalizowano wpływ stopnia krystaliczności na twardość rur z polietylenu dużej gęstości PE-HD. Przedmiotem badań byly rury z PE-HD do przesyłu gazu i wody. Średnica zewnętrzna wynosiła dn = 311 mm a grubość ścianki en = 28 mm czyli SDR = 11. Określono stopień krystaliczności metodą DSC w ściance rury w od zewnętrznej średnicy rury do wewnętrznej średnicy czyli w całym przekroju ścianki. Zbadano jaki wpływ na stopień krystaliczności PE-HD ma sposób chłodzenia chłodzona wodą na linii wytaczarskiej w urządzeniu chłodzącym. Dokonano oceny twardości w zależności od stopnia krystaliczności. Przedstawiono mikrostrukturę przekroju ścianki rury.

EN

The influence of degree of crystallinity on hardness of pipes made from high-density polyethylene (HDPE) was analyzed in this paper. The pipes for natural gas and water with outside diameter dn = 311 mm and wall thickness en = 28 mm (SDR = 11) was examinated. Crystallinity degree was exanimated using the DSC method, in the entire pipe wall thickness - from outside to inside wall. The influence of the cooling way on HDPE crystallinity degree was also investigated. The effect of cooling methods (water and air) on the degree of crystallinity was presented. It was shown, that hardness depending on the degree of crystallinity.

13

Badania właściwości mikrostrukturalnych oraz analiza struktury nadcząsteczkowej przędzy filtracyjnej na bazie syntetycznych polimerów włóknotwórczych

Margol M., Kwiatkowski D., Wacowska A.

Przetwórstwo Tworzyw

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2016

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T. 22, Nr 4 (172)

276--284

PL

W artykule dokonano analizy mikrostruktury oraz wyznaczono procentową zawartość struktury krystalicznej (Sk) dla przędzy wykonanej z mieszaniny PP/PE mającej zastosowanie do produkcji tkanin filtracyjnych. Badania przeprowadzono przy użyciu elektronowej mikroskopii scanningowej oraz dyfraktometrii rentgenowskiej XRD. Opisano technologię wytwarzania materiału badawczego - przędzenia ze stopionej masy polimeru.

EN

This article analyzes the microstructure and determination of the percentage of crystalline structure (Sk) for a yarn made of a mixture of PP/PE applicable to the production of filter fabrics. Studies were conducted using electron microscopy and X-ray diffractometry scanningowej XRD. Described manufacturing technology research material - spinning the molten polymer.

14

Comparison of Selected Chemical Properties of Fibres from Different Breeds of Dogs and German Blackface Sheep

Ragaišienė A., Rusinavičiūtė J., Milašiene D., Ivanauskas R.

Fibres & Textiles in Eastern Europe

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2016

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Vol. 24, no. 5 (119)

21--28

EN

Combed or picked out dog hair fibre, as one of the protein fibres, could be used in yarn manufacturing. Dog hair fibres have a specific scale structure, shape and distribution on the surface. Results obtained indicated that same dog hair fibre fragmented and interrupted the continuous whole and continuous kemp medulla inside. Thus it is necessary to find differences between sheep wool and dog hair fibres as well as between different dog breeds in other areas. In this research, the crystal and chemical structures, macro-chain confirmation and surface morphology of sheep wool and dog hair fibres from different breeds were investigated through identifying variations between thus protein fibres. FTIR analysis showed that the absorbing peaks of sheep’s wool around 2920 cm–1 and 2850 cm–1 are more intense and sharper than those in the IR spectrum of dog hair fibre. Other peaks of the dog hair spectra are more intensive and have a bigger areal. Values of the crystallinity degree and indexes are different not only between sheep wool and dog hair fibres, but also among hairs of the different dog breeds too. The percentage amounts of carbon, hydrogen and nitrogen in sheep wool and dog hair fibres are of the same order of magnitude. However, the content of elements in the cortex of sheep wool and dog hair fibres varies, especially that of sulphur and oxygen, which varies by about two times among the different protein fibres.

PL

Do produkcji przędz włókien proteinowych można stosować włókna z wyczesanych sierści psów. Uzyskane wyniki wskazują, że włókna z sierści niektórych psów mogą przedstawiać interesujące właściwości dla produkcji odzieży. Dlatego postanowiono przeprowadzić porównanie strukturalne i morfologiczne włókien z wełny owczej i różnych ras psów dla identyfikacji różnic. Badania FTIR wykazały, że piki absorpcji promieniowania w zakresie 2920 cm-1 i 2850 cm-1 są bardziej intensywne, mają ostrzejszy przebieg dla wełny owczej podczas gdy dla innych częstotliwości piki mają charakter zróżnicowany. Wartości stopnia krystaliczności są różne nie tylko dla wełny owczej i psiej ale również są zróżnicowane pomiędzy wełną z różnych ras psich. Procentowe zawartości węgla, wodoru i azotu w poszczególnych rodzajach włókien są podobne, podczas gdy różnice zawartości siarki i tlenu są wyraźne.

15

The influence of chitin structure on its enzymatic deacetylation

Jaworska M., Roberts G.A.F.

Chemical and Process Engineering

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2016

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Vol. 37, nr 2

261--267

EN

The possibility of producing chitosan by enzymatic deacetylation of chitin has been the subject of numerous investigations over the last twenty years, but to date no satisfactory method has been developed. In this paper the influence of chitin chain conformation and chitin particle crystallinity on the enzymatic deacetylation of chitin is investigated to determine the relative importance of these two factors on the process. It is shown that the high crystallinity of chitin is the main obstacle to converting chitin to chitosan by enzymatic deacetylation.

16

Effect of fabrication technique on the crystalline phase and electrical properties of PVDF films

Mahato P. K., Seal A., Garain S., Sen S.

Materials Science Poland

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2015

|

Vol. 33, No. 1

157--162

EN

The effect of different fabrication techniques on the formation of electroactive β-phase polyvinylidene fluoride (PVDF) has been investigated. Films with varying concentration of PVDF and solvent – dimethyl formamide (DMF) were synthesized by tape casting and solvent casting techniques. The piezoelectric β-phase as well as non polar α-phase were observed for both the tape cast and solvent cast films from X-ray diffraction (XRD) micrographs and Fourier transform infra-red spectroscopy (FT-IR) spectra. A maximum percentage (80 %) of β-phase was obtained from FT-IR analysis for a solvent cast PVDF film. The surface morphology of the PVDF films was analyzed by FESEM imaging. The dielectric properties as a function of temperature and frequency and the ferroelectric hysteresis loop as a function of voltage were measured. An enhancement in the value of the dielectric constant and polarization was obtained in solvent cast films.

17

Modeling of the lamellar structure of ethylene-1-octene copolymers

Rabiej S., Rabiej M.

Polimery

|

2014

|

T. 59, nr 7-8

549--556

EN

The parameters of the lamellar structure of melt crystallized ethylene-1-octene copolymers were determined with the usage of model calculations. Two models were employed: classical model of Hosemann and a variable local structure model. In the second model it was assumed that the crystallinity of stacks varies from stack to stack according to some distribution function P(j). Theoretical SAXS curves related to the assumed models were best fitted to the experimental curves and the parameters of stacks were determined. It was found that the second model gave much better fits then the model of Hosemann. Generally, the distribution function P(j) is asymmetric and positively skewed but its shape changes for the stacks crystallized at various temperatures. At higher temperatures, starting from the melting point, the crystallinity distribution can be well approximated by the Reinhold function. At lower temperatures, closer to the final solidification, the split Gauss function is a better approximation.

PL

Badano strukturę lamelarną kopolimerów etylen-1-okten podczas ich chłodzenia od temperatury topnienia do temperatury pokojowej. Parametry struktury wyznaczano na podstawie obliczeń modelowych, polegających na optymalnym dopasowywaniu teoretycznej krzywej rozpraszania SAXS, odpowiadającej założonemu modelowi struktury, do krzywej eksperymentalnej. W obliczeniach stosowano klasyczny model Hosemanna, zgodnie z którym wszystkie stosy lamelarne występujące w polimerze są statystycznie identyczne, oraz model zakładający niejednorodność struktury polimeru. Ten ostatni model zakładał, że stopień krystaliczności stosów jest zróżnicowany, a jego występowanie w objętości polimeru opisuje pewna funkcja rozkładu P(j). Badania wykazały, że nie jest możliwe uzyskanie dobrego dopasowania krzywych teoretycznych, opisanych zależnościami podanymi przez Hosemanna, do krzywych eksperymentalnych, co tym samym świadczy o nieadekwatności tego modelu w odniesieniu do badanych struktur. Zastosowanie drugiego modelu pozwoliło na uzyskanie bardzo dobrego dopasowania w całym zakresie rejestracji krzywych SAXS. Otrzymane wyniki świadczą o niejednorodnej strukturze stosów lamelarnych w badanych kopolimerach oraz o asymetrycznym charakterze rozkładu stopnia krystaliczności w stosach. W zakresie wysokich wartości temperatury, rozkład ten może być bardzo dobrze opisany za pomocą funkcji Reinholda. W zakresie niższych wartości temperatury, bliskich temperaturze końcowego zestalenia się kopolimeru, lepszym przybliżeniem jest tzw. składana funkcja Gaussa.

18

Wpływ warunków przetwórstwa na właściwości i strukturę regranulatu poli(tereftalanu etylenu) - rPET

Czarnecka-Komorowska D., Mencel K.

Inżynieria i Aparatura Chemiczna

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2014

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Nr 6

374--375

PL

W pracy oceniono wpływ parametrów technologicznych na właściwości przetwórcze i strukturę regranulatów z poli(tereftalanu etylenu) - PET. Zbadano wpływ temperatury i czasu suszenia na jakość regranulatów. Jako kryterium oceny jakości przyjęto wskaźnik szybkości płynięcia i lepkość istotną. Technikę DSC wykorzystano do oceny stopnia krystaliczności rPET. Stwierdzono, że najkorzystniejsze cechy (lepkość istotna równa 0,67 dl/g, stopień krystaliczności wynoszący ok. 27%) otrzymano podczas suszenia rPET w temperaturze 135°C w czasie 5 godzin.

EN

An influence of drying parameters on rheological properties and structure c polyethylene terephthalate regranulates produced by extrusion technology is presented in the paper. The assessment of drying temperature and time on regranulates quality was performed. As a criterion for assessing the rPE quality the melt flow index (MFI) and intrinsic viscosity of rPET were assumed. The DSC technique was used to evaluate the degree of rPET crystallinity. The drying temperature - 135°C and drying time - 5 hours turn out to be the optimal ones (intrinsic viscosity equal to 0.67 dl/g, crystallinity degree of ca. 27%).

19

The influence of silicate content on thermal stability of 2-line ferrihydrite and properties of its transformation products

Pieczara G., Rzepa G., Gaweł A.

Geology, Geophysics and Environment

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2014

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Vol. 40, no. 1

160--161

EN

Naturally occurring ferrihydrite (Fe5HO8 • 4H2O) is a poorly ordered iron (oxyhydr)oxide mineral, with non-stoichiometric composition and not fully understood structure. Because of its unique chemical and physical properties, such as low crystallinity, high surface area and surface reactivity, ferrihydrite plays significant role in e.g. inorganic weathering processes, biochemical cycling of iron and as a sorbent in various near-surface environments. Ferrihydrite is a metastable phase and transforms with time into stable oxides: goethite and/or hematite, through dissolution-reprecipitation and dehydration-rearrangement mechanisms, respectively. Ferrihydrite structure provides numerous sorption sites and for this reason substantial amounts of admixtures are present in its chemical composition. The most common and well documented impurities include silicate, phosphate, arsenate, sulphate, calcium, aluminum and organic compounds. These ions affect ferrihydrite composition, surface molecular structure and sorption properties. Silicate, probably the most important impurity, causes decreasing crystallinity of this nanomineral, modifies magnetic ordering and solubility. Thus, natural ferrihydrite distinctly differ from synthetic pure analogue. As it was previously shown, the association of Si with ferrihydrite surface hindered thermal transformation to hematite. The implications of this observation for the understanding of Si-ferrihydrite stability in geochemical systems are obvious. The aim of this work was determining of the influence of the Si/Fe ratio in ferrihydrites on its thermal transformation processes and the properties of the products. Ferrihydrite samples having different Si/Fe molar ratios: 0.00, 0.05, 0.10, 0.20, 0.25, 0.50, 0.75, 1.00, and 1.50, were obtained by reaction of Fe2(SO4)3 with NaOH in the presence of Na2Si03 at pH 8.2. After four-day incubation, dialysis and freeze-drying, the precipitates were characterized using X-ray powder diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Raman spectroscopy, and scanning electron microscopy (SEM). Then thermal analyses (DTA/DTG/TG) were performed. All of the ferrihydrites were heated from 30°C to 1000°C, at 10°C min-1 in flowing air, using hematite as inert material. After heating all the samples were again characterized by XRD and SEM-EDS methods. DTA curve of pure ferrihydrite shows typical dehydration endotherm at 160°C and. sharp exotherm at 350°C, attributed to hematite formation. Additional weak peaks at 550°C and 710°C were probably originated form decomposition of relic sulphate. The presence of Si in ferrihydrite appears to stabilize its structure and prevents conversion to hematite: the ferrihydrite-hematite transformation peak weakens and broadens and is shifted towards higher temperatures, up to ca. 900°C for high-Si materials. However, no simple linear relationship between silica content in ferrihydrite and the position of this peak has been found. X-ray diffraction patterns indicate that the main product of thermal transformation of all ferrihydrites is hematite (α-Fe2O3). For low-Si samples (Si/Fe < 0.20), a gradual broadening of 104, 214, 300, 110 hematite reflexes has been noticed, indicating the decrease of its crystallinity. On the other hand, for high-Si materials the broadening appears to be less distinct. Increasing Si/Fe molar ratio (≥ 0.10) in the initial material took an effect also in the appearance of a cristobalite-type oxide, the content of which increases drastically for the highest-Si samples. Additionally, the XRD pattern of the Si/Fe 0.10 sample reveals the presence of some spinel phase. Hematite originating from the heating of Si-free ferrihydrite forms quite large (up to 1 mm in size) isometric and prismatic crystals, often exhibiting pseudohexagonal shape. In contrast, the oxide particles become tenfold smaller even in the lowest-silicate material (Si/Fe = 0.05) and reveal pseudospheric morphology. In higher-silicate products (Si/Fe > 0.10) the crystallites are getting elongated and the elongation increases with increasing Si/Fe ratio. This preliminary study demonstrates that silicate content causes the retarding of ferrihydrite (thermal) transformation to hematite and affecting crystallinity of the latter. Even small Si admixture in the precursor reduces crystal size of the product. During roasting of low-Si ferrihydrites some Si probably enter the hematite structure, but higher-Si hematites cannot form and for this reason heating of high-Si ferrihydrites produces two-phase composition.

20

Prediction of the Durability of Composite Soft Ballistic Inserts

Fejdyś M, Cichecka M, Landwijt M, Struszczyk M

Fibres & Textiles in Eastern Europe

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2014

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Vol. 22, no. 6 (108)

81--89

EN

The main goal of this research was to develop a method of predicting the durability of soft ballistic inserts made of a high-strength composite based on polyethylene ultra-high molecular weight (UHMWPE) fibres. The research presents a program of tests on the simulated use of composite ballistic inserts elaborated in order to predict the durability as well as changes in the ballistic, physical and mechanical properties occurring due to conditions of use. The research program took the following three procedures of the aging simulation of the ballistic inserts into account: procedure 1 – applying a mechanical load to the insert; procedure 2 – applying a mechanical load along with a temperature cycle to the insert; procedure 3 – applying a mechanical load, temperature cycle and liquid solution simulating human perspiration to the insert. The procedures were verified experimentally by examining inserts made out of soft composite polyethylene Dyneema® SB 21. Also verification by means of the Snedecor’s F-test was carried out. It was shown that the effect of mechanical loading, temperature cycling, and the solution simulating human perspiration influences the progress of degradation of the polyethylene material. The research work included testing new ballistic inserts made of a polyethylene composite, as well as ones subjected to simulation ageing. To investigate the correlation between the natural ageing process and the simulated one, ballistic inserts used under natural conditions for 5, 7, 9 and 13 years were examined. Selected samples were used for the determination of mechanical and ballistic property variation as well as changes in their chemical structure. Changes in the microstructure of the ballistic material were assessed by DSC analysis and infrared spectroscopy (FTIR-ATR).

PL

Głównym celem realizowanych prac było opracowanie metody prognozowania trwałości miękkich wkładów balistycznych wykonanych z wysokowytrzymałego kompozytu na bazie polietylenu o bardzo dużym ciężarze cząsteczkowym(UHMWPE). W artykule przedstawiono program badań symulacji użytkowania kompozytowych wkładów balistycznych, który opracowano celem prognozowania trwałości, a tym samym przewidywania zmian parametrów balistycznych, fizyko-mechanicznych wkładów ochronnych, zachodzących pod wpływem warunków eksploatacji. Wnioskowanie odnośnie zmian stanu technicznego wyrobów balistycznych pod wpływem warunków przechowywania i użytkowania wymagało zweryfikowania opracowanej metodyki badawczej i przeprowadzenia badań uwzględniających metodę przyspieszonego starzenia. W ramach pracy badaniom poddano nowe pakiety balistyczne wykonane z kompozytu polietylenowego, jak również poddane starzeniu laboratoryjnemu. Celem zbadania korelacji między procesami starzenia naturalnego i symulowanego zbadano pakiety balistyczne użytkowane w warunkach naturalnych przez 5, 7, 9 i 13 lat. Dla wytypowanych próbek zostały przeprowadzone badania właściwości mechanicznych i balistycznych oraz zmian ich struktury chemicznej. Zmiany w strukturze materiałów balistycznych oceniono za pomocą metod: analizy termicznej DSC, spektroskopii w podczerwieni (FTIR-ATR).