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    Tytuł:
    Determination of degree of deacetylation of chitosan - comparision of methods
    Autorzy:
    Czechowska-Biskup, Renata
    Jarosińska, Diana
    Rokita, Bożena
    Ulański, Piotr
    Rosiak, Janusz M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1035372.pdf
    Data publikacji:
    2012
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    degree deacetylation
    methods
    Opis:
    Degree of deacetylation (DD) is one of the main parameters characterizing chitosan. The most precise measurements of DD require sophisticated equipment (NMR spectrometer), not available at many laboratories worldwide working on chitosan. There is a need for low-cost, simple, yet sturdy and reliable methods and procedures for DD determination. The aim of this work was to test and compare – on the same set of chitosan samples - a few of the existing analytical techniques and provide recommendation for selecting DD determination methods. Tests were performed on four chitosans of nominal DD in the range 70 - 95%. Three different methods of titration, two different methods of spectroscopy UV / Vis and infrared spectroscopy using various calculation approaches were used. The results are summarized and compared with values obtained by 1H NMR, considered as the reference method. Moreover, evaluation of the ease of performance and availability of reagents in the given methods was performed. On that basis, recommendations for selection of DD determination methods were formulated.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2012, 17; 5-20
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of chitosan flake deacetylation degree on orthophosphate sorption efficiency from aqueous solutions
    Autorzy:
    Bugajska, Paula
    Filipkowska, Urszula
    Jóźwiak, Tomasz
    Kuczajowska-Zadrożna, Małgorzata
    Powiązania:
    https://bibliotekanauki.pl/articles/1034433.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    deacetylation degree
    orthophosphate
    sorption
    Opis:
    The article presents the effectiveness of orthophosphate sorption from aqueous solutions depending on the deacetylation degree of chitosan flakes. The first stage of the research was to determine the pH value at which the sorption process was the most effective (from the pH range 2–11). In the second stage, research was carried out to determine the maximum sorption capacities of chitosan with deacetylation degrees of 75%, 85% and 90% in relation to PO43-. The highest effectiveness of orthophosphate removal on chitosan, regardless of its deacetylation degree, was obtained at pH 4. At pH 2 and 3, the chitosan flakes dissolved. This study showed that the sorption effectiveness of phosphorus compounds depends on the deacetylation degree of chitosan. Along with the increase in deacetylation degree, the sorption capacity of chitosan also increases in relation to orthophosphates. It is related to the higher number of amino groups in the structure of chitosan, which are responsible for the sorption of pollutants in the form of anions. The maximum sorption capacity of chitosan-DD = 75% in relation to biogen was 5.13 mg/g, chitosan-DD = 85% was 5.65 mg/g, and chitosan-DD = 90% was 5.91 mg/g. After 60 minutes, the desorption process had begun and was most likely caused by an increase in the pH of the solution. Due to chitosan's ability to neutralise the sample and the associated risk of desorption, the time of sorbent contact with sewage cannot be longer than 60 minutes.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2018, 23; 33-44
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of the deacetylation degree of chitosan in the form of flakes on the effectiveness of nitrates v sorption from aqueous solutions
    Autorzy:
    Jóźwiak, Tomasz
    Filipkowska, Urszula
    Bugajska, Paula
    Kuczajowska-Zadrożna, Małgorzata
    Mielcarek, Artur
    Powiązania:
    https://bibliotekanauki.pl/articles/1034527.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    deacetylation degree
    nitrate
    sorption
    Opis:
    The influence of the degree of deacetylation of chitosan from the range of DD = 75–90% on the effectiveness of sorption of nitrates from aqueous solutions was investigated. The scope of the research included: determining the effect of pH on the effectiveness of N-NO3 binding on chitosan sorbents and determining the sorption capacity of chitosan sorbents with different degrees of deacetylation after 5, 15, 30 and 60 minutes. The effectiveness of sorption of nitrates on chitosan sorbents increased in the series DD=75% < DD=85% < DD=90%. Regardless of the degree of deacetylation, the sorption effectiveness of nitrates on chitosan was the highest at pH 4. The amount of nitrate-related sorbents was the highest after 30 min of sorption. A process time which was too long resulted in desorption of nitrates. The maximum sorption capacity for chitosan with the degree of deacetylation DD = 75, 85 and 90% was 0.59 mg N-NO3/g, 0.60 mg N-NO3/g and 0.87 mg N-NO3/g, respectively.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2018, 23; 88-96
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Isolation and characterization of chitin from shells of the freshwater crab potamon algeriense
    Autorzy:
    Fadlaoui, Soufiane
    El Asri, Ouahid
    Mohammed, Lakrat
    Sihame, Addou
    Omari, Abdelouadoud
    Melhaoui, Mohammed
    Powiązania:
    https://bibliotekanauki.pl/articles/1034352.pdf
    Data publikacji:
    2019
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    Chitin
    Potamon algeriense
    chitosan
    deacetylation
    freshwater crab
    Opis:
    This work presents, for the first time, the extraction and characterization of chitin from the shell of the freshwater crab species Potamon algeriense with a standardized and revised chemical method. Chitin and chitosan were isolated following demineralization, deproteinization, decolouration (raw chitin), and deacetylation (chitosan). After boiling, drying, and grinding, 62.12% of the ground shell was obtained. A yield of 40.92% was obtained after demineralization of ground crab shell, while after the deproteinization process 8.74% was obtained. After decolourization, 8.27% of raw chitin was obtained, and the final amount of chitosan extracted from the crab shells was approximately 5.89%. We also characterized the isolated chitin by determining its physicochemical properties using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA).
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2019, 24; 23-35
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of chitosan deacetylation degree on reactive black 5 sorption efficiency from aqueous solutions
    Autorzy:
    Jóźwiak, Tomasz
    Filipkowska, Urszula
    Szymczyk, Paula
    Kuczajowska-Zadrożna, Małgorzata
    Mielcarek, Artur
    Zyśk, Michał
    Powiązania:
    https://bibliotekanauki.pl/articles/1034679.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    Reactive Black 5
    chitosan
    deacetylation degree
    sorption
    Opis:
    In the paper sorption capacity of chitosan having a deacetylation degree DD=75%, DD=85% and DD=90% relatively to the Reactive Black 5 were compared. Studies on the effectiveness of the dye sorption were carried out in a wide pH range – from 3 to 11. For each of the tested chitosan sorbents, sorption capacity has been determined. The results were described by isotherms Freundlich and Lagmuir isotherms, and a double Langmuir isotherm. Sorption of Reactive Black 5 most efficiently occurred at pH 4. At pH <4 chitosan sorbents underwent dissolution, regardless of the degree of deacetylation. The efficiency of dye sorption increased with the degree of deacetylation. The sorption capacity calculated after 12 h of the chitosan sorption with DD=75%, DD=85% and DD =90% was, relatively to the Reactive Black 5, respectively 433.03 mg/g and 464.52 mg/g and 532.14 mg/g. The impact of the deacetylation degree on pHZPC (zero point of charge) of the sorbent was also examined. Along with the increase in the deacetylation degree the value of chitosan pHZPC increased as well and at DD=75% DD=85% and DD=90%, pHZPC amounted respectively 7.6, 7.7 and 7.8.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2016, 21; 83-92
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of gamma radiation and physicochemical treatment to improve the bioactive properties of chitosan extracted from shrimp shell
    Autorzy:
    Aktar, J.
    Hasan, Z.
    Afroz, T.
    or-Rashid, H.
    Pramanik, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/148197.pdf
    Data publikacji:
    2017
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    chitosan
    gamma radiation
    degree of deacetylation
    antimicrobial activity
    Opis:
    The aim of this study is to exploit a suitable chitosan extraction method from the chitin of indigenous shrimp shells by employing different physicochemical treatments and to improve different bioactive properties of this extracted chitosan (CS) by applying gamma radiation. Chitin was prepared from shrimp shell by pretreatment (deproteination, demineralization and oxidation). Chitosan was extracted from chitin by eight different methods varying different physicochemical parameters (reagent concentration, temperature and time) and assessed with respect to the degree of deacetylation, requirement of time and reagents. The method where chitin was repeatedly treated with 121°C for 30 min with 20 M NaOH, produced the highest degree of deacetylation (DD) value (92%) as measured by potentiometric titration, with the least consumption of time and chemicals, and thus, selected as the best suitable extraction method. For further quality improvement, chitosan with highest DD value was irradiated with different doses (i.e., 5, 10, 15, 20 and 50 kGy) of gamma radiation from cobalt-60 gamma irradiator. As the radiation dose was increased, the molecular weight of the wet irradiated chitosan, as measured by the viscosimetric method, decreased from 1.16 × 105 to 1.786 × 103 , 1.518 × 103 , 1.134 × 103 , 1.046 × 103 and 8.23 × 102 dalton, respectively. The radiation treatment of chitosan samples increased the antimicrobial activity signifi cantly in concentration dependent manner on both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria, as determined by the well-diffusion method. Four to fi ve percent wet chitosan treated with a radiation dose range of 5.0–10.0 kGy rendered the highest antimicrobial activity with least energy and time consumption. Solubility, water binding capacity (WBC) and fat binding capacity (FBC) also improved due to irradiation of chitosan.
    Źródło:
    Nukleonika; 2017, 62, 4; 245-251
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The inhibition of human platelet aggregation by a low-molecular weight chitosan
    Autorzy:
    Drozd, Natalia N
    Logvinova, Yulia S.
    Shagdarova, Balzhima Ts.
    Il’ina, Alla V.
    Varlamov, Valery P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1034373.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    deacetylation degree
    depolymerisation
    molecular weight
    platelet aggregation
    Opis:
    Chitosan derivatives were obtained by chemical (MW of 6 kDa, DD 99% - Ch6/99; MW13 kDa, DD 98% - Ch13/98) and enzymatic (MW of 5 kDa, DD 85% - Ch5/85; MW of 10 kDa, DD 85% - Ch10/85) depolymeri-sation of chitosan with a MW of 334 and 1000 kDa. Chitosan derivatives (almost identical MW pairs and different DD) possessed insignificant an-ticoagulant activity, did not promote human platelet aggregation and re-duced ADP or collagen-induced platelet aggregation. The studied sam-ples at a concentration of 2 mg/ml reduced the aggregation of platelets more than twice induced in 2x10-6M and 1x10-5M concentrations; at weak activation in 2x10-6M, the Ch10/85 sample was the most effective. The Ch6/99 and Ch13/98 samples were 20 times more effective at the inhibi-tion of collagen-induced platelet aggregation than the Ch10/85 sample. The latter can be explained by the greater value of positive charge (DD) and polydispersity (Mw/Mn) of chitosan samples obtained by chemical de-polymerisation
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2018, 23; 55-65
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of chitosan molecular weight and degree of deacetylation on membrane physicochemical and separation properties in ethanol dehydration by the vapour permeation process
    Autorzy:
    Gnus, Małgorzata
    Powiązania:
    https://bibliotekanauki.pl/articles/1034007.pdf
    Data publikacji:
    2020
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    degree of deacetylation
    molecular weight
    separation properties
    vapour permeation
    Opis:
    Membranes were prepared using three chitosans with different molecular weights and degrees of deacetylation. The influence of chitosan features on membrane physicochemical properties, i.e. degree of swelling, contact angle and tensile strength, as well as membrane separation properties in ethanol dehydration by the vapour permeation process are discussed. The conducted experiments showed that an increase in the chitosan molecular weight led to an increase in the membrane surface contact angle concomitant with a decrease in the material selectivity coefficient. On the other hand, an increase in the chitosan degree of deacetylation caused a reduction in ethanol and improved the water permeate flux. There was greater selectivity in the test process for membranes prepared from chitosan with the lowest molecular weight.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2020, 25; 79-93
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Express analysis of chitosan and its derivatives by gel electrophoresis
    Autorzy:
    Konovalova, Mariya
    Shagdarova, Balzhima Ts.
    Zubov, Vitaliy
    Svirshchevskaya, Elena
    Powiązania:
    https://bibliotekanauki.pl/articles/1034210.pdf
    Data publikacji:
    2019
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    agarose gel electrophoresis
    chitosan
    chitosan derivatives
    degree of deacetylation
    molecular weight
    Opis:
    Chitosan is one of the most promising polymers for biomedical applications due to its unique properties, such as its biocompatibility, low toxicity, biodegradation, and the presence of reactive amino and hydroxyl groups. Analysis of physicochemical properties of chitosan and its derivatives is a time-consuming process and requires expensive equipment and large amounts of the sample. This paper proposes a method for express analysis of the molecular weight (MW), the degree of deacetylation (DD), the substitution degree (SD), and the charge of chitosan and its derivatives using agarose gel electrophoresis under acidic and neutral conditions with Coomassie staining. Positively charged chitosan samples required acidic Tris Acetate-EDTA (TAE) buffer to move in the gel. The electrophoretic mobility of chitosan depended on MW, DD, SD, and the chitosan charge. Based on the dependences obtained by the proposed method, the MW and DD of commercial chitosan samples were determined. Express analysis of chitosan and its derivatives in agarose gel can be used to monitor the reactions of chitosan modification and to analyse samples with unknown characteristics.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2019, 24; 84-95
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of chitin structure on its enzymatic deacetylation
    Autorzy:
    Jaworska, M.
    Roberts, G.A.F.
    Powiązania:
    https://bibliotekanauki.pl/articles/952676.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    chitin
    chitin deacetylase
    enzymatic deacetylation
    structure
    crystallinity
    conformation
    chityna
    krystaliczności
    struktura
    Opis:
    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.
    Źródło:
    Chemical and Process Engineering; 2016, 37, 2; 261-267
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The effect of DNA methyltransferase and histone deacetylase inhibitors on αKlotho gene expression in bladder cancer T24 cell line
    Wpływ inhibiotorów metylotransferaz DNA oraz deacetylaz białek histonowych na kspresję genu αKlotho w komórkach raka pęcherza moczowego linii T24
    Autorzy:
    Szymczyk, Agnieszka
    Forma, Ewa
    Powiązania:
    https://bibliotekanauki.pl/articles/1032842.pdf
    Data publikacji:
    2014
    Wydawca:
    Łódzkie Towarzystwo Naukowe
    Tematy:
    bladder cancer
    klotho
    dna methylation
    histone deacetylation
    rak pęcherza moczowego
    metylacja dna
    deacetylacja histonów
    Opis:
    Introduction: αKlotho gene was originally identified as a putative agesuppressing gene in mice. Recently it is known that αKlotho gene functions as a tumor suppressor in many types of cancer, including breast, pancreas, gastric, colon, lung and cervical cancer. The downregulation of αKlotho expression was associated with CpG hipermethylation of promoter region and histone deacetylation. Bladder cancer is the most common cancer of the urinary tract in Polish population. The aim of this study was the analysis of the effect of DNA methyltransferase and histone deacetylase inhibitors on αKlotho gene expression in bladder cancer cells. Materials and methods: In this study T24 bladder cancer cell line was used. The analysis of the effect of DNA methyltransferase and histone deacetylase inhibitors on αKlotho gene expression was performed using Real Time PCR method with TaqMan probes. To determine the methylation profile of αKlotho gene promoter region quantitive Methylation-Specific Polymerase Chain Reaction technique was used. Results: The treatment of T24 cells with DNA methyltransferase inhibitor (AZA) restored the expression of αKlotho gene. After AZA treatment, the methylation level of CpG island in the promoter region of αKlotho gene was nearly half lower (p<0.05) than control cells. In case of the treatment of T24 cells with histone deacetylase inhibitor (TSA) we did not observe any changes in αKL gene expression in respect to the control cells. Treatment cells with both the inhibitors led to the significant increase of mRNA αKlotho gene expression level (p<0.001). Conclusions: The changes in αKlotho gene expression on mRNA level are associated with epigenetic changes.
    Wstęp: Gen αKlotho pierwotnie zidentyfikowany został u myszy jako gen, którego ekspresja wpływa na długość ich życia. Obecnie wiadomo, że αKlotho spełnia funkcję genu supresorowego w przypadku wielu typów nowotworów, m.in. w raku piersi, trzustki, żołądka, płuc, okrężnicy i raku szyjki macicy. Wykazano, że spadek ekspresji genu αKlotho związany jest z hipermetylacją wysp CpG w obrębie regionu promotorowego oraz deacetylacją histonów. Rak pęcherza moczowego jest najczęściej występującym nowotworem układu moczowego w Polsce. Celem prowadzonych badań była analiza wpływ inhibitorów metylotransferaz DNA oraz deacetylaz białek histonowych na ekspresję genu αKlotho w komórkach raka pęcherza moczowego. Materiały i metody: Materiał do badań stanowiła linia komórek raka pęcherza moczowego T24. Analizę wpływu inhibitorów metylotransferaz DNA oraz deacetylaz białek histonowych na ekspresję genu αKlotho prowadzono techniką Real Time PCR z użyciem sond fluorescencyjnych TaqMan. Ocenę stopnia metylacji regionu promotorowego badanego genu prowadzono przy użyciu techniki ilościowego MSP-PCR (ang. Methylation-Specific Polymerase Chain Reaction). Wyniki: W wyniku traktowania komórek linii T24 inhibitorem metylotransferaz DNA (AZA) obserwowano przywrócenie ekspresji genu αKlotho. W porównaniu do komórek kontrolnych, komórki traktowane 5-aza-2′-deoksycytydyną wykazywały blisko o połowę niższy stopień metylacji wysp CpG w regionie promotorowym genu αKlotho (p<0,05). W wyniku traktowania komórek inhibitorem deacetylaz białek histonowych (TSA) nie obserwowano zmian w ekspresji genu αKL. Zastosowanie obu inhibitorów prowadziło do istotnego wzrostu ekspresji genu αKlotho na poziomie mRNA (p<0,001). Wnioski: Zmiany ekspresji genu αKlotho na poziomie mRNA związane są ze zmianami we wzorze modyfikacji epigenetycznych.
    Źródło:
    Folia Medica Lodziensia; 2014, 41, 2; 111-119
    0071-6731
    Pojawia się w:
    Folia Medica Lodziensia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of FTNIR Spectroscopy for Evaluation of the Degree of Deacetylation of Chitosan Fibres
    Zastosowanie spektroskopii w bliskiej podczerwieni do oznaczania stopnia deacetylacji włókien chitozanowych
    Autorzy:
    Biniaś, W
    Biniaś, D
    Powiązania:
    https://bibliotekanauki.pl/articles/233601.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
    Tematy:
    FTNIR
    deacetylation degree
    dibutyrylchitin fibres
    chitosan fibres
    mikroporowate włókna
    stopień deacetylacji
    włókna dibutyrylochitynowe
    włókna z chityny regenerowanej
    Opis:
    Microporous dibutyrylchitin (DBC) fibres spun from DBC solution in ethyl alcohol were subjected to alkaline treatment in potassium hydroxide aqueous solutions. Alkaline treatment with a diluted KOH solution at room temperature causes a gradual decrease in the number of butyric groups, which leads to obtaining fibres from the regenerated chitin. Further treatment of the fibres with a saturated KOH solution at an elevated temperature produces chitosan fibres with various degrees of deacetylation (DD), values which depend on the duration of the deacetylation process. The course of the deacetylation process was evaluated on the basis of the results of the near infrared (NIR) spectroscopy measurements. The method suggested allows for the precise measuring of the level of conversion without additional mechanical treatment (rubbing, powdering). A prepared sample is placed in the measuring chamber of the spectroscope. The FTNIR spectra of the fibres examined have characteristic bands whose analysis allows for clear determination of the level of deacetylation during chemical treatment.
    Mikroporowate włókna z dibutyrylochityny formowane z roztworu sporządzonego w alkoholu etylowym, poddano alkalicznej obróbce przy zastosowaniu roztworów wodorotlenku potasu. Obróbkę alkaliczną włókien dibutyrylochitynowych prowadzono w temperaturze pokojowej w 5% roztworach wodorotlenku potasu. Obróbka ta spowodowała stopniowy spadek ilości grup butyrylowych i uzyskanie włókien z chityny regenerowanej. W dalszej kolejności otrzymane włókna z chityny regenerowanej poddano alkalicznej obróbce w nasyconych roztworach wodorotlenku potasu, która spowodowała stopniowy spadek ilości grup acetylowych prowadzący do uzyskania włókien chitozanowych o zróżnicowanym stopniu deacetylacji. Proces przemiany we włókna chitynowe oraz chitozanowe przebiega z różną szybkością w zależności od czasu, temperatury obróbki oraz stężenia wodorotlenku potasu. Oznaczanie stopnia deacetylacji, a tym samym przebieg procesu deacetylacji włókien oceniano za pomocą spektroskopii w bliskiej podczerwieni (NIR). Zastosowana metoda oceny stopnia deacetylacji włókien pozwala na dokładny pomiar stopnia przereagowania bez dodatkowej obróbki mechanicznej (ucierania proszkowania). Badaną próbkę umieszcza się w komorze spektrofotometru. Widma w zakresie bliskiej podczerwieni posiadają charakterystyczne pasma, których analiza w sposób jednoznaczny pozwala określić stopień deacetylacji włókien.
    Źródło:
    Fibres & Textiles in Eastern Europe; 2015, 2 (110); 10-18
    1230-3666
    2300-7354
    Pojawia się w:
    Fibres & Textiles in Eastern Europe
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of Raman Spectroscopy for Evaluation of Chemical Changes in Dibutyrylchitin Fibres
    Zastosowanie spektroskopii Ramana do oceny zmian chemicznych zachodzących we włóknach dibutyrylochitynowych
    Autorzy:
    Biniaś, D.
    Biniaś, W.
    Janicki, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/233215.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
    Tematy:
    Raman spectra
    dibutyrylchitin fibres
    deesterification degree
    chitin fibres
    deacetylation degree
    spektroskopia Ramana
    włókna dibutyrylochitynowe
    włókna chitynowe
    stopień deacetylacji
    Opis:
    Microporous dibutyrylchitin (DBC) fibres formed by means of a dry-wet method were treated with aqueous solutions of potassium hydroxide. By applying various parameters of the alkaline treatment, fibres can be transformed into fibres from regenerated chitin or even into chitosan fibres. In the first stage, with the application of 5% KOH solutions and temperatures ranging from 20 to 90 °C, fibres from regenerated chitin were obtained. The subsequent treatment stage with saturated KOH solutions and the temperature range 70 - 140 °C resulted in obtaining fibres from chitosan with different deacetylation degrees.Structural changes in the fibres occurring in the course of their chemical treatment were analysed using RAMAN spectroscopy. Raman spectra were next mathematically processed by means of GRAMS software within the range 1800 - 820 cm-1 in order to evaluate the changes quantitatively. A new method is described for the determination of butyrylation and deacetylation degrees of dibutyrylchitin, chitin and chitosan. Analysis of the fibres obtained carried out by means of RAMAN spectroscopy proves that in the process gradual degradation of the polymer chains takes place.
    Mikroporowate włókna dibutyrylochitynowe otrzymane w wyniku przędzenia metodą sucho mokrą poddano alkalicznym obróbkom przy zastosowaniu roztworów wodorotlenku potasu. W pierwszym etapie uzyskano z włókien dibutyrylochitynowych włókna z chityny regenerowanej przy zastosowaniu 5% roztworów KOH w temperaturach z zakresu 20 – 90 °C. W kolejnym etapie, w wyniku zastosowania nasyconych roztworów KOH w wysokich temperaturach z zakresu 70 – 140 °C, uzyskano włókna chitozanowe o różnicowanych stopniach deacetylacji. Zachodzące w czasie poszczególnych etapów obróbek obserwowano zmiany strukturalne przy zastosowaniu spektroskopii Ramana. W celu przeprowadzenia analizy ilościowej procesów obróbki alkalicznej wykonano rozkłady widm FT Raman przy zastosowaniu oprogramowania „GRAMS” w zakresie 1800-820 cm-1. Na podstawie wykonanych rozkładów widm FT Raman dla badanych serii podjęto próbę obliczenia stopnia butyrylacji oraz stopnia deacetylacji włókien. Na podstawie badań ramanowskich stwierdzono częściową degradację łańcucha polimeru.
    Źródło:
    Fibres & Textiles in Eastern Europe; 2016, 4 (118); 27-38
    1230-3666
    2300-7354
    Pojawia się w:
    Fibres & Textiles in Eastern Europe
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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