NATURAL POLYMERS MU SCI 7 2018 1 NATURAL POLYMERS Polysaccharide II CELLULOSE 3 Dr. Ladislav Pospíšil January 7/2018 Cellulose is the most widespread BIOPOLYMER on Earth, up to 1,5×109 tons per annum is arising Time schedule January 2018/6 NATURAL POLYMERS MU SCI 6 2018 2 LECTURE SUBJECT 1 Introduction to the subject – Structure & Terminology of nature polymers, literature 2 Derivatives of acids – natural resins, drying oils, shellac 3 Waxes 4 Plant (vegetable) gums, Polyterpene – natural rubber (extracting, processing and modification), Taraxacum_kok-saghyz 5 Polyphenol – lignin, humic acids 6 Polysaccharides I – starch 7 Polysaccharides II – celullosis 8 Protein fibres I 9 Protein fibres II 10 Casein, whey, protein of eggs 11 Identification of natural polymers Laboratory methods of natural polymers’ evaluation January 7/2018 NATURAL POLYMERS MU SCI 7 2018 3 Cellulose ZnCl2 vulcanized fiber H2SO4 & HNO3 Cellulose nitrate Gun cotton EXPLOSIVES Colloidal cotton (collodium) Celluloid Films Varnishes Acetic acid anhydride Cellulose Acetate Films Foils Varnishes Acetate rayon/silk Acetic & butyric acid anhydrides Cellulose Acetato butyrate Foils Plastics January 7/2018 NATURAL POLYMERS MU SCI 7 2018 4 Cellulose NaOH & CH3Cl & CH3CH2Cl or Benzylchloride & monochloracetic acid NaOH & CS2 Cellulosedithiocarbamate Cooper hydroxide Ammonium Complex (Schweitzer reagent) Viscose •Methylcellulose •Ethylcellulose •Benzylcellulose •Carboxymethylcellulose •Glue •Thickener •Consume Goods Viscose Rayon Cellophane Cuprammonium Rayon Cellulose Modification I PRODUCT PROPERTIES USE Regenerated Cellulose Viscose Similar to native Cellulose Fibres Cellophane Transparent, colourless Foils for Foodindustry and technical Use Cellulose Acetate Transparent, colourless, soluble in organic Solvents Varnishes ,Glue, Foils , Cine-film (HISTORY), Fibres , ……… Cellulose Propionate Similar to Cellulose Acetate, but higher temperature Resistance and Strength Thermoplastic for engineering Parts and electrotechnics Cellulose Acetobutyrate Gloss, dimensional Stability, Light exposure Resistance Varnishes, Injection Moulding (Glasses Frames, Furnace handles etc.) January 7/2018 NATURAL POLYMERS MU SCI 7 2018 5 Cellulose Modification II PRODUKT VLASTNOST POUŽITÍ Cellulose Nitrate Nitration level accordingly, e.g. Camphor plasticized > Celluloid Varnishes, Foils , Thermoplastic, EXPLOSIVES Methylcellulose, ethylcellulose Methylation level accordingly soluble in organic Solvents or in Water also, film forming, emulsifying Agent Glues, emulsifying Agent, textile Sizing Benzylcellulose As the Methylcellulose and ethylcellulose Varnishes, Electroinsulation Carboxymethylcellulose Colloidal and emulsifying Properties, soluble in hot Water, Sodium salt is soluble in the cold Water also Glues, textile Sizing, protective Colloid, Thickener January 7/2018 NATURAL POLYMERS MU SCI 7 2018 6 Cellulose Modification III PRODUKT VLASTNOST POUŽITÍ Hydroxyethylcellulose Film forming, soluble in Water and in the Mixtures Water + ethanol Hair spray, Thickener for Paints (THIXOTROPIC EFFECT) January 7/2018 NATURAL POLYMERS MU SCI 7 2018 7 Cuprammonium Rayon January 7/2018 NATURAL POLYMERS MU SCI 7 2018 8 • a Cellulose Content must be very high, > 95 %w/w and more • So that so called LINTRES (Cotton) having the a Cellulose Content up to 99 % w/w are used for this Technology January 7/2018 NATURAL POLYMERS MU SCI 7 2018 9 Schweitzers reagent = Kuamox img297.jpg The Substance mCuSO4.nCu(OH)2 is used as the basic Salt and is prepared as follows: The following Reaction course is supposed during Dissolution of Cellulose in the Cooper hydroxide Ammonium Complex (Schweitzers reagent): January 7/2018 NATURAL POLYMERS MU SCI 7 2018 10 img220.jpg Another possibilities to express the Reactions course during Cellulose Dissolution are presented here (above & bellow) Viscose Fibre 1.ALKALICELLULOSE –b and g Cellulose are separated by PRESSING > THE Rest is a Cellulose (18 % w/w NaOH is used for this Process) •NaOH is separated from Hemicelluloses and lower MW Celluloses by Dialysis •a Cellulose Content should be 90 – 92 %w/w for Rayon and > 95 % w/w for Tire cord fabric 2. XANTOGENATION •ALKALICELLULOSE + CS2 > SOLUTION 3.Wet Spinning to Coagulant (Precipitant) January 7/2018 NATURAL POLYMERS MU SCI 7 2018 11 January 7/2018 NATURAL POLYMERS MU SCI 7 2018 12 img303.jpg img302.jpg img304.jpg ALKALICELLULOSE ß Xantogenation REGENERATION SIDE REACTIONS Carbonylsulfide January 7/2018 NATURAL POLYMERS MU SCI 7 2018 13 img217.jpg This Reaction accordingly Cellulose forms with NaOH chemical Compound of alcoholates Type, in this Case CELLULOSATE: The Reaction of NaOH with basic Cellulose Chain part (GLUCOSE) can go via two following Schemes: January 7/2018 NATURAL POLYMERS MU SCI 7 2018 14 Xanthogenate_Cellulose_Structural_Formula_V1_svg.png XANTOGENTION CELLULOSE Carbons C6 are the most reactive, because having the lowest Steric Hindrance! TRISUBSTITUTED Cellulose Derivatives is the maximal Substitution, because of Steric Hindrance of reaction possible Sites January 7/2018 NATURAL POLYMERS MU SCI 7 2018 15 img714.jpg img715.jpg Schweitzers Reagent ALKALICELLULOSE CELLULOSE XANTOGENATE REGERATED CELLULOSE Comparision of Cuprammonium Rayon and Viscose Fibre January 7/2018 NATURAL POLYMERS MU SCI 7 2018 16 img590.jpg img591.jpg It was approx. 50 years ago: • Viscose Fibre was the Dominant Manmade type • Technology was developed up to almost Perfection Why is it today the only minor Fibre one? Technology INDUSTRIAL RAYON Scheme of the Continuous Spinning of Viscose Why is it today the only minor Fibre one? January 7/2018 NATURAL POLYMERS MU SCI 7 2018 17 •Technological demanding character –Too much Technological production Steps –Time consuming, Process is very long-lasting –Solvents’ Regeneration is necessary •Expences –Technology has many complicated Machines –Solvents’ Regeneration •Environment Protection –CS2 –Europe didn’t invest to e.g. Multi-skin Buildings and/or CS2 Adsorption or Absorption January 7/2018 NATURAL POLYMERS MU SCI 7 2018 18 CORE with different Structure SKIN Slowly Precipitation (Coagulation) > uniform Structure in Fibre Crosscut > HIGHER TENSILE STRENGHT > TIRE CORD img117.jpg Fibre Crosscut Scheme: 1. Fibre with Core 2. Fibre WITHOUT CORE Current us of VISCOSE CORD January 7/2018 NATURAL POLYMERS MU SCI 7 2018 19 •CORD = Rayon of extremly high TENSILE STRENGHT •Manufacture of CARBON FIBRES: –PAN (polyacrylonitrile) – the main Raw Material today –Black Coal-tar pitch (By-product in Production of Coke (Coking plant)) – the minor Raw Material today –Viscose Cord – the IGNORED Raw Material today •Viscose Cord – Tire carcass (formerly) • January 7/2018 NATURAL POLYMERS MU SCI 7 2018 20 netkanka viskoza 200x.jpg netkanka viskoza 1kxM.jpg Viscose Rayon Nonwoven Textile January 7/2018 NATURAL POLYMERS MU SCI 7 2018 21 netkanka viskoza 200x.jpg netkanka viskoza 5kx.jpg Viscose Rayon Nonwoven Textile Cellulose hydrolysis 1 January 7/2018 NATURAL POLYMERS MU SCI 7 2018 22 str 161.jpg Catalysed mainly by INORGANIC ACIDS (HCl, H2SO4) CHAIN Scission Cellulose hydrolysis 2 January 7/2018 NATURAL POLYMERS MU SCI 7 2018 23 It is sufficient to prepare Cellulose by 1 % Solution of these Acids and dry at 60 – 70 °C The Result is so called HYDROCELLULOSE, having the lower MW > the Reaction see the last Picture HYDROCELLULOSE has other Properties: • It gives the REDUCING SACCHARIDES REACTION > the ENDGROUPS after Scission are ALDEHYDES •It has higher Solubility in Alkalis (NaOH), MW accordingly Catalysed mainly by INORGANIC ACIDS (HCl, H2SO4) Cellulose Solvents January 7/2018 NATURAL POLYMERS MU SCI 7 2018 24 The Derivatives of Cellulose are presented in this Table mostly! str 166.jpg This was found out be me in the Original literature only! The latest Trends: • IONIC LIQUIDS, • METLS OF SOLTS (e.g. ZnCl2 . 4H2O. Dissolved Substance Solvent What were the REASONS to start the Production of Viscose Rayon? •ENDLESS FIBER •Substitution of the Natural Silk •It can coloured in Mass •Possibilities of the various Diameters •Possibility to control the Mechanical Properties by Drawing etc. •Utilisation the other sorts of Cellulose then the Cotton only •??????????????? January 7/2018 NATURAL POLYMERS MU SCI 7 2018 25 Oxidised Cellulose •Company SYNTHESIA Pardubice (Czech Republic) > Trade name OKCEL –POWDER –TEXTILE •Use –Medicine – haemostatic (styptic) agent, absorbable Covering of the open wound –Technical –Varnishes, foils (films), …….. •Production Technology –Cotton Oxidation •H2O2, HNO3, Hypochlorite, … •Oxidised Cellulose Types (Kinds) –Changes of the main Chain done by Oxidation –Different Solubility in Water and in NaOH water Solution • January 7/2018 NATURAL POLYMERS MU SCI 7 2018 26 January 7/2018 NATURAL POLYMERS MU SCI 7 2018 27 OKCEL: Humane Medicine and Surgery OKCEL® is a quality oxidized cellulose based haemostat designed for controlling internal bleeding during surgical procedures, includig minimally invasive procedures. It is perfectly accepted by organism and fully absorbed. Thanks to protection against infection, OKCEL® products help with the tissue regeneration and thus enhance the healing effect. OKCEL® products are available in various sizes and shapes and can be customized to meet individual customer requirements. OKCEL® H-T heavy duty textile form of oxidized cellulose OKCEL® H-D cotton wool form of oxidized cellulose OKCEL® F cotton wool form of oxidized cellulose January 7/2018 NATURAL POLYMERS MU SCI 7 2018 28 Oxidised Cellulose – basic Description of Oxidation Process 1 January 7/2018 NATURAL POLYMERS MU SCI 7 2018 29 str 162.jpg Oxidised Cellulose – basic Schema of Oxidation Process 2 January 7/2018 NATURAL POLYMERS MU SCI 7 2018 30 img730.jpg img731.jpg Oxidised Cellulose with two to aldehydic Groups (-CH=O) in the Positions 2 and 3 is very easy to hydrolyse in the alkali Medium Diketonic Oxidised Cellulose is due to Conjugation of both Ketogroups yellow, the Water have effect on this Colour, which is dissipating. It could be caused by a reversible Hydratation. This type of the Oxidised Cellulose is also easy to hydrolyse. Cellulose haemostatic (styptic) agent January 7/2018 NATURAL POLYMERS MU SCI 7 2018 31 https://static.wixstatic.com/media/14efbf_b4f615f4d5f1ac43a6cd2d5a6c3b2070.png/v1/fill/w_130,h_157, al_c,usm_0.66_1.00_0.01/14efbf_b4f615f4d5f1ac43a6cd2d5a6c3b2070.png https://static.wixstatic.com/media/14efbf_79aebc7eaac62d82a3bd09186f7545a7.png/v1/fill/w_130,h_156, al_c,usm_0.66_1.00_0.01/14efbf_79aebc7eaac62d82a3bd09186f7545a7.png https://static.wixstatic.com/media/14efbf_06d8cc034c83d2642390ad30ec7336bd.png/v1/fill/w_130,h_156, al_c,usm_0.66_1.00_0.01/14efbf_06d8cc034c83d2642390ad30ec7336bd.png US Patent 8,828,050 B2 XStat® is a first-in-kind hemostatic device for the treatment of gunshot and shrapnel wounds. XStat works by injecting a group of small, rapidly-expanding sponges into a wound cavity using a syringe-like applicator. Each sponge contains an x-ray detectable marker. In the wound, the XSTAT sponges expand and swell to fill the wound cavity within 20 seconds of contact with blood. This creates a temporary barrier to blood flow and provides hemostatic pressure. January 7/2018 NATURAL POLYMERS MU SCI 7 2018 32 img221.jpg Podrobný popis výrobku Kompres Medicomp nester.10x10cm/100ks 4218251 Kompres z netkaného textilu Medicomp může být v mnoha oblastech na oddělení i v ambulanci vhodnou alternativou ke klasickému mulovému kompresu. Kompresy z netkaného textilu Medicomp z 60 % viskózy a 34 % polyesterových vláken mají otevřenou, mulu podobnou strukturu. Proto mají velmi dobrou savou schopnost, jsou měkké a prodyšné. Netkaný textil je čistě mechanicky stabilizován a bez pojidel i optických bělicích látek. Pro hospodárné použití jsou k dispozici kompresy z netkaného textilu Medicomp s různým počtem vrstev a s rozdílnými rozměry, sterilizované pro přímé použití i nesterilizované. Speciálně k ošetření ran s drenáží, při tracheotomiích a extenzích i jako ochrana při aplikaci kanyl a sond jsou k dispozici kompresy z netkaného textilu Medicomp Drain ve tvaru Y. Ke všeobecnému ošetření ran; jako tampon a jako kompres při ambulantních a stacionárních zásazích. January 7/2018 NATURAL POLYMERS MU SCI 7 2018 33 Cellulose Grafted by acrylic acid 001.jpg Cellulose GRAFTING to get Haemostatic (styptic) agent Cellulose GRAFTING by ACRYLIC ACID The Haemostatic (styptic) is done by influence of Ca+2 Salt of the Acrylic Acid Nitrocellulose 1 •Company SYNTHESIA Pardubice (Czech Republic) > an Example >>> •Industrial nitrocellulose type A –Nitrocellulose type A with nitrogen content 10,6-11,3% is characteristic with good solubility in alcohol-type solvents and good solubility in ethyl alcohol (up to 100 %). It forms films with Available wetting agents: ethanol, isopropanol, water – 30 or 35%. thermoplastic and good mechanical properties •Use –Explosives –Civilian – Plastics, Varnishes, Foil, …….. •Manufacture Technology –Oxidation of Wood Pulp or Cotton –HNO3 •They are ideal for wood finishing, metal, leather, coating lacquers, for production of printing inks, nail varnishes and membranes. •The manufacturing programme consists of two basic type ranges of industrial nitrocellulose, differing in their nitrogen content, viscosity, solubility in solvents and resulting nature of the film. • January 7/2018 NATURAL POLYMERS MU SCI 7 2018 34 Nitrocellulose 2 January 7/2018 NATURAL POLYMERS MU SCI 7 2018 35 •Collodium is a Solution of Nitrocelluose in ether and ethanol, having a syrup like Consistency used in Surgery as a „Liquid bandage" and for a Holding of a Covering on a given Place. Applied on the Skin, it forms the dry elastic Cellulose Film. •The ACRYLATES are currently used for this Purpose as the Spray also. • Nitrocellulose-2D-skeletal.png Nitrocellulose having high nitration Level Pyroxylin = another ENGLISH name for Nitrocellulose January 7/2018 NATURAL POLYMERS MU SCI 7 2018 36 img762.jpg img763.jpg The currently used Nitrocellulose has the Nitrogen content lower. Approx. 13,5 % w/w for the Explosive and 10,5 – 12,5 % w/w for the Civilian use. Dividing of the Nitrocellulose based on the Nitrogen content (An EXAMPLE ONLY!) Nitrocellulose Type Nitrogen content (% w/w) Mostly used Solvents Use A 10,5 – 11,2 Ethanol Celluloid, paints (Varnishes (lacquers)) M 11,2 – 11,7 Esters, ketons, mixture of diethylether - ethanol Paints (Varnishes (lacquers)) E 11,8 – 12,5 12,0 – 13,5 --- Explosives Nitrocellulose 3 •Solvent Varnishes (LACQUERS) •The lower Nitrogen Content > Solubility in EtOH and Aromatics > POLISHES •The middle Nitrogen Content > Solubility in ethylacetate & butylacetate > NITROCELLULOSE LACQUER > quick-drying >Hard layer –If a more elastic film is necessary > ELASTIC AFTER ADDITION OF PLASTICIZERS > PTHALATE PLASTICIZERS –FORMER USE WAS ALSO: •Car organic Solvent Varnishes (LACQUERS) > WATER BASED MATERIALS NOW •Ski Runner organic Solvent Varnishes (LACQUERS) January 7/2018 NATURAL POLYMERS MU SCI 7 2018 37 Nitrocellulose 4/1 - CELLULOID January 7/2018 NATURAL POLYMERS MU SCI 7 2018 38 Nitrocellulose wetted by Alcohol (100 weight Parts) s mixed in a kneading Mixer with Camphor (27 to 33 weight Parts) and the other Ingrediens (Plasticizers, Pigments, Colouring agents, Stabilizers) are added and this all is further mixed. To get good homogeneity, some Ethanol is further added. It is mixed at 40 – 50 °C for several Hours. The Filtration is the next Step. The Ethanol is evaporated during kneading at two Roll mill, at which the Homogenisation is finished. The Matter is then fully Gelantioned. The Calendered Sheets are hot pressed to a desired Thickness and after it are dried at 30 – 50 °C for several Hours to remove the Rest of the Ethanol. The last Manufacture step is a Polishing. An Advantage of the Celluloid is very good colourability, possibility of do various Graving and easy Processing. A Disadvantage is Flammability and the Manufacturing labour intensity. The freshly made Celluloid has the Camphor smell, which is lowering in the course of time. The Celluloid is soft and mouldable after heating to approx. 70 – 100 °C (Thermoforming). It is decomposed at temperatures over approx. 170 °C. Its Importance and Production volume is lowering steadily. Made of Celluloid: Combs,Table tennis Balls, Art Products etc. Nitrocellulose 4/2 - CELLULOID January 7/2018 NATURAL POLYMERS MU SCI 7 2018 39 Camphor Molekula kafru. GENERAL Systematic name 1,7,7-trimethylbicyklo[2.2.1]heptan-2-on Anglický name Camphor Summary formula C10H16O Appearance White crystalsy, aromatic smell Identification Registration number CAS 76-22-2 properties Molecular weight 152,23 g/mol Mlting point 175-177 °C Boliling temperature 204 °C Density 0,990 g/cm3 Solubility in water 1,2 mg/l Nitrocellulose 5 - ULTRAFILTRATION January 7/2018 NATURAL POLYMERS MU SCI 7 2018 40 ULTRAFILTRATIONS, so called also as MEMBRANE FILTRES, are the Micro porous films manufactured by Casting of the Nitrocellulose Solution. Their filtration Efficiency is done by the presence of the Ultrafine pores, being of 0,1 – 5,0 mm. ULTRAFILTRATIONS Cross_Flow.png ULTRAFILTRATIONS 558px-Dead-end_svg.png Pores diameter (m) Diameter range (m) Diameter mean Value (m) 0,1 – 0,3 0,25 0,3 – 0,5 0,40 0,6 – 0,9 0,85 1,0 – 1,2 1,1 2,0 – 5,0 --- An Example CELLOPHAN •Manufacturing similar to Viscose Rayon, it is from Solution, but by Casting from the flat Die to the Precipitant •Film is brittle > so it is plasticized by Glycerol (approx. 10 – 15 % w/w) •It is often surface treated by Nitrocellulose Varnish > Food Wrap and Cigarette Wrap (BOPP now) •It is mouldable after Moistening > Capping of the Glasses etc. •Water Vapour permeable after Moistening SEMIPERMEABLE MEMBRANE > HEMODIALYSIS (Formerly) • January 7/2018 NATURAL POLYMERS MU SCI 7 2018 41 January 7/2018 NATURAL POLYMERS MU SCI 7 2018 42 Xanthogenate_Cellulose_Structural_Formula_V1_svg.png CELULOSE XANTOGENATION Once more this Schema a Cellulose Content must be high, approx. 89 – 90 %w/w for the Manufacture of CELOPHANE January 7/2018 NATURAL POLYMERS MU SCI 7 2018 43 img311.jpg Acetát celulózy > vlákna, plasty Kdysi vyráběla SYNTHESIA Pardubice Nyní např. www.mazzucchelli.it > pro designové výrobky, např. brýle January 7/2018 NATURAL POLYMERS MU SCI 7 2018 44 img311.jpg Cellulose Acetate > Fibers, Plastics A Current producer e.g. www.mazzucchelli.it > for design Products, e.g. Glasses Frames January 7/2018 NATURAL POLYMERS MU SCI 7 2018 45 Cellulose based Fibres – Manufacture Schemas I img586.jpg 1) Cellulose, 2) NaOH Solution, 3) Caustic dip, 4) Pressing, 5) Fibrillation, 6) Alkalicellulose Maturing, 7) Sulfidation, 7a) CS2, 8) Dissolving Carboxymethylcellulose to VISCOSE, 9) Deaeration and Carboxymethylcellulose Maturing, 10) Spinning, 11) Filament Winding, 12) CuSO4, 13) NH3, 14) Cellulose Dissolving, 15) Filtration, 16) Tank, 17) Water, 18) Drawing Spinning, 19) Acid Liquor, 20) Washing, 21) Filament Winding VISCOSE Rayon Manufacture Cuprammonium Rayon Manufacture January 7/2018 NATURAL POLYMERS MU SCI 7 2018 46 Cellulose based Fibres – Manufacture Schema II img587.jpg 1) Acetic Acid, 2) Acetanhydride, 3) Cellulose, 4) Kneading, 5) Triacetate tank, 6) Acetone, 7) Water, 8) Precipitation, 9) Hydrolysis, 10) Dissolving of the Secondary Acetate, 11) Filtration, 12) Tank for the Spinning Solution, 13) Hot Air, 14) Spinning & Winding Cellulose Acetate Rayon Manufacture January 7/2018 NATURAL POLYMERS MU SCI 7 2018 47 Vazba molekul celulózy > sesíťovaná vlákna C:\Users\ladapospa\Documents\TECHNOLOGIE CHEMICKÝCH VLÁKEN\tabulky a grafy\img406.jpg Vazba přes –OH skupiny na jednom řetězci není žádoucí Vazba přes –OH skupiny na RŮZNÝCH ŘETĚZCÍCH JE ŽÁDOUCÍ Umělý pergamen – H2SO4 > balení tuků Vulkánfíbr – ZnCl2 > kufry, složky January 7/2018 NATURAL POLYMERS MU SCI 7 2018 48 Fibers Crosslinking – molecular Schema C:\Users\ladapospa\Documents\TECHNOLOGIE CHEMICKÝCH VLÁKEN\tabulky a grafy\img406.jpg Forming the Bond via –OH Groups on Different Chains is desirable! Artificial Parchment paper – Treatment by H2SO4 > Packaging of Fats Vulcanized fibre – Treatment by ZnCl2 > Luggage, Office letter folder Forming the Bond via –OH Groups on the same Chain is Undesirable! Microcrystalline Cellulose January 7/2018 NATURAL POLYMERS MU SCI 7 2018 49 •Inertní látka pro přenos účinné látky léčiv a potravinových doplňků •Nakypřovací prostředek v potravinách •Vláknitá přísada do potravin • Cellulose Derivatives in Pharmacy January 7/2018 NATURAL POLYMERS MU SCI 7 2018 50 img193.jpg img192.jpg Neutral and Additive Substances based on the CELLULOSE Nanocellulose January 7/2018 NATURAL POLYMERS MU SCI 7 2018 51 Nanocellulose, or microfibrillated cellulose (MFC) is a material: composed of nanosized cellulose fibrils with a high aspect ratio (length to width ratio). Typical lateral dimensions are 5–20 nanometers and longitudinal dimension is in a wide range from tens of nanometers to several micrometers. It is pseudo-plastic and exhibits the property of certain gels or fluids that are thick (viscous) under normal conditions, but flow (become thin, less viscous) over time when shaken, agitated, or otherwise stressed. This property is known as thixotropy. When the shearing forces are removed the gel regains much of its original state. The fibrils are isolated from any cellulose containing source including wood-based fibers (pulp fibers) through high-pressure, high temperature and high velocity impact homogenization (see manufacture below). Nanocellulose can also be obtained from native fibers by an acid hydrolysis, giving rise to highly crystalline and rigid nanoparticles (generally referred to as nanowhiskers) which are shorter (100s to 1000 nanometers) than the nanofibrils obtained through the homogenization route. The resulting material is known as nanocrystalline cellulose (NCC). January 7/2018 NATURAL POLYMERS MU SCI 7 2018 52 Supermolecular Structure of Cellulose I micely celulźy.jpg Space between the Microfibrils is filled by HEMICELLULOSE & LIGNIN AMORPHOUS CELLULOSE: • easy to swell • is more reactive than the crystalline one Hierarchy of STRUCTURES in CELLULOSE: • Macromolecule, • Microfibril, • Fibril, • LAMELAE. Microfibril crystalline AMORPHOUS Micellar Intermicellar REGIONS Fibrils are selectively broken in the AMORPHOUS REGIONS > CRYSTALLINE NANOPARTICLES ARE RESULTING January 7/2018 NATURAL POLYMERS MU SCI 7 2018 53 NANOCELULÓZA články 002.jpg Nanocelulóze je věnována pozornost již MINIMÁLNĚ 10 let, hlavně ve Švédsku, Finsku a Norsku January 7/2018 NATURAL POLYMERS MU SCI 7 2018 54 NANOCELULÓZA články 001.jpg Nanocellulose January 7/2018 NATURAL POLYMERS MU SCI 7 2018 55 AFM height image of carboxymethylated nanocellulose adsorbed on a silica surface. The scanned surface area is 1 μm2 > FIBRES HAVE DIAMETER approx. 80 – 100 nm Cellulose as the IONEXCHANGER January 7/2018 NATURAL POLYMERS MU SCI 7 2018 56 img933.jpg Microstructure Schema of the Cellulose Fibres based Ion exchanger Lines – Cellulose Chains, Circles - Ion exchanging Groups