EP0953555A1 - Procédé de préparation de particules de propergols et explosifs fusibles - Google Patents

Procédé de préparation de particules de propergols et explosifs fusibles Download PDF

Info

Publication number
EP0953555A1
EP0953555A1 EP99105812A EP99105812A EP0953555A1 EP 0953555 A1 EP0953555 A1 EP 0953555A1 EP 99105812 A EP99105812 A EP 99105812A EP 99105812 A EP99105812 A EP 99105812A EP 0953555 A1 EP0953555 A1 EP 0953555A1
Authority
EP
European Patent Office
Prior art keywords
matrix liquid
emulsion
melt
particles
adn
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP99105812A
Other languages
German (de)
English (en)
Other versions
EP0953555B1 (fr
Inventor
Ulrich Dipl.-Ing. Teipel
Horst Dr. Krause
Karlfred Leisinger
Thomas Heintz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Original Assignee
Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV filed Critical Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Publication of EP0953555A1 publication Critical patent/EP0953555A1/fr
Application granted granted Critical
Publication of EP0953555B1 publication Critical patent/EP0953555B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
    • C06B21/0033—Shaping the mixture
    • C06B21/0066—Shaping the mixture by granulation, e.g. flaking
    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
    • C06B21/0033—Shaping the mixture
    • C06B21/005—By a process involving melting at least part of the ingredients
    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B31/00—Compositions containing an inorganic nitrogen-oxygen salt

Definitions

  • the invention relates to a method for producing essentially spherical particles of meltable, moisture-sensitive fuels and explosives and oxidizers, especially ammonium dinitramide (ADN).
  • ADN ammonium dinitramide
  • Ammonium dinitramide is an oxidizer for fuels and of great importance as an explosive. In the application are for both manufacturing and processing compactible particles desired. In the Manufacture of conventional crystalline fuels and explosives but usually arise very irregular Particle. This applies in particular to ADN.
  • the crystalline substance mostly with heating in one or dissolved in several suitable solvents and by defined cooling, the substance crystallizes out. This process can be carried out several times if necessary become. Due to the differences in solubility between Substance and impurities become unwanted accompanying substances severed because they're either a priori remain unsolved, or because if they are also in Solution because of their low concentration the matrix liquid remain when the crystals has already failed.
  • Inoculation of supersaturated solutions is also known or hypothermic melting, with traces of Solid substance in the form of germs that prevent the formation of solid phase can be added.
  • GB 2 187 726 A describes a process for the production a solid explosive mixture, so-called emulsion explosives, being a discontinuous phase in the form an oxidizer salt heated and melted and in one continuous phase serving as fuel, e.g. Paraffin oil or wax, is emulsified.
  • the emulsion additives such as emulsifiers or crystallization nuclei, added to a finely dispersed to get discontinuous phase and a confluence to prevent the disperse drops.
  • the emulsion is cooled, whereby an explosive mixture is obtained in which the oxidizer salts are finely dispersed are a spontaneous detonation, as in coarsely dispersed Prevent particles from occurring.
  • the invention has for its object a method for the production of uniform, in particular spherical Particles more meltable, more sensitive to moisture
  • ADN Ammonium dinitramide
  • the propellant or Explosive or the oxidizer converted into a melt and combined with a matrix liquid in the substance to be recrystallized is difficult or impossible is soluble.
  • the matrix liquid ensures that the moisture-sensitive fuels and explosives and oxidizers, such as the particularly hygroscopic ADN, no water during recrystallization, e.g. Humidity. It is chosen so that the molten substance can be emulsified. The later one The phase mixture is separated solely on the basis of the different melting points of the starting material and matrix fluid and not due to changes in concentration a solution.
  • the focus is to make available the melt in the matrix liquid preferably less than 50% by mass and in particular less than 60 % By mass.
  • the matrix liquid after crystallization is separated, can be reused and for example be carried out in a cycle.
  • the melt can be in the fuel or explosive or additives soluble in the oxidizer are mixed with those regarding the later product quality of the ADN particles Stability, sensitivity or fluidity can be improved.
  • a matrix liquid primarily oils, e.g. Paraffin oil or silicone oil, in Question, which have a hydrophobic character.
  • oils e.g. Paraffin oil or silicone oil, in Question, which have a hydrophobic character.
  • spherical Particles with defined particle properties, e.g. average particle size, particle size distribution, specific Preserve surface. The spherical particles not only lead to an optimal bulk and knock density, but also to a high energy density and favorable combustion behavior.
  • the emulsion is produced by introducing Energy into the fluid system. This can be done by shaking, Stirring, by introducing vibrations into the system, e.g. by means of ultrasound or by injecting the Melt into the matrix liquid or vice versa.
  • Emulsifiers and stabilizers can interfacial tension between both components and the viscosity the outer phase, and thus the manufacturing conditions and affects the stability of the emulsion become.
  • an emulsion of hygroscopic ADN in hydrophobic matrix liquid also hydrophobic emulsifier, e.g. Silicon dioxide, added the stability of the emulsion is increased and the coalescence at which the emulsified droplets flow together to form a continuous phase, reduced. Consequently, by adding a such emulsifier under otherwise the same boundary conditions an emulsion of finer droplets can be achieved. Conversely, if a stabilizer is added, otherwise the same boundary conditions are larger droplets of emulsified substance.
  • the ADN droplets as a disperse phase and one Matrix liquid existing and above the melting point emulsion tempered by ADN is in the third step of the inventive method below the melting point of Cooled down ADN, so that the disperse ADN drops to solid crystallize particles.
  • the crystallization process can, in addition to the use of a specially for the Crystallization required temperature gradients, both by entering mechanical energy, as well can be controlled by adding crystallization nuclei.
  • the entry of mechanical energy during crystallization to produce the finest possible crystalline product can be done using a stirrer or ultrasound the concentration of the disperse phase can be controlled can.
  • the inventive method can be both continuous as well as carried out in batches.
  • a discontinuous process variant in which the manufacture the emulsion and the crystallization of the disperse Drops can be carried out in a reactor e.g. various stirrers, such as blade or propeller stirrers, or discontinuous gear rim disperser for Preparation of the emulsion.
  • a reactor e.g. various stirrers, such as blade or propeller stirrers, or discontinuous gear rim disperser for Preparation of the emulsion.
  • With input of stirring energy the emulsion is then cooled, so that spherical Crystallize particles.
  • the two process steps of emulsification and recrystallization can also be carried out separately in terms of time and location be, the emulsion after its preparation is conveyed into a second reactor in which the Recrystallization, e.g. through a suitable temperature gradient, can be influenced in a targeted manner.
  • the emulsion initially using colloid mills, static mixers or continuous gear rim dispersion machines and then into the crystallization zone, e.g. in a tubular reactor or cascade crystallizer.
  • a separation unit for separating the recrystallized particles from the matrix liquid provided, the separation by sedimentation, Filtration or centrifugation can be done. After this The particles are separated with a suitable one Washed solvent and dried.
  • ADN crystalline ammonium dinitramide
  • the grain is jagged and angular. Grain size and grain shape vary widely.
  • 2 and 3 show with the inventive method from a paraffin emulsion manufactured spherical particles of ammonium dinitramide (ADN) with an average grain diameter below 500 ⁇ m in two different magnifications. The grain is almost exactly spherical and that Grain spectrum is relatively narrow.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Medicinal Preparation (AREA)
  • Colloid Chemistry (AREA)
  • Silicon Compounds (AREA)
EP19990105812 1998-04-16 1999-03-23 Procédé de préparation de particules de propergols et explosifs fusibles Expired - Lifetime EP0953555B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19816853 1998-04-16
DE1998116853 DE19816853A1 (de) 1998-04-16 1998-04-16 Verfahren zur Herstellung von Partikeln schmelzfähiger Treib- und Explosivstoffe

Publications (2)

Publication Number Publication Date
EP0953555A1 true EP0953555A1 (fr) 1999-11-03
EP0953555B1 EP0953555B1 (fr) 2005-09-21

Family

ID=7864703

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19990105812 Expired - Lifetime EP0953555B1 (fr) 1998-04-16 1999-03-23 Procédé de préparation de particules de propergols et explosifs fusibles

Country Status (3)

Country Link
EP (1) EP0953555B1 (fr)
DE (2) DE19816853A1 (fr)
NO (1) NO312954B1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2884244A1 (fr) * 2005-04-12 2006-10-13 Snpe Materiaux Energetiques Sa Obtention de cristaux de dinitroamidure d'ammonium (adn); cristaux d'adn et les composites energetiques en contenant.
WO2019229385A1 (fr) * 2018-05-30 2019-12-05 Arianegroup Sas Procede d'obtention de cristaux de dinitroamidure d'ammonium (adn); cristaux d'adn et les composites energetiques en contenant
DE102020122328B3 (de) 2020-08-26 2021-08-12 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung eingetragener Verein Verfahren zur Herstellung von Partikeln aus Ammoniumdinitramid (ADN)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10201937B4 (de) * 2002-01-19 2005-08-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zur Herstellung von mit Additiven versetztem Ammoniumdinitramid (ADN)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2887723A (en) * 1955-02-23 1959-05-26 Stamicarbon Process for granulating material
US3468986A (en) * 1966-11-15 1969-09-23 David J Watanabe Method for producing a solid particulate material
US3522334A (en) * 1961-05-09 1970-07-28 Exxon Research Engineering Co Preparation of spherical solid oxidizer pellets from nitronium perchlorate-lithium perchlorate mixture
DE1467203A1 (de) * 1964-09-09 1972-01-27 Bundesrep Deutschland Verfahren zur Herstellung von kugeligem,nicht backendem Ammoniumnitrat mit einer mittleren Korngroesse von etwa 10 bis 300 mu
US4118797A (en) * 1977-10-25 1978-10-03 Energy And Minerals Research Co. Ultrasonic emulsifier and method
DE2924029A1 (de) * 1978-06-13 1979-12-20 Montedison Spa Verfahren zur herstellung von sphaeroidisch geformten, bei raumtemperatur festen produkten
US5071635A (en) * 1988-02-18 1991-12-10 Mitsubishi Materials Corporation Method of preparing ceramic microspheres
WO1993016415A1 (fr) * 1992-02-14 1993-08-19 Research Laboratories Of Australia Pty. Ltd. Particules spheroïdales utiles en electrostatographie
EP0759324A2 (fr) * 1995-08-18 1997-02-26 Rohm And Haas Company Un produit perlé formé à base d'eau
WO1997047571A1 (fr) * 1996-06-11 1997-12-18 United Technologies Corporation Procede de preparation de particules spheriques de composes energetiques

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2187726B (en) * 1986-03-14 1989-11-15 Ici Plc Solid explosive composition.

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2887723A (en) * 1955-02-23 1959-05-26 Stamicarbon Process for granulating material
US3522334A (en) * 1961-05-09 1970-07-28 Exxon Research Engineering Co Preparation of spherical solid oxidizer pellets from nitronium perchlorate-lithium perchlorate mixture
DE1467203A1 (de) * 1964-09-09 1972-01-27 Bundesrep Deutschland Verfahren zur Herstellung von kugeligem,nicht backendem Ammoniumnitrat mit einer mittleren Korngroesse von etwa 10 bis 300 mu
US3468986A (en) * 1966-11-15 1969-09-23 David J Watanabe Method for producing a solid particulate material
US4118797A (en) * 1977-10-25 1978-10-03 Energy And Minerals Research Co. Ultrasonic emulsifier and method
DE2924029A1 (de) * 1978-06-13 1979-12-20 Montedison Spa Verfahren zur herstellung von sphaeroidisch geformten, bei raumtemperatur festen produkten
US5071635A (en) * 1988-02-18 1991-12-10 Mitsubishi Materials Corporation Method of preparing ceramic microspheres
WO1993016415A1 (fr) * 1992-02-14 1993-08-19 Research Laboratories Of Australia Pty. Ltd. Particules spheroïdales utiles en electrostatographie
EP0759324A2 (fr) * 1995-08-18 1997-02-26 Rohm And Haas Company Un produit perlé formé à base d'eau
WO1997047571A1 (fr) * 1996-06-11 1997-12-18 United Technologies Corporation Procede de preparation de particules spheriques de composes energetiques

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2884244A1 (fr) * 2005-04-12 2006-10-13 Snpe Materiaux Energetiques Sa Obtention de cristaux de dinitroamidure d'ammonium (adn); cristaux d'adn et les composites energetiques en contenant.
WO2006108991A2 (fr) * 2005-04-12 2006-10-19 Snpe Materiaux Energetiques Obtention de cristaux de dinitroamidure d'ammonium (adn) ; cristaux d'adn et les composites energetiques en contenant
WO2006108991A3 (fr) * 2005-04-12 2007-03-22 Snpe Materiaux Energetiques Obtention de cristaux de dinitroamidure d'ammonium (adn) ; cristaux d'adn et les composites energetiques en contenant
US7789980B2 (en) 2005-04-12 2010-09-07 Snpe Materiaux Energetiques Preparation of ammonium dinitroamide (ADN) crystals, ADN crystals and energetic composites containing them
WO2019229385A1 (fr) * 2018-05-30 2019-12-05 Arianegroup Sas Procede d'obtention de cristaux de dinitroamidure d'ammonium (adn); cristaux d'adn et les composites energetiques en contenant
FR3081864A1 (fr) * 2018-05-30 2019-12-06 Arianegroup Sas Obtention de cristaux de dinitroamidure d'ammmonium (adn) ; cristaux d'adn et les composites energetiques en contenant
DE102020122328B3 (de) 2020-08-26 2021-08-12 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung eingetragener Verein Verfahren zur Herstellung von Partikeln aus Ammoniumdinitramid (ADN)

Also Published As

Publication number Publication date
NO991178L (no) 1999-10-18
EP0953555B1 (fr) 2005-09-21
DE59912567D1 (de) 2006-02-02
NO991178D0 (no) 1999-03-10
DE19816853A1 (de) 1999-10-21
NO312954B1 (no) 2002-07-22

Similar Documents

Publication Publication Date Title
EP0399266B1 (fr) Préparaton de dispersiones sphérique par cristallisation d'émulsiones
EP1044712B1 (fr) Agent antimousse pour milieux aqueux
EP0046927A1 (fr) Procédé de production de dispersions et matériaux photographiques
DE69104879T2 (de) Oberflächenaktives Mittel für in situ erzeugte Glasblasen enthaltender Emulsionssprengstoff.
DE3786115T2 (de) Gegossene sprengstoffzusammensetzung und verfahren.
DE102006025187B4 (de) Verfahren zur Herstellung von wenig stoßempfindlichen Sprengstoffpartikeln
DE2449529C3 (de) Verfahren zur Herstellung von Komplexverbindungen aus 4,4'-Methylendianilin und Alkalisalzen in Form einer feinteiligen Dispersion
EP0953555A1 (fr) Procédé de préparation de particules de propergols et explosifs fusibles
EP1256558A2 (fr) Procédé de production de cristaux à partir de propergols, explosifs et agents oxydants en solution dans un solvant
DE60130900T2 (de) Verfahren zur fällung fein verteilter feststoffpartikel
DE102004002318A1 (de) Verfahren zur Herstellung feindisperser kristallinger Treib-, Explosivstoffe und Oxidatoren
DE102004004964B4 (de) Verfahren zur Herstellung von Komposit-Partikeln aus kristallinen Explosivstoffen und deren Verwendung
DE10201937B4 (de) Verfahren zur Herstellung von mit Additiven versetztem Ammoniumdinitramid (ADN)
DE10149814B4 (de) Verfahren zur Herstellung von Kristallen aus in Lösungsmitteln gelösten Feststoffen
DE2521235A1 (de) Verfahren zum transport wachsartiger rohoele
EP1090894A1 (fr) Procédé de fabrication de fines particules d'explosifs
DE2308154C3 (de) Gießbare Sprengstoffmischungen auf der Basis von Hexogen, Oktogen und Trinitroluol sowie ihre Herstellungs- und Verarbeitungsverfahren
CA2183009A1 (fr) Methode de desemulsification
EP0562391A1 (fr) Procédé pour le traitement et/ou la fabrication d'une émulsion, en particulier une émulsion de graisse
DE970394C (de) Verfahren zur Herstellung von Margarine
EP0014439A2 (fr) Procédé de séparation de mélanges de matières grasses en composants à points de fusion différents
EP1297756A1 (fr) Compositions de stérols sphériques, leurs préparation et utilisation
DE3014160A1 (de) Kristallisationsverfahren
DE10152396A1 (de) Herstellung wasserfreier Nitrocellulose und Eyplosivstoffe in sphäroider Form
EP1055652A1 (fr) Procédé de fabrication de fines particules d'explosifs

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): CH DE ES FR GB LI NL SE

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWAN

17P Request for examination filed

Effective date: 20000422

AKX Designation fees paid

Free format text: CH DE ES FR GB LI NL SE

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DERANGEWAND

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DERANGEWAND

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

RBV Designated contracting states (corrected)

Designated state(s): CH DE ES FR GB LI NL SE

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): CH DE ES FR GB LI NL SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20050921

Ref country code: GB

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20050921

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REF Corresponds to:

Ref document number: 59912567

Country of ref document: DE

Date of ref document: 20051027

Kind code of ref document: P

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20051221

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20060101

REF Corresponds to:

Ref document number: 59912567

Country of ref document: DE

Date of ref document: 20060202

Kind code of ref document: P

NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060331

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060331

GBV Gb: ep patent (uk) treated as always having been void in accordance with gb section 77(7)/1977 [no translation filed]

Effective date: 20050921

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20060622

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20061020

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

EN Fr: translation not filed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20050921

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20180322

Year of fee payment: 20

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 59912567

Country of ref document: DE