Saturday, December 22, 2007

Polymer Chemistry Hypertext

Polymer Chemistry Hypertext provides an overview to the information included in a second semester polymer science course. The hyperlinking of the concepts allows the student to quickly obtain an overview of the concepts.

This site contains: concepts about polymer science, polymer library, and guidelines in polymer field. A example is:



Sunday, December 16, 2007

Guías y Apuntes de Ingeniería de Materiales mención Polímeros - USB

Guías y Apuntes de Ingeniería de Materiales mención Polímeros - USB

En los siguientes días se publicarán algunos archivos vinculados a las siguientes asignaturas:

MT2231: Polímeros I

Programa MT2231

MT2242: Propiedades Físicas de Polímeros I

Programa MT2242

MT2243: Propiedades Físicas Polímeros II

Programa MT2243

Bibliografía muy importante para el Curso de Propiedades,

MT3242: Caracterización de Polímeros

Programa MT3242

MC2511: Viscoelasticidad

Programa MC2511

MT3232: Polímeros II

Programa MT3232

MT2284: Laboratorio de Propiedades Físicas de los Polímeros

Programa MT2284

MC2512: Reología de Polímeros

Programa MC2512

MT2283: Laboratorio de Polímeros I

Programa MT2283

Guía Lab. I Polímeros

MT3251: Aditivos

Programa MT3251

Guía Aditivos

Agentes Nucleantes

MC2513: Tecnología del Plástico I

Programa MC2513

MC2582: Laboratorio de Tecnología del Plástico I

Programa MC2582

Guía Lab. I Tecnología del Plástico

MC2583: Laboratorio de Tecnología del Plástico II

Programa MC2583

Guía Lab. II Tecnología del Plástico

MT3283: Laboratorio de Polímeros II

Programa MT3283

MC2514: Tecnología del Plástico II

Programa MC2514

MC3127: Diseño II

Programa MC3127

Guía de Diseño II

MC2516: Elastómeros

Programa MC2516

Guía de Elastómeros

MC2515: Ingeniería de Moldes

Programa MC2515

Guía de C-MOLD y Resin Data

(guías compiladas y extraídas del portal C-MOLD Design Guide)

MC2584: Laboratorio de Tecnología del Plástico III

Programa MC2584

PROGRMAS COMPLETOS DE Ingeniería de Materiales mención Polímeros - USB

Nota: en esta sección se suministrarán archivos de ayuda y respaldo para aquellos estudiantes de esta carrera de la Universidad Simón Bolívar

Recomiendo una excelente biblioteca con libros en formato .pdf y .djvu, que es de utilidad para complementar los estudios. Lo único que deben hacer es ir a GIGAPEDIA, suscribirse y después disfrutar de la inmensa información que hay disponible gratuitamente. Otras vías son emplear programas P2P, como por ejemplo Ares Galaxy

Monday, December 10, 2007

The Glass Transition Temperature in Homologous Series of Linear Polymers

The Glass Transition Temperature in
Homologous Series of Linear Polymers
B. M. GRIEVESON*
(Polymer, Volume 1, 1960, Pages 499-512)


Members of three homologous series of linear aliphatic polyesters were synthesized and their glass transition temperatures are reported. The theory of glass transition temperatures in random copolymers is applied to polymers in homologous series by treating them ag copolymers of the first member of the series with polymethylene. It is shown that each methylene group added to a polymer to Jorm the next member of the series makes a constant specific contribution to the glass transition temperature lust as does the addition of each homopotymer unit in a random copolymer. There is a discrepancy between the observed and predicted values of the contribution made by each methylene group.

INTRODUCTION

A KNOWLEDGE of the relationship between the chemical structure and glass transition temperature (Tg) of polymers is an important aid in the search for materials with specific physical properties in a given temperature range. The effect of changing chemical structure in homologous series of polymers has been studied by many workers. Interest has been mainly concentrated on locating glass transition temperatures, although some quantitative measurements of specific volume-temperature relationships in the region of Tg have been made (1, 2). The results of these investigations have shown that the insertion of new chemical units into a polymer chain leads to a change in the glass transition temperature. The direction and amount of the change can be predicted qualitatively from a knowledge of the steric nature of the inserted unit and its effect on the configuration of the polymer and the interaction between polymer chains. From studies of glass transition temperatures in random copolyrners, Gordon and Taylor (3), Mandelkern and co-workers (1), and Wood (4) have shown that each homopolymer makes a specific partial contribution to the glass transition temperature in proportion to its own Tg and its weight fraction in the copolymer. If the quantitative relationship developed for random copolymers is applied to the insertion of a new chemical unit into a homopolymer, it should be possible to predict the resultant change in glass transition temperature.

Three homologous series of linear aliphatic polyesters have been prepared together with some random and block copolyesters and polyester m
elt blends. The glass transition temperatures of these polymers have been measured, and these results together with those for homologous series studied by other workers are examined in the light of the theory of glass transition temperatures in random copolymers.

EXPERIMENTAL

Preparation of polyesters

The polyesters were prepared by condensation of dibasic acids with equimolar proportions of a glycol at 200°C in a stream of oxygen-free nitrogen. In order to obtain polymers of the requisite number-average molecular weight (greater than 10,000), in a reasonable time, it was necessary to reduce the pressure in the reactor to 1 mmHg when the polymer molecular weight reached 5,000. Condensation was continued until the number-average molecular weight reached at least 10,000.

The oxalate, malonate and n-alkylmalonate polyesters were prepared from the diethyl esters of the corresponding acids since the acids themselves are unstable at the reaction temperature. The diethyl esters were heated at 150°C with equimolar proportions of the glycol until the theoretical amount of ethyl alcohol was almost completely distilled out of the reaction mixture. The temperature was then raised to 200°C and the polycondensation completed under reduced pressure. Polymers of the desired molecular weight were obtained with relative ease in some systems, but when necessary 0.01 per cent of anhydrous zinc acetate was added as a condensation catalyst.

The diethylene succinate-sebaeate random copolymers were prepared from a mixture of succinic acid and sebacic acid in the required proportions, together with an equimolar amount of diethylene glycol, by the same condensation technique as described above.

The block copolymers were prepared from poly(diethylene succinate) and poly(diethylene sebacate), both of approximately 2,000 number-average molecular weight. These low molecular weight polyesters were mixed inthe required proportions with an equimolar amount of hexamethylene di-isocyanate (H.M.D.I.) and allowed to react at 60°C to give a block copolymer having a molecular weight of approximately 20,000. Although this method of block copolymer formation involves the introduction of urethane linkages into the polyester chain, it has the advantage that it canbe performed at relatively low temperatures. At elevated temperatures, ester interchange occurs easily and would result in a disordering of the units of the two blocks, thus producing a random copolymer. The introduction of urethane linkages into the polyesters will result in changes from the Tg of the pure polymers. H.M.D.I. was chosen as the linking agent because, although it is less reactive than the aromatic di-isocyanates, its structure is much more similar to that of the linear aliphatic polyesters. It should, therefore, cause smaller deviations from the true Tg of the polyesters. For purposes of comparison, high molecular weight homopolymers of diethylene succinate and diethylene sebacate were also prepared by chain-extending polyesters of molecular weight 2,000 with H.M.D.I.

Molecular weight measurements

Number-average molecular weights were estimated by end-group analysis. The hydroxyl end-groups were measured by acetylation with pyridine/acetie anhydride reagent and the carboxyl end-groups were titrated with 0.1 N alcoholic potash. The reproducibility of the molecular weight measurements (about +/- 5 per cent at mol. wt. 2,000) became poorer at higher molecular weights, but the accuracy was sufficient to allow a molecular weight versus glass transition temperature relationship to be established for poly(diethylene adipate), Figure 1. After this relationship was obtained, molecular weight

measurements were only used to follow the polyesterification and to check that all the polyesters prepared had a molecular weight above 10,000.

Measurements of glass transition temperature

A penetrometer technique similar to that described by Edgar and Ellery (5) was used to make a preliminary approximate estimate of Tg for each polyester. A fiat-ended needle was fixed in the bottom of a vertical brass spindle which was mounted in a rigid frame so as to move freely in a vertical direction. The spindle was loaded to give a pressure of 400 g/mm^2 at the needle point. A dial gauge (reading to 0.0005 in.) was mounted in the frame to measure the vertical movement of the spindle. The polymer sample in a small tray 1 in. in diameter and 0.3 in. deep was gently heated to about 30°C above its melting point and then damped in the penetrometer frame below the needle point. The polymer and the lower part of the apparatus were immersed in n-hexane which had been cooled to -100°C and the penetrometer needle was lowered onto the polymer surface. The temperature of the hexane hath was raised by about 1°C per minute and readings of the dial gauge were taken at 2 min intervals. Figure 2 shows a typical penetrometer curve. The intersection of the tangents to the two arms of the curve gave a reproducible temperature Tb (the penetrometric brittle poin0 which generally lay about 5°C above the dilatometric glass transition temperature Tg (see Table 2). With all of the polyesters studied, smooth penetrometer curves like Figure 2 were obtained. This finding differs from that of Edgar (6) who found that with poly(ethylene terephthalate) an abrupt change occurred in the slope of the penetrometer curve at the temperature at which the dilatometric Tg was observed.

REFERENCES

1 MANDELKERN, L., MARTIN, G. M. and QUINN, F. A., J. Res. nat. Bur. Stand., 1957, 58, 137

2 ROGERS, S. S. and
MANDELKERN, L., J. Phys. Chem., 1957, 61, 985

3 GORDON, M. and TAYLOR, J. S., J. Appl. Chem., 1952, 2, 493

4 WOOD, L. A., J. Polym. Sci., 1958, 28, 319

5 EDGAR, O. and ELLERY, E., J. Chem. Soc., 1952, p. 2633

6 EDGAR, O., J. Chem. Soc., 1952, p. 2638

...This paper will continue...

Saturday, November 24, 2007

EINSTEIN'S ANNUS MIRABILIS 1905

THE HIGH RESOLUTION NMR SPECTROSCOPY OF POLYMERS

THE HIGH RESOLUTION NMR SPECTROSCOPY OF POLYMERS

F. A. Bovey

Bell Telephone Laboratories, Incorporated, Murray Hill, New Jersey 07974

(Progress in Polymer Science, Volume 3, 1971, Pages 1-108)

Nuclear magnetic resonance (NMR) spectroscopy has proved to be of great significance in many aspects of polymer science. Because of the rapid expansion of this field, a review is felt to be justified at this time even though a number have appeared in recent years. (1-6) Earlier NMR studies have dealt with solid polymers, and the spectra obtained have been of the so-called "wide-line" type. In such spectra, as in the corresponding spectra of non-polymeric solids, analysis of the resonance lines, particularly if known as a function of temperature, can give information about the packing and motion of the polymer chains. (7-9) To such studies have more recently been added the measurement of the spin-lattice and spin-spin nuclear relaxation times, T1 and T2 (see below), in both solid state and solution, providing further insight into the motion and interaction of polymer chains. (10-21)

The present review will deal primarily with the structure and conformation of vinyl polymers, and will therefore (for reasons to be made clear in the next section) be confined to spectra of polymer solutions, since in general features providing such information cannot be resolved in solid state spectra.

The study of biopolymers has been a particularly active field of high resolution NMR spectroscopy very recently. Because of space limitations and because this area clearly deserves a review of its own, it will not be treated here.

REFERENCES

  1. F.A. BOVEY and G. V. D. TIERS, Fortschr. Hochpolyrn. 3, 139 (1963).

  1. D. W. MCCALL and W. P. SLICHTER, in Newer Methods of Polymer Characterization (B. KE, Ed.), Wiley-lnterscience, New York (1964).

  1. F. A. BOVEY, article entitled Nuclear Magnetic Resonance, in Encyclopedia of Polymer Science and Technology, Vol. 16, Wiley-Interscience, New York (1968).

  1. K. C. RAMEY andW. S. BREY,JR.,J. MacromoL Sci. C 1,263 (1967).

  1. H. A. WILLIS and M. E. A. CUDBY, Applied Spectroscopy Reviews 1, 2,237 (1968).

  1. J. C. WOODBREY in Vol. 3 of The Stereochemisto, ofMacromolecules (A. D. KETLEY, Ed.), Marcel Dekker, New York (1968).

  1. W. P. SLICHTER, Fortschr. Hochpolym. Forsch. 1, 35 (1958).

  1. J. G. POWLES, Polymer 1, 219 (1960).

  1. J. A. SAUER and A. E. WOODWARD, Rev. Mod. Phys. 32, 88 (1960).

  1. A.W. NOLLE and J. J. BILLINGS, J. Chem. Phys. 30, 84(1959).

  1. J. G. POWLES and K. LUSZCZYNSKI, Physica 25, 455 (1959).

  1. J. G. POWLES, A. HARTLAND and J. A. E. KAIL. J. Polymer Sci. 55, 361 (1961).

  1. E. G. KONTOS and W. P. SLICHTER, J. Polymer Sci. 61, 61 (1962).

  1. W. P. SLICHTER and D. D. DAvis, J. Appl. Phys. 34, 98 (1963).

  1. W. P. SLICHTER and D. D. DAVIS, J. Appl. Phys. 35, 3103 (1964).

  1. W. MCCALL and E. W. ANDERSON, Polymer4, 93 (1963).

  1. J. G. POWLES, J. H. STRANGE and D. J. SANDIFORD, Polymer 4, 401 (1963).

  1. J. G. POWLES, B. 1. HUNT and D. J. SANDIEORD, Polymer 5, 585 (1964).

  1. W. P. SLICHTER, J. PolymerSci. C 14.33 (1966).

  1. D. W. MCCALL, D. C. DOUGLASS and D. R. FALCONE, J. Phys. Chem. 71, 998 (1967).

  1. W. P. SLICHTER and D. D. DAVIS, Macromolecules 1, 47 (1968).

Tuesday, October 23, 2007

GUERY

Version English
Guery manufacturers of bakery equipment, pastry moulds, pastry bags, flexible silicon moulds, bread pans, elevator buckets, ducting for aspiration, ventilation, dust removal, silos.

Version French

Fabricant de matériel Boulangerie-Pâtisserie, moules à pâtisserie, poches à pâtisserie, moules souples silicone, plaques à pain, godets d’élévateur, ...

Saturday, October 20, 2007

Second International Symposium on Polyvinylchloride, Lyon-Villeurbanne, France, 5-9 July 1976

Pure and Applied Chemistry

Vol. 49, Issue 5


Second International Symposium on Polyvinylchloride (PVC), Lyon-Villeurbanne, France, 5-9 July 1976

Chemical modification of PVC
T. Suzuki
p. 539 [full text - pdf 1212 kB]

Characterisation of poly(vinylchloride)
M. E. Carrega
p. 569 [full text - pdf 741 kB]

The rheology of PVC - An overview
E. A. Collins
p. 581 [full text - pdf 503 kB]

Polyvinyl chloride - Processing and structure
G. Menges and N. Berndtsen
p. 597 [full text - pdf 913 kB]

Rupture fragile des produits en PVC rigide
R. Jacob
p. 615 [full text - pdf 374 kB]

The stabilization of PVC against heat and light
H. O. Wirth and H. Andreas
p. 627 [full text - pdf 715 kB]

Combustion of PVC
M. M. O'Mara
p. 649 [full text - pdf 574 kB]


Friday, October 19, 2007

Nanomechanics Lab

Nanomechanics Lab
Center of Biotechnology, TU Dresden

How does a cell work, mechanically? How do the individual components, molecules and proteins work to fulfill their cellular function?

Nanomechanics Lab

Sunday, September 30, 2007

Relation Between Flow Properties, Molecular Mass and Branching of Polymer

Text taken from:

Vinogradov, Georgii Vladimirovich; Malkin, Aleksandr Yakovievich. Rheology of Polymers: Viscoelasticity and Flow of Polymers. Mir Publishers. Moscow; 1980. p. 153-154

---------


Relation Between Flow Properties, Molecular Mass and Branching of Polymer

Introduction

While considering the temperature dependence of the viscosity of linear polymers, we introduced the concept of the macromolecular segment as a molecular-kinetic unit performing elementary acts of translation in space from one equilibrium state to another. if the size of the segment is much smaller than that of the macromolecule, these transfers --the elementary acts of flow --are independent of molecular mass. However, for the macromolecule to be transferred irreversibly, it is necessary that the centre of gravity of the entire molecule be shifted as a result of the displacement of its constituent segments. But the higher the molecular mass of the polymer, i. e., the greater the number of segments in the macromolecule, the larger is the number of cooperative segment motions that must be effected for its centre of gravity to be shifted and the higher must be the viscosity.

Study of the effect of molecular mass on the flow properties of polymers is supposed to provide answers to a number of questions. How doe molecular mass affect the initial viscosity and non-Newtonian flow behavior (anomalous viscosity) of polymer? How can one compare the flow properties of polymers with the different structures of the macromolecular chain, considering that at one and the same molecular mass the chain length and flexibility may strongly differ for polymers of different nature? How does the molecular mass distribution affect the dependence of the Newtonian (initial) viscosity on molecular mass and how does the non-Newtonian flow behavior change? In evaluating the effect of molecular-mass distribution (MMD) on the flow properties of polymers there also arises the most important question: What characteristics of MMD and what values of molecular mass of polydisperse polymers about be used to compare the flow properties of various polymer?

…to be continued

Saturday, September 15, 2007

Molecular Structure of Nucleic Acids: A Structure For Deoxyribose Nucleic Acid

Molecular Structure of Nucleic Acids: A Structure For Deoxyribose Nucleic Acid

See: Nature 171, 737 (1953)
(Watson and Crick: DNA)DNA

Sunday, September 02, 2007

Polymer Journal: ACS Publications

Macromolecules

Vol. 40, Issue 14 July 10, 2007 Cover

On the cover: The artwork aims on describing various tools allowing the nanoscale analysis of functional polymer blends as applied for the photoactive layer of polymer solar cells. In detail, the background represents the 3D volume reconstruction of the bulk heterojunction blend MDMO-PPV/PCBM as obtained by TEM tomography (only the PCBM domains are visualized). Top left: the TEM bright-field images show the PCBM domains imbedded in the MDMO-PPV matrix. Bottom left: the AFM images show demixing of PCBM from MDMO-PPV with annealing time. Top right: the AFM tip symbolizes conductivity-AFM measurements allowing local conductivity measurements of the photoactive layer with few nanometer lateral resolution and the corresponding IV characteristics of such C-AFM measurements. See: Yang, X.; Loos, J. Macromolecules 2007, 40, 1353-1362.

Biomacromolecules

Biomacromolecules explores the interactions of macromolecules with biological systems and their environments as well as biological approaches to the design of polymeric materials. Cutting-edge research at the interface of polymer science and biological sciences.

REVIEWS ON ADVANCED MATERIALS SCIENCE
Papers on-line and free about materials science

Acta Chimica Slovenica
Acta Chimica Slovenica (ACSi) provides a forum for the publication of original and significant work in the chemical and closely related areas of research. Reviews, scientific and technical articles, and short communications are welcome.

Crystal Research and Technology
Journal for Experimental and Industrial Crystallography

Journal of Zhejiang University SCIENCE

Wednesday, June 20, 2007

Do You Need a Polymer Handbook?

If you answer is YES:

click here to download:

PART 1: mihd.net



PART 2: mihd.net



PART 3: mihd.net



PART 4: mihd.net



PART 5: mihd.net

Password: tF





I recommend this site: Very and Very Important Site

How to get this Polymer HandBook
Step One:










Step Two:












Polymer Data Handbook: On-line access


Friday, June 08, 2007

Word of the Day








Quote of the Day








Article of the Day








This Day in History








Today's Birthday








In the News





Wednesday, May 23, 2007

INFRARED EXAMINATION OF POLYMER

Taken From: J. Haslam, H.A. Willis, D.C. Squirrel, Identification and Analysis of Plastics, Iliffe, London, 1972. p. 368, 369, 385,386

INFRARED EXAMINATION OF POLYMER

Polythene

When examined as thin films (0.001 to 0.002 in or 0.025 to 0.05 mm thickness) all kinds of polythene appear very similar in their spectra. The strong absorption bands at 3.4 μm (2941 cm-1), 3.8 μm (2632 cm-1), 7.3 μm (1370 cm-1) and 13.8 μm (725 cm-1) all arise from --CH2-- chain. When the infrared spectrum of a resin shows these features, and no others of significance , it may be presumed to be polythene, but there is naturally a strong similarity between the spectrum of polythene and the spectrum of high molecular weight linear aliphatic hydrocarbons, including paraffin wax.

There is usually no difficulty in deciding, from its physical properties whether a substance is polythene or paraffin wax, since the latter is soluble in ether polythene is substantially insoluble. This test is useful when dealing form example with wax-coated paper: both polythene and paraffin wax are removed by boiling toluene, but only the latter is ether soluble.

Polypropylene

The spectrum of isotatic polypropylene is somewhat surprising, since, in addition to the bands normally attributable to --CH2-- and –CH3 groups at 3.4 μm y near 7 μm, a number of sharp bands of medium intensity occur in the 8 μm to 12 μm region.

In the spectrum of molten isotactic polypropylene, which is presumably amorphous, and so-called atactic polypropylene which is amorphous at room temperature all the prominent structure between 8 μm and 12μm disappears, except for bands at 8.7 μm and 10.3 μm. The only important difference in the spectra of the molten polymer and atactic polymer is the band in the latter at 11.3 μm. This is thought to be due to the chain-terminating group R·C·(CH3)=CH2 and its prominence in this spectrum of the atactic resin is presumably due to the relatively low molecular weight of the sample examined.

It is reasonable to presume therefore that the additional bands which appear in the spectrum of the isotactic resin are not due directly to the chemical structure of the resin. Nor are they due to the interaction of molecules when packed together in the crystal, since different crystalline forms of polypropylene in which the molecules are packed in different ways, have virtually identical spectra. It is therefore concluded that the features of the spectrum of isotactic polypropylene are due to the helical arrangement of the chain of the individual polymer molecule.

Unsaturation in polypropylene

Examination of polypropylene as comparative thick specimens (≈ 0.015 in or 0.4 mm thickness) reveals a shoulder (which varies in intensity in different specimens) at approx. 11.25 μm (889 cm-1) on the side of the polypropylene band at 11.1 μm (901 cm-1). This shoulder, which is characteristic of pendant methylene unsaturation, arises from the end group on the polypropylene chain:


Thursday, May 17, 2007

Espectroscopia Infrarroja (IR) dispersiva y Espectroscopia Infrarroja de Transformada de Fourier (FTIR)

GUERY SAENZ

Carnet: 02-35425

Tarea # 2 de MT-3242

1. Espectroscopia Infrarroja (IR) dispersiva [1]

El espectrómetro infrarrojo de doble rayo está constituido por las siguientes partes:

  1. Una fuente de radiación, la cual es producida por medio del calentamiento eléctrico de un filamento de Nernst (óxidos de circonio, torio y cerio) (7100-1000 cm-1) o un Globar (carburo de silicio) (5500-600 cm-1) a 1000-1800 ºC. La radiación infrarroja de la fuente es adicionalmente dividida en dos rayos y enfocados en la muestra por un sistema de espejos.
  2. Un área del muestreo que permite la comodidad para una amplia variedad de accesorios (células). El rayo de referencia y de muestra pasan a través de la célula de referencia y la célula de muestra.
  3. Un sistema fotómetro-óptico de lectura. Para medir la absorción de una muestra, deben ser comparadas las intensidades del rayo de muestra y referencia. El rayo de referencia y de muestra pasan a través del atenuador y de la rejilla, respectivamente, y son reflejadas por un sistema de espejos al espejo rotativo, el cual refleja o transmite alternativamente, los rayos del monocromador. Los dos rayos luego caen sobre el detector (termocupla) y son amplificadas. Si las intensidades son idénticas, el amplificador no tiene salida. Cualquier diferencia en las intensidades resultará en una señal de salida de la frecuencia del dispositivo. Esta señal de desequilibrio es adicionalmente amplificada y usada para conducir al atenuador dentro o fuera del rayo de referencia en respuesta a la señal creada al detector por el rayo de muestra. La posición del atenuador es una medida de la absorción relativa de la muestra; al transmitir su posición al dispositivo digital la absorción es indicada.
  4. Un sistema de registro de datos. La relación de las intensidades del rayo de referencia y de muestra (I0/I) es alimentado a la unidad de registro, la cual representa la transmitancía versus el numero de onda en una escala lineal.

Los espectrómetros están disponibles para rangos desde 4000 a 600 cm-1 (e incluso hasta 200 cm-1)

2. Espectroscopia Infrarroja de Transformada de Fourier (FTIR) [1]

Espectroscopia Infrarroja de Transformada de Fourier, es una técnica que emplea un interferómetro (en lugar de un monocromador), por ejemplo: un interferómetro de Michelson. El interferómetro consiste en dos espejos dispuestos en ángulo recto uno respecto del otro y un divisor de rayo a 45º de los espejos. Un espejo está fijado en una posición estacionaria y el otro puede ser desplazado en una dirección perpendicular a su superficie frontal a una velocidad constante.

El dispositivo que divide el rayo permite obtener de la luz proveniente de la fuente luminosa, que un 50% de ésta sea transmitida y el otro 50% sea reflejada. Consiste de una delgada película que recubre la superficie de un material de actividad óptica. Un segundo recubrimiento de igual espesor de este material de apoyo (denominado compensador) es ubicado en uno de los brazos del interferómetro para igualar las longitudes de las trayectorias ópticas en ambos brazos.

Si la radiación de entrada es monocromática, la señal del detector (o interferograma) va a través de una serie de máximos (los dos rayos de luz estarán en fase cuando retornen al divisor) y mínimos (los dos rayos de luz estarán fuera de fase cuando ellos retornen al divisor). Si el espejo es desplazado continuamente la señal oscilará desde un máximo a un mínimo durante cada movimiento de un cuarto de longitud de onda del espejo.

Si la radiación es policromática, la señal del detector o interferograma está compuesta de la señal resultante para cada frecuencia presente en una radiación de entrada. Cada una de las frecuencias de entrada pueden ser tratadas independientemente, y por consiguiente; la salida será la suma de todas las oscilaciones del coseno causadas por todas las frecuencias ópticas en la radiación policromática de entrada.

El interferograma también contiene información sobre la intensidad de cada frecuencia en el espectro.

La información de salida del detector es digitalizada en un computador y transformada al Dominio de Fourier –cada frecuencia individual es filtrada del interferograma complejo. Luego las señales son convertidas en un espectro infrarrojo convencional.

Espectroscopia Infrarroja de Transformada de Fourier es usada en:

i. Detección de señales débiles.

ii. Estudios sobre muestras a muy bajas concentraciones (0,5% concentración; 20 µg muestra).

iii. Estudios sobre monocapas absorbidas (por ejemplo: una traza de tinta sobre un papel).

iv. Estudios de espectros de un cristal único (por ejemplo: un cristal de benceno de 300 µm de diámetro).

v. Estudios en soluciones acuosas en la región entre 950 y 1550 cm-1.

vi. Análisis de vibraciones.

vii. Estudio de bandas infrarrojas sensibles a cambios de conformación.

3. Preparación de las muestras para la evaluación IR [1]

3.1. Polímeros sólidos

Técnicas de tabletas comprimidas en KBr: el polímero en la forma de pequeñas partículas es dispersa en una tableta de bromuro de potasio. Las tabletas de KBr, son preparadas al moler la muestra de polímero (2mg) con KBr (100-200 mg) y comprimido todo en una tableta transparente. El KBr debe ser completamente deshidratado al secar a 105 ºC.

Preparación de gránulos de KBr a partir de micromuestras: muchas micromuestras originadas a partir de separaciones de cromatografía de capa fina (CCF). La muestra es separada por CCF, el adsorbente es removido del área del cromatograma que contiene el material separado, la muestra es lavada con un solvente adecuado, filtrada para remover el adsorbente, y finalmente mezclada con KBr.

Empleando un triangulo poroso de KBr comprimido y encapsulado (elementos Wick-Stick) en un pequeño frasco de vidrio, con la finalidad de que la evaporación sea restringida al centro del frasco de KBr (ello se puede ser realizado en un paso único), el adsorbente que contiene la muestra es retirado de la placa de CCF y transferido al frasco de vidrio que contiene un Wick-Stick empleando un embudo de base delgada.

La técnica de liofilización: en este método el polímero molido (alrededor de 200 mg) es ubicado en un pequeño frasco que contiene al menos 2 g de KBr en 5 ml de agua. El frasco es conectado con un aparato de enfriamiento especial. Diferentes frascos con varias muestras pueden ser ubicadas en el aparato simultáneamente. Las soluciones en el frasco son luego enfriadas hasta el punto congelamiento y aplicado vacío. El hielo sublimado es recolectado en un condensador lleno con CO2 sólido. Después de 6h las muestras son completamente deshidratadas y el polímero es perfectamente recubierto con KBr. La muestra es molida en un mortero y luego es preparada la muestra.

La técnica de suspensión: el polímero en la forma de pequeñas partículas es disperso en una gota de líquido de suspensión como parafina líquida (nujol) o hexaclorobutadieno, o bien aceite de cloroflorocarbono (aceite de Kel-K). La suspensión es luego ubicada entre dos placas para formar una capa de 0,1 a 0,01 µm de espesor.

4. Aspectos prácticos [2]

Modernos instrumentos del FTIR tienen un número de ventajas sobre el IR, incluyendo mejores relaciones de la señal/ruido y la capacidad de registrar espectros completos en escalas de tiempo mucho más pequeñas (típicamente segundos en lugar de minutos). Así al usar el espectrómetro FTIR, es posible realizar mediciones resueltas en el tiempo tal como monitorear rápidas reacciones; con instrumentación más especializada es posible examinar la dinámica molecular en escalas de tiempo menores a un segundo.


5. Referencias Bibliográficas

[1] Rabek, J. F. Experimental Methods in Polymer Chemistry: Physical Principles and Applications. John Wiley & Sons. 1980. p. 223-224, 249-251

[2] Young, R. J. Novell, P. A., Introduction to Polymers. Chapman & Hall. 2da Edición, Londres (1991). p. 226-227


Sunday, May 06, 2007

Installing: Pro/ENGINEER 2001 and C-MOLD 2000

Instalacion de Pro/ENGINEER 2001

1. Averigua tu HOSTID: haz click en el boton INICIO, luego en el recuadro ejecutar escribe cmd. Se abrirá una ventana en MS-DOS, en ella coloca ipconfig/all. Finalmente copia tu HOSTID. (como hacerlo)

(Imagen tomada de http://www.trucoswindows.com)

2. Abre el archivo PTC.dat, primero ejecuta el bloc de notas y del menu archivo abre PTC.dat, luego cambia los 4 HOSTID=00-00-00-00-00-00 por el HOSTID de tu computadora.
Es necesario que cuando te dispongas a realizar la instalacion, poseas de una conexion a internet.
3. Borra el archivo license.
4. Arranca el keygen y guarda en un lugar seguro la licencia que se creo.
5. Ejecuta el archivo proe (6.682 Kb) y selecciona instalación típica (TYPICAL) o la completa (COMPLETE), después que sea requerido indica la direccion en la cual se guardo el archivo license, es decir en el cuadro Specify License Serve--Locked License File (No Server Running)--License File Path---Ubica el directorio donde se guardo el archivo License.

Consejo: Si vas a instalar PROE-2001 en tu computadora portatil, ubica la direccion HOSTDID de la tarjeta inalambrica (WIRELESS), asi no tendras inconvenientes.

Instalacion de C-MOLD 2000

Versión Corta:
1. Debes tener una tarjeta de de Red ethernet y el protocolo de red TCP/IP.
2. Instala c-mold pero no lo ejecutes.
3. Obtén el nº de identificación del sistema ejecutando IDRED2 que se encuentra en el directorio CRACK.
4. En la carpeta CRACK ejecuta cmold2001lic.exe.
5. Oprime el botón "Add" y pega el número que quedó en memoria en el paso 3.
6. Sigue los pasos 8 al 13 de la versión larga.

Versión Larga:
1. Debes tener una tarjeta de de Red ethernet y el protocolo de red TCP/IP.
2. Instala c-mold pero no lo ejecutes.
3. Obtén el nº de identificación del sistema ejecutando:
"/bin/cmoldlmd.exe -sysid"
4. Se ve en pantalla por ejemplo:
C-MOLD system ID = 0x92d64e05 (2463518213)
5. Cópia el valor alfanumérico despues de 0x (en este ejemplo: 92d64e05).
6. En la carpeta crack ejecuta:
cmold20001lic.exe
7. Oprime el botón "Add" y escribe el número que copiaste en 4 (en este ejemplo: 92d64e05).
8. Oprime el botón "Ok". Aparecerá de nuevo la ventana inicial.
9. Oprime el botón "Select Features" en el recuadro que aparece ve seleccionando cada módulo y lo añades con el botón ">".
10. Una vez que finalices oprime el botón "Ok". El cuadro desaparace.
11. Oprime el botón generar, esto crea la licencia en el directorio del crack.
12. Copia la licencia en el directorio donde se instaló C-mold (ejemplo: C:\C-MOLD\Advanced Solutions20001).
13. Puedes trabajar con c-mold

Note:

An ethernet network card is required since the C-MOLD License Manager uses the hardware ethernet address. The TCP/IP network protocol must be installed.

To obtain System ID run /bin/cmoldlmd.exe -sysid, then add number to the System ID's list. Example of cmoldlmd.exe output:

C-MOLD system ID = 0x92d64e05 (2463518213)

You should add 92d64e05 as System ID.

Be careful adding ID's, you cannot enter more than number of IP aliases for you machine. If you have only one IP address, then you can enter only one System ID, if you have two IP addresses, you can enter two System ID's, and so on, up to four addresses. If you wrong with it, C-MOLD license manager will not run.

About the features: all of the features have names, except the one: "keyofmon", I noticed that when u including ONLY this feature, C-MOLD doesnt check anything and seems to work fine!!! I have no time to test it, so it's up to you.


Nota: si tienes algunas sugerencias para mejorar estas indicaciones, escribe a guery.saenz@gmail.com

Physical Properties of Polymer. MT2242 & MT2243

Archives about Physical Properties Of Polymers I and II
(Propiedades físicas de los polímeros I y II)
MT-2242 y MT-2243

Hiemenz's Book to Physical Properties Of Polymers I and II
Instructions to Open
Step One and Step Two to Get Hiemenz's Book
Link to Amazing Book



Thursday, May 03, 2007

Biopolymer's Videos

Injection molding of biopolymer-based composites

Producing biopolymer-wood fibre test specimens with a Battenfeld injection molder HM 60/210


Bioplastic




BIOP

BIODEGRADEABLE POLYMERS

This section is dedicated to biodegradable polymers:

Biomedical Polymer

Note: Depending on you this site improves and increases its files. If you have polymer documents and papers, share them with me. Come on! Write me an e-mail: guery.saenz@gmail.com

Saturday, April 28, 2007

Nota Muy Importante

Por motivos ajenos a mi voluuntad, he tenido problemas con el portal que me suministrada el espacio para almacenar la informacion que se encuentra en este blog. Por este inconveniente, no será posible, por ahora, descargar ningún tipo de artículo o publicación referida en cada entrada.
Con la mayor prontitud resolveré el inconveniente para poder compartir los archivos que dispongo.

Por otra parte, mi cuenta en Google Adsense fue cancelada, es decir ya no dispondré en este portal de la publicidad suministrada por Google.


Guery Saenz.
Estudiante de Ingeniería de Materiales mención polímeros de la Universidad Simón Bolívar