Dépouillements

Keeping an eye on quality / G Saunders in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 192, N° 4451 (04/2002)

[article]  inPOLYMERS PAINT COLOUR JOURNAL - PPCJ > Vol. 192, N° 4451 (04/2002) . - p. 15-16 Titre : Keeping an eye on quality Type de document : texte imprimé Auteurs : G Saunders, Auteur ; E Meehan, Auteur Année de publication : 2002 Article en page(s) : p. 15-16 Langues : Anglais (eng) Catégories : Chimie analytique Chromatographie sur gel Logiciels Poids moléculaires Polymères -- Analyse Index. décimale : 667.9 Revêtements et enduits Résumé : Gel permeation chromatography (GPC) is used to determine the molecular weight distributions of polymers. The authors discuss the benefits of accompanying analysis software. Today's polymeric materials require rigorous quality control (QC) testing to ensure the batch-to-batch quality of products is consistently maintained. Molecular weight distribution must also be carefully determined. Even the smallest of changes in the molecular weight distribution of a polymer can lead to huge changes in physical properties, such as mechanical strength, melt viscosity and polymer processability. Note de contenu : - Key tool - Data traceability - Monitoring variations - Data archiving - Desirable degradation - Valuable results Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28091 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
000326	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Measuring in microns / Henry Warson in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 192, N° 4451 (04/2002)

[article]  inPOLYMERS PAINT COLOUR JOURNAL - PPCJ > Vol. 192, N° 4451 (04/2002) . - p. 17-19 Titre : Measuring in microns Type de document : texte imprimé Auteurs : Henry Warson, Auteur Année de publication : 2002 Article en page(s) : p. 17-19 Langues : Anglais (eng) Catégories : Latex Mesure Mesure -- Instruments Taille des particules Index. décimale : 667.9 Revêtements et enduits Résumé : The author details just a few of the methods and instruments available that are able to measure the size of fine particles down to 0.003 micrometers in diameter. The methods of measuring fine particle sizes have seen major developments in the past few decades. This applies to fine solids, but especially to latex particules. The oldest method for separating solid particles by size was the use of a sieve. Later, a range of sieves with different meshes was used. Woven sieves are available for measuring sizes of particles from several millimeters to 20 micrometers, although some care is needed in the latter case to ensure that the sieve does not become distortes. Shape has a strong influence on particule size by sieving. Originally, the only method of measuring the size of latex particles was by direct microscopic observation, which could give a maximum magnification of about 400. The phase microscope with oil immersion increases magnification to a maximum of about 600. The latex is diluted at least 10 times before a drop is placed on a slide and a cover glass is pressed over it. The assumption here is that particles in latex are essentially spherical, but this is noy always true. Simple observations can show whether particles in any latex are unisized or have a variety of sizes and shapes. In dealing with solids, size and shape have more significances. The minimum size which can be observed directly is about 0.4 micrometers. Note de contenu : - Modern methods - Electrode method - Light scattering - Photo correlation spectroscopy - Fine solids measurement - Turbimetry - Disc centrifuge - FIGURES : 1a. Flow schematics of Horiba system - 1b. Operation of Horiba system - 2. Accusizer 780 particle sizing system - 3. Brookhaven instrument, showing the effects of spinning - Equation 1. The stokes equation, which relates the sedimentation of particles to size and viscosity Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28092 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
000326	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Finding the right cure / Stephen Davidson in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 192, N° 4451 (04/2002)

[article]  inPOLYMERS PAINT COLOUR JOURNAL - PPCJ > Vol. 192, N° 4451 (04/2002) . - p. 24-26 Titre : Finding the right cure Type de document : texte imprimé Auteurs : Stephen Davidson, Auteur Année de publication : 2002 Article en page(s) : p. 24-26 Langues : Anglais (eng) Catégories : Bois -- Revêtements Dispersions et suspensions Inhibiteurs (chimie) Oxygène Peinture -- Recyclage Polymères cationiques Revêtements -- Séchage sous rayonnement Revêtements -- Séchage sous rayonnement:Peinture -- Séchage sous rayonnement Revêtements poudre:Peinture poudre Technologie médicale Index. décimale : 667.9 Revêtements et enduits Résumé : Radiation curing equipment is beginning to enjoy a period of development. The author looks at what strides are being taken. One of the most important demands made by users of radiation curing is the availability and reliability of equipment. The area of aquipment includes issues of running costs and ease of introduction or retro-fitting to existing coating lines. A great step forward in electron beam curing has been the introduction of more affordable equipement, which runs at a lower accelerating voltage than earlier commercial e.b.units (J Chrusciel, Proceedings RadTech Europe Basel, 2001, 367-373). Equipment that has a lower accelerating voltage tends to benefit from greater reliability. this is because of the longer life of both the metal foil windows and the electrongun filaments. The extent to which electrons will penetrate coatings is related to the accelerating voltage and the thickness of the coating. Penetration of thick coatings is achievable with quite modest voltages (for a 25 mm thick coating only 110 kVolts is required). Because e.b. curing is carried out under a nitrogen blanket, oxygen inhibition is not a problem, and for radical curing processes an initiator does not have to be used. As a result, the cure occurs at ambient or slightly higher temperatures (dependent upon the thickness of the coating and the thermal conductivity of the substrate). The lack of a photoinitiator in a formulation means that the cured formulations do not contain migratable species originating from the this source. Note de contenu : - Packaging issues - Oxygen inhibition - Wood coatings - Aqueous dispersions - Powder coatings - Cationically curable materials - Medical applications - Recycling technologies Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28093 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
000326	-	Périodique	Bibliothèque principale	Documentaires	Disponible