KHW : Blooming Problems in Rubber Products: Why? How to Avoid?

KnowHow Webinar: Blooming Problems in Rubber Products: Why? How to Avoid?
Speaker: Dr. Hans-Joachim Graf
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Blooming, Bleeding are terms for the same phenomenon. Ingredients migrating to the surface and either crystallize or building an oily layer on the surface of rubber. Both phenomena give reason to customer concerns, if not claims. In case of crystallization rubber surface turns grey to pale white. Sometime there is Iridescence underneath the crystalline layer. This layer under the crystalles stays liquid due to a melting point suppression. The color is created by light fraction. There are no chromophores involved. Migration to the surface of the rubber happens due to a lack of solubility or compatibility, because rubber below glass transition temperature – even after vulcanization – behaves more like a liquid. We observe temperature dependent migration and separation In this Webinar we will demonstrate the reason behind Blooming and Bleeding. We will go through all family of ingredients either in none polar or in polar rubbers. We will show effects in processing, even we might not see any bloom or bleed. We will discuss examples, how to obtain data of solubility limits in a practicable way without sophisticated equipment. Even the solubility delta paramter can be easily measured with little effort. The participant should be able to judge ingredients in his formula regarding the danger of blooming or bleeding. He should be able to take measures to avoid this phenomena.
Speaker – Dr.
Hans-Joachim Graf : Hans-Joachim Graf: brings about 40 years experience in the rubber processing industry both as a material and as a process developer. After completing his doctorate at the Macromolecular Institute of the University of Freiburg, he gained his experience primarily in the production of technical articles, in the chemical as well as in the machinery industry. He has published over 60 technical articles and has participated in more than 15 patents. He has held seminars and lectures at the DIK, as well as at the University of Waterloo, Canada. He was honored with the “Erich Konrad” Medal of the German Rubber Society (DKG) 2012. Since 2009 he has been working as a consultant in various companies of the rubber industry as well as a scientific consultant and partner of the TechnoBiz Group.
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