Hi I am investigating the use of TPE in a dairy farming environment - specifically with exposure to cow dung/urine, aside from the potential for chemical attack is there any risk of biological attack? We are specifically concerned with loss of mechanical properties. Could anyone point me towards some resources that IO might use to investigate this or if anyone has any info or direct experience of using TPE in animal waste I would appreciate your insights.
Comment by Composite Agency on 04 Mar 2011 at 12:21:29
Is there any indication of what sort of TPE is used or is of preferential use? By biological attack, do you mean fugitive emissions of e.g. NH3? This depends on a lot of physical-chemical parameters, which requires quite specific insight in the application, processing, etc.
You can be quite sure that the TPE loses mechanical properties in the presence of the urine. How much exactly depends on many factors. I cannot give you any bootstrap indication because the analysis is complex, for example read this (from another recent forum post):
"I found that dry Polyamide 6 has an E modulus of 3.1 GPa, with 3 wt% Water E becomes 1.1 GPa, and with 6 wt% Water it decreases to 0.7 GPa.".
So in presence of a relative strong solvent, 80% reduction is not impossible. We developed CheFEM code to deal with this, also check the CheFEM section.
Hope this helps, Composite Agency
Comment by billy murphy on 04 Mar 2011 at 14:05:35
Hi, Thanks for your reply.
No sorry I don't mean NH3, that is chemical attack and not biological. Apologies I should have made my post clearer, I meant bacteria or bugs. I am aware that most long chain polymers are actually very resistant to bacteria, hence the issue with making polymers biodegradable, but I was wondering if anyone had specific experience of biological attack/resistance of TPE's.
By the way: SEBS Polypropylene and TPE's are typically unaffected by water. (although there are some TPE's that are designed to interact with water Distropols DRYFLEX comes to mind).