Hi dear all,
Is there any way to reduce the MFI for Epdm/pp blends with Phenolic Resin? It is desired to be operated in extrusion yet, the material has high flow rates so we would like to alternate it while keeping mechanical properties as it is.
So far, the additive level adjustment seems to be the most common answer.
Thanks in advance,
I do not agree with Ismail. "MFI reduce" refers to increase in melt viscosity. The answer would be reactive compounding to facilitate more chemical interactions between polymer chains or using branched polyolefins to increase the number (or density) of physical entanglements. Plasticizers will definitely increase the MFI value.
Your system is a typical TPV formulation. You should think about creating chain restrictions in PP phase and improving interactions between PP-g-MA and other components if it is used in the formulation.
Good luck.
Mostly, TPVs have been used in injection molding applications. So, the high melt flow rate is necessary for the process's ability to increase productivity. By contrast, low viscosity can be improved by finding out new raw materials (PP high MFI. e.g. 60 g/10 min and low viscosity of EPDM). Possibly, adding internal and external lubricants with adequate content (migration of additives have to be concerned).
Dear Mustafa, you need to perform a dynamic silane cross-linking:
1) first step: grafting an alkenyl-substituted alkoxysilane/peroxide agent to a heterophasic polyolefin composition : you need to compound vinyl-trimethoxysilane (VTMS) or methacryloylpropyl-trimethoxysilane (VMMS) in an amout of 5% ( or ranging from 2% to 7% depending to the X-linking density to obtain) then you need to add a peroxide to the EPR tp X-link the silane to the Polyolefin matrix, for example: 1,1'-bis (tert-butylperoxy)-diisopropylbenzene or dicumyl peroxide or n-butyl-4,4'-bis-(tert-butylperoxy)-valerate or 2,5 di(tert butylperoxy)2,5-dimethylhexane. The peroxide has to be added from 0.1% to 0.8% by weight, try with 0,5%. Compound the ingredients with an extruder or a lab mixer (Brabender).
2nd Step: process comprises curing the silane-grafted cross-linkable thermoplastic elastomer : Cross-linking is obtained by contacting the composition with hot water preferably at a temperature above 50°C (60-70°C) ) for few days ( 1-4 ) or moisture in a steam heated room ( Relative Humidity > 80% ) for some days ( 5-10 ) after shaping., or in a standard atmosphere with 30-70% of Relative Humidity for some weeks ( 2 -5 ). See atachet patent about WO2007147687 . All the best.
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