Home Page,www.plastemart.com
 PRODUCT SEARCH     PROCESSORS     PRICES     PLACEMENTS      EXHIBITIONS       DISCUSSION FORUM       ARTICLES       NEWS   
Go to->Home - Technical Articles & Reports on Plastic Industry
Surface modification of fillers enhances properties and processing of filled polymers
 

Plastics often contain fillers or reinforcements to provide specific properties or reduce costs. Majority of these fillers or reinforcements are incompatible with polymer matrix. This incompatiblity results into processing as well as performance problems. The problems become more intense when the fillers/reinforcements are used at higher levels. The fillers/reinforcing materials are required to be modified on surface in order to overcome the problem of incompatibility.

Surface modification is an important step for manufacture of good quality fillers/reinforcing materials. Basically two types of surface modifications are normally used.

The first modification provides physical bond between filler and polymer. Normally waxes and fatty acids are employed in this type of physical bond. Calcium Carbonate is the largest mineral filler used particularly in PVC, the largest thermoplastics used for manufacture of filled product. Physical surface modification is less costly. The physically treated filler often command very small additional price compared to the untreated filler. However, this type of physical surface modification is not suitable for clays, wollastonites, mica or Aluminium Trihydrates.
It also is not suitable for glass reinforcements. These fillers/reinforcements need chemical bonding at molecular level.
Such a chemical surface modification is achieved by the use of "Coupling Agents" - the special chemicals containing Silanes, Titanates or Zirconates. All these chemicals are essentially organometallic in nature and contain alkoxy groups (X) that react with fillers. There is also an organo functional group (Y) that allows bonding to the polymermatrix by chemical reaction . The Y component contains different functional groups to provide bonding to different polymermatrix.

The Silanes have been in use for a very long time and are the largest coupling agents. They have been found to perform very well in polar polymers like PVC etc. as well as for thermosets and elastomers. They have limited compatibilty with Polyolefins although sometimes they are used to improve dispersion.

Titanates are more effective in Polyolefins. Titanates, however tend to discolour polymer that contain Phenols. Zirconates the most recent coupling agents overcome these limitations of Silanes/Titanates. However the use of Zirconates is still restricted on account of high cost.

The chemical bonding can also be achieved by Functionalised Polymers. These have been developed recently and are less expensive than coupling agents but are more expensive compared to physical bonding. The functionalised polymers with acid and anhydride modified PP, PE or EVA are now increasingly being used in Polyolefins, particularly for glass or mica reinforcements.

Also Read
Flame retardants for plastics are expected to grow despite regulation problems
New PP grades with better flow properties aid in cost containment of housewares
Forward this article to friend Forward this article to friend Print this article Print this article  
Back to list of articles
 
Advertise With Us    Home    Information Mart    Newsletter    Environment      Articles   Polymer Prices
About Us    Jobs in Plastic Industry    Manufacturers Plastic Industry   Products & Services Plastics  Terms Of Use
Plastic Exhibitions And Trade Fairs   Disclaimer   Software Solutions   Contact Us  Site Map
Be fan of Plastemart.com on Facebook Be Our Fan | follow Plastemart.com on Twitter Follow Us
Best viewed in IE 6.0+
Copyright © 2003 Smartech Global Solutions Ltd. All rights reserved.
Designed & Conceptualized by Plastemart - www.plastemart.com