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C A T A L Y S T
Through this column ET will cover briefly
relevant information on key components that
goes into an extruder
1. Melt flow index
It is also called melt index or melt flow rate
The number of grams of polymer that can be pushed out of a
capillary die of standard dimensions (diameter: 2.095 mm, length:
8.0 mm) under the action of standard weight (2.16 kg for PE, at
190°C) in 10 minutes (ASTM Standard 1238). The usual melt index
range is from less than 1.0 (called fractional) to more than 25 (up to
100 for injection molding). For PP it is usually called melt flow rate
and the standard temperature is 230°C.
2. Linear Polymers
It is also classified as branched polymers.
In linear polymers, the monomeric units are linked together, linearly,
with little or no long chain branching. In branched polymers, side
chains are attached to the backbone of the molecular chain. High-
density polyethylene (HDPE) is linear, while low-density polyethyl-
ene (LDPE) is branched. Linear LDPE (LLDPE) is “stiffer” than LDPE in
shear but “softer” in extension. In extension the LLDPE chains slide
by without getting entangled (since the chain branches are very
short).
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ET enables recapitulating few definitions
and terms with respect to extruders and
compounds
EXCERPTS
Peter Drucker
the first and famous ‘Management Guru’ is no more. But
his thoughts on leadership and management live forever. Here’s recalling
some of his gems:
• ‘Tasks of management are: Fulfilling the institution’s specific purpose,
making work productive and the worker achieving, and managing social
impact and social responsibilities’.
• ‘Efficiency is the minimum condition of success; effectiveness is its
foundation’
• ‘Human resource management should make the strengths of employees
productive and their weaknesses irrelevant’
• ‘Management is the means by which a society makes productive its own
values and beliefs’
• ‘Work without high quality is dishonesty’
• ‘The basic factor in economic development is the rate of brain formation’
From Moses to Einstein
In a speech he gave at the London School of Economics at its centennial
function, the late K. R. Narayanan (former President of India) spoke of the
contribution of Jews to LSE and the world. Here is an extract from this
delightful speech: “First there was Moses who looked up to the skies and
said that everything came from the heavens. Then came Solomon, who
looked further down and declared that everything came from the head, that
is Wisdom. He was followed by Jesus who looked further down and said that
everything came from the heart. Next was Karl Marx who decreed that
everything came from the stomach. Then came Sigmund Freud who looked
a little further down and asserted that everything came from sex. And finally
up popped Albert Einstein who was certain that everything was relative.”
JANUARY-FEBRUARY 2006
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VOL .01 / ISSUE-01
Long Bi-lobed Conveying Element with Short lead
This Long Bi-lobed Normal Conveying Element is a short lead
element. The profile of the element is called the Erdmenger profile
(E) or the Normal (N) profile. The ratio of the lead to diameter is 0.5.
In general, elements with lead to diameter ratios of 0.5-0.8 are used
for building up pressure prior to the die-head or for increasing the
fill the channels prior to mixing, and for squeezing prior to melting
in the case of Crystalline or Semi-Crystalline polymers. These
elements are no longer used in the melting zone of amorphous
polymer due to excessive wear. The length of this element is twice
as long as the lead of the element.
Eccentric Tri-lobed Conveying Elements
This Eccentric Tri-lobed Conveying Element is also referred to as a
Camel back element. It has been used in the metering zone of
Thermoset material.
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