handbook of polypropylene and polypropylene composites, revised and expanded (plastics engineering)

HANDBOOK
OF
POLYPROPY1ENE
AND
POLYPROPYLENE
COMPOSITES
Second
Edition,
Revised
and
Expanded
edited
by
Harutun
G.
Karian
RheTech,
Inc.
Whitmore
Lake,
Michigan,
U.S.A.
MARCEL
MARCEL
DEKKER,
INC.
NEW
YORK
• BASEL
Copyright © 2003 by Marcel Dekker, Inc.

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Copyright © 2003 by Marcel Dekker, Inc.
PREFACE
Since the publication of the first edition of this handbook in March 1999, there

have been significant changes in the manufacture of polypropylene resin with
the consolidation of many companies in order to better utilize raw material
and technology resources: BP (BP þAmoco), Basell (BASF þ Shell þ
Montell), ExxonMobil Chemical Company (Exxon þ Mobil) and Chevron
Phillips (Chevron þ Phillips) Chemical Company. Most recently, Dow Chemical
Company is striving to be a majo r producer of polypropylene resin. In addition,
Dow has acquired Union Carbide business that includes impact modifier
technology. Similarly, Cr ompton Corporation includes Uniroyal and Aristech
for the manufacture of maleated polypropylene used as chemical coupling agent
in glass fiber reinforced polypropylene.
With the rapid growth of TPO applications, the automotive industry is
pushing for cost effective replacement of polycarbonate, ABS and PPO=PS into
molded parts having molded-in-color and scratch-mar resistant characteristics.
Likewise there are join t ventures in order to meet marketing demands, e.g.
GM-Basell to develop nanocomposites in polypropylene resin.
Copyright © 2003 by Marcel Dekker, Inc.
Associated with increased interest in utilizing polypropylene technology,
the first edition of the Handbook has been well received worldwide. Con se-
quently, I have been asked by Russell Dekker to be Editor for a revised and
expanded second edition. This request provides an opportunity to include more
information concerning options to make polypropylene composites that better suit
marketing requirements. A number of modifications have been made to several
existing chapters (1, 3, 6, 7 and 8) of the first edition, along with the addition of
six new chapters (15–20) to the second edition of the Handbook.
In Chapter 1, global trends of polypropylene usage are described in light of
recent economic slow-down. The development of specialty products is one area
of increased activity.
Chapter 3 includes new data regarding reinforcement of polypropylene
using a new grade of OCF glass fiber. Wood filled highly crystalline polypropy-
lene using chemically coupled polypropylene is described as having enhanced

mechanical properties. A key addition to Chapter 3 summarizes recent develop-
ment of nanocom posites using exfoliated clay treated with maleated polypropy-
lene.
Chapter 6 has been rewritten to provide new insights into experimental
techniques in impact testing to better characterize anticipated end-use impact
behavior of polypropylene based materials.
Chapter 7 is updated to include new metallocene technology with the
growth of TPO appli cations to meet increasing end product demands.
Chapter 8 has been expanded to include recent developments in surface
modification of talc to replace PVC and engineering thermoplastics by talc filled
materials with molded in color. The section on surface modifiers for talc filler
includes description of a new grade of talc called R-Talc that improves scratch
resistance and impact properties of TPO composites. Zero Force technology is
cited as a recent break-through in talc manufacture to effectively compact fine
grades of talc into easy to feed granules for enhanced processability via
compounding extrusion.
Chapter 15 describes recent advancements in surface treatment of mica to
suit hybridization with glass fiber reinforcement. This combination yields
composites with enhanced mechanical properties and minimum warpage of
mold parts.
Chapter 16 provides up-to-date technology of high purity submicrometer
talc filler with lamellar microstructure. By compacting the fine talc grade into
densified granules for ease of processability, enhancement of mechanical proper-
ties are practically attained for polypropylene composites.
Chapter 17 describes automotive applications for polypropylene and poly-
propylene composites with the utilization of new technology, e.g. exfoliated clay
nanocomposites.
Copyright © 2003 by Marcel Dekker, Inc.
The utilization of wollastonite fibers to reinforce polypropylene is given in
Chapter 18. This avenue to interphase design has particular merit; since it features

inherent mar-scratch resistance combined with mechanical properties attributed to
high aspect ratio fibers.
Chapter 19 provides fundamental descri ption of mold shrinkage behavior
for polypropylene composites. Shrinkage is described as a combined function of
material characteristics, process conditions for injection molding, and mold
design parameters. Hence, notions of single valued shrinkage are replaced by a
range of values depending on the operating window for a given molded product
design.
Finally, Chapter 20 provides an update on developments of nanocomposite
concentrates to enhance the compounding of materials with enhanced mechanical
and thermal properties.
Harutun G. Karian
Copyright © 2003 by Marcel Dekker, Inc.
CONTENTS
Preface
1. Global Trends for Polypropylene
Michael J. Balow
2. Polypropylene: Structure, Properties, Manufacturing Processes,
and Applications
William J. Kissel, James H. Han, and Jeffrey A. Meyer
3. Chemical Coupling Agents for Filled and Grafted
Polypropylene Composites
Darilyn Roberts and Robert C. Constable
4. Stabilization of Flame-Retarded Polypropylene
Robert E. Lee, Donald Hallenbeck, and Jane Likens
5. Recycling of Polypropylene and Its Blends: Economic and
Technology Aspects
Akin A. Adewole and Michael D. Wolkowicz
Copyright © 2003 by Marcel Dekker, Inc.
6. Impact Behavior of Polypropylene, Its Blends and Composites

Josef Jancar
7. Metallocene Plastomers as Polypropylene Impact Modifiers
Thomas C. Yu and Donald K. Metzler
8. Talc in Polypropylene
Richard J. Clark and William P. Steen
9. Glass Fiber-Reinforced Polypropylene
Philip F. Chu
10. Functionalization and Compounding of Polypropylene
Using Twin-Screw Extruders
Thomas F. Bash and Harutun G. Karian
11. Engineered Interphases in Polypropylene Composites
Josef Jancar
12. Mega-Coupled Polypropylene Composites of Glass Fibers
Harutun G. Karian
13. Characterization of Long-Term Creep-Fatigue Behavior for
Glass Fiber-Reinforced Polypropylene
Les E. Campbell
14. Mica Reinforcement of Polypropylene
Levy A. Canova
15. Use of Coupled Mica Systems to Enhance Properties of
Polypropylene Composites
Joseph Antonacci
16. Performance of Lamellar High-Purity Submicrometer an d
Compacted Talc Products in Polypropylene Compounds
Wilhelm Schober and Giovanni Canalini
17. Automotive Applications for Polypropylene and Polypropylene
Composites
Brett Flowers
Copyright © 2003 by Marcel Dekker, Inc.
18. Wollastonite-Reinforced Polypropylene

Roland Beck, Dick Columbo, and Gary Phillips
19. Part Shrinkage Behavior of Polypropylene Resins and
Polypropylene Composites
Harutun G. Karian
20. Polypropylene Nanocomposite
Guoqiang Qian and Tie Lan
Copyright © 2003 by Marcel Dekker, Inc.
CONTRIBUTORS
Akin A. Adewole Basell USA, Inc., Elkton, Maryland, U.S.A.
Joseph Antonacci Suzorite Mica Products Inc., Boucherville, Quebec, Canada
Michael J. Balow Basell Polyolefins USA, Inc., Lansing, Michigan, U.S.A.
Thomas F. Bash Ametek Westchester Plastics, Nesquehoning, Pennsylvania,
U.S.A.
Roland Beck Nyco Sales, Calgary, Alberta, Canada
Les E. Campbell Owens Corning Fiberglas, Anderson, South Carolina,
U.S.A.
Giovanni Canalini Superlab S.r.l., Italy
Levy A. Canova Franklin Industrial Minerals, Kings Mountain, North Caro-
lina, U.S.A.
Copyright © 2003 by Marcel Dekker, Inc.
Philip F. Chu Saint-Gobain Vetrotex America, Wichita Falls, Texas, U.S.A.
Richard J. Clark Luzenac America, Englewood, Colorado, U.S.A.
Dick Columbo Nyco Sales, Calgary, Alberta, Canada
Robert C. Constable BRG Townsend, Mt. Olive, New Jersey, U.S.A.
Brett Flowers General Motors Corporation, Pontiac, Michigan, U.S.A.
Donald Hallenbeck Great Lakes Chemical Corporation, West Lafayette,
Indiana, U.S.A.
James H. Han BP Amoco Polymers, Inc., Alpharetta, Georgia, U.S.A.
Josef Jancar Technical University Brno, Purkynova, Brno, Cze ch Republic
Harutun G. Karian RheTech, Inc., Whitmore Lake, Michigan, U.S.A.

William J. Kissel BP Amoco Polymers, Inc., Alpharetta, Georgia, U.S.A.
Tie Lan Nanocor, Inc., Arlington Heights , Illinois, U.S.A.
Robert E. Lee Great Lakes Chemical Corporation, West Lafayette, Indiana,
U.S.A.
Jane Likens Great Lakes Chemical Corporation, West Lafayette, Indiana,
U.S.A.
Donald K. Metzler ExxonMobil Chemical Company, Houston, Texas, U.S.A.
Jeffrey A. Meyer BP Amoco Corporation, Naperville, Illinois, U.S.A.
Gary Philips Nyco Sales, Calgary, Alberta, Canada
Guoqiang Qian Nanocor, Inc., Arlington Heights, Illinois, U.S.A.
Darilyn Roberts Crompton Corporation, Middlebury, Connecticut, U.S.A.
Wilhelm Schob er HiTalc Marketing and Technology GmbH, Schoconsult,
GmbH, Austria
Copyright © 2003 by Marcel Dekker, Inc.
William P. Steen Luzenac America, Englewood, Colorado, U.S.A.
Michael D. Wolkowicz Basell USA, Inc., Elkton, Maryland, U.S.A.
Thomas C. Yu ExxonMobil Chemical Company, Baytown, Texas, U.S.A.
Copyright © 2003 by Marcel Dekker, Inc.
1
Global Trends for Polypropylene
Michael J. Balow
Basell Polyolefins USA, Inc., Lansing, Michigan, U.S.A.
1.1 INTRODUCTION
Polypropylene (PP) underwent phenomenal growth in production and use
throughout the world during the latter half of the 20th century. From the early
1960s until the oil crisis of the early 1970s, the growth rate was nearly 25%
annually. During the period from about 1974 through 1999, the rate of con-
sumption increased between 7% and 12% annually. This high growth rate
of PP consumption has required that production capacity keep up with the
growing demand. Though installed-capacity utilization has typically ranged from

approximately 85% to nearly 98% during peak demand periods, for the most part,
supply and demand have remained in balance. However during the latter half of
the 1990s, gross national product (GNP) was increasing at a record pace and
many companies invested in new polyolefin capacity. With the average annual
growth rate (AAGR) approaching 12% in 1999, there was continued expectation
of high demand. However, a slowdown in the economy began during the latter
half of 1999. This slowdown, coupled with a significant increase in new plants
and debottlenecking of existing plants, created a very significant supply imbal-
ance position.
Copyright © 2003 by Marcel Dekker, Inc.
A typical world scale polyolefins polymerization plant has a life expectancy
of more than 25 years. The initial investment in a PP plant is about $150 MM,
and operational efficiencies are typically only achieved when operating at >85%
of nameplate capacity. This situation has led to a serious structural problem for
the industry.
Changes in the demand patterns have had an impact on the industry.
Growth of any commodity should ideally be based on demand factors. Poly-
propylene is used in a great number of end-use applications. Due to the relatively
low investment for manufacturing processes that utilize PP, the consumers of PP
can often move quickly into areas where labor costs are low. In addition,
transportation costs for the polymer between the production site and the consumer
can be a significant contributor to the cost of the polymer. These factors,
combined with the increased consumption of gasoline in developed regions,
have led to monomer being readily available in large quantities at refiners in
developed countries. However, some of the largest growth rate for PP is in less
developed areas.
Today PP still accounts for the largest consumption of propylene monomer,
followed by acrylonitrile, oxo chemicals, and propylene oxide. Given the choices
of downstream derivatives for propylene, many producers have considered PP as
one of the easiest means for dealing with excess supply of the monomer,

especially in the case of refinery operations. Many of the major producers of
polypropylene are also refineries, at least in North America and Europe. Without
adequate gas pipeline infrastructure found predominately in the gulf coast of
North America and the Western coast of western Europe, it is not very practical to
transport the monomer large distances by overland or sea. It is therefore likely
that into the 21st century we will see most capacity increases for PP move either
to refinery locations in developed countries or to locations much closer to the
source of the oil (especially the Middle East). Another complicating factor is tariff
protection for local PP production. Many regions are concerned about protecting
their investments in developing countries. Often tariffs do not apply to the articles
made from PP.
These combinations of factors have led to a very serious and unprecedented
problem of overcapacity as we enter the 21st century. Although we have noted a
reduction in the new plant announcements in 2001 and 2002, it will take a
considerable period of time, perhaps as long as 2004, until the supply–demand
balance is corrected.
Another factor for concern, as mentioned above, is that the production of
commodity plastic parts is largely moving to third world countries. The most
rapid growth rate for polypropylene consumption is Africa and the Middle East,
Asia Pacific, and Eastern Europe. These regions are all increasing consumption
rates faster than Japan or Wester n Europe or North America where the major
production is located.
Copyright © 2003 by Marcel Dekker, Inc.
Intermaterial competition versus other commodity plastics is also working
strongly in favor of selecting PP. The other major competitors in the commodity
market are high-density polyethylene (HDPE), polystyrene (PS), and polyvinyl
chloride resins. These are all less favorable on a cost per volume basis. Experts
predict that the growth rates of PP could be as high as 8.3% annually. This growth
will be spurred by continued expectations of relatively low cost, improvements in
performance due to new catalyst introductions, more efficient catalysts, and

strong growth in developing countries based on the Western world average per
capita consumption.
1.2 REGIONAL ISSUES
There are many economic issues that influence regional consumption (Fig. 1.1)
and growth rates (Fig. 1.2). The various contributing factors are given below for
each geographical region.
With a move to a single currency, Western European producers will have to
strive to remain price competitive. Lower labor costs in Eastern Europe will
increasingly attract conversion operations. Eventually the Middle East will put
significant pressure on this region. Today we see industry consolidation taking
FIGURE 1.1 Projected polypropylene consumption by region. j, Eastern
Europe; u, South America; u, Africa and Middle East; u, Japan;
, Asia
Pacific; u North America; u, Western Europe.
Copyright © 2003 by Marcel Dekker, Inc.
place between Middle Eastern and European producers. Improvements in
catalysis will lead to innovations that will further broaden PP competitiveness.
In this area as well, PP capacity will outpace consumption. Exports back to the
Middle East and Africa will help support this overproduction. Polypropylene
consumption and trends in recycling in Western Europe are being closely
followed.
In North America, PP producers are suffering from low margins. Leading
producers have strived to reduce costs to cope with this trend, but industry
consolidation will continue. From a market perspective, PP still has significant
inroads left in the automotive industry, especially in interiors. The North
American Free Trade Agreement (NAFTA) has removed the borders between
Canada, Mexico, and United States. As this occurs, more production is shifting to
Mexico, and eventually PP production is likely to increase there as transportation
costs increase.
China recently announced its intention to increase its PP production

capacity. Today it is the single largest impor ting nation. Still the per capita use
is far below that of the rest of the world, so we can anticipate China will be a net
importer for some time. The inhibiting factor to this occurring is a need to
develop a more effective transportation infrastructure. Transportation of goods
into and out of China’s interior is expensive. China already has approximately 65
producers. However, many are small and older plants. They use the propylene
feedstock from local refineries that have very limited alternative uses for the
monomer.
FIGURE 1.2 Regional growth rates for years 1999–2004.
Copyright © 2003 by Marcel Dekker, Inc.
The economy in the Asia Pacific region has just been through a very
difficult time. This has resulted in industry rationalization and joint venture
arrangements with Western producers. Consequently, PP manufacture has h ad
slower than expected growth. China’s import needs are the single largest driving
force for newer capacity in the region. Therefore, the stability and continued
growth of the Chinese market is the key to PP growth in the Asi a Pacific region.
India’s growth in local production is allowing increased conversion industry to
take place there. The ASEAN free trade area (Malaysia, Indones ia, Singapore,
Vietnam, Thailand) represents a big step in creating a common market for the six
member countries. Interregional trade of PP and it converted products will
increase at the expense of import from other regions.
Eastern and Central European plants are being designed for a planned
recovery of the economies. Historically, they have not been competitive on a
world market scale. However, often growth is inhibited by lack of hard currency
needed for these investments. In addition, feedstock alignment is difficult. Low
labor rates are attractive but political instability of the region keeps the risk high.
Steady growth will continue in South America and Mercosur market
countries where tariffs are imposed to protect local markets. Mercosur is the
Common Market of the South, which includes Argentina, Brazil, Paraguay, and
Uruguay. These tariff measures have resulted in higher prices and limited growth.

Investments in these regions are primarily made to upgrade quality. Local
economy is more or less sized to meet the local consumer needs. Demand is
focused on meeting packaging and household demands. Free trade agreements as
in Mercosur have created a greater homogeneous market size and make invest-
ment in the region more attractive. Currency stability in this region will conti nue
to be an important issue.
1.3 GROWTH IN CONSUMPTION BY APPLICATION TYPES
Figure 1.3 depicts PP consumption of end-use products manufactured by a variety
of conversion processes. Fibers are expected to grow at or near the average with
significant gains in spun-bonded fibers. Injection molding will continue to grow
as PP displaces other materials. Sheet application will grow in two predominate
areas. Soft PP will grow to displace some rubber applications, and rigid and
transparent PP will penetrate PS in the extrusion=thermoforming area. Lastly, PP
will continue to grow in some regions at the expense of engineering resins such as
PC=ABS, nylon, or modified polyphenylene oxide (PPO), polyurethane in
application such as wheel covers, instrument panels, body side molding, and
headlines.
Copyright © 2003 by Marcel Dekker, Inc.
1.4 SUPPLIERS AND CONSOLIDATION
Since the mid-1990s, we have seen significant consolidation of the PP industry.
This trend has been true in all major producing regions of Japan, Western Europe,
and North America. This consolidation has been led by the interests of being a
global supplier, interests in having critical mass for a sizable business, lower
margins, increased customer service expectation as PP moves into more nontradi-
tional markets, and a strong interest in having reliable outlets for the propylene
monomer. Often key synergies have been created by these consolidations. In
addition, as margins decrease, older plants can no longer remain cost competitive.
Even high-efficiency catalyst processes that have been installed in just 20 plants do
not have broad product capabilities (e.g., can only produce homopolymer). These
upgraded plants can be obsolete, even before their expected lifetime runs out.

Homopolymer and copolymer production for different geographical loca-
tions are given in Fig. 1.4. The location of production facilities has become an
important competitive advantage for shipping finished product or procuring
monomer. Also locations near deep-sea ports can have a significant advantage
to export product, especially in a local economic slowdown.
1.5 RECYCLING
In the face of huge capacity increases another issue is starting to take shape.
Reuse of PP is also on the increase. Some recycle streams of PP are now fully
FIGURE 1.3 Polypropylene consumption by conversion process. j, Year
2000; u, Year 2005.
Copyright © 2003 by Marcel Dekker, Inc.
integrated into the supply chain. These include postconsumer battery recycling
and packaging, postindustrial fiber reclaim, and defective painted thermoplastic
olefins from molding=painting operations. This trend will most likely signifi-
cantly increase as the end-of-life vehicle requirements, now in place for European
car producers, come into full reality. The recycling of PP tends to be very difficult
in other applications; since the material is not often used without some kind of
secondary operation. These include painting in automotive, metallization or
multilayer structures in packaging, and, most frequently, pigmentation that
limits secondary uses often to black colors.
Polypropylene itself remains a very viable fuel for burning when recycled
resin is depleted of its usefulness due to ultimate degradation resulting from
multiple extru sion passes. However, these same issues mentioned above are also
complications for burning. Problems associ ated with contaminants in the plastic
can be observed in some countries that have tended to use mixed reclaimed
plastics for fuel in cement kilns, e.g., particularly in Asia.
1.6 SPECIALTY POLYPROPYLENE
As the PP market continues to suffer from poor return on investment for
producers, most producers are seriously considering conversion to specialty
products. In Europe and Asia, most of the specialty products are produced by

the manufacturers of the PP itself. There seems to have been a different strategy
FIGURE 1.4 Homopolymer and copolymer production by region in years 2000
and 2005. u, Homopolymer 2000; u, copolymer 2000; j, homopolymer 2005;
u, copolymer 2005.
Copyright © 2003 by Marcel Dekker, Inc.
in North America. In that region, most of the specialty PP products have been
produced by compounders and distributors. While this trend tends to be effective
in regional markets, the cost to users of these products on a global basis can go
up. In addition, as these products are used in more specialty applications, regional
compounding companies frequently lack the capability to support market
demands globally. Furthermore, some of the specialty items have reached suf-
ficient volume to allow alternative processes to be more cost-effective in order to
reduce manufacturing costs. However, this trend could change as pressures to
recycle postconsumer PP back into main market stream continues to grow.
Some of the specialty products include filled and reinforced PP with new,
higher performance additives such as nanocomposites. Postreactor modifications,
such as grafting with functional monomers, has reached significant magnitude
that the bulk polymer properties in the polymer matrix are being changed. This
enhancement may surpass simple adhesive characteristics between polymer
matrix and filler–glass fiber reinforcement that are attributed to functional
groups like maleic anhydride and acrylic acid, described in Chapter 3 of this
book. Also irradiation techniques used to branch PP are widely known; however,
investment costs are very significant.
Another driving force for PP in specialty markets is the desire to have all
one polymer type present in an article. For example, the total recycling of
automotive parts can avert the need for land fills, which seriously impact the
environment. This has the significant benefit of allowing easier reuse at the end of
life. Increase in the use of specialty PP material is extending beyond automotive
applications. This broad-based market growth of specialty products can be seen in
Europe where new PP wire coating applications have originated outside the

automotive industry.
1.7 CONCLUSIONS
The challenges that lie ahead for the PP industry will be significant. However,
products based on this polymer resin, borne out of a relatively simply, widely
available monomer, have proven to be very versatile in all-around performance.
Therefore, we can expect that PP resins will continue to be one of the major
choices of raw materials of construction for mankind well into the future.
REFERENCES
1. J Hoffman. Polypropylene beginning to show signs of strength. Chemical Market
Reporter, March 11, 2002, p. 8.
2. R Brown. Polypropylene producers seek 5-cent increase. Chemical Market Reporter,
January 28, 2002, p. 6.
Copyright © 2003 by Marcel Dekker, Inc.
3. J Hoffman. Petrochemicals outlook cloudy for the near term. Chemical Market
Reporter, January 7, 2002, p. 6.
4. F Esposito. PS, PP prices manage to rise since Feb. 1. Plastics News, March 18,
2002, p. 4.
5. R Brown. Commodity resins face uncertainty. Chemical Market Reporter, January 7,
2002, p. 4.
6. AMI. European plastics demand keeps on rising. European Plastics Industry Report,
June 20, 2000.
7. C Platz. Opportunities and challenges in polypropylene. Polyolefins International
Conference, Houston, February 26, 2001.
8. Basell. Polyolefins Design Manual, October 2001.
9. Polypropylene Annual Report 2000, Phillip Townsend and Associates.
10. Phillip Townsend and Associates. Global polyolefins consumption better than
expected. The Townsend Profile, Vol. 56, June 2001.
Copyright © 2003 by Marcel Dekker, Inc.
2
Polypropylene: Structure, Properties,

Manufacturing Processes,
and Applications
William J. Kissel and James H. Han
BP Amoco Polymers, Inc., Alpharetta, Georgia, U.S.A.
Jeffrey A. Meyer
BP Amoco Corporation, Naperville, Illinois, U.S.A.
2.1 TYPES OF POLYPROPYLENE
Polypropylene (PP) is a thermoplastic material that is produced by polymerizing
propylene molecules, which are the monomer units, into very long polymer
molecule or chains. There are a number of different ways to link the monomers
together, but PP as a commercially used material in its most widely used form is
made with catalysts that produce crystallizable polymer chains. These give rise to a
product that is a semicrystalline solid with good physical, mechanical, and thermal
properties. Another form of PP, produced in much lower volumes as a byproduct of
semicrystalline PP production and having very poor mechanical and thermal
properties, is a soft, tacky material used in adhesives, sealants, and caulk products.
The above two products are often referred to as ‘‘isotactic’’ (crystallizable) PP
(i-PP) and ‘‘atactic’’ (noncrystallizable) PP (a-PP), respectively.
Copyright © 2003 by Marcel Dekker, Inc.