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Polypropylene Performance Developments Move Forward!

Donald Rosato – Jun 25, 2019

Polypropylene AdvancesPolypropylene (PP) is the second-most widely produced volume plastic after polyethylene. The global production of PP resin is 56 MMT (Million Metric Tons) in 2018 and is estimated to reach 83 MMT by 2025, at a CAGR (Compounded Annual Growth Rate) of 5.85%. The PP end-use market is US$97 billion in 2018 and will reach US$147 billion by 2025 for a 6% annualized growth.

The packaging sector represents more than 30% of global PP demand in 2018, driven by demand from number one India trailed by China.

Other major PP end-uses include:

 − Electrical/electronic and equipment manufacturing, both at approximately 13% each
 − Household appliances and automotive both consuming at 10% each
 − Construction materials follow at 5%, and
 − Very diversified applications together make up the remaining fifth of global PP consumption

Major PP resin suppliers include:

 − ExxonMobil
 − Borealis
 − Reliance Industries
 − LyondellBasell
 − Dow
 − Ineos
 − LG Chem
 − Dupont
 − Braskem
 − PetroChina, and
 − Sinopec

In order to be ahead in the market, it is important to stay up-to-date with improvements in PP resin developments. Let's take a look...

Polypropylene Resin Developments

Novel resin development is taking place in the field of high melt strength variants for use in foamed PP compounds. End-use markets for foamed PP include automotive, packaging, building and construction, and industrial. Key resin developers in this technology are Borealis, SABIC, and others such as Braskem and Japan Polypropylene.

PP Chemical Structure (L), PP Living Hinge from Bottle to Cap (R)
Credits: Plastics Institute of America

Borealis Daploy HMS PP Foaming Grade

High melt strength polypropylenes are tailored to have long chain branching that in turn gives them simultaneously their mechanical strength and elasticity. Borealis is the current market leader in the field with its Daploy™ HMS PP grade that exhibits a broad foaming range process window. Typical foam density for specific applications are:

 − 80-600kg/m3 (grams per cubic meter) in packaging applications such as cups or bowls
 − 40-350kg/m3 in automotive parts such as roof and door liners, impact absorbers, and ventilation ducts, and
 − 60-200kg/m3 in building insulation products

High melt strength and extensibility of Borealis HMS PP grades allow tailoring of foam properties by adding linear polymer component while keeping good foamability as shown in the two figures that follow:

Borealis HMS PP Force Versus Drawdown (L), and Tensile Modulus Versus Density (R)
Borealis HMS PP Force Versus Drawdown (L), and Tensile Modulus Versus Density (R)

Rheology Curves Comparing Traditional Linear PPs & Borealis Daploy HMS PP Foaming Grade
Rheology Curves Comparing Traditional Linear PPs (Green)
and Borealis Daploy HMS PP Foaming Grade (Orange)

In the above graphic, there is a rheological, contrast between traditional linear PPs and high melt strength (HMS) PP with its defined high-performance foaming window.

With HMS PP it is even possible to manufacture extremely low 20–50 kg/m3 density foams. These extruded foams have very finely delineated and uniform cell structure. These type foam structures are beyond the capability of standard linear PPs that fall well outside the high-performance HMS foaming window. Additionally, Borealis HMS PP is blendable with standard PP and broader polyethylene extrusion grades, as well as being processable on the vast majority of established foam extrusion equipment. This capability offers endless opportunities to custom tailor foams to very specific end-use applications and that these parts are fully recyclable.

Borealis HMS PP Applications
Borealis HMS PP Automotive Lining (L) and Food Container Foam Applications (R)

SABIC's Ultra Melt Strength (UMS) PP

Continuing, SABIC has continued to earnestly develop its version of a high melt strength PP. Their Ultra Melt Strength (UMS) PP resin grade has an excellent melt flow/strength of 65 centimeters Newton (cN). It is bringing unprecedented light-weighting levels to automotive applications such as interior instrument panel carriers, panel reinforcement pillars, and related flooring/guard supports.

Foaming technology with its strong focus on part wall downgauging is opening a broad array of sustainable applications in not only automotive, truck/bus, mass transportation, building insulation, but also packaging containers of all sorts to assist in minimizing food waste globally.

SABIC Foam PP Molded Instrument
SABIC Foam PP Molded Instrument Panel Carrier

Braskem's Amppleo 1025MA PP Grade

Next Braskem has been evolving their own branched, high melt strength PP. Their Amppleo 1025MA grade has a very good cost performance melt strength at 50 centimeters Newton accompanied by a flexural stiffness of 2.3 Giga Pascals (GPa). The development focus here is on low to medium density foam applications that utilize a broad range of chemical as well as physical blowing agents. It is quite adaptable to established inline and tandem extrusion manufacturing systems.

Metallocene Catalyzed Technology Based Japan Polypropylene's Waymax EX Grade

Finally, Japan Polypropylene is offering a high melt strength PP as a Waymax EX grade. It is based on metallocene catalyzed technology and exhibits a high melt flow rate, melt strength, and strong resistance to strain hardening. Their foamable grades possess high foam expansion ratios, in addition to consistent fine cell structure.

 » Continue reading to learn more about Polypropylene and Polypropylene blend material advances followed by recent additive developments for PP. 

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