Other Performance
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Not only does clear polypropylene have the potential to be a less-expensive plastic packaging solution versus PET, due to a combination of raw material cost and lower density. Clear PP may also deliver excellent clarity plus the added benefits of a good stiffness / impact balance and improved moisture/ vapor barrier performance.
Good stiffness / impact balance:
Figure 1 illustrates the optimized balance of relative stiffness vs. impact strength for clear PP in comparison with other transparent materials.
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Figure 1: Relative Stiffness vs impact Strength
Good moisture / vapor barrier:
Twice better moisture barrier performance: PP has a distinct advantage for barrier performance over PET and many other transparent materials as illustrated in Table 1.
Improved protection against moisture permeation helps protect contents and extend shelf life.
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Table 1: Polypropylene properties vs other materials
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Desired Property
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PS
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PC
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PMMA
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SAN
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PET
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PVC
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Glass
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O2 Barrier Properties
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+
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+
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--
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-
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--
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-
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-
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H2O Barrier Properties
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++
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++
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+
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+
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+
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+
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-
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Key - PP with Milliad® NX8000 is better
Superior +++, Much Better ++, Better +, Worse -, Much Worse --
As a result, Clear PP provides a viable substitution for higher cost clear materials such as glass and clear plastics which have been traditionally used in injection molded or blow molded applications. These include water bottles, medical devices, appliances, and cosmetic and personal care packaging.