Packaging Materials: PET, PE, ALU — Complete Comparison

Introduction: why material choice is crucial

Packaging material is the foundation on which the entire packaging construction is built. It determines how long the product will stay fresh, whether it will survive transport, how it will look on the shelf, and how much you will pay for its production. Wrong material choice is not only a waste of money — it's a risk of complaints, returns, and brand reputation loss.

In the flexible packaging industry, several basic materials are used, from which hundreds of laminate combinations are created. This guide systematizes knowledge about the most important materials, compares their properties, and helps select the optimal structure for specific applications.

If you're looking for a general introduction to flexible packaging, start with our complete guide to flexible packaging.

Great comparison table of packaging materials

The table below summarizes key properties of all main materials used in flexible packaging:

Material	OTR (cm³/m²/24h)	WVTR (g/m²/24h)	Operating temperature	Transparency	Recyclability	Relative cost
PET (12 µm)	50-100	8-15	-40 to 200°C	Excellent	Yes (symbol 1)	Medium
metPET (12 µm)	0.5-1	0.5-1	-40 to 200°C	No (metallic)	Limited	Medium-high
BOPP (20 µm)	1500-2500	4-7	-30 to 140°C	Very good	Yes (symbol 5)	Low
metBOPP (20 µm)	10-30	0.5-1	-30 to 140°C	No (metallic)	Limited	Low-medium
PE-LD (50 µm)	3000-5000	10-15	-50 to 80°C	Good	Yes (symbol 4)	Low
PE-HD (25 µm)	1500-2500	3-5	-50 to 120°C	Medium	Yes (symbol 2)	Low
PA/Nylon (15 µm)	20-40	80-150	-60 to 200°C	Very good	Difficult	High
ALU foil (7 µm)	<0.1	<0.1	-40 to 300°C	No (metallic)	Yes (in pure form)	High
EVOH (5 µm)	0.1-1	80-150	-40 to 180°C	Excellent	Difficult	Very high
Paper (40 g/m²)	5000+	200+	-20 to 120°C	No	Yes (paper stream)	Low
Regenerated cellulose (20 µm)	500-1000	150-300	-10 to 150°C	Very good	Biodegradable	High

Note: OTR values given at 23°C, 0% RH. WVTR values at 38°C, 90% RH. Thicknesses are standard for flexible packaging — actual parameters depend on manufacturer and thickness.

PET (polyethylene terephthalate) — versatile leader

Properties

PET is one of the most commonly used materials in flexible packaging. Its popularity results from an exceptional combination of properties:

• Transparency — transparency at 89-91%, rivaling glass. Product is perfectly visible through packaging.

• Oxygen barrier — OTR 50-100 cm³/m²/24h at 12 µm, significantly better than PE or PP. Sufficient for many food products.

• Mechanical strength — tensile strength 170-200 MPa, highest among standard films. PET is the load-bearing layer of most laminates.

• Thermal stability — maintains properties from -40°C to 200°C, enabling pasteurization and microwaving.

• Printability — excellent surface for rotogravure and flexographic printing.

PET variants

• BOPET (biaxially oriented) — standard PET for laminates, strengthened in both directions.

• metPET (metallized) — with thin aluminum layer vacuum-deposited on PET. Barrier OTR drops to 0.5-1, WVTR to 0.5-1 g/m²/24h. Used as a cheaper alternative to full ALU foil.

• CPET (crystallized) — resistant to temperatures up to 220°C, used in oven trays.

• rPET (recycled) — from recyclate, approved for food contact (after super-clean process).

Typical PET applications

• Outer (printing) layer of laminates for coffee, snacks, frozen food.

• Stand-up pouch and doypack packaging.

• Supplement and pharmaceutical pouches.

• Cosmetic packaging (samples, sachets).

PE (polyethylene) — foundation of flexible packaging

Polyethylene is the most widely used polymer in the world — it constitutes over 30% of global plastic production. In flexible packaging, it mainly serves as the sealable and moisture barrier layer.

PE-LD (low density polyethylene)

• Density: 0.910-0.925 g/cm³
• Properties: flexible, soft, excellent sealability, good moisture barrier.
• WVTR: 10-15 g/m²/24h (at 50 µm) — not the best, but sufficient for many applications.
• Applications: inner sealable layer of laminates, film bags, stretch films, shrink films.
• Limitations: low temperature resistance (max 80°C), poor oxygen barrier.

PE-LLD (linear low density polyethylene)

• Density: 0.915-0.930 g/cm³
• Properties: stronger than LDPE at smaller thickness, better puncture and tear resistance.
• Applications: LDPE replacement in applications requiring greater strength, stretch films, garbage bags.
• Advantage: allows reducing film thickness by 20-30% while maintaining the same mechanical properties (downsizing).

PE-HD (high density polyethylene)

• Density: 0.941-0.965 g/cm³
• Properties: stiffer, more durable, better moisture barrier than LDPE.
• WVTR: 3-5 g/m²/24h (at 25 µm) — significantly better than LDPE.
• Temperature resistance: up to 120°C (short-term).
• Applications: thicker packaging, pasteurized products, containers, caps.
• Recyclability: symbol 2, widely recycled stream.

Aluminum foil — absolute barrier

Aluminum is the only material offering practically complete barrier against:

• Oxygen (OTR ≈ 0)

• Moisture (WVTR ≈ 0)

• Light (100%)

• Aromas (absolute)

Aluminum properties

• Thickness in flexible packaging: usually 7-12 µm (thinner than human hair)
• Barrier: doesn't decrease with time or conditions (unlike EVOH, which loses barrier in moisture)
• Formability: can be laminated with various materials
• Recyclability: 100%, infinite recycling without quality loss

When to choose aluminum?

• Products requiring maximum shelf life (coffee, tea, premium supplements)

• Products sensitive to light (vitamins, photosensitive ingredients)

• Products with strong aroma (spices, coffee)

• Export products (long transport and storage)

Environmental considerations

Aluminum production has high carbon footprint, but:

• Very thin layer (7 µm) means small material consumption per package

• Infinite recyclability offsets production footprint

• Growing availability of recycled aluminum

Paper — natural aesthetics with limitations

Paper in flexible packaging is mainly used as the outer layer in "eco" laminates. Its advantages and disadvantages:

Advantages

• Natural appearance — builds eco-brand perception

• Printability — excellent for flexographic printing

• Renewable raw material — from responsibly managed forests (FSC)

• Recyclability — in paper stream (when not laminated with plastic)

Limitations

• No barrier — OTR and WVTR very high, requires lamination with plastic

• Sensitivity to moisture — loses strength when wet

• Weight — heavier than plastic equivalents

• Limited forming ability — difficult to create complex shapes

Paper in laminates

Typical structure: Paper (60-120 g/m²) / PE or barrier layer / PE (sealable)

• Problem: Such "paper" packaging is actually paper-plastic laminate, which complicates recycling. Paper cannot be recycled with plastic layer, and plastic cannot be recycled with paper.

PP (polypropylene) — economical and durable

BOPP Properties

BOPP (biaxially oriented polypropylene) is a material with an excellent cost-to-performance ratio:

• Moisture barrier — WVTR 4-7 g/m²/24h, better than PET and PE-LD.

• Transparency — high, although slightly lower than PET.

• Thermal resistance — up to 140°C, which allows for pasteurization.

• Stiffness — good mechanical properties at low thickness.

• Cost — about 15-25% cheaper than PET.

PP Variants

• Transparent BOPP — standard for candy, bars, and pasta packaging.

• Matte BOPP — premium effect, soft touch, popular in cosmetics.

• metBOPP (metallized) — oxygen barrier drops to 10-30 cm³/m²/24h, the cheapest barrier option in packaging.

• Pearlized BOPP — white, opaque, ceramic effect, used in cosmetic and supplement packaging.

• CPP (Cast PP) — non-oriented, used as an internal sealable layer in laminates requiring pasteurization.

PA/Nylon — strength and oxygen barrier

Properties

Polyamide (nylon) stands out for its combination of mechanical strength and good oxygen barrier:

• Puncture resistance — highest among standard films. Ideal for packaging products with sharp edges (meat bones, frozen food with ice crystals).

• OTR: 20-40 cm³/m²/24h (at 15 µm) — good barrier, though lower than metPET and ALU.

• Thermal resistance — up to 200°C, enabling cook-in bags and retorting.

• Forming flexibility — PA can be deep-drawn (thermoformed) to create packaging with complex shapes.

PA Limitations

• Hygroscopicity — nylon absorbs moisture from the environment (up to 3% mass), which degrades the oxygen barrier and mechanical properties. Therefore, PA is ALWAYS laminated with PE (a moisture barrier layer).

• Cost — 40-60% more expensive than PET.

• Recyclability — PA/PE laminates are difficult to recycle in standard streams.

EVOH — oxygen super-barrier

Properties

EVOH (ethylene-vinyl alcohol copolymer) is a material with the highest oxygen barrier among polymers:

• OTR: 0.1-1 cm³/m²/24h (at 5 µm) — rivals aluminum foil.

• Transparency — excellent, unlike aluminum.

• Taste neutrality — organoleptically neutral.

Key Limitation

The EVOH barrier drops dramatically at high humidity. At 90% RH, the OTR value increases 10-50×. Therefore, EVOH is ALWAYS placed inside the structure, protected by moisture-absorbing PE or PP layers:

• PE/EVOH/PE — mono-material PE with EVOH barrier, recyclable.

• PET/EVOH/PE — premium barrier with a transparent outer layer.

• PA/EVOH/PE — maximum barrier and mechanical strength.

Laminates — combining materials for optimal properties

Why we laminate?

No single material meets all requirements simultaneously: oxygen barrier, moisture barrier, mechanical strength, sealability, and printability. Lamination involves combining 2-5 layers into a single structure, where each layer performs a specific function:

1. Outer layer (printing): PET, BOPP, paper — printability, mechanical protection, stiffness.
2. Barrier layer: ALU, metPET, EVOH, PA — oxygen and/or light barrier.
3. Inner layer (sealable): PE-LD, PE-LLD, CPP — sealability, moisture barrier, product contact.

Most popular laminate structures

Structure	OTR	WVTR	Typical Application
PET/PE	50-100	5-10	Snacks, candy, frozen food
metPET/PE	0.5-1	0.5-1	Coffee, tea, spices
PET/ALU/PE	<0.1	<0.1	Premium coffee, baby food
PA/PE	20-40	5-10	Vacuum meats, cheeses
PA/EVOH/PE	0.1-0.5	5-10	MAP meat, ready meals
BOPP/metBOPP	10-30	1-3	Chips, snacks
PET/PE (mono-PE)	80-150	8-12	Recyclable packaging
Paper/PE	3000+	10-15	Sugar, flour, dry products
PET/ALU/PA/PE	<0.1	<0.1	Retort, sterilized ready meals

Ecological aspects and recyclability

Recyclability hierarchy of materials

From easiest to hardest to recycle:

1. Paper and cardboard — well-developed recycling system, 85% recycling rate in the EU.
2. PET — best-recycled plastic, bottle-to-bottle system. Recycled PET (rPET) is approved for food contact.
3. PE-HD — well-recycled, but mainly into secondary products (pipes, benches).
4. PE-LD — recyclable, though less frequently collected selectively. Film recycling programs are growing.
5. PP — recyclable, but sorting and processing infrastructure is still developing.
6. Aluminum — theoretically infinitely recyclable, but thin packaging foils often end up in mixed waste.
7. Multi-material laminates — most difficult to recycle. Require separation technologies.

Material costs — economic comparison

The price of packaging material depends on many factors: base raw material, thickness, processing (orientation, metallization, coatings), order volume, and market situation. These are indicative market prices for 2026:

Material	Indicative price (EUR/m²)	Price drivers
PE-LD 50 µm	0.10-0.15	Ethylene price (oil derivative)
PE-HD 25 µm	0.06-0.10	Ethylene price
BOPP 20 µm	0.08-0.12	Propylene price
PET 12 µm	0.12-0.20	PTA and MEG prices
metPET 12 µm	0.18-0.25	PET price + metallization process
PA 15 µm	0.22-0.35	Caprolactam price
ALU Foil 7 µm	0.30-0.45	Aluminum price on LME
EVOH 5 µm	0.50-0.85	Specialized raw material, low volume
Barrier paper 60 g/m²	0.08-0.14	Cellulose price + coating

Summary: how to choose material for your product?

Use this decision tree:

Step 1: Barrier requirements

• Maximum barrier needed? → ALU or metallized film

• Good barrier sufficient? → PET with barrier coating

• Basic barrier enough? → Mono-PE or mono-PP

Step 2: Transparency

• Product must be visible? → Transparent PET or OPP

• Opaque packaging acceptable? → Metallized films, paper laminates

Step 3: Thermal resistance

• Pasteurization/sterilization? → PP or PET

• Ambient temperature? → PE sufficient

Step 4: Recyclability

• Priority: full recyclability? → Mono-material PE or PP

• Barrier more important? → Multi-layer laminate

Step 5: Budget

• Limited budget? → PE or PP structures

• Premium acceptable? → PET, ALU, or special barriers

Read more about ecological packaging solutions in our article on eco-friendly packaging trends.

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