Heat Resistance of Packaging: Foam vs Molded Pulp — Which Performs Better in Hot Climates?

Sarnti Green Pack
Apr 22
3 min read

When “Heat” Becomes a Critical Factor in Transportation

In today’s global supply chain, international shipping has become the norm. Packaging is no longer just about “wrapping a product”—it must also withstand a wide range of environmental conditions, especially high temperatures. In tropical countries like Thailand, or during ocean freight, temperatures inside shipping containers can reach 50–70°C after prolonged exposure to sunlight. At this level, heat can directly impact packaging performance. Many businesses still rely on foam materials (EPS / EPE) for cushioning. However, there is a growing shift toward Molded Pulp, as it offers both performance and sustainability.

This article will help you understand:

How heat affects packaging
Which material—foam or molded pulp—is more suitable for hot climates

How Does Heat Affect Packaging?

Before comparing materials, it’s important to understand how heat impacts packaging systems:

1. Structural Degradation

High temperatures can cause certain materials—especially plastics—to soften and lose strength.

2. Deformation

Heat Resistance of Packaging: Foam vs Molded Pulp — Which Performs Better in Hot Climates?

Heat can lead to:

Warping
Shrinking
Shape distortion

This directly reduces the packaging’s ability to protect products.

3. Adhesive and Tape Failure

In carton-based packaging systems:

Adhesives may melt
Tapes may lose adhesion

This increases the risk of boxes opening during transit.

4. Static Electricity

In hot and dry conditions, some materials (especially foam) can accumulate static electricity, which may damage sensitive electronic components.

Foam Used in Packaging

Common types of foam used in packaging include:

EPS (Expanded Polystyrene)

EPE (Expanded Polyethylene)

These materials are widely used because they are lightweight and provide good cushioning.

✅ Advantages of Foam

Lightweight, helping reduce transportation costs
Good shock absorption
Relatively low cost per unit

❌ Limitations in Hot Environments

1. Heat Sensitivity

EPS foam begins to soften when exposed to heat. With prolonged heat exposure, it may cause:

Shrinkage
Deformation

(PlasticsEurope, 2022)

2. Dimensional Instability

When stored in hot containers:

Foam may warp
Or deform unevenly

This can cause products to become loose and shift during transport.

3. Static Electricity

Foam can accumulate static electricity, posing risks to:

PCBs
Electronic components

4. Environmental Concerns

Foam:

Is difficult to decompose
Creates long-term waste

(UNEP, 2021)

Molded Pulp: A More Stable Alternative

What is Molded Pulp?

Molded pulp is made from:

Recycled paper (OCC)
Office paper waste

It is formed into packaging that fits the product precisely.

✅ Advantages in Hot Conditions

1. High Thermal Stability

Molded pulp is made from cellulose fibers, meaning it does not melt like plastic:

No shrinkage
Less prone to deformation

2. Strong Structural Integrity

Even in high temperatures:

Shape remains stable
Products are securely held in place

3. Breathability

Its porous structure allows airflow, helping to:

Reduce heat buildup
Minimize moisture accumulation

4. No Static Electricity

Safe for:

Electrical devices
Static-sensitive components

5. Environmentally Friendly

Molded pulp:

Is biodegradable
Is recyclable
Can reduce CO₂ emissions by up to 90–95% compared to foam

(Ellen MacArthur Foundation, 2019; ScienceDirect, 2022)

Suitable Industries for Molded Pulp

1. Electronics

Reduces static + heat resistant

2. Furniture

High load-bearing + maintains shape

3. Agriculture / Food

Good ventilation

4. Consumer Goods

Maintains product form

📊 Comparison: Foam vs Molded Pulp

Property	Foam (EPS/EPE)	Molded Pulp
Heat Resistance	Moderate (may soften)	High
Shape Retention	May deform	Excellent
Static Electricity	Risk present	None
Breathability	Low	High
Sustainability	Non-biodegradable	Biodegradable
Suitability for Hot Climate	Limited	Highly suitable