While PET and HDPE plastics are both excellent packaging materials, there are some notable differences which set these materials apart. First and foremost, it’s the appearance – PET is a clear plastic while HDPE is opaque.

In terms of stress cracking, PET bottles and containers have better resistance vs HDPE. HDPE is highly prone to environmental stress cracking due to its semi-crystalline nature. With higher molecular weight, crystallinity decreases thus plastic becomes more resistant to environmental stress cracking. Additionally, bottle-grade PET is amorphous and is engineered to prevent crystallization. If it crystallizes, it would lose its transparency as well as shows poor impact resistance.

HDPE containers are slightly more durable and temperature resistant, with a high operating temperature of 160° F compared to 145° F for PET bottles. As clarity is the most preferred feature of PET, it also has natural CO2 barrier properties to maintain food and beverage quality.

While HDPE is a cost-effective polymer, PET has better strength-to-weight ratio. Thus, more products can be delivered with less packaging – less waste. It reduces overall transportation cost as well as carbon footprint.

Today, sustainability and recyclability are becoming key aspects when it comes to material selection. Although both HDPE (code – 2) and PET (code – 1) are recyclable, the low diffusion coefficient makes PET much more suitable than other plastic materials for use as a recovered, recycled material. PET as well as rPET containers continue to remain a sustainable choice for food and beverage packaging industry.