Sustainable plastic manufacturing

The process, the challenges, and the alternatives. By Grethe Bestbier.

Plastic has received a bad reputation in recent years, but it’s still widely used. Charl Morkel is the co-owner of plastic manufacturer Patagon Flex Plastics. His company’s products include packaging systems for the fruit industry. He holds the view that making plastic is not the problem. The problem is what happens to the plastic after it’s used.

Making plastics

Polyethylene — the main plastic in many fruit bags — is made from the by-products of petroleum manufacture. When crude oil is refined through fractional distillation, gases such as ethene, propene, butene and hexene are produced. A combination of these gases is used to make different polymers. Morkel says that, as long as people are powering engines with petroleum products, the ingredients for polyethylene will be there.

Plastics such as polyethylene are supplied as pellets to converters who manufacture bags and other packaging products. Converters have a responsibility to work in a sustainable and environmentally friendly manner, says Morkel. Good manufacturing practices are crucial. “No spillage of raw material pellets is allowed. It is immediately swept up. This is done to prevent the possibility of environmental pollution, should any of this material end up in our storm-water systems. We rework all our factory scrap, nothing is discarded.”

Other green manufacturing practices include replacing old machines with more efficient ones to reduce electricity costs and carbon emissions.

Morkel says that it’s important for plastic converters to communicate with their clients to find possible design improvements. Buyers of single-use plastics need to constantly re-evaluate their packaging systems in order to find out the minimum amount of plastic needed to preserve fruit quality. Can they reduce film thickness? Is there a way to limit unnecessary secondary packaging?

Food for thought

Packaging for food tends to be more complicated than for other items. According to Morkel, food safety is a critical consideration that limits his company’s ability to use post-consumer recycled plastic in their products. When you eat an apple, you want to know that its packaging is safe. If the origin of the recycled plastic is not known, it can be potentially dangerous to the consumer.

“That is why Patagon Flex currently uses 100% virgin plastic to produce fruit packing bags destined for the export market. Otherwise, we would never be able to issue a food safety declaration for our products,” says Morkel. “At this stage the four main products made out of post-consumer recycled polyethylene are irrigation pipes, refuse bags, plastic carrier bags and plastic furniture.”

Another challenge is printed plastics. As Morkel explains, printed plastic can’t be recycled to make clear or colour-specific products. Recycled printed plastics have black pigment added to standardise the colour and therefore only black products can be made.

There are also cost implications. The price difference between virgin and recycled plastic was quite significant a few years ago with clear recycled polymer much cheaper than virgin polymer. That is no longer true. “If there were a large price difference, there would be a price incentive to add clear recycled material to our product, but then again, food safety would be an issue,” says Morkel.

Morkel states that they do use recycled plastics — up to 75% — for products that are not food-related. He believes that economic factors shouldn’t be the only driving force. “You should produce and use recycled material because it’s the right thing to do. It contributes to creating a cleaner environment by reducing plastic pollution. You should do it because it will reduce the impact that single-use plastic currently has on the environment, including our oceans.”

Going beyond recycling

Alternatives to recycling are becoming more viable. One is oxy-biodegradable plastics, which are meant to lighten the environmental load by self-degrading in the presence of oxygen, heat, and sunlight. Unfortunately oxy-biodegradable plastics are not suitable for recycling, as they begin to degrade when heated during the recycling process.

Natural polymers also have drawbacks. Polylactides and corn-starch plastics are both made from natural products and degrade easily, but can cost up to ten times more than a polyethylene alternative. These so-called bioplastics cause problems when misidentified at waste separation facilities. “If not identified correctly at the recyclers, they will contaminate the recycled polyethylene,” cautions Morkel.

An interesting alternative to speed the breakdown of plastics has been developed in joint research between Ben-Gurion University in Israel and counterparts in Canada. The scientist identified microorganisms that can digest plastics from landfill sites and domestic compost heaps. “They then developed a substance that can be added to polyethylene that attracts these microbes,” Morkel says.”

But for now the simplest and most effective solution is still recycling. Not only will this clean up the environment, but it will also lead to the creation of many jobs. According to Morkel, awareness is crucial to unleash the full potential of recycling. “Advertising and marketing motivate people to buy something. In similar fashion products made from recycled polymers must be marketed as the new trend.”

Morkel is confident that plastics will continue to play a part in our futures. “Plastic is a wonderful thing,” he says. “We just need to use it responsibly and stop wasting it.”