Compostable alternatives for sanitary napkin raw materials

How to dispose a sanitary napkin? Have you heard of organic/ biodegradable/ compostable sanitary pads? Can sanitary napkins be 100% compostable? Can disposable products be recycled? What should be government’s policy around disposal of sanitary napkin waste?

This blog is a part of a series of 5 articles with the aim of answering some of the above questions and creating a complete picture of the life cycle of products to drive collective action towards better health and better environment.

Having discussed the pros and cons of compostable materials, let us look at commercial alternatives available for each of the raw materials used in making a sanitary napkin:

1. Perforated Polyethylene or non-woven Polypropylene as Top sheet. Properties of top sheet of sanitary napkin such as its softness, dryness or appearance is very important for a consumer. Technical parameters like Rewetting, Strike through etc. determine the performance of the material in keeping the top layer dry. Non-woven made of poly propylene often confused as cotton due to its texture, is not compostable. Non-woven PLA (Poly lactic acid) and other starch based non-woven plastics are as of today the most commercially available, industrially compostable option for replacing the polyethylene and polypropylene top sheets. The performance of these products are being worked upon to be able to match the performance of standardized products.
2. Polyethylene back sheet which acts as a barrier sheet can be replaced similarly with a PLA sheet. The top and back sheet together constitute for roughly 30% weight of a sanitary napkin
3. Wood pulp fluff or compressed wood pulp are made from pine wood. These bio based products are also known to be compostable. Certain binders or other additives could be added to improve the performance and they could be non-biodegradable.
4. Super absorbent polymers – Sodium/Pottasium Polyacrylates. These polymers play a key role in the absorption and retention properties of a sanitary napkin. These polymers are derived from petroleum products and are not biodegradable. There have been alternative developments of Bio-SAP and biodegradable hydrogels, but they are yet to meet the performance standards set by the commercial SAP.
5. Hot-melt adhesive is another petroleum based product that is used in a sanitary napkin. There are not many commercial adhesives available which are compostable.
6. Release liner is made of paper coated with silicone and is proven to be a compostable material.
7. Packaging pouch which is often made of Polyethylene can be replaced with PLA again.

To summarize this, some of the major plastic materials such as the top-sheet, back-sheet and packaging pouch can be replaced with alternative materials like PLA or other starch based products. More effort is needed by industry and institutes to develop adhesives and SAP which would be compostable and have a competitive performance. Some of the materials like cellulose/ wood pulp are already compostable and do not require replacement.

With the above mentioned alternatives, it would be possible to design a sanitary napkin which is 90% compostable by weight.

Price vs. Performance vs. Product acceptance

Consumers are more aware of the damage caused by plastics and are demanding for environmental friendly products as an alternative. However, it has been seen that the adoption to these newer materials has been limited. There are two primary reasons:

• Price: Due to the scale at which the new materials are produced and the cost of processing of raw materials being higher, these products cost much more than the commercial plastics (Cost of PLA is about 2.5 times cost of PE). As the processing technology and scale of consumption increases, we can expect the prices for these products to be more competitive.
• Performance: Even if consumers are willing to pay a higher price for these products, lower performance of these products tend to be a big hurdle to adoption. Hence it is important to invest into R&D to make sure the performance is at par with the commercial plastics.

At current stage, the performance of key compostable alternatives materials in a sanitary napkin (Top sheet, SAP) are poor compared to the standard materials and are also more expensive. Also, the supply of these alternatives is low which is why we have not seen any major purchase trend towards the compostable alternatives as of today.

In the next article we will look at a different approach of being environmental friendly, which is recycling the plastics. We will compare the pros and cons of recycling plastics vs. using alternate environment friendly plastics.