Sodium polyacrylate

Sodium polyacrylate belongs to superabsorbent polymers with the chemical formula [−CH2−CH(CO2K)−]n.

In functionality, it can absorb hundreds of times its weight water then turns to water gel form.

In safety aspect, it’s non-toxic, non-pollutant, and harmless. It’s easy to find the MSDS (Material Safety Data Sheet).

Basic info

Appearance white powder/particle (turn to transparent crystal after absorbing water)
Odor imperceptible
CAS number 9003-4-7
Function Absorbing, retaining or to blocking liquid
Physical property Non-toxic, harmless, nonpolluting, natural degradation
Market price USD 800-3000 per ton (updated in 2018)

Mechanism

It consists of a set of polymeric chains that are parallel to each other and regularly linked to each other by cross-linking agents, thus forming a network.

When water comes into contact with one of these chains, it is drawn into the molecule by osmosis. Water rapidly migrates into the interior of the polymer network where it is stored.

Tip: Metal ion can deeply reduce or destroy the water absorbing capacity of sodium polyacrylate.

Production process

Types

There’re many types of sodium polyacrylate for different uses, such as:

  • starch-based type (which is biodegradable),
  • catalyst improved type (for water blocking of cable),
  • cation type (for concrete additive),
  • *defective type & recycled type (for waste liquid absorption).

Uses

Sodium polyacrylate can

  • be used directly;
  • be used as the raw material of products.

Here are the details:

1. Be used directly

  • for production

water blocking, inflatable rubber, thickening agent, fire-retardant gel, desiccant agent, thermal storage agent.

  • for building

concrete protection, anti-foggy agent.

  • for environment

waste liquid control, excreta collection.

  • other

drilling fluid, collection of tattoo liquid waste, oil-water separation.

2. Be used as a raw material

  • products for animals

pet pad, drown-free water source for feeder insects.

  • products for personal care

paper diaper, sanitary napkin, nursing mat, contact lenses.

  • products in home

ice pack, fragrance carrier, water beads, growing toys, cosmetics, solid waterbed.

  • other

cable, urine bag, anti-flood bag, instant snow, waterproof paint.

FAQs about sodium polyacrylate

1. Is it safe to eat sodium polyacrylate?

It’s safe to eat it.

The pharmaceutical grade sodium polyacrylate is totally nontoxic. As a safety water gel material, it can be even used in body implants such as artificial vitreum and artificial skin.

For other grade sodium polyacrylates, the only poisonous substance is the acrylic acid. Its content is less than 1000 PPM and won’t be harmful when to eat.

But as a highly absorbent material, it would bring stomach discomfort to eat sodium polyacrylate.

2. Is sodium polyacrylate safe for plants?

Safe but not recommend.

Sodium polyacrylate would be decomposed into Sodium ions which cause soil salinization.

3. How can I get sodium polyacrylate?

Sodium polyacrylate can be used in everywhere. We can easily get it from paper diapers, sanitary towel or nursing pad.

4. Can you reuse sodium polyacrylate?

Yes. It can be reused indefinitely. But it’s important to avoid direct sunlight and high temperature.

5. What is the use of sodium polyacrylate?

It can be used as:

a. water retaining agent (for plants);

b. water absorbent material (for diapers);

c. expanding material (for inflatable toys);

d. thickener (for cosmetics);

e. water blocking material (inflatable sandbag);

f. cooling storage (ice pad).

6. How Sodium polyacrylate is made?

It’s polymerized by Sodium acrylate (which made by sodium hydroxide and acrylic acid).

The production process is:

a. sodium hydroxide + acrylic acid -> sodium polyacrylate (semi-finished);
b. sodium polyacrylate (semi-finished) -> drying -> smashing -> sift out -> sodium polyacrylate.

Further Details