Biodegradable plastics — Polylactic acid (PLA) - OKCHEM - Global B2B Platform for Chemical Raw Materials

Biodegradable plastics — Polylactic acid (PLA)

2020.12.01

Environmental, economic and safety challenges have provoked packaging scientists and producers to partially substitute petrochemical-based polymers with biodegradable ones. Biodegradable can be degraded under the action of microorganisms or compost and have the characteristics of environmentally friendly, non-toxic and biodegradable.. Biodegradable plastics applied now include starch blends made of thermo-plastically modified starch and other biodegradable polymers as well as polyesters such as polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS).

Primarily starch blends with low cost account for 21.3% in global production capacity 2019 by material, but their performance and applications are limited as natural material. Then PLA and PBAT, are striking in biodegradable group. As the major driver of growth in the field of biodegradable materials, PLA and PBAT are the biodegradable material with currently the largest output, the widest application range, the highest cost performance and the closest to petro-based polyester in the world.

The advantages of PLA

Polylactic acid (PLA) is a thermoplastic, high-strength, high-modulus polymer that can be made from annually renewable resources to yield different components for use in either the industrial packaging field or the biocompatible/bioabsorbable medical device market. It is easily processable on standard plastic equipment to yield molded parts, film, or fibers.

1. Renewability of raw material

The raw material mainly comes from biomass formed by photosynthesis.

2. Complete biodegradability

It can be absorbed by body metabolism. After discarded, it will be degraded into CO2 and H2O by microorganisms in the soil or sea water under landfill condition, realizing the carbon cycle on the earth’s surface.

3. Human body’s affinity and safety

Lactic acid is endogenous in the human body. PLA can be decomposed into lactic acid metabolism and absorbed in the human body. It is classified as generally recognized as safe (GRAS) by the United State Food and Drug Administration (FDA) and is safe for all food packaging applications.

4. Excellent processing performance

PLA’s processing temperature is between 170 to 230 ℃, which can be processed in a variety of way, such as extrusion, spinning, biaxial stretching, injection, blow molding, foaming, plastics and so on.

5. Natural bacteriostasis

The antibacterial rate against candida albicans, escherichia coli and staphylococcus aureus is over 95%.

6. Natural flame retardancy

The oxygen limit index is 26%-27%, which is superior to common polyester and other materials , with low smoke or no black smoke.

7. Other features

It has excellent gloss, transparency, skin-feeling, UV resistance and moisture permeability.

Compared to petrochemical material, the most obvious physical index is high transmittance.

Item	PP	GPPS	PET	PLA
Density (g/cm3)	0.90—0.91	1.04—1.09	1.3—1.4	1.25
Melt index (g/10min)	0.2—20	1.5—30	—	1—30
Tensile strength (MPa)	29.6—35	≥58.8	≥60	≥50
Elongation (%)	200—700	1.0—2.5	30—70	≥5
Transmittance (%)	85—88	88—92	90—92	90—95

Compared to other biodegradable materials, PLA has advantages in hardness and transmittance, as well as production cost. The performances of PHA, PBS/PBSA and PBAT are similar because monomer molecular structure of their upstream materials are similar, with advantages of thermostability, strength and hydrolysis resistance. Therefore many products are produced by these composite material.

	Starch blends	PLA	PHA	PBS/PBSA	PBAT
Thermostability	o	++	+++	+++	+++
Film-forming	++	--	++	++	++
Hardness	o	+++	-	o	-
Mechanical strength	+	++	+++	+++	+++
Hydrolysis resistance	+	-	+++	+++	+++
Transmittance	-	+++	-	-	-
Production cost	lowest	lower	highest	higher	higher

+++ best, ++ better, + medium, o not good, - bad, --worse

The production and application of PLA

Polylactic acid is produced by fermentation of high-gloss pure lactic acid from starch biomass such as corn or straw cellulose. The lactic acid is prepared into ring dimer lactide, and then the lactide is ring-opened and polymerized to produce poly lactic acid.

PLA has good machanical properties, low shrinkage, and is competent to the application of most synthetic plastics, also it's widely used in the production of package materials, disposable tableware, household electrical appliance shell, fiber, 3D supplies etc.

Polylactic acid fiber, known as corn fiber, is made of corn fiber. It has weak acidity similar to human skin, natural skin-friendly, antibacterial, anti-mites, good drapability, moisture permeability, luster and silk-feeling, UV resistance widely used in underwear, sportswear and bedding. The PLA fiber can produce spunlace non-woven fabrics, hot air non-woven fabrics spunbonded non-woven fabric, needle punched non-woven fabrics by pure spinning or blending, with different processes, and also can be directly used to produce spinning adhesive and melt-blown non-woven fabrics.

PLA polyester is mainly applied in film products, daily products, industrial plastic products, medical products, 3D printing supplies and so on.

The global production capacity of biodegradable plastic

Currently bioplastics represent about one percent of the about 360 million tonnes of plastic produced annually. But, as demand is rising, and with more sophisticated biopolymers, applications, and products emerging, the market is continuously growing.

According to the latest market data compiled by European Bioplastics in cooperation with the research institute nova Institute, global bioplastics production capacity is set to increase from around 2.114 million tonnes in 2019 to approximately 2.426 million tonnes in 2024, and biodegradable plastics will increase from 1.174 million tonnes in 2019 to 1.334 million tonnes in 2024.

By now, one fourth of the global bioplastics production capacity is located in Europe, and Asia continues to be the major production hub, producing 45% in 2019. And next are in North America and South America.

With introduction of governments’ policies on petrochemical plastic bans, the demands on using the biomaterials made by biomass renewable resource to gradually replace petrochemical materials, will also increase gradually.

PLA, with environmental protection, non-toxic and degradable characteristics, is considered to be the most promising future of new biological materials to replace the traditional petro-based plastics (PE, PP, PVC, etc.) and petro-chemical fiber (PET, PTT, PBT, etc.).

OKCHEM PLA, PBAT and PBS Distribution Project

OKCHEM is the strategic partner of Anhui BBCA (the largest PLA producer in China) and Xinjiang Blue Ridge Tunhe (the largest PBAT producer in China) to look for buyers and partners globally. If you want to join us in this project, please contact us at info@okchem.com. You may also make the application online at: https://www.okchem.com/agent/detail/degradableplastics/oem