Understanding PLA

What is polylactic acid?

Polylactic acid (polylatic acid), referred to as PLA, also known as polylactide. It is a thermoplastic polymer obtained by artificial chemical synthesis of lactic acid produced by biological fermentation, and has good biocompatibility and biodegradability.

English name: polylactide, polylactic acid, PLA

English alias:polytrimethylenecarbonate;1,3-Dioxan-2-one homopolymer

Molecular formula: (C3H6O3)n

There is a hydroxyl group and a carboxyl group in a single lactic acid molecule, multiple lactic acid molecules together, -OH dehydration condensation with -COOH of other molecules, -COOH dehydration condensation with -OH of other molecules, in this way, they form hand in hand The polymer is called polylactic acid. Polylactic acid, also known as polylactide, belongs to the family of polyesters. Polylactic acid is a polymer obtained by polymerizing lactic acid as the main raw material. The raw material source is sufficient and can be regenerated. The production process of polylactic acid is non-polluting, and the product can be biodegraded to realize the cycle in nature, so it is an ideal green polymer material.

Basic performance

Polylactic acid (H-[OCHCH3CO]n-OH) has good thermal stability, processing temperature is 170-230°C, has good solvent resistance, and can be processed in various ways, such as extrusion, spinning, biaxial stretching , Injection blow molding. In addition to being biodegradable, products made of polylactic acid have good biocompatibility, gloss, transparency, feel and heat resistance, and can be used as packaging materials, fibers and nonwovens, etc., mainly for clothing (underwear) , outerwear), industry (construction, agriculture, forestry, paper) and medical and health fields.


  1. Advantages


(1) Polylactic acid is a new type of biodegradable material. It has good biodegradability. After use, it can be completely degraded by microorganisms in nature, and finally produces carbon dioxide and water. It does not pollute the environment, which is very beneficial to the protection of the environment. It is recognized as an environmentally friendly material.


(2) Good mechanical and physical properties. Polylactic acid is suitable for various processing methods such as blow molding and thermoplastic, and is easy to process and widely used.


(3) Good compatibility and degradability. Polylactic acid is also widely used in the medical field, such as the production of disposable infusion sets, surgical sutures, etc., and low-molecular polylactic acid as drug sustained-release packaging agents.


(4) In addition to the basic characteristics of biodegradable plastics, polylactic acid also has its own unique characteristics. Traditional biodegradable plastics are not as strong, transparent and resistant to climate change as ordinary plastics.


(5) The basic physical properties of polylactic acid and petrochemical synthetic plastics are similar, that is to say, it can be widely used to manufacture various application products. Polylactic acid also has good gloss and transparency, comparable to films made of polystyrene, which other biodegradable products cannot provide.


(6) Polylactic acid has the best tensile strength and ductility, and polylactic acid can also be produced by various common processing methods.


(7) Polylactic acid film has good air permeability, oxygen permeability and carbon dioxide permeability, and it also has the property of isolating odor.


(8) When polylactic acid is incinerated, its combustion calorific value is the same as that of incinerated paper, which is half of that of traditional plastics (such as polyethylene), and incineration of polylactic acid will never release toxic gases such as nitrogen and sulfide. The human body also contains lactic acid in monomeric form, which indicates the safety of this decomposing product.


  1. Disadvantages


(1) There are a large number of ester bonds in polylactic acid, which has poor hydrophilicity and reduces its biocompatibility with other substances;


(2) The relative molecular weight distribution of the product obtained by polymerization is too wide, and the polylactic acid itself is a linear polymer, which often makes the strength of the polylactic acid material unable to meet the requirements, high brittleness, and low heat distortion temperature (54°C under 0146MPa load) , poor impact resistance;


(3) The degradation cycle is difficult to control;


(4) The price is too expensive. The price of lactic acid and the polymerization process determine the high cost of PLA.


Application field


Mainly used in packaging bags, packaging films, medical films, foam plastics, tableware, etc.

PLA material has a smooth surface and a high degree of transparency, so it can compete with polystyrene and PET in some applications. PLA has been used in rigid packaging such as fruits and vegetables, eggs, cooked food and baked goods.

At present, most agricultural films are made of PE, but if they are replaced by degradable polymers such as PLA, it can not only reduce environmental problems, but also reduce the loss of plastic films.



Drug controlled release system, orthopedic fixation, tissue adsorption materials, surgical sutures, oral fixation materials, ophthalmic materials

4.3D printing

5.Other durable goods (electronic field, auto parts, etc.)


The modified polylactic acid PLA can improve the impact resistance, heat resistance, rigidity and flame retardancy of PLA. It has been widely used in the manufacture of computer parts, notebook casings, mobile phone parts, DVD player casings, CDs and home appliance parts, auto parts, etc. PLA can be multi-component blended with other resins, inorganic materials and other materials to produce products with New plastic "alloys" with excellent physical properties. These materials have excellent characteristics in antistatic, dimensional stability, tear strength, compressive strength, tensile strength, impact strength, etc., and are ideal new types of alloys. Eco-friendly synthetic material.

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