Question

Please, I want a paragraph about PLA materiel, with a table of properties of PLA.

I need it in an experimental measurement and techniques project. NO PLAGIARISM PLEASE

Answer 1

Polylactic Acid (PLA)

Polylactic Acid (PLA) is different than most thermoplastic polymers in that it is derived from renewable resources like corn starch or sugar cane. Most plastics, by contrast, are derived from the distillation and polymerization of nonrenewable petroleum reserves. Plastics that are derived from biomass (e.g. PLA) are known as “bioplastics.”

PLA plastic or polylactic acid is a vegetable-based plastic material, which commonly uses cornstarch as a raw material. This material is a thermoplastic aliphatic polyester and it is the primary natural raw material used in 3D printing. PLA is a fully biodegradable thermoplastic polymer consisting of renewable raw materials.Among all 3D printing materials, PLA is part of the most popular materials used for additive manufacturing.

PLA is an aliphatic polyester, primarily produced by industrial polycondensation of lactic acid and/or ring-opening polymerization of lactide. Melt processing is the main technique used for mass production of PLA products for the medical, textile, plasticulture, and packaging industries. To fulfill additional desirable product properties and extend product use, PLA has been blended with other resins or compounded with different fillers such as fibers, and micro and nanoparticles.

The use of PLA was initially limited to medical applications due to its high cost and low availability, but high Mw PLA now can be processed by injection molding, sheet and film extrusion, blow molding, foaming, fiber spinning, and thermoforming. Also, PLA provides comparable optical, mechanical, thermal, and barrier properties when compared with commercially available commodity polymers such as polypropylene (PP), poly(ethylene terephthalate) (PET), and polystyrene (PS), expanding its commercial range of applications.

A vast array of applications for Polylactic Acid. Some of the most common uses include plastic films, bottles, and biodegradable medical devices (e.g. screws, pins, rods, and plates that are expected to biodegrade within 6-12 months). For more on medical device prototypes (both biodegradable and permanent). PLA constricts under heat and is thereby suitable for use as a shrink wrap material. Additionally, the ease with which Polylactic Acid melts allows for some interesting applications in 3D printing (namely “lost PLA casting” - read more below). On the other hand, its low glass transition temperature makes many types of PLA (for example, plastic cups) unsuitable to hold hot liquid.

PLA resin production

Lactic acid (LA), also named 2-hydroxy propionic acid, is the basic monomer of PLA. The monomer exists as two stereo isomers, L-LA and D-LA. the different chemical structures of these two isomers.The two main methods to produce LA are by bacterial fermentationof carbohydrates or by chemical synthesis . Bacterial fermentation is the preferred industrial process used by NatureWorks LLC andCorbion the two major producers of PLA. Chemical synthesis has many limitations, including limited production capacity, inability to produce only the desired L-LA isomer, and high manufacturing costs.

Polylactic Acid is principally made through two different processes: condensation and polymerization. The most common polymerization technique is known as ring-opening polymerization. This is a process that utilizes metal catalysts in combination with lactide to create the larger PLA molecules. The condensation process is similar with the principal difference being the temperature during the procedure and the by-products (condensates) that are released as a consequence of the reaction.

Selected average optical, physical, mechanical, and barrier properties of PLA

In contrast, PLA will be less durable, more fragile, and more sensitive to heat than ABS. PLA has a glass transition temperature of 65 °C and a melting temperature of 178 °C. PLA is not the most heat resistant material, this is why it is particularly suitable for decorative objects with no mechanical constraints.

To manufacture parts subject to major limitations, using ABS is preferable if you want to manufacture your part with FDM technology. The layer thickness varies between approximately 70 and 400 microns and depends on the 3D printer’s precision. Using polyamide powder sintering technology will provide even better results from a mechanical point of view.

There are several different types of Polylactic Acid to include Racemic PLLA (Poly-L-lactic Acid), Regular PLLA (Poly-L-lactic Acid), PDLA (Poly-D-lactic Acid), and PDLLA (Poly-DL-lactic Acid). They each have slightly different characteristics but are similar in that they are produced from a renewable resource (lactic acid: C₃H₆O₃) as opposed to traditional plastics which are derived from nonrenewable petroleum

Characteristics of Polylactic Acid

PLA is classified as a “thermoplastic” polyester (as opposed to “thermoset”), and the name has to do with the way the plastic responds to heat. Thermoplastic materials become liquid at their melting point (150-160 degrees Celsius in the case of PLA). A major useful attribute about thermoplastics is that they can be heated to their melting point, cooled, and reheated again without significant degradation. Instead of burning, thermoplastics like Polylactic Acid liquefy, which allows them to be easily injection molded and then subsequently recycled. By contrast, thermoset plastics can only be heated once (typically during the injection molding process). The first heating causes thermoset materials to set (similar to a 2-part epoxy) resulting in a chemical change that cannot be reversed. If you tried to heat a thermoset plastic to a high temperature a second time it would simply burn. This characteristic makes thermoset materials poor candidates for recycling.

Disadvantages of Polylactic Acid

PLA has a relatively low glass transition temperature (typically between 111 and 145 °F). This makes it fairly unsuitable for high temperature applications. Even things like a hot car in the summer could cause parts to soften and deform.

Polylactic Acid is a little bit more brittle than ABS for 3D prototyping but it has some advantages as well. For a full comparison of the two plastics as they relate to 3D printing read here