Abstract
This webpage demonstrates the basic information of a biodegradable polymer --polylactic acid (PLA). PLA has good mechanical properties, processability, and biocompatibility but low toughness, more detailed can be seen in the “properties” page. The long literature review contains the sources, synthetic methods and polymer blend toughening of PLA. This page proofs the idea that using Polybutylene succinate（PBS）to improve the toughness of PLA is practical. We got the sample from the school of natural and applied science, NPU and we did serval experiments in the laboratory to test its thermal properties and measure the elongation at yield. PLA has good processability can be injected and extruded, the detailed procedure can be found in the “processing route“ & “manufacture” pages. PLA has a wide application prospect, it can be used in 3D printing, food packaging, tissue engineering, and biomedical field, now it has been used as the clinical operation thread.
Introduction
Polylactic acid（PLA） is a biodegradable polymer with good biocompatibility, it is derived from renewable resources such as corn and plant straw. It is expected to be an alternative to conventional petroleum-based polymer materials. PLA and Polybutylene succinate（PBS）are both aliphatic degradable polymers with good biocompatibility, they can be degraded into water (H20) and carbon dioxide(CO2) and be harmless to the human body. PLA has high mechanical strength, high modulus, and good processability. But PLA is brittle, poor toughness, and low crystallization, these drawbacks restricts its application. However, PBS has good toughness and a wide range of processing temperature so it can be used to make a physical modification of the PLA. In this poster, PLA was blended with PBS at a ratio of 7/3 for toughness improvement, and the sample is made into a dumbbell type by the hot pressing process. The press machine is used for mechanical performance testing, differential scanning calorimetry is used for crystallization measuring, and it was found that the toughness and crystallization of PLA have been improved. After physical improvement, PLA is expected to be used as a 3d printing material for human tissue engineering materials.
Fig 1 Granular polylactic acid
Property Profile
Table 1 Density of PLA & PBS
Table 2 Thermal properties
Table 3 (The properties of pure PLA)
Table 4 (The properties of PLA/PBS=7/3)
The data were measured by computer system tension testing machine. The curve was formed with the strain increasing.
Click to see specific PLA properties
Reflection
Click to see every members' reflection
What we learnt:
- The properties of material changes greatly with the composition of its ingredients, and we learnt a lot about the properties of PLA and PBS.
- We learnt some searching skills, in this process we gained access to a new searching engine, it is simple but powerful, we think it is good for our further study. In the meantime, we learnt how to clarify relevant information from different literature.
- We also reviewed our experiment in the laboratory, this program makes us think and combine the theory and the reality, it makes sense.
Literature Review
The white pollution caused by traditional non-degradable polymer materials has caused great pressure on the environment, while as a biodegradable material, polylactic acid (PLA) has a good application prospect.[1] In 2010, the PLA has the second highest consumption of bio-plastic in the world.[2] PLA can be obtained by direct condensation polymerization and lactide formation polymerization. Direct condensation polymerization is a direct dehydration of lactic acid monomer, but this method is difficult to obtain high molecular weight polylactic acid.[3] Lactide formation polymerization is ring-opening polymerization of propyl ester with metal catalysts in solution, which is sampler and cheaper.[4] PLA has high mechanical strength and high modulus[5] and good processability[6]. But its low toughness and low crystallization limits its broader application. Polybutylene succinate (PBS) has good toughness and thermal stability. So Lertwongpipat N[8] used PBS to improve the toughness of PLA, and studied the properties of a series of different quality ratio of the PLA/PBS. Polylactic acid was widely used in medicine and biology in the past, now it is expected to be a substitute for oil plastic products after improvement.[9]
Click to see Long Literature Review
Our samples
Fig 3 Pictures of our samples
Fig 4 the illustration of work had done
References
[1] Mukherjee T, Kao N. PLA based biopolymer reinforced with natural fibre : A Review[J]. Journal of Polymers and the Environment, 2011, 174(19):714-725.
[2] Ceresana. "Bioplastics Study: Market, Analysis, Trends Ceresana". www.ceresana.com. Archived from the original on 4 November 2017. Retrieved 9 May 2018.
[3] Murariu M, Dubois P. PLA composites: From production to properties[J].
Advanced Drug Delivery Reviews, 2016, 107: 17-46.
[4] Södergård, Anders; Mikael Stolt (2010). "3. Industrial Production of High Molecular Weight Poly(Lactic Acid)". In Rafael Auras; Loong-Tak Lim; Susan E. M. Selke; Hideto Tsuji. Poly(Lactic Acid): Synthesis, Structures, Properties, Processing, and Applications. pp. 27–41.
[5] Ahmed J, Varshney SK. Polylactides—Chemistry, Properties and Green Packaging Technology: A Review[J]. International Journal of Food Properties, 2011, 14(1): 37-58.
[6] Auras R, Harte B, Selke S. An overview of polylactides as packaging materials[J]. Macromol Biosci, 2004, 4:835–864.
[7] Qiang M, Qingfang Y, Junyan Y. Study on Synthesis of Poly (Lactic Acid) [J]. Polymer materials science and engineering,2004, 20(3):21-24.
[8] Lertwongpipat N, Petchwatana N, Covavisaruch S. Enhancing the Flexural and Impact Properties of Bioplastic Poly(lactic acid) by Melt Blending with Poly(butylene succinate)[J]. Advanced Materials Research, 2014, 931-932:106-110.
[9] Elsawya M A, Kimc K H, Deepb A, et al. Hydrolytic degradation of polylactic acid (PLA) and its composites [J].Renewable and Sustainable Energy Reviews, 2017, 79(14):1346-1352.
[10] Property Porfolio references from CES