FTIR, DSC, and TGA analysis of the structural evolution and thermal behavior of maleic anhydride modified polylactic acid

Research Overview: A study published in Volume 164 of Polymer Testing was conducted to prepare maleic anhydride modified polylactic acid (MAH-g-PLA) through reactive melt processing. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were used in combination to investigate the structural evolution and thermal behavior during the modification process. The authors are Suchart Srichan, Prayoon Surin, and Somkiat Thermsuk, with a publication date of November 2026.

Characterization methods and focus

Study the changes in the molecular structure of polylactic acid after maleic anhydride grafting or reaction introduction using FTIR, obtain thermal transition information such as glass transition, cold crystallization, and melting using DSC, and evaluate the thermal stability and decomposition behavior of the material during the heating process using TGA.

. The three complementary methods: spectroscopy reflects the chemical structure, calorimetry reflects the phase transition and crystallization behavior, and thermogravimetric analysis reflects the thermal decomposition profile, together forming a descriptive framework for the structure performance relationship of modified polylactic acid.

Significance for the polymer additive industry

Polylactic acid, as a biodegradable polyester, also faces aging problems such as thermal oxidative degradation and hydrolysis during processing and use. Its degradation will change the molecular weight and carboxyl content, thereby affecting the melt processing window and product life.

. The multi method combination approach demonstrated in this study has methodological reference value for studying the mechanism of polymer aging and developing formulations for weather stability. FTIR can be used to identify the generation of degradation products such as carbonyl groups, DSC can reflect the crystallization and thermal transition drift caused by degradation, and TGA can quantify changes in thermal stability. In the design of stable systems, the commonly used antioxidant system for polylactic acid based materials needs to balance the stability of the melt during processing and the protection against thermal oxidative aging during long-term use; Outdoor application scenarios often introduce HALS (hindered amine light stabilizer) and UVA (ultraviolet absorber) to enhance weather resistance. Due to the difficulty of covering multiple requirements such as processing, thermal aging, and photoaging with a single additive, the design and validation of complex systems have become crucial. The determination of the effectiveness of such complex systems relies on systematic tracking of structural evolution and thermal behavior using characterization methods such as FTIR, DSC, and TGA. In addition, maleic anhydride modification belongs to reactive melting processing, and processing temperature, residence time, and reaction degree all affect the thermal history and stability of the final material. This study suggests that when evaluating modified polylactic acid or formulations containing such components, processing conditions should be interpreted in conjunction with thermal analysis results to avoid misjudging structural changes introduced by processing as aging or stabilization effects.

Industry Insights

For additive suppliers and modification companies, establishing a characterization combination based on FTIR, DSC, TGA can help quickly distinguish different failure paths such as processing stability, thermal oxidative aging, and photo aging in the formula screening stage, providing data support for the optimization of antioxidant and photo stable compound schemes.

. The study itself focuses on the structure and thermal behavior of modified polylactic acid, without involving specific additive formulations or weather resistance test conclusions. Its value mainly lies in the characterization method and the analytical framework related to processing structure performance.

Information source:Integrated FTIR, DSC, and TGA analyses of structural evolution and thermal behavior in maleic anhydride-modified polylactic acid prepared by reactive melt processing， Organized by Herun Chemical.