Effect of thermo-mechanical cycles on the physico-chemical properties of poly(lactic acid)

Abstract. Low odour-emissive polylactide/cellulose fibre biocomposites, intended for car interior, were prepared and characterised. The impact of the different stages of processing (drying cycles, compounding, injection moulding) on the extent of polylactide degradation and on biocomposites properties was investigated by size exclusion chromatography, thermogravimetry, differential scanning calorimetry. In parallel, the odour emission of these materials was quantified via dynamic dilution olfactometry and Field of odours ® method. The changes in molecular weight and global odour emission indicated that compounding had a strong impact on polylactide degradation and odour emission, while injection moulding had no significant impact. Adding 0.5 wt% of an absorbent agent based on poly(1-methylpyrrol-2-ylsquaraine could) divide the global odour concentration by a factor 2. The morphology, mechanical and thermal properties of injection moulded PLAbiocomposites were not affected by the presence of the absorbent agent.

Section: Molecular Weightsupporting

confidence: 90%

Characterisation of low-odour emissive polylactide/cellulose fibre biocomposites for car interior

Courgneau¹,

Rusu²,

Henneuse³

et al. 2013

“…After the subsequent extrusion steps, the viscosity of PLA decreases likely due to polymer chain degradation (Figure 2b). The scientific literature reports three possible hypotheses for explaining degradation phenomena of the matrix occurring during processing: i) radical degradation, ii) hydrolysis and/or iii) transesterification with residual catalysts [41]. PLA + U-HT nanocomposites (Figure 2d) show the same trend as PLA as a function of reprocessing cycles.…”

Section: Resultsmentioning

confidence: 94%

“…These results can likely be attributed to the competition between two phenomena that occurs during reprocessing, i.e. the decrease of molecular weight and the increase of crystallinity that affect in an opposite way the stiffness of the material [41]. On the contrary, the mechanical performance of the material reinforced with OM-HT has a different trend.…”

Section: Resultsmentioning

confidence: 98%

Structure-properties relationships in melt reprocessed PLA/hydrotalcites nanocomposites

Scaffaro¹,

Sutera²,

Mistretta³

et al. 2017

Abstract. In this work the effect of multiple reprocessing was studied on molecular structure, morphology and properties of poly(lactic acid)/hydrotalcites (PLA/HT) nanocomposites compared to neat PLA. In addition, the influence of two different kinds of HT -organically modified (OM-HT) and unmodified (U-HT) -was evaluated. Thermo-mechanical degradation was induced by means of five subsequent extrusion cycles. The performance of the recycled materials was investigated by mechanical and rheological tests, differential scanning calorimetry (DSC), intrinsic viscosity measurements and SEM observation. The results indicated that the best morphology was achieved in the systems incorporating OM-HT. On increasing the extrusion reprocessing cycles, the properties showed behavior due to two opposite effects: i) chain scission due to thermo-mechanical degradation and ii) filler dispersion effect resulting from multiple processing. In particular, at low reprocessing cycles, both tensile and rheological properties seem to be mainly affected by HT dispersion, especially when OM-HT was added. After five reprocessing cycles, on the contrary, chain scission, i.e. thermo-mechanical degradation, dominated. As regards the effect of the presence of organic modifier in HT, the results indicated that this variable apparently did not affect the macroscopic performance of the nanocomposites, especially at high reprocessing cycles.

“…Pillin et al [46] examined the effect of a thermo-mechanical treatment on the properties of PLA. The rheological and mechanical properties of PLA subjected to thermo-mechanical cycles were determined.…”

Section: Thermal Propertiesmentioning

confidence: 99%

Properties and medical applications of polylactic acid: A review

Hamad¹,

Kaseem²,

Yang

et al. 2015

599

306

Abstract. Polylactic acid (PLA), one of the well-known biodegradable polyesters, has been studied extensively for tissue engineering and drug delivery systems, and it was also used widely in human medicine. A new method to synthesize PLA (ring-opening polymerization), which allowed the economical production of a high molecular weight PLA polymer, broadened its applications, and this processing would be a potential substitute for petroleum-based products. This review described the principles of the polymerization reactions of PLA and, then, outlined the various materials properties affecting the performance of PLA polymer, such as rheological, mechanical, thermal, and barrier properties as well as the processing technologies which were used to fabricate products based on PLA. In addition, the biodegradation processes of products which were shaped from PLA were discussed and reviewed. The potential applications of PLA in the medical fields, such as tissue engineering, wound management, drugs delivery, and orthopedic devices, were also highlighted.