Physical Properties of Poly(lactic acid)/Hydroxyl Terminated Natural Rubber Blends

Abstract

Summary The objective of the study is to use hydroxyl‐terminated natural rubber (HTNR) as the toughening modifier for poly(lactic acid) (PLA). Photochemical degradation of natural rubber by ultraviolet radiation from high pressure mercury vapor lamp was used as depolymerization and hydroxylation of natural rubber. Molecular weight of HTNR was 25,000 (trueM‾n) and estimation of hydroxyl number of HTNR according to ASTM D4274‐11 was 2.04 mg KOH/g. The present of hydroxyl group was confirmed by FT‐IR, 1H‐NMR and 13C‐NMR spectrum. HTNR was blended with PLA in the ratio of 100/0, 100/3, 100/5, 100/10, and 100/15. Tensile and impact tests were carried out according to ASTM D638 and D256 respectively. It was found that tensile strength and tensile modulus of the PLA/HTNR blends were not significantly decreased whereas elongations at break were increased up to about 9 times compared with neat PLA. For impact properties, the results showed that impact strength of PLA was significantly increased up to 4 times with an addition of 10 wt% HTNR. SEM micrographs of the blends showed well disperse of HTNR particles and the occurrence of ductile fracture.

Polymer recycling in an open-source additive manufacturing context: Mechanical issues

“…Factors such as a decrease in the polymer chain length, reduction in the molecular weight, and increase in the degree of crystallinity induce the crack propagation above the elastic domain [63,94,98]. An experimental observation is that nominal strength at break after the first cycle seems relatively weak with respect to studies of mechanical properties using the same material PLA 4043D [99,100]. This could be attributed to differences in operating conditions during processing.…”

Hydroxylated Natural Rubber Effect on Crystallinity and Mechanical Properties of PLA

“…However, when the molecular weight of natural rubber is too low down to M ̅ n of 1.68 × 10 5 g/mol and M ̅ w of 3.19 × 10 5 g/mol, the elongation at break and the impact strength of PLA decreased. In 2015, S. Srisuwan and coworkers [2] had blended PLA with hydroxyl terminated natural rubber (HTNR; M ̅ n of HTNR = 2.5 x 10 4 g/mol) and with NR in the weight ratio of 90/10 at 170 o C with a rotor speed of 60 rpm for 10 minutes. It was clarified that the impact strength and elongation at break of PLA/HTNR and PLA/NR blends were measured being at 71.29 kJ/m 2 and 110.06% and 39.52 kJ/m 2 and 74.51%, respectively.…”