Structure–property relationship for poly(lactic acid) (PLA) filaments: physical, thermomechanical and shape memory characterization

Abstract

Physical, thermomechanical, and shape memory properties of two different samples of poly(lactic acid) (PLA) multifilament yarns were determined using various complementary techniques. The birefringence and crystalline fraction of one sample was higher than the other filaments sample indicating higher molecular orientation and compactness. For both filaments, two distinct morphological features with different sizes in the order of few nanometers (less than 50 nm) were found using AFM and SAXS techniques. The glass transition temperature (T g ) of the samples were ranged from 61°C to 76°C depends on the sample and the methods of measurement. Partial storage modulus (E′) increase above T g as well as additional small peak in loss modulus (E″) of the lower crystallinity sample was assigned to recrystallization. The multiple overlapped peaks in the E″ and tan δ curves and subsequent crystallization along with exothermic peak right after T g suggests the existence of both relaxed and oriented amorphous regions. The rigid crystalline regions prevented the shrinkage and enhanced dimensional stability. Multifilament yarn with higher crystallinity and total molecular orientation showed higher modulus (both dynamic and static) and strength and lower elongation at break. The oriented noncrystalline regions in the multifilament yarn sample led to moderate modulus and strength along with high elongation at break. The shape recovery of both samples with different structural parameters stayed almost constant (~50 %) upon the deformation temperature rise.

Biodegradable polyester-based shape memory polymers: Concepts of (supra)molecular architecturing

“…Radjabian et al [52] used spun PLA filament, wound in helical form, for SM testing. The filament itself has a complex processing-induced supramolecular structure which does not change in the SM cycle.…”

Shape memory effect and mechanical properties of cyanate ester-polybutadiene epoxy copolymer

“…In addition, several scholars [22][23][24][25] have developed a series of models that can describe the mechanical performance of shape memory effect. For example, the mechanical viscoelastic model can be used to describe the shape memory performance of SMP; we can also use the evaluation method of shape memory alloys [26] to evaluate the shape memory behavior of SMP.…”

Pattern Transformation of Heat-Shrinkable Polymer by Three-Dimensional (3D) Printing Technique

“…2 (see Supplementary Movie 3), the folded lattice was stable in room temperature, but can spread out immediately when plunged into the hot water again, exhibiting a typical characteristic of shape-memory effect. The shape-memory effect of PLA material has been reported in many previous literatures19282930. Therefore, the 3D-printed polymer, which presents a shape-memory effect, displays a heat-shrinkable characteristic and dramatical pattern transformation when heating.…”