“…Therefore, the composites show elasticity instead of viscosity. 30 The η* values for all samples decrease distinctly with increasing the frequency, which indicates that PLA/jute/TOA composites are typical pseudoplastic fluid from Figure 6(c). The values of G 0 , G 00 , and η* of PJ, PT, PJGT5, and PJTT10 are obviously much higher than those of PLA; however, those of PJGT15 become lower.…”
Section: Rheological Behaviorsmentioning
confidence: 75%
“…Therefore, the composites show elasticity instead of viscosity. 30 Figure 6.The curves of (a) storage modulus ( G ′ ); (b) loss modulus ( G ″ ); and (c) complex viscosity ( η *) of pure PLA and PLA/jute/TOA composites.…”
In this work, novel plasticizing biodegradable poly (lactic acid) (PLA) composites were prepared by melt blending of jute and tung oil anhydride (TOA), and the physical and mechanical properties of PLA/jute/TOA composites were tested and characterized. The impact strength of PLA/jute/TOA composites significantly increases with increasing the content of TOA. The SEM images of fracture surface of PLA/jute/TOA composites become rough after the incorporation of TOA. In addition, TOA changes the crystallization temperature and decomposition process of PLA/jute/TOA composites. With increasing the amount of TOA, the value of storage modulus (E′) of PLA/jute/TOA composites gradually increases. The complex viscosity (η*) values for all samples reduce obviously with increasing the frequency, which means that the pure PLA and PLA/jute/TOA composites is typical pseudoplastic fluid. This is attributed to the formation of crosslinking, which restricts the deformation of the composites.
“…Therefore, the composites show elasticity instead of viscosity. 30 The η* values for all samples decrease distinctly with increasing the frequency, which indicates that PLA/jute/TOA composites are typical pseudoplastic fluid from Figure 6(c). The values of G 0 , G 00 , and η* of PJ, PT, PJGT5, and PJTT10 are obviously much higher than those of PLA; however, those of PJGT15 become lower.…”
Section: Rheological Behaviorsmentioning
confidence: 75%
“…Therefore, the composites show elasticity instead of viscosity. 30 Figure 6.The curves of (a) storage modulus ( G ′ ); (b) loss modulus ( G ″ ); and (c) complex viscosity ( η *) of pure PLA and PLA/jute/TOA composites.…”
In this work, novel plasticizing biodegradable poly (lactic acid) (PLA) composites were prepared by melt blending of jute and tung oil anhydride (TOA), and the physical and mechanical properties of PLA/jute/TOA composites were tested and characterized. The impact strength of PLA/jute/TOA composites significantly increases with increasing the content of TOA. The SEM images of fracture surface of PLA/jute/TOA composites become rough after the incorporation of TOA. In addition, TOA changes the crystallization temperature and decomposition process of PLA/jute/TOA composites. With increasing the amount of TOA, the value of storage modulus (E′) of PLA/jute/TOA composites gradually increases. The complex viscosity (η*) values for all samples reduce obviously with increasing the frequency, which means that the pure PLA and PLA/jute/TOA composites is typical pseudoplastic fluid. This is attributed to the formation of crosslinking, which restricts the deformation of the composites.
“…3 . It was obvious that the pure PLA and PLA/PEG (97/3) blends exhibited non-Newtonian “shear-thinning” behaviors, and the complex viscosity of the pure PLA and PLA/PEG blends decreased significantly with increasing shearing rates [ 37 ]. Figure 3 shows that as the temperature increases, the complex viscosity of the pure PLA and PLA/PEG blends decreases.…”
Polylactic acid (PLA) micro/nanofiber fabrics with good biodegradability and biocompatibility have wide applications in the medical protective field. However, the poor flexibility, high brittleness, and insufficient mechanical properties of PLA micro/nanofiber fabrics remain challenging. Herein, a polylactic acid/polyethylene glycol (PLA/PEG) micro/nanofiber fabric with aligned fibers was successfully prepared by an inexpensive and straightforward post-drafting melt blown process. The experimental results showed that PEG can reduce the T
g
of PLA, improve the mobility of PLA molecular chains, reduce the complex viscosity of PLA/PEG blends, and play a role in plasticization. The PLA/PEG micro/nanofiber fabrics had an aligned micro/nanofibrous structure, and the average fiber diameter was easily adjusted from 10.7 to 4.9 μm by tailoring the melt blown process parameters, i.e., die temperature and hot air temperature. Moreover, the breaking tensile strength increased from 45.06 to 78.73 N in the machine direction (MD), while it increased from 11.87 to 21.89 N in the cross direction (CD), which means that the breaking tensile strength was enhanced significantly by adjusting the die temperature and hot air temperature. Furthermore, the prepared samples showed a high softness score of 82.7, a large synthetic blood contact angle of 125.7°, and an excellent bursting strength of 58.5 N. These PLA/PEG micro/nanofiber fabrics with aligned fibers are ideal candidates for medical protective applications such as surgical gowns, protection suits, masks, and medical bandages.
Supplementary Information
The online version contains supplementary material available at 10.1007/s10965-022-03184-2.
“…The stability can also be enhanced by hydrophobic segments that exhibit stronger physical interactions, e.g., block copolymers of PEO with poly(L-lactic acid) (PLLA) or poly[(rac-lactic acid)-co-glycolic acid) (PLGA), which additionally introduce the capability for hydrolytic degradation into the polymer [40,41]. PLGA/PEO-based di-/triblock copolymers, again, depending on molecular weight and the PEO-PLGA ratio [42], can from transparent gels with maintained structural integrity and mechanical strength, which present a sol-gel transition at ~30 • C [43]. Such block polymers have been used for the release of both hydrophilic and hydrophobic drugs, as well as for protein encapsulation [44][45][46][47].…”
Section: Responsiveness To External Stimuli 21 Temperature-responsive...mentioning
Switchable polymeric materials, which can respond to triggering signals through changes in their properties, have become a major research focus for parenteral controlled delivery systems. They may enable externally induced drug release or delivery that is adaptive to in vivo stimuli. Despite the promise of new functionalities using switchable materials, several of these concepts may need to face challenges associated with clinical use. Accordingly, this review provides an overview of various types of switchable polymers responsive to different types of stimuli and addresses opportunities and challenges that may arise from their application in biomedicine.
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