Thermal Characterization of Polyhydroxyalkanoates and Poly(lactic acid) Blends Obtained by Injection Molding

Polylactic acid (PLA) is one of the most commonly used materials for fused deposition modeling (FDM) due to its low cost, biocompatibility, and desirable printing characteristics. However, its low ductility is a major disadvantage for engineering applications where high damage tolerance is needed. This study investigates the feasibility of polyhydroxyalkanoate (PHA) additions to PLA for improving the ductility of parts produced by FDM. Thermal and mechanical behavior of PLA/PHA specimens containing 12 wt % PHA is investigated for a range of printing nozzle temperatures. All PLA/PHA specimens exhibit amorphous PLA phase with semicrystalline PHA and possess outstanding ductility exceeding 160% for nozzle temperatures in the range of 200 C-240 C. Lower and higher nozzle temperatures result in low ductility, similar to that of pure PLA. Overall, PLA/PHA is a very promising polymer blend for FDM processes, providing a combination of sufficient strength with excellent damage tolerance.

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“…, the miscibility is low (but not zero). Loureiro et al . observed a similar decrease in T g upon PHA additions to PLA.…”

Section: Resultsmentioning

confidence: 62%

“…For PLA/PHA specimens, the first glass transition ( T g1 ) measured at around 0 °C corresponds to that of PHA and the second transition ( T g2 ) at around 55 °C corresponds to that of PLA . T g of PLA and PHA can depend on processing conditions, thermal history, and the extent of crystallization .…”

Section: Resultsmentioning

confidence: 99%

Improving the ductility of polylactic acid parts produced by fused deposition modeling through polyhydroxyalkanoate additions

Kaygusuz

Özerinç

2019

J of Applied Polymer Sci

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“…In addition, it was clearly observed that T g of the PLA phase in the blend fibers shifted to a lower temperatures (52–57 °C) than that of neat PLA. A possible explanation for this might be that the molecular chain segments of the P3HB4HB amorphous phase with larger activity accelerated the unfreezing of molecular chain segments of the PLA amorphous phase at lower temperatures, so that T g of the PLA phase in the blend fibers exhibited a decreasing trend with the addition of P3HB4HB …”

Section: Resultsmentioning

confidence: 99%

“…The degrees of crystallinity (X c,fiber ) of neat P3HB4HB, PLA, and the P3HB4HB/PLA blend fibers, were calculated from the enthalpy of fusion according to the following eq. :

X_{normalc, fiber} = \frac{∆ H_{m}}{∆ H_{normalm, normalP 3 HB 4 HB}^{100 %} ∙ W_{normalP 3 HB 4 HB} + ∆ H_{normalm, PLA}^{100 %} ∙ W_{PLA}} \times 100 %,

where ∆ H m is the enthalpy of fusion of the blend fibers, and

∆ H_{normalm, normalP 3 HB 4 HB}^{100 %}

and

∆ H_{normalm, PLA}^{100 %}

are the theoretical enthalpies of fusion for 100% crystalline P3HB4HB and PLA, respectively. W P3HB4HB and W PLA are the weight fractions of P3HB4HB and PLA in the blend fibers, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Polyhydroxyalkanoates (PHAs), which have gained considerable interests inacademic research and industrial manufacturing, which are biosynthesized by various kinds of microorganisms as intracellular carbon sources and energy storage, owing to their complete biodegradability, biocompatibility, and bioresource‐based origins . PHAs will completely degrade into nontoxic by‐products(CO 2 and H 2 O) after being discarded in the natural environment .…”

Section: Introductionmentioning

confidence: 99%

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Novel bioresource‐based poly(3‐Hydroxybutyrate‐co‐4‐Hydroxybutyrate)/poly(LacticAcid) blend fibers with high strength and toughness via melt‐spinning

Chen

Zhao

Hong

et al. 2020

J of Applied Polymer Sci

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Novel biodegradable blend fibers based on the biomaterials poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) and poly(lacticacid) (PLA) were successfully prepared by combining melt spinning and hot drawing. The results showed that the commixture could continuous and stable spin for a P3HB4HB ratio of 30-35 wt% and winding speed of 20-30 m/min. The thermal stability of the P3HB4HB/PLA blend fiber was increased, as determined by thermogravimetric analysis. The crystallinity degree of the P3HB4HB/ PLA blend fibers increased with increasing the P3HB4HB content. The addition of PLA resulted in a low cold crystallization temperature and diminutive size of the lamellar stacks, which would be favorable for the enhancement of the mechanical properties of the blend fiber, when the P3HB4HB content was 30-35 wt%. The P3HB4HB/PLA composite fiber was one type of high-strength and hightoughness fiber, with 1 GPa breaking stress and over 80% strain at break.

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Blown film extrusion of poly(lactic)acid/poly(3‐hydroxybutyrate‐4‐hydroxybutyrate) blends for improved toughness and processability

Koca

Aversa

Barletta

2023

Polymer Engineering & Sci

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Poly(lactic acid) is one of the most commonly used bioplastics thanks to its mechanical performance and low environmental impact. Strategies to overcome excessive rigidity of PLA are constantly investigated. Poor viscoelastic behavior and brittleness of PLA seriously limit its potential application as a common film material. Herein highly amorphous Poly(3‐hydroxybutyrate‐4‐hydroxybutyrate) (P(3HB)(4HB)) was introduced to improve toughness and reduce brittleness of PLA. Anti‐blocking (silica) and anti‐slipping agent (Ethylene bis‐stearamide (EBS)) were added to improve the processability of the blends, specifically to solve winding issues of the blown film and unfolding of the layflat. In this study three formulations containing PLA and different ratios of P(3HB)(4HB), specifically 10–20–30% were extruded. The mechanical, thermal and surface characterization of the films was performed. The tensile and the tear strength test results show that P(3HB)(4HB) increased the ductility of PLA based films. Increasing amounts of P(3HB)(4HB) provide a toughening effect on PLA/P(3HB)(4HB) blown films without altering transparency of PLA. Moreover, the processing additives proved to be efficient in improving film blowing stability and avoiding tackiness during the winding phase of the film.

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Thermal Characterization of Polyhydroxyalkanoates and Poly(lactic acid) Blends Obtained by Injection Molding

Cited by 15 publications

References 14 publications

Improving the ductility of polylactic acid parts produced by fused deposition modeling through polyhydroxyalkanoate additions

Improving the ductility of polylactic acid parts produced by fused deposition modeling through polyhydroxyalkanoate additions

Novel bioresource‐based poly(3‐Hydroxybutyrate‐co‐4‐Hydroxybutyrate)/poly(LacticAcid) blend fibers with high strength and toughness via melt‐spinning

Blown film extrusion of poly(lactic)acid/poly(3‐hydroxybutyrate‐4‐hydroxybutyrate) blends for improved toughness and processability

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