scholarly journals Development of Injection-Molded Polylactide Pieces with High Toughness by the Addition of Lactic Acid Oligomer and Characterization of Their Shape Memory Behavior

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2099 ◽  
Author(s):  
Diego Lascano ◽  
Giovanni Moraga ◽  
Juan Ivorra-Martinez ◽  
Sandra Rojas-Lema ◽  
Sergio Torres-Giner ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Shape Memory ◽  
Percentage Increase ◽  
Shape Memory Behavior ◽  
Memory Recovery ◽  
Injection Molded ◽  
Flexural Tests ◽  
The Impact ◽  
Nucleating Effect

This work reports the effect of the addition of an oligomer of lactic acid (OLA), in the 5–20 wt% range, on the processing and properties of polylactide (PLA) pieces prepared by injection molding. The obtained results suggested that the here-tested OLA mainly performs as an impact modifier for PLA, showing a percentage increase in the impact strength of approximately 171% for the injection-molded pieces containing 15 wt% OLA. A slight plasticization was observed by the decrease of the glass transition temperature (Tg) of PLA of up to 12.5 °C. The OLA addition also promoted a reduction of the cold crystallization temperature (Tcc) of more than 10 °C due to an increased motion of the biopolymer chains and the potential nucleating effect of the short oligomer chains. Moreover, the shape memory behavior of the PLA samples was characterized by flexural tests with different deformation angles, that is, 15°, 30°, 60°, and 90°. The obtained results confirmed the extraordinary effect of OLA on the shape memory recovery (Rr) of PLA, which increased linearly as the OLA loading increased. In particular, the OLA-containing PLA samples were able to successfully recover over 95% of their original shape for low deformation angles, while they still reached nearly 70% of recovery for the highest angles. Therefore, the present OLA can be successfully used as a novel additive to improve the toughness and shape memory behavior of compostable packaging articles based on PLA in the new frame of the Circular Economy.

Aroma profile and lactic acid bacteria characteristic of traditional Slovak cheese “May bryndza”

2021 ◽  
pp. 108201322110399
Author(s):  
Jana Štefániková ◽  
Július Árvay ◽  
Simona Kunová ◽  
Przemysław Łukasz Kowalczewski ◽  
Miroslava Kačániová
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Butanoic Acid ◽  
Aroma Profile ◽  
Volatile Organic ◽  
Ewe's Milk ◽  
The Impact

This paper describes the results of the characterization of a traditional Slovak cheese called “May bryndza” with regard to the profiles of volatile organic compounds and lactic acid bacteria. Samples of “May bryndza“ cheese produced solely from unpasteurized ewe's milk were collected from 4 different Slovak farms, and samples of the cheese produced from a mixture of 2 types of milk (raw ewe's and pasteurized cow's milk) were collected from 3 different Slovak industrial dairies. There were 15 compounds detected and identified by the electronic nose. The impact of the kind of milk and the kind of dairy on the aroma profile of the product was not confirmed by PCA. The compounds with the highest relative contents in samples were acetoin (2.59%–24.55%), acetic acid (6.69%–13.39%), methoxy-phenyl-oxime (4.49%–8.52%), butanoic acid (1.89%–5.67%), and 2,3-butanediol (0.98%–4.08%), which were determined with gas chromatography. A total of 1533 isolates of LAB were obtained from the “May bryndza” cheese samples. Four families, five genera, and 19 species were identified with mass spectrometry, and isolated bacteria, both from the farm and industry dairies were the most frequently found to belong to Lactococcus lactis subsp. lactis.

scholarly journals Shape-Memory Properties of 3D Printed Cubes from Diverse PLA Materials with Different Post-Treatments

Technologies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 71
Author(s):  
Guido Ehrmann ◽  
Bennet Brockhagen ◽  
Andrea Ehrmann
Keyword(s):  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Shape Memory ◽  
Poly Lactic Acid ◽  
Safety Equipment ◽  
Shape Memory Properties ◽  
3D Printed ◽  
Proper Material ◽  
The Impact

Poly(lactic acid) (PLA) belongs to the 3D printable materials which show shape-memory properties, i.e., which can recover their original shape after a deformation if they are heated above the glass transition temperature. This makes PLA quite an interesting material for diverse applications, such as bumpers, safety equipment for sports, etc. After investigating the influence of the infill design and degree, as well as the pressure orientation on the recovery properties of 3D printed PLA cubes in previous studies, here we report on differences between different PLA materials as well as on the impact of post-treatments after 3D printing by solvents or by heat. Our results show not only large differences between materials from different producers, but also a material-dependent impact of the post treatments. Generally, it is possible to tailor the mechanical and recovery properties of 3D printed PLA parts by choosing the proper material in combination with a chemical or temperature post-treatment.

Effects of Processing Parameters and Nanofillers on Mechanical and Thermal Properties and Morphology of Impact Modified Poly (lactic acid)

2013 ◽  
Vol 1499 ◽  
Author(s):  
Eda Acik ◽  
Ulku Yilmazer
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Thermal Properties ◽  
Impact Strength ◽  
Random Copolymer ◽  
Processing Parameters ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Injection Molded ◽  
The Impact

ABSTRACTTernary nanocomposites of poly (lactic acid) (PLA) were produced by melt blending with two types of elastomers and five types of organoclays to obtain improved mechanical properties such as tensile strength, modulus and impact strength. One of the elastomers is a random copolymer of ethylene and glycidyl methacrylate (E-GMA) and the other one is a random terpolymer of ethylene-butyl acrylate-maleic anhydride (E-BA-MAH). Organically modified montmorillonites (OMMT) were utilized as nanofillers. XRD, DSC, tensile and impact tests were done on the injection molded samples. FTIR, SEM and TEM analyses are still in progress. As preliminary results, thermal analysis showed that the addition of compatibilizers and organoclays does not have a distinct effect on the thermal properties of the composites, and no evidence of nucleation activity of compatibilizers or organoclays was found. For all types of organoclays, the nanocomposites produced with E-GMA exhibited better mechanical properties in comparison to nanocomposites containing E-BA-MAH, especially for the impact strength.

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