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.

scholarly journals Investigation on compatibility of PLA/PBAT blends modified by epoxy-terminated branched polymers through chemical micro-crosslinking

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 39-54 ◽  
Author(s):  
Bo Wang ◽  
Yujuan Jin ◽  
Kai’er Kang ◽  
Nan Yang ◽  
Yunxuan Weng ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Glass Transition ◽  
Sem Analysis ◽  
Branched Polymers ◽  
Poly Lactic Acid ◽  
Elongation At Break ◽  
Butylene Terephthalate ◽  
The Difference ◽  
Physical And Chemical ◽  
The Impact

AbstractIn this study, a type of epoxy-terminated branched polymer (ETBP) was used as an interface compati- bilizer to modify the poly lactic acid (PLA)/poly(butylene adipate-co-butylene terephthalate) (PBAT) (70/30) blends. Upon addition of ETBP, the difference in glass transition temperature between PLA and PBAT became smaller. By adding 3.0 phr of ETBP, the elongation at break of the PLA/PBAT blends was found increased from 45.8% to 272.0%; the impact strength increased from 26.2 kJ·m−2 to 45.3 kJ·m−2. In SEM analysis, it was observed that the size of the dispersed PBAT particle decreased with the increasing of ETBP content. These results indicated that the compatibility between PLA and PBAT can be effectively enhanced by using ETBP as the modifier. The modification mechanism was discussed in detail. It proposes that both physical and chemical micro-crosslinking were formed, the latter of which was confirmed by gel content analysis.

scholarly journals Advanced Infill Designs for 3D Printed Shape-Memory Components

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1225
Author(s):  
Daniel Koske ◽  
Andrea Ehrmann
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Fused Deposition Modeling ◽  
Shape Memory Polymer ◽  
The Other ◽  
Poly Lactic Acid ◽  
Fused Deposition ◽  
Other Hand

Poly(lactic acid) (PLA) is one of the most often used polymers in 3D printing based on the fused deposition modeling (FDM) method. On the other hand, PLA is also a shape memory polymer (SMP) with a relatively low glass transition temperature of ~60 °C, depending on the exact material composition. This enables, on the one hand, so-called 4D printing, i.e., printing flat objects which are deformed afterwards by heating them above the glass transition temperature, shaping them and cooling them down in the desired shape. On the other hand, objects from PLA which have been erroneously deformed, e.g., bumpers during an accident, can recover their original shape to a certain amount, depending on the applied temperature, the number of deformation cycles, and especially on the number of broken connections inside the object. Here, we report on an extension of a previous study, investigating optimized infill designs which avoid breaking in 3-point bending tests and thus allow for multiple repeated destruction and recovery cycles with only a small loss in maximum force at a certain deflection.

scholarly journals Thermal and Dynamic Mechanical Analyses of Poly(Lactic Acid)/Poly(Ethylene Glycol) Blends

2018 ◽  
Vol 1 (1) ◽  
pp. 526-535
Author(s):  
Benaniba Mohamed Tahar ◽  
Aouachria Kamira
Keyword(s):  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ethylene Glycol ◽  
Poly Lactic Acid ◽  
Poly Ethylene Glycol ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Poly Ethylene

Blends of poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) with various contents (0, 5, 10, 15, 20 and 30 weight %) and with different molecular weights (M¯w = 1000, 4000 and 6000 g/mol), called respectively PEG1, PEG2, and PEG3 were prepared by melt blending. Since glass transition temperature (Tg), T? and loss factor (tan ?) are relevant indicators of polymer chain mobility, plasticization has been studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Low molecular weight (LMW) PEG enable increased miscibility with PLA and more efficient reduction of glass transition temperature (Tg) for concentrations of PEG less than 20%. This effect is not only enhanced by the LMW but also by increasing its content up to 20%. As expected, both T? and Tg decrease when increasing PEG molar mass and content up to 20%, which demonstrates the effectiveness of PEG to act as a plasticizer of PLA.

scholarly journals Voltammetric pH Measurements in Unadulterated Foodstuffs, Urine, and Serum with 3D-Printed Graphene/poly(lactic Acid) Electrodes

2020 ◽  
Author(s):  
Fakher M. Rabboh ◽  
Glen O'Neil
Keyword(s):  
Lactic Acid ◽  
Excellent Agreement ◽  
Alkali Metals ◽  
Reaction Rates ◽  
Poly Lactic Acid ◽  
Ph Measurements ◽  
Wide Range ◽  
3D Printed ◽  
Glass Ph Electrode ◽  
The Impact

The pH of a system is a critical descriptor of its chemistry – impacting reaction rates, solubility, chemical speciation, and homeostasis. As a result, pH is one of the most commonly measured parameters in food safety, clinical, and environmental laboratories. Glass pH probes are the gold standard for pH measurements, but suffer drawbacks including frequent recalibration, wet storage of the glass membrane, difficulty in miniaturization, and interferences from alkali metals. In this work, we describe a voltammetric pH sensor that uses a 3D-printed graphene/poly(lactic acid) filament electrode that is pretreated to introduce quinone functional groups to the graphene surface. After thoroughly characterizing the pretreatment parameters using outer-sphere and inner-sphere redox couples, we measured pH by reducing the surface-bound quinones, which undergo a pH-dependent 2e<sup>–</sup>/2H<sup>+</sup> reduction. The position of the redox peak was found to shift –60 ± 2 mV pH<sup>-1</sup> at 25 ºC, which is in excellent agreement with the theoretical value predicted by the Nernst Equation (–59.2 mV pH<sup>-1</sup>). Importantly, the sensors did not require the removal of dissolved oxygen prior to successful pH measurements. We investigated the impact of common interfering species (Pb<sup>2+</sup> and Cu<sup>2+</sup>) and found that there was no impact on the measured pH. We subsequently challenged the sensors to measure the pH of unadulterated complex samples including cola, vinegar, serum, and urine, and obtained excellent agreement compared to a glass pH electrode. In addition to the positive analytical characteristics, the sensors are extremely cheap and easy to fabricate, making them highly accessible to a wide range of researchers. These results pave the way for customizable pH sensors that can be fabricated in (nearly) any geometry for targeted applications using 3D-printing.

Manufacturing of Single Poly(Lactic Acid) Composites

2006 ◽  
Author(s):  
Ruihua Li ◽  
Donggang Yao
Keyword(s):  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Amorphous Film ◽  
Poly Lactic Acid ◽  
Good Adhesion ◽  
Amorphous Films ◽  
Hot Compaction ◽  
Compaction Method ◽  
Tearing Strength

An approach of utilizing slowly crystallizing dynamics for fabrication of poly(lactic acid) (PLA) single-polymer composites (SPCs) was investigated. As a slowly crystallizing polymer, PLA can be prepared as two distinct physical forms, amorphous (or near-amorphous) PLA and highly crystalline PLA. In this study, near-amorphous PLA films and highly crystalline PLA fibers were combined to form a SPC using a rapid hot compaction method at a temperature about 40°C below PLA's melting temperature. It was found that, by rapidly heating an amorphous-crystalline lamination above PLA's glass transition temperature during manufacturing, amorphous films can be fused and good adhesion between the amorphous film and the crystalline fiber can be achieved. Mechanical testing showed that the tearing strength of the SPC is almost half an order higher that that of the original PLA film.

scholarly journals Biocomposites based on poly(lactic acid) and kenaf fibers: Effect of micro-fibrillated cellulose

2013 ◽  
Vol 32 (1) ◽  
pp. 331 ◽  
Author(s):  
Gordana Bogoeva-Gaceva ◽  
Dimko Dimeski ◽  
Vineta Srebrenkoska
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Strength ◽  
Microfibrillated Cellulose ◽  
Poly Lactic Acid ◽  
Kenaf Fiber ◽  
Kenaf Fibers

In this work, the influence of microfibrillated cellulose (MFC) on the basic mechanical properties of PLA/kenaf fiber biocomposites has been studied. The addition of 5–15 % microfibrillated cellulose to a biocomposite premix has resulted in an increased glass transition temperature of the final product, produced by compression molding of previously melt-mixed composite components. The presence of MFC has influenced the interface-sensitive properties of the PLA/kenaf composite: at an optimal loading of 10 %, the interfacial energy release rate was increased by about 20 %. Moreover, flexural strength and modulus of the composites were also improved (from 34.8 MPa to 57.1 MPa and from 4.9 GPa to 5.8 GPa, respectively).   

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