scholarly journals Bio-composites for Fused Filament Fabrication. Effects of Maleic Anhydride Grafting on Poly(Lactic Acid) and Microcellulose

2021 ◽  
Author(s):  
Daniele Rigotti ◽  
Luca Fambri ◽  
Alessandro Pegoretti
Keyword(s):  
Lactic Acid ◽  
Maleic Anhydride ◽  
Nucleating Agent ◽  
Mechanical Analysis ◽  
Poly Lactic Acid ◽  
Crystalline Cellulose ◽  
Fused Filament Fabrication ◽  
Scanning Calorimetry ◽  
Electron Microscopy Analysis ◽  
Reactive Mixing

Abstract Composite filaments consisting of poly(lactic acid) (PLA) and micro crystalline cellulose (MCC) were successfully used for additive manufacturing (AM) by fused filament fabrication (FFF). PLA and MCC bio-composites were obtained by direct mixing in a melt compounder; maleic anhydride (MAH) was also grafted onto PLA in reactive mixing stage to evaluate its effect on the final properties of the printed material. Filaments with various concentrations of MCC (up to a maximum content of 10 wt%) were produced with a single screw extruder and used to feed a commercial desktop FFF printer. Upon grafting of PLA with MAH, a more coherent interfacial morphology between PLA and MCC was detected by electron microscopy analysis. The thermal degradation of the PLA was unaffected by the presence of MCC and MAH. According to differential scanning calorimetry and dynamic mechanical analysis results, micro-cellulose acted as nucleating agent for PLA. In fact, the crystallization peak shifted towards lowers temperature and a synergistic effect when MCC was added to PLA grafted with MAH was observed possibly due to the increase of the chain mobility. Micro cellulose led to an increase in the stiffness of the material in both filaments and 3D printed specimen, however, a different fracture behavior was observed due to the peculiar structure of printed samples.

scholarly journals Influence of the Lignin Content on the Properties of Poly(Lactic Acid)/lignin-Containing Cellulose Nanofibrils Composite Films

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1013 ◽  
Author(s):  
Xuan Wang ◽  
Yuan Jia ◽  
Zhen Liu ◽  
Jiaojiao Miao
Keyword(s):  
Lactic Acid ◽  
Lignin Content ◽  
Cellulose Nanofibrils ◽  
Composite Films ◽  
Tensile Tests ◽  
Nucleating Agent ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry

Poly(lactic acid) (PLA)/lignin-containing cellulose nanofibrils (L-CNFs) composite films with different lignin contents were produced bythe solution casting method. The effect of the lignin content on the mechanical, thermal, and crystallinity properties, and PLA/LCNFs interfacial adhesion wereinvestigated by tensile tests, thermogravimetric analysis, differential scanning calorimetry (DSC), dynamic mechanical analysis, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The tensile strength and modulus of the PLA/9-LCNFs (9 wt % lignin LCNFs) composites are 37% and 61% higher than those of pure PLA, respectively. The glass transition temperature (Tg) decreases from 61.2 for pure PLA to 52.6 °C for the PLA/14-LCNFs (14 wt % lignin LCNFs) composite, and the composites have higher thermal stability below 380 °C than pure PLA. The DSC results indicate that the LCNFs, containing different lignin contents, act as a nucleating agent to increase the degree of crystallinity of PLA. The effect of the LCNFs lignin content on the PLA/LCNFs compatibility/adhesion was confirmed by the FTIR, SEM, and Tg results. Increasing the LCNFs lignin content increases the storage modulus of the PLA/LCNFs composites to a maximum for the PLA/9-LCNFs composite. This study shows that the lignin content has a considerable effect on the strength and flexibility of PLA/LCNFs composites.

Crystallization Properties of Nucleated Poly(lactic acid)

2012 ◽  
Vol 549 ◽  
pp. 322-326 ◽  
Author(s):  
Yong Chen ◽  
Qiang Dou
Keyword(s):  
Lactic Acid ◽  
Crystallization Behavior ◽  
Polarized Light ◽  
Nucleating Agent ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystallization Properties ◽  
Melting And Crystallization

The effect of a nucleating agent (NT-C) on the crystallization behavior of poly(lactic acid) (PLA) was studied. The melting and crystallization behavior and spherulitic morphology of the nucleated PLA were investigated by means of differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarized light microscopy (PLM). It is found that the crystallization temperature and crystallinity increase, the spherulitic size decrease for the nucleated PLA. But the crystal structure of the nucleated PLA is not changed.

Crystallization and Thermal Degradation of Green Nanocomposites Based on Lignin Coated Cellulose Nanocrystals and Poly(Lactic Acid)

2017 ◽  
Vol 737 ◽  
pp. 256-261 ◽  
Author(s):  
Martin Boruvka ◽  
Luboš Bĕhálek
Keyword(s):  
Lactic Acid ◽  
Cellulose Nanocrystals ◽  
Raw Material ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Crystalline Cellulose ◽  
Melt Crystallization ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Twin Screw

Cellulose is almost inexhaustible source of raw material comprising at least one-third of all biomass matter. Through deconstruction of cellulose hierarchical structure can be extracted highly crystalline cellulose nanocrystals (CNC) with impressive properties. However, the main barrier in the processing of the nanocomposites based on CNC is their inhomogeneous dispersion and distribution in the non-polar polymer matrix. In this paper is this problem addressed by use of novel hydrophobic lignin coated CNC as a biobased nucleation agents in poly (lactic acid) (PLA) nanocomposites. These green nanocomposites based on natural plant derived substances have enormous potential to replace materials originated from non-renewable resources and show promise of providing degradation back into the environment when they are no longer needed. Resulted composites prepared by twin screw extrusion and injection moulding were characterized by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of L-CNC (1, 2 and 3 wt. %) into PLA increased melt crystallization enthalpy and decreases the cold crystallization enthalpy. The degree of crystallinity (cc) increased from 5.6 % (virgin PLA) to 8.5 % (PLA/1-L-CNC), 10.3 % (PLA/2-L-CNC) and 10.7 % (PLA/3-L-CNC). The wide range of degradation temperatures of lignin coating has been observed starting at 100 °C.

Structure and properties of poly(lactic acid)/poly(lactic acid)-α-cyclodextrin inclusion compound composites

2017 ◽  
Vol 37 (9) ◽  
pp. 897-909
Author(s):  
Li Zhang ◽  
Weijun Zhen ◽  
Yufang Zhou
Keyword(s):  
Lactic Acid ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Mechanical Analysis ◽  
Poly Lactic Acid ◽  
Polymerization Temperature ◽  
Scanning Calorimetry ◽  
Synthesis Conditions ◽  
Cyclodextrin Inclusion ◽  
Comprehensive Performance

Abstract Poly(lactic acid) (PLA) was synthesized using a green catalyst, nano-zinc oxide (ZnO). The optimum synthesis conditions of PLA were as follows: a stoichiometric amount of 0.5 wt% of nano-ZnO, polymerization time of 14 h, and polymerization temperature of 170°C. Gel permeation chromatography results showed that the weight-average molecular weight (Mw) of PLA was 13,072 g/mol with a polydispersity index (PDI) of 1.7. Furthermore, PLA-α-cyclodextrin inclusion compounds (PLA-CD-ICs) were prepared by ultrasonic co-precipitation techniques. X-ray diffraction analysis and Fourier transform infrared spectroscopy demonstrated the change in lattice of α-CD from a cage configuration to a tunnel structure and the existence of some physical interactions between α-CD and PLA in the PLA-CD-ICs. To enhance the crystallization properties of PLA, PLA/PLA-CD-IC composites were blended with different contents of PLA-CD-ICs as nucleating agents. The crystallization behavior and comprehensive performance were investigated by differential scanning calorimetry, polarized optical microscopy, tensile testing, dynamic mechanical analysis, and scanning electron microscopy. Compared to PLA, the crystallinities of PLA/PLA-CD-IC composites were increased by 24.0%, 26.3%, 27.3%, and 31.8%. The results of all the analyses proved that PLA-CD-ICs were useful as green organic nucleators and improved the comprehensive performance of PLA materials.

Preparation and Isothermal Crystallization Behavior of Poly(lactic acid)/Graphene Nanocomposites

2011 ◽  
Vol 284-286 ◽  
pp. 246-252 ◽  
Author(s):  
Yan Hua Chen ◽  
Xia Yin Yao ◽  
Zhi Juan Pan ◽  
Qun Gu
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Graphene Nanosheets ◽  
Nucleating Agent ◽  
Optical Microscope ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Avrami Model ◽  
Graphene Nanocomposites ◽  
Solution Blending

Poly(lactic acid) (PLA)/graphene nanocomposites were prepared by solution blending using chloroform as a mutual solvent. Transmission electron microscopy (TEM) was used to examine the quality of the dispersion of graphene in the PLA matrix. The isothermal crystallization behaviors of PLA and PLA/graphene nanocomposites were investigated by differential scanning calorimetry (DSC). The isothermal crystallization kinetics were analyzed by Avrami model based on the DSC data. The results showed that the well dispersed graphene nanosheets could act as a heterogeneous nucleating agent and lead to an acceleration of crystallization during the PLA isothermal crystallization process. According to the Arrhenius equation, the activation energies were found to be -106.9 and -46.6 kJ/mol for pure PLA and PLA/0.1 wt % graphene nanocomposite, respectively. The crystal morphology were characterized with polarizing optical microscope (POM).

Non-isothermal crystallization kinetics of poly (lactic acid)/graphene nanocomposites

2013 ◽  
Vol 33 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Yanhua Chen ◽  
Xiayin Yao ◽  
Qun Gu ◽  
Zhijuan Pan
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Graphene Nanocomposites ◽  
Solution Blending ◽  
Transmission Electron ◽  
Graphene Nanocomposite

Abstract Poly(lactic acid) (PLA)/graphene nanocomposites were prepared by solution blending and the dispersibility of graphene in the PLA matrix was examined by transmission electron microscopy (TEM). The non-isothermal crystallization behaviors of pure PLA and PLA/graphene nanocomposites from the melt were investigated by differential scanning calorimetry (DSC). The results showed that the graphene could play a role as a heterogeneous nucleating agent during the non-isothermal crystallizing process of PLA, and accelerate the crystallization rate. The non-isothermal crystallizing data were analyzed with the Avrami, Ozawa and Mo et al. models and the crystallization parameters of the samples were obtained. It is demonstrated that the combination of the Avrami and Ozawa models developed by Mo et al. was successful in describing the non-isothermal crystallization process for pure PLA and its nanocomposite. According to the Kissinger equation, the activation energies were found to be -154.3 and -179.5 kJ/mol for pure PLA and PLA/0.1 wt% graphene nanocomposite, respectively. Furthermore, the spherulite growth behavior was investigated by polarized optical microscopy (POM) and the results also supported the DSC data.

Isothermal Crystallization Behavior and Kinetics of Poly (lactic acid) Filled with a Novel Nucleating Agent

2014 ◽  
Vol 887-888 ◽  
pp. 716-722
Author(s):  
Nai Xu ◽  
Xing Hui Wang ◽  
Li Sha Pan ◽  
Su Juan Pang ◽  
Xuan Chen ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Nucleation Effect ◽  
Amide Derivatives ◽  
Aromatic Amide ◽  
Kinetics Of

The crystallization behavior and crystalline structure of poly (lactic acid) (PLA) filled with a novel nucleating agent (TMC328), which is a kind of aromatic amide derivatives, were investigated using differential scanning calorimetry (DSC) and wide angle X-ray (XRD). In isothermal crystallization from the melt, the present of TMC328 remarkably affected the isothermal crystalline behaviors of PLA. PLA/0.5% TMC328 sample exhibited very short crystallization half-times at 90-130 °C. Furthermore, the Avrami theory was used to describe the isothermal crystallization kinetics of PLA/TMC328 samples. It is confirmed that TMC328 showed a significant heterogeneous nucleation effect on the crystallization of PLA matrix. Moreover, XRD measurement indicates that TMC328 is a kind of α-form nucleating agent for PLA.

Poly(lactic acid) phase transitions in the presence of nano calcium carbonate: Opposing effect of nanofiller on static and dynamic measurements

2018 ◽  
Vol 32 (3) ◽  
pp. 312-327 ◽  
Author(s):  
Omid Yousefzade ◽  
Javad Jeddi ◽  
Elham Vazirinasab ◽  
Hamid Garmabi
Keyword(s):  
Lactic Acid ◽  
Glass Transition ◽  
Calcium Carbonate ◽  
Mechanical Analysis ◽  
Polymer Chains ◽  
Poly Lactic Acid ◽  
Modulated Dsc ◽  
Scanning Calorimetry ◽  
Chain Mobility ◽  
Dispersion State

The effect of stearic acid-coated nano calcium carbonate (NCC) on transitions and chain mobility of poly(lactic acid) (PLA) was investigated. Dispersion state of NCC in polymeric matrix was explored using scanning electron microscopy and surface tension component measurements. Trends of PLA transitional phenomena were investigated using the results of dynamical mechanical analysis (DMA) and differential scanning calorimetry (DSC) in the nanocomposite systems based on PLA and NCC. In addition, two types of crystal structures and decreasing the glass transition temperature were distinguished using temperature-modulated DSC (TMDSC). Higher melting points of polymer crystals were found in TMDSC experiments due to low and dynamic heating rate compared to the conventional DSC. Dynamics of polymer chains, affected by NCC, were quantified using cooperativity length, ξ α, and the number of relaxing structural units, Nα, in the glass transition region. NCC particles hindered the cooperative motion of polymer chains at glass transitions and crystallization in TMDSC measurements, whereas the DMA results indicated that NCC particles may act as lubricant and simplified chain mobility.

scholarly journals Comparison of the efficiency of the most effective heterogeneous nucleating agents for Poly(lactic acid)

2021 ◽  
Author(s):  
Tatyana Ageyeva ◽  
József Gábor Kovács ◽  
Tamás Tábi
Keyword(s):  
Lactic Acid ◽  
Tensile Modulus ◽  
Charpy Impact ◽  
Nucleating Agent ◽  
Poly Lactic Acid ◽  
Nucleating Agents ◽  
Scanning Calorimetry ◽  
Injection Molded ◽  
Heat Deflection Temperature ◽  
Charpy Impact Strength

AbstractWe selected the thirteen most effective nucleating agents for Poly(lactic acid) (PLA) from the literature, and synthesized and compounded them with two different PLA grades: 3001D (1.4% D-lactide content) and 3100HP (0.5% D-lactide content, considered PLLA). We determined the crystallinity and crystallization of PLA with different nucleating agents in identical conditions (same nucleating agent content, same cooling rate) with the help of differential scanning calorimetry. We compared the efficiency of each nucleating agent and found that for both PLA grades, Zinc PhenylPhosphonate was the most effective. However, even when nucleated PLA was injection molded into a cold mold (25 °C), it still could not fully crystallize during cooling and the heat deflection temperature did not increase significantly. The maximum achieved crystallinity, in this case, was between 32.4 and 35.7%. On the contrary, when a 90 °C “hot mold” and in-mold crystallization together were applied, the specimens achieved full crystallization during the injection molding cycle (crystallinity was between 44.5 and 50.0%), and the heat deflection temperature increased to an average of 88.8 °C. We also examined the mechanical properties of the nucleated PLA and found that the usage of nucleating agents together with a hot mold improved tensile strength, tensile modulus, and Charpy impact strength but decreased elongation at break.

Effect of Poly(D-Lactic Acid)-co-Polyethylene Glycol on the Crystallization of Poly(L-Lactic Acid)

2017 ◽  
Vol 751 ◽  
pp. 283-289 ◽  
Author(s):  
Ployrawee Kaewlamyai ◽  
Amornrat Lertworasirikul
Keyword(s):  
Lactic Acid ◽  
Polyethylene Glycol ◽  
Weight Ratio ◽  
Crystallization Rate ◽  
Heat Stability ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Infrared Spectrometry ◽  
Scanning Calorimetry

Poly (lactic acid) (PLA) is a biopolymer derived from renewable resources and can be disposed of without creating harm to the environment. PLA can be formed by thermoplastic processes and has good mechanical properties. However, its disadvantages are a high crystallization temperature, slow crystallization rate, poor heat stability and low ductility. In the past, it was found that poly (D-lactic acid) (PDLA) can form complexes with poly (L-lactic acid) (PLLA) and the complexes could accelerate the crystallization and increase the degree of crystallinity of the PLA, but decrease the ductility. It is known that polyethylene glycol (PEG) can improve the ductility of PLLA. In this research, PDLA was copolymerized with PEG in an attempt to improve both crystallization behavior and ductility of PLLA. Poly (D-lactic acid)-co-polyethylene glycol (PDEG) was synthesized by ring opening polymerization using D-lactide and PEG at a D-lactide:PEG weight ratio of 10:3. The PDEG was blended with PLLA with a PDEG content of 0wt% to 50wt% by melt blending process. Fourier transform infrared spectrometry (FT-IR) and X-Ray diffractometry (XRD) confirmed the stereocomplex formation between PDEG and PLLA. Characterization by differential scanning calorimetry (DSC) revealed that crystallization temperatures of the blends were decreased in the presence of PDEG. Storage moduli and tan of the blends obtained from dynamic mechanical analysis (DMA) decreased as PDEG content increased. Polarized optical microscopy (POM) micrographs of blends with PDEG content of 1wt% to 5wt% obviously showed that crystallization rate was increased. PDEG has the potential to be an effective nucleating agent and efficient plasticizer for PLLA.

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