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.

Isothermal Crystallization Behavior of Poly (L-lactic Acid)/ Surface-Grafted Silica Nanocomposites

2012 ◽  
Vol 268-270 ◽  
pp. 37-40 ◽  
Author(s):  
Yan Hua Cai
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Melt Blending ◽  
Scanning Calorimetry ◽  
Silica Nanocomposites ◽  
Induction Periods ◽  
Sio2 Nanocomposites ◽  
Different Content

The Poly(L-lactic acid)(PLLA)/surface-grafting silica(g-SiO2) nanocomposites were prepared by melt blending. The isothermal crystallization behavior of PLLA/g-SiO2 nanocomposites with different content of g-SiO2 was investigated by optical depolarizer. In isothermal crystallization from melt, the induction periods and half times for overall PLLA crystallization (95°C Tc 120°C) were affected by the crystallization temperature and the content of g-SiO2 in nanocomposites. The results showed that g-SiO2 as a kind of heterogeneous nucleating agent can reduce induction periods and half times for overall PLLA crystallization. The thermal properties of PLLA/g-SiO2 samples were also investigated by differential scanning calorimetry (DSC), The results showed that the crystalline degree of PLLA was improved as the presence of g-SiO2.

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.

Poly(lactic acid)/Graphene Nanocomposites Prepared via Solution Blending Using Chloroform as a Mutual Solvent

2011 ◽  
Vol 11 (9) ◽  
pp. 7813-7819 ◽  
Author(s):  
Yanhua Chen ◽  
Xiayin Yao ◽  
Xufeng Zhou ◽  
Zhijuan Pan ◽  
Qun Gu
Keyword(s):  
Lactic Acid ◽  
Poly Lactic Acid ◽  
Graphene Nanocomposites ◽  
Solution Blending

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.

Biodegradable Composite Materials Based on Poly(3-Hydroxybutyrate) for 3D Printing Applications

2019 ◽  
Vol 955 ◽  
pp. 56-61
Author(s):  
Premysl Mencik ◽  
Veronika Melcova ◽  
Sona Kontarova ◽  
Radek Prikryl ◽  
Dagmara Perdochova ◽  
...  
Keyword(s):  
Lactic Acid ◽  
3D Printing ◽  
Cross Sections ◽  
Optical Microscope ◽  
Zinc Stearate ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Biodegradable Composite ◽  
Base Polymer

Presented work deals with the development of bio-source and biodegradable composite material for 3D printing. Polymer blend based on poly (3-hydroxybutyrate) (60 wt%) and poly (lactic acid) (25 wt%) plasticized by tributyl citrate (15 wt%) was used as a matrix. This base blend was filled with 10 vol% of kaolin or limestone. Zinc stearate was used for the surface treatment of the limestone samples. The mechanical and thermal properties of the composites, as well as their behavior during 3D printing process, were compared with unfilled blend and commercial poly (lactic acid) based 3D printing filament. Warping behavior, one of the main problems of 3D printing materials, was studied by means of warp coefficient. Cross-sections of specimens 3D printed under the same processing conditions were observed by the optical microscope. In the case of composite samples, individual filaments were separated. Despite the separation, composites filled with kaolin and with surface treated limestone exhibited satisfying mechanical properties. Scanning electron microscopy analysis confirmed good particle distribution of the samples with kaolin and surface treated limestone. No significant particle agglomerates were formed in the composites with limestone proving good dispergation ability of zinc stearate. Thermogravimetric analysis and Differential scanning calorimetry analysis showed no degradable effect of the used fillers on base polymer matrix. Observed results indicate that kaolin and surface treated limestone are suitable fillers for the bio-source composites used for 3D printing.

scholarly journals Composites Based on Poly(Lactic Acid) (PLA) and SBA-15: Effect of Mesoporous Silica on Thermal Stability and on Isothermal Crystallization from Either Glass or Molten State

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2743
Author(s):  
Tamara M. Díez-Rodríguez ◽  
Enrique Blázquez-Blázquez ◽  
Ernesto Pérez ◽  
María L. Cerrada
Keyword(s):  
Lactic Acid ◽  
Mesoporous Silica ◽  
Isothermal Crystallization ◽  
Physical Aging ◽  
Glassy State ◽  
Poly Lactic Acid ◽  
Molten State ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

Several composites based on an L-rich poly(lactic acid) (PLA) with different contents of mesoporous Santa Barbara Amorphous (SBA-15) silica were prepared in order to evaluate the effect of the mesoporous silica on the resultant PLA materials by examining morphological aspects, changes in PLA phases and their transitions, and, primarily, the influence on some final properties. Melt extrusion was chosen for the obtainment of the composites, followed by quenching from the melt to prepare films. Completely amorphous samples were then attained, as deduced from X-ray diffraction and differential scanning calorimetry (DSC) analyses. Thermogravimetric analysis (TGA) results demonstrated that the presence of SBA-15 particles in the PLA matrix did not exert any significant influence on the thermal decomposition of these composites. An important nucleation effect of the silica was found in PLA, especially under isothermal crystallization either from the melt or from its glassy state. As expected, isothermal crystallization from the glass was considerably faster than from the molten state, and these high differences were also responsible for a more considerable nucleating role of SBA-15 when crystallizing from the melt. It is remarkable that the PLA under analysis showed very close temperatures for cold crystallization and its subsequent melting. Moreover, the type of developed polymorphs did not accomplish the common rules previously described in the literature. Thus, all the isothermal experiments led to exclusive formation of the α modification, and the observation of the α’ crystals required the annealing for long times at temperatures below 80 °C, as ascertained by both DSC and X-ray diffraction experiments. Finally, microhardness (MH) measurements indicated a competition between the PLA physical aging and the silica reinforcement effect in the as-processed amorphous films. Physical aging in the neat PLA was much more important than in the PLA matrix that constituted the composites. Accordingly, the MH trend with SBA-15 content was strongly dependent on aging times.

Thermal behavior of modified poly(L-lactic acid): effect of aromatic multiamide derivative based on 1H-benzotriazole

e-Polymers ◽  
2016 ◽  
Vol 16 (4) ◽  
pp. 303-311 ◽  
Author(s):  
Yan-Hua Cai ◽  
Li-Sha Zhao
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Melting Behavior ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Onset Crystallization Temperature

AbstractThe goal of this work was to synthesis a novel aromatic multiamide derivative based on 1H-benzotriazole (PB) as an organic nucleating agent for poly(L-lactic acid) (PLLA), and investigate the effect of PB on the non-isothermal crystallization, melting behavior and thermal decomposition of PLLA. Here, PB was firstly synthesized through 1H-benzotriazole aceto-hydrazide and terephthaloyl chloride, then PB-nucleated PLLA was fabricated via melt-blending technology at various PB concentration from 0.5 wt% to 3 wt%. Finally, the thermal performances were evaluated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The high thermal decomposition temperature of PB indicated that PB possessed possibility as a nucleating agent for PLLA, and the non-isothermal crystallization behavior confirmed the crystallization accelerating effectiveness of PB for PLLA. Upon optimum concentration of 2 wt%, the onset crystallization temperature, the crystallization peak temperature and the non-isothermal crystallization enthalpy increased from 101.4°C, 94.5°C and 0.1 J·g-1 to 121.3°C, 115.8°C and 35.1 J·g-1, respectively. In addition, the non-isothermal crystallization behavior was also affected by the cooling rate and the final melting temperature. The melting behavior further evidenced the advanced nucleating ability of PB, and the competitive relationship between PB and the heating rate, the nuclear rate and crystal growth rate. Thermal stability measurement showed that PB with a concentration of 1 wt%–2 wt% could slightly improve the thermal stability of PLLA.

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