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.

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.

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.

Blending and plasticising effects on the behaviour of poly(lactic acid)/poly(ε-caprolactone)

2018 ◽  
Vol 26 (5-6) ◽  
pp. 337-345 ◽  
Author(s):  
Nesrine Khitas ◽  
Kamira Aouachria ◽  
Mohamed Tahar Benaniba
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Triethyl Citrate ◽  
Acetyl Tributyl Citrate ◽  
The Degree Of Crystallinity

Polymer blending is one of the most convenient methods to be used to overcome the limitations of some single properties of polymers and to achieve the combinations required for specific applications. Another feasible common practice is the incorporation of additives of low molecular weight such as plasticisers to impart flexibility, improve toughness and lower the glass transition temperature ( Tg). This study focused on the effects of blending and plasticising on the crystallisation behaviour of poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL). PCL with longer degradation time compared with other polymers was blended with PLA to overcome the limitation of its brittleness and poor thermal stability. Acetyl tributyl citrate (ATBC) and acetyl triethyl citrate (TEC) were used as plasticiser in PLA/PCL blends. The rigid and plasticised blends at various ratios were analysed by differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The results revealed a slight increase in the degree of crystallinity and a significant increase in the Tg of PLA due to the addition of PCL. The addition of ATBC has promoted a decrease in thermal stability of the blends. The slight increase in the degree of crystallinity suggested that PCL acted as a nucleating agent. The citrate plasticisers were shown to lower the Tg and have much more enhanced the crystallisation of PLA. Moreover, the rigid and plasticised blends were shown to be partially miscible.

scholarly journals Application of Melt-Blown Poly(lactic acid) Fibres in Self-Reinforced Composites

Polymers ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 766 ◽  
Author(s):  
Dániel Vadas ◽  
Dávid Kmetykó ◽  
György Marosi ◽  
Katalin Bocz
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Fold Increase ◽  
Tensile Tests ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Static Tensile ◽  
Micrometer Size ◽  
Nonwoven Mats

The aim of our research was to produce poly(lactic acid) (PLA) fibres with diameters in the micrometer size range, serving as the reinforcing phase in self-reinforced (SR) PLA composites. Nonwoven PLA mats were manufactured by solvent-free melt-blowing technology. Three types of PLA differing in d-lactide content were processed with a productivity as high as 36 g/h. The crystallinity of the PLA microfibres was enhanced by thermal annealing. A 2–3-fold increase in the degree of crystallinity was obtained, as measured by differential scanning calorimetry (DSC). Fibre diameters between 2–14 µm were revealed by scanning electron microscopy (SEM). Static tensile tests were performed on the nonwoven mats, showing the reduced moduli of the annealed fibres due the amorphous relaxation. The PLA mats were processed via the hot compaction technique and formed into SR–PLA composites. The morphological and mechanical properties of the obtained microstructural composites were comprehensively studied. Composites prepared from annealed, thermally more stable PLA nonwoven mats showed superior mechanical properties; the tensile strength improved by 47% due to the higher residual fibre content.

Enhancing the Thermal and Mechanical Characteristics of Polyvinyl Alcohol (PVA)-Hemp Protein Particles (HPP) Composites

2021 ◽  
Vol 36 (2) ◽  
pp. 137-143
Author(s):  
S. A. Awad
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Composite Films ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Solution Casting Method ◽  
Protein Particles

Abstract This paper aims to describe the thermal, mechanical, and surface properties of a PVA/HPP blend whereby the film was prepared using a solution casting method. The improvements in thermal and mechanical properties of HPP-based PVA composites were investigated. The characterization of pure PVA and PVA composite films included tensile tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results of TGA and DSC indicated that the addition of HPP increased the thermal decomposition temperature of the composites. Mechanical properties are significantly improved in PVA/HPP composites. The thermal stability of the PVA composite increased with the increase of HPP filler content. The tensile strength increased from 15.74 ± 0.72 MPa to 27.54 ± 0.45 MPa and the Young’s modulus increased from 282.51 ± 20.56 MPa to 988.69 ± 42.64 MPa for the 12 wt% HPP doped sample. Dynamic mechanical analysis (DMA) revealed that at elevated temperatures, enhanced mechanical properties because of the presence of HPP was even more noticeable. Morphological observations displayed no signs of agglomeration of HPP fillers even in composites with high HPP loading.

scholarly journals Hemp Fibre Reinforced Poly(Lactic Acid) Composites

2007 ◽  
Vol 29-30 ◽  
pp. 337-340 ◽  
Author(s):  
M.A. Sawpan ◽  
K.L. Pickering ◽  
Alan Fernyhough
Keyword(s):  
Lactic Acid ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Hemp Fibre ◽  
Reinforcing Material ◽  
Fibre Loading ◽  
The Degree Of Crystallinity

The potential of hemp fibre as a reinforcing material for Poly(lactic acid) (PLA) was investigated. Good interaction between hemp fibre and PLA resulted in increases of 100% for Young’s modulus and 30% for tensile strength of composites containing 30 wt% fibre. Different predictive ‘rule of mixtures’ models (e.g. Parallel, Series and Hirsch) were assessed regarding the dependence of tensile properties on fibre loading. Limited agreement with models was observed. Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) studies showed that hemp fibre increased the degree of crystallinity in PLA composites.

Properties of poly(lactic acid-co-glycolic acid) film modified by blending with polyurethane

2014 ◽  
Vol 68 (2) ◽  
Author(s):  
Guo-Quan Zhu ◽  
Fa-Gang Wang ◽  
Hong-Sheng Tan ◽  
Qiao-Chun Gao ◽  
Yu-Ying Liu
Keyword(s):  
Lactic Acid ◽  
Glycolic Acid ◽  
Chemical Properties ◽  
Tensile Tests ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Blend Films ◽  
Surface Contact Angle ◽  
Surface Morphologies ◽  
And Chemical Properties

AbstractA number of poly(lactic acid-co-glycolic acid)/polyurethane (PLGA/PU) blend films with various PU mole contents were prepared by casting the polymer blend solution in chloroform. The surface morphologies of the PLGA/PU blend films were studied by scanning electron microscopy (SEM). The thermal, mechanical and chemical properties of the PLGA/PU blend films were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile tests and surface contact angle tests. The results revealed that the introduction of PU could markedly modify the properties of PLGA films.

COST-FP1105: Properties of PLA films reinforced with unmodified and acetylated freeze dried nanofibrillated cellulose

Holzforschung ◽  
2016 ◽  
Vol 70 (12) ◽  
pp. 1125-1134 ◽  
Author(s):  
Vesna Žepič ◽  
Ida Poljanšek ◽  
Primož Oven ◽  
Matjaž Čop
Keyword(s):  
Heterogeneous System ◽  
Cellulose Nanofibrils ◽  
Composite Films ◽  
Hydrophobic Surface ◽  
Nanofibrillated Cellulose ◽  
Nanocomposite Films ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Elongation At Break ◽  
Freeze Dried

Abstract Freeze dried nanofibrils were acetylated in a heterogeneous system with acetic anhydride, pyridine, and dimethylformamide and the obtained acetylated cellulose nanofibrils (CNFac) were combined with poly(lactic acid) (PLA) to a composite. CNFac with its partially hydrophobic surface showed a good compatibility with PLA resulting in composite films with improved properties. Tensile strength (TS), modulus of elasticity (MOE), and elongation at break (EB) of PLA/CNF increased significantly when 2–5% of CNFac was added to the PLA matrix, while the addition of 10% and higher amounts CNFac decreased the EB at a higher TS and MOE. Mechanical parameters did not improve in the case of unmodified CNF addition. The addition of CNFac maintained transparency and had absorbance values between those of pure PLA film and PLA film with 2% CNF, while films formed with the addition of 5 and 10% of CNF were less transparent. The addition of CNF did not essentially affect the thermal properties of nanocomposite films. The addition of 2–10% of CNFac increased the enthalpy and maximal temperature of cold crystallization as opposed to higher loading of CNFac. The results of differential scanning calorimetry (DSC) coincide with those of the mechanical properties. Tailoring properties of PLA/CNF are only reproducible in case of homogenously distributed CNF within the PLA matrix and by an improved interphase adhesion between PLA and CNFac.

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.

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