Poly Lactic Acid Blends Research Articles

Partial Biodegradable Blend for Fused Filament Fabrication: In-Process Thermal and Post-Printing Moisture Resistance.

Despite the extensive research, the moisture-based degradation of the 3D-printed polypropylene and polylactic acid blend is not yet reported. This research is a part of study reported on partial biodegradable blends proposed for large-scale additive manufacturing applications. However, the previous work does not provide information about the stability of the proposed blend system against moisture-based degradation. Therefore, this research presents a combination of excessive physical interlocking and minimum chemical grafting in a partial biodegradable blend to achieve stability against in-process thermal and moisture-based degradation. In this regard, a blend of polylactic acid and polypropylene compatibilized with polyethylene graft maleic anhydride is presented for fused filament fabrication. The research implements, for the first time, an ANOVA for combined thermal and moisture-based degradation. The results are explained using thermochemical and microscopic techniques. Scanning electron microscopy is used for analyzing the printed blend. Fourier transform infrared spectroscopy has allowed studying the intermolecular interactions due to the partial blending and degradation mechanism. Differential scanning calorimetry analyzes the blending (physical interlocking or chemical grafting) and thermochemical effects of the degradation mechanism. The thermogravimetric analysis further validates the physical interlocking and chemical grafting. The novel concept of partial blending with excessive interlocking reports high mechanical stability against moisture-based degradation.

Influence of morphology on the dynamic and quasi‐static energy absorption of polylactic acid‐based lattice structures

AbstractThe aim of this work was to investigate the difference between energy absorption (EA) of a lattice structure under quasi‐static and dynamic loading, as influenced by morphology. Lattices were manufactured from blends of polylactic acid (PLA) and polycaprolactone (PCL), with and without a compatibilizer. Under quasi‐static compression, PLA and blends with low PCL content provided the greatest EA. Above 30% PCL, a drastic decrease in EA was observed as the ductility increased. The morphology of the blends under slower loading played little role in affecting EA, as the lattice's performance was mainly dictated by the ductility of the blend. However, under dynamic loading brittle lattices provided poor EA, however, at 30% PCL, EA was significantly higher, improved further with including a compatibilizer. At 10% PCL an erratic dispersion of PCL in the PLA matrix was observed, whilst at 50% the morphology was co‐continuous. A uniformly, finely dispersed droplet morphology was observed at 30% PCL. The ductility and morphology of the matrix paired with the complex loading scenario led to optimal EA under dynamic loading. The partial bonding between PCL and PLA provided clear improvement to EA, however, this effect was vastly different under quasi‐static loading.

Study some specifications of copolymer (PLA-PEG)

This study about the blends of Poly Lactic Acid/ Poly Ethylene Glycol (PLA/PEG) 4000 copolymer at concentrations (9%,6%,3%,0%)) wt%) from (PEG) and (PLA) (5%) (w/w) by using casting solvent method to production films. The nonwoven nano fibrous mats were obtained by electro spinning of (PLA/PEG) solutions in chloroform, at weight ratios (70/30) (v/v), respectively. DSC is employed to measure the crystallinity difference between (PLA/PEG) blends and their nonwovens mats. the thermal properties (DSC) of (PLA/PEG) copolymer blends films and electrospun nano fiber mats such as (Tm) melting temperature, (Tg) glass transition temperature, (Tc) crystallization, Xc crystallinity rate and enthalpy . the FTIR test was done for all samples to figure the nature linking between (PLA) and (PEG),the results were that (6%) (w/w) of (PEG) was the optimized rate to apply Electrospinning method , data of DSC test defined that (Tg) and (Tm) were decreased, and that refer to occurrence physicist cross linking between the used substances (Completely miscible blend) when the electrospinning method was applied, also Xc for these nonwoven mats was decreased which has in turn an important effect on the speed of biodegradble for poly lactic acid (PLA).

Influence of contact geometry over the filament bond of polylactic acid blends

Fused Filament Fabrication is one of the most common Additive Manufacturing technologies among industrial and domestic users because of the satisfying quality of parts and the great variety of thermoplastic polymers available on the market. New possibilities were provided along with the equipment with multiple extrusion systems, referring to multi-colour and multi-material components. Besides part orientation during the manufacturing process, filament bond influences the mechanical properties of parts produced through Fused Filament Fabrication technology. This paper aims to investigate if the bond performance for polylactic acid-based polymers can be enhanced by designing new contact geometries, different from the current surface-to-surface approach. To comprehensively understand the influence of the designed bonding geometries over the tensile strength, all specimens were produced according to a factorial design of experiment method and contact geometries constrained with function related to the nozzle size.

An investigation on the possible use of coffee silverskin in PLA/PBS composites

AbstractThe production of degradable packaging materials is a task that can be no longer postponed. Moreover, high amounts of agricultural wastes are landfilled without any recycling. In this research, the possibility to formulate particulate composites made of biopolymers filled with coffee waste with acceptable physical and mechanical characteristics that will degrade is investigated. The addition of this agricultural waste, by reducing the requested amount of biopolymer, can decrease the overall price of the material presently the main limiting factor to the use of biopolymers in the packaging industry. Silverskin, the integument of coffee beans discarded during the roasting process, after a milling step, is added up to a 30 wt% either to polylactic acid (PLA) or to a blend of PLA and polybutylene succinate. The filler can be homogeneously dispersed in both systems. The data shows that the silverskin filler increases the elastic modulus but decreases the tensile strength of the material and helps the development of crystal phase in the matrix. The thermal stability and the hydrophobicity of the materials stay almost unchanged on filler addition. Moreover, data shows that the addition of silverskin increases the materials susceptibility to microbial attack.

Natural Fiber-Reinforced Polylactic Acid, Polylactic Acid Blends and Their Composites for Advanced Applications.

Polylactic acid (PLA) is a thermoplastic polymer produced from lactic acid that has been chiefly utilized in biodegradable material and as a composite matrix material. PLA is a prominent biomaterial that is widely used to replace traditional petrochemical-based polymers in various applications owing environmental concerns. Green composites have gained greater attention as ecological consciousness has grown since they have the potential to be more appealing than conventional petroleum-based composites, which are toxic and nonbiodegradable. PLA-based composites with natural fiber have been extensively utilized in a variety of applications, from packaging to medicine, due to their biodegradable, recyclable, high mechanical strength, low toxicity, good barrier properties, friendly processing, and excellent characteristics. A summary of natural fibers, green composites, and PLA, along with their respective properties, classification, functionality, and different processing methods, are discussed to discover the natural fiber-reinforced PLA composite material development for a wide range of applications. This work also emphasizes the research and properties of PLA-based green composites, PLA blend composites, and PLA hybrid composites over the past few years. PLA’s potential as a strong material in engineering applications areas is addressed. This review also covers issues, challenges, opportunities, and perspectives in developing and characterizing PLA-based green composites.

Preparation, thermal degradation, and rheology studies for polylactic acid (PLA) and palm stearin (PS) blend: A review

In various types of applications, poly(lactic acid) (PLA) might be considered one of the potential alternatives to petrochemical-derived polymers such as polypropylene. However, PLA's disadvantages, such as its brittleness, heat characteristics, and degrading stability, restrict its use. To improve the aforementioned PLA qualities, polymerization, plasticization, and PLA blends are all being investigated. This research examines the production of PLA using various bio-based plasticizers to enhance the qualities of PLA, such as satisfying industrial requirements and recognising the limitations of each modification. Due to favourable results from other palm oil-based plasticizers described in various polymer modification works, palm stearin is a new candidate considered to be a strong option as a plasticizer to overcome the limits of PLA. Palm stearin is a co-product of palm olein and, it is always traded at a discount to palm oil and palm olein. Considering PLA and palm stearin are potentially prepared by melt-blending, the thermal properties such as glass transition temperature (Tg), cold crystallization temperature (Tcc), and the melting temperature (Tm) are critical to be investigated further for this blend because of the partial crystallization properties of palm stearin, which are characterized by differential scanning calorimetry (DSC) under a nitrogen atmosphere. Characterizations such as torque, rheology, and Fourier Transform Infrared Spectroscopy (FTIR) were also reviewed on the plasticized PLA to study the compatibility and the biodegradable of this plasticized PLA. From this review, a suitable processing design for PLA and palm stearin blend was determined, and the thermal and rheology characteristics for PLA and the bio-plasticizer were successfully reviewed.

Preparation of an oxyalkylated lignin‐g‐polylactic acid copolymer to improve the compatibility of an organosolv lignin in blended poly(lactic acid) films

AbstractTo improve the compatibility of an organosolv lignin (OL) in polylactic acid (PLA) blends, a green approach was pursued whereby the lignin was modified with propylene carbonate (PC) to increase its aliphatic hydroxyl content, and thereby, its reactivity. The oxyalkylated organosolv lignin (OOL, synthesized at 170°C) was analyzed by quantitative 31P NMR and showed the number of phenolic hydroxyls decreased from 4.73 to 0.16 mmol·g−1, and the number of aliphatic hydroxyls increased from 3.56 to 3.92 mmol·g−1. OOL‐g‐PLA copolymer (OOLPC) samples were prepared by graft polymerization of L‐lactide with the OOL and showed the molecular weights (Mn) to range from 12,343 to 16,834 Da, increasing with the lignin loading of the copolymer. Scanning electron microscope indicated that the graft copolymerization reaction between L‐lactide and the OOL afforded a copolymer that was compatible with PLA. The highest increase in elongation at break was 7.43% for the PLA blend films prepared with the OOLPC having a 5.0% loading of OOL; the tensile strength at this level of lignin loading was 12.03% lower. Introducing an OL into the blend films showed excellent ultraviolet absorption ability and thus the OOLPC could be used as a well‐dispersed UV‐blocking agent for biocompatible packaging materials.

Polylactic Acid and Poly(Butylene Adipate-Co-Terephthalate) Blends Plasticised with Lactic Oligomers and Epoxy Reactive Plasticizers

Polylactic acid (PLA) is a compostable and sustainable polymer, derived from renewable resources, with high elastic modulus and high transparency. By the way PLA has even some limitations such as low glass transition temperature, low thermal stability, high brittleness, and low crystallization rate. To increase flexibility of PLA based materials it is possible to add low molecular weight plasticizers or prepare blends with another flexible polymer, such as poly(butylene adipate-co-terephthalate) (PBAT). Even the use of a compatibilizer may allow a modulation of mechanical properties thanks to the achievement of a phase morphology characterized by a lower dimension of the dispersed PBAT phase and an increased adhesion. In the present study, blends of PLA and PBAT were prepared by adding different plasticizers combinations based on an oligomer of lactic acid, a polyester of adipic acid and 1,2-propane diol, and an epoxy functionalised resin. All the plasticizers were effective in providing flexibility to the blends, with higher efficiency from the epoxy functionalised plasticizer, and the polyester of adipic acid. Fox’s equation showed that all plasticizers have the tendency to disperse more in the amorphous PBAT matrix than in the PLA one.

Partial Polymer Blend for Fused Filament Fabrication with High Thermal Stability.

The materials for large scale fused filament fabrication (FFF) are not yet designed to resist thermal degradation. This research presents a novel polymer blend of polylactic acid with polypropylene for FFF, purposefully designed with minimum feasible chemical grafting and overwhelming physical interlocking to sustain thermal degradation. Multi-level general full factorial ANOVA is performed for the analysis of thermal effects. The statistical results are further investigated and validated using different thermo-chemical and visual techniques. For example, Fourier transform infrared spectroscopy (FTIR) analyzes the effects of blending and degradation on intermolecular interactions. Differential scanning calorimetry (DSC) investigates the nature of blending (grafting or interlocking) and effects of degradation on thermal properties. Thermogravimetric analysis (TGA) validates the extent of chemical grafting and physical interlocking detected in FTIR and DSC. Scanning electron microscopy (SEM) is used to analyze the morphology and phase separation. The novel approach of overwhelmed physical interlocking and minimum chemical grafting for manufacturing 3D printing blends results in high structural stability (mechanical and intermolecular) against thermal degradation as compared to neat PLA.

Mechanical Properties and In Vitro Evaluation of Thermoplastic Polyurethane and Polylactic Acid Blend for Fabrication of 3D Filaments for Tracheal Tissue Engineering

Surgical reconstruction of extensive tracheal lesions is challenging. It requires a mechanically stable, biocompatible, and nontoxic material that gradually degrades. One of the possible solutions for overcoming the limitations of tracheal transplantation is a three-dimensional (3D) printed tracheal scaffold made of polymers. Polymer blending is one of the methods used to produce material for a trachea scaffold with tailored characteristics. The purpose of this study is to evaluate the mechanical and in vitro properties of a thermoplastic polyurethane (TPU) and polylactic acid (PLA) blend as a potential material for 3D printed tracheal scaffolds. Both materials were melt-blended using a single screw extruder. The morphologies (as well as the mechanical and thermal characteristics) were determined via scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, tensile test, and Differential Scanning calorimetry (DSC). The samples were also evaluated for their water absorption, in vitro biodegradability, and biocompatibility. It is demonstrated that, despite being not miscible, TPU and PLA are biocompatible, and their promising properties are suitable for future applications in tracheal tissue engineering.

The effect of electrospun polylactic acid/chitosan nanofibers on the low density polyethylene/ploy lactic acid film as bilayer antibacterial active packaging films

Bilayer antibacterial films were prepared using electrospun polylactic acid (PLA)/chitosan (Ch) nanofiber on low-density polyethylene (LDPE)/PLA films. Blends of Ch and PLA with the selected ratios of 5.0%, 10.0%, 15.0%, and 20.0% Ch were electrospun on the surface of LDPE/PLA composite film. Scanning electron microscopic images indicated a smooth and bead-free surface for all composite nanofibers with a diameter range from 50–200 nm. Fourier transform infrared spectra depict the presence of PLA and CH in the nanofiber. Hydrophobicity analysis showed that the PLA/Ch layer increase the hydrophobicity of bilayer films. The water vapor permeabilities of bilayer films were lower than those of LDPE/PLA film. The presence of PLA/Ch nanofiber layer resulted in the reduction in the oxygen permeability of bilayer films. When Ch content reached 10.0%, the bilayer films showed antibacterial activities against Escherichia coli and Staphylococcus aureus. Novelty impact statement Blends of chitosan and polylactic acid (PLA) was electrospun on to the surface of a low-density polyethylene (LDPE)/PLA film to produce bilayer antibacterial films. Electrospun nanofiber layers improved the antibacterial properties of the films and also reduced the oxygen and water vapor permeability levels of LDPE/PLA composite films without major interferences with their intrinsic physical and barrier properties.

Nanocrystallisation and self-assembly of biosourced ferulic acid derivative in polylactic acid elastomeric blends

Hypothesis.The crystallisation of biosourced ferulic acid derivatives - Bis-O-feruloyl-1,4-butanediol (BDF) - in a polylactic acid (PLA) matrix produces thermoplastic elastomeric blends that are transparent and biodegradable. Elastomeric and transparency are controlled by the domain size. PLA-BDF blends up to a threshold BDF concentration providing elastomeric properties show no evidence of BDF crystallisation. Heat treatment weakens the PLA-BDF interaction, give BDF molecules mobility to interact with nearby BDF molecules, leading to BDF nano-crystallisation.Experiments.PLA-BDF blends were synthesised by hot-melt processing by mixing pure PLA with different concentrations of BDF (0–40 wt%) at 180 °C for 13 min. One set of blends was annealed at 50 °C for 24 h and compared with the unannealed set. The BDF crystallisation in the blends is studied by combining SAXS, SEM, XRD and Polarised Optical Microscopy. Monte-Carlo simulations were performed to validate SAXS data analysis.Findings.Unannealed PLA-BDF blends of up to the threshold of 20 wt% BDF are dominated by the semicrystalline behaviour of PLA, without any trace of BDF crystallisation. Surprisingly, the PLA-BDF 40 wt% blend shows BDF crystallisation in the form of large and nanoscale structures bonded together by weak interparticle interaction. At concentrations up to 20 wt%, the BDF molecules are homogenously dispersed and bonded with PLA. Increasing BDF to 40 wt% brings the BDF molecules close enough to crystallise at room temperature, as the BDF molecules are still bonded with the PLA network.Annealing of PLA-BDF blends led to BDF nanocrystallisation and self-assembling in the PLA network. Both BDF nanoparticle size and interparticle distance decrease as the BDF concentration increases. However, the number density of BDF nanocrystals increases. The formed BDF nanocrystals have size ranging between 100 and 380 Å with interparticle distance of 120–180 Å. The structure factor and potential mean force confirm the strong interparticle interaction at the higher BDF concentration. Heat treatment weakens the PLA -BDF interaction, which provides mobility to the BDF molecules to change conformation and interact with the nearby BDF molecules, leading to BDF crystallisation. This novel BDF crystallisation and self-assembly mechanism can be used to develop biodegradable shape memory PLA blends for biomedical, shape memory, packaging and energy applications.

Effects of Processing Conditions and Plasticizing-Reinforcing Modification on the Crystallization and Physical Properties of PLA Films.

The polylactic acid (PLA) resin Ingeo 4032D was selected as the research object. Epoxy soybean oil (ESO) and zeolite (3A molecular sieve) were used as plasticizer and reinforcing filler, respectively, for PLA blend modification. The mixture was granulated in an extruder and then blown to obtain films under different conditions to determine the optimum processing temperatures and screw rotation. Then, the thermal behaviour, crystallinity, optical transparency, micro phase structure and physical properties of the film were investigated. The results showed that with increasing zeolite content, the crystallization behaviour of PLA changed, and the haze of the film increased from 5% to 40% compared to the pure PLA film. Zeolite and ESO dispersed in the PLA matrix played a role in toughening and strengthening. The PLA/8 wt% zeolite/3 wt% ESO film had the highest longitudinal tensile strength at 77 MPa. The PLA/2 wt% zeolite/3 wt% ESO film had the highest longitudinal elongation at 13%. The physical properties depended heavily on the dispersion of zeolite and ESO in the matrix.

Mechanical and Rheology Properties of PLA/ABS/TCS Polymer Blends

Binary and ternary blends of poly lactic acid (PLA), acrylonitrile-butadiene-styrene (ABS) and tapioca cassava starch (TCS) were prepared by the help of melt blend method. Rheological and mechanical properties of the prepared blends were studied. Rheological properties were studied using capillary Rheometer, shear rate, shear stress, the non-Newtonian index, were determined .Mechanical properties were studied in terms of tensile properties, stress at break, strain at break and Young's modulus have been determined by help of Universal Test Machine (UTM-3969).The results shows the ternary blends reveals shear-thinning behavior, over the range of the studied shear rates where the true shear rate of the blend decreases while increasing the shear rate. It also found that the true viscosity of the blend decreases with increased ABS content.

Poly (vinyl alcohol)/polylactic acid blend film with enhanced processability, compatibility, and mechanical property fabricated via melt processing

AbstractPoly (vinyl alcohol)/polylactic acid (PVA/PLA) blend film, which is environment friendly and has potential applications in food and electronic packaging fields, was fabricated by melt extrusion casting. Fourier transform infrared spectroscopy analysis confirmed the formation of the hydrogen bonding between PLA and PVA, which improved the compatibility of PLA with PVA, making PLA uniformly dispersed in PVA matrix as small spheres, even when PLA content increase to 15 wt%. In this way, the original hydrogen bond network among PVA was disturbed and the chain mobility of PVA was activated, endowing PVA/PLA blends with lower melt viscosity than bot modified PVA and PLA, and the blend films with the increased crystallinity, mechanical property, and water resistance. Compared with PVA film, the crystallinity, tensile strength and Young's modulus of the blend film with 15 wt% PLA, respectively, increased by 15.1%, 9 and 51 MPa, and the water contact angle enlarged from 23° to 60°.

Architected poly(lactic acid)/poly(\u03b5-caprolactone)/halloysite nanotube composite scaffolds enabled by 3D printing for biomedical applications

Herein, we report the physicochemical, thermal, mechanical and biological characteristics, including bioactivity, biodegradation and cytocompatibility of additive manufacturing-enabled novel nanocomposite scaffolds. The scaffolds comprise a blend of polylactic acid (PLA) and poly-ε-caprolactone (PCL) reinforced with halloysite nanotubes (HNTs). The nanoengineered filaments were developed by melt blending, and the nanocomposite scaffolds were manufactured by fused filament fabrication. Uniform dispersion of HNTs in the PLA/PCL blend is revealed via scanning electron microscopy. Mechanical property loss due to the addition of PCL to realize a suitable biodegradation rate of PLA was fully recovered by the addition of HNTs. Bioactivity, as revealed by the fraction of apatite growth quantified from XRD analysis, was 5.4, 6.3, 6.8 and 7.1% for PLA, 3, 5 and 7 wt% HNT in PLA/PCL blend, respectively, evidencing enhancement in the bioactivity. The degradation rate, in terms of weight loss, was reduced from 4.6% (PLA) to 1.3% (PLA/PCL) upon addition of PCL, which gradually increased to 4.4% by the addition of HNTs (at 7 wt% HNT). The results suggest that the biodegradation rate, mechanical properties and biological characteristics, including cytocompatibility and cell adhesion, of the 3D printed, microarchitected PLA/PCL/HNT composite scaffolds can be tuned by an appropriate combination of HNT and PCL content in the PLA matrix, demonstrating their promise for bone replacement and regeneration applications.Graphical abstract

Biodegradable Active Packaging as an Alternative to Conventional Packaging: A Case Study with Chicken Fillets

Innovative active packaging has the potential to maintain the food quality and preserve the food safety for extended period. The aim of this study was to discover the effect of active films based on commercially available polylactic acid blend (PLAb) and natural active components on the shelf life and organoleptic properties of chicken fillets and to find out; to what extent they can be used as replacement to the traditional packaging materials. In this study, commercially available PLAb was compounded with citral and cinnamon oil. Active films with 300 µm thickness were then produced on a blown film extruder. The PLAb-based films were thermoformed into trays. Fresh chicken breast fillets were packed under two different gas compositions, modified atmosphere packaging of 60% CO2/40% N2, and 75% O2/25% CO2 and stored at 4 °C. The effect of active packaging materials and gas compositions on the drip loss, dry matter content, organoleptic properties, and microbial quality of the chicken fillets were studied over a storage time of 24 days. The presence of active components in the compounded films was confirmed with FTIR, in addition the release of active components in the headspace of the packaging was established with GC/MS. Additionally, gas barrier properties of the packages were studied. No negative impact on the drip loss and dry matter content was observed. The results show that PLAb-based active packaging can maintain the quality of the chicken fillets and have the potential to replace the traditional packaging materials, such as APET/PE trays.

Vibrational Spectroscopy Analysis of Oligothiophene Blend Film

One of the challenges in fabricating organic semiconductor thin film is to produce bettermolecular ordering that compromise its electronic properties. Molecular ordering of amorphous thin film can be improved in many ways. Here, high molecular weight polylactic acid (PLA) is introduced as binding matrix to promote 3'''-didodecyl-2,2':5',2'':5'',2'''-quaterthiophene (4T) film’s homogeinity across indium tin oxide (ITO) surface. Molecular ordering of the spin coated biodegradable PLA and 4T blend film processed at ambient atmosphere was studied using two vibrational spectroscopy methods. The complementary analysis of infrared absorption spectrum and Raman spectrum had identified several vibrational modes contributed by thiophene rings and alkyl functional groups. The Raman analysis implied there is a slight change of thiophene ringsʼ molecular orientation due to compressive stress after introduction of polymer. Microscopic characteristics of oligothiophenes especially at the π-π conjugated backbones contained crucial information in order to exploit the oligothiophene as flexible electronics devices.

Electrospun PLGA/SF/artemisinin composite nanofibrous membranes for wound dressing

Combining biodegradable materials with natural plant components for wound dressing has been receiving significant attention. ART is a sesquiterpene lactone compound extracted from Artemisia annua L., possessing multiple pharmacological effects including antibacterial activity and anti-inflammatory property. Herein, the blended polylactic acid glycolic acid (PLGA)/silk fibroin (SF) membranes loaded with artemisinin (ART) are fabricated through electrospinning. With aid of SF, the fabricated membranes have a good sustained-release effect, and the accumulated ART release can reach 69% after three weeks. PLGA/SF/ART membranes exhibit favorable anti-inflammatory and cell compatibility in vitro evaluations. The in vivo experiment indicates that PLGA/SF/ART2 membranes can shorten the inflammation period and enhance skin regeneration in a full-thickness wound model through down-regulating the expressions of pro-inflammatory cytokines IL-1β and TNF-α. To sum up, the fabricated PLGA/SF/ART2 composite membranes with anti-inflammatory properties can be a proposal wound dressing for chronic wound healing.