Thermoplastic Films Research Articles

Rice thermoplastic starch nanocomposite films reinforced with nanocellulose

Abstract Rice starch is a raw material with proven potential in obtaining biodegradable polymers. Plasticization improves the flexibility characteristics of starch-based films, although they still tend to have low tensile strength and high hydrophilicity. The addition of nanocellulosic materials is an alternative to improve these characteristics. In this chapter, the effects of adding different sources and concentrations of nanocellulose (NC) on the properties of thermoplastic rice starch films (TRSF) are addressed. One can highlight as main effects the increase of tensile strength and transparency of the films, the reduction of water vapor permeability and water solubility. The type of NC used, the way it is obtained, as well as its interaction with starch molecules are factors that influence the effects. Further studies involving the interaction of TRSF and NC should be conducted in order to overcome the lack of information.

Barley thermoplastic starch nanocomposite films reinforced with nanocellulose

Abstract Despite being one of the starch producers, barley has yet to be widely studied for thermoplastic starch applications, including nanocellulose thermoplastic composites, due to its uses in the food and beverage industries. However, only 20% of barley is used in the malting industry to produce both alcoholic and non-alcoholic beverages, and 5% is used as an ingredient in a wide variety of foods. As the fourth most important cereal in the world after wheat, corn, and rice, barley can be considered an interesting biomass source to produce biodegradable thermoplastics, stemming from its starch constitution. Therefore, this review attempts to highlight the barley starch properties and its potential utilization for nanocellulose thermoplastic starch composites. Several studies involving barley-based starch in thermoplastic production and nanocellulose reinforcement for properties enhancement are also reviewed, particularly in the attempt to provide various options to reduce and replace the uses of harmful petroleum-based plastic.

Wheat thermoplastic starch composite films reinforced with nanocellulose

Abstract The rising costs of non-renewable plastic and environmental concerns with their industrial usage have encouraged the study and development of renewable products. As an alternative, biological-based materials create a huge opportunity for a healthy and safe environment by replacing non-renewable plastic in a variety of applications. Wheat is one of the world’s most widely cultivated crops. Due to its mechanical and physical properties, wheat starch is vital in the biopolymer industry. Wheat thermoplastic starch exhibits useable properties when plasticizers, elevated temperatures and shear are present. Thus, make it very suitable to be used as packaging material. However, this material suffers from low mechanical properties, which limit its applications. Several studies looked at the feasibility of using plant components which is nanocellulose as a reinforcing agent in wheat starch thermoplastic composites. Overall, the addition of nanocellulose can improve the performance of wheat thermoplastic starch, especially for its mechanical properties. It can potentially be used in several areas of packaging and biomedical. The objective of this review is to discuss several achievements regarding wheat starch/nanocellulose-based composites. Several important aspects of the mechanical performance and the thermal properties of the composites were evaluated. The discussion on wheat starch and nanocellulose was also tackled in this review.

Potato thermoplastic starch nanocomposite films reinforced with nanocellulose

Abstract Potato is a widely available feedstock with biocompatibility and biodegradability properties, making it a strong candidate for producing thermoplastic starch. The application of thermoplastic starch to replace petroleum-based plastic as a sustainable and environmentally friendly approach led to its further improvement through various techniques such as modification and filler reinforcement. Numerous studies have been done addressing the properties enhancement of potato thermoplastic starch through filler reinforcement including nanocellulose. This review focus on the recent and future potential of potato-based starch as one of the feedstocks for producing potato thermoplastic starch composites reinforced with nanocellulose.

Effects of primary, secondary and tertiary structures on functional properties of thermoplastic starch biopolymer blend films

To better understand the correlation between structure and properties in thermoplastic starch biopolymer blend films, the effects of amylose content, chain length distribution of amylopectin and molecular orientation of thermoplastic sweet potato starch (TSPS) and thermoplastic pea starch (TPES) on microstructure and functional properties of thermoplastic starch biopolymer blend films were studied. After thermoplastic extrusion, the amylose contents of TSPS and TPES decreased by 16.10 % and 13.13 %, respectively. The proportion of the chains with the degree of polymerization between 9 and 24 of amylopectin in TSPS and TPES increased from 67.61 % to 69.50 %, and from 69.51 % to 71.06 %, respectively. As a result, the degree of crystallinity and molecular orientation of TSPS and TPES films increased as compared to sweet potato starch and pea starch films. The thermoplastic starch biopolymer blend films possessed a more homogeneous and compacter network. The tensile strength and water resistance of thermoplastic starch biopolymer blend films increased significantly, whereas thickness and elongation at break of thermoplastic starch biopolymer blend films decreased significantly.

On the application of strong thermoplastic–thermoset interactions for developing advanced aerospace-composite joints

In this study, an aerospace thermosetting composite was co-curing joined by Polyether-ether-ketone (PEEK) and Polyethylenimine (PEI) films, with an aim of developing advanced composite joints. The semi-crystalline PEEK films were surface activated upon a UV-irradiation technique to obtain a strong film–composite interface, while the amorphous PEI films could be directly used. The fracture behaviour of the composite joints was evaluated and compared with benchmark aerospace adhesive joints. The experimental results proved remarkable mode-I and mode-II fracture resistance of the PEEK co-cured joints at 22 °C and 130 °C, while the PEI co-cured joints exhibited excellent mode-I fracture resistance at 22 °C and mode-II fracture resistance in both testing temperature cases. Extensive elongation, tearing and fracture of the PEEK/PEI plastics were proved to be the main mechanisms for toughness enhancement. Overall, this work had successfully demonstrated the effectiveness of developing advanced composite joints via a co-curing process using high-performance thermoplastic films.

Enhanced tensile and barrier properties of modified LLDPE with rubbery materials and graphene nanoplatelets for packaging application

AbstractLinear low‐density polyethylene (LLDPE) is widely used in industries. It possesses remarkable characteristics such as low density, easy to process, and recyclable. However, LLDPE‐based products are known to be highly permeable to water and oxygen, thus limiting their application as packaging material. In this study, natural rubber (NR) and graphene nanoplatelets (GNP) were mixed with LLDPE to produce thermoplastic elastomer nanocomposites films as a novel, potential packaging material with the aid of liquid natural rubber (LNR) as compatibilizing agent. The formulation modification of GNP, NR, and LNR components influenced the mechanical and barrier properties of the resulting nanocomposites. The mixing methods, i.e., direct melt‐mixing and masterbatch mixing (MB) were also investigated. Apparently, tensile test for samples prepared from MB mixing method yielded better results compared to samples from direct melt‐mixing. Permeability tests of water vapor (WVP) and oxygen (OTR) demonstrated that LLDPE/GNP/NR/LNR nanocomposites films managed to reduce the permeability rate of WVP and OTR of pure LLDPE by 92.73% and 98.60%, respectively. The tortuous theory had been confirmed that the experimental data best fit the Nielsen model at aspect ratio of 20, 30 and 10, 20, 40, 200 for WVP and OTR, respectively.

Tensile behavior of individual fibers and films made via material extrusion additive manufacturing

The mechanical behavior of thermoplastic materials processed via material extrusion additive manufacturing (MEAM) is a topic of great interest in several disciplines. Most of the material behavior characterization that has been done on the materials produced by material extrusion has been on macro-scale (“bulk”) parts. In order to better model and understand the process effects and take advantage of these during design, it is necessary to study the meso-scale material elements extruded by the process used to build the part geometry. While modeled effectively in previous works, full mechanical characterization at the meso-scale is yet to be accomplished. At this level, the essential material elements are known as “beads” or “roads”, the sum of which comprise each layer of the part. These elements are approximately uniform in cross-section and are defined by their dimensions, length, and placement angle. Therefore, they are effectively fibers and a set of them together constitute a layer, which can be built as a film (usually but not always flat). To further progress on this topic, this article explored the manufacturing and testing of these elements (fibers) and layers (films) at the meso-scale. The dimensional consistency was measured for each case in order to determine the process repeatability, followed by tensile tests on the fibers and films made from three common thermoplastic materials: Acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and polycarbonate (PC). For the fibers, both extruded (round, as produced) and deposited (rectangular, after printing on a surface) fibers were tested. Films were tested in single- and double-layer configurations with several different element layout patterns. The results and potential process sensitivities were discussed in detail, providing recommendations for use and future development of design rules when using these materials. These results will be useful in driving design decisions (for both macro-scale products and structured materials) and providing characterization data for further modeling and simulation of the MEAM process. These results will also help ensure the manufacturability of designed parts and materials built of these deposited thermoplastic fibers and films. This article also introduced and described mechanical testing methods that are useful for thermoplastic MEAM parts and have not yet been utilized elsewhere.

Crop Nitrogen Fertilization Schedule in Bread Wheat Affects the Mechanical Performances of Thermoplastic Films Obtained by Plasticization of Flours

Recent research has investigated the plasticization of wheat flour as a non-food alternative application. In this work, we analyzed the performances of thermoplastic films obtained using flours of two bread wheat cultivars (Bologna and Bora) grown in fall–spring under four nitrogen (N) fertilization treatments: (1) continuously well-N-fed (N300 = 300 kg N ha−1, split throughout the growth cycle); (2) N-fed only very early (N60-0 = 60 kg N ha−1, just one month after sowing); (3) N-fed only extremely late (N0-120 = 120 kg N ha−1 at pollination); (4) unfertilized control (N0). Flours were characterized for glutenin and gliadin fractions, Chopin’s alveograph parameters, Field Emission Scanning Electron Microscopy (FESEM) images, and thermogravimetric analysis (TGA), while films were evaluated for mechanical properties (tensile strength at break, σb; elongation at break, εb; Young’s modulus, E) and FESEM images. Differences among treatments for absolute and relative abundances of gluten fractions and alveographic parameters were extremely marked and gave rise to differences in tensile properties of thermoplastic films. Within each cultivar, the ranking of treatments for εb values was N0 > N60-0 > N0-120 > N300. Thus, εb was inversely correlated with crop N availability and total gluten content of the flour. The σb was less variable among N treatments; however, in both cultivars, it was high in N0 and N300 and appreciably lower in N0-120. Overall, the best mechanical performances were obtained with flours from crops not subjected to imbalances in N nutrition (N0, N300). Our work demonstrates that bioplastic engineering needs to take into consideration the variability of biological source material like that caused by different crop N availability.

Evolution of the free volume during water desorption in thermoplastic starch/citric acid films: In situ positron annihilation studies

The effect of citric acid (CA) concentration and water content on the free hole volume of thermoplastic cassava starch films (TPS) was studied. To this aim, continuous in situ positron annihilation lifetime spectroscopy measurements were performed at fixed moisture content and during water desorption. The results show that the increase in CA concentration leads to wider free hole volume distributions with lower mean values. During water desorption, the mean values and width of such distributions systematically decrease with the exposure time, and the evolution of the hole volumes was well-described using the Kohlrausch-Williams-Watts function. The water vapour permeability was significantly higher in films incorporating 5 % (w/w) of CA, in line with the more open network of this material that was revealed in the hole volumes distribution. The Young's modulus of all the developed films increased significantly after partial water desorption, which was attributed to the plasticizer loss reflected in a decrease in the mean hole volume value (between 4 % and 13 %). This work evidences that the control and report of the relative humidity are essential when testing TPS-based films, as their nanostructures are strongly dependent on external conditions.

Supercritical CO2 permeation in polymeric films: Design, characterization, and modeling

This study is concerned with the development of an optimum method for identification of supercritical CO2 permeability in thermoplastic films with moderate to excellent barrier properties namely, High-Density Polyethylene (HDPE), Raised-Temperature Polyethylene (PE-RT), Polyvinylidene Fluoride (PVDF) and aliphatic Polyketone (PK) at elevated temperatures (40 °C−82 °C). A high-temperature/high-pressure permeation cell was designed based on the “closed-volume/variable pressure” standard test method. The identified gas transport properties using the time lag method yielded significant error particularly for PVDF and PK, which was ascribed to the sole reliance on the accumulated pressure-rate in steady-state. This error was minimized using the Non-Linear Regression (NLR) by utilizing the full range of measured data including the transient state. The coefficient of determination between the measured and modeled data using NLR was quantified above 0.99 for all the polymers at the entire examined temperature range. The 1.4 % higher degree of crystallinity and 28.5 % smaller spherulite size caused 13.3 % higher diffusivity and 8.6 % lower solubility in PE-RT when compared with HDPE at 82°C. As a result of this trade-off, PE-RT exhibited only 3.5 % higher permeability than HDPE. The developed generalized temperature-dependent model provided the essential data for design optimization of gas barrier performance in multilayer high-temperature pressure-vessels.

Effects of different sources of cellulose on mechanical and barrier properties of thermoplastic sweet potato starch films

Sweet potato starch and different celluloses were mixed by thermoplastic extrusion and then thermoplastic starch/cellulose composite films were prepared using a casting method. The effect of different celluloses on the mechanical and barrier properties of thermoplastic sweet potato starch films were studied and compared. The results indicated that among thermoplastic starch/cellulose composite films, the hydrogen bond interaction between starch and sugarcane cellulose was more obvious and the crystallization melting temperature difference was smaller, indicating better compatibility between sugarcane cellulose and sweet potato starch. Thermoplastic starch/sugarcane cellulose film had the largest FTIR ratio values of 1047 cm−1/1022 cm−1, resulting in the highest tensile strength (3.75 MPa), largest contact angle (68.44°), or stronger surface hydrophobicity. Thermoplastic starch/cornstalk cellulose film had the highest thermal degradation temperature (325 °C). Thermoplastic starch/wheat or bamboo cellulose film had lower UV transmittance (about 36%), indicating stronger UV Resistance. Thermoplastic starch/rice bran cellulose film had the largest elongation at break value (49.03%). Thermoplastic starch/bamboo or cornstalk cellulose films had lower water vapor permeability, whereas thermoplastic starch/rice bran cellulose had higher water vapor permeability. The outcoming would provide a new theoretical basis for choosing an optimal cellulose compatible with thermoplastic sweet potato starch to enhance mechanical properties, water resistance and barrier property of thermoplastic starch films.

Thermoplastic polyurethane film performance improvement by incorporation of furfuryl alcohol and polydimethylsiloxane

Thermoplastic polyurethanes (TPUs) films, widely used in industry and domestic, are required to have self/stimulate-healing ability and multifunction to achieve its recycling usage and adapt complex environment. Herein, the novel TPUs (PDMS/FA-PUDAs) were prepared by incorporation of biomass furfuryl alcohol (FA) and non-toxic polydimethylsiloxane (PDMS) through classic polymerization route accompanied by Diels-Alder (DA) reaction. This study investigated the combined effect of DA/rDA reaction and PDMS on improving TPU films' stimulate-healing, mechanical and anti-adhesion properties by adjusting PDMS additive amount. The experimental results demonstrated that 10 wt% PDMS and FA modified TPU film (10 % PDMS/FA-PUDA) still remained high stimulate-healing efficiency (73.48 %) after three times repair process, owing to the DA/rDA reaction was reversible between FA and bismaleimide (BMI). Besides, 10 % PDMS/FA-PUDA had superior pristine mechanical properties (Ts: 72.06 MPa, Eb: 162.45 %, Tt: 10.89 MJ/m3) because PDMS promoted the formation of microphase separation structure. Moreover, the film surface presented low surface free energy (16.79 mJ/m2) and satisfactory anti-adhesion behavior ascribed to the hydrophobicity of PDMS. This investigation might give a new perspective for designing multifunctional TPU using renewable and non-toxic materials.

Use of Rotary Ultrasonic Plastic Welding as a Continuous Interconnection Technology for Large-Area e-Textiles

For textile-based electronic systems with multiple contacts distributed over a large area, it is very complex to create reliable electrical and mechanical interconnections. In this work, we report for the first time on the use of rotating ultrasonic polymer welding for the continuous integration and interconnection of highly conductive ribbons with textile-integrated conductive tracks. For this purpose, the conductive ribbons are prelaminated on the bottom side with a thermoplastic film, which serves as an adhesion agent to the textile carrier, and another thermoplastic film is laminated on the top side, which serves as an electrical insulation layer. Experimental tests are used to investigate the optimum welding process parameters for each material combination. The interconnects are initially electrically measured and then tested by thermal cycling, moisture aging, buckling and washing tests, followed by electrical and optical analyses. The interconnects obtained are very low ohmic across the materials tested, with resulting contact resistances between 1 and 5 mOhm. Material-dependent results were observed in the reliability tests, with climatic and mechanical tests performing better than the wash tests for all materials. In addition, the development of a heated functional prototype demonstrates a first industrial application.

Controlling the properties of thermoplastic starch films with hydrogen bonding plasticizers

Four deep eutectic solvents were used to produce plasticized thermoplastic starch films by a solution casting method. The mechanical properties of thin films, the stability of these properties over time, and the effects of humidity were investigated with the quartz crystal microbalance. The crystallinity, glass transition temperature, modulus and elongation at break for thicker films was measured using a combination of x-ray diffraction, differential scanning calorimetry and tensile testing. The films had very low glass transition temperatures (-50 ∘C or lower), with mechanical properties determined by the crystallinity of the films. The crystallinity did not change significantly over a period of one week, giving materials with a stable mechanical response. Deep eutectic solvents containing ammonium acetate, glycerol, and urea produced films with a crystalline structure that was much more stable at high humidity values than films plasticized only with glycerol or a traditional ionic liquid. These effects are attributed to the complex hydrogen bonding interactions between the different components of the deep eutectic solvents, and between these components and the starch polymer.

Influence of Urea Content in Deep Eutectic Solvents on Thermoplastic Starch Films’ Properties

The goal of the study was to prepare deep eutectic solvents (DESs) with different urea (U) contents and apply them as potato-starch plasticizers to investigate the influence of various DES compositions on the physicochemical properties of thermoplastic starch (TPS) obtained via thermocompression. As hydrogen bond acceptors, quaternary ammonium compounds, choline chloride (CC) and betaine (B-anhydrous and monohydrate) were used. The molar ratios of CC or B to U were 1:2, 1:3, 1:4 and 1:5. Before starch processing, the DESs were thermally characterized (DSC, TGA). The increase in U content in the eutectics led to higher phase-transition temperatures and lower thermal stability. The influence of the DESs on thermocompressed TPS mechanical (tensile test) and thermal–mechanical (DMTA) properties, morphology (XRD and FTIR), sorption/dissolution behavior and surface contact angle was investigated. The mechanical tests revealed that the increase in U led to higher elongation at break and a highly amorphous structure. The FTIR results indicated that the starch underwent some carbamation derivatization with the presence of B. The DESs with high U content plasticized starch effectively; therefore, preliminary extrusion tests for starch were performed with selected CC and B-based DES with the molar ratio of 1:5.

Enhancing the Thermo-Mechanical Properties of Thermoplastic Starch Films Using Rice Straw Fibers as Reinforcement

Enhancing the Thermo-Mechanical Properties of Thermoplastic Starch Films Using Rice Straw Fibers as Reinforcement

On the Hot-Plate Welding of Reactively Compatibilized Acrylic-Based Composites/Polyamide (PA)-12.

Joining of dissimilar thermoplastics and their composites is a challenge for thermal welding techniques due to different melting points. Reactive welding with an auxiliary functional material can offer the clear opportunities to develop joining processes due to robustness to joining dissimilar thermoplastic polymers and their composites. The current study employed reactive compatibilization to offer the possibility of joining an acrylic-based glass fiber composite to polyamide (PA)-12 by applying a hot-tool welding technique. For this purpose, composite plates are fabricated by a typical vacuum infusion and thin layer thermoplastic films are formed by a thermostamping of PA12 granules. Subsequently, the reactive welding of the interposed PA12 sheet and Elium®-GMA-Glass composite is conducted by hot-plate welding. A glycidyl methacrylate (GMA) as a compatibilizing agent is copolymerized with methyl methacrylate Elium® resin. During the hot-tool welding process of dissimilar thermoplastic material, GMA can react with the polyamide end groups. The heat distribution at the Elium® GMA/PA-12 interface is responsible for obtaining a strong joint. This study focuses on the functionality of the compatibilizer on the welding of acrylic-based composites with polyamide (PA)-12 while varying the assembly temperature. The flatwise tensile test proved the effectiveness of GMA on the interface bounding. The excellent bounding incompatible polymers Elium® resin (PMMA) and PA12 was achieved at 200 °C.

Study on the application of 3D printing head film fixation technology in cranial radiotherapy.

Objective: To investigate the use of 3D printing technology to customize individualized precise radiotherapy head masks for cranial radiotherapy patients. Through the comparison with thermoplastic head film, evaluate the effect of this material on deep dose attenuation and body surface dose, and evaluate its positioning accuracy and repeatability for clinical application. Methods: Thirty patients with head and neck radiotherapy were divided into the control group and the experimental group. The control group used the traditional thermoplastic head film fixation technique for body position fixation, and the experimental group used the 3D printing head film fixation technique. The patient setup was verified by kV-CBCT scanning to obtain the translational setup error and rotational setup error in the X, Y, and Z directions. Results: At a depth of 5 cm, both materials have a radiation attenuation rate of <1%. At the surface location, the body surface dose of control group increased by approximately 27%. With a 3D printing head film, the body surface dose increased by approximately 18%. The positioning of two groups of patients was verified by the kV-CBCT, and a total of 232 data sets were obtained. The average translation positioning errors in the X, Y, and Z direction of control group and experimental group were 1.29 mm, 1.42 mm, 1.38 mm and 1.16 mm, 1.24 mm, 1.16 mm, respectively. The average rotation positioning error in the X, Y, and Z direction of control group and experimental group were 1.29°, 1.02°, 1.01° and 1.08°, 0.96°, 1.00°, respectively. The translational setup errors in the Y and Z directions and rotational setup errors in the X direction significantly differed between the control and experimental groups (all p<0.05), but no statistical significance was found in the other directions (all p>0. 05). Conclusion: Compared to the traditional thermoplastic head membranes, 3D printing head membranes has shown a reliable and reproducible interactional positioning accuracy. Of course, further investigations are needed before the new technology can be used on a regular basis.

The relationship between molecular structure and film-forming properties of thermoplastic starches from different botanical sources

To illustrate the correlations between molecular structures and the film-forming properties of thermoplastic starch from various botanical sources, starches from cereal, tuber and legume were modified by thermoplastic extrusion and the corresponding thermoplastic starch films were prepared including thermoplastic corn starch (TCS), thermoplastic rice starch (TRS), thermoplastic sweet potato starch (TSPS), thermoplastic cassava starch (TCAS) and thermoplastic pea starch (TPES) films. TPES film displayed a higher tensile strength (6.28 MPa) and stronger water resistance, such as lower water solubility (15.70 %), water absorption (42.35 %), and water vapor permeability (0.285 g·mm·h−1·m−2·kPa−1) due to higher contents of amylose and B1 chains. TCAS showed a smoother and more amorphous film due to higher amylopectin content, resulting higher elongation at break and larger opacity. TCS film was the most transparent due to a compacter network and more ordered crystallinity structure, which was suit for the packaging of fresh vegetables and aquatic products, whereas TCAS film was the opaquest, which protected package foods from light such as meat products, etc. The outcome would provide an innovative theory to regulate accurately the functional properties of thermoplastic starch films for different food needs.