Effect of Cotton Fiber Contents and Lengths on Properties of Thermoplastic Starch Composites Prepared from Rice and Waxy Rice Starches

Biodegradable polymer was prepared as thermoplastic starch (TPS) using rice and waxy rice starches. In order to increase mechanical properties and reduce water absorption of the TPS, cotton fiber was incorporated as the fiber reinforcement into the TPS matrix. The effect of cotton fiber contents and lengths on properties of the TPS was examined. Internal mixer and compression molding machine were used to mix and shape the samples. It was found that the thermoplastic rice starch (TPRS) showed higher stress at maximum load and Young’s modulus but lower strain at maximum load than the thermoplastic waxy rice starch (TPWRS). In addition, stress at maximum load and Young’s modulus of both TPRS and TPWRS increased significantly with the addition of the cotton fiber. Cotton fiber contents and lengths also affected mechanical properties of the TPRS and TPWRS composites. Moreover, water absorption of the TPRS and TPWRS composites decreased by the use of the cotton fibers. FT-IR and XRD techniques were used to study a change in functional group and crystallinity of the thermoplastic starch composites. Morphological, thermal and biodegradable properties of different thermoplastic starch composites were also investigated.     

Preparation and Properties of Green Composites Based on Tapioca Starch and Differently Recycled Paper Cellulose Fibers

Green composites obtained from biodegradable renewable resources have gained much attention due to environmental problems resulting from conventionally synthetic plastics and a global increasing demand for alternatives to fossil resources. In this work we used different cellulose fibers from used office paper and newspaper as reinforcement for thermoplastic starch (TPS) in order to improve their poor mechanical, thermal and water resistance properties. These composites were prepared by using tapioca starch plasticized by glycerol (30 % wt/wt of glycerol to starch) as matrix reinforced by the extracted cellulose fibers with the contents ranging from 0 to 8 % (wt/wt of fibers to matrix). Properties of composites were determined by mechanical tensile tests, differential scanning calorimetry, thermogravimetric analysis, water absorption measurements, scanning electron microscopy, and soil burial tests. The results showed that the introduction of either office paper or newspaper cellulose fibers caused the improvement of tensile strength and elastic modulus, thermal stability, and water resistance for composites when compared to the non-reinforced TPS. Scanning electron microscopy showed a good adhesion between matrix and fibers. Moreover, the composites biological degraded completely after 8 weeks but required a longer time compared to the non-reinforced TPS. The results indicated that these green composites could be utilized as commodity plastics being strong, inexpensive, plentiful and recyclable.     

Effects of Incorporating Polycaprolactone and Flax Fiber into Glycerol-Plasticized Pea Starch

This study focused on improving the material properties of pea thermoplastic starch (TPS) with polycaprolactone (PCL) and flax fiber. Accordingly, composites of glycerol-plasticized pea starch, polycaprolactone, and flax fiber were prepared through solid-phase compounding and compression-molding. The specimens were characterized through scanning electron microscopy, tensile test, moisture absorption test, and differential scanning calorimetry. Morphological studies of the tensile fracture surfaces revealed poor TPS-PCL interfacial interaction and limited TPS-flax fiber interfacial bonding. The composites showed significant improvements in tensile strength with reduced moisture absorption capability essentially due to the hydrophobicity of PCL. Individual components of the composites retained their respective thermal properties, an indication of thermodynamic immiscibility.     

Biodegradable Polyester-Based Blend Reinforced with Curauá Fiber: Thermal,Mechanical and Biodegradation Behaviour

Biodegradable composites can be produced by the combination of biodegradable polymers (BP) as matrix and vegetal fibers as reinforcement. Composites of a commercial biodegradable polymer blend and curauá fibers (loaded at 5, 15 and 20 wt%) were prepared by melt mixing in a twin-screw extruder. Chemical treatments such as alkali treatment of the fiber and addition of maleic anhydride grafted polypropylene (MA-g-PP) as coupling agent were performed to promote polymer/fiber interfacial adhesion so that mechanical performance can be improved. The resulting composites were evaluated through hardness, melt flow index and tensile, flexural and impact strengths as well as water absorption. Thermal analysis and Fourier transform infrared spectroscopy were also employed to characterize the composites. The polymer/fiber interface was investigated through scanning electron microscopy analysis. The biodegradability of composites was evaluated by compost-soil burial test. The addition of curauá fiber promoted an increase in the mechanical strengths and composites treated with 2 wt% MA-g-PP with 20 wt% curauá fiber showed an increase of nearly 75% in tensile and 56% in flexural strengths besides an improvement in impact strength with respect to neat polymer blend. Nevertheless, treated composites showed an increase in water absorption and biodegradation tests showed that the addition of fiber retards degradation time. The retained mass of BP/20 wt% fiber composite with MA-g-PP and neat BP was 68 and 26%, respectively, after 210 days of degradation test.     

Films Made by Blending Poly(ε-Caprolactone) with Starch and Flour from Sagu Rhizome Grown at the Venezuelan Amazons

Starch-based composite films have been proposed as food packaging. In this context, the study of non-conventional starch sources (sagu, Canna edulis Kerr) has worldwide special attention, because these materials can impart different properties as carbohydrate polymers. A thorough study of the matrices used (sagu starch and flour) was carried out. In the same way, thermoplastic starch (TPS)/PCL blend and thermoplastic flour (TFS)/PCL blend were obtained by melt mixing followed by compression moulding containing glycerol as plasticizer. In this study, chemical composition of the matrices and their properties were related with the properties of the developed films. Moisture content, water solubility, X-ray diffraction, thermogravimetric analysis and mechanical and microstructural properties were evaluated in the films. Taking into account the results, the sagu flour has great potential as starchy source for food packaging applications. However, concretely the flour had lower compatibility with the PCL compared to the starch/PCL blend.     

New Non-food-Based Composites of Acorn Nutlet and Polycaprolactone: Preparation and Characterization Evaluation

Two dissimilar renewable resource-based thermoplastic acorn nutlet (TPAN) materials were prepared via twin-screw extrusion with the aid of glycerol or monoethanolamine as plasticizers, and then two TPAN/polycaprolactone (PCL) composites with different plasticized systems were prepared. Mechanical test showed that glycerol-based composites had excellent tensile properties, and at a PCL content of 50 wt%, their tensile strength and elongation at break reached 14.4 MPa and 1,361 %, respectively. The micro-morphologic investigation of liquid-nitrogen brittle fracture surface indicated certain interface adhesion between glycerol-based thermoplastic acorn nutlet (GTPAN) and PCL. Dynamic mechanical thermal analysis , differential scanning calorimetry and thermogravimetric analysis demonstrated that the weight ratios of TPAN in composites significantly affected the crystallinity, glass transition temperature (T_g), melting temperature (T_m) and thermal stability of composites. Soil burial degradation analysis displayed that all composites had excellent biodegradability. These results demonstrated that GTPAN/PCL composites had superior mechanical and biodegradable properties, enough to partially replace the conventional thermoplastic plastics.     

Degradation of Polycaprolactone Modified with TPS or CaCO3 in Biotic/Abiotic Seawater

This paper is an investigation of the polymer degradation process in two types of seawater (with and without microorganisms) sourced from the Baltic Sea. The chosen polymeric materials were polycaprolactone modified with either thermoplastic starch (PCL/TPS?>?85%) or calcium carbonate (60% PCL/40% CaCO₃) compared directly against unmodified polycaprolactone. All samples were incubated for 28?weeks in seawater with and without microorganisms under laboratory conditions and analysed before and after the degradation process. Weight loss analysis, microscopic observations of polymer surfaces and tensile strength tests were used to determine the progress of polymer degradation. The experimental results obtained indicated, that in each of the experiments, degradation of tested polymeric samples occured. The process was more effective in seawater with microorganisms compared against systems without added microorganisms. The experiment in seawater demonstrated that modification of PCL with calcium carbonate did not encourage the degradation process; and in some circumstances inhibited it.     

Compatibilization Improves Performance of Biodegradable Biopolymer Composites Without Affecting UV Weathering Characteristics

With growing interest in the use of eco-friendly composite materials, biodegradable polymers and composites from renewable resources are gaining popularity for use in commercial applications. However, the long-term performance of these composites and the effect of compatibilization on their weathering characteristics are unknown. In this study, five types of biodegradable biopolymer/wood fiber (WF) composites were compatibilized with maleic anhydride (MA), and the effect of accelerated UV weathering on their performance was evaluated against composites without MA and neat biopolymers. The composite samples were prepared with 30 wt% wood fiber and one of the five biodegradable biobased polymer: poly(lactic) acid (PLA), polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Bioflex (PLA blend), or Solanyl (starch based). Neat and composite samples were UV weathered for 2000 h (hours), and characterized for morphological, physical, thermal, and mechanical properties before and after weathering. Compared to composites without MA, composites containing MA grafted polymers exhibited improved properties due to increased interfacial adhesion between the fiber and matrix. Upon accelerated weathering, thermal and mechanical properties of 70% of the samples substantially decreased. Surfaces of all the samples were roughened, and drastic color changes were observed. Water absorption of all the samples increased after weathering exposure. Even though the compatibilization is shown to improve composite properties before weathering, it did not affect weathering of samples, as there were no considerable differences in properties exhibited by the composites with MA and without MA after weathering. The results suggest that compatibilization improves properties of biodegradable biobased composites without affecting its UV degradation properties.     

Preliminary Testing of the Influence of Modified Polycaprolactones on Anabaena Variabilis Growth in Seawater

Several new biodegradable polymer materials have recently come onto the global market. Mostly the results on degradation kinetic studies are presented. This paper suggests using one of the tests to estimate the impact of polymer packaging material on sea life. The microorganism chosen was Anabaena variabilis (identified in many waters, including those of the Baltic Sea, especially in the Gulf of Gdańsk and Puck Bay; this cyanobacterium has a tendency to move with deep-sea waters causing algal blooms that upset the ecological balance of the marine environment [1]). The chosen polymer materials were polycaprolactone modified with thermoplastic starch (PCL/TPS > 85%) or with calcium carbonate (60% PCL/40% CaCO₃). They were incubated in seawater in the presence of A. variabilis. The chlorophyll a content was determined as the criterion of cyanobacterial growth in the presence of the tested polymers. The polymer surface and colour changes in the cyanobacterium culture were recorded photographically. The experimental results indicate that the addition of polymer samples to the cyanobacterium culture affects its biological balance. During the experiment in seawater, cyanobacteria adhered to the polymer surfaces and their growth was stimulated to different degree by the polymers. Thus, the suggested test differentiate the behaviour of both materials studied. Cyanobacterial growth was lower in the presence of PCL modified with calcium carbonate than in the presence PCL/TPS blend.     

Biodegradability and Thermal Properties of Novel Natural Rubber/Linear Low Density Polyethylene/Thermoplastic Starch Ternary Blends

This work aimed to prepare biodegradable thermoplastic elastomers based on NR/LLDPE/TPS ternary simple blends to achieve some exclusive properties, i.e., good biodegradability in terms of water absorption and weight loss after burial, together with reasonable mechanical and thermal properties. A comparative study on biodegradability and other related properties of NR/LLDPE binary and NR/LLDPE/TPS ternary blends was performed. It was found that increasing the TPS proportion decreased storage modulus and complex viscosity. In addition, the size of dispersed TPS domains in the NR/LLDPE co-continuous matrix increased with TPS proportion, while the mechanical properties in terms of 100% moduli, tensile strength, elongation at break, and hardness decreased. This might be attributed to decreased interfacial adhesion with increasing size of TPS domains. Furthermore, increasing the TPS loading in the blend reduced the temperatures for 5 or 50% mass loss (T₅ or T₅₀) and the degradation temperature (T _d ). However, the biodegradability improved, in terms of increased water absorption and weight loss after burial in soil, with the loading level of TPS.     

Fiber from DDGS and Corn Grain as Alternative Fillers in Polymer Composites with High Density Polyethylene from Bio-based and Petroleum Sources

The steady increase in production of corn based ethanol fuel has dramatically increased the supply of its major co-product known as distiller’s dried grain with solubles (DDGS). Large amount of DDGS and corn flour are used as an animal feed. The elusieve process can separate DDGS or corn flour into two fractions: DDGS fraction with enhanced protein and oil content or corn flour fraction with high starch content, and hull fiber. This study investigated the feasibility of using fiber from DDGS and corn grain as alternative fillers to wood fiber in high density polyethylene (HDPE) composites made with two different sources of polymers. Two fiber loading rates of 30 and 50% were evaluated for fiber from DDGS, corn, and oak wood (control) to assess changes in various physical and mechanical properties of the composite materials. Two HDPE polymers, a bio-based HDPE made from sugarcane (Braskem), and a petroleum based HDPE (Marlex) were also compared as substrates. The biobased polymer composites with DDGS and corn fibers showed significantly lower water absorption than the Marlex composite samples. The Braskem composite with 30% DDGS fiber loading showed the highest impact resistance (80 J/m) among all the samples. The flexural properties showed no significant difference between the two HDPE composites.     

Physical properties and biodegradability of blends containing poly(ε-caprolactone) and tropical starches

In order to assess feasibility of tropical starches (sago and cassava starches) as biodegradable plastic materials, blending with poly(-caprolactone) (PCL), a biodegradable polymer, was carried out. It was confirmed that the physical properties (tensile strength and elongation) of PCL/sago and PCL/cassava blends were similar to those of PCL/corn blend, suggesting that sago and cassava starches can also be blended with PCL for production of biodegradable plastic. However, the properties of all PCL/starch blends were still low compared with those of polyethylene. Enzymatic degradability evaluation showed that lipase degradation of PCL and-amylase degradation of starch increased as the starch content in the blend increased. Burial test of the blends for 1, 3, and 5 months was carried out and the rate of degradation of the PCL/sago blend was confirmed to be slower than those of PCL/corn and PCL/cassava blends. Observation of the film blends structure by scanning electron microscope revealed that the starch was dispersed in a PCL continuous phase. Furthermore, changes in the film surface before and after enyzme treatments were observed.     

Natural Fiber Reinforced Poly(vinyl chloride) Composites: Effect of Fiber Type and Impact Modifier

Poly(vinyl chloride) (PVC) and natural fiber composites were prepared by melt compounding and compression molding. The influence of fiber type (i.e., bagasse, rice straw, rice husk, and pine fiber) and loading level of styrene-ethylene-butylene-styrene (SEBS) block copolymer on composite properties was investigated. Mechanical analysis showed that storage modulus and tensile strength increased with fiber loading at the 30% level for all composites, but there was little difference in both properties among the composites from various fiber types. The use of SEBS decreased storage moduli, but enhanced tensile strength of the composites. The addition of fiber impaired impact strength of the composites, and the use of SEBS led to little change of the property for most of the composites. The addition of fiber to PVC matrix increased glass transition temperature (T_g), but lowered degradation temperature (T_d) and thermal activation energy (E_a). After being immersed in water for four weeks, PVC/rice husk composites presented relatively smaller water absorption (WA) and thickness swelling (TS) rate compared with other composites. The results of the study demonstrate that PVC composites filled with agricultural fibers had properties comparable with those of PVC/wood composite.     

Characterization of Extruded Thermoplastic Starch Reinforced by Montmorillonite Nanoclay

The purpose of this study was to understand how the montmorillonite (MMT) nanoclay influences physical and mechanical properties of thermoplastic starch (TPS), which was produced by a conventional extrusion procedure. MMT nanoclay was added at 0, 4, and 8 % (w/w) concentrations. Transmission electron microscopy (TEM) showed most MMT platelets existed in tactoid structure in the starch matrix. In addition, FTIR spectra indicated TPS/MMT nanocomposites kept chemically stable after the extrusion. Tensile strength (TS) was about 7.0 MPa, while elongation-at-break (E) and elastic modulus (EM) were about 52 % and 32–41 MPa, respectively. Moisture sorption behaviour of the samples was well described by GAB and BET models. Thermal property tests exhibited the glass transition temperature (T _g ) of the nanocomposites decreased with increasing MMT from 0 to 8 %, indicating MMT nanoclay had a plasticization effect.     

Potential of <Emphasis Type="Italic">pinhão</Emphasis> Coat as Constituents of Starch Based Films Using Modification Techniques

The potential of lignocellulosic fibers obtained by dry grinding of pinhão coat as fillers in starch filmogenic solutions for packaging applications was evaluated in this work. To improve the incorporation of this waste into the starch solutions different physical and chemical treatments were conducted. Thereafter, morphology, chemical structure, crystallinity and water absorption of the pinhão coat powders were determined. The composites were also characterized regarding their morphology, chemical structure, crystallinity, mechanical properties, water vapor permeability and hydrophilicity. Poor fiber/matrix adhesion and high water absorption of the fibers were evidenced. Consequently, water vapor permeability of composites was increased by incorporating the fibers. Moreover, mechanical properties were improved and the morphological results were used to support the water absorption differences among the powders. Regarding the food packaging applications, starch/pinhão coat composites appeared as promising materials to reach the requirements of respiring food products.     

Effects of Alkali Treatment on the Properties of Short Flax Fiber–Poly(Lactic Acid) Eco-Composites

In this study, the influence of alkali (NaOH) treatment on the mechanical, thermal and morphological properties of eco-composites of short flax fiber/poly(lactic acid) (PLA) was investigated. SEM analysis conducted on alkali treated flax fibers showed that the packed structure of the fibrils was deformed by the removal non-cellulosic materials. The fibrils were separated from each other and the surface roughness of the alkali treated flax fibers was improved. The mechanical tests indicated that the modulus of the untreated fiber/PLA composites was higher than that of PLA; on the other hand the modulus of alkali treated flax fiber/PLA was lower than PLA. Thermal properties of the PLA in the treated flax fiber composites were also affected. T_g values of treated flax fiber composites were lowered by nearly 10 °C for 10% NaOH treatment and 15 °C for 30% NaOH treatment. A bimodal melting behavior was observed for treated fiber composites different than both of neat PLA and untreated fiber composites. Furthermore, wide angle X-ray diffraction analysis showed that the crystalline structure of cellulose of flax fibers changed from cellulose-I structure to cellulose-II.     

Mechanical Properties of Poly (Lactic Acid)/Hemp Fiber Composites Prepared with a Novel Method

This research dealt with a novel method of fabricating green composites with biodegradable poly (lactic acid) (PLA) and natural hemp fiber. The new preparation method was that hemp fibers were firstly blending-spun with a small amount of PLA fibers to form compound fiber pellets, and then the traditional twin-screw extruding and injection-molding method were applied for preparing the composites containing 10–40 wt% hemp fibers with PLA pellets and compound fiber pellets. This method was very effective to control the feeding and dispersing of fibers uniformly in the matrix thus much powerful for improving the mechanical properties. The tensile strength and modulus were improved by 39 and 92 %, respectively without a significant decrease in elongation at break, and the corresponding flexural strength and modulus of composites were also improved by 62 and 90 %, respectively, when the hemp fiber content was 40 wt%. The impact strength of composite with 20 wt% hemp fiber was improved nearly 68 % compared with the neat PLA. The application of the silane coupling agent promoted further the mechanical properties of composites attributed to the improvement of interaction between fiber and resin matrix.     

Preparation and Properties of Thermoplastic Starch/Montmorillonite Nanocomposite Using N-(2-Hydroxyethyl)formamide as a New Additive

N-(2-Hydroxyethyl)formamide (HF) was synthesized efficiently and used as a new additive to prepare thermoplastic starch/montmorillonite nanocomposite (TPS/MMT). Here, HF acted as both plasticizer for TPS and swelling agent for MMT. The hydrogen bond interaction among HF, starch and MMT was proven by Fourier-transform infrared (FT-IR) spectroscopy. By scanning electron microscope (SEM), starch granules were completely disrupted. Atomic force microscopy demonstrated that partially exfoliated TPS/MMT nanocomposite was formed. The crystallinity of corn starch, MMT, HF-plasticized TPS (HTPS) and TPS/MMT nanocomposite was characterized by X-ray diffraction (XRD). Thermal stability of HTPS and TPS/MMT was determined by thermogravimetric analysis (TGA). The water resistance of TPS/MMT nanocomposite increased compared with that of pure HTPS. Tensile strengths of TPS/MMT nanocomposites were higher than those of HTPS, but just the reverse for elongations at break.     

Poly(Ethylene Glycol) as a Compatibilizer for Poly(Lactic Acid)/Thermoplastic Starch Blends

A new route to prepare poly(lactic acid) (PLA)/thermoplastic starch (TPS) blends is described in this work using poly(ethylene glycol) (PEG), a non-toxic polymer, as a compatibilizer. The influence of PEG on the morphology and properties of PLA/TPS blends was studied. The blends were processed using a twin-screw micro-compounder and a micro-injector. The morphologies were analyzed by scanning and transmission electron microscopies and the material properties were evaluated by dynamic-mechanical, differential scanning calorimetry, thermogravimetric analysis and mechanical tests. PLA/TPS blends presented large TPS phase size distribution and low adhesion between phases which was responsible for the lower elastic modulus of this blend when compared to pure PLA. The addition of PEG resulted in the increase of PLA crystallization, due to its plasticizing effect, and improvement of the interfacial interaction between TPS and PLA matrix. Results show that incorporation of PEG increased the impact strength of the ternary blend and that the elastic modulus remained similar to the PLA/TPS blend.     

Effects of Compatibilizer and Thermoplastic Starch (TPS) Concentration on Morphological,Rheological, Tensile,Thermal and Moisture Sorption Properties of Plasticized Polylactic Acid/TPS Blends

The blends of polylactic acid plasticized with acetyl tributyl citrate (P-PLA) and thermoplastic wheat starch (TPS) were prepared by a co-rotating twin screw extruder and the effect of maleic anhydride grafted PLA (PLA-g-MA) content as reactive compatibilizer on blends compatibility through morphological, rheological and tensile properties of the blends was investigated. Considerable improvement in properties of P-PLA/TPS (70/30 w/w) blend with incorporating the optimum PLA-g-MA content of 4 phr was achieved as this blend exhibited better morphological and rheological properties with an increase by 158 and 276% in tensile strength and elongation at break, respectively, compared to the uncompatibilized blend. Also the thermal stability and moisture sorption properties of the blends as effected by TPS content were studied. Decreasing in thermal stability and increasing in equilibrium moisture content of the blends were observed with progressively increasing of TPS content. For prediction the moisture sorption behaviour of blends with various TPS contents at different relative humidity, the moisture sorption isotherm data were modeled by GAB (Guggenheim–Anderson–de Boer) model.