scholarly journals Thermoplastic Starch-Based Blends with Improved Thermal and Thermomechanical Properties

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4263
Author(s):  
Anayansi Estrada-Monje ◽  
Sergio Alonso-Romero ◽  
Roberto Zitzumbo-Guzmán ◽  
Iván Alziri Estrada-Moreno ◽  
Erasto Armando Zaragoza-Contreras
Keyword(s):  
Tensile Strength ◽  
Corn Starch ◽  
Thermoplastic Starch ◽  
Cassava Starch ◽  
Thermomechanical Properties ◽  
Hydroxyl Groups ◽  
Carbonyl Groups ◽  
Short Term ◽  
Absorption Bands

This research focused on the development of biomaterials based on cassava starch and corn starch and on the effect of the incorporation of polycaprolactone (PCL) on the thermal and thermomechanical properties of the blends. The results indicated partial compatibility in the blends, especially with cassava starch at a content of 20 wt% as reflected by the maintenance of tensile strength and elongation. In addition, the changes in the crystal quality of PCL and the displacement of the absorption bands of the carbonyl groups of PCL in the infrared (989–1000 cm−1), attributed to the formation of hydrogen bonds between these groups and the hydroxyl groups of starches, were also associated with compatibility. It was observed that the crystallinity of PLC in the presence of cassava and corn starch was 38% and 62%, respectively; a crystallinity greater than that of PCL was related to an improved nucleation at the interface. Based on these properties, the blends are expected to be functional for the manufacture of short-term use products by conventional thermoplastic processing methods.

scholarly journals Biocomposite of Cassava Starch Reinforced with Cellulose Pulp Fibers Modified with Deposition of Silica (SiO2) Nanoparticles

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Joabel Raabe ◽  
Alessandra de Souza Fonseca ◽  
Lina Bufalino ◽  
Caue Ribeiro ◽  
Maria Alice Martins ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Sol Gel ◽  
Fiber Surface ◽  
Sio2 Nanoparticles ◽  
Thermoplastic Starch ◽  
Cassava Starch ◽  
Sem Analysis ◽  
Pulp Fibers ◽  
Moisture Adsorption ◽  
Cellulose Pulp

Eucalyptuspulp cellulose fibers were modified by the sol-gel process for SiO2superficial deposition and used as reinforcement of thermoplastic starch (TPS). Cassava starch, glycerol, and water were added at the proportion of 60/26/14, respectively. For composites, 5% and 10% (by weight) of modified and unmodified pulp fibers were added before extrusion. The matrix and composites were submitted to thermal stability, tensile strength, moisture adsorption, and SEM analysis. Micrographs of the modified fibers revealed the presence of SiO2nanoparticles on fiber surface. The addition of modified fibers improved tensile strength in 183% in relation to matrix, while moisture adsorption decreased 8.3%. Such improvements were even more effective with unmodified fibers addition. This result was mainly attributed to poor interaction between modified fibers and TPS matrix detected by SEM analysis.

Effect of Co60γ Ray Irradiation on Thermoplastic Corn Starch Plastic

2013 ◽  
Vol 772 ◽  
pp. 34-37
Author(s):  
Hao Tang ◽  
Hai Tian Jiang ◽  
Bin Guo ◽  
Pan Xin Li
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Corn Starch ◽  
Irradiation Time ◽  
Thermoplastic Starch ◽  
Endothermic Peak ◽  
Macromolecular Structure ◽  
Thermal And Mechanical Properties ◽  
Elongation At Break ◽  
Γ Ray

Corn starch was irradiated by 60Coγ ray, and then the thermoplastic starch plastic (TPS) was prepared by adding glycerol. Microstructure, thermal and mechanical properties of the corn starch and starch plastic were studied in details by FTIR, DSC and SEM. Results showed that the starch macromolecular structure was damaged by irradiation, and with increased irradiation time, the temperature of melt endothermic peak and tensile strength decreased, elongation at break increases for starch plastic, the thermoplastic property of starch was enhanced obviously.

scholarly journals Pine Resin Derivatives as Sustainable Additives to Improve the Mechanical and Thermal Properties of Injected Moulded Thermoplastic Starch

2020 ◽  
Vol 10 (7) ◽  
pp. 2561 ◽  
Author(s):  
Miguel Aldas ◽  
Cristina Pavon ◽  
Juan López-Martínez ◽  
Marina Patricia Arrieta
Keyword(s):  
Corn Starch ◽  
Mechanical Performance ◽  
Thermoplastic Starch ◽  
Dehydroabietic Acid ◽  
Hydroxyl Groups ◽  
Mechanical And Thermal Properties ◽  
Pine Resin ◽  
Pentaerythritol Ester ◽  
Hydrogen Bond Interactions ◽  
Gum Rosin

Fully bio-based materials based on thermoplastic starch (TPS) were developed starting from corn starch plasticized with glycerol. The obtained TPS was further blended with five pine resin derivatives: gum rosin (GR), disproportionated gum rosin (dehydroabietic acid, RD), maleic anhydride modified gum rosin (CM), pentaerythritol ester of gum rosin (LF), and glycerol ester of gum rosin (UG). The TPS–resin blend formulations were processed by melt extrusion and further by injection moulding to simulate the industrial conditions. The obtained materials were characterized in terms of mechanical, thermal and structural properties. The results showed that all gum rosin-based additives were able to improve the thermal stability of TPS, increasing the degradation onset temperature. The carbonyl groups of gum rosin derivatives were able to interact with the hydroxyl groups of starch and glycerol by means of hydrogen bond interactions producing a significant increase of the glass transition temperature with a consequent stiffening effect, which in turn improve the overall mechanical performance of the TPS-resin injected moulded blends. The developed TPS–resin blends are of interest for rigid packaging applications.

Effect of wheat straw oxidation on thermoplastic starch composites: Mechanical, thermal, and rheological process behaviors

2018 ◽  
Vol 33 (5) ◽  
pp. 646-658 ◽  
Author(s):  
Yin Peng ◽  
Dongdong Zha ◽  
Guo Bin ◽  
Li Bengang ◽  
Li Panxin
Keyword(s):  
Tensile Strength ◽  
Wheat Straw ◽  
Corn Starch ◽  
Sodium Periodate ◽  
Thermoplastic Starch ◽  
Mechanical And Thermal Properties ◽  
Elongation At Break ◽  
Torque Measurements ◽  
Natural Filler ◽  
Scanning Electron

The objective of this work is to evaluate the reinforced effect of wheat straw (WS) after oxidation in thermoplastic corn starch (TPS).The mechanical properties (tensile strength and elongation at break) of TPS and oxidized wheat straw (OWS)/TPS composites were evaluated by the tensile measurements. The composites were characterized further using scanning electron microscopy (SEM), dynamic mechanical thermal analysis, and torque measurements. In general, OWS played a key role for enhanced mechanical and thermal properties in composites, and the composites had slightly poorer rheological processing behaviors, compared to the TPS. The highest tensile strength (7.66 MPa) was achieved using WS oxidized with 0.045 mol·L−1 sodium periodate. The damage and erosion produced on WS after oxidation positively affected the properties of the composites. With respect to the findings of this study, it may be stated that OWS can be used as a promising natural filler for other composites.

scholarly journals Effect of Alkali Treatment on Structure and Properties of High Amylose Corn Starch Film

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1705 ◽  
Author(s):  
Yang Qin ◽  
Hui Zhang ◽  
Yangyong Dai ◽  
Hanxue Hou ◽  
Haizhou Dong
Keyword(s):  
Tensile Strength ◽  
Sodium Hydroxide ◽  
Corn Starch ◽  
Film Formation ◽  
Alkali Treatment ◽  
Hydroxyl Groups ◽  
Elongation At Break ◽  
Naoh Treatment ◽  
High Amylose ◽  
Starch Molecule

Alkali treatment is used for melt extrusion film formation with corn starch, but optimal conditions for this procedure are still unknown. In this study, the changes in properties and structure of high amylose corn starch (70%) films with different concentrations of sodium hydroxide (NaOH), prepared by melting extrusion, were investigated. With increasing sodium hydroxide concentrations, the tensile strength of the high-amylose starch film decreased gradually, while the elongation at break increased. The tensile strength of the high amylose starch (HAS) film with 2% NaOH-treatment was 10.03 MPa and its elongation at break was 40%. A 2% NaOH-treatment promoted the orderly rearrangement of starch molecules and formed an Eh-type crystal structure, which enlarged the spacing of the single helix structure, increased the molecular mobility of the starch, and slowed down the process of recrystallization; a 10% NaOH-treatment oxidized the hydroxyl groups of the high amylose corn starch during extrusion, formed a poly-carbonyl structure, and initiated the degradation and cross-linking of starch molecule chains.

Photo-Oxidation of an IR Vulcanizate

1981 ◽  
Vol 54 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Shoichiro Yano
Keyword(s):  
Ir Spectra ◽  
Rate Constant ◽  
Wavelength Dependence ◽  
The Other ◽  
Hydroxyl Groups ◽  
Carbonyl Groups ◽  
Absorption Bands ◽  
Photo Oxidation ◽  
Other Hand ◽  
Uv And Ir Spectra

Abstract On irradiation with uv light, changes in uv and ir spectra were observed. In the uv spectrum, a minimum at 290 nm due to sulfur, dibenzothiazyl disulfide, and double bonds in the main chains disappeared initially by the consumption of them; but the minimum reappeared on further irradiation reflecting the formation of carbonyl groups. On the other hand, in the ir spectrum two absorption bands appeared at 1720 cm−1 (due to carbonyl groups) and 3450 cm−1 (due to hydroxyl groups). The latter band faded out suggesting the decomposition of hydroperoxides when the vulcanizate was kept in the dark after irradiation. From the findings of the wavelength dependence of photo-oxidation on uv and ir spectra, it was found that the degradation occurred below about 430 nm. However, investigation of the wavelength dependence of photo-oxidation by the measurement of the crosslink density gave the results that crosslinking reactions occurred below about 340 nm, scissions of C-C and polysulfide crosslinks between 340 and about 400 nm, and scissions of polysulfide crosslinks between 400 and 600 nm. These were confirmed by measurements of the dynamic modulus during irradiation. The relative modulus E′(t)/E′(0) increased on irradiation with light at 253.7 nm in a longer time region reflecting a crosslinking reaction. On the other hand, on irradiation with light above 330 nm, E′(t)/E′(0) decreased with time. Change in E′(t)/E′(0) could be represented by the equation of the first order reaction containing an exponential term and the rate constant was determined. The activation energy was calculated as 18.6 kcal/mole from the temperature dependence of the rate constant and agreed with that for scission of polysulfide crosslinks. The photodegradation of the IR vulcanizate occurred also on irradiation with visible light (> 430 nm), and the modulus decreased.

Investigation of Thermoplastic Starch/Fiber Blend: Effect of Tapioca Residue on the Mechanical Properties and Surface Study

2017 ◽  
Vol 873 ◽  
pp. 123-127
Author(s):  
Yupawan Thongjun ◽  
Thiti Kaisone ◽  
Pran Hanthanon ◽  
Chanon Wiphanurat ◽  
Sumate Ouipanich ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polymer Matrix ◽  
Corn Starch ◽  
Thermoplastic Starch ◽  
Compression Molding ◽  
Reinforcing Effect

The aim of this study was to characterize thermoplastic starch containing corn starch and tapioca residues, which were used as reinforcement in a blended matrix. In the process, the composites were prepared with different tapioca residue contents at 20, 30, 40, 50 and 60 % by weight using compression molding at 135 °C for 8 min. Subsequently, their mechanical, thermal and morphology properties were evaluated. The results showed that the reinforcing effect of tapioca residue lead an increase in the stiffness of the samples. Young’s modulus increased with higher tapioca residue content. When the loading of tapioca residue increased tensile strength for 80/20 and 70/30 mixtures from 7.46 to 8.58 MPa. In addition to the highest of tapioca residue could increase tensile strength dramatically. Further, the glass transition temperature tended to decrease with the increased loading of tapioca residue. Moreover, the morphology showed that the increment of tapioca residue content appeared embedded in the polymer matrix.

Effect of Cassava Starch Destructuration to Mechanical Properties of Compostable Blends

2011 ◽  
Vol 337 ◽  
pp. 159-162 ◽  
Author(s):  
Roung Rong Thongtan ◽  
Klana Rong Sriroth
Keyword(s):  
Mechanical Properties ◽  
Water Sorption ◽  
Starch Granule ◽  
Free Water ◽  
Thermoplastic Starch ◽  
Cassava Starch ◽  
Poly Lactic Acid ◽  
Hydroxyl Groups ◽  
Free Hydroxyl ◽  
Pregelatinized Starch

Pregelatinized and oxidized cassava starches were proven to be satisfactory to be distributed into poly(lactic acid) and poly(butylene adipate-co-terephthalate) mixture in order to obtain relatively inexpensive compostable material with acceptable properties. Thermoplastic starch from cassava appeared to effectively plasticize the mixture, particularly by pregelatinized starch which underwent complete granular destructuration. The destructuration allowed free hydroxyl groups in starch molecules to bind with free water and resulted in larger free volume which enhanced molecular mobility and, hence, the elongation. However, the destructuration of starch granule accelerated the dissolution of material in water and enhanced water sorption into the blend material.

Cathartic Effect of Suicide Attempts Not Limited to Depression

Crisis ◽  
2003 ◽  
Vol 24 (2) ◽  
pp. 73-78 ◽  
Author(s):  
Yves Sarfati ◽  
Blandine Bouchaud ◽  
Marie-Christine Hardy-Baylé
Keyword(s):  
Quality Of Life ◽  
Depressive Symptoms ◽  
Personality Traits ◽  
Rating Scales ◽  
Suicide Attempts ◽  
World Health ◽  
Life Questionnaire ◽  
Short Term

Summary: The cathartic effect of suicide is traditionally defined as the existence of a rapid, significant, and spontaneous decrease in the depressive symptoms of suicide attempters after the act. This study was designed to investigate short-term variations, following a suicide attempt by self-poisoning, of a number of other variables identified as suicidal risk factors: hopelessness, impulsivity, personality traits, and quality of life. Patients hospitalized less than 24 hours after a deliberate (moderate) overdose were presented with the Montgomery-Asberg Depression and Impulsivity Rating Scales, Hopelessness scale, MMPI and World Health Organization's Quality of Life questionnaire (abbreviated versions). They were also asked to complete the same scales and questionnaires 8 days after discharge. The study involved 39 patients, the average interval between initial and follow-up assessment being 13.5 days. All the scores improved significantly, with the exception of quality of life and three out of the eight personality traits. This finding emphasizes the fact that improvement is not limited to depressive symptoms and enables us to identify the relative importance of each studied variable as a risk factor for attempted suicide. The limitations of the study are discussed as well as in particular the nongeneralizability of the sample and setting.

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