3,316 research outputs found

    Effect of Potato Starch on Thermal & Mechanical Properties of Low Density Polyethylene

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    Recent Advances in Starch-Based Blends and Composites for Bioplastics Applications

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    Environmental pollution by synthetic polymers is a global problem and investigating substitutes for synthetic polymers is a major research area. Starch can be used in formulating bioplastic materials, mainly as blends or composites with other polymers. The major drawbacks of using starch in such applications are water sensitivity and poor mechanical properties. Attempts have been made to improve the mechanical properties of starch-based blends and composites, by e.g., starch modification or plasticization, matrix reinforcement, and polymer blending. Polymer blending can bring synergetic benefits to blends and composites, but necessary precautions must be taken to ensure the compatibility of hydrophobic polymers and hydrophilic starch. Genetic engineering offers new possibilities to modify starch inplanta in a manner favorable for bioplastics applications, while the incorporation of antibacterial and/or antioxidant agents into starch-based food packaging materials brings additional advantages. In conclusion, starch is a promising material for bioplastic production, with great potential for further improvements. This review summarizes the recent advances in starch-based blends and composites and highlights the potential strategies for overcoming the major drawbacks of using starch in bioplastics applications

    Mechanical Properties of Potato- Starch Linear Low Density Polyethylene Blend

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    The mechanical properties of potato-starch filled LLDPE such as Young’s Modulus, tensile strength and elongation at break were studied. Apart from the Young’s Modulus, the tensile strength and elongation at break reduced with increased starch content. This is attributed to poor adhesion between starch and the polymer matrix. The mechanical properties however, conform to Kerner’s and Nielson’s models with very minimal deviations.Keywords: Young’s Modulus, elongation at break, Kerner’s and Nielson’s Composite Models, LLDP

    Evaluation of zwitterionic starch filler in thermoset polyurethanes on the antithrombogenicity activity as candidates for cardiovascular applications

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    90 páginasCardiovascular diseases have increased worldwide due to post complications generated by SARS-Cov-2 illness, and bad food habits settled after quarantine suffered from this situation. In this context, demand for vascular grafts has increased because these devices are used to solve obstructions of blood vessels. However, the autologous graft availability is low and synthetic materials used for these cardiovascular devices have shown low thromboresistance over frame time. Polyurethanes implemented in this field have shown good mechanical properties and biocompatibility. Nevertheless, thrombogenicity activity is high yet in comparison with autologous graft. Some efforts as surface, chemical backbone modifications and inclusion of fillers in polyurethanes have shown an improvement in anti-thrombogenicity activity in the short term, but this increase in this activity did not remain over the years. In the last years, zwitterionic moieties have been a tendency due to their anti-fouling properties, which prevent no-specific adsorption protein and the activation of cascade coagulation. These moieties have been included at the surface and inside the chemical backbone of polyurethanes. However, the inclusion of these compounds at the surface did not stay over time due to the shear force caused by blood flow. Additionally, the chemical modification of polyurethanes affects their mechanical properties to a significant degree. Therefore, this research studied the influence of addition potato and zwitterionic starch (at 1, 2 and 3%w/w) as fillers in polyurethane matrices obtained from polycaprolactone diol (PCL), polyethylene glycol (PEG), pentaerythritol (PE), and isophorone diisocyanate (IPDI) on their physicochemical, mechanical thermal, and biological properties.Maestría en Diseño y Gestión de ProcesosMagíster en Diseño y Gestión de Proceso

    Gelatinized and nongelatinized starch/pp blends : effect of starch source and carboxylic and incorporation

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    Due to the environmental impact caused by incorrect disposal and the non-biodegradability of synthetic polymers, the packaging sector seeks renewable raw materials. An alternative is the utilization of natural renewable polymer, such as thermoplastic starch (TPS), mixed with synthetics. However, the chemical incompatibility between these two materials leads to the use of a compatibilizer agent. Even though the compatibilizer effect of carboxylic acid on TPS blends have been studied, the correlation between the carboxylic acid and the starch source has not been investigated yet. Thus, this study focuses on the effects of added carboxylic acids (myristic (C14) and stearic (C18) acid) and the starch sources (corn, cassava, and potato) on the properties and microstructure of blends with TPS/PP (70/30). The results suggested that the compatibilizer effect of acids depends on the starch source and the length of the acid chain, where cassava blends with C14 showed better results. Acid insertion increased tensile strength and deformation at break, but reduced the elastic modulus, indicating a plasticizer effect. This behavior was related to the formation of amylose and lipid complexes (endogenous or added) during heating. Torque reduction and Tg displacement were also observed for acid blends. The SEM images showed two different morphological dispersions and a non-gelatinization effect due to the acid insertion. Results suggested that acids act differently according to the starch source

    Faktor-faktor yang mempengaruhi pelajar wanita dalam memilih bidang kejuruteraan awam, elektrik dan mekanikal sebagai suatu kerjaya masa hadapan

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    Kajian ini bertujuan untuk mengenalpasti hubungan di antara empat faktor iaitu minat, keiuarga, w/ e woae/ dan jangkaan gaji dengan peiajar wanita daiam memiiih bidang kejuruteraan sebagai suatu kerjaya masa hadapan. Seramai 150 peiajar terdiri daripada peiajar-peiajar Semester Satu Sarjana Muda Kejuruteraan Awam, Elektrik dan Mekanika! bagi sesi 2001/2002 teiah dijadikan sampe! kajian. Data dikumpui dengan menggunakan set soai selidik dan dianahsis menggunakan program &ar/A//ca/ Packageyor r/ze &c/a / ^c/gncgy (SPSS 10.0 for Windows). Ujian pekaii Korelasi Spearman rho telah digunakan untuk mengenalpasti hubungan di antara pembolehubah-pemboiehubah. Hasii kajian menunjukkan keempat-empat faktor iaitu minat, keiuarga, w/ e nwae/ dan jangkaan gaji mempunyai hubungan yang signifikan dengan pelajar. Faktor minat menunjukkan r = 0.997, p < 0.01 (Awam), r = 0.996, p < 0.01 (Eiektrik) dan r = 0.994, p < 0.01 (Mekanika!). Bagi faktor keiuarga pula, ketiga-tiga program menunjukkan r = 0.996, p < 0.01. Manakaia faktor ro/e mooe/, Awam menunjukkan r = 0.999, p < 0.01, Elektrik r = 0.998, p < 0.01 dan Mekanika) r = 0.988, p < 0.01 dan bagi faktor jangkaan gaji, Awam menunjukkan r = 0.999, p < 0.01, Elektrik r = 0.999, p < 0.01 dan Mekanika) r = 0.995, p < 0.01. Oleh yang demikian, keempat-empat faktor tersebut perluiah memainkan peranan masing-masing bagi mempertingkatkan penyertaan kaum wanita daiam iapangan kejuruteraan

    Effects of incorporating polycaprolactone and flax fiber into glycerol-plasticized pea starch

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    The environmental menace associated with the existing eco-unfriendly conventional plastics prompted the exploration of natural polymers such as starch for the development of biodegradable plastics. These efforts have seen starch used in various ways, one of which is in the processing of thermoplastic starch (TPS). Thermoplastic starch (also known as plasticized starch) is the product of the interaction between starch and a plasticizer in the presence of thermomechanical energy. While starch blends with conventional plastics only yield products that biofragment, thermoplastic starch (TPS) offers a completely biodegradable option. However, it is limited in application due to its weak mechanical strength and poor moisture resistance. To this end, the objective of this study was to determine the effects of incorporating polycaprolactone (PCL) and flax fiber into glycerol-plasticized pea starch. The effects of processing moisture content on the physical properties of glycerol-plasticized pea starch were also evaluated. The physical properties investigated included morphology, tensile properties, moisture absorption, and thermal properties. Accordingly, two thermoplastic pea starch mixtures containing 9.3 and 20% processing moisture contents were prepared while maintaining starch (pea starch) and glycerol in ratio 7:3 by weight (dry basis). Polycaprolactone was then compounded at 0, 10, 20, 30, and 40% by weight in the solid phase with the TPS mixtures to determine the effects of processing moisture content and PCL incorporation on the physical properties of glycerol-plasticized pea starch. This experiment was structured as a 2 x 5 factorial completely randomized design at 5% level of significance. Subsequently, PCL and flax fiber were compounded with the TPS mixture containing 20% processing moisture to determine the effects of PCL (0, 20, and 40% wt) and flax fiber (0, 5, 10, and 15% wt) incorporation on the physical properties of glycerol-plasticized pea starch. This was structured as a 3 x 4 factorial completely randomized design at 5% level of significance. All the samples were compressed at 140°C for 45 min under 25000-kg load. The compression-molded samples were characterized using scanning electron microscopy (SEM), tensile test, moisture absorption test, and differential scanning calorimetry (DSC) techniques. The tensile fracture surfaces showed a moisture-induced fundamental morphological difference between the two TPSs. The TPS prepared at 20% processing moisture content revealed complete starch gelatinization, thus, exhibiting a rather continuous phase whereas the TPS prepared at 9.3% processing moisture content revealed instances of ungelatinized and partly gelatinized pea starch granules. Consequently, the tensile strength, yield strength, Young’s modulus, and elongation at break increased by 208.6, 602.6, 208.5, and 292.0%, respectively at 20% processing moisture content. The incorporation of PCL reduced the degree of starch gelatinization by interfering with moisture migration during compression molding due to its (PCL) hydrophobicity. At both processing moisture levels of 9.3 and 20%, PCL incorporation had significant impacts on the tensile properties of the plasticized pea starch. Flax fiber incorporation also increased the tensile strength, yield strength, and Young’s modulus while concomitantly reducing the elongation at break of the plasticized pea starch. In the TPS/PCL/flax fiber ternary composites, both PCL and flax fiber improved the tensile strength by acting as independent reinforcing materials as no PCL-fiber interfacial bonding was observed. Maximum tensile strength of 11.55 MPa was reached at 10% flax fiber and 40% PCL reinforcement. While the PCL-TPS interfacial interaction was poor, some degree of TPS-flax fiber interfacial bonding was noticed due to their chemical similarity. TPS prepared at 20% moisture showed more moisture affinity than that prepared at 9.3% moisture. The moisture absorption of TPS dropped progressively with the addition of hydrophobic PCL. Fiber incorporation also reduced moisture absorption by the plasticized pea starch. PCL-fiber incorporation also yielded improved moisture resistance vis-à-vis pure TPS. Finally, the TPS processed at 9.3% moisture exhibited higher thermal stability than that processed at 20%. Individual components of the composites retained their respective thermal properties, thus, implying thermodynamic immiscibility
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