Mechanical,Water Absorption and Enzymatic Degradation Properties of Sago Starch Filled Linear Low Density Polyethylene

Abstract

Sago starch filled linear low density polyethylene (LLDPE) composites, have been prepared by melt mixing of the granular starch and LLDPE in a HAAKE internal mixer. The tensile, water absorption and enzymatic degradation properties of the composites have been determined. Incorporation of sago starch into LLDPE led to decrease in tensile strength and elongation at break of the composites. Up to 15 wt.% of sago starch could be added to LLDPE without adverse effects on the tensile properties. The water uptake increased with immersion time and the rate of absorption is strongly controlled by the immersion temperatures. Dramatic reduction in tensile properties were observed in the composites that were immersed in water at 90[ddot]C. The recovery of the tensile strength and elongation at break upon redrying is about 37.5 and 1.6% respectively. The permanent damage to the composites was attributed to severe hydrolysis of the starch particles. The enzymatic degradation study using oc-amylase revealed that both tensile strength and elongation at break reduced with time of treatment. Mode of failures of both LLDPE matrix and its sago starch filled composites, assessed by fracto-graphic analysis in a scanning electron microscope (SEM) are discussed.     

Characterization of extruded film based on thermoplastic potato flour

Potato flour is abundant and less expensive than starch, though its major component is starch. It would therefore seem to be an attractive and viable source of biomass for biodegradable thermoplastic products. This study prepared thermoplastic potato flour (TPF) and thermoplastic potato starch (TPS) films by extrusion and investigated their properties. A mixture of glycerol and triethyl citrate (25−35% of total weight) was chosen for the plasticizer. Properties of the TPF film, such as mechanical properties, surface hydrophilicity, surface energy, moisture sorption isotherm, and glass transition temperature (T_g), were characterized and compared with TPS film. The results showed that TPF film was comparable to TPS film in many properties. The mechanical properties of the TPF film, including tensile strength, elongation at break, and tensile modulus, were similar in magnitude to TPS film. In addition, TPF film showed lower T_g and surface hydrophilicity, but higher surface wetting capacity than TPS film. Components other than starch in potato flour were believed to have had a plasticization effect on TPF properties. Overall, potato flour demonstrated a comparable capacity for manufacturing thermoplastic film similar to the more expensive starch feedstock. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Compatibility of cassava starch films as nitric oxide carrier for potential medical device

Films prepared with bioabsorbable materials (cassava starch, glycerol, and carboxymethyl cellulose (CMC)) can be used as an external support in the myocardial revascularization surgery, releasing nitric oxide (NO) during the tissue regeneration. In the present study, these materials submitted to in vitro degradation tests under physiological conditions, presented the reduction of 38% of weight loss by the modification of native starch using sodium trimetaphosphate (STMP) (15 g/100g of starch). The CMC addition of 10 g/100g of cassava starch increased 119% of the tensile strength of the films in comparison with films prepared without CMC. It was verified that the ruthenium complex trans‐[Ru(NH₃)₄(isn)(NO)](BF₄)₃ incorporated in the starch based films behave similarly as in aqueous solution, releasing NO by photochemical reaction. Macrophage cells were detected in in vivo degradation tests in rats around the implant after 1 and 7 days, and complete biodegradation was observed after 30 days. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41382.     

Environmentally Degradable Blends of Low Density Polyethylene (LDPE) and Partially Carboxymethylated Starch (PCMS)

Abstract

Sodium - salt of partially carboxymethylated starch (Na-PCMS) with degree of substitution (DS) 0.21 and 0.58 was synthesized by etherification of starch. These starch ethers and low density polyethylene (LDPE) were mixed with and without poly(vinylacetate) (PVAc) in various proportions using Brabender mixer. FTIR confirmed the etherification reaction of starch and blending. Positive changes in the mechanical properties as a function of blending, and environmental degradation have been observed. Addition of 5 wt% PVAc improves the blend quality. Samples were exposed to direct sunlight for one month and environmental degradation was measured in terms of change in tensile strength and per cent elongation.     

Effect of pro‐oxidants on biodegradation of polyethylene (LDPE) by indigenous fungal isolate,Aspergillus oryzae

Proxidant additives represent a promising solution to the problem of the environment contamination with polyethylene film litter. Pro‐oxidants accelerate photo‐ and thermo‐oxidation and consequent polymer chain cleavage rendering the product apparently more susceptible to biodegradation. In the present study, fungal strain, Aspergillus oryzae isolated from HDPE film (buried in soil for 3 months) utilized abiotically treated polyethylene (LDPE) as a sole carbon source and degraded it. Treatment with pro‐oxidant, manganese stearate followed by UV irradiation and incubation with A. oryzae resulted in maximum decrease in percentage of elongation and tensile strength by 62 and 51%, respectively, compared with other pro‐oxidant treated LDPE films which showed 45% (titanium stearate), 40% (iron stearate), and 39% (cobalt stearate) decrease in tensile strength. Fourier transform infrared (FTIR) analysis of proxidant treated LDPE films revealed generation of more number of carbonyl and carboxylic groups (1630–1840 cm⁻¹ and 1220–1340 cm⁻¹) compared with UV treated film. When these films were incubated with A. oryzae for 3 months complete degradation of carbonyl and carboxylic groups was achieved. Scanning electron microscopy of untreated and treated LDPE films also revealed that polymer has undergone degradation after abiotic and biotic treatments. This concludes proxidant treatment before UV irradiation accelerated photo‐oxidation of LDPE, caused functional groups to be generated in the polyethylene film and this resulted in biodegradation due to the consumption of carbonyl and carboxylic groups by A. oryzae which was evident by reduction in carbonyl peaks. Among the pro‐oxidants, manganese stearate treatment caused maximum degradation of polyethylene. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polyethylene / amphiprotic blends as alternative for decreasing plastics residues in the environment

This work evaluated the biodegradation of polyethylene and amphiprotic starch blends in the presence of the fungi Phanerochaete chrysosporium (Ph) and Talaromyces wortmannii (BM-10). The mechanical properties of the blends decreased in function from the time of exposure to these fungi. The reduction of the mechanical strength was caused by the consumption of the starch constituent of the polymeric matrix, favoring the growth of the fungi. The production of CO₂ by the fungi, reinforces the theory that the starch was consumed as a source of carbon yielding carbon dioxide and other by-products. Hence, the consumption of starch by these fungi is responsible for the partial degradation of the blends.     

Preparation of nano-Ag-Bi2WO6–TiO2/starch bionanocomposite membranes and mechanism of enhancing visible light degradation of ethylene

Ag–Bi₂WO₆–TiO₂ (ABT) ternary composite photocatalyst was prepared using solvothermal and surface deposition method. Then, the nano photocatalyst was doped into the starch film liquid through internal loading method, and finally, ABT/starch composite film was constructed using tape casting method for visible light catalytic degradation of ethylene. Characterize and analyze the structure and physical properties of nano ABT/starch composite membranes prepared with different ABT loading amounts, and optimize the reaction conditions (ABT addition amount, light intensity, initial concentration of ethylene) on the visible light catalytic degradation performance for ethylene of the composite membrane. The results show that the nano ABT particles and starch molecules have good biocompatibility, and they can be well fused to form a film, without changing the crystal structure of ABT and generating other chemical bond. The results of photocatalytic degradation of ethylene showed that when the loading amount of ABT was 5 wt%, the light intensity was 60.5 mw/cm², and the initial concentration of ethylene was 0.15 mg/L, the ABT/starch film had the best ethylene degradation performance, with a K′ value of 5.6111 × 10⁻⁴ min⁻¹, which is 17.9 times that of the blank starch film. Under the optimal preparation conditions, the thickness, tensile strength, elongation at break of the starch composite film is 168.33 μm, 5.01 Mpa, 32.4%, respectively, and the maximum thermal decomposition temperature is 320.5 °C, which meets the requirements for food packaging materials. After 4 cycles, the catalytic degradation of ethylene by starch composite membrane only decreased by 13.98%, indicating good reusability.     

Compatibilization of starch/poly(butylene adipate‐co‐terephthalate) blown films using itaconic acid and sodium hypophosphite

Itaconic acid (IA) has potential as a compatibilizing agent in polymeric blends due to its unique chemical characteristics. Sodium hypophosphite (SHP) has been studied as a catalyst in esterifying reactions using multicarboxylic acids. Starch/poly(butylene adipate‐co‐terephthalate) blown films containing IA, with and without SHP, were produced. The film containing IA presented higher tensile strength (8.166 MPa) and elongation (891.473%) than the control film (5.548 MPa and 487.637%, respectively). When SHP was added (sample IA‐SHP), tensile strength increased even more (9.215 MPa); however, elongation (636.821%) was lower than in the IA film. This behavior was attributed to crosslinking between two starch itaconoate molecules intermediated by SHP. The increase in the compatibility between the polymeric phases justified the lower permeability to water vapor of the IA‐SHP films and was responsible for the production of films with a more compact and homogeneous structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46629.     

Incorporation of wheat starch and coupling agents into poly(lactic acid) to develop biodegradable composite

Abstract

Composites of poly (lactic acid) (PLA)/wheat starch and PLA/wheat starch/methyldiphenyldiisocyanate, were prepared and characterised in this study. The effects of incorporating different coupling agents on the physical properties and morphology of the composites were studied. Extrusion technology and injection moulding techniques were used to prepare standard tensile and impact test pieces. Tensometry was used to investigate the tensile properties of the composites and impact testing using falling weight technique was used to investigate impact strength. To investigate the thermal behaviour of the composites, differential scanning calorimetry was employed. Water absorption properties of the composites were also investigated. Scanning electron microscopy was used to investigate the morphology of the composites. Starch can be incorporated in a PLA matrix at 10% level without difficulty in processing by extrusion followed by injection moulding to make shaped mouldings in the presence of MDI. With 10% wheat starch and 2% MDI, blends of wheat starch/PLA can reach the tensile strength, elongation, impact strength properties of raw PLA. In the presence of 2% MDI and 10% glycerol, blends of PLA and starch make an entirely flexible material.     

碳酸钙和淀粉对聚乙烯薄膜降解性能影响研究

目的:研究淀粉和CaCO3对塑料薄膜的降解影响。方法:将CaCO3填充膜和淀粉填充膜经自然曝露、紫外线照射和土埋处理,测试拉伸强度、断裂伸长率和分子量的变化。结果:自然曝露30d,CaCO3填充膜和淀粉填充薄膜的平均拉伸强度分别下降80.8%和54.4%,平均断裂伸长率分别下降99.4%和98.3%,分子量分别下降25.3%和13.8%;紫外光照120h,CaCO3填充薄膜和淀粉填充薄膜的平均拉伸强度分别下降14.7%和45.9%,断裂伸长率分别下降97.3%和97.0%,分子量分别下降66.7%和48.3%;土埋203d,CaCO3填充薄膜和淀粉填充薄膜的失重率分别为2.2%和15.0%。结论:CaCO3和淀粉均能加速聚乙烯塑料薄膜的降解,其中CaCO3的光降解性能方面优于淀粉,而淀粉的生物降解性能优于CaCO3。     

Dispersion of multiwalled carbon nanotubes in polyacrylonitrile‐co‐starch copolymer matrix for enhancement of electrical,thermal, and gas barrier properties

Nanomaterials gained great importance on account of their wide range of applications in many areas. Carbon nanotubes (CNTs) exhibit exceptional electrical, thermal, gas barrier, and tensile properties and can therefore be used for the development of a new generation of composite materials. Functionalized multiwalled carbon nanotubes (MWCNTs) reinforced Polyacrylonitrile‐co‐starch nanocomposites were prepared by in situ polymerization technique. The structural property of PAN‐co‐starch/MWCNT nanocomposites was studied by X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. The conductivity, tensile strength, and thermal properties of nanocomposites were measured as a function of MWCNT concentrations. The thermal stability, conductivity, and tensile strength of PAN‐co‐starch/MWCNT nanocomposites were improved with increasing concentration of MWCNTs. Oxygen barrier property of PAN‐co‐starch/MWCNT nanocomposites was calculated and it was found that, the property was reduced substantially with increase of MWCNTs proportion. The synthesized PAN‐co‐starch/MWCNT nanocomposites may used for electrostatically dissipative materials, aerospace or sporting goods, and electronic materials. © 2013 Society of Plastics Engineers     

Structure‐property relationship in polyurethane elastomers containing starch as a crosslinker

Polyurethane elastomers were synthesized using polypropylene glycol (PPG 2000) as the polyol and starch as the multifunctional crosslinker in varying concentrations. Thermal and mechanical properties were measured by DSC, DMA and tensile tests. The morphology was examined by SEM. The swelling behavior of the polyurethanes in various solvents was investigated and the solubility parameter was determined. All these properties were compared with those of polyurethanes containing 1,1,1 ‐trimethylol propane (TMP) as the crosslinker. Starch‐based polyurethanes exhibited better mechanical properties. The effect of varying the starch:TMP ratio on the mechanical strength was also studied. With increasing starch content, the tensile strength and elongation increased. The starch‐based PUs exhibited two glass transitions, whereas TMP‐based PUs exhibited one T_g. No significant difference in the T_gs of the two PUs was observed. The activation energy of St‐PU calculated from DMA was 69 kcal/mol. Soil degradation tests indicated greater biodegradability in polyurethanes containing starch than in those containing TMP.     

Biodegradable Composition Based on Low Density Polyethylene

ABSTRACT

Sodium salt of partially carboxymethylated starch (Na-PCMS) with degree of substitution DS 0.58 and starch acetate with DS 1.7 were synthesized from starch. These starch ethers and acetates along with starch, poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA) were blended with low density polyethylene (LDPE) in various proportion using Brabender mixer. Addition of 5% stearic acid as a plasticizer improves the blend compatibility. Change in mechanical properties were monitored and optimum composition of blend were prepared. This blend was studied for growth of Bacillus species (BS) and degradation by means of weight loss and change in mechanical properties viz., tensile strength and % elongation, and total cellular protein. Degradation of pure polymers within one month period was also examined.     

Cold Plasma Modification Effects on the Water Flow through Sintered UHMWPE Membranes

Natural rubber latex and various concentration of natural antioxidant were blended in different ratios and irradiated at various absorbed doses by gamma rays from Co-60 source at room temperature. The aqueous extraction of Diospyros peregrina was used as natural antioxidant. It was found that the addition of different concentration of natural antioxidant into natural rubber latex improve the aging property of the film. Decreasing in tensile strength of rubber film with 10 phr natural antioxidant and 15 kGy radiation dose after 24 hours aging at 100°C was 9.34% compared to 13.89% for film without natural antioxidant. The tensile strength, tear resistance and modulus at 500% elongation of the rubber film were found to be optimum at 15 kGy radiation dose and with 10 phr natural antioxidant. Elongation at break, permanent set and swelling ratio decreases with the increasing absorbed radiation dose as well as the concentration of the natural antioxidant.     

The Effect of Environmental Treatments on Fiber Surface Properties and Tensile Strength of Sugar Palm Fiber-Reinforced Epoxy Composites

Fiber glass has been used widely in manufacturing industries, especially marine industries, because of low cost and high strength. However, glass fiber can cause acute irritation to the skin, eyes, and upper respiratory tract. This study looked at the possibility of substituting glass fiber with natural fiber in composite materials. The surface properties of sugar palm fiber (Arenga pinnata) were modified using seawater and freshwater as treatment substances. This led to biological, chemical, and water degradation of the sugar palm fiber. Morphological and structural changes in the fibers were investigated using a scanning electron microscope (SEM). A series of tensile tests based on ASTM D638-99 was carried out on epoxy composites with 15% sugar palm fiber by volume. It was found that seawater and freshwater treatments improved the surface properties of the sugar palm fiber and thus resulted in better adhesion quality as compared to untreated fiber. An improvement in tensile strength also supported this finding. Treatment with seawater for 30 days proved to be the best, with 67.26% increase in tensile strength.     

苏芸金杆菌/淀粉/聚乙烯共混地膜

以玉米淀粉、线型低密度聚乙烯及能在膜上生长的苏芸金杆菌菌粉共混制得淀粉塑料.通过地埋降解试验研究了淀粉塑料中淀粉的降解率,并测定了其物理性能.结果发现地埋降解120天后5%菌粉和50%淀粉的薄膜淀粉降解率达到89.52%,扫描电镜观察大部分淀粉颗粒破碎,出现许多小孔;不加菌粉的淀粉降解率只有35.48%,表明添加的菌粉对淀粉降解有明显的促进作用.物理性能测试结果表明含淀粉40%～50%的共混薄膜有一定的拉伸强度和透光率,可以用作地膜.     

The Effect of glycerol on the crystalline,thermal, and tensile properties of CaCl2‐doped starch/PVA films

Starch/poly(vinyl alcohol) (PVA) films with the addition of 10 wt% CaCl₂ and various content of glycerol were prepared. The effect of glycerol on the crystalline, thermal, and tensile properties of CaCl₂‐doped starch/PVA films was studied by X‐ray diffraction, thermogravimetric analysis (TGA), and tensile testing, respectively. The effect of glycerol on the miscibility of CaCl₂‐doped starch/PVA films was studied by scanning electron microscopy. The CaCl₂‐doped starch/PVA film became more homogeneous after the addition of glycerol. The addition of glycerol would increase the crystallinity of CaCl₂‐doped starch/PVA film. With the addition of 10 wt% glycerol and 10 wt% CaCl₂, the starch/PVA film showed the highest degree of crystallinity. The TGA results show that the thermal stability of CaCl₂‐doped starch/PVA film increased after the addition of glycerol. The toughness of CaCl₂‐doped starch/PVA films was enhanced with the addition of glycerol. The starch/PVA film with the addition of 10 wt% CaCl₂ and 20 wt% glycerol showed the tensile strength of 17 MPa and the elongation at break of 428%. Moreover, the water sorption of CaCl₂‐doped starch/PVA film decreased after the addition of glycerol at the low and intermediate relative humidity of 33 and 54%. POLYM. COMPOS., 37:3191–3199, 2016. © 2015 Society of Plastics Engineers     

Development and evaluation of a novel pH indicator biodegradable film based on cassava starch

A pH indicator film based on cassava starch plasticized with sucrose and inverted sugar and incorporated with grape and spinach extracts as pH indicator sources (anthocyanin and chlorophyll) has been developed, and its packaging properties have been assessed. A second‐order central composite design (2²) with three central points and four star points was used to evaluate the mechanical properties (tensile strength, tensile strength at break, and elongation at break percentage), moisture barrier, and microstructure of the films, and its potential as a pH indicator packaging. The films were prepared by the casting technique and conditioned under controlled conditions (75% relative humidity and 23°C), at least 4 days before the analyses. The materials were exposed to different pH solutions (0, 2, 7, 10, and 14) and their color parameters (L*, a*, b*, and haze) were measured by transmittance. Grape and spinach extracts have affected the material characterization. Film properties (mechanical properties and moisture barrier) were strongly influenced by extract concentration presenting lower results than for the control. Films containing a higher concentration of grape extract presented a greater color change at different pH's suggesting that anthocyanins are more effective as pH indicators than chlorophyll or the mixture of both extracts. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Human-lymphocyte cell friendly starch–hydroxyapatite biodegradable composites: Hydrophilic mechanism,mechanical, and structural impact

Biodegradable starch (Str) polymer was derived from potato, a plant-based natural carbohydrate polymers source, by one-pot synthesis. Hydroxyapatite (HA) was produced from goat bone by step sintering. The inexpensive starch/HA thin film composites were fabricated by customized spin coating. This study revealed that the hydrogen bond energy and distance have significant effect on glass transition temperature of the polymer. The 40 wt % HA contained starch (StrHA40) composite thin film showed excellent tensile strength (3.03 + −0.03 MPa), elongation (21.5 + −5.5%) and modulus (15.5 + −0.2 MPa) closed to human skin. The in vitro swelling and biodegradation kinetics of pristine starch and pure HA has been controlled and improved by using suitable composition. This study postulated the probable water molecule-adsorption mechanisms of pristine starch and starch/HA composite films. The StrHA40 composite showed excellent biocompatibility to the human-blood derived lymphocyte cells. Therefore, the starch/HA thin film composite-based biodegradable scaffolds developed in the present study can be an excellent potential candidate for soft tissue regeneration and/or replacement applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48913.     

Highly deacetylated chitosan and its properties

A preparative method has been established for obtaining chitosan products which have a desired degree of deacetylation of up to virtually 100%. Effective deacetylation was attained by intermitently washing the intermediate product in water two or more times during the alkali treatment. The weight average molecular weight (M?_w) of the product, which was measured by gel permeation liquid chromatography, was about 5 × 10⁵ at the highest deacetylation of nearly 100%, and the degradation of the molecular chain was not so significant. Tensile strength of the wet film increased markedly with increasing degree of deacetylation, while the dry film did not show a corresponding significant increase of the tensile strength. In the infrared spectra of chitosan film new sharp bands appeared especially at the high degree of deacetylation. This was attributed to increased “crystallization” brought about by high deacetylation.