scholarly journals Effects of Citric Acid on Structures and Properties of Thermoplastic Hydroxypropyl Amylomaize Starch Films

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1565 ◽  
Author(s):  
Yang Qin ◽  
Wentao Wang ◽  
Hui Zhang ◽  
Yangyong Dai ◽  
Hanxue Hou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Citric Acid ◽  
Average Molecular Weight ◽  
Reactive Extrusion ◽  
Cross Linking ◽  
Hot Press ◽  
Structures And Properties ◽  
Initial Ph ◽  
Starch Films ◽  
Hydrolysis Of

Hydroxypropyl amylomaize starch (HPAS) films were prepared by hot press. The effects of initial pH of HPAS on the mechanical properties, molecular interaction, structure, and cross-linking degree of the resultant films were investigated. A weak acidic condition was suitable for cross-linking of citric acid and HPAS by reactive extrusion. The film of HPAS with an initial pH of 5.66 had the maximum tensile strength of 7.20 MPa and elongation-at-break of 94.53%, and the weight average molecular weight of HPAS increased to 4.17 × 105 g/mol. An appropriate initial pH facilitated the formation of diester bonds between HPAS and citric acid during extrusion, but too low initial pH levels resulted in hydrolysis of starch molecules and reduced the mechanical properties.

scholarly journals ACID CITRIC CROSS –LINKING OF STARCH/ POLY(VINYL ALCOHOL) BLEND

2011 ◽  
Vol 14 (4) ◽  
pp. 57-66
Author(s):  
Nguyen Thao Tran ◽  
Diem Thi Tuyet Nguyen ◽  
Tai Tan Dang
Keyword(s):  
Mechanical Properties ◽  
Citric Acid ◽  
Water Absorption ◽  
Vinyl Alcohol ◽  
Hydrophilic Polymers ◽  
Poly Vinyl Alcohol ◽  
Cross Linking ◽  
Biodegradable Materials ◽  
Starch Films

In recent times, a number of studies worldwide have focused on strengthening the interaction between the TPS and PVA or modifying with several agents to achieve better mechanical properties, in order to apply in the manufacturing of biodegradable materials. In addition, since both starch and PVA are hydrophilic polymers, they have very strong water absorption ability. In this research, the possibility of cross-linking starch films using citric acid to improve their strength and stability was examined. The study also showed the prospect to limit water absorption of the blend when solubility of the mixture can be reduced to 40%.

Influence of Citric Acid and Curing Time on Water Uptake

2014 ◽  
Vol 625 ◽  
pp. 123-126 ◽  
Author(s):  
Sohibatul Muizzah Mohamad Izhar ◽  
Ku Zilati Ku Shaari ◽  
Zakaria Man ◽  
Yon Norasyikin Samsudin
Keyword(s):  
Citric Acid ◽  
Water Uptake ◽  
Barrier Properties ◽  
High Water ◽  
Cross Linking ◽  
Curing Time ◽  
Gas Barrier ◽  
Water Sensitivity ◽  
Hydrophilic Character ◽  
Starch Films

Starch is highly promising biopolymer for the production of packaging material since it gives films a good tensile and gas barrier properties. However, non-plasticized starch films are brittle and their hydrophilic character results in poor moisture barrier properties and high water sensitivity. In order to improve films formation and material properties of starch, plasticization and chemical modification such as cross-linking of the starch is required. The cross-linking reaction able to improve thermal stability, tensile strength and decreased the dissolution of starch films in water and formic acid. From the study, the percentage of water uptake reduced when the blending ratio of citric acid increased.The percentage of water uptake highly affected by curing time compared to blending ratio. Increasing the curing time from 1 hour to 2 hour significantly reduced the percentage of water uptake. At 4 hour curing time, the percentage water uptake reached equilibrium faster than 3 hour curing time. This shows that more citric acid molecules were chemically bonded with the starch chains, resulting in higher cross link degree and thus, reduced the percentage of water uptake.

scholarly journals Analysis of the Effect of Processing Conditions on Physical Properties of Thermally Set Cellulose Hydrogels

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1066 ◽  
Author(s):  
Tim Huber ◽  
Sean Feast ◽  
Simone Dimartino ◽  
Wanwen Cen ◽  
Conan Fee
Keyword(s):  
Mechanical Properties ◽  
Network Formation ◽  
Aqueous Sodium Hydroxide ◽  
Cross Linking ◽  
Processing Conditions ◽  
Hot Press ◽  
Thermal Gelation ◽  
Complex Shapes ◽  
Bond Network ◽  
Chemical Cross Linking

Cellulose-based hydrogels were prepared by dissolving cellulose in aqueous sodium hydroxide (NaOH)/urea solutions and casting it into complex shapes by the use of sacrificial templates followed by thermal gelation of the solution. Both the gelling temperatures used (40–80 °C), as well as the method of heating by either induction in the form of a water bath and hot press or radiation by microwaves could be shown to have a significant effect on the compressive strength and modulus of the prepared hydrogels. Lower gelling temperatures and shorter heating times were found to result in stronger and stiffer gels. Both the effect of physical cross-linking via the introduction of additional non-dissolving cellulosic material, as well as chemical cross-linking by the introduction of epichlorohydrin (ECH), and a combination of both applied during the gelation process could be shown to affect both the mechanical properties and microstructure of the hydrogels. The added cellulose acts as a physical-cross-linking agent strengthening the hydrogen-bond network as well as a reinforcing phase improving the mechanical properties. However, chemical cross-linking of an unreinforced gel leads to unfavourable bonding and cellulose network formation, resulting in drastically increased pore sizes and reduced mechanical properties. In both cases, chemical cross-linking leads to larger internal pores.

The Properties and Hydrolysis of Polysiloxanes with Cyanoethyl Groups

2011 ◽  
Vol 306-307 ◽  
pp. 1663-1666
Author(s):  
Rui Fang Guan ◽  
Yu Rong Dong
Keyword(s):  
Mechanical Properties ◽  
Average Molecular Weight ◽  
Dynamic Mechanical Properties ◽  
Carboxyl Groups ◽  
Number Average Molecular Weight ◽  
Reaction Conditions ◽  
Factors Influencing ◽  
Hydrolysis Of ◽  
Optimal Reaction ◽  
Thermal Stability Of

Polysiloxanes with cyanoethyl groups (PDMS-CN) is a useful functional polysiloxanes. In this paper, the polysiloxane with various number average molecular weight (Mn) and cyanoethyl groups were prepared. Mns of PDMS-CN were determined by GPC. The contents of cyanoethyl groups were determined by 1H NMR. The dynamic mechanical properties and thermal stability of PDMS-CN were investigated by DSC and TGA respectively. The hydrolysis of PDMS-CNs give the polysiloxanes with carboxyl groups. The factors influencing the hydrolysis of cyanoethyl groups were discussed by orthogonal array and the optimal reaction conditions were confirmed. This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text

Preparation of Cross-Linked High Amylose Corn-Starch and Its Effects on Self-Reinforced Starch Films

2016 ◽  
Vol 12 (7) ◽  
pp. 673-680 ◽  
Author(s):  
Xingxun Liu ◽  
Cao Lan ◽  
Amjad Al ◽  
Long Yu ◽  
Sumei Zhou
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Tensile Testing ◽  
Corn Starch ◽  
Cross Linking ◽  
Gelatinization Temperature ◽  
Starch Films ◽  
The Cross ◽  
High Amylose ◽  
Positive Effect

Abstract Incorporation of biodegradable self-reinforced starch composite to starch film is a promising method to improve the mechanical property of the film. In this study, cross-linked starch with different degree of cross-linking level was used as matrix to reinforce in the starch film. The thermal properties and mechanical properties of the cross-linked starch were investigated by differential scanning calorimetory (DSC), thermogravimetric analysis (TGA) and Instron tensile testing respectively. It was found that the cross-linking level greatly impact on the thermal properties of the cross-linked starch. The gelatinization temperature of starch increased with the increasing level of cross-linking modification. In addition, the cross-linking modification showed a positive effect on the mechanical properties of the starch films when the cross-linking level was controlled at a certain range.

scholarly journals Characteristic of Bamboo Particleboard Bonded with Citric Acid

2017 ◽  
Vol 4 (1) ◽  
pp. 31-35
Author(s):  
Ragil Widyorini ◽  
Ari Puspa Yudha ◽  
Yuditya Adifandi ◽  
Kenji Umemura ◽  
Shuichi Kawai
Keyword(s):  
Mechanical Properties ◽  
Citric Acid ◽  
High Performance ◽  
Raw Materials ◽  
Value Added ◽  
Physical And Mechanical Properties ◽  
Hot Press ◽  
Biomass Waste ◽  
Japanese Industrial Standard ◽  
Citric Acid Content

Converting biomass waste to high value-added product, such as biocomposite, tends to attract the interest of researcher and industry. Reducing the utilization of synthetic resin adhesives becomes one of the important points, considering the safe global environment. Binderlessboard is a product whose bonding depends mainly on the chemical composition of the raw materials. The aim of this research was to develop bio-based composites made from bamboo biomass waste materials. This report focused on the physical and mechanical properties of the particleboards. To improve the properties of the boards, the possibility of using citric acid was investigated and discussed. Petung bamboo particles (Dendrocalamus asper Backer) were used in this research. The contents of citric acid were ranged in 0% (binderlessboard), 10%, and 20% based on dried particles. The dimension of the boards was 25 x 25 x 0.7 cm, with the target density was 0.9 g/cm3. The particleboards were hot pressed at 200ºC and 220ºC for 10 and 15 min. The physical and mechanical properties of those particleboards were then evaluated based on Japanese Industrial Standard A 5908 for particleboard. The results showed that the physical and mechanical properties of the boards improved significantly by adding the citric acid. The bamboo particleboards obtained had good properties, with the spesific IB, specific MOR and specific MOE values under the optimum condition of 20 wt % citric acid content and 200ºC hot press were 0.44 MPa, 15.1 MPa and 4.6 GPa, respectively. It stated that bamboo particleboards bonded using citric acid had high performance on mechanical properties and good dimensional stability.

scholarly journals Citric acid cross-linking of starch films

2010 ◽  
Vol 118 (3) ◽  
pp. 702-711 ◽  
Author(s):  
Narendra Reddy ◽  
Yiqi Yang
Keyword(s):  
Citric Acid ◽  
Cross Linking ◽  
Starch Films

scholarly journals Improving Rheological and Mechanical Properties of Various Virgin and Recycled Polypropylenes by Blending with Long-Chain Branched Polypropylene

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1137
Author(s):  
Sascha Stanic ◽  
Thomas Koch ◽  
Klaus Schmid ◽  
Simone Knaus ◽  
Vasiliki-Maria Archodoulaki
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Test ◽  
Reactive Extrusion ◽  
Original Material ◽  
Melt Flow Rate ◽  
Single Screw Extruder ◽  
Pp Blends ◽  
The Impact ◽  
Long Chain

Blends of two long-chain branched polypropylenes (LCB-PP) and five linear polypropylenes (L-PP) were prepared in a single screw extruder at 240 °C. The two LCB-PPs were self-created via reactive extrusion at 180 °C by using dimyristyl peroxydicarbonate (PODIC C126) and dilauroyl peroxide (LP) as peroxides. For blending two virgin and three recycled PPs like coffee caps, yoghurt cups and buckets with different melt flow rate (MFR) values were used. The influence of using blends was assessed by investigating the rheological (dynamic and extensional rheology) and mechanical properties (tensile test and impact tensile test). The dynamic rheology indicated that the molecular weight as well as the molecular weight distribution could be increased or broadened. Also the melt strength behavior could be improved by using the two peroxide modified LCB-PP blends on the basis of PODIC C126 or PEROXAN LP (dilauroyl peroxide). In addition, the mechanical properties were consistently enhanced or at least kept constant compared to the original material. In particular, the impact tensile strength but also the elongation at break could be increased considerably. This study showed that the blending of LCB-PP can increase the investigated properties and represents a promising option, especially when using recycled PP, which demonstrates a real “up-cycling” process.

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