scholarly journals Rheological, Thermal, and Degradation Properties of PLA/PPG Blends

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3519 ◽  
Author(s):  
Dong Xie ◽  
Yang Zhao ◽  
Yuan Li ◽  
Anna Marie LaChance ◽  
Jinqing Lai ◽  
...  
Keyword(s):  
Melt Processing ◽  
Polypropylene Glycol ◽  
Melt Viscosity ◽  
Pseudoplastic Fluid ◽  
Capillary Rheometry ◽  
Torque Rheometry ◽  
Fluid Behavior ◽  
Degradation Degree ◽  
Degradation Properties ◽  
The Relationship

The work presented herein focuses on simulating the compounding process via a torque rheometer, as well as the relationship between the melt viscosity and the polymer molecular weight (MW). We aim to predict the plasticization of polylactic acid (PLA) using polypropylene glycol (PPG) with different MWs. The rheological properties of the PLA/PPG composites containing PPG with different MWs were systematically studied by capillary rheometry and torque rheometry. The initial degradation of PLA/PPG composites during melt processing was monitored in real time. The results indicate that PPG can significantly reduce the melt viscosity of PLA/PPG composites, leading to obvious pseudoplastic fluid behavior. The lower the MW of PPG, the lower the viscosity of the PLA/PPG composite. The addition of PPG was favorable for the degradation of PLA during processing, and the degradation degree of the composite materials increased as the MW of PPG was decreased.

scholarly journals Evaluation of the Relationship among Biogenic Amines, Nitrite and Microbial Diversity in Fermented Mustard

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6173
Author(s):  
Yangyang Yu ◽  
Lu Li ◽  
Yujuan Xu ◽  
Kejing An ◽  
Qiao Shi ◽  
...  
Keyword(s):  
Biogenic Amines ◽  
High Throughput Sequencing ◽  
Starter Cultures ◽  
Sequencing Analysis ◽  
Maximum Residue Limit ◽  
Safety Standard ◽  
Bacteria And Fungi ◽  
High Level ◽  
Degradation Properties ◽  
The Relationship

Biogenic amines (BAs) and nitrites are both considered harmful compounds for customer health, and are closely correlated with the microorganisms in fermented mustard (FM). In this study, BAs and nitrite contents in fifteen FM samples from different brands were analyzed. The concentrations of cadaverine in one sample and of histamine in one sample were above the toxic level. Moreover, five FM samples contained a high level of nitrite, exceeding the maximum residue limit (20 mg/kg) suggested by the National Food Safety Standard. Then, this study investigated bacterial and fungal communities by high-throughput sequencing analysis. Firmicutes and Basidiomycota were identified as the major bacteria and fungi phylum, respectively. The correlations among microorganisms, BAs and nitrite were analyzed. Typtamine showed a positive correlation with Lactobacillus and Pseudomonas. Cadaverine and nitrite is positively correlated with Leuconostoc. Furthermore, thirteen strains were selected from the samples to evaluate the accumulation and degradation properties of their BAs and nitrite. The results indicated that the Lactobacillus isolates, including L. plantarum GZ-2 and L. brevis SC-2, can significantly reduce BAs and nitrite in FM model experiments. This study not only assessed the contents of BAs and nitrite in FM samples, but also provided potential starter cultures for BAs and nitrite control in the FM products industry.

scholarly journals Effect of Limestone Powder on Thaumasite Form of Sulfate Attack (TSA) of Cement-Based Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yuxin Gao ◽  
Yaoling Luo ◽  
Lili Jia ◽  
Wen Yang ◽  
Chong Wang
Keyword(s):  
New Product ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
Test Results ◽  
X Ray Diffraction ◽  
Cement Based Materials ◽  
Powder Content ◽  
Degradation Degree ◽  
The Relationship ◽  
Hydrated Calcium

Limestone powder can cause the thaumasite form of sulfate attack (TSA) of cement-based materials, but the relationship between the content of limestone powder and the degree of TSA is unclear. Hence, six different contents of limestone powder (0%, 5%, 10%, 15%, 30%, and 45%) were used to study the effect of the limestone powder content on the TSA of cement-based materials according to appearance and Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), and chemical analyses. The test results indicated that limestone powder could promote sulfate attack. The formation of ettringite and gypsum was accelerated when the content of the limestone powder was not more than 10%. The degradation degree of the TSA was the most severe when the content of limestone powder was 30%. A new product, hydrated calcium carboaluminate, was found when the content of the limestone powder was 45%, and the degradation of the TSA was also delayed.

Sorption Behavior of Radionuclides on Calcium-Leached Mortar

2000 ◽  
Vol 663 ◽  
Author(s):  
Nobuo Ashikawa ◽  
Takatoshi Tajima ◽  
Hiroshi Saito ◽  
Ai Fujiwara
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Electrical Potential ◽  
Potential Gradient ◽  
Extended Period ◽  
Distribution Coefficients ◽  
Sorption Behavior ◽  
Degradation Degree ◽  
The Relationship ◽  
Low Level Radioactive Waste

ABSTRACTLow-level radioactive waste (LLRW) is disposed of by shallow land burial. Reinforced concrete is used as the radioactive waste repository. However, the concrete structure is in contact with water and will gradually degrade over an extended period of time due to leaching.It is important to investigate the interaction between radionuclides and degraded concrete in the safety assessment of nuclear waste disposal. The authors measured the distribution coefficients (Kd) of various radionuclides for calcium-leached mortars. The calcium-leached mortars were prepared by an accelerated leaching test for mortar based on the electrical potential gradient. These degraded conditions are similar to that of degraded concrete in contact with water for a long period of time. The degradation degree of calcium-leached mortar is evaluated by the CaO/SiO2 molarratio (Ca/Si ratio) of calcium silicate hydrate (C-S-H).As a result, the relationship between Kd and the Ca/Si ratio in C-S-H can be roughly grouped into the following three types:1.137Cs and 85Sr – Kd decreases with an increase in the Ca/Si ratio.2. 95mTc and 110mAg – There is no correlation between Kd and the Ca/Si ratio.3. 14C, 241Am and 125I – Kd increases with an increase in the Ca/Si ratio.

scholarly journals Synthesis of Linseed Oil-Based Waterborne Urethane Oil Wood Coatings

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1235 ◽  
Author(s):  
Chia-Wei Chang ◽  
Jing-Ping Chang ◽  
Kun-Tsung Lu
Keyword(s):  
Linseed Oil ◽  
Average Molecular Weight ◽  
Solid Content ◽  
Hexamethylene Diisocyanate ◽  
Molar Ratio ◽  
Pseudoplastic Fluid ◽  
Weakly Alkaline ◽  
Molar Ratios ◽  
Fluid Behavior ◽  
Wood Coatings

The linseed oil glyceride (LOG) was synthesized by using a transesterification process with a glycerol/linseed oil molar ratio of 1.0. The waterborne urethane oil (WUO) wood coating was prepared by acetone process. First, dimethylolpropionic acid was reacted with hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI), followed by adding LOG at various NCO/OH molars of 0.7, 0.8, and 0.9, respectively, and the COOH-containing prepolymer was obtained. Then, the ionomer which was prepared by neutralizing prepolymer with trimethylamine, was dispersed by adding deionized water, and the water–acetone dispersion was obtained. Finally, the acetone was removed by vacuum distillation. In the whole synthesized process, the LOG and COOH-containing prepolymer could be steadily synthesized by FTIR analysis, and the weight-average molecular weight and polydispersity of COOH-containing prepolymer increased with an increase of NCO/OH molar ratios. During the water dispersion process of the ionomer acetone solution, the point of phase inversion was prolonged, meaning the solid content decreased with an increase of NCO/OH molar ratios. After acetone was removed, the color of WUO was milky-white, and it was weakly alkaline and possessed a pseudoplastic fluid behavior. The particle size of WUO increased with increasing of NCO/OH molar ratios, however, the storage stability was extended for HDI and shortened for IPDI synthesized with increasing of NCO/OH molar ratios.

Two novel porous MOFs with square-shaped cavities for the removal of toxic dyes: adsorption or degradation?

2017 ◽  
Vol 41 (24) ◽  
pp. 15204-15209 ◽  
Author(s):  
Huijun Li ◽  
Qingqing Li ◽  
Yaling He ◽  
Zhouqing Xu ◽  
Qingjie Tang
Keyword(s):  
Toxic Dyes ◽  
Dyes Adsorption ◽  
Degradation Properties ◽  
The Relationship

Two new networks with different-sized pores were constructed. Their adsorption and degradation properties were studied in detail to clarify the relationship between adsorption and degradation.

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