A comparison of induction time and crystallization rate for syndiotactic polystyrene

2002 ◽  
Vol 42 (4) ◽  
pp. 694-706 ◽  
Author(s):  
Richard D. Sudduth ◽  
Pavan Kyarala ◽  
Qin Sheng
Keyword(s):  
Induction Time ◽  
Crystallization Rate ◽  
Syndiotactic Polystyrene

scholarly journals Role of different lignin systems in polymers: mechanical properties and thermal stability

2020 ◽  
Vol 22 (4) ◽  
pp. 10-16
Author(s):  
Gvlmira Hasan ◽  
Dilhumar Musajan ◽  
Gong-bo Hou ◽  
Mingyu He ◽  
Ying Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Induction Time ◽  
Crystallization Rate ◽  
Scanning Calorimetry ◽  
Oxidation Induction Time ◽  
Thermal Stability Of

AbstractLignin was used to study the mechanical properties and thermal stability of polymers. The lignin was blended with three kinds of polymers, and the addition of lignin was 0.5 wt%. Under the condition of thermal oxidation, the thermal stability of lignin/polymer samples varies with the structure of lignin. The effects of lignin on the mechanical properties and thermal stability of the polymers were investigated by oxidation induction time (OIT), rheological properties, mechanical properties and differential scanning calorimetry (DSC). The results show that the effect of lignin on the thermal properties of polymer samples is 2~3°C. It can be inferred that lignin can effectively improve the interaction between polymer molecular chain segments, and improve the crystallization rate and rigidity to a certain extent, so it can be seen that lignin has good compatibility and thermal stability.

scholarly journals Chemical and Physical Properties of Some Hazelnut Varieties Grown in Portugal

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1476
Author(s):  
Ana Cristina Ferrão ◽  
Raquel P. F. Guiné ◽  
Elsa Ramalhosa ◽  
Arminda Lopes ◽  
Cláudia Rodrigues ◽  
...  
Keyword(s):  
Discriminant Analysis ◽  
Physical Properties ◽  
Water Activity ◽  
Induction Time ◽  
Oxidation Stability ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Nutritional Characteristics ◽  
Physical And Chemical ◽  
And Chemical Properties

Hazelnuts are one of the most appreciated nuts worldwide due to their unique organoleptic and nutritional characteristics. The present work intended to analyse several physical and chemical properties of different hazelnut varieties grown in Portugal, namely Tonda de Giffoni, Grada de Viseu, Segorbe, Longa de Espanha, Butler, Gunslebert, and Negreta. In general, the results revealed statistically significant differences between the varieties under study. The Gunslebert had more elongated hazelnuts and with heavier shelled fruits, while the kernels of the Grada de Viseu revealed to be heavier. Grada de Viseu was harder in the shell, Gunslebert had a harder core, and Segorbe was more resistant to fracture. Fat was the more representative component for all varieties and in some cases the values of moisture and water activity were over the recommended amount (≥0.62). Tonda de Giffoni was the variety with the highest induction time, indicating the highest oxidation stability. Moreover, discriminant analysis revealed that the variables more important to distinguish the varieties were protein (λ = 0.007) and water activity (λ = 0.010). The results of this study help to better understand the differences between some hazelnut varieties that are cultivated in Portugal, which gives important hints for all players in the hazelnut sector.

scholarly journals A Review: Research Progress in Modification of Poly (Lactic Acid) by Lignin and Cellulose

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 776
Author(s):  
Sixiang Zhai ◽  
Qingying Liu ◽  
Yuelong Zhao ◽  
Hui Sun ◽  
Biao Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Composite Materials ◽  
Crystallization Rate ◽  
Research Progress ◽  
Poly Lactic Acid ◽  
Green Composite ◽  
Materials Development ◽  
Research Attention ◽  
Biomass Components

With the depletion of petroleum energy, the possibility of prices of petroleum-based materials increasing, and increased environmental awareness, biodegradable materials as a kind of green alternative have attracted more and more research attention. In this context, poly (lactic acid) has shown a unique combination of properties such as nontoxicity, biodegradability, biocompatibility, and good workability. However, examples of its known drawbacks include poor tensile strength, low elongation at break, poor thermal properties, and low crystallization rate. Lignocellulosic materials such as lignin and cellulose have excellent biodegradability and mechanical properties. Compounding such biomass components with poly (lactic acid) is expected to prepare green composite materials with improved properties of poly (lactic acid). This paper is aimed at summarizing the research progress of modification of poly (lactic acid) with lignin and cellulose made in in recent years, with emphasis on effects of lignin and cellulose on mechanical properties, thermal stability and crystallinity on poly (lactic acid) composite materials. Development of poly (lactic acid) composite materials in this respect is forecasted.

scholarly journals Isothermal Crystallization Kinetics of Poly(ethylene oxide)/Poly(ethylene glycol)-g-silica Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 648
Author(s):  
Xiangning Wen ◽  
Yunlan Su ◽  
Shaofan Li ◽  
Weilong Ju ◽  
Dujin Wang
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Poly Ethylene Glycol ◽  
Isothermal Crystallization Kinetics ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Kinetics Of

In this work, the crystallization kinetics of poly(ethylene oxide) (PEO) matrix included with poly(ethylene glycol) (PEG) grafted silica (PEG-g-SiO2) nanoparticles and bare SiO2 were systematically investigated by differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM) method. PEG-g-SiO2 can significantly increase the crystallinity and crystallization temperature of PEO matrix under the non-isothermal crystallization process. Pronounced effects of PEG-g-SiO2 on the crystalline morphology and crystallization rate of PEO were further characterized by employing spherulitic morphological observation and isothermal crystallization kinetics analysis. In contrast to the bare SiO2, PEG-g-SiO2 can be well dispersed in PEO matrix at low P/N (P: Molecular weight of matrix chains, N: Molecular weight of grafted chains), which is a key factor to enhance the primary nucleation rate. In particular, we found that the addition of PEG-g-SiO2 slows the spherulitic growth fronts compared to the neat PEO. It is speculated that the interfacial structure of the grafted PEG plays a key role in the formation of nuclei sites, thus ultimately determines the crystallization behavior of PEO PNCs and enhances the overall crystallization rate of the PEO nanocomposites.

scholarly journals Manufacturing PLA/PCL Blends by Ultrasonic Molding Technology

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2412
Author(s):  
Inés Ferrer ◽  
Ariadna Manresa ◽  
José Alberto Méndez ◽  
Marc Delgado-Aguilar ◽  
Maria Luisa Garcia-Romeu
Keyword(s):  
Molecular Weight ◽  
Crystallization Rate ◽  
Raw Material ◽  
Small Particle Size ◽  
Polymer Mixtures ◽  
Crystallinity Degree ◽  
Correct Determination ◽  
Production Stages ◽  
Process Speed

Ultrasonic molding (USM) is a good candidate for studying the plasticization of polymer mixtures or other composite materials due to either the little amount of material needed for processing, low waste or the needed low pressure and residence time of the mold. Thus, the novelty of this research is the capability of USM technology to process PLA/PCL blends and their corresponding neat materials, encompassing all the production stages, from raw material to the final specimen. The major findings of the work revealed that the thermal properties of the blends were not affected by the USM process, although the crystallinity degree experienced variations, decreasing for PLA and increasing for PCL, which was attributed to the crystallization rate of each polymer, the high process speed, the short cooling time and the small particle size. The employed ultrasonic energy increased the molecular weight with low variations through the specimen. However, the degradation results aligned with the expected trend of these material blends. Moreover, this study also showed the effect pellet shape and dimensions have over the process parameters, as well as the effect of the blend composition. It can be concluded that USM is a technology suitable to successfully process PLA/PCL blends with the correct determination of process parameter windows.

Finite Element Model to Predict the Bioconversion Rate of Glucose to Fructose using Escherichia coli K12 for Sugar Production from Date

2015 ◽  
Vol 11 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Maher Trigui ◽  
Karim Gabsi ◽  
Walid Zneti ◽  
Suzelle Barrington ◽  
Ahmed Noureddine Helal
Keyword(s):  
Escherichia Coli ◽  
Induction Time ◽  
Volume Fraction ◽  
Element Model ◽  
Initial Concentration ◽  
Computational Fluids Dynamics ◽  
Date Syrup ◽  
Computational Fluids ◽  
Two Phases ◽  
Inoculum Volume

Abstract In this study, Bioconversion process of glucose to fructose from date syrup using Escherichia coli K12 is modeled using a commercial computational fluids dynamics (CFD) code fluent FLUENT 6.3.23 [8] which we implemented a user-defined functions (UDF) to simulate the interrelationships at play between various phases. A two phases CFD model was developed using an Eulerian – Eulerian approach to calculate the fructose volume fraction produced during time. The bioconversion process was studied as function of three initial concentration of glucose (0.14, 0.242 and 0.463gL–1), three induction time (60, 120 and 180 mn) and three inoculum volume (100, 120 and 150mL). The numerical results are compared with experimental data for bioconversion rate and show good agreement (R2= 0.894). The optimal condition of diffusion was obtained by applying an initial concentration of glucose less than 0.2gL–1 and induction time great than 100 minutes.

Anisotropic Guest Diffusion in the δ Crystalline Host Phase of Syndiotactic Polystyrene:  Transport Kinetics in Films with Three Different Uniplanar Orientations of the Host Phase

2006 ◽  
Vol 18 (9) ◽  
pp. 2205-2210 ◽  
Author(s):  
Vincenzo Venditto ◽  
Anna De Girolamo Del Mauro ◽  
Giuseppe Mensitieri ◽  
Giuseppe Milano ◽  
Pellegrino Musto ◽  
...  
Keyword(s):  
Transport Kinetics ◽  
Syndiotactic Polystyrene
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