scholarly journals Gum Rosin as A Size Control Agent of Poly(Butylene Adipate-Co-Terephthalate) (PBAT) Domains to Increase the Toughness of Packaging Formulations Based on Polylactic Acid (PLA)

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1913
Author(s):  
Miguel Aldas ◽  
José Miguel Ferri ◽  
Dana Luca Motoc ◽  
Laura Peponi ◽  
Marina Patricia Arrieta ◽  
...  
Keyword(s):  
Polylactic Acid ◽  
Food Packaging ◽  
Impact Resistance ◽  
Size Control ◽  
Control Agent ◽  
Scanning Calorimetry ◽  
Transparent Films ◽  
Gum Rosin ◽  
And Control ◽  
The Impact

Gum rosin (GR) was used as a natural additive to improve the compatibility between polylactic acid, PLA, and poly(butylene adipate-co-terephthalate, PBAT, blended with 20 wt.% of PBAT (PLA/PBAT). The PBAT was used as a soft component to increase the ductility of PLA and its fracture toughness. The coalescence of the PBAT domains was possible due to the plasticization effect of the GR component. These domains contributed to increasing the toughness of the final material due to the variation and control of the PBAT domains’ size and consequently, reducing the stress concentration points. The GR was used in contents of 5, 10, 15, and 20 phr. Consequently, the flexural properties were improved and the impact resistance increased up to 80% in PLA/PBAT_15GR with respect to the PLA/PBAT formulation. Field emission scanning electron microscope (FESEM) images allowed observing that the size of PBAT domains of 2–3 µm was optimal to reduce the impact stress. Differential scanning calorimetry (DSC) analysis showed a reduction of up to 8 °C on the PLA melting temperature and up to 5.3 °C of the PLA glass transition temperature in the PLA/PBAT_20GR formulation, which indicates an improvement in the processability of PLA. Finally, transparent films with improved oxygen barrier performance and increased hydrophobicity were obtained suggesting the potential interest of these blends for the food packaging industry.

Modification of Polylactic Acid/ Halloysite Bionanocomposites Using Electron Beam Radiation: Physical, Barrier and Thermal Properties

2020 ◽  
Vol 1002 ◽  
pp. 57-65
Author(s):  
Abdulkader M. Alakrach ◽  
Nik Noriman Zulkepli ◽  
Awad A. Al-Rashdi ◽  
Sam Sung Ting ◽  
Rosniza Hamzah ◽  
...  
Keyword(s):  
Electron Beam ◽  
Polylactic Acid ◽  
Food Packaging ◽  
Electron Beam Irradiation ◽  
Casting Process ◽  
Barrier Properties ◽  
Beam Irradiation ◽  
Beam Radiation ◽  
Electron Beam Processing ◽  
The Impact

This study aimed to develop novel Polylactic acid/ Halloysite (PLA/ HNTs) films which showed better properties when they were used for food packaging. They also displayed better mechanical, barrier, morphological and structural properties when the researchers analysed the impact of the electron beam irradiation on the nanomaterials. They prepared PLA-based nanocomposites containing 5 % w/w of HNTs using the solution casting process. These nanocomposites were further exposed to different ebeam doses (i.e., 0, 20, 40 and 60 kGy). The researchers assessed the effect of the electron beam irradiation on the various properties of the PLA. All the composites showed a homogenous dispersion and distribution of the HNTs in this PLA matrix. Results indicated that the nanocomposites showed better barrier properties in comparison to the neat PLA. Furthermore, the ebeam irradiation could increase the glass-transition temperature and lead to the development of more crosslinks, which increased the degradation temperature and hydrophilicity of the nanocomposites. In this study, the researchers showed that the PLA/HNTs films were effective materials that could be used for the electron beam processing of the pre-packed foods. The best effect was noted for the 20 kGy dosage which was used in the study.

scholarly journals Resistance to Cleavage of Core–Shell Rubber/Epoxy Composite Foam Adhesive under Impact Wedge–Peel Condition for Automobile Structural Adhesive

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 152 ◽  
Author(s):  
Jong-Ho Back ◽  
Dooyoung Baek ◽  
Jae-Ho Shin ◽  
Seong-Wook Jang ◽  
Hyun-Joong Kim ◽  
...  
Keyword(s):  
Pore Size ◽  
Epoxy Composite ◽  
Impact Resistance ◽  
Expansion Ratio ◽  
Core Shell ◽  
Scanning Calorimetry ◽  
Composite Foam ◽  
Foaming Agent ◽  
Epoxy Foam ◽  
The Impact

Epoxy foam adhesives are widely used for weight reduction, watertight property, and mechanical reinforcement effects. However, epoxy foam adhesives have poor impact resistance at higher expansion ratios. Hence, we prepared an epoxy composite foam adhesive with core–shell rubber (CSR) particles to improve the impact resistance and applied it to automotive structural adhesives. The curing behavior and pore structure were characterized by differential scanning calorimetry (DSC) and X-ray computed tomography (CT), respectively, and impact wedge–peel tests were conducted to quantitatively evaluate the resistance to cleavage of the CSR/epoxy composite foam adhesives under impact. At 5 and 10 phr CSR contents, the pore size and expansion ratio increased sufficiently due to the decrease in curing rate. However, at 20 phr CSR content, the pore size decreased, which might be due to the steric hindrance effect of the CSR particles. Notably, at 0 and 0.1 phr foaming agent contents, the resistance to cleavage of the adhesives under the impact wedge–peel condition significantly improved with increasing CSR content. Thus, the CSR/epoxy composite foam adhesive containing 0.1 phr foaming agent and 20 phr CSR particles showed high impact resistance (EC = 34,000 mJ/cm2) and sufficient expansion ratio (~148%).

scholarly journals Functionalization of silica particles to tune the impact resistance of shear thickening fluid treated aramid fabrics

RSC Advances ◽  
2017 ◽  
Vol 7 (78) ◽  
pp. 49787-49794 ◽  
Author(s):  
K. Talreja ◽  
I. Chauhan ◽  
A. Ghosh ◽  
A. Majumdar ◽  
B. S. Butola
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Impact Resistance ◽  
Shear Thickening ◽  
Silica Particles ◽  
Modified Silica ◽  
Shear Thickening Fluid ◽  
Aramid Fabrics ◽  
And Control ◽  
The Impact

Kevlar fabrics treated with MTMS modified silica based STF showed better impact energy absorption as compared to APTES modified and control silica based STF treated fabrics, attributed to changes in interactions between fabrics and silica particles.

scholarly journals Degradation of Polylactic Acid Using Sub-Critical Water for Compost

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2434
Author(s):  
Toshiharu Goto ◽  
Mikitaka Kishita ◽  
Yin Sun ◽  
Takeshi Sako ◽  
Idzumi Okajima
Keyword(s):  
Molecular Weight ◽  
Polylactic Acid ◽  
Food Packaging ◽  
Crystallization Rate ◽  
General Purpose ◽  
Water Soluble ◽  
Decomposition Rates ◽  
Scanning Calorimetry ◽  
Reaction Conditions ◽  
Decomposition Products

Polylactic acid (PLA) is expected to replace many general-purpose plastics, especially those used for food packaging and agricultural mulch. In composting, the degradation speed of PLA is affected by the molecular weight, crystallinity, and microbial activity. PLA with a molecular weight of less than 10,000 has been reported to have higher decomposition rates than those with higher molecular weight. However, PLA degradation generates water-soluble products, including lactic acid, that decrease the pH of soil or compost. As acidification of soil or compost affects farm products, their pH should be controlled. Therefore, a method for determining suitable reaction conditions to achieve ideal decomposition products is necessary. This study aimed to determine suitable reaction conditions for generating preprocessed PLA with a molecular weight lower than 10,000 without producing water-soluble contents. To this end, we investigated the degradation of PLA using sub-critical water. The molecular weight and ratio of water-soluble contents (WSCs) affecting the pH of preprocessed products were evaluated through kinetic analysis, and crystallinity was analyzed through differential scanning calorimetry. Preprocessed PLA was prepared under the determined ideal conditions, and its characteristics in soil were observed. The results showed that the crystallization rate increased with PLA decomposition but remained lower than 30%. In addition, the pH of compost mixed with 40% of preprocessed PLA could be controlled within pH 5.4–5.5 over 90 days. Overall, soil mixed with the preprocessed PLA prepared under the determined ideal conditions remains suitable for plant growth.

Effectiveness assessment of TiO2-Al2O3 nano-mixture as a filler material for improvement of packaging performance of PLA nanocomposite films

2020 ◽  
Vol 40 (10) ◽  
pp. 848-858
Author(s):  
Fatima Zohra Yakdoumi ◽  
Assia Siham Hadj-Hamou
Keyword(s):  
Polylactic Acid ◽  
Nanocomposite Film ◽  
Food Packaging ◽  
Antimicrobial Properties ◽  
Young Modulus ◽  
Nanocomposite Films ◽  
Vapor Permeability ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Vis Spectroscopy

AbstractThe main objective of this study was to assess the effectiveness of TiO2-Al2O3 nano-mixture used as filler in improving packaging films performance. Polylactic acid/titanium dioxide (PLA/TiO2), polylactic acid/alumina (PLA/Al2O3) and polylactic acid/TiO2-Al2O3 (PLA/TiO2-Al2O3) nanocomposite films were successfully prepared via melt mixing process and thoroughly characterized by FTIR spectroscopy, X-ray diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The properties such as heat resistant, barrier, mechanical and antimicrobial properties, required for food packaging have also been investigated. As compared to the neat PLA film, the developed PLA nanocomposites have displayed superior properties particularly the PLA/ TiO2-Al2O3 nanocomposite film. This resulted material has showed a 22 °C increase in its thermal stability versus 14 and 2 °C in the cases of PLA/TiO2 and PLA/Al2O3 respectively, and a 54% reduction of its water vapor permeability in comparison with 47% for PLA/TiO2 and 39% for PLA/Al2O3. In addition, the PLA/TiO2-Al2O3 had a significant enhancement of its mechanical properties. Its Young modulus increased by 102% unlike 23.60% for the PLA/TiO2 and 44.66% for the PLA/Al2O3. It was also noticed that this nanocomposite film demonstrated stronger antibacterial activity than the two others. The bacterial growth inhibition effect of TiO2-Al2O3 nano-mixture against Pseudomonas aeruginosa and Escherichia coli bacteria was more effective than that of its two constituents.

scholarly journals Properties of epoxy-thiokol materials based on the products of the preliminary reaction of thioetherification

2021 ◽  
pp. 128-136
Author(s):  
K.M. Sukhyy ◽  
◽  
E.A. Belyanovskaya ◽  
A.N. Nosova ◽  
M.K. Sukhyy ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Adhesive Strength ◽  
Impact Resistance ◽  
Maximum Level ◽  
Scanning Calorimetry ◽  
Mechanical Mixtures ◽  
The Impact ◽  
Fracture Work ◽  
Specific Impact

In order to improve the adhesive and physical-mechanical properties of epoxy-thiocol compositions cured without heat treatment, we propose to carry out the reaction of interaction between thiokol mercaptan groups and oxirane cycles of epoxy resin at an elevated temperature before introducing a curing agent, and then use the product of this thioetherification reaction for curing at room temperature. The temperature range of the thioetherification reaction (90–1800С) was determined by the method of differential scanning calorimetry. The optimal temperature (1600С) and duration of the preliminary thioetherification reaction (2 hours) were determined, which ensure the maximum level of adhesive strength and physical-mechanical properties. It was shown that composite materials based on the products of the thioetherification reaction significantly outperform analogs based on mechanical mixtures of epoxy resin and thiokol in terms of cohesive and adhesive strength, deformation capacity, fracture work and specific impact strength. The impact resistance and shear strength of adhesive joints are especially significantly increased during the curing of the compositions without external heat supply.

scholarly journals Modified Polylactic Acid with Improved Impact Resistance in the Presence of a Thermoplastic Elastomer and the Influence of Fused Filament Fabrication on Its Physical Properties

2021 ◽  
Vol 5 (9) ◽  
pp. 232
Author(s):  
Samir Kasmi ◽  
Julien Cayuela ◽  
Bertrand De Backer ◽  
Eric Labbé ◽  
Sébastien Alix
Keyword(s):  
Polylactic Acid ◽  
Impact Resistance ◽  
Thermoplastic Elastomer ◽  
Mechanical And Thermal Properties ◽  
Fused Filament Fabrication ◽  
Crystallinity Degree ◽  
Elongation At Break ◽  
Industrial Sectors ◽  
The Impact ◽  
Printing Parameters

The standard polylactic acid (PLA), as a biodegradable thermoplastic polymer, is commonly used in various industrial sectors, food, and medical fields. Unfortunately, it is characterized by a low elongation at break and low impact energy. In this study, a thermoplastic copolyester elastomer (TPCE) was added at different weight ratios to improve the impact resistance of PLA. DSC analysis revealed that the two polymers were immiscible. A good balance of impact resistance and rigidity was reached using the formulation that was composed of 80% PLA and 20% TPCE, with an elongation at break of 155% compared to 4% for neat PLA. This new formulation was selected to be tested in a fused filament fabrication process. The influence of the nozzle and bed temperatures as printing parameters on the mechanical and thermal properties was explored. Better impact resistance was observed with the increase in the two thermal printing parameters. The crystallinity degree was not influenced by the variation in the nozzle temperature. However, it was increased at higher bed temperatures. Tomographic observations showed an anisotropic distribution of the porosity, where it was mostly present between the adjacent printed filaments and it was reduced with the increase in the nozzle and bed temperatures.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Research Participation Experiences of Informants of Suicide and Control Cases

Crisis ◽  
2010 ◽  
Vol 31 (5) ◽  
pp. 238-246 ◽  
Author(s):  
Paul W. C. Wong ◽  
Wincy S. C. Chan ◽  
Philip S. L. Beh ◽  
Fiona W. S. Yau ◽  
Paul S. F. Yip ◽  
...  
Keyword(s):  
Ethical Issues ◽  
Research Participation ◽  
Self Report ◽  
Initial Contact ◽  
Psychological Autopsy ◽  
Autopsy Study ◽  
The People ◽  
And Control ◽  
The Impact

Background: Ethical issues have been raised about using the psychological autopsy approach in the study of suicide. The impact on informants of control cases who participated in case-control psychological autopsy studies has not been investigated. Aims: (1) To investigate whether informants of suicide cases recruited by two approaches (coroners’ court and public mortuaries) respond differently to the initial contact by the research team. (2) To explore the reactions, reasons for participation, and comments of both the informants of suicide and control cases to psychological autopsy interviews. (3) To investigate the impact of the interviews on informants of suicide cases about a month after the interviews. Methods: A self-report questionnaire was used for the informants of both suicide and control cases. Telephone follow-up interviews were conducted with the informants of suicide cases. Results: The majority of the informants of suicide cases, regardless of the initial route of contact, as well as the control cases were positive about being approached to take part in the study. A minority of informants of suicide and control cases found the experience of talking about their family member to be more upsetting than expected. The telephone follow-up interviews showed that none of the informants of suicide cases reported being distressed by the psychological autopsy interviews. Limitations: The acceptance rate for our original psychological autopsy study was modest. Conclusions: The findings of this study are useful for future participants and researchers in measuring the potential benefits and risks of participating in similar sensitive research. Psychological autopsy interviews may be utilized as an active engagement approach to reach out to the people bereaved by suicide, especially in places where the postvention work is underdeveloped.

Using Work Domain Analysis to Evaluate the Impact of Digitization on Command and Control

2008 ◽  
Author(s):  
Daniel P. Jenkins ◽  
Neville A. Stanton ◽  
Paul M. Salmon ◽  
Guy H. Walker
Keyword(s):  
Command And Control ◽  
Domain Analysis ◽  
Work Domain Analysis ◽  
And Control ◽  
The Impact ◽  
Work Domain
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