Investigating the effect of the aging process on LDPE composites with UV protective additives

2020 ◽  
pp. 089270572094190
Author(s):  
Sabih Ovalı ◽  
Erhan Sancak
Keyword(s):  
Mechanical Properties ◽  
Composite Structures ◽  
Color Change ◽  
Accelerated Aging ◽  
Physical And Mechanical Properties ◽  
Ultraviolet Rays ◽  
Color Changes ◽  
Matrix Production ◽  
Ldpe Composites ◽  
Harmful Effects

The contact with ultraviolet rays coming from sunlight causes color changes and deterioration in the main chain structures of composites in outdoor applications and affects the physical and mechanical properties of composite materials negatively. Photodegradation can be slowed and the mechanical strength of composite structures can be improved with adding photostabilizers in polymer matrix production. In this study, we modified low-density polyethylene (LDPE) polymer with an amine light stabilizer (Chimassorb 944), a light absorbent (Tinuvin 326), and an antioxidant (Irganox 1010) and then reinforced with jute fabric (JF). We examined the effect of protective additives, which are used to reduce the harmful effects of sunlight, on JF-reinforced LDPE composites. The color change, physical, and mechanical properties of the composites were determined after 120- and 240-h accelerated aging processes. The results indicate that both the antioxidants and the amine light stabilizers were more effective photostabilizers for JF-reinforced LDPE composites than the absorbents.

scholarly journals Influence of temperature on physical and mechanical properties of a sedimentary rock: Coal measure mudstone

2019 ◽  
pp. 297-297
Author(s):  
Yuan Zhang ◽  
Zhijun Wan ◽  
John McLennan ◽  
Bin Gu ◽  
TA Xupeng
Keyword(s):  
Mechanical Properties ◽  
Clay Minerals ◽  
Color Change ◽  
Physical And Mechanical Properties ◽  
Phase Changes ◽  
Coal Measure ◽  
Water Evaporation ◽  
X Rays ◽  
Color Changes ◽  
Deep Rock

Determining the physical and mechanical behavior of sedimentary rocks is one of the most common challenges in deep rock mass engineering. Experiments were conducted to study the physical and mechanical properties of coal measure mudstone with scanning electron microscope, x-rays diffraction and uniaxial compression testing. The results show that temperature has a significant effect on the physical and mechanical properties of coal measure mudstone. The presence of clay minerals in the evaluated mudstone contributes to the unique characteristics seen at high temperature. The mudstone experiences obvious color changes on the surface as temperature rises. This is mostly attributed to the iron-bearing clay minerals. Internal color change is caused by thermal decomposition of kerogen associated with the clay minerals. As the major clay mineral in mudstone, kaolinite undergoes significant phase changes at high temperatures, which leads to changes in mechanical properties. From 25? to 200 ?, due to the evaporation of absorbed water from the clay minerals, the strength of the mudstone increases significantly. As the temperature continues to rise beyond this, water evaporation continues and the rock strength increases gradually from 200? to 400 ?. When the temperature reaches 400 ?, this mudstone was strengthened as a result of decomposition of the kaolinite and thermal expansion of crystalline minerals. Above 600?, dehydration of the clay minerals ends while thermal cracking initiates gradually, which results in decreasing strength.

Evaluation of Color Changes of Different Resin Cements in Feldspathic Ceramic Crowns After Accelerated Aging: An In Vitro Research

2021 ◽  
pp. 232020682110443
Author(s):  
Murat Eskitaşçıoğlu ◽  
Mehmet Şerif Akdeniz ◽  
Beyza Ünalan Değirmenci
Keyword(s):  
Color Change ◽  
Accelerated Aging ◽  
B Value ◽  
Resin Cements ◽  
Color Changes ◽  
A Value ◽  
L Value ◽  
Ceramic Crowns ◽  
The Times

Aims: To evaluate the color changes that occur after accelerated aging in feldspathic ceramic crowns cemented with three different dual-cured resin cements. Materials and Methods: For each of the A2-colored RelyX U200, G-CEM LinkForce, and Panavia V5 cement groups, 45 dies from A2-colored zirconia blocks and 45 crowns from CEREC blocks were prepared. Color measurements after 24 h of cementation (T1) and after cycles of aging of 1750 (T2), 3500 (T3), and 7000 (T4) in the thermal cycle device were made using SpectroShade Micro device. The coordinates of the color were used L*, a*, and b* as base and the color change was calculated with ∆ E00 in determining the color. One-way analysis of variance test was used to compare the times in terms of ∆ L*, ∆ a*, and ∆ b* values. Results: It was found that ∆ L* value decreased significantly in period of the T2, T3, and T4 times compared to T1 in all groups ( P < .05), whereas the change between period of T2, T3, and T4 times was not significant ( P > .05). The ∆ a* value increased significantly in the period of T3 and T4 times compared to T1 in the only G-CEM LinkForce group, whereas the ∆ b* value increased significantly in the period of T4 time compared to T1 in the only Panavia V5 group. The changes in ∆ E00 values, which were observed in all period of times, were found to be between 0.43 and 1.04, 0.43 and 1.43, and 0.40 and 0.97 in RelyX U200, G-CEM LinkForce, and Panavia V5 groups, respectively. Conclusion: After accelerated aging, it was found that the color of all cements became darker and the G-CEM LinkForce group turned red and the Panavia V5 group turned yellow. However, it was found that the color changes that occurred were within clinically acceptable visible levels.

Prediction of physical and mechanical properties of thermally modified wood based on color change evaluated by means of “group method of data handling” (GMDH) neural network

Holzforschung ◽  
2019 ◽  
Vol 73 (4) ◽  
pp. 381-392 ◽  
Author(s):  
Vahid Nasir ◽  
Sepideh Nourian ◽  
Stavros Avramidis ◽  
Julie Cool
Keyword(s):  
Neural Network ◽  
Mechanical Properties ◽  
Color Change ◽  
Physical And Mechanical Properties ◽  
Group Method ◽  
Data Handling ◽  
Color Parameters ◽  
Swelling Coefficient ◽  
Thermally Modified Wood ◽  
Modified Wood

AbstractThe effect of thermal modification (TM) on the color of western hemlock wood and its physical and mechanical properties were investigated. The focus of this study was the prediction of material properties of thermally modified wood based on the color change via the “group method of data handling (GMDH)” neural network (NN). The NN was trained by color parameters for predicting the equilibrium moisture content (EMC), density, porosity, water absorption (WA), swelling coefficient, dynamic modulus of elasticity (MOEdyn) and hardness. The color parameters showed a significant correlation with temperature and are well correlated with the heat treatment (HT) intensity. Color parameters combined with the GMDH-type NN successfully predicted the physical properties of the material. The best correlation was achieved with the swelling coefficient, EMC and WA. All these properties were significantly influenced by HT. The color parameters did not seem suitable for predicting the wood hardness and MOEdyn. The GMDH NN shows a higher model accuracy than the multivariate linear and partial least squares (PLS) regression models.

Using biopolymers to strengthen the historical printed paper: mechanical and optical characters

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wafika Noshy ◽  
Rushdya Rabee Ali Hassan ◽  
Nada Mohammed
Keyword(s):  
Mechanical Properties ◽  
Design Methodology ◽  
Hydroxypropyl Methylcellulose ◽  
Accelerated Aging ◽  
Hydroxyethyl Cellulose ◽  
Content Type ◽  
Oxidation Processes ◽  
Color Changes ◽  
Dramatic Difference ◽  
Historical Samples

Purpose This study aims to restore the lost mechanical properties of the prints with carrageenan, methyl hydroxyethyl cellulose (Tylose) and hydroxypropyl methylcellulose (Methocel). Design/methodology/approach The effect of these materials on the properties of the printed paper (modern and historical samples) has been evaluated under the influence of accelerated aging using pH measurement, the mechanical properties (tensile and elongation), FTIR and color changes. Findings The three consolidates reduced the acidity of treated samples significantly, but after ageing, it was observed that the pH of aged treated samples decreased slightly as compared to the untreated samples. The results of the mechanical properties showed the superiority of hydroxypropyl methylcellulose (Methocel) in improving the tensile and elongation forces of the samples compared to carrageenan and methyl hydroxyethyl cellulose even during the accelerated aging. Consolidation materials succeeded in reducing ΔE of the paper samples under accelerated aging, especially carrageenan. The IR spectra confirmed that no dramatic difference was observed in topically function vibrations of samples after treatment beside that the O-H stretching band intensity increased observably after treatment with the three consolidates, after ageing the treatment, and it protected the treated paper from oxidation processes as the infrared spectrum analysis showed a decrease in intensities of carbonyl and carboxyl groups as compared to aged untreated samples. Originality/value The research provides new biopolymers in strengthening the historical printed paper, where printed papers lack studies related to their conservation. This makes the current study a promising step for treating historical printed paper.

Construction board resistance to accelerated aging

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2680-2690
Author(s):  
Radosław Mirski ◽  
Adam Derkowski ◽  
Dorota Dziurka
Keyword(s):  
Mechanical Properties ◽  
Relative Humidity ◽  
Construction Industry ◽  
Accelerated Aging ◽  
Physical And Mechanical Properties ◽  
Cyclic Test ◽  
Test Cycle ◽  
Dimensional Changes

Physical and mechanical properties were evaluated for industrial and laboratory boards intended to be used in the construction industry. The boards were subjected to accelerated aging tests including resistance to humidity in the conditions of cyclic test in accordance with EN 321 (2002), and determination of dimensional changes resulting from changes in relative humidity according to EN 318 (2002). The greatest changes were observed after one test cycle. Moreover, the boards made of fine chips demonstrated slightly higher resistance to the tested factors. Although laboratory boards showed a much lower density, their behavior following the exposure to the assessed factors was similar to that of industrial plates.

scholarly journals Polyolefin/ZnO Composites Prepared by Melt Processing

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2432
Author(s):  
Alojz Anžlovar ◽  
Mateja Primožič ◽  
Iztok Švab ◽  
Maja Leitgeb ◽  
Željko Knez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Antibacterial Activity ◽  
Color Change ◽  
Antibacterial Properties ◽  
Melt Processing ◽  
Degree Of Crystallinity ◽  
Mechanical And Thermal Properties ◽  
Nano Zno ◽  
Color Changes ◽  
Zno Powders

Composites of polyolefin matrices (HDPE and PP) were prepared by melt processing using two commercially available nano ZnO powders (Zinkoxyd aktiv and Zano 20). The mechanical and thermal properties, UV-Vis stability, and antibacterial activity of composites were studied. Tensile testing revealed that both nano ZnO types have no particular effect on the mechanical properties of HDPE composites, while some positive trends are observed for the PP-based composites, but only when Zano 20 was used as a nanofiller. Minimal changes in mechanical properties of composites are supported by an almost unaffected degree of crystallinity of polymer matrix. All polyolefin/ZnO composites exposed to artificial sunlight for 8–10 weeks show more pronounced color change than pure matrices. This effect is more evident for the HDPE than for the PP based composites. Color change also depends on the ZnO concentration and type; composites with Zano 20 show more intense color changes than those prepared with Zinkoxyd aktiv. Results of the antibacterial properties study show very high activity of polyolefin/ZnO composites against Staphylococcus aureus regardless of the ZnO surface modification, while antibacterial activity against Escherichia coli shows only the composites prepared with unmodified ZnO. This phenomenon is explained by different membrane structure of gram-positive (S. aureus) and gram-negative (E. coli) bacteria.

Photostabilizers performance on the surface analysis of green composites

2020 ◽  
Vol 29 (1) ◽  
pp. 57-64
Author(s):  
Hasret Ece Sönmez ◽  
Mehmet Safa Bodur ◽  
Alper Adrian Baysan ◽  
Mustafa Bakkal ◽  
Ersin Serhatli
Keyword(s):  
Surface Analysis ◽  
Color Change ◽  
Uv Light ◽  
Light Exposure ◽  
Accelerated Weathering ◽  
Reinforced Composites ◽  
Color Changes ◽  
Photodegradation Mechanism ◽  
Ldpe Composites

In this work, various stabilizers have been introduced to prevent or delay degradation due to ultraviolet (UV) light exposure to prolong the service life of cotton fiber-reinforced composites. The effect of various additives like hindered amine light stabilizer, UV absorber (UVA), and antioxidant as photostabilizers of CF/low-density polyethylene (CF/LDPE) composites was compared. We showed how they influence to delay or eliminate the photodegradation of CF/LDPE subjected accelerated weathering. Surface analysis was performed by Fourier transform infrared spectroscopy and color measurements. The results showed us the insight of the photodegradation mechanism of weathered CF/LDPE composites undergoing photooxidative reactions which causes a loss surface quality such as micro-cracking and color change. Among the stabilizers, UVA was found to be the most effective to delay some color changes in long term.

scholarly journals Evaluation of staining and color changes of a resin infiltration system

2016 ◽  
Vol 86 (6) ◽  
pp. 900-904 ◽  
Author(s):  
Andrew Leland ◽  
Sercan Akyalcin ◽  
Jeryl D. English ◽  
Eser Tufekci ◽  
Rade Paravina
Keyword(s):  
Red Wine ◽  
Color Change ◽  
Accelerated Aging ◽  
Color Difference ◽  
Human Teeth ◽  
Point Pair ◽  
Resin Infiltration ◽  
Color Changes ◽  
The Right ◽  
Time Point

ABSTRACT Objective: To analyze the staining and color changes of a resin infiltrant system used for management of white spot lesions (WSLs). Materials and Methods: WSLs were artificially created on left buccal halves of 48 extracted human teeth. These sites were then treated with resin infiltration (RI) while the right halves of the teeth remained as nonresin (NRI) areas. Six groups were formed (n = 8 teeth/group) and were exposed to the following: red wine, coffee, orange juice, combined staining agents, accelerated aging, and distilled water for 1 week. The teeth were then polished with a prophy cup and polishing paste. Color properties were assessed using a spectrophotometer at baseline (T0), after each exposure (T1), and after polishing (T2). Color difference (ΔE*) was calculated between each time point for both halves of the teeth (RI and NRI). Data were analyzed with a two-way analysis of variance with presence of resin infiltration and staining agents as the main effects for each time point pair. Multiple comparisons were made with a Bonferroni post hoc test. The level of significance was set at P &lt; .05. Results: The red wine and combined staining agent groups caused the greatest color change between all intervals (P &lt; .05). Significant interactions were recorded between resin infiltration application and staining agents at all time periods (P &lt; .05). The presence of resin infiltration as a main effect did not affect color change between T0 and T2 (P &gt; .05). Conclusions: RI areas showed higher staining susceptibility than did NRI areas. However, prophylaxis had a strong effect on reversing the discoloration of both RI and NRI areas.

scholarly journals Application of Earth Pigments in Cycloolefin Copolymer: Protection against Combustion and Accelerated Aging in the Full Sunlight Spectrum

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3381
Author(s):  
Bolesław Szadkowski ◽  
Małgorzata Kuśmierek ◽  
Przemysław Rybiński ◽  
Witold Żukowski ◽  
Anna Marzec
Keyword(s):  
Mechanical Properties ◽  
Surface Defects ◽  
Accelerated Aging ◽  
Carbonyl Index ◽  
Full Sunlight ◽  
Color Changes ◽  
Aging Resistance ◽  
Mixing Method ◽  
Enhanced Photostability ◽  
Aging Factor

In this paper, we assess various natural earth pigments as potential colorants and stabilizers for ethylene–norbornene copolymer composites. Several cycloolefin copolymer (COC) composites colored with 2 wt% of a selected pigment were prepared using a two-step mixing method. The aging resistance of the polymer composites was investigated in terms of changes to their mechanical properties, following accelerated aging in the full sunlight spectrum (100, 200, 300, 400, and 500 h). Fourier-transform infrared spectroscopy (FTIR), surface energy measurements, and spectrophotometry were used to assess the color changes, surface defects, and morphology of the composites. Thermogravimetric analysis (TGA) was used to study their thermal stability. The combustion characteristics of the prepared COC composites were evaluated based on the microcombustion calorimetry test (MCC). The application of earth pigments resulted in interesting color changes and a significant improvement in the aging resistance of the COC-filled samples, as evidenced by higher aging factor values and lower carbonyl index parameters compared to the reference (COC). The best results were observed for hematite (HM), gold ochre (GO), and red ochre (RO). In addition, the application of earth pigments, especially iron ochre (IO) and red ochre (RO), in COC contributed to a significant reduction in the heat release rate (HRR) values, indicating improved flame retardancy. This research opens the possibility of producing colorful COC composites with enhanced photostability and reduced flammability for use in polymer applications.

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