scholarly journals Influence of Controlled Epoxidation of an Asymmetric Styrene/Butadiene Star Block Copolymer on Structural and Mechanical Properties

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 96
Author(s):  
Shankar P. Khatiwada ◽  
Ulrike Staudinger ◽  
Dieter Jehnichen ◽  
Gert Heinrich ◽  
Rameshwar Adhikari

The chemical modification (namely the epoxidation) of a star shaped block copolymer (BCP) based on polystyrene (PS) and polybutadiene (PB) and its effect on structural and mechanical properties of the polymer were investigated. Epoxidation degrees of 37 mol%, 58 mol%, and 82 mol% were achieved by the reaction of the copolymer with meta-chloroperoxy benzoic acid (m-CPBA) under controlled conditions. The BCP structure was found to change from lamellae-like to mixed-type morphologies for intermediate epoxidation level while leading to quite ordered cylindrical structures for the higher level of chemical modification. As a consequence, the glass transition temperature (Tg) of the soft PB component of the BCP shifted towards significantly higher temperature. A clear increase in tensile modulus and tensile strength with a moderate decrease in elongation at break was observed. The epoxidized BCPs are suitable as reactive templates for the fabrication of nanostructured thermosetting resins.

Author(s):  
Ivanna Baturynska

Additive manufacturing (AM) is an attractive technology for manufacturing industry due to flexibility in design and functionality, but inconsistency in quality is one of the major limitations that does not allow utilizing this technology for production of end-use parts. Prediction of mechanical properties can be one of the possible ways to improve the repeatability of the results. The part placement, part orientation, and STL model properties (number of mesh triangles, surface, and volume) are used to predict tensile modulus, nominal stress and elongation at break for polyamide 2200 (also known as PA12). EOS P395 polymer powder bed fusion system was used to fabricate 217 specimens in two identical builds (434 specimens in total). Prediction is performed for XYZ, XZY, ZYX, and Angle orientations separately, and all orientations together. The different non-linear models based on machine learning methods have higher prediction accuracy compared with linear regression models. Linear regression models have prediction accuracy higher than 80% only for Tensile Modulus and Elongation at break in Angle orientation. Since orientation-based modeling has low prediction accuracy due to a small number of data points and lack of information about material properties, these models need to be improved in the future based on additional experimental work.


2017 ◽  
Vol 52 (3) ◽  
pp. 167-176 ◽  
Author(s):  
AK Mondal ◽  
PK Chattopadhyay

Four different bag leathers, such as, Sheep Bag Leather (SBL), Buffalo Vegetable Tanned Leather (BVTL), Cow Drum Dyed Dry Milled Leather (CDDDML), and Cow Crocodile Print Leather (CCPL), were processed by different methods from respective wet-blues of Indian origin. Thermal degradation pro?le and mechanical properties of the samples were evaluated, and crosslink densities of each sample were measured by ?tment of Mooney-Rivlin equation on stress-strain plots. Morphological characteristics (e.g. ?bre structure, ?bre thickness, splitting etc.) of all the specimens were investigated by image analyses of SEM photomicrographs. The highest crosslinking density for BVTL was attributed to its higher ?bre and ?bril thicknesses coupled with rigorous retanning by vegetable tannins and syntans. Embossing at higher temperature and pressure reduced CCPL’s elongation-at-break value and hence stretchiness possibly due to the development of set properties within the CCPL matrix. SBL was noted to contain huge void spaces that increased its stretchiness, and melamine formaldehyde syntans showed pronounced in?uence in increasing the thermal resistance of both CCPL and CDDDML.Bangladesh J. Sci. Ind. Res. 52(3), 167-176, 2017


2019 ◽  
Vol 9 (6) ◽  
pp. 1060
Author(s):  
Ivanna Baturynska

Additive manufacturing (AM) is an attractive technology for the manufacturing industry due to flexibility in its design and functionality, but inconsistency in quality is one of the major limitations preventing utilizing this technology for the production of end-use parts. The prediction of mechanical properties can be one of the possible ways to improve the repeatability of results. The part placement, part orientation, and STL model properties (number of mesh triangles, surface, and volume) are used to predict tensile modulus, nominal stress, and elongation at break for polyamide 2200 (also known as PA12). An EOS P395 polymer powder bed fusion system was used to fabricate 217 specimens in two identical builds (434 specimens in total). Prediction is performed for XYZ, XZY, ZYX, and Angle orientations separately, and all orientations together. The different non-linear models based on machine learning methods have higher prediction accuracy compared with linear regression models. Linear regression models only have prediction accuracy higher than 80% for Tensile Modulus and Elongation at break in Angle orientation. Since orientation-based modeling has low prediction accuracy due to a small number of data points and lack of information about the material properties, these models need to be improved in the future based on additional experimental work.


2003 ◽  
Vol 76 (2) ◽  
pp. 299-317 ◽  
Author(s):  
A. M. Shanmugharaj ◽  
Anil K. Bhowmick

Abstract Rheometric and mechanical properties, hysteresis and swelling behavior of the Styrene-Butadiene Rubber vulcanizates (SBR) filled with unmodified and novel electron beam modified surface treated dual phase fillers were investigated. Scorch time increases for these modified filler loaded vulcanizates due to introduction of quinone type oxygen on the surface. Electron beam modification of dual phase filler in the absence of trimethylol propanetriacrylate (TMPTA) or triethoxysilylpropyltetrasulphide (Si-69) significantly improves the modulus of the SBR vulcanizates, whereas the values of tensile strength and elongation at break drop. However, presence of TMPTA or silane slightly increases the modulus with significant improvement in tensile strength. This effect is more pronounced at higher loading of these modified fillers in SBR vulcanizates. These variations in modulus and tensile strength are explained by the equilibrium swelling data, Kraus plot and a new mathematical model interpreting the polymer-filler interaction. Hysteresis loss ratio of SBR vulcanizates loaded with irradiated fillers in absence and presence of TMPTA or silane increases due to highly aggregated structure of the filler.


2020 ◽  
Author(s):  
Wenfa Dong ◽  
Ruogu Tang

<div>The water industry used NR was selected for blending with SBR. A series of NR/SBR vulcanizates were prepared through three different vulcanization systems, conventional vulcanization (CV), effective vulcanization (EV) and semi-effective vulcanization (SEV) respectively, basing on each formulation and optimum curing time. We examined the mechanical properties of NR/SBR vulcanizates including tensile strength, tear strength, elongation at break, modulus, Shore A hardnessand and relative volume abrasion. The results indicated that NR/SBR vulcanizates prepared in different systems differed in mechanical properties. Vulcanizates prepared via CV showed higher tensile and tear strength; vulcanizates prepared via EV had high modulus and hardness, and vulcanizates prepared via SEV performed high abrasion resistance. </div>


1990 ◽  
Vol 203 ◽  
Author(s):  
Taishih Maw ◽  
Richard E. Hopla

ABSTRACTMechanical properties (tensile modulus, tensile strength, elongation at break), thermal properties (T8' CTE, thermo-decomposition temperature, and rate of weight loss) and electrical properties of Problmlde 414 cured films have been determined. The mechanical properties of Probimide 414 thin films are highly dependent on the hard-bake temperature, hard-bake time, and purge gas, but not dependent on the level of the exposure energy or the presence of 1% Irganox 1010 (w/w) as a stabilizer. At a hard-bake temperature of 350ºC and a nitrogen purge rate of 15 SCFH, Probimide 414 films showed excellent retention of the mechanical properties during extended heat treatment.


2013 ◽  
Vol 834-836 ◽  
pp. 847-854
Author(s):  
Le Lun Jiang ◽  
Yong Huang ◽  
Jin Tian Ling ◽  
Zhang Qi Feng ◽  
Xi Feng Qiao ◽  
...  

PLGA (polylactic-co-glycolic acid) is an ideal material for biodegradable medical suture. PLGA fibers and fiber membrane was prepared by using electrostatic spinning, the surface morphology of PLGA fibers and fiber membranes was observed by SEM, and mechanical properties of PLGA fibers and fiber membranes were tested by self-developed micro-force loading system. Experimental results were found that the arrangement of PLGA fibers due to surface tension and friction between fibers was the main factor on mechanical properties of PLGA fibers. The tensile strength of two fibers in winding arrangement was 1.81 times of fibers arranged in parallel at a given number. The tensile strength of three fibers in winding arrangement was 1.25 times of fibers arranged in parallel at a given number. For 80.6 % porosity and 1.028-5.764 mm width PLGA fiber membranes, tensile strength was 1.06-1.47 MPa, tensile modulus was 9.14-13.6 MPa, and elongation at break was 10.8 % to 11.6 %. The tension of fiber membranes increased with its width.


BioResources ◽  
2010 ◽  
Vol 5 (3) ◽  
pp. 1618-1625
Author(s):  
M. Alamgir Kabir ◽  
M. Monimul Huque ◽  
M. Rabiul Islam ◽  
Andrzej K. Bledzki

Raw jute fiber was treated with o-hydroxybenzenediazonium salt (o-HBDS) in alkaline media. Raw and modified jute fiber were used to prepare composites by mixing with polypropylene (PP) plastic in different weight fractions (20, 25, 30, and 35%) of jute fiber. The mechanical properties except elongation at break of o-HBDS-treated (in alkaline medium) jute fiber-PP composite were higher than those of PP alone, raw jute fiber-PP composites, and alkali-treated jute fiber-PP composites. The elongation at break of treated jute-PP composite decreased to a large extent as compared to that of PP. The increase of tensile strength, tensile modulus, flexural strength, flexural modulus, and Charpy impact strength were found to be exceptionally high (in some cases ~200%) as compared to those of literature values.


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