High modulus filaments of polyethylene with lamellar structure by melt processing; the role of the high molecular weight component

1984 ◽  
Vol 19 (11) ◽  
pp. 3713-3725 ◽  
Author(s):  
Z. Bashir ◽  
J. A. Odell ◽  
A. Keller
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Lamellar Structure ◽  
Melt Processing ◽  
High Modulus ◽  
High Molecular Weight Component

scholarly journals Melt- vs. Non-Melt Blending of Complexly Processable Ultra-High Molecular Weight Polyethylene/Cellulose Nanofiber Bionanocomposite

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 404
Author(s):  
Nur Sharmila Sharip ◽  
Hidayah Ariffin ◽  
Tengku Arisyah Tengku Yasim-Anuar ◽  
Yoshito Andou ◽  
Yuki Shirosaki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
Yield Strength ◽  
Young’S Modulus ◽  
High Molecular Weight ◽  
Melt Processing ◽  
Cellulose Nanofiber ◽  
Melt Blending ◽  
Ultra High Molecular Weight

The major hurdle in melt-processing of ultra-high molecular weight polyethylene (UHMWPE) nanocomposite lies on the high melt viscosity of the UHMWPE, which may contribute to poor dispersion and distribution of the nanofiller. In this study, UHMWPE/cellulose nanofiber (UHMWPE/CNF) bionanocomposites were prepared by two different blending methods: (i) melt blending at 150 °C in a triple screw kneading extruder, and (ii) non-melt blending by ethanol mixing at room temperature. Results showed that melt-processing of UHMWPE without CNF (MB-UHMWPE/0) exhibited an increment in yield strength and Young’s modulus by 15% and 25%, respectively, compared to the Neat-UHMWPE. Tensile strength was however reduced by almost half. Ethanol mixed sample without CNF (EM-UHMWPE/0) on the other hand showed slight decrement in all mechanical properties tested. At 0.5% CNF inclusion, the mechanical properties of melt-blended bionanocomposites (MB-UHMWPE/0.5) were improved as compared to Neat-UHMWPE. It was also found that the yield strength, elongation at break, Young’s modulus, toughness and crystallinity of MB-UHMWPE/0.5 were higher by 28%, 61%, 47%, 45% and 11%, respectively, as compared to the ethanol mixing sample (EM-UHMWPE/0.5). Despite the reduction in tensile strength of MB-UHMWPE/0.5, the value i.e., 28.4 ± 1.0 MPa surpassed the minimum requirement of standard specification for fabricated UHMWPE in surgical implant application. Overall, melt-blending processing is more suitable for the preparation of UHMWPE/CNF bionanocomposites as exhibited by their characteristics presented herein. A better mechanical interlocking between UHMWPE and CNF at high temperature mixing with kneading was evident through FE-SEM observation, explains the higher mechanical properties of MB-UHMWPE/0.5 as compared to EM-UHMWPE/0.5.

scholarly journals The Role of High Molecular Weight Kininogen and Prothrombin as Cofactors in the Binding of Factor XI A3 Domain to the Platelet Surface

2000 ◽  
Vol 275 (33) ◽  
pp. 25139-25145 ◽  
Author(s):  
David H. Ho ◽  
Karen Badellino ◽  
Frank A. Baglia ◽  
Mao-Fu Sun ◽  
Ming-Ming Zhao ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
High Molecular Weight Kininogen ◽  
Factor Xi ◽  
Platelet Surface

scholarly journals Role of Sintering Temperature in Production of Nepheline Ceramics-Based Geopolymer with Addition of Ultra-High Molecular Weight Polyethylene

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1077
Author(s):  
Romisuhani Ahmad ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Wan Mastura Wan Ibrahim ◽  
Kamarudin Hussin ◽  
Fakhryna Hannanee Ahmad Zaidi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Microstructural Properties ◽  
Sintering Process ◽  
Final Microstructure ◽  
Change Of Microstructure ◽  
Ultra High Molecular Weight

The primary motivation of developing ceramic materials using geopolymer method is to minimize the reliance on high sintering temperatures. The ultra-high molecular weight polyethylene (UHMWPE) was added as binder and reinforces the nepheline ceramics based geopolymer. The samples were sintered at 900 °C, 1000 °C, 1100 °C, and 1200 °C to elucidate the influence of sintering on the physical and microstructural properties. The results indicated that a maximum flexural strength of 92 MPa is attainable once the samples are used to be sintered at 1200 °C. It was also determined that the density, porosity, volumetric shrinkage, and water absorption of the samples also affected by the sintering due to the change of microstructure and crystallinity. The IR spectra reveal that the band at around 1400 cm−1 becomes weak, indicating that sodium carbonate decomposed and began to react with the silica and alumina released from gels to form nepheline phases. The sintering process influence in the development of the final microstructure thus improving the properties of the ceramic materials.

scholarly journals The nanostructuring of ultra-high-molecular-weight polyethylene in thermal and mechanical fields as revealed by DSC

2021 ◽  
Vol 2103 (1) ◽  
pp. 012095
Author(s):  
L P Myasnikova ◽  
A K Borisov ◽  
Yu M Boiko ◽  
A P Borsenko ◽  
V F Drobot’ko ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Melting Temperature ◽  
Mechanical Characteristics ◽  
Thickness Distribution ◽  
High Strength ◽  
High Modulus ◽  
Know How ◽  
First Time ◽  
Ultra High Molecular Weight

Abstract The ultra-high-molecular-weight polyethylene reactor powders are widely used for the actively developing solvent-free method for producing high-strength high-modulus PE filaments, which includes the compaction and sintering of a powder followed by orientational hardening. To find an appropriate regime of the technological process, it is important to know how the nanostructure changes when transforming from a powder to a precursor for hardening. Nanocrystalline lamellae are characteristics of the powder structure. For the first time, the DSC technique was used to follow changes in the thickness distribution of lamellae in ultra-high-molecular-weight polyethylene reactor powder on its way to a precursor for orientation hardening. It was found that the percentage of thick (>15 nm) and thin (10 nm) lamellae in compacted samples and those sintered at temperatures lower than the melting temperature of PE (140°C) remains nearly the same. However, significant changes in the content of lamellae of different thicknesses were observed in the samples sintered at 145°C with subsequent cooling under different conditions. The influence of the lamellae thickness distribution in precursors on the mechanical characteristics of oriented filaments was discussed.

scholarly journals Actinobacteria challenge the paradigm: A unique protein architecture for a well-known, central metabolic complex

2021 ◽  
Vol 118 (48) ◽  
pp. e2112107118
Author(s):  
Eduardo M. Bruch ◽  
Pierre Vilela ◽  
Lu Yang ◽  
Alexandra Boyko ◽  
Norik Lexa-Sapart ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Metabolic Engineering ◽  
High Molecular Weight ◽  
Protein Oligomerization ◽  
Central Metabolism ◽  
Hollow Core ◽  
Protein Architecture ◽  
Unique Protein ◽  
Gene Coding

α-oxoacid dehydrogenase complexes are large, tripartite enzymatic machineries carrying out key reactions in central metabolism. Extremely conserved across the tree of life, they have been, so far, all considered to be structured around a high–molecular weight hollow core, consisting of up to 60 subunits of the acyltransferase component. We provide here evidence that Actinobacteria break the rule by possessing an acetyltranferase component reduced to its minimally active, trimeric unit, characterized by a unique C-terminal helix bearing an actinobacterial specific insertion that precludes larger protein oligomerization. This particular feature, together with the presence of an odhA gene coding for both the decarboxylase and the acyltransferase domains on the same polypetide, is spread over Actinobacteria and reflects the association of PDH and ODH into a single physical complex. Considering the central role of the pyruvate and 2-oxoglutarate nodes in central metabolism, our findings pave the way to both therapeutic and metabolic engineering applications.

Role of nano-fillers on tribological behaviour of ultra high molecular weight polyethylene composites

2020 ◽  
Vol 27 ◽  
pp. 2169-2173
Author(s):  
B. Suresha ◽  
B. Harshavardhan ◽  
Ashwij M. Rao ◽  
U.R. Koushik ◽  
R. Hemanth
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Tribological Behaviour ◽  
Ultra High Molecular Weight ◽  
Polyethylene Composites

Platelet adhesion by Subendothelium-Bound Factor VIII-VWF:Kinetics and Molecular Weight Dependence

1979 ◽  
Author(s):  
P. A. Bolhuis ◽  
K. S. Sakariassen ◽  
J. J. Sixma
Keyword(s):  
Molecular Weight ◽  
Platelet Adhesion ◽  
Fold Increase ◽  
Surface Concentration ◽  
Albumin Solution ◽  
Molecular Weight Dependence ◽  
High Molecular Weight Component ◽  
Von Willebrand ◽  
Kinetics Of

Platelet adhesion to human subendothelium was determined by perfusions with albumin solutions containing 51Cr-labeled, aspirin-treated platelets and washed red cells (hematocrit 40%) at 37° and a flow rate of 135 ml/min. Adherence was similar with Von Willebrand plasma instead of albumin solution and addition of purified FVIII-VWF caused adhesion similar to that from normal plasma. Incubation of subendotheliurn with FVIII-VWF resulted of binding of FVIII-VWF at the surface and in subsequent perfusions a surface concentration of, FVII-VWF/cm2 was shown to correct the platelet adhesion in albumin solutions towards normal. The kinetics of binding of FVIII-VWF and platelets to the subendothelium confirm the role of bound FVIII-VWF in adhesion. Binding of FVII-VWF occurs rapidly in the first minute of perfusion to about 4 x 10-4U/cm2 and then increases further to about 10-3 u/cm2 in 5 min. Platelet adhesion is similar for perfusates with and without FVIII-WF in the first minute; then the presence of FVIII-VWF results in a two-fold increase of adhesion at 5 min. Reduced adhesion was found with the high-molecular weight component of FVIII-VWF obtained by high iconic strength dissociation. Also, the activity of glycin precipitated FVIII-VWF (e.g. Hemofil FVIII-concentrate) is impaired, cross-electrophoresis of FVIII-VWF from cryoprecipitate and FVIII-VWF after glycin precipitation showed an increased mobility or the latter, indicating a reduced molecular siie. From these experiments we conclude tnat platelet adhesion is mediated by subendothelium-bound FVIII-WWF. The degree of adhesion may depend on the molecular weight of the FVIII-VWF.

Sign in / Sign up

Export Citation Format

Share Document