scholarly journals Preparation of low-molecular-weight polyamide 6/hydrotalcite intercalated nanocomposites via insitu polymerization

2007 ◽  
Vol 1 (2) ◽  
pp. 98-103 ◽  
Author(s):  
Z. Yan-wu ◽  
J. Jun-qing
Keyword(s):  
Molecular Weight ◽  
Polyamide 6 ◽  
Low Molecular Weight ◽  
Insitu Polymerization

Preparation and Flame Resistance of Hydrotalcite/Epoxy Nanocomposites Containing Red Phosphorous

2011 ◽  
Vol 194-196 ◽  
pp. 1460-1463 ◽  
Author(s):  
Ya Tao Zhang ◽  
Yan Wu Zhang ◽  
Hao Qin Zhang ◽  
Jin Dun Liu
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
In Situ Polymerization ◽  
Polyamide 6 ◽  
Low Molecular Weight ◽  
Curing Agent ◽  
Micro Structure ◽  
Flame Resistance ◽  
Burning Method

In this study, the intercalated hydrotalcite (HT)/epoxy (EP) nanocomposites containing red phosphorous (RP) (HT-RP/EP) were prepared by in-situ polymerization. Firstly, low-molecular-weight polyamide 6 (PA6)/HT nanocomposite was prepared in the presence of organ-hydrotalcite with alanine as an initiator at 150°C. And then, PA6/HT composite and a certain amount of RP incorporated into epoxy resin in the presence of curing agent (polyamide 650) and HT-RP/EP nanocomposite was prepared successfully. Finally, the micro-structure and flame resistance were characterized by scan electron microscope (SEM) and vertical burning method, respectively. The results showed that HT was dispersed in the epoxy matrix evenly. HT-RP/EP nanocomposites showed significant flame resistance. When the content of both of HT and RP was 5%, the flame resistance achieved FV-0 level.

Polyamide 6 and high molecular weight phenol novolac blend having excellent mechanical properties in humid conditions

2018 ◽  
Vol 32 (6) ◽  
pp. 778-794 ◽  
Author(s):  
Takayuki Hirai ◽  
Kenzo Fukumori ◽  
Taiji Ikawa ◽  
Tetsuya Oda
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Glass Transition ◽  
High Molecular Weight ◽  
Room Temperature ◽  
Glassy State ◽  
Physical And Mechanical Properties ◽  
Polyamide 6 ◽  
Low Molecular Weight ◽  
Melt Mixing

Polymer blends of polyamide 6 (PA6) and phenol novolac (PN) were prepared by melt mixing. Up to 30 wt% of high molecular weight PN (HPN) or low molecular weight PN (LPN) was blended with PA6, and the physical and mechanical properties were examined. The water absorption of PA6 is inhibited by PN, and this effect is independent of the molecular weight of PN. PA6 and PN are miscible, and their blends show a single glass transition temperature ( T g) that is higher than that of PA6. HPN can enhance the T g of PA6 more efficiently than LPN because of its high T g. PA6 and the PA6/LPN blend after immersion in water had lower-than-room-temperature T gs transitioning to rubbery states. In contrast, the PA6/HPN blend after immersion in water had a higher-than-room-temperature T g. The PA6/HPN blend in water has excellent mechanical properties in its glassy state compared to those of PA6 in the dry state. Thus, the PA6/HPN blend can be used to broaden the applications of PA6, especially in humid conditions.

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Low-molecular-weight heparin in the prevention and treatment of thromboembolic disorders

1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Prevention And Treatment

Venous thromboembolism in a general hospital. An update with low molecular weight heparin prophylaxis

VASA ◽  
2007 ◽  
Vol 36 (1) ◽  
pp. 17-22
Author(s):  
Schulz ◽  
Kesselring ◽  
Seeberger ◽  
Andresen
Keyword(s):  
Molecular Weight ◽  
Pulmonary Embolism ◽  
Venous Thromboembolism ◽  
Low Molecular Weight ◽  
Trauma Patients ◽  
Vte Prophylaxis ◽  
Vein Thrombosis ◽  
Patients At Risk ◽  
Hospital Stays ◽  
Event Rates

Background: Patients admitted to hospital for surgery or acute medical illnesses have a high risk for venous thromboembolism (VTE). Today’s widespread use of low molecular weight heparins (LMWH) for VTE prophylaxis is supposed to have reduced VTE rates substantially. However, data concerning the overall effectiveness of LMWH prophylaxis is sparse. Patients and methods: We prospectively studied all patients with symptomatic and objectively confirmed VTE seen in our hospital over a three year period. Event rates in different wards were analysed and compared. VTE prophylaxis with Enoxaparin was given to all patients at risk during their hospital stay. Results: A total of 50 464 inpatients were treated during the study period. 461 examinations were carried out for symptoms suggestive of VTE and yielded 89 positive results in 85 patients. Seventy eight patients were found to have deep vein thrombosis, 7 had pulmonary embolism, and 4 had both deep venous thrombosis and pulmonary embolism. The overall in hospital VTE event rate was 0.17%. The rate decreased during the study period from 0.22 in year one to 0,16 in year two and 0.13 % in year three. It ranged highest in neurologic and trauma patients (0.32%) and lowest (0.08%) in gynecology-obstetrics. Conclusions: With a simple and strictly applied regimen of prophylaxis with LMWH the overall rate of symptomatic VTE was very low in our hospitalized patients. Beside LMWH prophylaxis, shortening hospital stays and substantial improvements in surgical and anasthesia techniques achieved during the last decades probably play an essential role in decreasing VTE rates.

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