Bonding of Butyl and Nitrile Rubber by in situ Copolymer Formation

1989 ◽  
Vol 62 (2) ◽  
pp. 367-385 ◽  
Author(s):  
M. H. Chung ◽  
G. R. Hamed
Keyword(s):  
Molecular Weight ◽  
Peel Strength ◽  
Low Molecular Weight ◽  
Temperature Dependent ◽  
Wlf Equation ◽  
Test Speed ◽  
Strong Adhesion ◽  
Peel Adhesion ◽  
Dependent Failure

Abstract We summarize and conclude the following: 1. The T-peel adhesion between uncrosslinked layers of IIR and NBR is rate and temperature dependent. Failure is interfacial at low rates; bulk cohesive tearing of the rubber occurs at intermediate rates, while interfacial failure returns at high rates. 2. Adhesion data could be reduced to mastercurves with experimentally determined shift factors which were in reasonable agreement with those calculated from the universal WLF equation with a Tg=−69°C. 3. At the lowest test rates, peel specimens containing in situ-formed copolymer had lower strength than those without the copolymer. This is probably due to the easy slippage of the segments of the low-molecular-weight copolymer in this regime. 4. At intermediate rates, in situ copolymer had no effect on peel strength; specimens failed by bulk cohesive tearing of rubber, whether or not the copolymer was present. 5. At high rates, peel specimens containing the copolymer exhibited improved strengths. The behavior is consistent with previous results on the autohesion of elastomers. Interdiffused chains of relatively low molecular weight are only capable of providing strong adhesion when the test speed is sufficiently rapid.

Temperature dependent measurements on a low-molecular-weight photorefractive glass

2002 ◽  
Author(s):  
Ralf Bausinger ◽  
Andre Leopold ◽  
Stephan J. Zilker ◽  
Dietrich Haarer ◽  
Jolita Ostrauskaite ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Temperature Dependent

scholarly journals Preparation of Porous Polymers by ”in Situ Precipitation” Using Low Molecular Weight Gelators

2002 ◽  
Vol 34 (6) ◽  
pp. 474-477 ◽  
Author(s):  
Masahiro Suzuki ◽  
Yasuhiko Sakakibara ◽  
Satoshi Kobayashi ◽  
Mutsumi Kimura ◽  
Hirofusa Shirai ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Porous Polymers ◽  
Low Molecular Weight ◽  
Low Molecular Weight Gelators

Instabilities in the System NMMO/Water/Cellulose (Lyocell Process) Caused by Polonowski Type Reactions

Holzforschung ◽  
2002 ◽  
Vol 56 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Thomas Rosenau ◽  
Antje Potthast ◽  
Andreas Hofinger ◽  
Herbert Sixta ◽  
Paul Kosma
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Exchange Resin ◽  
Degradation Products ◽  
Ion Exchange Resin ◽  
Low Molecular Weight ◽  
Acid Component ◽  
Degradation Reactions ◽  
Polyglucuronic Acid

Summary Polonowski type degradation reactions are a major reason for the frequently observed instability of solutions of cellulose in N-methylmorpholine-N-oxide monohydrate (NMMO, 1). The degradation is induced by degradation products of cellulose and NMMO generated in situ in the Lyocell system. The presence of both an amine component, such as morpholine or N-methylmorpholine, and an acid component is required for the decomposition process to proceed. The latter might be a low-molecular-weight compound, such as formic acid, acetic acid or gluconic acid, or also a high-molecular-weight acid, such as polyglucuronic acid or ion exchange resin.

Possible Mechanisms for the Increase in Alkaline Phosphatase Activity of Lyophilized Control Material

1972 ◽  
Vol 18 (12) ◽  
pp. 1518-1523 ◽  
Author(s):  
Alistair F Smith ◽  
Barbara A Fogg
Keyword(s):  
Molecular Weight ◽  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Gel Filtration ◽  
Low Molecular Weight ◽  
Temperature Dependent ◽  
Control Material ◽  
Rate Of Increase ◽  
Control Procedures

Abstract The increased alkaline phosphatase (EC 3.1.3.1) activity of reconstituted lyophilized control sera has recently been the focus of considerable interest because of its possible implications for quality-control procedures. We confirm that these reconstituted materials show a temperature-dependent increase in alkaline phosphatase activity, but could show no alteration in activity of fresh sera. The rate of increase in activity was unaffected by dialysis of the reconstituted material, and occurred more rapidly in dilute solutions. Studies with acrylamide gel electrophoresis and Sephadex G-200 gel filtration showed that, immediately after reconstitution, a high-molecular-weight alkaline phosphatase component predominated; during subsequent spontaneous activation this component decreased, and there was a concomitant increase in a low-molecular-weight alkaline phosphatase component. The results obtained when the reconstituted material was extracted with butanol suggest that the observed changes in alkaline phosphatase activity may be attributed to the breakdown of a complex between alkaline phosphatase and lipoprotein.

scholarly journals A simple method for the production of low molecular weight hyaluronan by in situ degradation in fermentation broth

e-Polymers ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 477-481
Author(s):  
Jianfeng Mei ◽  
Zhihong Dong ◽  
Yu Yi ◽  
Yanlu Zhang ◽  
Guoqing Ying
Keyword(s):  
Molecular Weight ◽  
Enzymatic Degradation ◽  
Fermentation Broth ◽  
Low Molecular Weight ◽  
Streptococcus Zooepidemicus ◽  
Medium Ph ◽  
Simple Method ◽  
Suitable Temperature ◽  
In Situ Degradation

AbstractFermentation of hyaluronan (HA) by Streptococcus zooepidemicus was carried out in a 10-L fermentor. When the medium pH was controlled at 7.0 and the temperature was maintained at 38°C for 12 h followed by 35°C for 8 h, the yield of HA was 4.83 g/L with a molecular weight of 1,890 kDa. After the cells were removed by centrifugation from the fermentation broth, HA was slowly degraded to low molecular weight HA by hyaluronidase at a suitable temperature without a decrease in HA concentration. If the time and temperature for enzymatic degradation were controlled, the desired low molecular weight HA could be obtained by in situ degradation in the fermentation broth. The method does not require the addition of exogenous hyaluronidase, and is a simple way to produce low molecular weight HA.

scholarly journals Multi Self-Healable UV Shielding Polyurethane/CeO2 Protective Coating: The Effect of Low-Molecular-Weight Polyols

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1947
Author(s):  
Mohammad Mizanur Rahman ◽  
Rami Suleiman ◽  
Md. Hasan Zahir ◽  
Aasif Helal ◽  
A. Madhan Kumar ◽  
...  
Keyword(s):  
Molecular Weight ◽  
In Situ Polymerization ◽  
Outdoor Exposure ◽  
Low Molecular Weight ◽  
Self Healing ◽  
Polydimethyl Siloxane ◽  
Molecular Weights ◽  
Uv Shielding ◽  
Ceo2 Coating

We prepared a series of polyurethane (PU) coatings with defined contents using poly(tetramethylene oxide)glycol (PTMG) with two different molecular weights (i.e., Mn = 2000 and 650), as well as polydimethyl siloxane (PDMS) with a molecular weight of Mn 550. For every coating, maximum adhesive strength and excellent self-healing character (three times) were found using 6.775 mol% mixed with low-molecular-weight-based polyols (PU-11-3-3). Defined 1.0 wt% CeO2 was also used for the PU-11-3-3 coating (i.e., PU-11-3-3-CeO2) to obtain UV shielding properties. Both the in situ polymerization and blending processes were separately applied during the preparation of the PU-11-3-3-CeO2 coating dispersion. The in situ polymerization-based coating (i.e., PU-11-3-3-CeO2-P) showed similar self-healing properties. The PU-11-3-3-CeO2-P coating also showed excellent UV shielding in real outdoor exposure conditions.

In situ formation of AuNPs using fatty N-acylamino hydrazide organogelators as templates

2019 ◽  
Vol 43 (1) ◽  
pp. 295-303 ◽  
Author(s):  
Renata Ongaratto ◽  
Naiane Conte ◽  
Caroline R. Montes D’Oca ◽  
Rafael C. Brinkerhoff ◽  
Caroline Pires Ruas ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gold Nanoparticles ◽  
Low Molecular Weight ◽  
In Situ Formation ◽  
First Time

This work reports, for the first time, the synthesis of new fatty N-acylamino hydrazides and demonstrates the activity of these compounds as low-molecular-weight organic gelators and templates for preparation of gold nanoparticles (AuNPs).

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