Re: Solvent for PVAc
"Roger W. Faulkner"
Sun, 08 Jun 1997 19:30:56 -0400
Phil Coveny wrote:
>
> We have been trying to do GPC's on polyvinyl acetate based
> emulsions to determine MWt. Since the ones we're looking at appear
> to be very high > 300,000, they are difficult to dissolve. We've
> stewed them for 24hrs plus in DMF and solubility is not complete.
> Has anyone any better ideas?
> Thanks, Phil
Did you dry the films prior to treating with DMF? A little water goes a
long way towards making polymers insoluble.
Maybe it's real gel you are failing to dissolve. If so, it's a fact of
life, and the best you can do is to determine the weight % gel. I would
expect an emulsion polymer like PVAc to have gel content. Gel is always
a function of how it is measured; I like to use .4 micron filters, and
measure the change in non-volatile weight % upon filtration.
--
Idleness is the Holiday of fools
Confucius
Roger Faulkner
48 Lake Avenue,
Woburn, MA 01801
rfaulkner@bigfoot.com
Re: dissolving PEO, help! please!
jaspevacek@mmm.com (John Spevacek)
Mon, 09 Jun 1997 08:13:35 -0500
takahashi yasuhiro wrote:
>
> In article <5n00jb$an1$1@cnn.ksu.ksu.edu>, scotbean@ksu.ksu.edu (Scott
> Bean) wrote:
>
> > Hello;
> >
> > I need some help dissolving polyethylene oxide. We are using (actually still
> > trying) to use PEO solutions for separating proteins via capillary
> > electrophoresis. There are a number of papers on this subject, but
> whenever we
> > try, we can't dissolve the stuff!!! The PEO we are using was purchased from
> > Aldrich and has a molecular weight of 100,000. We would like to use it a
> > concentration of 5% in TrisHepes buffers, pH 7.0 (100mM to 800 mM). We have
> > tried dissolving the PEO in the buffer and also in water to use as stock
> > solutions. We have tried heating, cooling and all sorts of combinations of
> > heating and cooling and the danged stuff won't dissolve!!
>
> You should soak PEO sample in water for one day and heat it.
PEO is insoluble in hot water. So heat the water to boiling, slowly add
the PEO and make sure it is well dispersed. Let the solution cool while
stirring. Ta da....
John
Opinions expressed herein are my own and may not represent those of my employer.
Re: Query about building with polymers
smileplas@aol.com (Smile Plas)
9 Jun 1997 13:37:32 GMT
In article <19970605034901.XAA07791@ladder02.news.aol.com>,
tjkugel@aol.com (TJKugel) writes:
>>The philosophical one is the
>>problem the industry has had since the 1930s - a problem that manifests
>>itself as 'image'.
>
>
>This has been in place since before the 1930's. A few years ago I went
to
>a lecture at a historic mansion in Connecticut; The lecturer ascribed
>plastic's poor image to its initial usage -- as an ivory replacement
>(remember the cellulose nitrate billiard ball story).
>
I don't disagrre that semi-synthetic plastics started life in the middle
of the last century as replacements for more costly natural materials, but
they weren't seen as a family of materials then because they were very
unusual. I suspect that only when people can start to see a family of
materials in many different products, does that family start to acquire an
image. Before then the individual plastics items would have been compared
either favourably or unfavourably to their traditional competitors. By the
188s successful plastics products were available that outsold their
natural competitors and were the way that most folk would have come across
them. By the turn of the century, two completely new industries were being
started that would not have been possible without thermoplastics, movies,
and sound reproduction for home use.
I based my comments, not on a retrospective analysis which is very
subjective, but on press cuttings of the time. The earliest adverse
references to plastics that I can find seem to date from 1929, if you have
earlier ones I would be most interested.
Incidentally, there has been quite a lot of Japanese work done on people
and their instinctive response to plastics - see Okamura et al,
Macromolecular Concept and Strategy for Humanity in Science, Technology
and Industry.
Colin williamson
Plastics Historical Society, London
Chemistry Job Openings
"Jacob Bresnahan"
9 Jun 1997 17:50:07 GMT
Chemists Needed
Many Openings
We are looking for Chemists in the Greater Boston Area. Job openings for
entry level, to chemists with up to 5 years of experience. Areas of
concentration include Polymers, Analytical (HPLC, IR, NMR), and synthetic
concentrations (Organic and Inorganic)
For more information please fax, mail, or email resume to the following:
Jacob J Bresnahan
Pro Source
Lab Resources
196 Bear Hill Rd
Waltham, MA 02154
Fax : (617) 890-2038
jakeb@hq.prosource.com
Chemistry Job Openings
"Jacob Bresnahan"
9 Jun 1997 17:50:02 GMT
Chemists Needed
Many Openings
We are looking for Chemists in the Greater Boston Area. Job openings for
entry level, to chemists with up to 5 years of experience. Areas of
concentration include Polymers, Analytical (HPLC, IR, NMR), and synthetic
concentrations (Organic and Inorganic)
For more information please fax, mail, or email resume to the following:
Jacob J Bresnahan
Pro Source
Lab Resources
196 Bear Hill Rd
Waltham, MA 02154
Fax : (617) 890-2038
E-Mail: jakeb@hq.prosource.com
Re: PET Vs HDPE
mjambro@ibm.net
Mon, 09 Jun 1997 18:30:54 -0700
Mr Cole wrote:
>
> I'm currently facing a problem that many manufacturers / distributors of
> janitorial products face: What material should you use for detergents?
>
> Traditionally HDPE bottles have been used for detergents and that's
> about the extent of my knowledge when it comes to plastics. Recently an
> oppotunity has arisen whereby we can buy 500-ml/1 litre and 5 litre PET
> "Jerry cans" at an extremely competitive price compared to the
> equivalent HDPE containers of the same size.As far as I can make out PET
> is widely used for drinking water bottles.
>
> Stress cracking was a problem for poorly made HDPE containers, will it
> be for PET containers? Our most popular container is a 130 gram
> (anything less and they would "crack") 5 litre Jerry can manufactured
> from HDPE, what do I need to look out for when I'm looking at PET
> containers?
>
> We fill the containers with three different grades of dishwashing
> liquid, laundry liquid, fabric softener, disinfectants, sanitisers and
> bleach (5-6% Sodium Hypochlorite). Can anybody forsee any problems with
> using PET?
>
> I would be grateful if any of the subscribers to this newsgroup were
> able to shed some light on a subject which I've found to be closely
> guarded by plastic bottle manufacturers, so much so that I wonder if
> they can answer the question?
>
> Bruce Cole
> Marketing Manager (Detergents Division)
Eastman Chemical is the largest manufacturer/supplier of polyester
bottle polymer. Their web site (www.Eastman.com) has a place to submit
technical questions for plastics as well as chemicals. You may want to
contact them with your question.
Re: how to measure thermal expansion of wax
bkociba@ix.netcom.com
Mon, 09 Jun 1997 14:41:48 -0700
Hello.
Writing is (almost Ph.D.) Keith Kociba from the P.K. Gallagher Thermal
Analysis and Calorimetry laboratories.
TMA with a dilatometer is indeed a good idea. It's not the only one,
though. The best solution to your problem as reported below will depend
mostly on the form of your sample before it melts, i.e., powder,
shavings, round pellets or oddly-shaped chunks. If hysteresis of the
sample upon repetitive melting is not a problem, then you can easily use
an accessory for the TA Instruments 943 Thermomechanical Analyzer to
measure the dilatation of the sample. The accessory consists simply of
a quartz cylinder (capped at one end) with a tightly fitting quartz
expansion probe which together act like a piston/cylinder arrangement.
Complicating factors: adhesion of the sample to the walls preventing
probe motion, and viscosity of the sample at elevated temperatures which
may result in breach of the seal between probe and cylinder wall. I
don't know if the most recent TAI TMA is the same or not.
For a list and contact information and (where available) WWW links to
almost ANY thermal analysis instrumentation manufacturer in the world,
please see my colleague's website at
http://chemistry.ohio-state.edu/~egundlach/ta/ta.htm
I will not recommend one mfr. over another. I only mention TAI b/c I'm
familiar with their dilatation ass'y.
ANOTHER APPROACH: (If you want more details, I'll be happy to e-mail
them to you.) Place sample in sample container with well known
volume. Attach graduated capillary to top of sample container. Fill
container up to first mark or so on capillary with low-volatility
liquid, e.g. mercury or high MW silicone oil. Immerse all but very top
of capillary in heatable bath (e.g. oil bath). Heat to temperatures
desired, recording column height in capillary as f(T). Repeat without
sample for baseline. LIMITATION: upper temperature limited by
volatility/thermal stability of oil bath.
Measuring expansion during melting may be tricky business. More than
likely you will have to use the sample-immersed-in-oil approach to get
the sensitivity you'll need for statistically valid results. Don't hold
me to that, however! :) Good luck!
Keith J. Kociba, B.S., M.S.
The Ohio State University Dept. of Chemisty
120 West 18th Ave, Box 153
Columbus OH 43210
614/292-3991 614/292-3010 FAX kkociba@chemistry.ohio-state.edu
John William Kietzman wrote:
>
> I am trying to determine the volumetric expansion characteristics
> of a series of waxes. I want to know how much each wax expands
> as it is heated from room temperature, through its melting point,
> up to a temperature where it is very fluid and pourable.
>
> A colleague of mine has measured room-temperature (solid) and
> elevated temperature (pourable) densities of some of the waxes,
> but we don't know how to measure the expansion in between. I'm
> mainly concerned with how to measure the expansion during melting,
> and I can't think of an easy way to do that.
>
> I've been told to look for a TMA with a dilatometer attachment.
> This is supposed to allow measurement of volumetric expansion
> from the solid phase, through the melt, all the way into the
> liquid phase. I've heard other people say that this method
> is not very repeatable (very technique dependent), recommending
> instead the use of a glass-capillary dilatometer in an oil bath.
>
> I've also had the devil's own time _finding_ somebody with a
> TMA with a dilatometer rig. I've found one at a company (for
> internal use only), and one materials testing lab that used to
> have one. Perkin-Elmer has such an attachment in their catalog,
> but there don't seem to have been many sold.
>
> Does anybody have any good ideas?
> Is there an easier way to measure expansion at the melt temp?
> Does anybody know whether a TMA with a dilatometer is a good idea?
> Does anybody know where I can find one?
>
> Thanks,
>
> John Kietzman
>
> Stanford University
> Rapid Prototyping Laboratory
>
> kietzman@leland.stanford.edu
> 415 723 0565
mass spectrometry of polymers
Jean-Francois Moulin
Tue, 10 Jun 1997 13:43:56 +0200
Hi,
I am looking for some information on polymer mass spectrometry, more
specifically I would like to get references on measurements
on Poly(ethylene oxide) (sample preparation, ionisation mechanism,
fragmentation, molecular weight distribution determination...).
Many thanks for any answer...
_______________________________________________
Jean-Francois Moulin
Laboratoire de Physico-Chimie des Polymeres
Universite de Mons Hainaut
20 Place du Parc
B-7000 Mons
tel +32-65-373349
fax +32-65-373354
Email Jean-Francois.Moulin@umh.ac.be
