Mr. Plastic is ready to answer all your technical plastic questions
Dynalab Corp.'s Design and Manufacturing Engineer is available to answer your plastics questions via e-mail
. Sorry, phone calls can not be accepted as he is very busy managing our plastic fabrication facility.
Below are some examples of the hundreds of questions Mr. Plastic
has answered over the past years from around the world! This free
service is offered by Dynalab Corp. in addition to the extensive plastic
materials web pages already on our site.
Q. How long before standard acrylic yellows and degrades in an outdoor application (solar heating panels)?
A. Clear acrylic is naturally resistant (not impervious) to attack from
UV light. A panel should last many years before showing signs of attack
from UV rays. Just a bit of information for you...I read that acrylic
monomer is sometimes blended with other resins to retard breakdown from
UV attack; it was added to polyester greenhouse panels and that extended
their life by about 5 years.
Q. Is it possible to weld HDPE? I am about to start a design to
line a catcher chute with this material and welding would very much
simplify the design.
A. HDPE welds very nicely. In fact welding is the preferred method of joining HDPE.
Q. I was wondering how good is the chemical resistance of PC to
silicon. Also how well does PC ultrasonically weld during far field
A. Silicon(Si) is commonly used as a coating for polycarbonate to make
it scratch resistant. Since Polycarb is Amorphous with little or no
crystalline structure it should be well suited for ultrasonic welding.
Also, since it is rigid Far-Field welding should be fine.
Q. Is PETG as clear as Acrylic and can it be as thin as acrylic?
Well the application I am using it for is to stitch acrylic to leather,
I wanted to see if it can be used rather than using PVC.
Unfortunately, I am not sure of a good method to do this, and have not
been able to find anyone that has done this?
A. Yes PETG is clear and available in thinner gauges and so is
Polycarbonate. I’m sure your project is feasible, it’s simply a matter
of finding the right combination of materials and the proper equipment
to do the job.
Q. I am trying to design a small plastic part that will be used
outside. I originally wanted to use PP until I read on your website
that PP has a minimum temperature of 32°F or so. Would nylon be a
better choice for outside use? I have been told that I could also use
engineered PP but I do not even know what that is. This part needs to
be slightly flexible but not get brittle in the cold. Do you have any
A. It sounds like High Density Polyethylene (HDPE) would work well for
you. It has a better low temperature range than PP and won’t get brittle
under normal use. Also, be sure to use black material because it won’t
degrade due to UV light exposure.
Q. Please can you tell me the compatibility of acrylic and
acetyl with nucleic acids. Under high salt buffer conditions (i.e. as in
lysis solution) will these materials be likely to adsorb nucleic acid.
A. Both Acrylic and Acetal are hygroscopic plastics, meaning they will
absorb and store moisture. However, there is a lot of laboratory
equipment made from Acrylic that comes in contact with Nucleic Acid
molecules on a daily basis with no ill effects. I can’t cite a reference
for you but I believe a little web surfing by you may turn up a
compatibility table that shows Acrylic to be completely safe…and maybe
Acetal as well.
Q. I am looking to build some 1 gallon tanks which must contain
water for a period of 10 years or more and be exposed to exterior
sunlight as well. We have prototyped in acrylic but have found some
water loss over time, we believe due to the moisture permeability. Any
other plastics you might try, or materials to line the tank with?
A. The first thing that comes to mind is Polyethylene Terepthalate
(PET). This is a very common resin used in the packaging industry to
contain liquids, including those under pressure from carbonation.
Another possibility would be a barrier grade of Nylon, although you may
require a specialty UV stabilized grade.
Q. I am trying to determine which plastics are considered
"combustible." I am not sure how that would generally be measured, but I
don't think "melting" temperature is the same thing. The government
standard for a combustible solid is one that has a burn rate of
>2.2mm/second. If that's the standard, which plastics are
A. You will probably want to reference Underwriters Laboratories
flammability data for this information. “UL 94” is a classification for
flammability of plastic materials based on burning tests. The ratings
are 94V-0, 94V-1, 94V-2, 94HB, 94VTM-0, 94VTM-1, 94VTM-2, 94HF-1,
94HF-2, and 94HBF. These ratings correspond to burn rate, burn
direction, and ignition.