Re: RE- Re: Polyethylene

Subject:      Re: RE- Re: Polyethylene
       Date:  Sun, 08 Jun 1997 12:10:00 GMT
       From:  robert.michaels-at-online.sme-dot-org (Robert Michaels)
Organization: Society of Manufacturing Engineers
         To:  tesla-at-pupman-dot-com

        Polyethylene cannot be melted in air:  It burns (starts to
        char, actually) before it reaches its melting point.

                This is a generalized rule of thumb.  Some
                of the very low molecular-weight polyethylenes
                do melt at a low enough temperature - i.e.
                before combustion.

        The melting (and for that matter, welding) of polyethylene
        is done under a nitrogen atmosphere or blanket for this

        In any event, as with all polymeric substances, polyethylene
        does not have a discrete melting point:  It just becomes
        softer and softer and softer, passing eventually into a
        formless goo.

                                 - - - - - -

        If one were intent upon making one's own polyethylene film
        at home in one's spare time (about as sensible as making
        one's own 100-w lightbulbs - IMHO):

        Obtain some low-molecular weight  =emulsifiable=
        polyethylene.  Such is usually sold in the form of pellets.
        Emulsify this is a proper mixture of surfactants and water
        (consult mfg'rs. technical service dept. for starting-point
        formulations).  Spread the emulsion out on a glass plate
        in a thin layer (special hand tools are available for
        spreading films in any desired thickness).  Allow to dry
        (oven may be used, or not), and peel the film from the

        Then go have your head examined.

                                       Polymath-icly, but not poly-
                                       anna, in -- Detroit, USA

                                       Robert Michaels

T><robert.michaels-at-online.sme-dot-org> wrote;

T>>         There's polyethylene and then there's polyethylene.  You
T>>         have to be  =really=  careful when you go out to buy
T>>         plastics of any kind these days, but especially
T>>         of any type  (more careful than going out on a Saturday
T>>         night without condoms!)...

T>Robert your comments on the cautionary use of 'new' polyethylene was
T>very good and I liked your metaphors! My oldest boy, reading over my
T>shoulder just said "Da I know what he met her for"! I just, lightly,
T>smacked him upside his head too! It may seem odd to ask this question
T>in the shadow of that post, but has anyone tried melting polyethylene
T>like from say empty milk jugs and pouring it into thin sheets of say
T>0.1 inches thick of what ever length and width would be appropriate
T>for their conductor plate size?