PlasticWork

Plastics:

Plastic #1: Polyethylene Terephthalate (PET)
Plastic #2: High Density Polyethylene (HDPE)
Plastic #3: Polyvinyl Chloride (PVC)
Plastic #4: Low Density Polyethylene (LDPE)
Plastic #5: Polypropylene (PP)
Plastic #6: Polystyrene (PS)
Plastic #7: Other.
http://www.babygreenthumb.com/p-122-safe-plastic-numbers-guide.aspx
1 pet water bottles not very safe
2,4,5 safe

Type 2 [HDPE]

 I love it since it is the safest the easiest to recycle 

  Milk jugs and Detergent bottles are made from this.

Things To Know: 

It is safe to refill HDPE containers or water bottles as it does not leach anything. 

 HDPE is a very STURDY plastic and does not melt unless under VERY extreme heat. 

  Sadly this means it lacks flexibility but it is very good for support needed in projects.

Conclusion: 

You can use this plastic with out any concern. But it does not really melt.

------------------------------------------------------------------------------

TYPE 4 [LDPE]

 another safe plastic. commonly used in the craft world 

   buttons ,Plastic Wrap, Grocery Bags, and certain food containers.

Things To Know: 

  LDPE is strong but significantly less sturdy than HDPE when in a solid form. 

  It still takes a lot to melt it [about 194F]

Conclusion: 

  LDPE is pretty safe to use. If in a solid form it takes a lot of heat to melt. 

   Use caution while trying to burn loser LDPE products such as bags, because they do catch on fire.

----------------------------------

TYPE 5 [PP]

PP is pretty safe, and is used for many things like 

  bottle caps [and tic-tac caps], Storage Bins, and Plastic dishware. 

   It does not melt easily, but it does heat up very quickly, 

     so use caution if you ever heat up a PP plastic.

Advised Caution: 

PP is quite safe, however studies have found that certain PP's may leach a biocide. 

  So use PP with caution.

Some melt down #1 but it is not very safe

  (20Min @ 350F)

melt HDPE plastic bags in a pan on the stove,
 and mold into a wheel for a robot.

HDPE melts at 265 F (often a bit lower),
  while PP doesn't melt until 320 F.
   But the plastic chips you were using might not have been polypropylene.
    If they were one of the "thermosetting" polymers, they wouldn't ever melt at all,
     just like you can never melt a hard-boiled egg.


Any of the plastics with recycling triangle numbers from 1 through 6 are "thermoplastic" polymers;
 and can (at least in theory) be melted, molded, cooled, remelted, etc. indefinitely,
  like a ice cube


HDPE (#2) and LDPE (#4) have the lowest melting points
 and emit little or nothing in the way of fumes.
   And since they are both the same polymer (polyethylene), they can be melted together!!!!

PP (#5) melts at 320 F,
 but may sometime have additives that emit harmful fumes.

PET or PETE (#1) has little or nothing in the way of fumes,
  but doesn't melt until 500 F.

PS (#6) melts at 465 F,
  but may often have additives
    that produce fumes that are much better avoided.

PVC or V (#3) melts around 220-265 F,
 but always produces very nasty, harmful, dangerous fumes.
   Don't try this at home, kids. DANGER, WILL ROBINSON! AVOID AVOID AVOID.



#1 PET gets soft and stretchy at relatively low temperatures, less than 100C. I've had success re-shaping PET bottles by carefully heating with a hot-air gun, and re-forming. Your description sounds like you want to cast (pour into a mold) rather than form (force against a mold), but forming is a lot easier.


PVC in the form of pipe doesn't get workable in larger thicknesses until 400F
  and at 500F it will reluctantly take impression from screw heads.
   however, it will only soften, its liquefication point is higher than the combustion point,
     so for higher temps it requires an oxygenless environment

---------------
#1 PET gets soft and stretchy at relatively temps < 212

I've had success re-shaping PET bottles by carefully heating
   with a hot-air gun, and re-forming.
 Your description sounds like you want to cast (pour into a mold)
   rather than form (force against a mold),
    but forming is a lot easier.

PVC in the form of pipe doesn't get workable in larger thicknesses until 400F and
 at 500F it will reluctantly take impression from screw heads.
  however, it will only soften, its liquefication point is higher than the combustion point,
  so for higher temps it requires an oxygenless environment

Make 3d printer ink

https://www.filabot.com/