X hits on this document

115 views

0 shares

1 downloads

0 comments

6 / 20

Molecular Weight (melt flow)

  • Polymers is processed as viscous fluids

  • As polymer melt viscosity increases (or MFI decreases)

  • Processing becomes more difficult

  • End-use properties improve

  • Therefore a balance of end-use properties with processability is highly desirable.

Molecular Weight Distribution (MWD)

Broad MWD

  • Wider moulding window

  • Higher stiffness

  • Lower toughness

  • Greater tendency for warpage

Broad MWD

  • Wider moulding window

  • Lower stiffness

  • Higher toughness

  • Less tendency for warpage

  • Good surface finish

Xylene Solubles Low molecular weight It is not detrimental

fraction containing to properties of

certain amounts Polypropylene

of static polypropylene and so, kept at a minimum

However, this low molecular weight fraction acts as lubricant and improves processability

Ideal melt temperatures for PP resins

Melt Flow Rate

Melt

Temperature

(deg. C.)

1.0-1.5

250

1.6-2.5

240

2.6-4.0

230

4.1-6.5

220

6.6-10.5

210

10.6-17.5

200

17.6>

190

level.

6

Document info
Document views115
Page views120
Page last viewedFri Dec 09 06:06:02 UTC 2016
Pages20
Paragraphs564
Words2999

Comments