Solid phase
Official name
Poly(ethylene)
Secondary names
polyethylene; polyethene; poly(methylene); PE; PM; UHMWPE; HMWPE; PE-WAX; ULMWPE; HDPE; HDXLPE; XLPE; PEX; MDPE; LLDPE; LDPE; VLDPE
CAS number
9002-88-4
Type
Family
molecular solid
Class
non polar molecular solid
Compound type
homopolymer
Comments
The polymer has up to 7 500 000 monomers units and different branching degrees. It is classified according to its density and branching: very-low-density polyethylene (VLDPE), low-density polyethylene (LDPE), Linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), Cross-linked polyethylene (PEX or XLPE), High-density cross-linked polyethylene (HDXLPE), high-density polyethylene (HDPE), Ultra-low-molecular-weight polyethylene (ULMWPE or PE-WAX), High-molecular-weight polyethylene (HMWPE), and ultra-high-molecular-weight polyethylene (UHMWPE)
Terminal function
$CH_3$
Monomer number
n, up to 7500000
Molar mass
28.053 per mer unit $g/mol$
Polymolecularity index
1
Chemical composition
Formula
$CH_3-(CH_2-CH_2)_n-CH_3$
Chemical formula
(C2H4)n(CH3)2
Elemental formula
(C)4-n (H)10-n
Isotope mixture type
terrestrial abundance
None
  Formula Name Family Number min-max Mole fraction Isotope mole fraction State Relevance
$\bullet[C_2H_4]\bullet$ Ethylene mer molecule 1 - n 1 constituent mer main
$C$ Carbon element 2 1 constituent element main
$H$ Hydrogen element 6 1 constituent element main
Composition comments
The formula is n repeting units + 2 $-CH_3$ terminal functions
Chemical functions
  Function Number
$R-CH_2-R$ 2
Chemical bonds
  Bond Number
$\geq C-C \leq$ n
$\geq C-H$ 6
$\geq C-C \leq$ 1
$\geq C-H$ 4
Class
molecular solids with apolar molecules (01)
Type
with polyatomic organic apolar molecules (CnHm...) (01.06)
Phase name
various
Phase type
various
Polytypes
  • Very-low-density polyethylene (VLDPE) (VLDPE is defined by a density range of 0.880–0.915 g/cm3. VLDPE is a substantially linear polymer with high levels of short-chain branches.)
  • Low-density polyethylene (LDPE) (LDPE is defined by a density range of 0.910–0.940 g/cm3. LDPE has a high degree of short- and long-chain branching.)
  • Linear low-density polyethylene (LLDPE) (LLDPE is defined by a density range of 0.915–0.925 g/cm3. LLDPE is a substantially linear polymer with significant numbers of short branches.)
  • Medium-density polyethylene (MDPE) (MDPE is defined by a density range of 0.926–0.940 g/cm3.)
  • Cross-linked polyethylene (PEX or XLPE) (PEX is a medium- to high-density polyethylene containing cross-link bonds)
  • High-density cross-linked polyethylene (HDXLPE)
  • High-density polyethylene (HDPE) (HDPE has a low degree of branching and is defined by a density of greater or equal to 0.941 g/cm3.)
  • Ultra-low-molecular-weight polyethylene (ULMWPE or PE-WAX)
  • High-molecular-weight polyethylene (HMWPE)
  • Ultra-high-molecular-weight polyethylene (UHMWPE) (molecular weight numbering between 3.5 and 7.5 million amu)
Molar mass
28.053 $g/mol$
Density
0.88 - 0.965 $g/cm^3$
State NTP
solid
Refringence type
unknown
Pure color
white
Diaphaneity
transparent to translucent
Luster
vitreous
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