HOW MUCH YOU KNOW LLDPE FILM?
1 Heat sealability
2 Melting performance
3 Thermal performance
4 Physical and mechanical properties
Melting performance
Melting performance depends on factors such as relative molecular mass, relative molecular mass distribution, and long-chain branching. Similarly, the melt flow rate LLDPE and the relationship between LDPE and shear rate: The behavior of LLDPE is similar to HDPE with a relatively narrow molecular weight distribution, and has a higher melt viscosity than LDPE, so the extrusion load during extrusion molding increases and the calorific value Also increased.
Since the melt stress relaxation time is short and the residual stress in the injection molded product is small, the shrinkage rate is small and the warpage is also small.
Thermal performance
Physical and mechanical properties
The ratio of LLDPE's tensile properties to LDPE properties, the number of stretches and tensile yield strength is large, especially the tensile breaking strength and elongation at break. Generally, the energy required for breaking can be obtained from the area of the stress-strain curve. Use this as an indicator of resin rigidity. Obviously, the rigidity of LLDPE is good, which may be attributed to the large number of tethered molecules in the LLDPE molecule.
The relationship between rigidity and density: the lower the density, the worse the rigidity (ie, softer). In terms of the same density, the impact strength of LLDPE wants to hit, and the impact strength of C6 and C8 comonomer polymers with more than C4 is higher.
The physical and mechanical properties of LLDPE film are significantly better than LDPE, and its softness, toughness, cold resistance and puncture resistance are better than LDPE.
Physical property parameter table of LLDPE film
performance
Numerical value
Tensile strength / Mpa
25.5
Stretching rate /%
800
Shore hardness
56
Tear strength / (N / cm)
980
Vicat softening point / ℃
107
Brittleness temperature / ℃
