How to change the hardness of PE plastic bottles?

Updated: Aug 11

PE plastic bottles are widely used in packaging containers for personal care, daily chemical, industrial chemical, food and more industries. Polyethylene (PE) is one of the five synthetic resins, PE material has excellent properties: good resistance to high and low temperatures, good mechanical properties, resistant to oil, fat, dilute acids and alkalis, and most solvents. These characteristics made PE plastic bottles durable and strength.



While in practical applications, based on different purposes of use, customers will have different needs, some customers want hardness bottles, such as detergent bottles, shampoo bottles, lotion bottles. And some customers need softer bottles to control the liquid volume, such as squeeze bottles, sauce bottles, eye drops, hair applicator bottles, and some need medium soft and hard bottles. So how to adjust the hardness of PE bottles? As professional pe lotion bottle supplier, we can meet the different needs of customers in our pe lotion bottle factory.


Hardness is the ability of a material to resist the pressure of other harder objects into its surface. Plastic blending improvement method is to blend high hardness resin in low hardness resin to improve its overall hardness. Common blending resins are: PS, PMMA, ABS and MF, etc. The resins to be modified are mainly PE, PA, PTFE and PP, etc.

Below are different ways for modify the PE bottles by plastic blending improvement method.


1. PE Plastic Bottles Blending of HDPE and LDPE

Polyethylene is divided into different types: low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE) .LDPE is softer, but it is not suitable for making various hollow containers and other products because of its poor strength and air tightness, on the other hand, HDPE is harder and lacks flexibility to make soft products. The blending of two densities of polyethylene can produce soft and hard polyethylene materials, which can be adapted to a wide range of applications.


Table 1 .give the relationship between the properties and composition of two different densities of polyethylene blends.

HDPE:LDPE

​Density(g/m³)

​Crystallization Degree

Hardness Shore (D)

Melt index(g/10min)

Softening point(℃)

Tensile strength (MPa)

Elongation at break(%)

0:100

0.920

48

49~51

1.86

106.5

0.13

750

​10:90

0.923

50

53~55

3.24

109.2

0.12

400

20:80

0.926

52

52~55

5.94

109.4

0.13

275

30:70

0.929

54

53~56

10.58

110

0.14

100

40:60

0.931

55

56~57

17.06

115

0.15

75

50:50

​0.933

57

55~57

33.00

115.6

0.17

25

60:40

0.937

59

58~59

60.0

115.6

0.17

10

70:30

0.934

64

59~61

76

118.3

0.16

10

80:20

0.947

63

61~62

144

118.8

0.15

10

90:10

0.950

69

62~64

255

119.4

0.14

10

100:0

0.952

70

63~65

467

121.1

0.14

10


As can be seen from Table 1, a series of blends with intermediate properties can be obtained after blending two polyethylenes with different densities in various ratios. The variation of these polyethylene properties, such as density, crystallinity, hardness, softening point, etc., is quite regular and conforms to the linear summation values calculated according to the blending ratio of the raw materials. However, the changes in elongation at break and tensile strength are slightly special. When the ratio of blending in HDPE is less than 60:40, the elongation at break is basically unchanged, both when the ratio is 50:50, but then the tensile strength appears a great value.



2.PE Plastic Bottles Blending of PE and ethylene vinyl acetate (EVA).

Hdpe and ethylene vinyl acetate (EVA) blends have excellent flexibility, processability, better permeability and printability, and are therefore widely valued.

EVA is a random copolymer of ethylene and vinyl acetate (VAC). EVA has a certain degree of crystallinity when the vinyl acetate content is low.

EVA for blending, low crystallinity requirements, so the application of VAC content of 40% to 70% of EVA. in addition, when EVA in VAC content in the range of 10% to 20% for plastic materials, and VAC content of more than 30% is an elastic material.

EVA is often blended with other polymers, as the latter's modifier, which is due to EVA has good flexibility, toughness, stress cracking resistance and bonding properties.

PE and EVA blends can vary in a wide range of performance, which is due to the content of VAC in the EVA used, the molecular weight of EVA, the amount of blending of EVA, blend preparation and processing molding conditions and many other factors affect its performance.


3.PE Plastic Bottles Blending of PP and PE

PP and PE blends are usually blended using mechanical blending method, easy to operate, the blend composition than easy to change, so the blend performance is easy to adjust. PP and PE blend tensile strength generally decreases with the increase in PE content; PP and PE blend, toughness has improved, for example, blended with 10% to 40% high-density polyethylene (HDPE) polypropylene blend, at -20 ℃ when the ball impact The strength is more than eight times higher than that of PP, and the processing fluidity is increased, so it is suitable for injection molding of large containers.


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