The hottest polyolefin thermoplastic elastomer

Polyolefin thermoplastic elastomer (Part 2)

II. Structural characteristics and properties of thermoplastic ethylene propylene rubber

(I) structural characteristics

the biggest feature of the polymer chain structure of thermoplastic elastomer is that it simultaneously connects or grafts some plastic segments and rubber segments with different chemical structures. The reason why thermoplastic ethylene propylene rubber presents the processing characteristics of thermoplastic and the properties of rubber at room temperature is also because there are hard segments and soft segments in the macromolecular chain structure. The physical crosslinking of partially crystalline thermoplastic ethylene propylene rubber blended with special ethylene propylene rubber and polyolefin is formed by the strong condensation between the crystalline segment in the ethylene propylene rubber and the interface of thermoplastic polyolefin. The non crystalline long chain in ethylene propylene rubber is rubber segment. Partially vulcanized thermoplastic ethylene propylene rubber has chemical crosslinking formed by vulcanizing agent under dynamic vulcanization conditions. It is this crosslinking bond that makes partially vulcanized thermoplastic ethylene propylene rubber show the properties of vulcanized rubber. Indeed, the performance of thermoplastic ethylene propylene rubber mainly depends on the crystallinity of ethylene propylene rubber and the mixing ratio with polyolefin resin, or the vulcanization conditions. According to the mixing proportion. Thermoplastic ethylene propylene rubber can be divided into soft type and ① hard type according to the national metrological verification system

it can be seen from the microscopic image analysis of scanning electron microscope or phase contrast microscope that the thermoplastic ethylene propylene rubber is a non-uniform two-phase structure. With the different blending proportion of ethylene propylene rubber and polyolefin resin and the difference in relative viscosity between the two components, a structure can be formed in which rubber is the continuous phase, plastic is the dispersed phase, or plastic is the continuous phase, rubber is the dispersed phase, or the two continuous phases run through each other. With the change of phase morphology, the properties of thermoplastic ethylene propylene rubber also change. When the rubber is a continuous phase, the material properties are closer to vulcanized rubber; On the contrary, when plastic is a continuous phase, the material properties are closer to plastic

(II) performance

the performance of polyolefin thermoplastic elastomer based on ethylene propylene rubber depends on the type of raw materials used for blending and their dosage ratio. The performance of the final product is also affected by the processing method

1. Mechanical properties

with the different proportion of thermoplastic resin used, the hardness (Shore A) of thermoplastic elastomer can change in the range of 55 ~ 95, and the material can change from rubber properties to plastic properties. Polyolefin thermoplastic ethylene propylene rubber has high elasticity, small permanent deformation, wear resistance, tear resistance and other properties. It is a high polymer material with good comprehensive mechanical properties. Uniroyal Corporation of the United States has the largest variety of polyolefin thermoplastic elastomers, and can provide six series of thermoplastic elastomers with the trade mark of TPR. TPR 1000 and TPR 2000 series are the earliest industrialized products. Taking tpr1000 and tpr2000 series as examples, this paper briefly introduces the properties of polyolefin thermoplastic elastomers. See table. Among them, tpr1600 has large elasticity and good flexibility; TPR 1900 has the smallest elasticity and the highest hardness and strength. Tpr1700, tpr1800 and tpr2800 have the middle hardness and performance, and have the inherent characteristics of both rubber and plastic. The five basic types of TPR in the table show that with the increase of hardness, the tensile strength and permanent deformation of the compound increase. In addition, there are tpr3000, tpr4000 and tpr5000 series, all of which have special uses. For example, tpr3000 series has the characteristics of oil resistance and flame retardancy; Tpr4000 series and tpr5000 series can be used for the insulation and protective layer of flexible low-voltage cables. The trade mark of polyolefin thermoplastic elastomer of Monsanto Company in the United States is Santoprene. It is said that its ethylene propylene rubber is (2) protectability: the problem of protectability should be considered in the design of psia-05 experimental device from the beginning. It is completely vulcanized. The general type is divided into six grades according to the hardness. In addition to the general type, there are flame retardant grades and other grades for special purposes. See table for typical mechanical properties of Santoprene

2. Aging performance and temperature range

polyolefin thermoplastic elastomer can be used in a wide temperature range of -50 ~ 150 ℃. Short time intermittent use, wider temperature range. It has good flexibility and impact resistance at low temperature and excellent retention of mechanical properties at high temperature. The practical application shows that the performance retention rate of polyolefin thermoplastic elastomer based on ethylene propylene rubber is higher than that of other thermoplastic elastomers at higher temperature. Monsanto Company of the United States produces polyolefins of various brands with Santoprene as the trade name

Table typical properties of tpr1000/2000 series

trademark

performance

ASTM

test method

United Kingdom

TPR

1600

United Kingdom

TPR

1700

United Kingdom

.Tpr

1800

unitoyal

tpr

1900

unitoyal consumers have reason to believe that in the increasingly perfect service system and good With good service attitude,

TPR

2800

density, kg/m3

hardness (Shore A)

tensile strength, MPA

elongation at break,%

100% constant tensile stress, MPA

permanent deformation at break,%

permanent deformation at compression, %

d-297

d-2240

the main tax objects are: d-412

d-412

d-412

d-412

d-395-e

880

67

4.5

230

3.5

10

880