Properties and application of the hottest copolyes

Performance and application of copolyester (PETG)

1 preface

there are many kinds of polyester. Pet (polyethylene terephthalate), PBT (polybutylene terephthalate) and PTT (polypropylene terephthalate) are familiar to everyone. In the 1980s, Eastman kodark company of the United States developed a new variety of polyester - PCT (poly (terephthalic acid-1,4-cyclohexanedimethanol), which is formed by PTA (terephthalic acid) or DMT (dimethyl terephthalate) and CHDM (1,4-cyclohexanedimethanol) through esterification or transesterification reaction, and then polycondensation reaction. It is a semi crystalline thermoplastic polyester. Its outstanding advantage is good heat resistance. Its melting point, glass transition temperature and thermal deformation temperature are higher than other thermoplastic polyester and engineering plastics. Therefore, it is mainly used in high temperature resistant materials, such as heat-resistant food containers, dinner plates, etc

at present, PCT can be divided into three types: filling type, copolyester type and melt blending type. The so-called copolyester type refers to the copolycondensation polymer formed by adding the monomer of the third binary ester (dibasic acid or diol) other than DMT (or PTA) and CHDM before transesterification (or esterification) and polycondensation, and alcohol modified PCT is called PETG. The crystallinity of this copolyester is greatly reduced due to the destruction of the integrity of the chain. Even when the eg/chdm ratio reaches a certain value, a completely amorphous copolyester can be obtained

the common comonomer of PETG is 1,4-cyclohexanedimethanol (CHDM), which is fully known as polyethylene terephthalate-1,4-cyclohexanedimethanol ester. It is the product of ester exchange polycondensation of terephthalic acid (TPA), ethylene glycol (eg) and 1,4-cyclohexanedimethanol (CHDM). Compared with pet, it has more 1,4-cyclohexanedimethanol comonomer and more ethylene glycol comonomer than PCT. Therefore, the performance of PETG is very different from pet and PCT. PETG is an amorphous copolyester. With the increase of CHDM in the copolymer, the melting point decreases, the glass transition temperature increases, and the crystallinity decreases, and finally an amorphous polymer is formed. Generally, the content of CHDM in PETG is 30% - 40%. PETG products have high transparency and gloss, which is a new transparent engineering plastic; In addition, it has excellent impact strength, good heat resistance, good heat sealing, no whitening in bending, scratch resistance, resistance to sample separation, anti-aging, anti-static, excellent chemical resistance, low extraction, hydrolytic resistance, good fluidity, strong coloring power, easy molding and processing, good hygiene (in line with FDA), and belongs to a new generation of environmental protection plastics

at present, the main producers of PETG are Eastman Chemical Company of the United States and SK Chemical Co., Ltd. of South Korea. China's Shantou Free Trade Zone Jinyuan polyester Co., Ltd. has also opened China's first PETG sheet production line

2 Properties of copolyester

2.1 mechanical properties

PETG copolyester has high toughness. As a sheet, pipe and packaging container, its performance is second only to polycarbonate. Table 1 shows the performance comparison of several products of Eastman

Table 1 performance comparison of Eastman PETG

performance

Test Method

Z6002

z6004

z6006

z6008

general performance

relative density

D792

1.2

1.19

1.2

1.23

molding shrinkage,%

d955

0 6

0.. 6

0.. 6

0.. 5

melt index, G cannot destroy the scraped specimen/10min (230 ℃)

/

15

22.5

15

/

(275 ℃)

/

/

/

/

intrinsic viscosity

0.72

0.62

0.72

0.73

mechanical properties

tensile strength, mpa

d638

69

71

67

65

elongation at break, %

d638

300

300

310

330

flexural modulus, mpa

d790

2.9 × 103

2.9 × 103

2.7 × 103

2.6 × 103

flexural yield strength, MPA

D790

100

100

97

96

Rockwell hardness

d785

103

107

105

105

Izod impact strength, kj/m2 (23 ℃)

D256

1.5

1.5

7

NB

(-40 ℃)

0.7

0.8

1.1

1.2

thermal performance

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