Discussion Effect of Different Kinds of Epoxy Resin on Mechanical Properties of Adhesives

1. Introduction

  Epoxy resin is an important thermosetting resin in China. At present, the production capacity of epoxy resin I in China has exceeded 50% of the global total production capacity. The adhesive developed with liquid epoxy resin has the advantages of good mechanical properties, high bonding strength, chemical corrosion resistance, high stability, etc. This kind of adhesive is mainly composed of epoxy resin, curing agent, accelerator, etc. It has good compatibility with most bonding substrates in life, such as metals, wood and some plastics.

 Because of its excellent comprehensive properties, epoxy adhesives have been widely used in bonding metal materials and non-metallic materials. In order to further obtain the epoxy resin adhesive with better performance, this paper focuses on changing the proportion of epoxy resin in the formula, and the epoxy resin adhesive developed by using different tree resin mixture proportions has passed various mechanical property tests, thus demonstrating the impact of epoxy resin on the mechanical properties of its adhesive.

2. Experimental

a) Experimental materials

  Bisphenol A (E-51 type) epoxy resin; Bisphenol A (E-44 type) epoxy resin; Polyphthalamide 650 # with low relative molecular weight; Silane coupling agent (KH-580); T-31 phenolic amine epoxy curing agent; Silica gas phase method.

b) Experimental Steps

  Preparation of component A: first, prepare the main resin, add fillers, accelerants and other additives in turn, and then stir continuously for 3h at room temperature, then add reinforcing agent and coupling agent in turn and stir continuously for 0.5h to prepare component A of adhesive.

  Preparation of component B: firstly, add polyphthalamide, T-31 curing agent, filler, etc. in turn, stir continuously for 3h at room temperature, then add coupling agent and reinforcing agent, and stir continuously for 0.5h to prepare component B of adhesive.

  When preparing the sample, change the content of oleoresin. The content of main epoxy resin includes 40%, 45%, 50%, 55% and 60%. The first scheme is to adjust the content of E-51 epoxy resin; The second scheme is to adjust the content of E-44 epoxy resin; The third solution is to mix E-44 resin and E-51 resin in a ratio of 2:1, and then adjust the content. The mechanical properties of adhesives with different content and different proportion were tested and analyzed.

  c) Performance Testing

  Shear strength (MPa): Determine the test method according to GB/T 7124-2008.

  Impact strength (MJ/m2): determine the test method according to GB/T 6328-1999.

  Shore A hardness: it shall be tested according to GB/T531.1-2008 hardness tester.

 3. Results and Discussion

  a) Effect of different contents of epoxy resin E-51 on its mechanical properties

  The corresponding test results of epoxy resin E-44, E-51 and E-44 mixed with E-51 at different dosage are shown in Table 1, Table 2 and Table 3.

Table 1 Test results of different dosage of epoxy resin E-51

  As shown in Table 1, with the increase of the amount of epoxy resin E-51 added to the main body, the corresponding shear properties, impact properties and Shore hardness of the developed adhesive showed a trend of increasing first and then decreasing. The shear strength and impact strength of the adhesive with 55% of epoxy resin E-51 reached the maximum, which were 21.548MPa and 2.54MJ/m2, respectively, It can be seen that the epoxy resin reacts well with the crosslinking agent coupling agent at this dosage. However, the Shore hardness reached the maximum when the amount of E-51 was 50%. It was initially speculated that the reason was related to the type and amount of curing agent used. The specific reason for this result still needs to be followed up by subsequent research. As the main resin of the adhesive, the amount of epoxy resin will inevitably affect the mechanical properties of the adhesive.

  b) Effect of different contents of epoxy resin E-44 on its mechanical properties

 Table 2 Test results of different dosage of epoxy resin E-44

  Similarly, in Table 2, there is the same rule as in Table 1. It can be clearly found that the amount of epoxy resin has a great impact on the mechanical properties of the adhesive sample. Looking at the whole table, with the increase of the amount of epoxy resin, the shear property, impact property and Shore hardness of the adhesive have been correspondingly improved. When the proportion of epoxy resin E-44 is 50%, its mechanical properties have reached the maximum, which are shear strength 22.312MPa, impact strength 2.67MJ/m2 and hardness 77.5 respectively.

  c) Effect of Different Dosage of E-44 and E-51 on Their Mechanical Properties

Table 3 Test results of different dosages of epoxy resin E-44 and E-51 mixture

  The epoxy resins E-44 and E-51 are mixed in a ratio of 2:1. The relevant test results are shown in Table 3. It can be seen from the table that the mixed resin has the most obvious effect on the shear properties, and the impact strength is also more objective. However, the impact strength has the most obvious decline trend after reaching the peak value, while its effect on the hardness is relatively small.

4. Conclusion

  In this paper, the mechanical properties were analyzed by the method of control variables, and the test was carried out by changing the type and addition amount of tree tallow. According to the above data chart, the mixed proportion of the main epoxy resin E44 and E51 has the greatest impact on the mechanical properties of the adhesive. When the amount of resin is 55%, the shear properties, impact properties and Shore hardness of the adhesive reach the maximum, and can be achieved in actual production and meet the use needs.