Scholarlink

<p>This paper investigates the temperature resistance of the load-bearing elements of bonded spruce joints subjected to static tensile shear stress immediately after thermal exposure. Four types of adhesives were used: one-component polyurethane, melamine-urea-formaldehyde, resorcinol-phenol-formaldehyde, and epoxy. The joints were exposed to temperatures of 100, 120, 140, 160, and 180&#xa0;° C for 1 and 2&#xa0;h. To evaluate the influence of temperature on potential wood degradation and its effect on the thermal resistance of bonded joints, the wood itself was subjected to the same conditions and tests as the bonded joints. To isolate the effect of the adhesives, thin films were prepared and their change in stiffness during heating up to 180&#xa0;° C was measured using dynamic mechanical analysis. None of the adhesives were fully cured, and post-curing led to an increase in storage modulus and, in the case of MUF and PRF adhesives, significant shrinkage of the films. The strength of all joints decreased with increasing temperature. A continuous decrease was observed in epoxy joints, whereas the other joints exhibited fluctuations in strength. With respect to the decrease in strength, a temperature of 100&#xa0;° C already appears to be critical due to glass transition of all adhesives. Adhesives began to show thermal degradation at 140&#xa0;° C, which led to an increased incidence of adhesive failure in the joints, however the strength of the wood was also reduced above 140&#xa0;° C (a significant drop after 2&#xa0;h). 1&#xa0;C PUR-bonded joints exhibited the highest strength at 20&#xa0;° C and after thermal exposure, but all adhesive joints except EP demonstrated considerable thermal resistance. A significant effect of the duration of temperature exposure was also demonstrated.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Temperature resistance of spruce joints bonded with four adhesives and correlation with thermal behaviour of wood and thin adhesive films

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年3月25日

查看全文
  • Jan Vaněrek,
  • Radka Bálková,
  • Adam Běťák,
  • Petra Laciková

摘要

This paper investigates the temperature resistance of the load-bearing elements of bonded spruce joints subjected to static tensile shear stress immediately after thermal exposure. Four types of adhesives were used: one-component polyurethane, melamine-urea-formaldehyde, resorcinol-phenol-formaldehyde, and epoxy. The joints were exposed to temperatures of 100, 120, 140, 160, and 180 ° C for 1 and 2 h. To evaluate the influence of temperature on potential wood degradation and its effect on the thermal resistance of bonded joints, the wood itself was subjected to the same conditions and tests as the bonded joints. To isolate the effect of the adhesives, thin films were prepared and their change in stiffness during heating up to 180 ° C was measured using dynamic mechanical analysis. None of the adhesives were fully cured, and post-curing led to an increase in storage modulus and, in the case of MUF and PRF adhesives, significant shrinkage of the films. The strength of all joints decreased with increasing temperature. A continuous decrease was observed in epoxy joints, whereas the other joints exhibited fluctuations in strength. With respect to the decrease in strength, a temperature of 100 ° C already appears to be critical due to glass transition of all adhesives. Adhesives began to show thermal degradation at 140 ° C, which led to an increased incidence of adhesive failure in the joints, however the strength of the wood was also reduced above 140 ° C (a significant drop after 2 h). 1 C PUR-bonded joints exhibited the highest strength at 20 ° C and after thermal exposure, but all adhesive joints except EP demonstrated considerable thermal resistance. A significant effect of the duration of temperature exposure was also demonstrated.