Polymer(Korea), Vol.18, No.4, 481-491, July, 1994
천연고무 접착에 대한 용제의 영향
Effects of Solvents on Adhesion of Natural Rubber
초록
천연고무에 가교제인 dicumyl peroxide를 혼합하여 가볍게 가교시킨 얇은 rubber sheet간의 접착강도를 180°peel test를 이용하여 측정하였다. 접착계면에 용제를 적용하여 접착력 향상에 대한 용제의 기여도를 평가하였으며, 본 실험에 적용된 용제는 benzene, toluene, n-decane, n-hexane, acetone, carbon tetrachloride, dichloromethane, cyclohexane, 그리고 공업용제이었다. 가교점간 분자량(Mc)이 5.O×103g/mole보다 작은 경우에는 접착강도(Ga)가 5.0 J/㎡ 정도 였으나, Mc가 1.0×104g/mole보다 큰 경우에는 Ga는 급격하게 상승되었다. 접촉계면에 용제를 적용했을 때, 천연고무-용제간 interaction parameter(χ)가 0.5보다 작은 경우에는 χ값이 낮을수록 접착강도는 향상되었으나 0.5보다 큰 경우에는 접착형성이 오히려 저해되었다. 천연고무 혼합물에 점착부여제인 octyl phenolformaldehyde resin(OPFR)을 첨가한 경우, 가교속도와 가교도는 감소하였으며 접착강도는 OPFR를 함유하지 않은 경우에 비하여 크게 상승되었다. 접착력 형성에 있어서 하중의 영향을 평가하였다. 접착계면에 가한 하중이 증가할수록 접착력이 증가하였으며 접촉계면에 용제를 적용한 경우에는 하중의 영향이 보다 현저하였다. 공업용제를 적용한 경우에도 다른 순수용제와 비교할 때 같은 χ값에서 접착력 향상에 비교적 비슷한 수준의 기여도를 보여 주었다.
The adhesive strength between thin sheets of natural rubber(NR), lightly crosslinked with dicumyl peroxide, was measured using a 180° peel test. Effects of solvents on adhesion were evaluated by applying the solvents at the interfacial contact. The solvents included : benzene, toluene, n-decants, n-hexane, acetone, carbon tetrachloride, dichloromethane, cyclohexane, and an industrial solvent. When the molecular weight between crosslinks(Mc) was less than 5.0×103g/mole, the work of separation(Ga) was approximately 5.0 J/㎡. However, Ga increased rapidly when Mcwas above 1.0×104 g/mole. Applyins the solvent to the contact interface, the adhesive strength was improved when the NR solvent interaction parameter(χ) was smaller than 0.5. On the other hand, adhesion was inhibited by the solvent when χ>0.5. Mixing NR compounds with octyl phenolformaldehyde resin(OPFR), a tackifier, resulted in the decrease of both the cure rate and the degree of crosslinking. The adhesive strength, as a result, was markedly increased compared with the NR compounds without OPFR. Effects of a compressive stress applied during bonding on the resulting adhesive strength were also evaluated. Adhesive strength increased as stress increased. Furthermore, the effect of pressure was intensified by the application of solvents to the contact interface. The industrial solvent contributed to the improvement of the adhesive strength at a similar level for the same value of χ when compared with the contributions of other pure solvents.
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