• 제목/요약/키워드: autohesion

검색결과 2건 처리시간 0.019초

층상점토 충전 브롬화 이소부틸-이소프렌 검 나노복합체의 점착거동 (Autohesion Behavior of Brominated-Isobutylene-Isoprene Gum Nanocomposites with Layered Clay)

  • 맨사비스마르크;김성진;이대학;김한길;오종갑;나창운
    • Elastomers and Composites
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    • 제49권1호
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    • pp.43-52
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    • 2014
  • 브롬화 이소부틸 이소프렌 (BIIR) 고무의 점착성에 미치는 나노점토(Cloisite 20A)의 영향을 조사하였다. 고무내 나노점토의 분산성은 SEM, TEM, XRD으로 분석하였다. 나노점토 충전 및 미충전 고무의 열적안정성은 TGA로 분석하였으며, 충전고무에서 열적안정성을 보였다. 또한 나노점토를 첨가하면 보강효과에 의해 고무의 강도가 증가하였다. 나노점토 첨가로 계면간 분자확산 정도는 감소할 것으로 판단되었지만, 본 연구에서 관찰된 분자확산에 의해 형성된 계면의 두께는 분자사슬간 엄킴현상을 유발하는데 충분하여 계면점착력이 증가하는 것으로 나타났다. 계면점착력 증가현상은 일정한 이상 (8 phr)의 나노점토가 첨가되었을 때 나타났다. 나노점토 첨가에 따른 표면특성의 변화를 조사하기 위해 접촉각 측정을 하였는데 큰 변화는 관찰되지 않았다.

유리질 중합체의 균열 Healing에 관한 연구 (제1보) -이론 모델링- (A study on Crack Healing of Various Glassy Polymers (part I) -theoretical modeling-)

  • 이억섭
    • 한국정밀공학회지
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    • 제3권1호
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    • pp.40-49
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    • 1986
  • Crack, craze and void are common defects which may be found in the bulk of polymeric materials such as either themoplastics or thermosets. The healing phenomena, autohesion, of these defects are known to be a intrinsic material property of various polymeric materials. However, only a few experimental and theoretical investigations on crack, void and craze healing phenomena for various polymeric materials have been reported up to date [1, 2, 3]. This may be partly due to the complications of healing processes and lacking of appropriate theoretical developments. Recently, some investigators have been urged to study the healing phenomena of various polymenic materials since the significance of the use of polymer based alloys or composites has been raised in terms of specific strength and energy saving. In the earlier published reports [1, 2, 3, 4], the crack and void healing velocity, healing toughness and some other healing mechanical and physical properties were measured experimentally and compared with predicted values by utilizing a simple model such as the reptation model under some resonable assumptions. It seems, however, that the general acceptance of the proposed modeling analyses is yet open question. The crack healing processes seem to be complicate and highly dependent on the state of virgin material in terms of mechanical and physical properties. Furthermore, it is also strongly dependent on the histories of crack, craze and void development including fracture suface morphology, the shape of void and the degree of disentanglement of fibril in the craze. The rate of crack healing may be a function of environmental factors such as healing temperature, time and pressure which gives different contact configurations between two separated surfaces. It seems to be reasonable to assume that the crack healing processes may be divided in several distinguished steps like stress relaxation with molecular chain arrangement, surface contact (wetting), inter- diffusion process and com;oete healing (to obtain the original strength). In this context, it is likely that we no longer have to accept the limitation of cumulative damage theories and fatigue life if it is probable to remove the defects such as crack, craze and void and to restore the original strength of polymers or polymer based compowites by suitable choice of healing histories and methods. In this paper, we wish to present a very simple and intuitive theoretical model for the prediction of healed fracture toughness of cracked or defective polymeric components. The central idea of this investigation, thus, may be the modeling of behavior of chain molecules under healing conditions including the effects of chain scission on the healing processes. The validity of this proposed model will be studied by making comparisons between theoretically predicted values and experimentally determined results in near future and will be reported elsewhere.

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