본 연구에서는 수지함침용 cross-die의 디자인이 LFT 공정을 통해 제조한 탄소섬유강화 열가소성 플라스틱의 특성에 미치는 영향을 조사하였다. 수지함침 cross-die의 형태를 달리하여 얻은 LFT 펠렛을 사용하여 사출성형공정을 통해 탄소섬유/ABS 복합재료 및 탄소섬유/PA6 복합재료를 제조하였다. 이후 제조한 복합재료의 ...
본 연구에서는 수지함침용 cross-die의 디자인이 LFT 공정을 통해 제조한 탄소섬유강화 열가소성 플라스틱의 특성에 미치는 영향을 조사하였다. 수지함침 cross-die의 형태를 달리하여 얻은 LFT 펠렛을 사용하여 사출성형공정을 통해 탄소섬유/ABS 복합재료 및 탄소섬유/PA6 복합재료를 제조하였다. 이후 제조한 복합재료의 인장특성, 굴곡특성, 충격특성 및 동역학적 열특성을 조사하고, 파단면을 관찰하여 비교하였다. T-type die는 cross-die 내에서 연속섬유 토우가 용융수지와 함침이 이루어지는 시간이 짧고 수직방향으로 만나 보강섬유의 필라멘트 사이로 용융수지가 침투되기 어렵다. 따라서 T-type die를 통해 제조된 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛은 연속섬유 필라멘트 사이에 용융수지가 효과적으로 함침되지 않고 수지가 겉으로만 코팅된 모습을 보였다. 반면에 I-type die는 cross-die 내에서 연속섬유 토우가 용융수지와 함침이 이루어지는 시간이 상대적으로 길고 수평방향으로 나아가 보강섬유의 필라멘트 사이로 용융수지가 침투되기 용이하였다. 따라서 T-type die를 사용하였을 때보다 I-type die를 사용하였을 때 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛에서의 수지함침성이 더욱 우수하였다. 또한 기존의 공정에서 토우프레그가 냉각 수조로 진입하기 전에 수지가 다소 유연한 상태에서 프리프레그를 눌러주었던 MT-type과 MI-type 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛에서도 MT-type보다 MI-type에서 수지함침이 개선되는 효과가 훨씬 우수하였다. I-type과 MI-type 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛을 사용하여 사출성형공정을 통해 제조한 탄소섬유/ABS 및 탄소섬유/PA6 복합재료가 T-type과 MT-type 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛을 사용하여 사출성형공정을 통해 제조한 탄소섬유/ABS 및 탄소섬유/PA6 복합재료보다 인장강도, 인장탄성률, 굴곡강도, 굴곡탄성률 그리고 저장탄성률에서 높은 값을 나타내었다. LFT 펠렛에서 탄소섬유에 ABS 또는 PA6 수지의 함침성이 좋을수록 사출성형된 복합재료 내에서 탄소섬유가 고분자매트릭스에 분산이 잘 이루어져 인장특성, 굴곡특성, 동역학적 열특성을 향상시켰다. 이러한 특성 향상 효과는 cross-die가 ‘modified'된 경우에 더 두드러지게 나타났다. 반면, 충격강도의 경우에는 T-type과 MT-type 탄소섬유/ABS 복합재료와 탄소섬유/PA6 복합재료가 I-type과 MI-type 탄소섬유/ABS 복합재료와 탄소섬유/PA6 복합재료에 비해 높게 나타났다. 이는 탄소섬유/ABS 복합재료와 탄소섬유/PA6 복합재료 내에 수지가 충분히 함침되지 않은 탄소섬유 주변에 보이드 또는 기공이 충격강도에 영향을 미친 것으로 해석되었다.
본 연구에서는 수지함침용 cross-die의 디자인이 LFT 공정을 통해 제조한 탄소섬유강화 열가소성 플라스틱의 특성에 미치는 영향을 조사하였다. 수지함침 cross-die의 형태를 달리하여 얻은 LFT 펠렛을 사용하여 사출성형공정을 통해 탄소섬유/ABS 복합재료 및 탄소섬유/PA6 복합재료를 제조하였다. 이후 제조한 복합재료의 인장특성, 굴곡특성, 충격특성 및 동역학적 열특성을 조사하고, 파단면을 관찰하여 비교하였다. T-type die는 cross-die 내에서 연속섬유 토우가 용융수지와 함침이 이루어지는 시간이 짧고 수직방향으로 만나 보강섬유의 필라멘트 사이로 용융수지가 침투되기 어렵다. 따라서 T-type die를 통해 제조된 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛은 연속섬유 필라멘트 사이에 용융수지가 효과적으로 함침되지 않고 수지가 겉으로만 코팅된 모습을 보였다. 반면에 I-type die는 cross-die 내에서 연속섬유 토우가 용융수지와 함침이 이루어지는 시간이 상대적으로 길고 수평방향으로 나아가 보강섬유의 필라멘트 사이로 용융수지가 침투되기 용이하였다. 따라서 T-type die를 사용하였을 때보다 I-type die를 사용하였을 때 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛에서의 수지함침성이 더욱 우수하였다. 또한 기존의 공정에서 토우프레그가 냉각 수조로 진입하기 전에 수지가 다소 유연한 상태에서 프리프레그를 눌러주었던 MT-type과 MI-type 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛에서도 MT-type보다 MI-type에서 수지함침이 개선되는 효과가 훨씬 우수하였다. I-type과 MI-type 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛을 사용하여 사출성형공정을 통해 제조한 탄소섬유/ABS 및 탄소섬유/PA6 복합재료가 T-type과 MT-type 탄소섬유/ABS 및 탄소섬유/PA6 LFT 펠렛을 사용하여 사출성형공정을 통해 제조한 탄소섬유/ABS 및 탄소섬유/PA6 복합재료보다 인장강도, 인장탄성률, 굴곡강도, 굴곡탄성률 그리고 저장탄성률에서 높은 값을 나타내었다. LFT 펠렛에서 탄소섬유에 ABS 또는 PA6 수지의 함침성이 좋을수록 사출성형된 복합재료 내에서 탄소섬유가 고분자매트릭스에 분산이 잘 이루어져 인장특성, 굴곡특성, 동역학적 열특성을 향상시켰다. 이러한 특성 향상 효과는 cross-die가 ‘modified'된 경우에 더 두드러지게 나타났다. 반면, 충격강도의 경우에는 T-type과 MT-type 탄소섬유/ABS 복합재료와 탄소섬유/PA6 복합재료가 I-type과 MI-type 탄소섬유/ABS 복합재료와 탄소섬유/PA6 복합재료에 비해 높게 나타났다. 이는 탄소섬유/ABS 복합재료와 탄소섬유/PA6 복합재료 내에 수지가 충분히 함침되지 않은 탄소섬유 주변에 보이드 또는 기공이 충격강도에 영향을 미친 것으로 해석되었다.
Carbon fiber-reinforced plastics (CFRP) have been receiving great attention as a light-weight material, due to their productivity, recyclability, and applicability to automotive parts. Long fiber thermoplastic (LFT) technology has been developed over the past decade and provided a class of high-perf...
Carbon fiber-reinforced plastics (CFRP) have been receiving great attention as a light-weight material, due to their productivity, recyclability, and applicability to automotive parts. Long fiber thermoplastic (LFT) technology has been developed over the past decade and provided a class of high-performance composite materials for semi-structural applications. When the pellets prepared by LFT process are used, the aspect ratio of the reinforcing fibers existing in the LFT composites is increased and the mechanical properties are improved as well. In the present study, T-type die was used to impregnate the running-out melted resin into the supplying fiber tow, in which continuous carbon fibers and melted resin meet vertically. The resin impregnation efficiency was improved by using I-type die, in which continuous fibers and melted resin meet horizontally in the cross-die of LFT machine, increasing the residence time of the melted resin running in the same direction with the preceding fiber tow in the cross-die. In this study, carbon fiber/acrylonitrile-butadiene-styrene (ABS) and carbon fiber/polyamide 6 (PA6) composites were fabricated by injection molding with 12 mm-long carbon fiber/ABS and carbon fiber/PA6 LFT pellets, respectively. The composites were prepared by using T-type, MT-type, I-type and MI-type dies for resin impregnation, respectively. We investigated the effect of die type for LFT process on the tensile, flexural, impact, and fracture behavior of carbon fiber/ABS and carbon fiber/PA6 composites. The carbon fiber/ABS and carbon fiber/PA6 LFT pellet prepared by using T-type die showed that melted resin was not effectively impregnated between the continuous fibers. When prepreg was flatten by load, carbon fibers that are collected were agglomerated with each other and the space where resin can penetrate disappeared. On the other hand, the carbon fiber/ABS and carbon fiber/PA6 LFT pellet prepared by using I-type die showed that melted resin was more impregnated than T-type one. MT-type, MI-type carbon fiber/ABS and carbon fiber/PA6 LFT pellets, which modified the prepreg during the resin was somewhat flexible before entering the cooling bath, were also more impregnated in MI-type than MT-type one. In the modified, the effect of improving resin impregnation by using I-type die was much better, because surface area where carbon fibers and resin meet was large, the resin could penetrate into the empty space between the carbon fibers when the towpreg was flatten by load. This effect was greater when PA6 resin was used than ABS resin, because the flowability of PA6 resin was much better. The tensile properties, flexural properties, and storage moduli of the carbon fiber/ABS and carbon fiber/PA6 composites were improved in the order of using T-type, MT-type, I-type, and MI-type LFT pellets. On the contrary, the result indicates that impact properties of the carbon fiber/ABS and carbon fiber/PA6 composites were decreased in the order of using T-type, MT-type, I-type, and MI-type LFT pellets. The result indicates that the resin impregnation by cross-die types in LFT pellets can affect the dispersion of residual fibers in composites after injection molding process, and the dispersion of residual fibers in composites greatly affects mechanical properties of composites.
Carbon fiber-reinforced plastics (CFRP) have been receiving great attention as a light-weight material, due to their productivity, recyclability, and applicability to automotive parts. Long fiber thermoplastic (LFT) technology has been developed over the past decade and provided a class of high-performance composite materials for semi-structural applications. When the pellets prepared by LFT process are used, the aspect ratio of the reinforcing fibers existing in the LFT composites is increased and the mechanical properties are improved as well. In the present study, T-type die was used to impregnate the running-out melted resin into the supplying fiber tow, in which continuous carbon fibers and melted resin meet vertically. The resin impregnation efficiency was improved by using I-type die, in which continuous fibers and melted resin meet horizontally in the cross-die of LFT machine, increasing the residence time of the melted resin running in the same direction with the preceding fiber tow in the cross-die. In this study, carbon fiber/acrylonitrile-butadiene-styrene (ABS) and carbon fiber/polyamide 6 (PA6) composites were fabricated by injection molding with 12 mm-long carbon fiber/ABS and carbon fiber/PA6 LFT pellets, respectively. The composites were prepared by using T-type, MT-type, I-type and MI-type dies for resin impregnation, respectively. We investigated the effect of die type for LFT process on the tensile, flexural, impact, and fracture behavior of carbon fiber/ABS and carbon fiber/PA6 composites. The carbon fiber/ABS and carbon fiber/PA6 LFT pellet prepared by using T-type die showed that melted resin was not effectively impregnated between the continuous fibers. When prepreg was flatten by load, carbon fibers that are collected were agglomerated with each other and the space where resin can penetrate disappeared. On the other hand, the carbon fiber/ABS and carbon fiber/PA6 LFT pellet prepared by using I-type die showed that melted resin was more impregnated than T-type one. MT-type, MI-type carbon fiber/ABS and carbon fiber/PA6 LFT pellets, which modified the prepreg during the resin was somewhat flexible before entering the cooling bath, were also more impregnated in MI-type than MT-type one. In the modified, the effect of improving resin impregnation by using I-type die was much better, because surface area where carbon fibers and resin meet was large, the resin could penetrate into the empty space between the carbon fibers when the towpreg was flatten by load. This effect was greater when PA6 resin was used than ABS resin, because the flowability of PA6 resin was much better. The tensile properties, flexural properties, and storage moduli of the carbon fiber/ABS and carbon fiber/PA6 composites were improved in the order of using T-type, MT-type, I-type, and MI-type LFT pellets. On the contrary, the result indicates that impact properties of the carbon fiber/ABS and carbon fiber/PA6 composites were decreased in the order of using T-type, MT-type, I-type, and MI-type LFT pellets. The result indicates that the resin impregnation by cross-die types in LFT pellets can affect the dispersion of residual fibers in composites after injection molding process, and the dispersion of residual fibers in composites greatly affects mechanical properties of composites.
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