• 한국기계가공학회지
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• 제3권4호
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• pp.95-100
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• 2004

Plastics is used to produce precise parts with an inclusion of a reinforcement material such as glass fiber or carbon fiber to improve the dimension accuracy. The plastic goods can be produced with inaccurate dimensions, low mechanical strength, or residual stress due to the over packing of cavity inside, if the filling balance of melt resin is not accomplished. To overcome this problem, it is necessary to design the runner system with the geometrical balance at the mold design stage. However, even if the balanced runner system is achieved, a severe filling imbalance is observed practically in a multi-cavity mold. In this study, experiments were performed with Taguchi method to achieve the filling balance in multi-cavity mold with a symmetric runner system, by the use of pure PA and PA with glass fiber 33%. The experimental results were investigated to understand the effect of related molding factors on the filling imbalance for two resins.

• 한국재료학회지
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• 제3권2호
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• pp.175-184
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• 1993

Nd-Fe-B계에 Co와 Al을 첨가한 자석합금을 진공유도용해로에서 제조하여 이들 합금을 단롤법으로 melt-spun시켜 급냉리본을 얻었다. 제작된 급냉리본의 냉각속도에 따른 자기적 성질의 변화를 조사하였고, 최적의 급냉속도에서 제작된 리본을 파쇄하여 resin bond 자석을 제조하였으며, 이들 급냉리본 및 bond자석의 자기적 성질, 미세구조, 결정구조에 관하여 연구, 조사하였다. 이들 급냉리본의 자기적 성질은 급냉속도에 따라 크게 변하였으며 20m/sec전후에서 최적의 자기적 성질을 보였다. 이때의 급냉리본의 미세조직은 Nd-rich의 입계상이 미세한 N$d_2$F$e_14$B결정립을 둘러싼 cell 형의 구조였으며, 특히 Al이 2.1at%첨가된 리본시료에서는 iHc=15.5KOe, Br=7.8KG, (BH)max=8.5MGOe의 자기적 성질을 나타내었다. 최적의 급냉속도에서 제작된 리본을 polyamide resin과 2.5wt%의 비율로 혼합하여 상온에서 성형, 결합시켜 제작한 bond자석에서 보다 현저히 향상되었으며 유지시간이 8분인 경우 iHc=10.8KOe, Br=7.3KG, (BH)max=8.0MGOe의 값을 가졌다. 한편, 자구구조는 maze pattern이 주로 관찰되어 자화용이축인 C축이 배열되었으며 bond자석에서보다 hot-press 자석에서 자구폭이 보다 작았다.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.453-462
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• 2017

PURPOSE. The purpose of this study was to investigate the in vitro cytotoxicity of thermoplastic denture base resins and to identify the possible adverse effects of these resins on oral keratinocytes in response to hot water/ food intake. MATERIALS AND METHODS. Six dental thermoplastic resin materials were evaluated: three polyamide materials (Smile tone, ST; Valplast, VP; and Luciton FRS, LF), two acrylic materials (Acrytone, AT; and Acryshot, AS), and one polypropylene resin material (Unigum, UG). One heat-polymerized acrylic resin (Vertex RS, RS) was chosen for comparison. After obtaining extracts from specimens of the denture resin materials (${\phi}=10$ mm and d=2 mm) under different extraction conditions ($37^{\circ}C$ for 24 hours, $70^{\circ}C$ for 24 hours, and $121^{\circ}C$ for 1 hour), the extracts (50%) or serial dilutions (25%, 12.5%, and 6.25%) in distilled water were co-cultured for 24 hours with immortalized human oral keratinocytes (IHOKs) or mouse fibroblasts (L929s) for the cytotoxicity assay described in ISO 10993. RESULTS. Greater than 70% viability was detected under all test conditions. Significantly lower IHOK and L929 viability was detected in the 50% extract from the VP ($70^{\circ}C$) and AT ($121^{\circ}C$) samples (P<.05), but only L929 showed reduced viability in the 50% and 25% extract from LF ($37^{\circ}C$) (P<.05). CONCLUSION. Extracts obtained from six materials under different extraction conditions ($37^{\circ}C$, $70^{\circ}C$, and $121^{\circ}C$) did not exhibit severe cytotoxicity (less than 70% viability), although their potential risk to oral mucosa at high temperatures should not be ignored.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1819-1824
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• 2006

The general objective of the present study was to investigate the potential application of the UV spectroscopic method for determination of the polymeric additives present in papermaking fibrous stock solutions. The study also intended to establish the surface-chemical retention model associated with the adsorption kinetics of additives on fiber surfaces. Polyamide epichlorohydrin (PAE) wet strength resin and imidazolinium quaternary (IZQ) softening agents were selected to evaluate the analytical method. Concentrations of PAE and IZQ in solution were proportional to the UV absorption at 314 and 400 nm, respectively. The time-dependent behavior of polymeric additives obeyed a mono-molecular layer adsorption as characterized in Langmuir-type expression. The kinetic modeling for polymeric adsorption on fiber surfaces was based on a concept that polymeric adsorption on fiber surfaces has two distinguishable stages including initial dynamic adsorption phase and the final near-equilibrium state. The simulation model predicted not only the real-time additive adsorption behavior for polymeric additives at high accuracy once the kinetic parameters were determined, but showed a good agreement with the experimental data. The spectroscopic method examined on the PAE and IZQ adsorption study could potentially be considered as an effective tool for the wet-end retention control as applied to the paper industry.

• 한국안광학회지
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• 제18권4호
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• pp.365-371
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• 2013

목적: 본 연구에서는 사출형 안경테 소재로 사용되고 있는 폴리아미드-12 수지인 TR-90을 대체하기 위하여 폴리아미드-66에 유리섬유(glass fiber)를 함량별로 블렌드하여 각 조성물의 물리적, 열적 특성을 평가하여 안경테로써의 적용 가능성을 검토하였다. 방법: 유리섬유의 함량 변화에 따른 폴리아미드-66 조성물의 특성변화를 고찰하기 위해 이축압출기를 이용하여 함량별 조성물을 제조하였다. 제조된 조성물의 기계적강도, 열적 특성, 코팅성 및 절삭가공성을 평가하였다. 이를 통하여 기존 TR 안경테 제품과의 성능 비교 및 안경테로써 적용 가능성을 평가하였다. 결과: 폴리아미드-66/유리섬유 조성물의 특성 평가 결과, 유리섬유의 함량이 증가할수록 성형수축율이 감소하며, 기계적 강도가 증가하는 것으로 나타났다. 유리섬유의 함량이 0 wt%인 경우 인장강도는 $498kg/cm^2$에서 30 wt%가 함유된 경우 $849kg/cm^2$까지 증가하였다. 코팅성 평가 결과 유리섬유 5 wt%에서는 코팅강도가 4 B였고, 그 이상에서는 5 B로 매우 우수한 코팅 특성을 나타내었다. 결론: 30 wt%의 유리섬유가 블렌드된 경우 기계적 강도가 크게 향상되나 이와 더불어 경도가 상승되며, 점도가 증가하여 사출온도가 높아지며, 제품에 플로우 마크가 생기는 것으로 나타났다. 유리섬유가 블렌드된 폴리아미드-66의 도료 코팅성은 모두 우수하였다. 전반적으로 물성 및 가공성 등을 평가해볼 때, 유리섬유의 함량이 약 10 wt% 내외의 경우 안경테로써의 적용이 가능하다고 판단된다.

• Journal of Welding and Joining
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• 제16권2호
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• pp.48-56
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• 1998

This study was performed to find the best bonding conditions by comparing mechanical properties in thermoplastic resin of polyethylene (PE) and polyamide (PA) adhesion. Following results were obtained from the tests with varying welding time and welding pressure. Satisfactory adhesion was executed in ultrasonic welding for the same materials of PE and PA. The best welding conditions were found to be welding time of 1 second, welding pressure of 250kPa for PE-PE weding, 2 second and 350kPa for PA-PA welding. Welding time and welding pressure end to increase with the increase of materials strength. Dissimilar materials were adhered when adhesion and ultrasonc welding were performed simultaneously. The observation of the structure of ultrasonic welding area with microscope showed differenticated structures between well adhered region and badly adhered region.

• 접착 및 계면
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• 제3권1호
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• pp.9-12
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• 2002

In this paper, N,N-m-phenyenedimaleimide (m-PDM), Polyamide Resin (PI) and Metallic dimethacrylate etc. influencing the heat resistance of anaerobic adhesive has been studied, an anaerobic adhesive composition capable of post-cure expansion and $230^{\circ}C$ temperature resistance comprising a multifunctional methacrylate and m-PDM capable of effectuating expansion upon post-cure has been developed. A homogeneous mixture of a monomer and m-PDM are subjected to a first cure heat stage (Room Temperature) wherein a rigid partially-cured plastic is formed and a post-cure heat stage ($150^{\circ}C$) to effectuate permanent expansion of cured adhesive composition.

• Composites Research
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• 제37권3호
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• pp.186-189
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• 2024

본 연구는 나노필러가 혼합된 열가소성 탄소섬유강화 복합재료(Carbon fiber reinforced thermoplastic polymer, CFRTP)의 물성을 비교 평가하였다. Polyamide 6 (PA6) 수지에 Multi-wall carbon nano tube (MWCNT), Silicon oxide, Core shell rubber, Aramid nano fiber 등의 다양한 나노필러를 혼합한 후, 이를 기지재(Matrix)로 탄소섬유강화복합 재료(CFRP)를 제조하여 그 물성을 측정하였다. 나노필러의 종류와 혼합비율에 따라, 인장강도, 층간계면결합력 (Inter-laminar shear strength), Izod 충격 강도 등이 측정되었다. 인장 강도와 충격 강도의 경우 Core shell rubber를 혼합한 경우 가장 높은 물성을 가졌으나, 계면결합력은 silicon oxide를 1 wt.% 이하 혼합하였을 때 최적값을 가졌다.

• Korean Chemical Engineering Research
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• 제49권4호
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• pp.460-464
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• 2011

Poly(ether-block-amide)(PEBA, $PEBAX^{TM}$)는 열가소성 탄성체(thermoplastic elastomer, TCU)로서 hard-rigid amide block과 soft-flexible ether block으로 구성되어 있으며, 분자량과 두 block간의 구성비에 따라 여러 종류가 있다. $PEBAX^{TM}$는 분리막소재로 이용할 경우, $PEBAX^{TM}$의 hard amide block은 우수한 기계적 특성과 선택도를, 그리고 soft ether block은 높은 투과도를 제공할 수 있다. 따라서 본 연구에서는 2종류의 $PEBAX^{TM}$를 사용하여 기체분리막을 제조하고, 종류에 따른 이산화탄소와 메탄의 투과특성 변화를 연구하였다. 또한 순수 $PEBAX^{TM}$ 분리막의 투과특성을 향상시키기 위해 무기전구체로서 TEOS(tetraethoxysilane)를 사용하여 $PEBAX^{TM}$/TEOS 하이브리드막을 제조하고, 그 투과특성을 순수 $PEBAX^{TM}$ 분리막의 결과와 비교하였다. 순수 $PEBAX^{TM}$-1657과 $PEBAX^{TM}$-2533 분리막의 투과도 측정 결과, ether block의 비율이 상대적으로 높은 $PEBAX^{TM}$-2533 분리막의 투과도 계수가 보다 높은 투과도 계수값을 가졌다. 이는 $PEBAX^{TM}$-2533의 경우, 상대적으로 높은 ether block 함량 때문에 고분자 사슬의 유연성이 보다 크기 때문으로 볼 수 있다. $PEBAX^{TM}$/TEOS 하이브리드 분리막의 투과특성을 순수 $PEBAX^{TM}$ 분리막의 결과와 비교할 때, 하이브리드 분리막의 기체 투과도 계수가 보다 높음을 알 수 있다. 이는 TEOS의 축합반응으로 생성된 silica domain에 의해 결정성이 감소하고 또한 이산화탄소와 silanol group과의 친화도(affinity) 증가에 따른 용해도가 증가하기 때문으로 볼 수 있다. 하이브리드 분리막의 투과도 계수 증가에도 불구하고 이상분리인자는 거의 비슷하거나 약간 감소하였음을 알 수 있다. 이는 이산화탄소와 silanol group의 친화도 증가로 인한 용해선택도의 증가에 기인한 것으로 볼 수 있다.

• 대한치과기공학회지
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• 제30권2호
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• pp.47-56
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• 2008

This is a research for thickness change of denture base according to the shape of sprue & investment position of denture base in flask when injecting polyamid base resin for flexible partial denture as a part of study for Valplast among the flexible partial denture with a nylon base. It has been introduced several kinds of flexible partial denture product with a nylon base, but Valplast is the most widely used product among them. Valplast has been the most generally used material today since developed in 1950s in the United States as a material for flexible partial denture. Valplast is much more aesthetic than general metal-acrylic partial denture due to its translucent pink color and biocompatibility in terms of material characteristic. It keeps its flexibility for a long time after production, imposes a less burden on the teeth used as abutment, and it can be easily insert and remove due to its particular suppleness. Moreover, it is felt like real teeth more than metal-acrylic partial denture when being put in and takes alveolar bone under good protection since it receives occlusal force equally under the denture base. The most outstanding feature of Valplast is flexibility. The extent of its flexibility is determined by width & thickness of denture base. Considering general working procedure of Valplast, it can be seen that the thickness of denture base formed out of wax is increasing by the pressure while injecting resin. This research is to decide and test on the thickness increasing of Valplast by injecting pressure and the hypothesis upon that and is to prepare the basis estimating the increasing extent of thickness of denture base on the basis of the test result. In this test, it is expected occlusal malposition & thickness increasing of denture base by injecting pressure according to 4 kinds of test data which are to select 3 types of sprue method settling the forefront position at which the test material of fixed standard can be invested and to position the test material at the rearmost part keeping the minimum distance to set sprue. For 4 kinds of injecting test by investment position & sprue type, 20 test materials, 5 for each test were produced and a pressure of 1,180Kg was given with automatic injector of air cylinder type. The results are as follows: 1. For the amount of thickness increasing of denture base by investment position, the thickness of front investment is less increasing than the one of rear investment. 2. For the amount of thickness increasing of denture base by sprue type, the thickness of straight decompression sprue type which can absorb the injecting pressure after injecting polyamide base resin is less increasing than the other sprue types.