Flow mark is a sort of surface defect on the composite that can arise during the filling stage of the injection molding process. The purpose of this study is to clarify a mechanism of the flow mark which appears on the surface of injection molded Polypropylene (PP) through the characterization of the surface structure. The materials used in this report are PP/rubber and PP/talc compounding, which are widely used in automobile part. The flow mark shows two different constitutions, such as a luster part and a cloud part on the surface of the injection molded PP. We have investigated the surface structure of PP/rubber and PP/talc composites by using scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDAX) and optical microscopy (OM). As a result, the cloud part contains higher contents of the rubber and talc compare to the luster part.

본 연구는 폴리프로필렌(PP) 수지의 Co 및 Mo 촉매에 의한 반응시간과 농도변화에 따른 저온열분해 액화특성을 파악하고자 회분식 반응기를 이용하여 특정 온도(425, 450, 475℃)에서의 전환율을 측정하였다. 열분해 시간은 20~80분으로 설정하였고 생성물은 산업통상자원부에서 고시한 증류성상 온도에 따라 가스, 가솔린, 등유, 경유, 중유로 분류하였다. 그리고 450℃ 반응온도에서 촉매 사용에 따른 전환율은 모든 반응시간에 있어 Mo 촉매 > Co 촉매 > 무촉매 순이었다. Co 및 Mo 촉매 농도별 PP 전환율 및 열분해 생성물 수율은 Co:Mo=50:50 혼합시 가장 우수한 것으로 나타났다.

Conductive polymer composites (CPCs) consist of a polymeric matrix and a conductive fil-er, for example, carbon black, carbon fibers,graphite or carbon nanotubes (CNTs). The criti-cal amount of the electrically conductive fillernecessary to build up a continuous conductive network, and accordingly, to make the material conductive; is referred to as the percolation threshold. From technical and economical viewpoints, it is desirable to decrease the conduc-tive-fillerpercolation-threshold as much as possible. In this study, we investigated the effect of polymer/conductive-fillerinteractions, as well as the processing and morphological devel-opment of low-percolation-threshold (Φc) conductive-polymer composites. The aim of the study was to produce conductive composites containing less multi-walled CNTs (MWCNTs) than required for pure polypropylene (PP) through two approaches: one using various mix-ing methods and the other using immiscible polymer blends. Variants of the conductive PP composite filledwith MWCNT was prepared by dry mixing, melt mixing, mechanofusion, and compression molding. The percolation threshold (Φc) of the MWCNT-PP composites was most successfully lowered using the mechanofusion process than with any other mixing method (2-5 wt%). The mechanofusion process was found to enhance formation of a perco-lation network structure, and to ensure a more uniform state of dispersion in the CPCs. The immiscible-polymer blends were prepared by melt mixing (internal mixer) poly(vinylidene fluoride) (PVD, PP/PVDF, volume ratio 1:1) filled with MWCN.

The crystallization of polypropylene (PP) particles in PP/decalin solution was conducted using the thermally induced phase separation(TIPS). During the control of particles sizes followed by the cooling of PP/decalin solution, particles were formed controllably, the concentrated PP resulted in an increase in the average diameter of PP particles. The effects of surfactants changes on particles sizes were investigated by using a field emission scanning electron microscope (FE-SEM). The PP crystals showed spherical shapes with a diameter 5∼18 μm. Additionally, as an effect of concentration of PP, the size distribution of the PP particles became broad with higher concentration of PP in the solution.

관형 알루미나 정밀여과와 이산화티타늄 광촉매 코팅 PP (polypropylene) 구의 혼성공정에서 질소 역세척 주기 (FT)와 시간(BT)의 영향을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피(VT)의 관점에서 광촉매 첨가 PES (polyethersulfone) 구를 사용한 기존 결과와 비교하였다. 일반적인 역세척 방법인 공기가 아닌 질소로 역세척을 한 이유는 공기에 포함 된 산소에 의해 수질분석에 영향을 줄 가능성을 최소화하기 위한 것이다. FT가 짧아질수록 Rf는 감소하고, J와 VT는 증가하 였다. 용존유기물의 평균 처리효율은 82.0%로 PES 구 결과의 78.0% 보다 높았다. 이러한 결과는 광촉매 코팅 PP 구가 광촉 매 첨가 PES 구 보다 효과적으로 용존유기물을 제거한다는 것을 의미한다. BT가 길어질수록 최종 Rf는 감소하고 최종 J는 증가하였지만, VT는 BT 15초에서 최대값을 보였다. 탁도의 평균 처리효율은 BT 변화에 따라 특별한 경향을 보이지 않았다. BT가 6초에서 30초로 증가함에 따라 용존유기물의 처리효율은 11.8% 증가하여, PES 구의 결과보다 다소 크게 증가하였다.

탄소 한외여과 및 광촉매 코팅 폴리프로필렌(PP) 구의 혼성수처리 공정에서 물 역세척 주기(FT)의 영향을 알아보 고, 탄소 정밀여과막 또는 알루미나 한외여과막 및 정밀여과막을 사용한 기존 결과들과 비교하여 분리막의 영향을 고찰하였다. FT 6분일 때 초기 60분까지 최소 막오염 저항을 보이고 최대 총여과부피를 얻어서, FT 6분이 초기 막오염의 억제에 가장 효 과적이고 최적 조건이다. 탁도의 처리효율은 98.6% 이상이며 FT 변화의 영향이 보이지 않았는데, 탄소 또는 알루미나 정밀여 과막을 사용한 기존 연구와 일치하는 것이다. 유기물의 처리효율은 FT 6분에서 98.2%로 최대값을 보였는데, 알루미나 정밀여 과막의 결과와 유사하다. 반면에 탄소 정밀여과막에서는 유기물의 처리효율이 비역세척(NBF)에서 최소이고 FT가 감소할수록 증가하였으나, 알루미나 한외여과막에서는 NBF에서 최대이고 FT가 감소할수록 역시 증가하였다. 따라서 유기물 처리효율에 대한 물 역세척 주기의 영향은 동일한 재질의 분리막이라도 기공 크기에 따라 다른 기작을 보인다는 것을 알 수 있었다.

고온에서 형성된 클레이 나노입자를 충진제로 하여 PP-클레이 나노컴포지트 용기를 제조하였으며, 이의 산소투과도와 휘발성 지방산화물 및 산화안정성을 서로 다른 두 온도(20 및 40oC)에서 측정하였다. 사용한 클레이 입자의 주성분은 ICP-OES를 통하여 Ca(40.733%)임을 알 수 있었으며, 나노컴포지트 내에 클레이 나노입자가 고르게 분산되어 있음을 TEM을 통해 확인하였다. 또한, FT-IR을 통하여 클레이 나노입자의 첨가가 PP의 작용기에 특별한 영향을 주지 않았다는 것을 규명하였다. 클레이 나노입자의 혼입으로 시트 내 기체분자의 확산 경로가 증가됨에 따라 모든 실험 온도에서 나노컴포지트 용기는 대조구보다 유의적으로 향상된 산소 차단효과를 나타내었다. 과산화물가, 공액이중산가 및 아니시딘가는 저장기간이 경과함에 따라 증가하는 경향을 보여주었다. 20oC에서 저장된 시료의 과산화물가, 공액이중산가 및 아니시딘가는 나노컴포지트 용기에서 대조구보다 유의적으로 낮게 측정되었다. 40oC에서 저장된 시료의 과산화물가 및 공액이중산가도 나노컴포지트 용기에서 대조구보다 유의적으로 낮게 측정되었으나, 아니시딘가는 저장 8주차에만 나노컴포지트 용기에서 대조구보다 유의적으로 높게 측정되었다. 주요 휘발성 지방산화물의 함량은 20 및 40oC에서 각각 저장 5주 및 3주차에 나노컴포지트 용기에서 대조구보다 상대적으로 낮게 나타났다. 본 연구 결과를 통하여 고분자 재료에 나노클레이 입자를 혼입함으로써 산소 차단효과를 향상시킬 수 있음을 확인하였으며, 이에 따라 초기 지방산화를 지연시킴으로써 식품의 전체적인 향미특성에 영향을 미칠 것으로 판단된다.

탄소섬유 한외여과막 및 광촉매 혼성 수처리를 위해 관형 여과막 외부와 원통형 막 모듈 내부 사이 공간에 광촉매를 충전하였다. 광촉매는 PP (polypropylene) 구에 이산화티타늄 분말을 플라즈마 화학증착 공정으로 코팅한 것이다. 휴믹산과 카올린 모사용액을 대상으로 막오염을 최소화하기 위해 10분 주기로 10초 동안 물 역세척을 시행하였다. 기존 결과와 동일하게 휴믹산을 10 mg/L부터 2 mg/L로 변화시킴에 따라, 막오염에 의한 저항 (Rf)이 감소하여 2 mg/L에서 최대 총여과부피 (VT)를 얻었다. 탁도와 휴믹산의 처리효율은 각각 97.1%와 74.2% 이상으로 휴믹산 농도의 영향을 받지 않았다. 그러나 기존 결과에서는 휴믹산의 농도가 증가할수록 휴믹산의 처리효율이 다소 증가하는 경향을 나타냈다.

탄소 한외여과막 및 광촉매 혼성 수처리를 위해 관형 여과막 외부와 원통형 막 모듈 내부 사이 공간에 광촉매를 충전하였다. 광촉매는 PP (polypropylene) 구에 이산화티타늄 분말을 플라즈마 화학증착 공정으로 코팅한 것이다. 휴믹산과 카올린 모사용액을 대상으로 막오염을 최소화하기 위해 10분 주기로 10초 동안 물 역세척을 시행하였다. 기존 결과와 동일하게 휴믹산을 10 mg/L부터 2 mg/L로 변화시킴에 따라, 막오염에 의한 저항(Rf)이 감소하여 2 mg/L에서 최대 총여과부피 (VT)를 얻었다. 탁도와 휴믹산의 처리효율은 각각 98.9%와 88.7% 이상이었다. UF 및 UF + TiO2, UF + TiO2 + UV 공정의 처리 분율 결과, 광촉매 흡착과 광산화에 의해 탁도는 거의 처리되지 않았으나, 광촉매 흡착 및 광산화에 의한 휴믹산 처리 분율은 각각 2.5%, 12.3%이었다. 기존 결과와 비교하면, 분리막의 재질과 기공의 크기에 따라 광촉매 흡착과 광산화에 의한 휴믹산의 처리 분율이 다르게 나타났다. 공정이 단순화될수록 180분 운전 후 막오염 저항(Rf,180)은 증가하였고, 최종 투과선속(J180)은 소폭 감소하였다.

Effects of ethylene-propylene diene monomer (EPDM)/polypropylene (PP), zinc oxide, stearic acid, and clay on the combustive properties based on EDPM/PP were investigated. The EDPM/PP/clay nanocomposites was compounded to prepare specimen for combustive analysis by cone calorimeter (ISO 5660-1). It was found that the specific mass loss rate (SMLR) in the nanocomposites decreased due to the fire resistance compared with unfilled EDPM/PP, while the nanocomposites showed the higher total heat release (THR), higher CO production release, and higher specific extinction area (SEA) than those of virgin EPDM/PP. The stearic acid for softening ruber increased the THR and amount of smoke by itself, combustible.

Compatibility and properties of PP/N66 blends with or without PP-g-MAH as a compatibilizer were investigated by DSC, SEM and universal testing machine. Morphological studies revealed that PP and N66 were incompatible and addition of PP-g-MAH was very effective to enhance the compatibility between PP and N66. The compatibilization effect between N66 and PP-g-MAH was based on the reaction between the amine end group of N66 and anhydride group in PP-g-MAH. The crystallization and melting behavior of PP/N66 blends were investigated and the results of analyses for enthalpy changed were discussed. The Izod impact strength could be improved by optimizing the compatibilizer concentration. Tensile strength, elongation at break, notched Izod impact strength were increased with using compatibilizer, however, both the compatibilized and the noncompatibilizer blends did not show any big difference in the flexural modulus.

In this study, by using oleic acid and polypropylene glycol, good natured antifoaming agent for suitable electronics process under the alkaline conditions were synthesized. For the synthesized mono and diesters, acid value, hydroxyl value was measured, and identified by FT-IR and 1H-NMR spectroscopy. Surface properties such as surface tension, critical micelle concentration(cmc) for diluted aqueous solution was measured, and tested the antifoaming properties according to the difference of alkyl chain length, various concentration, temperature and pH. The surface tension of synthesized antifoaming agent, PPMO(Polypropylene glycol monooleate) was 24.3 dyne/cm, PPDO(Polypropylene glycol dioleate) was 23.7 dyne/cm. By increasing of the alkyl chain length, surface tension was decreased slightly, and showed good antifoaming properties at 0.06 wt% concentration and 50℃, pH 11. These synthesized compounds are expected to apply as a suitable antifoaming agents in the semiconductor and the PCB(Printed Circuit Board) manufacturing process.

This study investigates the effect of filler content (wt%), presence of interphase and agglomerates on the effective Young's modulus of polypropylene (PP) based nanocomposites reinforced with exfoliated graphite nanoplatelets (xGnPTM) and carbon nanotubes (CNTs). The Young's modulus of the composites is determined using tensile testing based on ASTM D638. The reinforcement/polymer interphase is characterized in terms of width and mechanical properties using atomic force microscopy which is also used to investigate the presence and size of agglomerates. It is found that the interphase has an average width of ~30 nm and modulus in the range of 5 to 12 GPa. The Halpin-Tsai micromechanical model is modified to account for the effect of interphase and filler agglomerates and the model predictions for the effective modulus of the composites are compared to the experimental data. The presented results highlight the need of considering various experimentally observed filler characteristics such as agglomerate size and aspect ratio and presence and properties of interphase in the micromechanical models in order to develop better design tools to fabricate multifunctional polymer nanocomposites with engineered properties.

In this work, the effect of glycidyl methacrylate grafted multi-walled carbon nanotubes (GMA-MWCNTs) on the viscoelastic behaviors of polypropylene (PP) based nanocomposites was studied. The GMA-MWCNTs/PP was prepared using a bravender at 200℃ by melt mixing as a function of GMA-MWCNT content. The viscoelastic behaviors of GMA-MWCNTs/PP nanocomposites were measured by a rheometer. It was found that the GMA-MWCNTs were homogeneously dispersed in the PP matrix. The GMA-MWCNTs/PP nanocomposites showed higher storage modulus, loss modulus, and shear viscosity compared to pure PP nanocomposites and the maximum value was shown at 2.0 wt% GMA-MWCNTs loading. These results were probably attributed to the strong interfacial interaction between the GMA-MWCNT and the PP matrix.

A comparative analysis of the hindered amine light stabilizers (HALS) and UV abosrber (UVA) and their respective photostabilizing effect on wood plastic composites (WPCs) are reported in this study. The influence of accelerated weathering on the mechanical properties of the composites and the microscopic morphology of a degraded layer on the cross section and the surface were studied. UV absorbers were more efficient at preventing composite lightening than was UV stabilizer. The amount of whitening decreased with the increase of photostabilizers. With the addition of a UV absorber (Tinuvin360), the tensile modulus and strength of the composites increased slightly. However, the addition of a light stabilizer (Tinuvin770) and a UV absorber decreased the tensile modulus and strength of the composites. After 250 and 500 hr exposure, tensile modulus and strength of the un stabilized and stabilized composites decreased. The tensile strength of UV absorber (Chimassorb81)-stabilized composites was significantly greater than that of control and light stabilizer (Tinuvin770)- and UV absorber (Tinuvin360)-stabilized composites. UV absorber-stabilized samples showed less whitening and photodegradation than control and light stabilizer-stabilized samples.

The combustion reaction of polypropylene was investigated using a thermogravimetric technique under an air atmosphere condition at several heating rates from 10 to 50℃/min. To obtain information on the kinetic parameters, the dynamic thermogravimetric analysis curve and its derivative were analyzed by a variety of analytical methods such as Kissinger, Friedman, Freeman-Carroll, Chatterjee-Conrad, Ozawa and Coats-Redfern methods. The comparative works for the kinetic results obtained from various methods should be performed to determine the kinetic parameters, because there are tremendous differences in the calculated kinetic parameters depending upon the mathematical method taken in the analysis.

Nanocomposites with polypropylene/clay/wood flour were prepared by melt blending and injection molding. Thermal, mechanical and morphological properties were characterized. The addition of ballmilled clay, compatibilizer and wood flour significantly improved the thermal stability of the hybrids. The tensile modulus and strength of most hybrids was highly increased with the increased loading of clay, maleated polypropylene (MAPP) and wood flour (WF), compared to the PP/WF hybrids. The tensile modulus and strength of most hybrids were highly increased with the increased loading of ballmilled clay, MAPP and wood flour, compared to the hybrids with PP/WF. The transmission electron microscopy (TEM) photomicrographs illustrated the intercalated and partially exfoliated structures of the hybrids with ballmilled clay, MAPP and wood flour.

Polypropylene (PP) composites with wood flour/wax/coupling agent were manufactured by melt compounding and injection molding. The influence of wood flour(WF), wax, and coupling agent on the mechanical and thermal properties of the composites was investigated. The addition of wood flour to neat PP has the higher tensile modulus and strength compared with neat PP. The presence of wax also improved the tensile modulus. At the same loading of PP and WF, the addition of coupling agent highly decreased the tensile modulus, and increased the tensile strength. From thermogravimetric analysis (TGA), the addition of wax improved the thermal stability of the composites in the later stages of degradation. The presence of MAPP and wood flour in turn decreased thermal stabilities of composites. From differential scanning calorimetry analysis (DSC), neither the loading of wax. nor the presence of MAPP has shown significant effect on the thermal transition of composites.

As a part of enhancing the performance of wood-plastic composites (WPC), polypropylene (PP)/ nanoclay (NC)/ wood flour (WF) nanocomposites were prepared using melt blending and injection molding process to evaluate their thermal stability. Thermogravimetric analysis (TGA) was employed to investigate thermal degradation kinetics of the nanocomposites both dynamic and isothermal conditions. Dynamic scans of the TGA showed an increased thermal stability of the nanocomposites at moderate wood flour concentrations (up to 20 phr, percentage based on hundred percent resin) while it decreased with the addition of 30 phr wood flour. The activation energy (Ea) of thermal degradation of nanocomposites increased when nanoclay was added and the concentration of wood flour increased. Different equations were used to evaluate isothermal degradation kinetics using the rate of thermal degradation of the composites, expressed as weight loss (%) from their isothermal TGA curves. Degradation occurred at faster rate in the initial stages of about 60 min., and then proceeded in a gradual manner. However, nanocomposites with wood flour of 30 phr heated at 300℃ showed a drastic difference in their degradation behavior, and reached almost a complete decomposition after 40 min. of the isothermal heating. The degree of decomposition was greater at higher temperatures, and the residual weight of isothermal degradation of nanocomposites greatly varied from about 10 to 90%, depending on isothermal temperatures. The isothermal degradation of nanocomposites also increased their thermal stability with the addition of 1 phr nanoclay and of wood flour up to 20 phr. But, the degradation of PP100/NC1/MAPP3/WF30 nanocomposites with 30 phr wood flour occurs at a faster rate compared to those of the others, indicating a decrease in their thermal stability.

신선 엽채류인 시금치의 수확 후 포장, 저장유통온도별 품질보존 및 상품성에 미치는 영향을 조사하였다. 저장 중 중량의 변화에서 포장 후 저장 시는 중량감소가 거의 없었으나, 무포장은 저장기간이 길어질수록 그리고 저장온도가 높을수록 감소율이 현저하였다. 비타민 C함량은 저장 초기에 감소가 컸으며, 저장온도가 낮을수록 감소가 적었고, 비닐포장 간에는 큰 차이가 없었다. 시금치에서 Hunter's value는 저장온도가 높을수록 b값이 높아지는 경향이었다. 시금치 저장 중 외관 신선도에서 polypropylene 비닐포장 후 저온(1~3℃) 저장은 최고 34일, 상온(10~15℃) 저장은 8일까지 상품성이 유지되었으나, 무포장 상온보관은 3일 밖에 유지되지 않았다.