• Journal of the Korean Wood Science and Technology
• /
• 제47권4호
• /
• pp.472-485
• /
• 2019

When wood plastic composites (WPCs) have been used for a certain period of time, they become waste materials and should be recycled to reduce their environmental impact. Waste WPCs can be transformed into reinforced composites, in which fillers are used to improve their performance. In this study, recycled WPCs were prepared using different proportions of waste WPCs, nanoclay, and glass fiber. The effects of nanoclay and glass fiber on the microstructural, mechanical, thermal, and water absorption properties of the recycled WPCs were investigated. X-ray diffraction showed that the nanoclay intercalates in the WPCs. Additionally, scanning electron micrographs revealed that the glass fiber is adequately dispersed. According to the analysis of mechanical properties, the simultaneous incorporation of nanoclay and glass fiber improved both tensile and flexural strengths. However, as the amount of fillers increases, their dispersion becomes limited and the tensile and flexural modulus were not further improved. The synergistic effect of nanoclay and glass fiber in recycled WPCs enhanced the thermal stability and crystallinity ($X_c$). Also, the presence of nanoclay improved the water absorption properties. The results suggested that recycled WPCs reinforced with nanoclay and glass fiber improved the deteriorated performance, showing the potential of recycled waste WPCs.

• 한국가구학회지
• /
• 제26권4호
• /
• pp.428-434
• /
• 2015

In this study, we received each wood plastic composites (WPC) from three manufacturers. These WPCs were evaluated regarding their physical and mechanical properties of both before and after accelerated weathering by ultraviolet (UV) irradiation. The total time of exposure of the WPCs to UV irradiation was 1800 h. The water absorption, volumetric swelling and shrinkage of WPCs did not affected by UV irradiation. Among the mechanical properties, there was no significant differences in bending strength and screw withdrawal resistance of UV treated WPCs compared with those of reference WPCs. However, surface hardness of WPCs showed decrease under UV irradiation. Stereoscopic microscopy observation revealed deterioration of the surface layer polymer in all weathered WPCs by UV. Exposure of the WPCs to UV irradiation caused decomposition and disappearance of the polymer layer. From this result, we can estimate that damage of polymer by UV led to a decrease in the surface hardness of the WPCs. The wood flours retained original shape after accelerated weathering by UV irradiation.

• Journal of the Korean Wood Science and Technology
• /
• 제42권5호
• /
• pp.499-509
• /
• 2014

Wood filler is a porous and anisotropic material having different size, shape, and aspect ratio. The use of wood fillers such as wood particle, wood flour, and wood pulp in wood plastic composites (WPCs) are growing rapidly because these wood fillers give improved strength and stiffness to WPCs. However, the wood fillers have originally poor compatibility with plastic matrix affecting the mechanical properties of WPCs. Therefore, to improve compatibility between wood and plastic, numbers of physical and chemical treatments were investigated. While the various treatments led to improved performances in WPC industries using petroleum-based plastics, full biodegradation is still issues due to increased environmental concerns. Hence, bio-based plastics such as polylactide and polyhydroxybutyrate having biodegradable characteristics are being applied to WPCs, but relatively expensive prices of existing bio-based plastics prevent further uses. As conventional processing methods, extrusion, injection, and compression moldings have been used in WPC industries, but to apply WPCs to engineered or structural places, new processing methods should be developed. As one system, co-extrusion technique was introduced to WPCs and the co-extruded WPCs having core-shell structures make the extended applications of WPCs possible.

• 한국가구학회지
• /
• 제24권4호
• /
• pp.379-388
• /
• 2013

In this study, the effect of various glass fiber (GF) contents in a shell layer and shell thickness changes on the flexural property of coextruded wood plastic composites (WPCs) in combination with three core systems (weak, moderate, and strong) was investigated. GF behaved as an effective reinforcement for the whole coextruded WPCs and GF alignments in the shell layer played an important role in determining the flexural property of the coextruded WPCs. At a given shell thickness, the flexural property of the whole coextruded WPCs was improved with the increase of GF content in shell. For core quality, when the core is weak, increase of GF content in shell led to improved flexural property of the whole composites and increase of shell thickness helped it. On the other hand, when the core is strong, the flexural property of the whole composites showed reduced features at low GF content in shell and increase of shell thickness aggravated it. This approach provides a method for optimizing performance of the coextruded WPCs with various combinations of core-shell structure and properties.

• Animal Bioscience
• /
• 제34권1호
• /
• pp.36-47
• /
• 2021

Objective: This study determined the optimal ratio of whole plant corn silage (WPCS) to corn stover (stems+leaves) silage (CSS) (WPCS:CSS) to reach the greatest profit of dairy farmers and evaluated its consequences with corn available for other purposes, enteric methane production and milk nitrogen efficiency (MNE) at varying milk production levels. Methods: An optimization model was developed. Chemical composition, rumen undegradable protein and metabolizable energy (ME) of WPCS and CSS from 4 cultivars were determined to provide data for the model. Results: At production levels of 0, 10, 20, and 30 kg milk/cow/d, the WPCS:CSS to maximize the profit of dairy farmers was 16:84, 22:78, 44:56, and 88:12, respectively, and the land area needed to grow corn plants was 4.5, 31.4, 33.4, and 30.3 ha, respectively. The amount of corn available (ton DM/ha/yr) for other purposes saved from this land area decreased with higher producing cows. However, compared with high producing cows (30 kg/d milk), more low producing cows (10 kg/d milk) and more land area to grow corn and soybeans was needed to produce the same total amount of milk. Extra land is available to grow corn for a higher milk production, leading to more corn available for other purposes. Increasing ME content of CSS decreased the land area needed, increased the profit of dairy farms and provided more corn available for other purposes. At the optimal WPCS:CSS, MNE and enteric methane production was greater, but methane production per kg milk was lower, for high producing cows. Conclusion: The WPCS:CSS to maximize the profit for dairy farms increases with decreased milk production levels. At a fixed total amount of milk being produced, high producing cows increase corn available for other purposes. At the optimal WPCS:CSS, methane emission intensity is smaller and MNE is greater for high producing cows.

• 한국가구학회지
• /
• 제27권4호
• /
• pp.392-398
• /
• 2016

Wood-plastic composites (WPCs) composed of mainly wood flour and thermoplastics have attracted considerable attentions due to advantages of cost effectiveness, high durability, and microbial resistance. However, relatively poor fire resistance of WPCs from low thermal stability of wood and plastics prevents further uses. This study investigated the effect of expandable graphite (EG) and aluminium hydroxide (AH)/magnesium hydroxide (MH) on the properties of WPCs. The combined incorporation of both EG and metal hydroxide (i.e., AH or MH) into formulations leads to higher flexural modulus of filled composites compared to neat PP and WPC. In thermal properties, EG played an important role in improving thermal stability of filled composites by suppressing thermal decompositions of wood and PP. Moreover, EG showed better water absorption features. From this research, it can be said that EG and metal hydroxides have potentials as effective reinforcement, flame retardant, and moisture barrier.

• 한국화재소방학회논문지
• /
• 제24권6호
• /
• pp.120-125
• /
• 2010

주거 건축 및 가구산업의 자재로써 합성목재(Wood-Plastic Composites)는 점차 각광받고 있다. 본 연구에서는 합성목재의 연소특성을 살펴보기 위하여 한계산소지수 측정(ASTM D 2863) 및 콘칼로리미터 시험(ISO 5660-1)을 실시하였으며 또한 일반목재인 적송과 방부 처리를 한 방부목에 대하여도 동일한 시험을 통하여 합성목재와의 연소특성을 비교.검토하였다. 한계산소지수 측정결과 합성목재가 적송 및 방부목에 비해 낮게 측정되었다. 콘칼로리미터 시험결과 합성목재의 열방출률이 가장 높았고 또한, 최대 열방출률 및 평균 열방출률, 총 방출열량도 적송 및 방부목에 비해 높게 나타났다.

• 폴리머
• /
• 제37권2호
• /
• pp.204-210
• /
• 2013

첨가제(윤활제 및 산화방지제)와 용융혼합 조건(온도, 시간 및 로터 속도)이 폴리프로필렌(PP) 기반 WPC(wood polymer composite)의 기계적 특성에 미치는 영향을 조사하였다. WPC는 용융혼합 후 압축성형하여 제조하였다. 용융혼합 과정을 이해하기 위해 WPC 용융혼합물의 토크 변화를 측정하였다. 말레산무수물로 개질된 폴리프로필렌을 상용화제로, 나노점토를 보강재로 각각 사용하였다. WPC의 기계적 특성을 측정하기 위해 UTM과 충격시험기를 이용하였고 색차계를 이용하여 WPC의 용융혼합 조건에 따른 변색을 측정하였다. 기계적 특성 분석에 따른 최적용융혼합 조건은 $170^{\circ}C$, 15분, 60 rpm인 것으로 나타났다. 윤활제와 산화방지제의 함량이 증가할수록 WPC의 기계적 특성이 하락함을 확인하였다. 용융혼합 과정에서 목분만을 별도로 나중에 투입하는 이단계 방법이 전형적인 일단계 방법보다 WPC의 기계적 특성 향상에 더 효과적이었다.

• Journal of the Korean Wood Science and Technology
• /
• 제44권6호
• /
• pp.852-863
• /
• 2016

Wood-plastic composite (WPC) is a promising and sustainable material, and refers to a combination of wood and plastic along with some binding (adhesive) materials. In comparison to pure wood material, WPCs are in general have advantages of being cost effective, high durability, moisture resistance, and microbial resistance. The properties of WPCs come directly from the concentration of different components in composite; such as wood flour concentration directly affect mechanical and physical properties of WPCs. In this study, wood powder concentration in WPC was determined by Fourier transform near-infrared (FT-NIR) and Fourier transform infrared (FT-IR) spectroscopy. The reflectance spectra from WPC in both powdered and tableted form with five different concentrations of wood powder were collected and preprocessed to remove noise caused by several factors. To correlate the collected spectra with wood powder concentration, multivariate calibration method of partial least squares (PLS) was applied. During validation with an independent set of samples, good correlations with reference values were demonstrated for both FT-NIR and FT-IR data sets. In addition, high coefficient of determination (${R^2}_p$) and lower standard error of prediction (SEP) was yielded for tableted WPC than powdered WPC. The combination of FT-NIR and FT-IR spectral region was also studied. The results presented here showed that the use of both zones improved the determination accuracy for powdered WPC; however, no improvement in prediction result was achieved for tableted WPCs. The results obtained suggest that these spectroscopic techniques are a useful tool for fast and nondestructive determination of wood concentration in WPCs and have potential to replace conventional methods.

• 한국화재소방학회논문지
• /
• 제25권3호
• /
• pp.119-124
• /
• 2011

본 연구에서는 최근 조경 및 건축자재로서 각광받고 있는 합성목재의 화재위험성을 알아보기 위하여 콘칼로리미터 실험과 연기밀도 실험 장치를 이용하여 연기밀도 특성을 살펴보았다. 일반목재인 적송과 방부처리를 한 방부목에 대하여도 동일한 실험을 통하여 합성목재와의 연기밀도 특성을 비교하였다. 콘칼로리미터 실험결과 CO 및 $CO_2$ 발생량과 총 연기 발생량 값은 적송 및 방부목에 비해 합성목재가 높게 나타났다. 또한 연기밀도 실험 장치를 통한 최대연기밀도(Dm) 결과에서도 합성목재가 적송 및 방부목에 비해 높게 나타났다.