Enhancement of Dimensional Stability of Polymer Composites Manufacturing Using Carbon Nanofibers

Materials ◽  
2005 ◽  
Author(s):  
Sudhir Gangireddy ◽  
Kuang-Ting Hsiao
Keyword(s):  
Residual Stress ◽  
Polymer Composites ◽  
Carbon Nanofibers ◽  
Dimensional Stability ◽  
Traditional Approach ◽  
Physical And Mechanical Properties ◽  
Good Precision ◽  
Composite Part ◽  
Polyester Composite ◽  
Dimensional Instability

Process induced residual stress arises in polymer composites as a result of resin shrinkage during cure cycle. When a shell-like composite part is demolded, these residual stresses result in change of dimensions such as spring-in, which is a phenomenon that the enclosed angles of the composite part are reduced due to process-induced residual stress. To have good precision in the composite part, the dimensional instability of enclosed angles must be controlled and/or compensated. The traditional approach is to estimate the spring-in and consequently correct the mold geometry to counterbalance the predicted dimensional instability. The success of such mold design practice relies on the past experience or by costly trial and error approach. In this paper, we present a new approach to reduce the spring-in by using Carbon Nanofibers (CNF). CNF have remarkable physical and mechanical properties and have excellent dimensional stability and hence may be useful in improving the dimensional stability of polymer composites. In this experimental study, we dispersed different fractions of CNF into fiberglass/polyester composite parts with corner angles and compared their spring-in angles after the composite parts were demolded. The results show that the CNF can effectively restrain the undesired deformation and improve the dimensional stability of polymer composites during manufacturing process.

Uphill Quenching of Aluminum Alloys

2019 ◽  
Author(s):  
Wellington da Silva Mattos ◽  
George Edward Totten ◽  
Lauralice de Campos Franceschini Canale
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Stress ◽  
Aluminum Alloys ◽  
Temperature Gradient ◽  
Dimensional Stability ◽  
Steam Chamber ◽  
Conventional Heat Treatment ◽  
Quenching Process ◽  
Uphill Quenching

This article describes the concept of uphill quenching process applied in the heat treatment of aluminum alloys. Uphill quenching is interesting since residual stress reductions of up to 80% has been reported. In addition, substantial improvements in dimensional stability have been achieved for several types of aluminum parts. Often, uphill quenching is applied after quenching and before aging during the heat treatment of aluminum alloys. The uphill quenching process consists of the immersion of the part in a cryogenic environment, and after homogenization of the temperature, the part is transferred to the hot steam chamber to obtain a temperature gradient that will maintain the mechanical properties gained with this process. The results obtained are lower residual stress and better dimensional stability. The aim of this article is to provide a review of this process and to compare it with conventional heat treatment.

scholarly journals Effect of punching on physical and mechanical properties of leathers: Focus on car seat covers

2019 ◽  
Vol 14 ◽  
pp. 155892501989056
Author(s):  
Eui Kyung Roh
Keyword(s):  
Mechanical Properties ◽  
Apparent Density ◽  
Coefficient Of Friction ◽  
Dimensional Stability ◽  
Physical And Mechanical Properties ◽  
Air Permeability ◽  
Car Seats ◽  
Car Seat

As a lot of time is spent in the car, the comfort of not only the car seat but also the car seat cover itself has become of increasing importance. With increasing use of ventilated seats, the control of the physical and mechanical properties of leather in response to punching has become of prime importance in the design of car seats. This study evaluated the changes in the physical and mechanical properties of leather due to punching and proposes optimum punching intervals for car seats. Sixteen types of leather, punched at three spatial intervals (2, 3, and 5 mm), were evaluated in terms of their apparent density, softness, coefficient of friction, warm-cool feeling, and mechanical properties. Leather punching affected its physical and mechanical properties. However, there were differences in punching intervals that significantly affected each property, including the mechanical properties. Depending on the performance required when developing a product, a suitable punching interval must be selected. Therefore, punching at 5 mm intervals is preferred for obtaining physical and mechanical properties similar to those of untreated leathers, and punching at 3 mm intervals is recommended for achieving more softness. On the contrary, punching at 2 mm intervals increases air permeability but decreases dimensional stability.

Grafting polyethylene glycol dicrylate (PEGDA) to cell walls of poplar wood in two steps for improving dimensional stability and durability of the wood polymer composite

Holzforschung ◽  
2016 ◽  
Vol 70 (10) ◽  
pp. 919-926 ◽  
Author(s):  
Youming Dong ◽  
Kaili Wang ◽  
Yutao Yan ◽  
Shifeng Zhang ◽  
Jianzhang Li
Keyword(s):  
Polyethylene Glycol ◽  
Dimensional Stability ◽  
Surface Hardness ◽  
Physical And Mechanical Properties ◽  
Contact Angles ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
Wood Polymer ◽  
Higher Dimensional ◽  
Peg Treatment

Abstract Polyethylene glycol (PEG) treatment is an effective approach to endow wood with higher dimensional stability (DS), which is still a concern under humid conditions. In this study, poplar wood was first treated with methacryloyl chloride to introduce methacryl groups in the cell wall. Then functional PEG served as modifier, and copolymerization was conducted in the second step to prepare PEG-diacrylate (PEGDA) modified samples. The resultant wood polymer composites (WPCs) were characterized by solid state NMR, field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). The physical and mechanical properties of the WPCs were also evaluated, such as anti-swelling efficiency (ASE), water uptake, dynamic hydrophilicity (contact angles), and thermal stability. The results show that the copolymerized WPC achieved 51.4% ASE with leaching <3.0%. Moreover, the surface hardness and water resistance of the wood are also greatly improved.

scholarly journals New Perspective on Wood Thermal Modification: Relevance between the Evolution of Chemical Structure and Physical-Mechanical Properties, and Online Analysis of Release of VOCs

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1145 ◽  
Author(s):  
Jiajia Xu ◽  
Yu Zhang ◽  
Yunfang Shen ◽  
Cong Li ◽  
Yanwei Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dimensional Stability ◽  
Chemical Structure ◽  
Low Cost ◽  
Physical And Mechanical Properties ◽  
Decay Resistance ◽  
Thermal Modification ◽  
Infrared Spectrometry ◽  
Dominant Component ◽  
New Perspective

Thermal modification (TM) is an ecological and low-cost pretreated method to improve the dimensional stability and decay resistance of wood. This study systematically investigates the relevance between the evolution of chemical structure and the physical and mechanical properties during wood thermal modification processes. Moreover, the volatility of compounds (VOCs) was analyzed using a thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TGA-FTIR) and a pyrolizer coupled with gas chromatography/mass spectrometer (Py-GC/MS). With an increase of TM temperature, the anti-shrink efficiency and contact angle increased, while the equilibrium moisture content decreased. This result indicates that the dimensional stability improved markedly due to the reduction of hydrophilic hydroxyl (–OH). However, a slight decrease of the moduli of elasticity and of rupture was observed after TM due to the thermal degradation of hemicellulose and cellulose. Based on a TGA-FTIR analysis, the small molecular gaseous components were composed of H2O, CH4, CO2, and CO, where H2O was the dominant component with the highest absorbance intensity, i.e., 0.008 at 200 °C. Based on the Py-GC/MS analysis, the VOCs were shown to be mainly composed of acids, aldehydes, ketones, phenols, furans, alcohols, sugars, and esters, where acids were the dominant compounds, with a relative content of 37.05−42.77%.

scholarly journals Plasma coating of carbon nanofibers for enhanced dispersion and interfacial bonding in polymer composites

2003 ◽  
Vol 83 (25) ◽  
pp. 5301-5303 ◽  
Author(s):  
Donglu Shi ◽  
Jie Lian ◽  
Peng He ◽  
L. M. Wang ◽  
Feng Xiao ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Carbon Nanofibers ◽  
Plasma Coating ◽  
Interfacial Bonding

Physical and Mechanical Properties of Five Heat-Treated Hardwood Species

2012 ◽  
Vol 472-475 ◽  
pp. 1132-1134
Author(s):  
Jin Sun ◽  
Xiao Bo Wang ◽  
Xiao Jing Wang ◽  
Yan Lin ◽  
Zhen Zhong Gao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Dimensional Stability ◽  
Negative Impact ◽  
Physical And Mechanical Properties ◽  
Betula Platyphylla ◽  
Fraxinus Mandshurica ◽  
Hardwood Species ◽  
Heat Treated ◽  
Betula Platyphylla Suk

Five hardwood species (Schima superba Gardn, kapur( Dryobalanops sp.), ash (Fraxinus mandshurica Rupr.), birch(Betula platyphylla Suk.), tauari (Couratari sp.)) were conducted the Heat treatment at 185°C.. The results indicated that the dimensional stability, modulus of elasticity (MOE) increased greatly while the wettability decreased after treatment. There was a negative impact of heat treatment on MORs.

Environmental Durability of Natural Fiber Reinforced Unsaturated Polyester Composite

2013 ◽  
Author(s):  
Mengyuan Liao ◽  
Umaru Semo Ishiaku ◽  
Zainal Arifin Mohd Ishak ◽  
Guijun Xian ◽  
Hiroyuki Hamada
Keyword(s):  
Mechanical Properties ◽  
Environmental Degradation ◽  
Natural Fiber ◽  
Unsaturated Polyester ◽  
Physical And Mechanical Properties ◽  
Vacuum Oven ◽  
Polyester Composite ◽  
Environmental Durability ◽  
Natural Climate ◽  
Automotive Interior

With an industrial increasing interest in sustainable, eco-efficient and green material’s application, natural fiber in polymer composite is guided to develop rapidly, especially kenaf nonwovens in making automotive interior trim parts with its comparative excellent strength and renewability. The objectives of this research are to investigate the environmental degradation behavior on the physical and mechanical properties of kenaf/unsaturated polyester nonwoven composites (KUNC) with special reference to the influence of different geographic natural climate ageing conditions. KUNC was prepared with needle-punched kenaf’s impregnation into unsaturated polyester resin assisted with vacuum oven following by hand lay-up molding. Natural environmental degradation was performed on KUNC by exposing the specimens to Kyoto(Japan), Shanghai(China) and Harbin(China) for a period of 3 months. Weight change and mechanical properties of degraded KUNCs in former three geographic positions in terms of tensile, flexural, impact and fracture toughness were measured instrumentally for ageing effect discussion and comparison. As expected, the aged specimens in those different positions all showed the dropped mechanical properties with weight increasing in varying degrees. Furthermore, the result of degradation level comparison among different positions revealed the positive correlation between increased weight percentages and dropped mechanical properties. In other words, dropped mechanical properties of the degraded composites with increasing weight were attributed to the effect of water, which deteriorates the interfacial properties of composites.

scholarly journals Effects of Resin Content on the Characteristics of Bamboo Oriented Strand Board Prepared from Strands of Betung, Ampel, and Their Mixtures

2021 ◽  
Vol 9 (3) ◽  
pp. 454-465
Author(s):  
Tengku Muhammad Renzy Hariz ◽  
Indra Agus Santosa ◽  
Muhammad Iqbal Maulana ◽  
Marwanto ◽  
Denni Prasetia ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Dimensional Stability ◽  
Oriented Strand Board ◽  
Physical And Mechanical Properties ◽  
Resin Content ◽  
Thickness Swelling ◽  
Higher Dimensional ◽  
Bambusa Vulgaris ◽  
Dendrocalamus Asper

The objectives of this research were to evaluate bamboo-oriented strand board (BOSB) characteristics made from betung (Dendrocalamus asper), ampel (Bambusa vulgaris), and their mixtures at two different contents (3% and 5%) of methylene diphenyl di-isocyanate (MDI) adhesives. The strands were steam-treated at 126°C for 1 h under the pressure of 0.14 MPa. Three-layered BOSBs with a target density of 0.7 g/cm3 were made with the size of 30 cm x 30 cm x 0.9 cm and a shelling ratio of 1:2:1 (face:core:back layers). The physical and mechanical properties of BOSB were evaluated following JIS A 5908 (2003) standard, and the results were compared with the CSA 0437.0 Grade O-1 standard. The results show that BOSB from the mixtures of betung and ampel bamboo strands has higher dimensional stability as shown by the decrease in water absorption and thickness swelling and higher mechanical properties than single BOSB. All BOSBs with 5% resin content have higher dimensional stability, MOE, and MOR than BOSB with 3% resin content. The physical and mechanical properties of all BOSB manufactured met the CSA 0437.0 Grade O-1 standard. This study proved that BOSBs from the mixture of betung and ampel strands have the potential to be developed due to having better physical and mechanical qualities than a single BOSB. Keywords: ampel (Bambusa vulgaris), bamboo oriented strand board, betung (Dendrocalamus asper), resin content, strand mixtures

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