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Modification of urea-formaldehyde resin adhesives with blocked isocyanates using sodium bisulfite
Lubis, Muhammad Adly Rahandi,Park, Byung-Dae,Lee, Sang-Min Butterworth-Heinemann Ltd. 2017 International journal of adhesion & adhesives Vol.73 No.-
<P><B>Abstract</B></P> <P>Polymeric 4-4 diphenyl methane diisocyanate (pMDI) was blocked with an aqueous sodium bisulfite solution to obtain water-dispersible blocked pMDI (B-pMDI) resin with different HSO<SUB>3</SUB>/–NCO mole ratios for the modification of urea-formaldehyde (UF) resin. Fourier transform infrared (FTIR) spectra of the B-pMDI resin clearly showed that all isocyanate groups of the pMDI resin were successfully blocked by sodium bisulfite. As the HSO<SUB>3</SUB>/–NCO mole ratio increased, the de-blocking temperature of the B-pMDI resin also increased. Two addition levels (1% and 3%) of the B-pMDI resin with different HSO<SUB>3</SUB>/–NCO mole ratios were mixed with UF resins and used as an adhesive for plywood. The gel time of the UF/B-pMDI resins decreased to a minimum at a mole ratio of 0.9 and then increased with the HSO<SUB>3</SUB>/–NCO mole ratio, and was consistent with the peak temperature (<I>T</I>p). However, as the HSO<SUB>3</SUB>/–NCO mole ratio increased, the viscosity of the modified UF resins by 1% B-pMDI resin addition slightly increased, whereas those of modified resins with 3% B-pMDI resin addition rapidly increased. The adhesion strengths of plywood bonded with the hybrid resins were greater for 1% B-pMDI resin addition than for 3% B-pMDI resin addition. Formaldehyde emission of plywood bonded with the UF/B-pMDI resins significantly decreased up to 34% by the addition of B-pMDI resin at a mole ratio of 1.8. These results suggest that the modification of UF resins by mixing with water-dispersible B-pMDI resin can be a method for improving the water resistance and formaldehyde emission of UF resins for wood-based composites.</P>
LUBIS, Adelina,DALIMUNTHE, Ritha,ABSAH, Yeni,FAWZEEA, Beby Karina Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.3
This study aims to analyze the effect of corporate communication and service quality on loyalty mediating satisfaction. The population of this study is 384 Islamic bank customers in North Sumatra. This research is quantitative research using the survey method. The number of research samples was 384 customers. Characteristics of this research sample were (1) Savings customers who actively carried out transactions in Islamic banks (2) Savings customers who had used bank services for at least 1 year (3) Savings customers who used services directly and individually. The data analysis technique used in this study was the Partial Least Squares-Structural Equation Model (SEM-PLS) analysis technique, using Warp-PLS 3.0 software. This study investigates the largest Islamic banks in North Sumatra, namely Bank Syariah Mandiri, Bank BNI Syariah, and Bank BRI Syariah. The results show that company communication has a positive and significant effect on satisfaction, service quality has a positive and significant effect on satisfaction, company communication has a positive and significant effect on loyalty, service quality has a positive and significant effect on loyalty, satisfaction has a positive and significant effect on loyalty. There is also a significant effect of satisfaction on the relationship between company communication and loyalty, and the relationship between service quality and loyalty. This study contributes to Islamic banking to increase customer loyalty.
Brain Medical Image Retrieval Using Non-Negative Matrix Factorization and Canny Edge Detection
Ali Akbar Lubis,Suharjito 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.4
Disease conditions in the human brain can be detected by using medical image analysis. Content Based Image Retrieval of medical images can be used as an alternative to recognize the medical images of the human brain. In CBIR, feature extraction and recognition methods was an important feature because of medical image was different from the general image. In this study medical images that contain clinical information will be used as feature extraction using a canny edge detection and recognition features using non-negative matrix Factorization (NNMF). The purpose of this paper was to describe the use of canny edge detection and NNMF in CBIR. So CBIR could provide information on brain diseases and abnormalities. The results showed that the detection of disease in the human brain can be done by using both methods with good results if done preprocessing using histogram equalization.
Andri Maruli Tua Lubis,Erick Wonggokusuma,Aldo Fransiskus Marsetio 대한슬관절학회 2019 대한슬관절학회지 Vol.31 No.1
Purpose: Up to now, there is no feasible solution for stopping or reversing the degenerative process of osteoarthritis (OA). Our study evaluated the effect of intraarticular injection of growth hormone (GH) in OAinduced rabbit knees compared to hyaluronic acid (HA) and placebo.Materials and Methods: A total of 21 male, skeletally mature, New Zealand rabbits received an intraarticular type II collagenase injection for OA induction. Two weeks later, the rabbits were randomized into three groups based on the weekly intraarticular injection to be received: GH, HA, and saline. Injections were done for three consecutive weeks. Evaluation was done at 8 weeks after treatment, clinically using the lameness period, macroscopically using the Yoshimi score and microscopically using the Mankin score. Results: The shortest period of lameness was found in the GH group (15.9±2.12 days), compared to the HA group (19.4±1.72 days) and placebo group (25.0±2.94 days). There was a statistically significant difference in macroscopic scoring between groups (p=0.001) in favor of the GH group. There was also significant difference in the microscopic score between groups (p=0.001) also in favor of the GH group.Conclusions: Intraarticular injection of GH showed better clinical, macroscopic and microscopic results as compared to HA and placebo.
( Muhammad Adly Rahandi LUBIS ),( Bora JEONG ),( Byung-Dae PARK ),( Sang-Min LEE ),( Eun-Chang KANG ) 한국목재공학회 2019 목재공학 Vol.47 No.5
This work examined effects of the synthesis method and melamine content of melamine-urea-formaldehyde (MUF) resins on the bond-line features (i.e. resin penetration and bond-line thickness) in plywood. Two synthesis methods (MUF-A and MUF-B) and three melamine contents (5, 10, and 20%) were employed to prepare MUF resins. The MUF-A resins at three melamine contents were prepared by a simultaneous reaction of melamine, urea, and formaldehyde, while the MFU-B resins were prepared by reacting melamine at the same levels with formaldehyde followed by urea. The results showed that higher melamine content increased the viscosity of MUF-A and MUF-B resins. The resin penetration of MUF-A resins decreased by 48% while those of MUF-B resins increased by 16% at 20% melamine content. As a result, the MUF-A resins had greater bond-line thickness than those of MUF-B resins as the melamine content increased. The MUF-B resins resulted in thinner bond-line and greater resin penetration compared to those of MUF-A resins. The results suggested that MUF-B resins prepared with 20% melamine content had a proper combination of resin penetration and bond-line thickness that could produce plywood panel with a better adhesion performance.