Effect of Testing Rate on Adhesion Properties of Benzoyl-Peroxide-Cured ENR 25/NBR Blend Adhesive Using Gum Rosin and Coumarone-Indene Resin as Tackifiers

Dependence of adhesion properties of benzoyl-peroxide-cured epoxidized natural rubber (ENR 25)/acrylonitrile-butadiene rubber (NBR) blend adhesive on testing rate was systematically studied. Coumarone-indene resin and gum rosin were used as tackifiers. Toluene was used as solvent throughout the study. The SHEEN hand coater was used to coat the adhesive on polyethylene terephthalate at 30 and 120 µm coating thickness. The adhesion properties were measured by a Lloyd adhesion tester operating at different rates of testing. Results showed that the loop tack, peel strength, and shear strength increased with increasing testing rate, an observation that was attributed to the viscoelastic nature of adhesive. In all cases, the adhesion properties of the adhesives also increased with increasing coating thickness.     

Electron‐beam irradiation of poly(vinyl chloride)/epoxidized natural rubber blends in presence of trimethylolpropane triacrylate

Electron‐beam initiated crosslinking of poly(vinyl chloride)/epoxidized natural rubber blends, which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20–200 kGy) and concentrations of TMPTA (1–5 phr). The gel content increased with the irradiation dose and the TMPTA level, although the increase was marginal at higher doses and higher TMPTA levels. Blends containing 3–4 phr TMPTA achieved optimum crosslinking, which in effect caused the maximum tensile strength (TS) at a dose of 70 kGy. A further addition of TMPTA caused a decline in the TS above 40 kGy that was due to embrittlement, which is a consequence of excessive crosslinking and the breakdown of the network structure. The possible formation of a more open network as a result of the breakdown of the network structure was further confirmed by the modulus results. Dynamic mechanical analysis (tan δ curve) and scanning electron microscopy studies on samples irradiated at 0 and 200 kGy were undertaken in order to gain further evidence on the irradiation‐induced crosslinking. The plasticizing effect of TMPTA prior to irradiation and the formation of microgels upon irradiation were also discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1926–1935, 2001     

The influence of surface structure of low industrial grade seaweed and semi‐refined carrageenan on mechanical and physical properties of natural rubber latex composites

Composites consisting of natural rubber (NR) latex as their matrix and low industrial grade seaweed (LIGS) and its extractive (semirefined carrageenan, SRC‐LIGS) as the filler were prepared via normal prevulcanization process. An analysis regarding the particle size and morphology of seaweed (LIGS and SRC‐LIGS), as well as surface properties and mechanical properties (tensile and tear properties) of NR latex composites, was consequently generated. Furthermore, post‐processing treatment for NR latex composites have also been studied, specifically involving leaching, heat aging, water absorption, and soil burial. The particle size of LIGS and SRC‐LIGS obtained was recorded to be lower than 100 μm. Thus, the results are indicative of SRC‐LIGS's role in improving the thermal properties of NR latex composites. After 8 weeks of soil burial, the incorporation of LIGS and SRC‐LIGS into the NR latex composites has accelerated biodegradation processes, thus highlighting their advantage as biodegradable fillers. These properties have consequently contributed to SRC‐LIGS/NR latex composites as a potential composite for use in biodegradable applications, such as polybag for pottery and plants. J. VINYL ADDIT. TECHNOL., 25:278–286, 2019. © 2018 Society of Plastics Engineers     

Multivariate calibration of fourier transform infrared spectra for determining thiobarbituric acid-reactive substance content in palm oil

Fourier transform infrared (FTIR) spectra of palm oil samples between 2900 and 2800 cm⁻¹ and 1800 and 1600 cm⁻¹ were used to compare different multivariate calibration techniques for quantitative determination of their thiobarbituric acid-reactive substance (TBARS) content. Fifty spectra (in duplicate) of palm oil with TBARS values between 0 and 0.25 were used to calibrate models based on partial least squares (PLS) and principal components regression (PCR) analyses with different baselines. The methods were compared for the number of factors, coefficients of determination (R ²), and accuracy of estimation. The standard errors of prediction (SEP) were calculated to compare their predictive ability. The calibrated models generated three to eight factors, R ² of 0.9414 to 0.9803, standard error of estimation (SEE) of 0.0063 to 0.0680, and SEP of 1.20 to 6.67.     

Evaluation of different types of synthetic adsorbents for carotene extraction from crude palm oil

Palm carotene was successfully concentrated from crude palm oil (CPO) by an adsorption process using synthetic adsorbents followed by solvent extraction. This process was a modified process for separation of palm carotene from CPO by adsorption chromatography with a synthetic polymer adsorbent. Carotene was concentrated to about 15,000 ppm, which is about 25 times the original concentration in CPO. Carotene recovery varied from 30 to 62% depending on the process conditions. Different types of adsorbents, combinations of adsorbents, and adsorbent/CPO ratios were evaluated to determine the effect on the percentage of carotene extracted. Commercial synthetic adsorbents HP 20 (styrene-divinyl copolymer); synthetic aromatic porous resin SP 850, SP 825; and synthetic adsorbents Relite Exa 32 and Relite Exa 50 were capable of adsorbing substantial amounts of carotene from CPO. Combinations of adsorbents types HP 20 and SP 850 slightly increased the percentage of carotene extracted. An adsorbent/CPO ratio of 4 was most suitable for this process for optimal recovery and concentration of carotene.     

Adhesion property of crosslinked epoxidized (natural rubber)/(acrylonitrile‐butadiene) rubber blend adhesives in the presence of petro resin tackifier

Loop tack, peel strength, shear strength, and morphology of (benzoyl peroxide)‐cured epoxidized natural rubber (ENR 25)/(acrylonitrile‐butadiene) rubber (NBR) blend adhesive were investigated by using petro resin as the tackifying resin. Benzoyl peroxide loading varied from 1 to 5 parts by weight per hundred parts of resin (phr), whereas the petro resin loading was fixed at 40 phr. A SHEEN hand coater was used to coat the adhesive on the polyethylene terephthalate substrate at 30 μm and 120 μm coating thicknesses. (ENR 25)/NBR adhesive was crosslinked at 80°C for 30 min prior to the determination of adhesion strength by a Lloyd adhesion tester operating at 10–60 cm/min. Results show that maximum loop tack and peel strength occur at 2 phr of benzoyl peroxide loading, whereby optimum cohesive and adhesive strength are obtained. However, shear strength increases with increasing benzoyl peroxide concentration, an observation that is associated with the steady increase in the cohesive strength. Scanning electron microscopy micrograph shows that little adhesive remained on the substrate at 0 phr compared with 2 phr of benzoyl peroxide loading, indicating that crosslinking increases the peel strength of the adhesive. In all cases, the adhesion properties increase with coating thickness and testing rate . J.VINYL ADDIT. TECHNOL., 24:93–98, 2018. © 2015 Society of Plastics Engineers     

Crosslinking of fibers via azide–alkyne click chemistry: Synthesis and characterization

There has been growing interest in fiber modification for several industrial applications. The modifications have mostly been done to improve the fiber properties. However, the information regarding fiber modification via click chemistry is still limited. In this work, two strategies of click chemistry are evaluated for modifying commercial paper without the addition of copper catalyst. The first strategy is the direct reaction between azidated fiber and propargylated fiber, and the second strategy is to bridge azidated fiber with a self‐made alkyne terminal crosslinker. Native and chemically modified fibers were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and ¹H‐NMR spectroscopy. The effects of the two clicking strategies on the fiber were further investigated by making handsheets. In terms of mechanical properties, the bridge‐clicking strategy was found to produce better handsheets than the direct‐clicking strategy. These modified fibers would be an interesting application for the packaging and printing industries. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43576.