Methacrylate-functionalized POSS as an efficient adhesion promoter in olefin-based adhesives

This study aims to investigate the effects of methacrylate-functionalized polyhedral oligomeric silsesquioxane (MA-POSS) on polyolefin-based adhesives. The so called adhesive was synthesized by the cooligomerization of 1-decene/9-decene-1-ol monomers using a Ti amine bis-phenolate catalyst, [Ti{2,2′-(OC₆H₂-4,6-^tBu₂)₂NHC₂H₄NH(OⁱPr)₂], which was subsequentlyacrylated via a simple reaction with methacryloyl chloride. Different weight fractions of MA-POSS nanoparticles were solution blended with synthesized adhesive and undergone curing reaction with blue light. Observation of a unique tan δ peak in dynamic mechanical thermal analysis (DMTA) curve was clear evidence that two employed moieties were miscible and only one hybrid polymeric phase was created. Most noticeably, significant increase in mechanical parameters was detected in the lower inclusion compositions, 0.2-1 wt% of MA-POSS, where flexural strength and flexural modulus were increased up to 99 and 110%, respectively. Furthermore, thermal stability of the synthesized nanocomposite enhanced dramatically by increasing MA-POSS weight fraction. Influence of employed nanoparticles on adhesion properties of synthesized nanocomposites was evaluated with tensile shear bond strength and pull off analysis. According to the adhesion results, the MA-POSS causes an adhesion promotion on the fabricated adhesive/POSS nanocomposites.     

Highly efficient supported AlCl3-based cationic catalysts to produce polyα-olefin oil base stocks

The main aim of this research is to decrease the amount of AlCl₃ content that is very corrosive and hazardous in the catalytic system, required for the α-olefin oligomerization without substantial change of final oil features. This was successfully achieved by supporting AlCl₃ on different carriers. More precisely, a series of supported bimetallic catalysts was synthesized by immobilization of AlCl₃ and TiCl₄ onto Al₂O₃, SiO₂, and mixed supports, that is, Al₂O₃/FeCl₃ and SiO₂/FeCl₃. It was found that silica and alumina-based catalysts had higher catalytic activities compared to support free AlCl₃; however, this enhancement for silica-based supports was more significant. According to gel permeation chromatography (GPC) results, the use of single supports, that is, Al₂O₃ and SiO₂, increased oligomer's molecular weight, while the application of mixed supports resulted in the decrease of molecular weight of the oligomers. Viscosity characteristics of the synthesized oligomers have also been studied at two different temperatures of 40 and 100°C (KV⁴⁰ and KV¹⁰⁰). The viscosity index (VI) values, derived from KV⁴⁰ and KV¹⁰⁰, of the prepared oligomers were in the range of 126–145. The molecular weight and termination mechanisms of the oligomers were studied by ¹H-NMR spectroscopy. The obtained results disclosed that the employed reaction conditions led to the production of oligomer chains with various structures including vinylidene (Vd), and di and three-substituted vinylene (2Vn, 3Vn) structures.     

Polybutadiene/polyhedral oligomeric silsesquioxane nanohybrid: investigation of various reactants in polyesterification reaction

Nano‐sized polyhedral oligomeric silsesquioxane (POSS) diol or ethylene glycol (EG) as diol monomer was incorporated into hydroxyl‐terminated polybutadiene (HTPBD) chain in the presence of fumaryl or thionyl chloride as extenders. Using these polyesterification reactions, two fumarate‐based polyesters and two polyester sulfites were synthesized. Each couple of polyesters and polyester sulfites includes a linear (diol:EG) and a nanohybrid macromer (diol:POSS). Full structural characterization was performed using Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopies. Gel permeation chromatography was undertaken to study polyesterification mechanisms by deconvolution of the obtained traces. Finally, differential scanning calorimetry, thermogravimetric analysis and cell culture were performed to evaluate the structure–property relationship for the synthesized macromers in comparison with unreacted HTPBD. © 2016 Society of Chemical Industry     

Poly1‐hexene: New impact modifier in HIPS technology

Poly1‐hexene was prepared using a conventional heterogeneous Ziegler–Natta catalyst and its stereoregularity was characterized using ¹³C‐NMR analysis. New kind of high impact polystyrene (HIPS) was prepared by radical polymerization of styrene in the presence of different amounts of synthesized poly1‐hexene (PH) as impact modifier (HIPS/PH) and compared with conventional high impact polystyrene with polybutadiene (HIPS/PB) as rubber phase. Scanning electron microscopy (SEM) revealed that the dispersion of poly1‐hexene in polystyrene matrix was more uniform compared with it in HIPS/PB. The impact strength of HIPS/PH was 29–79% and 80–289% higher than that in HIPS/PB and neat polystyrene, respectively. FTIR was used to confirm more durability of HIPS/PH samples toward ozonation. To study the effect of rubber type and amount on the T_gs of polystyrene, differential scanning calorimetry was employed. Results obtained from TGA demonstrated higher thermal stability of HIPS/PH sample in comparison with conventional HIPS/PB one. Our obtained results suggest new high impact polystyrene that in all studied aspects has better performance than the conventional HIPS. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43882.     

The effects of solvent and initiator on anionic ring opening polymerization of ϵ‐caprolactone: synthesis and characterization

Anionic ring opening polymerization of ?‐caprolactone was studied by using different amounts of two potassium activated initiators containing ethylene glycol (EG) and polyhedral oligomeric silsesquioxane (POSS) diol, in tetrahydrofuran and toluene as solvents. The synthesized hydroxyl terminated macromers and linear poly(?‐caprolactone) (PCL) were characterized by proton and carbon nuclear magnetic resonance and gel permeation chromatography (GPC) techniques. Results showed an increase in molecular weight as the monomer/initiator molar ratio increased from 100 to 151 and 202, while the molecular weight distribution (MWD) showed a minimum by monomer concentration increase. Moreover, POSS‐diol‐initiated PCLs showed a higher MWD than the polymers initiated with the EG initiator. This was attributed to the formation of a vesicular structure of POSS diols which was confirmed by optical microscopy. By deconvolution of GPC peaks, the best conditions to synthesize PCL with the narrowest MWD were selected. Finally, the effects of some other parameters were studied in more detail.     

Single-phase photo-cross-linkable adhesive synthesized from methacrylic acid-grafted 1-decene/9-decene-1-ol cooligomer

The cooligomerization of 1-decene with 9-decene-1-ol was conducted by using a Ti amine bis-phenolate catalyst. Light-curable adhesive was prepared by the reaction of methacryloyl chloride with the hydroxyl groups of the synthesized cooligomer, which led to the introduction of photo-polymerizable CC double bonds into the cooligomer chains. Comonomer insertion into 1-decene oligomeic chains and also methacryloyl chloride reaction with cooligomer were confirmed by both FT-IR and NMR spectroscopy. Three-point bending analysis results of cured adhesive sample (cured with blue light) showed flexural modulus and flexural strength values of 1.41 GPa and 1.66 MPa, respectively. Maximum weight loss temperature of 444°C showed high thermal stability of cured adhesive sample. In order to explore adhesion abilities of the synthesized adhesive to different substrates including polymethylmethacrylate (PMMA), polycarbonate (PC), polystyrene (PS), nylon and aluminum (Al), tensile shear bond strength, and peeling tests were conducted. Synthesized adhesive demonstrated tensile shear strength values of 1.28, 1.95, 1.10, 2.15, and 2.42 N/mm² for PMMA, PC, PS, nylon, and Al substrates, respectively. Furthermore, obtained adhesive indicated greater tendency to polar substrates in comparison to nonpolar ones by the factor of 16–95%. Obtained results suggested a new photo-curable adhesive with privileged features, which has capability to be used in high temperature applications.     

Effect of halocarbon promoters on polyethylene properties using MgCl2 (ethoxide type)/TiCl4/AlEt3/H2 catalyst system

In our previous study we found that addition of proper amount of halocarbons (HC) including chlorocyclohexane (CHC), chlorocyclopentane (CHP), butylchloride (BC), 1,4‐dichlorobutane (DCB), and chloroform (C) to the MgCl₂ (Ethoxide type)/TiCl₄/AlEt₃ catalytic system leads to a strong productivity improvement. In this study, the effect of these halocarbons on the properties of resulting polymers was investigated using H₂ as chain transfer agent at optimum HC/Ti molar ratio. The nature of halocarbon compound had a strong effect on polymer properties as well as on development of polymerization activity. Effect of halocarbon promoters on the polymer melt flow index (MFI), melt flow ratio (MFR), particle size distribution (PSD), bulk density, wax amount, crystallinity, and thermal properties of the polymers were studied. Results showed that, in the presence of halocarbons, polyethylenes with higher MFI and bulk density, broader MFR and lower wax amount have been obtained. Also, sieve analysis showed that, in the presence of halocarbons as promoter, polymers had better particle size distribution (PSD). DSC analysis showed that the T_m of PEs prepared with the different promoters were in the region commonly reported for HDPE and was not affected substantially by halocarbons, but, the crystallinity of the polymers has been improved using halocarbon promoters. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010