Copolymer Poly Ethylene Research Articles

Transform Rice Husk and Recycled Polyethylene into High Performance Composites: Using a Novel Compatibilizer to Infiltratively Enhance the Interfacial Interactions

Rice husks are the fine crop residue used to prepare the industrial wood-like products by melt-blending with polymers. However, most wood-like products are highly filled with natural fibers in order to decrease the cost of the products, as it causes weak interfacial compatibility between the natural fibers and polymers. To successfully prepare a high performance wood-like product, the interfacial compatibility is the key problem that need to be solved. Moreover, the interfacial interactions at the gaps and voids around the natural fibers can enhance the interfacial compatibility of the composites. There is little research focusing on the interfacial interactions at these gaps and voids. In this paper, the multi-monomer graft copolymers of polyethylene (GPE) were used as the compatibilizers for the rice husk (RH) highly filled recycled polyethylene (rPE) composites. How the GPE affected the interfacial compatibility of the composites and the resulting mechanical properties, water resistance, thermal stability and rheological properties of rPE/RH composites were investigated. Results show that GPE could enhance the interfacial interactions of rPE/RH composites by infiltrating into the gaps and voids around RH. The strong interfacial interactions of the composites primarily came from the chemical reactions and physical interactions between RH and GPE. The mechanical properties, water resistance and thermal stability of the composites increased with the increase in GPE loadings. The preferable loadings of GPE were approximately at 8 phr. Meanwhile, GPE could improve the processing properties of the composites.

Joining Mechanism of Dissimilar Materials such as Metal and Plastic Sheets by Friction Lap Joining

It is difficult to join dissimilar materials such as metallic material and polymer. We have investigated to join Aluminum alloy and high density polyethylene (PE) and ethylene acrylic acid copolymer (EAA) using Friction Lap Joining (FLJ) and then concluded EAA could be strongly joined with Aluminum alloy. PE could not be joined without anodizing. We have considered that EAA has a polar functional group, COOH. On the contrary, PE cannot be joined to an as-received aluminum alloy, because PE has no polar functional group. So, we have tried to confirm this mechanism with XPS and FTIR to investigate the interface between anodized surface and that of polymer. We find that the possibility of chemical bonding arises between O-H in COOH and O in Al2O3or O in C=O and O in Al2O3 at elevated temperature.

Synthesis of poly(ω-pentadecalactone)-b-poly(acrylate) diblock copolymers via a combination of enzymatic ring-opening and RAFT polymerization techniques

Herein the first reported preparation of diblock copolymers of the polyethylene-like polyester poly(ω-pentadecalactone) (PPDL) via a combination of enzymatic ring-opening polymerization (eROP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization techniques is described. PPDL was synthesized via eROP using Novozyme 435 as a catalyst and a bifunctional initiator/chain transfer agent (CTA) appropriate for the eROP of ω-pentadecalactone (PDL) and RAFT polymerization of acrylic and styrenic monomers. Chain growth of the PPDL macro-CTA was performed to prepare acrylic and styrenic diblock copolymers of PPDL, and demonstrates a facile, metal-free, and “greener” alternative to preparing acrylic diblock copolymers of polyethylene (PE). Diblock copolymer architecture was substantiated via analysis of 1H NMR spectroscopic, UV-GPC chromatographic, DSC onset crystallization (Tc), and MALDI-ToF mass spectrometric data. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3326–3335

Storage solutions for excavated textiles: tending to their recalcitrant behaviour

This paper discusses the selection of packaging and storage means that facilitate the preservation, protection and managerial needs for a group of excavated textiles where their physical and chemical properties have been unrecognisably altered as a result of the burial process (in this case mineralisation). The newly acquired properties include a significant loss in weight (possibly due to mineralisation causing dehydration), extreme hydrophobia, brittleness and zero mechanical strength and elasticity. Developing an appropriate packaging and storage method depends on the methodology employed, the system selected and the materials used. The box-in-box method was selected for better controlling environmental parameters. The textiles were systematically organised in a way that they are stable and readily accessible with minimum handling. The materials used included open and close-cell polyethylene foam, copolymer polyethylene and polypropylene board, non-woven polyethylene fabric and the antistatic type of polyester film. All materials and methods applied exhibit great versatility and are potentially useful for conservators in similar situations.

The use of polyethylene copolymers as compatibilizers in carbon fiber reinforced high density polyethylene composites

Abstract In the current study, three different commercially available copolymers are used as compatibilizer in carbon fiber (CF) reinforced high density polyethylene (PE) based composites. Polyethylene grafted maleic anhydride (PE-g-MA), a random terpolymer of ethylene, acrylic ester and maleic anhydride (LOT-MA) and a random copolymer of ethylene and glycidyl methacrylate (LOT-GMA) are used as compatibilizers. The compatibilizers are used at three concentrations of 1.5, 3 and 6 wt%. The type and amount of compatibilizers on the tensile, impact, flexural, thermomechanical and morphological properties of composites are investigated. The use of coupling agents increases the mechanical properties of composites regardless of their type. The maximum increase in mechanical properties is observed at different concentrations of compatibilizer depending on the test type and compatibilizer type. The effectiveness of the compatibilizers is ranked as follow: LOT-MA > LOT-GMA > PE-g-MA in all mechanical tests. A correlation is observed between the effectiveness of compatibilizers and their polar group content. The higher polar group content causes the higher improvement in mechanical tests studied in this work.

Enhanced Water Vapor Transmission through Porous Membranes Based on Melt Blending of Polystyrene Sulfonate with Polyethylene Copolymers and Their CNT Nanocomposites.

A novel concept for the use of an immiscible and non-meltable polymer, such as sodium polystyrene sulfonate (PSSNa), in order to prepare polyethylene non-woven breathable membranes is described. Membranes were fabricated by melt compounding of properly functionalized PE (P(E-co-AA)) and PSSNa (P(SSNa-co-GMA)) copolymers in the presence of water soluble polyethylene glycol (PEG). The inability of PSSNa derivatives to be melted was overcome by using PEG, which was easily meltable thus inducing PSSNa processability improvement. PEG was removed after membrane fabrication and therefore also acted as a porogen. Carbon nanotubes, functionalized with PSSNa moieties or alkyl groups, were also incorporated in the membranes with the aim of improving the porous connectivity and increasing the water vapor transmission rate. The morphology of the membranes was investigated through Scanning Electron Microscopy (SEM). Water vapor transmission rate (permeation) (WVTR) measurements for the porous membranes showed increased values in comparison with the neat PE ones. A further increase of WVTR was observed with the addition of CNTs to the polymer membranes.

Poly(THF-co-cyano ethylene oxide): Cyano Ethylene Oxide (CEO) Copolymerization with THF Leading to Multifunctional and Water-Soluble PolyTHF Polyelectrolytes

Cyano-functional polyether copolymers based on THF were prepared via cationic ring-opening copolymerization of THF with cyano ethylene oxide (CEO). The CEO content of poly(tetrahydrofuran) (polyTHF) based copolymers varied from 3.3 to 29.3%, and molecular weights ranged from 5100 to 31900 g·mol–1 with Mw/Mn in the range of 1.31 to 1.74 (SEC in THF, PS standards). The polymerization was conducted with methyl trifluoromethanesulfonate (MeOTf) as an initiator. Kinetic studies concerning incorporation of both monomers were performed via NMR spectroscopy. The cyano groups at the poly(THF-co-CEO) copolymers enable direct access to amino (polyTHF–NH2) and carboxyl groups (polyTHF–COOH) in facile one-step procedures, respectively. The modified copolymers were characterized via NMR, MALDI–ToF mass, and FT-IR spectroscopy. Thermal properties of the materials were studied via differential scanning calorimetry (DSC), demonstrating a gradual decrease of the melting points with increasing amount of CEO in the copolymer...

Three-dimensional printing of biocompatible scaffolds for tissue engineered constructs

The formation of porous matrix structures (scaffolds) from biocompatible polymers and their composites with finely dispersed hydroxyapatite via air pressure–aided 3D printing and digital light processing (DLP) is studied. A triblock copolymer (polyethylene glycol/poly-e-caprolactone/polyethylene glycol) and polyethylene glycol diacrylate served as raw polymer materials. The internal structure and surface morphology of the resulting scaffolds and the correspondence of their architectonics to the initial 3D virtual models are analyzed by means of optical and scanning electron microscopy.

Azidated Ether-Butadiene-Ether Block Copolymers as Binders for Solid Propellants

Polymeric binders for solid propellants are usually based on hydroxyl-terminated polybutadiene (HTPB), which does not contribute to the overall energy output. Azidic polyethers represent an interesting alternative but may have poorer mechanical properties. Polybutadiene–polyether copolymers may combine the advantages of both. Four different ether-butadiene-ether triblock copolymers were prepared and azidated starting from halogenated and/or tosylated monomers using HTPB as initiator. The presence of the butadiene block complicates the azidation step and reduces the storage stability of the azidic polymer. Nevertheless, the procedure allows modifying the binder properties by varying the type and lengths of the energetic blocks.

Environmentally-safe and transparent superhydrophobic coatings

An environmentally-safe, water-borne coating consisting of titania nanoparticles and fluorine-free polyethylene copolymers, forming a transparent, substrate-independent, superhydrophobic water barrier.

Describing and quantifying the chemical composition distribution in unimodal and multimodal ZN‐polyethylene using CRYSTAF

ABSTRACTA new approach in describing and quantifying the chemical composition distribution (CCD) in Ziegler–Natta‐polyethylene copolymers was developed by using crystallization analysis fractionation (Crystaf). Copolymers of ethylene and α‐olefins (1‐butene and 1‐hexene) polymerized with different ZN catalyst systems were analyzed. Distinct differences in the CCD between the different polymer types (catalyst‐cocatalyst system and comonomer type) were observed and could be quantified. Same approach was applied to 2‐dimensional fractionation technique, cross fractionation chromatography, to describe and quantify the CCD of multimodal polyethylene copolymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43089.

Synthesis of glutamic-modified polyether copolymer as a novel non-phosphorous inhibitor for calcium carbonate scales in cooling water systems

A novel non-phosphorous copolymer acrylic acid-allyloxy polyethoxy glutamate (AA-APEU) had been synthesized and developed as an efficient calcium carbonate scale inhibitor for cooling water systems. The structure of the new copolymer was characterized by Fourier transform infrared spectra and 1H NMR. The inhibition property of the non-phosphorous copolymer toward CaCO3 in the artificial cooling water was studied through static scale inhibition tests. It was found that AA-APEU exhibited excellent ability to control calcium carbonate scale, with approximately 71.8% calcium carbonate inhibition at a level of 8 mg/L. The micromorphology and crystal of calcium particles were investigated with a combination of scanning electronic microscopy and X-ray powder diffraction analysis, respectively.

Blossom Morphology and Correlative Performance Improvement of Recycled Polyethylene/Wood Flour Composites with Steam-Activated Interfaces

Interfacial compatibility plays a key role in the performances of natural fiber-reinforced composites. The measures commonly used to improve the interfacial compatibility focus more on the addition of various compatibilizers than on the structural modification of the natural fiber. In this paper, an attempt was made to enlarge the interfacial interaction areas of the recycled polyethylene (rPE)/wood flour (WF) composites by steaming the WF. Multi-monomer graft copolymers of polyethylene (GPE) were used as compatibilizers for the composites. How the enlarged interfaces affected the morphology, mechanical properties, water resistance, thermal stability, and dynamic rheological properties of the rPE/WF composites was investigated. The steaming process was able to enlarge the voids of the WF and therefore activate more interfaces for interactions. It was found that the interfacial morphology of the composites was affected by the degree of interfacial compatibility of the composites and so was characterized by various distinctive blossom shapes having a variation of compositions. With the help of GPE, the steaming process was able to significantly improve the interfacial compatibility of the composites and therefore improve the mechanical properties, water resistance, thermal stability, and dynamic rheological properties of the composites.

Studies on the Application of Filter‐Based IR Detector for Polyolefin Characterization with HT‐SEC

SummaryEven though polyolefins are simple polymers from a chemical structure point of view, their full characterization in practice is still an intriguing task. Basic macromolecular characteristics of polyethylene or polypropylene like molar mass moments and their distributions (MMD) but also chain conformation and thus information on long‐chain branching, can be addressed with high‐temperature size‐exclusion chromatography (HT‐SEC). Hyphenation of infrared detection to size‐exclusion chromatography expands possibilities of SEC even more and allows to reveal comonomer incorporation across molecular weight and thus generate a fingerprint of a given catalytic system used in polyolefin synthesis. Multiband filter‐based infrared detector gives an easy and fast access to so‐called short chain branching distribution (SCB) vs MMD by coupling to HT‐SEC. In this work, we summarize recent findings on application of a filter‐based IR detector (IR5‐MCT) towards characterization of polyolefins synthesized with different catalytic systems and varying comonomer types. It is found that for copolymers of polyethylene with 1‐butene, 1‐hexene or 1‐octene (non‐C3), one linear calibration line can be used in the range up to 70 CH3/1000TC, thus covering the range necessary for common applications like for instance HDPE or LLDPE. For ethylene‐propylene copolymers (C3), over the broad range up to 333 CH3/1000TC, the calibration line is best fitted to a second order polynomial. C3 copolymers show a different behavior compared to non‐C3 copolymers, irrespective the amount of comonomer incorporated in the polymer. We show that mixtures of PP and PE homopolymers result in equivalent response as the copolymers of the same average composition and thus can also be used to set up calibration lines. Based on this evaluation practical aspects of IR5‐MCT calibration are discussed.

Cationic Copolymerization of 3,3-Bis(hydroxymethyl)oxetane and Glycidol: Biocompatible Hyperbranched Polyether Polyols with High Content of Primary Hydroxyl Groups.

The cationic ring-opening copolymerization of 3,3-bis(hydroxymethyl)oxetane (BHMO) with glycidol using different comonomer ratios (BHMO content from 25 to 90%) and BF3OEt2 as an initiator has been studied. Apparent molecular weights of the resulting hyperbranched polyether copolymers ranged from 1400 to 3300 g mol(-1) (PDI: 1.21-1.48; method: SEC, linear PEG standards). Incorporation of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All hyperbranched polyether polyols with high content of primary hydroxyl groups portray good solubility in water, which correlates with an increasing content of glycerol units. Detailed NMR characterization was employed to elucidate the copolymer microstructures. Kinetic studies via FTIR demonstrated a weak gradient-type character of the copolymers. MTT assays of the copolymers (up to 100 μg mL(-1)) on HEK and fibroblast cell lines (3T3, L929, WEHI) as well as viability tests on the fibroblast cells were carried out to assess the biocompatibility of the materials, confirming excellent biocompatibility. Transfection efficiency characterization by flow cytometry and confocal laser microscopy demonstrated cellular uptake of the copolymers. Antiadhesive properties of the materials on surfaces were assessed by adhesion assays with fibroblast cells.

Tumor-targeting, pH-sensitive nanoparticles for docetaxel delivery to drug-resistant cancer cells.

The attachment of polyethylene glycol (PEG) increases the circulation time of drug-containing nanoparticles; however, this also negatively affects cellular uptake. To overcome this problem, unique lipid polymer hybrid (LPH) nanoparticles were developed with a pH-responsive PEG layer that detached prior to cell uptake. Docetaxel (DTX) was incorporated into the lipid core of the nanoparticles, which was then shielded with the pH-responsive block co-polymer polyethylene glycol-b-polyaspartic acid (PEG-b-PAsp) using a modified emulsion method. The optimized LPH nanoparticles were ~200 nm and had a narrow size distribution. Drug release from DTX-loaded LPH (DTX-LPH) nanoparticles was pH-sensitive, which is beneficial for tumor targeting. More importantly, DTX-LPH nanoparticles were able to effectively induce apoptosis in cancer cells. The negative surface charge and PEG shell of vehicle remarkably enhanced the blood circulation and physiological activity of DTX-LPH nanoparticles compared with that of free DTX. The nanoparticles were also found to reduce the size of tumors in tumor-bearing xenograft mice. The in vivo anticancer effect of DTX-LPH nanoparticles was further confirmed by the elevated levels of caspase-3 and poly ADP ribose polymerase found in the tumors after treatment. Thus, the results suggest that this novel LPH system could be an effective new treatment for cancer.

A facile synthesis of catechol‐functionalized poly(ethylene oxide) block and random copolymers

ABSTRACTHerein we develop a facile synthetic strategy for the functionalization of well‐defined polyether copolymers with control over the number and location of catechol groups. Previously, the functionalization of polyethylene oxide (PEO)‐based polymers with catechols has been limited to functionalization of the chain ends only, hampering the synthesis of adhesive and antifouling materials based on this platform. To address this challenge, we describe an efficient and high‐yielding route to catechol‐functionalized polyethers, which could allow the effects of polymer architecture, molecular weight, and catechol incorporation on the adhesive properties of surface‐anchored PEO to be studied. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2685–2692

Improving the performances of polyethylene/sisal fiber composites by infiltratively compatibilizing the multi-scale interfaces

Sisal fiber (SF) is a good raw material to prepare natural fiber composites (NFCs) by blending it with plastics. However, most NFCs are highly filled with natural fibers in order to decrease the cost of products that causes the weak interfacial compatibilities between the natural fibers and polymers. To successfully prepare a high-performance NFC, the interfacial compatibility is the key problem that should be disposed. In this paper, the graft copolymers of polyethylene (GPE) were used as the infiltrative compatibilizers for SF-filled recycled polyethylene (rPE) composites. How GPE affected the interfacial compatibility and performances of rPE/SF composites were investigated. Results show that the mechanical properties, water resistance and thermal stability of the composites increased with the increase in GPE. The improved interfacial interactions restrained the movement of rPE chains, resulting in the decreasing of crystallinity of the composites. GPE were favorable to improve the rheological properties of the composites. The scanning electron microscopy observation discovered that GPE promoted the formation of infiltrative interfacial interactions that primarily came from the chemical and physical interactions between SF and GPE.

Preparation, Characterization and Properties of Reactive Type Dripping Agent Tween 60-IAH and Their Grafting Copolymer With Linear Low Density Polyethylene

A kind of reactive type dripping agent (Tween 60-IAH) was synthesized with polyethylene glycol sorbitan monostearate (Tween 60) and itaconic anhydride (IAH) as main starting materials. The chemical structure of Tween 60-IAH was characterized by means of Fourier transform infrared (FT-IR) spectroscopy. The effect of reaction time on conversion of Tween 60-IAH was studied. The results of thermogravimetric analysis (TGA) measurement demonstrated that Tween 60-IAH exhibited a better thermal stability than Tween 60. Grafting copolymer of linear low density polyethylene (LLDPE) with Tween 60-IAH was prepared in twin-screw extruder. Thermal and rheological properties of grafted LLDPE samples were investigated with differential scanning calorimetry (DSC) and rotational rheometer. Crystallization temperatures of grafted LLDPE were higher than that of LLDPE. Complex viscosities of grafted LLDPE at high shear rates were lower than that of LLDPE. The dripping properties of film samples were investigated at 60°C.

Synthesis and physical properties of highly branched perfluorinated polymers from AB and AB2 monomers

ABSTRACTHighly branched perfluorinated aromatic polyether copolymers were prepared from the polycondensation of the AB2 monomer, 3,5‐bis[(pentafluorobenzyl)oxy]benzyl alcohol with a variety of fluoroaryl and alkyl bromide AB comonomers. The structures and comonomer distribution of the resulting polymers were characterized in detail. 1H NMR data from kinetic trials illustrated that perfluoroaryl AB comonomer distribution correlated to AB comonomer sterics. 19F NMR data revealed that fluorinated AB monomers and 3‐bromo‐1‐propanol AB monomers were distributed within the AB2 polymer backbone, while longer alkyl bromide AB monomers, 6‐bromo‐1‐hexanol, were mostly distributed along hyperbranched polymer chain ends. In general, as AB comonomer incorporation increased for nonsterically hindered copolymers, thermal decomposition onset increased and glass transition temperatures decreased. The combined data demonstrated the effect of comonomer distribution and sterics on physical properties of AB2‐based polymer systems. The resulting materials were used to cast thin polymer films for measurement of contact angle, which were shown to be directly related to comonomer content. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1880–1894