Intrinsic styrene/maleic anhydride copolymer foam; a new green foaming technology

DSM has developed a new foaming technology based on carbon dioxide released via a controlled chemical reaction through catalyzed decarboxylation of SMA, a copolymer of Styrene (S) and maleic anhydride (MA). This carbon dioxide is thus used as an environmentally friendly blowing agent to generate intrinsically foamed SMA-based materials. The modulus of the foam exceeds by far (factor of 2–3) the modulus of common thermoplastic foams based on e.g. PS. The tensile strength is also higher (10%). This opens up many opportunities for SMA foams in structural applications. One example is roofliners. SMA has also been successfully applied as a chemical blowing agent (e.g. in combination with ABS) for the production of a high-density foam on an injection moulding machine or an extruder. In this paper the chemical background, processing, properties and some applications of intrinsically foamed SMA will be discussed.     

Effect of Cement on Properties of Inverted Emulsions and Polymers from Vinyl Monomers with Acid Anhydride-Adducted Polypropylene Glycol

Abstract

Adduct polymer (PPGMA) prepared from polypropylene glycol and maleic anhydride was found to give stable inverted emulsions when mixtures of cement, water, and vinyl monomers were vigorously stirred in the presence of PPGMA. In this case, the carboxyl groups of PPGMA were neutralized with metal ions generated from the cement into neutralized PPGMA which acts as an effective W/O type emulsifier. The inverted emulsions containing cement gave a new type of polymer-cement composites by polymerization of the vinyl monomers and also by hardening of the cement. Water-free composites were easily obtained by removing evaporative water. The effect of cement on the physical properties of the water-free composites was remarkable. Further, the use of mixed fillers of cement and Al(OH)₃ was found to improve the flame-retardant properties of the composites; however, increasing the Al(OH)₃ content in the fillers resulted in a decrease in the physical properties. Generally, the composites have improved resistance to acid media in which the usual foamed hydrated cement is eroded.     

Tensile,thermal, and antibacterial characterization of composites of cellulose/modified Pennisetum purpureum natural fibers with in situ generated copper nanoparticles

Eco-friendly all cellulose composites were developed using cellulose as matrix and nanocomposite (in situ generated copper nanoparticles modified Napier Grass Fibers (NGFs)) as fillers for the antibacterial applications. The content of the nanocomposite filler was increased from 1?wt.% to 5?wt.% in the cellulose matrix. All these composites were characterized by Scanning Electron Microscopy (SEM), Tensile, Thermo Gravimetric Analysis (TGA), and antibacterial tests. SEM-EDX analysis revealed the in situ generation of copper nanoparticles on the surface of the films. Further, all cellulose composites showed good thermal stability. A minimum of 30% increase in char residue was observed in all cellulose nanocomposites compared to matrix. Antibacterial analysis indicated an excellent clear zone formation against both Gram Negative (Escherichia coli) and Gram Positive (Staphylococcus) bacteria. Hence, all these cellulose nanocomposite films can be considered as antibacterial packaging and dressing materials in medical field.     

Thermal and dynamic mechanical properties of poly(propylene carbonate)

Summary Thermal and dynamic mechanical properties of carbon dioxide and propylene oxide alternative copolymer, poly(propylene carbonate) (PPC), and the end-capped PPC with maleic anhydride were investigated by means of TG and DMA. A master curve of the storage modulus vs. frequency can be deduced from the isochronal curves. Physical parameters of both plain and MA end-capped PPC were discussed. The results showed that for maleic anhydride (MA) end-capping PPC, an improvement of its thermal stability and mechanical properties accompanied with some modifications of the viscoelastic behavior were obtained.     

Melt modification of poly(styrene‐co‐maleic anhydride) with alcohols in the presence of 1,3‐oxazolines

Various copolyesteramides were prepared by melt compounding at 220 °C involving reaction of poly(styrene‐co‐maleic anhydride), SMA, with 6, 17, and 28 wt % maleic anhydride content, and 1‐dodecanol, C12OH, in the presence of 2‐undecyl‐1,3‐oxazoline, C11OXA. Copolymer architectures were examined by means of ¹H NMR, FTIR, DSC, and TGA using model compounds prepared via solution reactions. While conversion of anhydride with alcohol was poor due to the thermodynamically favored anhydride ring formation, very high conversions were achieved when stoichiometric amounts of C11OXA were added. According to spectroscopic studies esteramide groups resulted from reaction of oxazoline with carboxylic acid intermediate. In the absence of alcohol, C11OXA reacted with anhydride to produce esterimides. Effective attachment of flexible n‐alkyl side chains via simultaneous reaction of C12OH and C11OXA resulted in lower glass‐transition temperatures of copolyesteramides. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1222–1231, 2000     

Polymers from renewable resources. II. A study in the radio chemical grafting of poly(styrene‐alt‐maleic anhydride) onto cellulose extracted from pine needles

A binary mixture of styrene and maleic anhydride has been graft copolymerized onto cellulose extracted from Pinus roxburghii needles. The reaction was initiated with gamma rays in air by the simultaneous irradiation method. Graft copolymerization was studied under optimum conditions of total dose of radiation, amount of water, and molar concentration previously worked out for grafting styrene onto cellulose. Percentage of total conversion (Pg), grafting efficiency (%), percentage of grafting (Pg), and rates of polymerization (R_p), grafting (R_g), and homopolymerization (R_h) have been determined as a function of maleic anhydride concentration. The high degree of kinetic regularity and the linear dependence of the rate of polymerization on maleic anhydride concentration, along with the low and nearly constant rate of homopolymerization suggest that the monomers first form a complexomer which then polymerizes to form grafted chains with an alternating sequence. Grafting parameters and reaction rates achieve maximum values when the molar ratio of styrene to maleic anhydride is 1 : 1. Further evidence for the alternating monomer sequence is obtained from quantitatively evaluating the composition of the grafted chains from the FT‐IR spectra, in which the ratio of anhydride absorbance to aromatic (CC) absorbance for the stretching bands assigned to the grafted monomers remained constant and independent of the feed ratio of maleic anhydride to styrene. Thermal behaviour of the graft copolymers revealed that all graft copolymers exhibit single stage decomposition with characteristic transitions at 161–165°C and 290–300°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1763–1769, 1999     

Investigation of natural rubber composites with addition of montmorillonite fillers using thermal analysis

This paper is devoted to the investigation of the properties of the natural rubber composites prepared using the cation exchanged-montmorillonite fillers. The characteristics of the montmorillonite fillers were studied by Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). These characterized fillers were used to preparation of the natural rubber composites, which were submitted to measurements of dynamic-mechanical thermal analysis (DMTA) and vulcanizing characteristics (M _H, M _L, t _s, t _c(90), R _v) as well as physico-mechanical properties (tensile strength, modulus at 300 elongation—M ₃₀₀, tensibility).     

Thermal and microstructural characterization of compatibilized polystyrene/natural fillers composites

Composites of polystyrene (PS) with cellulose microfibres and oat particles, obtained by melt mixing, were examined. The compatibilization of the composites was carried out by addition of maleic anhydride-functionalized copolymers (SEBS-g-MA, PS-co-MA) and poly(ethylene glycol) to improve the fibre–matrix interfacial interactions. The plain components and their composites were characterised by FT-IR, DSC, TGA, SEM microscopy and mechanical tests. The properties of the various systems were analysed as a function of both fibre and compatibilizer amount. The compatibilized PS composites showed enhanced fibre dispersion and interfacial adhesion as a consequence of chemical interactions between the anhydride groups on the polymer chains and the hydroxyl groups on the fibres, as demonstrated by FT-IR spectroscopy. DSC analysis pointed out a neat increase of T _g of composites on addition of SEBS-g-MA, as compared to PS-co-MA. The thermal stability of composites was also influenced by the type and amount of fibres, as well as by the structure and concentration of compatibilizer. The effect of the reactive copolymers on the composites properties was accounted for on the basis of the polymer–polymer miscibility and chemical interactions at the matrix/filler interface.     

Preparation and characterization of melt‐compounded polyethylene/vermiculite nanocomposites

Polyethylene (PE)‐layered vermiculite (VMT) nanocomposites were fabricated via direct melt compounding in a twin‐screw extruder followed by injection molding. Exfoliated PE/VMT nanocomposites were readily prepared via in situ melt mixing of maleic anhydride modified VMT with PE. Maleic anhydride acts as either the intercalation agent for VMT or as a compatibilizer for the PE and VMT phases. X‐ray diffraction and transmission electron microscopic observations revealed the formation of exfoliated PE/VMT nanocomposites. The experimental results showed that the storage modulus and strength of nanocomposites tend to increase with an increasing VMT content. Nearly 25.35% increment in the tensile strength and 50% increment in the storage modulus were achieved by incorporating 4 wt % VMT into PE. The thermal properties of the nanocomposites were investigated by dynamic mechanical analysis and differential scanning calorimetry. The glass‐transition temperature of PE/VMT nanocomposites appeared to increase upon the introduction of VMT into the PE matrix. The effects of maleic anhydride addition on the formation of the PE/VMT nanocomposites are discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1476–1484, 2003     

Preparation of high thermal conductive aluminum nitride/cyanate ester nanocomposite using a new macromolecular coupling agent

Novel glycidyl methacrylate–butyl acrylate–maleic anhydride (GBM) terpolymers with different molecular weights were synthesized by radical polymerization and characterized using fourier transform infrared, nuclear magnetic resonance (¹H‐NMR and ¹³ C‐NMR), and gel permeation chromatography. Each GBM terpolymer was used to modify aluminum nitride (AlN), and the modified AlN, coded as AlN(GBM), was added to 2,2′‐bis(4‐cyanatophenyl)isopropylidene (CE) resin for preparing composites. Composites based on original AlN or γ‐(2,3‐epoxypropoxy)propyltrimethoxysilane‐modified AlN (AlN(K)) were also prepared for comparison. Although GBM and γ‐(2,3‐epoxypropoxy)propyltrimethoxysilane have similar reactive groups, the results indicate that GBM shows more attractive integrated advantages, reflected by the fact that CE/AlN(GBM) composites have better thermal stability, higher thermal conductivity, and higher glass transition temperature than those of CE/AlN(K). These properties result from better dispersion of fillers, improved interfacial adhesion between fillers and CE resin, and increased cross‐linking density. This study demonstrates that the nature of the coupling agents is an important factor to develop high performance composites for cutting‐edge industries. Copyright © 2011 John Wiley & Sons, Ltd.     

Blends of styrene/maleic anhydride copolymers with polymethacrylates

The phase behavior of a series of styrene/maleic anhydride (SMA) copolymers with various polyacrylate and polymethacrylate homopolymers has been investigated using various techniques. None of the polyacrylates are miscible with SMA copolymers. Poly (methyl methacrylate) (PMMA) poly(ethyl methacrylate) (PEMA) and poly(n-propyl methacrylate) (PnPMA), are miscible with these copolymers over a certain range of maleic anhydride contents; whereas, the higher methacrylates apparently have no region of miscibility. For PEMA and PnPMA, the miscibility windows extend through 0% MA; hence, polystyrene is miscible with these polymethacrylates although the lower critical solution temperature is quite low. The exothermic heat of mixing styrene and ester analogs found here supports the observed miscibility of polystyrene with ethyl, n-propyl, and cyclohexyl (reported elsewhere) methacrylates. Lattice fluid interaction parameters for styrene-methacrylate obtained from the cloud points of these blends agree quite well with the Flory—Huggins parameters obtained from copolymer miscibility windows.     

Peroxide-Induced Synthesis of Maleic Anhydride-Grafted Poly(butylene succinate) and Its Compatibilizing Effect on Poly(butylene succinate)/Pistachio Shell Flour Composites

Framing the Circular Bioeconomy, the use of reactive compatibilizers was applied in order to increase the interfacial adhesion and, hence, the physical properties and applications of green composites based on biopolymers and food waste derived lignocellulosic fillers. In this study, poly(butylene succinate) grafted with maleic anhydride (PBS-g-MAH) was successfully synthetized by a reactive melt-mixing process using poly(butylene succinate) (PBS) and maleic anhydride (MAH) that was induced with dicumyl peroxide (DCP) as a radical initiator and based on the formation of macroradicals derived from the hydrogen abstraction of the biopolymer backbone. Then, PBS-g-MAH was used as reactive compatibilizer for PBS filled with different contents of pistachio shell flour (PSF) during melt extrusion. As confirmed by Fourier transform infrared (FTIR), PBS-g-MAH acted as a bridge between the two composite phases since it was readily soluble in PBS and could successfully form new esters by reaction of its multiple MAH groups with the hydroxyl (–OH) groups present in cellulose or lignin of PSF and the end ones in PBS. The resultant compatibilized green composites were, thereafter, shaped by injection molding into 4-mm thick pieces with a wood-like color. Results showed significant increases in the mechanical and thermomechanical rigidity and hardness, meanwhile variations on the thermal stability were negligible. The enhancement observed was related to the good dispersion and the improved filler-matrix interfacial interactions achieved by PBS-g-MAH and also to the PSF nucleating effect that increased the PBS’s crystallinity. Furthermore, water uptake of the pieces progressively increased as a function of the filler content, whereas the disintegration in controlled compost soil was limited due to their large thickness.     

Triple shape memory effect of foamed natural Eucommia ulmoides gum/high‐density polyethylene composites

This paper proposes a new technique for the preparation of foamed Eucommia ulmoides gum (EUG)/high‐density polyethylene (HDPE) shape memory composites and establishes the relationship between structures and properties in foamed shape memory composites. Eucommia ulmoides gum/HDPE shape memory composites are designed to memorize 2 temporary shapes by exploiting the different melting points of the 2 phases; the triple shape memory effect in the composites is investigated via mechanical measurements, thermal analysis, and shape memory behavior analysis. The results show that HDPE phase enables the composites to effectively memorize the first temporary shape and EUG phase contributes the second temporary shape. When the ratios of EUG and HDPE were 80/20 and 70/ 30, the composite exhibited satisfactory shape memory behavior with favorable shape fixity ratio and shape recovery ratio, in addition to excellent mechanical properties (tensile strength of 15 MPa, tear strength above 51 KN/m, and foam porosity of about 11%).     

Mechanical Properties and Morphology of Melt-mixed PA6/SWNT Composites: Effect of Reactive Coupling

An interfacial reaction during melt mixing of maleic anhydride copolymer (SMA) encapsulated single wall carbon nanotubes (SWNT) and polyamide 6 (PA6) was used in order to disperse SWNT homogeneously and to enhance interfacial adhesion. The intended reactive coupling between PA6 and SMA was evident from IR spectroscopy. Nanocomposites with SMA encapsulated SWNT showed increased elongation at break as compared to PA6/SWNT composites. SEM investigation of tensile fractured surfaces of PA6/SWNT+SMA composites indicated enhanced interfacial adhesion between PA6 and SMA modified SWNT.     

Combined effects of clay modifications and compatibilizers on the formation and physical properties of melt‐mixed polypropylene/clay nanocomposites

The melt mixing technique was used to prepare various polypropylene (PP)‐based (nano)composites. Two commercial organoclays (denoted 20A and 30B) served as the fillers for the PP matrix, and two different maleated (so‐called) compatibilizers (denoted PP‐MA and SMA) were employed as the third component. The results from X‐ray diffraction (XRD) and transmission electron microscope (TEM) experiments revealed that 190 °C was an adequate temperature for preparing the nanocomposites. Nanocomposites were achieved only if specific pairs of organoclay and compatibilizer were simultaneously incorporated in the PP matrix. For example, PP/20A(5 wt %)/PP‐MA(10 wt %) and PP/30B(5 wt %)/SMA(5 wt %) composites exhibited nanoscaled dispersion of 20A or 30B in the PP matrix. Differential scanning calorimetry (DSC) results indicated that the organoclays served as nucleation agents for the PP matrix. Generally, their nucleation effectiveness increased with the addition of compatibilizers. The thermal stability enhancement of PP after adding 20A was confirmed with thermogravimetric analysis (TGA). The enhancement became more evident as a suitable compatibilizer was further added. However, for the 30B‐included composites, thermal stability enhancement was not evident. The dynamic mechanical properties (i.e., storage modulus and loss modulus) of PP increased as the nanocomposites were formed; the properties increment corresponded to the organoclay dispersion status in the matrix. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4139–4150, 2004     

Synthesis of natural rubber-g-maleic anhydride and its use as a compatibilizer in natural rubber/short nylon fiber composites

Natural rubber grafted maleic anhydride (NR-g-MAH) was synthesized by mixing maleic anhydride (MAH) and natural rubber (NR) in solid state in a torque rheometer using dicumyl peroxide (DCP) as initiator. Then the self-prepared NR-g-MAH was used as a compatibilizer in the natural rubber/short nylon fiber composites. Both the functionalization of NR with MAH and the reaction between the modified rubber and the nylon fiber were confirmed by Fourier transform infrared spectroscopy (FTIR). Composites with different nylon short fiber loadings (0, 5, 10, 15 and 20 phr) were compounded on a two-roll mill, and the effects of the NR-g-MAH on the tensile and thermal properties, fiber-rubber interaction, as well as the morphology of the natural rubber/short nylon fiber composites were investigated. At equal fiber loading, the NR-g-MAH compatibilized NR/short nylon fiber composites showed improved tensile properties, especially the tensile modulus at 100% strain which was about 1.5 times that of the corresponding un-compatibilized ones. The equilibrium swelling tests proved that the incorporation of NR-g-MAH increased the interaction between the nylon fibers and the NR matrix. The crosslink density measured with NMR techniques showed that the NR-g-MAH compatiblized composites had lower total crosslink density. The glass transition temperatures of the compatibilized composites were about 1 K higher than that of the corresponding un-compabilized ones. Morphology analysis of the NR/short nylon fiber composites confirmed NR-g-MAH improved interfacial bonding between the NR matrix and the nylon fibers. All these results signified that the NR-g-MAH could act as a good compatilizer of NR/short nylon fiber composites and had a potential for wide use considering its easy to be prepared and compounded with the composites.     

Mechanical and thermal investigation of thermoplastic nanocomposite films fabricated using micro- and nano-sized fillers from recycled cotton T-shirts

The thermal and mechanical performance of composites with nano-sized cotton fillers embedded in low-density polyethylene (LDPE) is investigated. Microfibrillated cotton was prepared by microgrinding mechanical treatment of pulverized cotton (pCot) derived from waste T-shirts, resulting in nano-sized fibrils of the cellulose that retain high crystallinity. Film composites of LDPE with pCot before and after microgrinding were fabricated through melt extrusion and the effect of filler size on mechanical, thermal and morphological properties of the composite was investigated. Compounding microfibrillated cotton with LDPE resulted in well-dispersed nanocomposites with no discoloration after 10 min of melt extrusion at 170 °C. At concentrations up to 10 % by weight, the composites showed increased modulus, increased tensile strength and a slight decrease in elongation to break. Further improvement in the dispersion and mechanical properties of the cotton-based fillers was realized by the use of LDPE powder instead of polymer pellets fed to the extruder. This research demonstrates the processing and applicability of the use of recycled cotton-based nano-sized fillers in melt-processing.     

Kapok/cotton fabric–polypropylene composites

Kapok/cotton fabric has been used as reinforcement for conventional polypropylene and maleic anhydride grafted polypropylene resins. Treating the reinforcement with acetic anhydride and sodium hydroxide has modified the fabric (fibres). Thermal and mechanical properties of the composites were investigated. Results show that fibre modification gives a significant improvement to the thermal properties of the plant fibres, whereas tests on the mechanical properties of the composites showed poor tensile strength. Mercerisation and weathering were found to impart toughness to the materials, with acetylation showing slightly less rigidity compared to other treatments on either the fibre or composites. The modified polypropylene improved the tensile modulus and had the least toughness of the kapok/cotton reinforced composites. MAiPP reinforced with the plant fibres gave better flexural strength and the same flexural modulus at lower fibre content compared with glass fibre reinforced MAiPP.     

Design of aluminum trihydroxide and P‐N core‐shell structures and their synergistic effects on halogen‐free flame‐retardant polyethylene composites

In order to improve the performance of inorganic/organic composites, aluminum trihydroxide (ATH) core composites with a styrene‐ethylene‐butadiene‐styrene block copolymer grafted with maleic anhydride (MAH‐g‐SEBS) shell phase, and P‐N flame retardant as a synergistic agent, were prepared through an interface design. The effects of polyethylene glycol (PEG) content on the interfacial interaction, flame retardancy, thermal properties, and mechanical properties of high‐density polyethylene (HDPE)/ATH composites were investigated by small angle X‐ray diffraction, rotational rheometer, limiting oxygen index, thermogravimetric analysis (TGA), and tensile testing. The ATH synergistic effects of P‐N flame‐retardant improved the combustion performance of HDPE/ATH/PEG(3%)/MAH‐g‐SEBS/P‐N (abbreviated as HDPE/MH3/M‐g‐S/P‐N) composite by forming more carbon layer, increased the elongation at break from 21% to 558% compared to HDPE/ATH, and increased the interface thickness from 0.447 to 0.891 nm. SEM results support the compatibility of ATH with HDPE increased and the interfacial effect was enhanced. TGA showed the maximum decomposition temperature of the two stages and the yield of the residue at high temperature increased first and then decreased with the increase of PEG content. Rheological behavior showed the storage modulus, complex viscosity, and the relaxation time initially increased and then decreased with the increase of PEG content indicating PEG, M‐g‐S, and ATH powder gradually formed a partial coating, then a full coating, and finally an over‐coated core‐shell structured model.     

Bioengineering functional copolymers. III. Synthesis of biocompatible poly[(N‐isopropylacrylamide‐co‐maleic anhydride)‐g‐poly(ethylene oxide)]/poly(ethylene imine) macrocomplexes and their thermostabilization effect on the activity of the enzyme penicillin G acylase

Stimuli‐responsive poly[(N‐isopropylacrylamide‐co‐maleic anhydride)‐g‐poly(ethylene oxide)]/poly(ethylene imine) macrobranched macrocomplexes were synthesized by (1) the radical copolymerization of N‐isopropylacrylamide and maleic anhydride with α,α′‐azobisisobutyronitrile as an initiator in 1,4‐dioxane at 65 °C under a nitrogen atmosphere, (2) the polyesterification (grafting) of prepared poly(N‐isopropylacrylamide‐co‐maleic anhydride) containing less than 20 mol % anhydride units with α‐hydroxy‐ω‐methoxy‐poly(ethylene oxide)s having different number‐average molecular weights (M_n = 4000, 10,000, or 20,000), and (3) the incorporation of macrobranched copolymers with poly(ethylene imine) (M_n = 60,000). The composition and structure of the synthesized copolymer systems were determined by Fourier transform infrared, ¹H and ¹³C NMR spectroscopy, and chemical and elemental analyses. The important properties of the copolymer systems (e.g., the viscosity, thermal and pH sensitivities, and lower critical solution temperature behavior) changed with increases in the molecular weight, composition, and length of the macrobranched hydrophobic domains. These copolymers with reactive anhydride and carboxylic groups were used for the stabilization of penicillin G acylase (PGA). The conjugation of the enzyme with the copolymers significantly increased the thermal stability of PGA (three times at 45 °C and two times at 65 °C). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1580–1593, 2003