Reactive Melt Mixing Research Articles

Performance Enhancement of Biopolyester Blends by Reactive Compatibilization with Maleic Anhydride-Grafted Poly(butylene succinate-co-adipate).

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a very promising biodegradable copolyester of high interest in food packaging. Its inherent brittleness and narrow processing window make it necessary to blend it with flexible biopolyesters, such as poly(butylene succinate-co-adipate) (PBSA). However, the resultant biopolyester blends are thermodynamically immiscible, which impairs their performance and limits their applications. This study is the first to explore the use of poly(butylene succinate-co-adipate) grafted with maleic anhydride (PBS-g-MAH) as a novel reactive additive to compatibilize PHBV/PBSA blends. The compatibilizer was prepared by a reactive melt-mixing process of PBSA and maleic anhydride (MAH) using dicumyl peroxide (DCP) as an organic radical initiator, achieving a grafting degree (Gd) of 5.4%. Biopolyester blend films were thereafter prepared via cast extrusion and their morphological, thermal, mechanical, and barrier properties were characterized. Compatibilization by PBSA-g-MAH was confirmed by observing an improved phase interaction and lower dispersed domain sizes in the blends with 15 wt% PBSA. These compatibilized PHBV/PBSA blends were thermally stable up to 285 °C, showed enhanced ductility and toughness, as well as providing an improved barrier against water and limonene vapors and oxygen. These findings suggest that the use of MAH-grafted biopolyesters can represent an effective strategy to improve the properties of biopolyester blends and open up new opportunities for the application of PHBV-based formulations for food packaging.

Post-polymerization modification of polypropylene with different functional groups utilizing non-catalytic C–H insertion of sulfonyl azide

This study presents a comprehensive investigation into the preparation of functionalized polypropylene (PP) with different functional groups, such as amino-, hydroxyl-, acetamido-, and carboxyl-groups, utilizing efficient C–H insertion capability of sulfonyl azide (SA) compounds with the functional groups. The reactive melt mixing of PP and the SA compounds was performed at temperatures determined by the decomposition temperatures of the SA groups, followed by purification processes to remove unreacted SA compounds, confirming the establishment of stable covalent linkages between the SA compounds and PP chains. Grafting efficiency (GE) values were determined using FT-IR spectroscopy, showcasing efficient grafting of the SA compounds onto PP chains with GE values ranging from 60 % to 70 %. Remarkably, SA compound with carboxyl functional group exhibited an exceptionally high GE value of ∼90 %, likely attributed to its electron-withdrawing carbonyl group. XRD analyses, thermal analyses, morphological analyses of cryogenically fractured modified PPs and mechanical property analyses revealed successful incorporation of SA compounds into PP chains with relatively low sensitivity of the crystal structure of the modified PPs to the incorporated SA compounds. Hydrophilicity assessments revealed improved paint adhesion capabilities of the modified PP surfaces, highlighting the potential for the tailored surface modification strategies to enhance material characteristics.

Enhanced mechanical properties of poly(butylene succinate)/silk sericin composite monofilaments with silane coupling agent KH570

Biodegradable Poly (butylene succinate) (PBS) composites with natural polymers have been widely developed, the compatibility of PBS and natural polymers is often the first consideration in terms of performance. In this work, PBS/silk sericin composite monofilaments (content of silk sericin is 6 wt%) with γ-methacryloxypropyltrimethoxysilane (KH570) as the coupling agent were fabricated by reactive melt-mixing, spinning, and stretching. The effect of KH570 content (1–3 wt%) on the morphology, mechanical property and biodegradation was studied. The reaction between the hydroxyl groups of silk sericin and -Si-OH of KH570 was analyzed by Fourier transform infrared spectroscopy. The cross-section morphology of the monofilaments obtained from SEM and EDS images indicates that the dispersion of silk sericin is improved with the increase of KH570 content. Compared with unmodified composite monofilaments, the composite monofilament with 2 wt% KH 570 shows the best mechanical performance (102% and 80% improvement in tensile strength and elongation at break respectively). The incorporation of silk sericin, which possesses skin-friendly properties, imparts composite monofilaments with advantages in the fields of clothing, headgear, shoe uppers and other related applications. Otherwise, the silk sericin can enhance the biodegradability velocity of PBS/silk sericin composite monofilaments. And the weight loss of the composite monofilaments buried in soil can be adjusted by the synergistic effect of silk sericin and KH570.

Medical grade polyamide 12 silver nanoparticle filaments fabricated with in-situ reactive reduction melt-extrusion: rheological, thermomechanical, and bactericidal performance in MEX 3D printing

The development of bioactive, multi-functional, and cost-effective nanocomposite filaments for additive manufacturing (AM) is pivotal for the evolution of biomedical and healthcare sectors. Herein, an industrially scalable process is reported, to produce medical grade PA12/AgNP nanocomposites, through in-situ reactive melt-mixing, occurring within the filament extruder. Bactericidal elemental nanoparticles (Ag0) were formed by silver ions (Ag+) reducing from the Silver Nitrate (Ag2NO3) precursor, which was suitably added to the polymer melt. Polyvinyl Alcohol (PVA) was deployed in the compound melt, as a reducing macromolecular agent. The produced nanocomposite filaments were utilized to fabricate samples with Material Extrusion (MEX) AM. A total of sixteen (16) different tests were conducted on filaments and 3D-printed samples to assess their mechanical, rheological, thermal, and antibacterial characteristics, in accordance with international standards. The nanocomposites exhibited a significant mechanical reinforcement of up to 50% compared to PA12. Additionally, the Ag-based nanocomposites demonstrated remarkable antimicrobial behavior in the presence of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) microbes.

Polyethylene glycol and polyvinylpyrrolidone reduction agents for medical grade polyamide 12/silver nanocomposites development for material extrusion 3D printing: Rheological, thermomechanical, and biocidal performance

Nanocomposites for Additive Manufacturing (AM) featuring enhanced mechanical properties and antibacterial performance are desirable in the medical and culinary fields. Silver nitrate was introduced as a reinforcement and antibacterial agent in a medical-grade polyamide 12 (PA12) for the preparation of PA12/Ag nanocomposites for the material extrusion (MEX) AM method, with a reactive melt mixing process. Polyethylene glycol and polyvinylpyrrolidone were introduced into the mixture as reduction agents. The chemical reaction occurred during the filament extrusion. Samples compatible with the corresponding international standards were 3D printed and sixteen tests were performed to characterize the nanocomposites for their rheological, thermal, mechanical, and antibacterial properties. The mechanical reinforcement reached 26% in the tensile test, 24.2% in the compression test, and 26.1% in the flexural test, with similar improvement in the stiffness of the material in all tests. These results were achieved by the PA12/ 5.0% AgNO3 / 2.5% PEG nanocomposite. The biocidal activity of Ag was induced in the nanocomposites, as the tests against Escherichia coli and Staphylococcus aureus showed. The process followed can be easily scaled up for industrial use.

Lid Films of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/Microfibrillated Cellulose Composites for Fatty Food Preservation.

The present work evaluates the food packaging performance of previously developed films of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) reinforced with atomized microfibrillated cellulose (MFC) compatibilized by a reactive melt-mixing process. To this end, the novel green composite films were originally applied herein as lids in aluminum trays to preserve two dissimilar types of fatty foods, namely minced pork meat and sunflower oil. Results indicated that the PHBV/MFC films effectively preserved the physicochemical and microbiological quality of pork meat for one week of storage at 5 °C. In particular, the compatibilized green composite lid film yielded the lowest weight loss and highest oxidative stability, showing values of 0.935% and 0.78 malonaldehyde (MDA)/kg. Moreover, none of the packaged meat samples exceeded the acceptable Total Aerobial Count (TAC) level of 5 logs colony-forming units (CFU)/g due to the improved barrier properties of the lids. Furthermore, the green composite films successfully prevented sunflower oil oxidation in accelerated oxidative storage conditions for 21 days. Similarly, the compatibilized PHBV/MFC lid film led to the lowest peroxide value (PV) and conjugated diene and triene contents, with respective values of 19.5 meq O2/kg and 2.50 and 1.44 g/100 mL. Finally, the migration of the newly developed PHBV-based films was assessed using two food simulants, proving to be safe since their overall migration levels were in the 1-3 mg/dm2 range and, thus, below the maximum level established by legislation.

Evaluation of poly(lactic acid)/ and poly(lactic-co-glycolic acid)/ poly(ethylene adipate) copolymers for the preparation of paclitaxel loaded drug nanoparticles

The present study evaluates the use of novel poly(lactic acid)/poly(ethylene adipate) (PLA-PEAd) and poly(lactic-co-glycolic acid)/poly(ethylene adipate) (PLGA-PEAd) copolymers for the preparation of paclitaxel (PTX) loaded nanoparticles (NPs). Specifically, four copolymers, namely PLA-PEAd and PLGA-PEAd at 90/10 and 75/25 w/w ratio, were prepared via reactive melt mixing, and their successful synthesis was verified by proton nuclear magnetic resonance (1H NMR and 13C NMR) and FTIR analysis. Then, the enzymic hydrolysis and cytotoxicity characteristics of them were comprehensively assessed. The results confirmed that all synthesized copolymers can be enzymatically hydrolyzed (i.e., are biodegradable) with low cytotoxicity, and hence can be used as suitable drug matrix/carriers. In the next step, the newly synthesized copolymers were used to prepare PTX-loaded NPs via o/w emulsification/solvent evaporation method. The size of the PTX-loaded NPs varied from 250 to 490 nm, depending on the polyester used, while X-ray diffraction analysis revealed that the drug was amorphously dispersed in all cases. Scanning electron microscopy showed the formation of spherical NPs with smooth surfaces, while good drug loading and encapsulation efficiency values were obtained in all cases. Finally, the in vitro dissolution analysis of all prepared PTX-loaded NPs showed biphasic drug dissolution profiles in all cases, while the use of PEAd resulted in the formation of NP having highly tunable dissolution properties.

Enhancing Toughness of PLA/ZrP Nanocomposite through Reactive Melt-Mixing by Ethylene-Methyl Acrylate-Glycidyl Methacrylate Copolymer.

The nanofiller zirconium phosphate (ZrP) was mixed into poly(lactic acid) (PLA) to ameliorate its thermal stability. The elastomer ethylene-methyl acrylate-glycidyl methacrylate copolymer (E-MA-GMA) was introduced into the PLA/ZrP nanocomposite through melt-mixing to improve its toughness and obtain a super-tough PLA/ZrP/E-MA-GMA nanocomposite. The impact strength of the PLA/ZrP/E-MA-GMA nanocomposite, with a composition ratio of 72/3/25, was improved to 71.5 kJ/m2, about 25 times greater than the impact strength of pure PLA. The dynamic mechanical analysis (DMA) confirmed that E-MA-GMA has excellent compatibility with the matrix of PLA. A typical core–shell structure that can cause massive shear-yielding deformation was characterized by transmission electron microscopy (TEM), which gave the nanocomposite excellent toughness.

Preparation of environment‐friendly hydrophilic rubber from natural rubber grafted with sodium acrylate by reactive melt mixing

AbstractIn this research, we present an easy way to prepare environment‐friendly hydrophilic rubbers derived from natural rubber (NR) grafted with sodium acrylate (NaAA) through reactive blending using an internal mixer operated at a rotor speed of 80 rpm and 150°C. The key parameters affecting the grafting efficiency of NR‐g‐NaAA were investigated in terms of the fill factor (FF) of the chamber, mixing time, and NaAA content. Lastly, the grafted sample (with a suitable grafting efficiency) was crosslinked using peroxide curing to produce X(NR‐g‐NaAA) as a hydrophilic NR sample. Results showed that grafting efficiency of the NR‐g‐NaAA samples tended to decrease with increasing FF and NaAA contents owing to the higher chain‐scission reaction rather than the free‐radical generation on the NR molecules in the mastication step, while the optimal mixing time was only 4 min. The remarkable improvement in the hydrophilicity of NR by grafting with NaAA was established via the presence of C = O vibration of the ionized carboxylate group (–COO−) of NaAA located at 1559 cm−1. Increasing the grafting efficiency up to 69% resulted in a marked decrease in the water contact angle from 103° to 72° and enhanced the water swelling of the X(NR‐g‐NaAA) sample.

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.

Three-Dimensional Printed Antimicrobial Objects of Polylactic Acid (PLA)-Silver Nanoparticle Nanocomposite Filaments Produced by an In-Situ Reduction Reactive Melt Mixing Process.

In this study, an industrially scalable method is reported for the fabrication of polylactic acid (PLA)/silver nanoparticle (AgNP) nanocomposite filaments by an in-situ reduction reactive melt mixing method. The PLA/AgNP nanocomposite filaments have been produced initially reducing silver ions (Ag+) arising from silver nitrate (AgNO3) precursor mixed in the polymer melt to elemental silver (Ag0) nanoparticles, utilizing polyethylene glycol (PEG) or polyvinyl pyrrolidone (PVP), respectively, as macromolecular blend compound reducing agents. PEG and PVP were added at various concentrations, to the PLA matrix. The PLA/AgNP filaments have been used to manufacture 3D printed antimicrobial (AM) parts by Fused Filament Fabrication (FFF). The 3D printed PLA/AgNP parts exhibited significant AM properties examined by the reduction in Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria viability (%) experiments at 30, 60, and 120 min duration of contact (p < 0.05; p-value (p): probability). It could be envisaged that the 3D printed parts manufactured and tested herein mimic nature’s mechanism against bacteria and in terms of antimicrobial properties, contact angle for their anti-adhesive behavior and mechanical properties could create new avenues for the next generation of low-cost and on-demand additive manufacturing produced personal protective equipment (PPE) as well as healthcare and nosocomial antimicrobial equipment.

SEBS-Grafted Itaconic Acid as Compatibilizer for Elastomer Nanocomposites Based on BaTiO3 Particles

Itaconic acid (IA) is an organic acid produced by the fermentation of sugars with aspergillus. It has been identified as one of the top 12 building-block chemicals. Here, we report the use of IA as a possible substitute to petroleum-based compatibilizers in polymer composite. We applied this study to thermoplastic elastomers based on styrene copolymers, since they are commonly used in blends and composites. Poly(styrene-b-ethylene-butylene-b-styrene) (SEBS) was grafted with 2.6 wt.% of itaconic acid (SEBS-g-IA) prepared by a reactive melt-mixing process, and was subsequently used to prepare composites filled with BaTiO3.). IA was successfully grafted as demonstrated by FTIR and XRD. SEBS-g-IA composites presented better mechanical properties, achieving an increase of Young modulus up to 80% compared with the neat polymer. This was ascribed to better dispersion and compatibility with the filler. Additionally, SEBS-g-IA showed increased dielectric permittivity, i.e., showed increased polarity, which indicates that it could potentially be used as a modifier for specialized polymers.

Reactive melt processing of poly (L-lactide) in the presence of thermoplastic polyurethane and carboxylated carbon nanotubes

In this study, two types of polymeric nanocomposite blends based on poly(l-lactide) (PLLA) and a thermoplastic polyurethane were prepared by reactive and non-reactive melt mixing. Multiwalled carbon nanotubes (MWCNTs) participated in reactive melt mixing and changed in both cases the morphology of blends. Melt rheology was used to study the influence of reactive melt mixing and localization of MWCNTs in terms of melt viscoelastic properties and relaxation time spectrum. Two relaxation times were observed for both types of blends due to reptation and stress release mechanism, although blends prepared by reactive melt mixing showed another relaxation mechanism associated with the generated interphase. Solid-state viscoelasticity determined by dynamical mechanical analysis showed significant influences of both MWCNTs and reactive melt mixing on storage modulus of the blends. Thermogravimetric analysis showed several degradation steps for polymer blends that contrast with the single step determined for both pure PLLA and PLLA nanocomposites.

Reactive Melt Mixing of Poly(3-Hydroxybutyrate)/Rice Husk Flour Composites with Purified Biosustainably Produced Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate).

Novel green composites based on commercial poly(3-hydroxybutyrate) (PHB) filled with 10 wt % rice husk flour (RHF) were melt-compounded in a mini-mixer unit using triglycidyl isocyanurate (TGIC) as compatibilizer and dicumyl peroxide (DCP) as initiator. Purified poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) produced by mixed bacterial cultures derived from fruit pulp waste was then incorporated into the green composite in contents in the 5–50 wt % range. Films for testing were obtained thereafter by thermo-compression and characterized. Results showed that the incorporation of up to 20 wt % of biowaste derived PHBV yielded green composite films with a high contact transparency, relatively low crystallinity, high thermal stability, improved mechanical ductility, and medium barrier performance to water vapor and aroma. This study puts forth the potential use of purified biosustainably produced PHBV as a cost-effective additive to develop more affordable and waste valorized food packaging articles.

Fabricating dual-responsive shape memory PVA-based composites via reactive melt-mixing by skillfully utilizing excellent flowability and crosslinking heat of polyethylene

Poly(vinyl alcohol) (PVA) based dual-stimuli responsive shape memory composites were fabricated via a feasible reactive melt mixing with certain content of polyethylene (PE) and crosslinker dicumyl peroxide (DCP). It is found that PE plays many important roles in this method. Firstly, the melting processability of PVA can be improved markedly by skillfully utilizing the excellent flowability and crosslinking heat of PE. Secondly, the PVA composites achieve excellent water/heat dual-induced shape memory property by utilizing PE as fixing domain and heat responsive switching domain and utilizing PVA as water responsive switching domain meanwhile. The fixing ratio is nearly 100% and recovery ratio can reach 90% for both water and heat responsive shape memory. This artful fabricating method achieved the aim of improving the melting processability of PVA and endowing the composites dual-responsive shape memory property simultaneously only by utilizing PE, which is interesting and promising for the development of PVA in the industry application. It shows considerable prospect for PVA composites and their industry application.

Rigid amorphous phase and constrained polymer chains in poly(L‐lactide) nanocomposites with carboxylated carbon nanotubes prepared via reactive melt mixing

Evaluation of constrained polymer chains and the glass transition behavior of the nanocomposite constituted by poly(L‐lactide) (PLLA) and functionalized carbon nanotubes (f‐CNTs) have been carried out. To control thermal degradation, nanocomposites were prepared via reactive melt mixing taking advantage of the capacity of carboxylic groups of both PLLA and f‐CNTs to participate in chain extension reactions. At low f‐CNT content (e.g., 0.2 and 0.5 wt%), a good dispersion of f‐CNTs was observed due to scarce bonds established between both components (i.e., the polymer matrix and the nanofiller), whereas at higher f‐CNT content (e.g., 1 wt%), a greater number of epoxy groups of the chain extender were bonded to carboxyl groups of f‐CNTs, giving rise to a highly significant crosslinking of CNT and a lower molecular weight of PLLA. Crystallinity, glass transition temperature and both the rigid polymer chains and constrained polymer chains were influenced by the dispersion state of f‐CNTs after reactive melt mixing and the thermal history (e.g., cooling rate form the melt) of samples. For evaluation of interphases between poly(lactic acid) and f‐CNTs, a simple method was developed for the considered tube‐like nanoparticles. Specifically, thicknesses of the generated interphases were calculated from DMA experiments. POLYM. COMPOS., 39:E1280–E1293, 2018. © 2018 Society of Plastics Engineers

Study of Na-Montmorillonite–Polyamide Fiber/Polypropylene Hybrid Composite Prepared by Reactive Melt Mixing

Hybrid composites of polypropylene (PP)/sodium montmorillonite (Na-MMT)/short polyamide fibers (PAfs) were prepared by reactive melt mixing in a Brabender plastograph. To enhance filler interactions within polypropylene, a functionalizing agent (FA) and a coupling agent were added to the Na-MMT and PAfs, respectively. An organic peroxide/sulfur mixture and tetramethylthiuram disulfide as an activator for sulfur were used to functionalize Na-MMT; on the other hand, the PAfs surface was treated using stearic acid. The aim of this study is to investigate how the morphology and the structural properties of 3, 5, and 7 wt% recycled functionalized sodium montmorillonite nanocomposites (f-Na-MMT) are affected by the presence of 5 wt% treated short polyamide fibers (t-PAfs). According to the obtained results, 5 wt% recycled f-Na-MMT/5 wt% t-PAfs/PP hybrid composite showed Na-MMT layers exfoliation. The nucleating effect of f-Na-MMT and t-PAfs was indicated by the differential scanning calorimetry (DSC) measurements. Morphological analysis of the hybrid composites was performed using scanning electron microscope (SEM) and optical polarized microscopy (POM), showing a good dispersion of the fibers with an interesting interfacial adhesion between the PP and t-PAfs phases. Hybrid composites of PP/f-Na-MMT/t-PAfs are considered for automotive industry.

One-step method to prepare starch-based superabsorbent polymer for slow release of fertilizer

Here we report the use of a one-step process of reactive melt mixing to prepare starch-based superabsorbent polymers (SBSAPs) for the slow release of urea as a fertilizer. A modified twin-rotor mixer, with improved sealing to establish an oxygen-free environment, was used to study the chemical and physical reactions during the melt-processing through monitoring the temperature and torque. The effects of the initiator (ceric ammonium nitrate, or CAN), crosslinker (N,N′-methylene-bisacrylamide, or N,N′-MBA) and saponification agent (NaOH) under different reaction conditions (time, temperature, and shear intensity) were systematically studied. Also investigated was the effect of starch with different amylose content. Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) confirmed that using this simple technique, SBSAPs were successfully prepared from either high-amylopectin starch (waxy corn starch) or high-amylose starch (Gelose 50) grafted with AM and crosslinked by N,N′-MBA. Gel strength was evaluated by rheometry, which revealed a significant increase in storage modulus (G′) obtained in the crosslinked high-amylose SBSAP gels. Also, scanning electron microscopy (SEM) images showed a more sophisticated structural network with a smaller pore size in the crosslinked high-amylose gels. Urea as a fertilizer was embedded in the SBSAP gel network, and this network controlled the urea release in water. The release rate of urea depended on the gel strength, gel microstructure and water absorption capacity (WAC) of SAP, which was affected by the reaction conditions and degree of saponification.

Double bond-functionalized POSS: dispersion and crosslinking in polyethylene-based hybrid obtained by reactive processing

Polyethylene-based organic inorganic hybrids were prepared by one-step reactive melt mixing using a mono-functionalized nanofiller, i.e., allyl-heptaisobutyl-substituted polyhedral oligomeric silsesquioxane (1POSS) and a multi-functionalized octavinyl polyhedral oligomeric silsesquioxane (8POSS). The hybrids were also prepared in dicumyl peroxide (DCP) presence and morphological, spectroscopical and calorimetric analysis were carried out. Moreover, rheological measurement and Sohxlet extraction were performed on investigated samples. It was inferred that double bonds of POSS functional groups were triggered by radicals coming from the peroxide decomposition or from the degradation reactions occurring during preparation. The type of the functional groups (mono- or multi-reactive) of the POSS is a leading factor, along with radicals content in the systems, in the formation of a polymeric network. In particular, the presence of multi-reactive groups in 8POSS molecules results in a successful POSS grafting/crosslinking in the polymeric backbone: the covalent bonds formation between nanofillers and matrix during processing improves POSS dispersion within the polyolefin matrix and leads to a network structure formation.

POSS Grafting on Polyethylene and Maleic Anhydride‐Grafted Polyethylene by One‐Step Reactive Melt Mixing

ABSTRACTThis study reports the one‐step reactive melt mixing preparation of organic–inorganic hybrid based on maleic anhydride‐grafted polyethylene and 3‐(2‐aminoethyl)aminopropyl‐heptaisobutyl substituted polyhedral oligomeric silsesquioxane, (NPOSS), as well as on low‐density polyethylene and allyl‐heptaisobutyl‐POSS (1POSS) in dicumyl peroxide presence, which is believed to activate the unsaturation of the reactive functional group of POSS itself. The successful grafting of POSS molecules onto polymeric backbones was probed through rheological and spectroscopic analysis. Grafting of POSS molecules enhances their dispersion in the polymeric matrix as shown by morphological analysis. Moreover, the rheological analysis of the organic–inorganic hybrids reveals a solid‐like behavior, due to the formation of a network related to the interactions between grafted POSS molecules. The homogeneous dispersion of POSS molecules along with the strong interaction between polymeric segments and the nanoparticles influences the calorimetric and mechanical properties of the obtained hybrids.