The effect of grafted TMPM on the radiation resistance of polypropylene

The γ‐radiation–induced graft copolymerization of 2,2,6,6‐tetramethyl‐4‐piperidinyl methacrylate (TMPM) onto polypropylene (PP) was investigated using a simultaneous‐irradiation technique. The effects of solvents, atmospheres, dose, and monomer concentration on the percent of grafting were studied. The grafted TMPM showed better thermal stability, solvent extraction resistance, and compatibility with PP than monomeric TMPM or polymeric PTMPM. The stabilizing effectiveness of grafted TMPM on the radiation resistance of PP was found to be better than that of monomeric TMPM. The combination of grafted TMPM and low molecular weight hindered amine light stabilizers showed higher stabilizing effectiveness. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2150–2157, 1999     

Radiation‐induced grafting of pentamethyl hindered amine light stabilizer 1,2,2,6,6‐pentamethyl‐4‐piperidinyl methacrylate onto polypropylene

The γ‐radiation‐induced grafting of 1,2,2,6,6‐pentamethyl‐4‐piperidinyl methacrylate (PMPM) onto polypropylene (PP) was investigated with a simultaneous irradiation technique. The effects of the solvent, dose, monomer concentration, and photoinitiator on the grafting were investigated. The grafting was easier in a benzene solution than in chloroform and acetone solutions. The grafting percentage first increased almost linearly with the irradiation dose until 20 kGy and then increased slowly or remained constant. The grafting percentage increased with the monomer concentration until 1.1 mol/L. The grafting percentage was higher when the proper amount of benzophenone was added. The grafted samples were characterized with Fourier transform infrared spectroscopy and thermogravimetric analysis. Carbonyl groups were found on grafted PP samples, and the carbonyl index increased with the grafting percentage. Thermogravimetric analyses proved the existence of grafted materials on PP, and grafted PMPM thermally decomposed at a lower temperature than PP. The radiation resistance of PP with grafted PMPM was better than that of pristine PP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2157–2164, 2005     

Synthesis of new polymeric stabilizers for polymers

A monomeric stabilizer (M), 2,2,6,6‐tetramethyl‐4‐piperidinyl(6‐methacryloyl amino)hexyl carbamate‐1, was synthesized by a two‐step controlled isocyanation in which methacrylic acid (MAA) reacted in the first step with hexamethylene diisocyanate (HMDI) at a 1 : 1 mol ratio to form an addition product containing one isocyanate group and one unsaturated double bond. In the second step, this product was reacted with 2,2,6,6‐tetramethyl‐4‐piperidinol (TMP) in a 1 : 1 mol ratio at 80°C in the presence of a catalyst dibutyltin dilaurate (DBTDL) to yield M. A new polymeric stabilizer, copolymer P1, was produced from M with methyl methacrylate (MMA) and another copolymer P2 was produced by reacting M with 2‐hydroxy‐4‐benzophenonyl allyl carbamate (AI‐DHBP). Azobisisobutylonitrile (AIBN) was used as an initiator. Their structures, thermal stability, extraction resistance, solubility in organic solvents, and stabilizing effectiveness against photooxidation and thermal oxidation of polypropylene (PP) were characterized by IR, NMR, TGA, and elemental analysis. The results show that both the monomeric and the polymeric stabilizers possess a stabilizing action for protecting PP against photooxidation and thermal oxidation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 403–411, 2000     

一些氮氧自由基和受阻胺化合物对单重态氧的猝灭能力及其与光稳定作用的关系

本工作测定了一系列稳定氟氧自由基(>N—O·)化合物及一些受阻胺光稳定剂对单重态氧(~1O_2)的猝灭速率常数(k_q~~1O_2),发现不同结构的>N—O·对~1O_2的猝灭能力很接近,但它们对聚丙烯(PP)膜的光稳定作用却相差很大。四甲基哌啶醇(TMP)及其衍生物对~1O_2的猝灭能力远不如相应的五甲基哌啶醇(PMP)及其衍生物,但前者对PP的光稳定能力却胜于后者。这说明在对聚合物的光稳定作用中,>N—O·和受阻胺光稳定剂对~1O_2的粹灭作用不占重要地位,也说明~1O_2在PP的光氧化过程中很可能不是主要因素。     

Modification of a fluorine–silicone acrylic resin with a free‐radical‐catching agent

Several kinds of free‐radical‐catching fluorine–silicone acrylic resins with different contents of 2,2,6,6‐tetramethyl‐4‐piperidyl methacrylate (TMPM) were synthesized by solution copolymerization. The chemical structures and properties of the resins were characterized and followed the performances of their respective coatings. The results demonstrate that these kinds of resins showed a high ability to produce nitroxide. The coatings had good thermal stability and hydrophobicity with water contact angles over 100°. Moreover, the weather resistance showed a great improvement for the synergetic protection by bonded TMPM, organic fluorine, and silicone. By aging tests, the modified coatings still maintained excellent mechanical properties with an impact strength and flexibility of 400 N cm and 2 mm, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46385.     

Surface‐activated nanosilica treated with silane coupling agents/polypropylene composites: Mechanical,morphological, and thermal studies

This work reports the mechanical, morphological, and thermal properties of the polypropylene (PP) nanocomposites containing nanosilica (nano‐SiO₂) which were treated by different functional group silane coupling agents. Four types of silane coupling agents namely aminopropyltriethoxy silane (APTES), glycidyloxypropyltrimethoxy silane (GPTMS), trimethoxysilylpropyl methacrylate (TMPM), and dichlorodimethyl silane (DCMS) were used to modify the surface‐activated nanosilica. To enhance the effectiveness of the coupling, nanosilica was chemically activated and analyzed through FTIR and X‐ray photo electron spectroscopy (XPS). The highest tensile strength was recorded by the activated nanocomposites treated with APTES followed by nanocomposite treated with GPTMS, TMPM, and DCMS, respectively. The addition of silane coupling agents into nano‐SiO₂/PP system further improved the tensile modulus of the PP nanocomposites. From the transmission electron microscopy (TEM) analysis, activated nanosilica treated with APTES showed better nanosilica dispersion in the PP matrix and lesser agglomeration occurred when compared with the other silane coupling agents which were used in this study. Surface activation process does not effectively increase the degree of crystallinity and thermal stability on the PP nanocomposites. However, with the assistance of the surface treatment, it was found that the thermal behavior of the PP nanocomposites had been enhanced. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Migration of hindered amine light stabilizers in automotive clearcoats

The diffusion behavior of two hindered amine light stabilizers (HALS) [bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl)-sebacate and bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-sebacate] in an automotive clearcoat has been quantified via time-of-flight secondary ion mass spectrometry. Diffusion couples made from clearcoats with and without HALS allow for the estimation of the diffusion coefficient of one of the HALS. The high diffusion coefficient of one of the HALS contradicts the presence of HALS gradients in weathered coating systems. This discrepancy is ascribed to a decreasing diffusion coefficient of the HALS in the coating matrix due to a weathering-induced increase in the T _g of the clearcoat.     

Characterization of new hindered amine light stabilizers

New polymerizable urethane functional monomers containing hindered amine (III, III′) and their copolymers with styrene (S) and methyl methacrylate (MMA) are characterized and tested as hindered amine light stabilizers (HALS). Experimental results indicated that the monomers possess high photostabilizing effectiveness comparable to that of Tinuvin 770 and Tinuvin 765. Their copolymers with S and MMA showed lower photostabilizing effectiveness mainly due to the low hindered amine content in the copolymers. The copolymers, however, showed very high resistance to liquid extraction. UV and ESR analyses indicate that the photostabilizing mechanism of these HALS is through the scavenging action of nitroxyl radicals formed from degradation of the substrate polymer. © 1993 John Wiley & Sons, Inc.     

Enhancement of UV-aging resistance of UV-curable polyurethane acrylate coatings via incorporation of hindered amine light stabilizers-functionalized TiO<Subscript>2</Subscript>-SiO<Subscript>2</Subscript> nanoparticles

In this study, polymeric hindered amine light stabilizers (HALS)-functionalized silica coated rutile titanium dioxide (TiO₂-SiO₂) nanoparticles were prepared by encapsulating commercially available TiO₂-SiO₂ nanoparticles with methyl methacrylate (MMA) and 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (PMPM) copolymers via miniemulsion polymerization. The obtained functional (TiO₂-SiO₂/P(MMA-co-PMPM)) fillers have been added to polyurethane acrylate (PUA) oligomers to get UV-curable nanocomposite coatings. The functionalization of the TiO₂-SiO₂ nanoparticles with polymeric HALS has been confirmed by infrared spectra (IR), thermogravimetric (TG), and X-ray photoelectron spectroscopy (XPS) analyses. The scanning electron microscope (SEM) micrographs indicated that homogeneous dispersion of TiO₂-SiO₂/P(MMA-co-PMPM) composite nanoparticles resulted in improved transparency and mechanical properties of the UV-curable PUA coatings. Rhodamine B (Rh.B) photodegradation measurement confirmed the excellent UV-shielding performance of PUA nanocomposite coatings containing TiO₂-SiO₂/P(MMA-co-PMPM). The addition of TiO₂-SiO₂/P(MMA-co-PMPM) composite nanoparticles reduced the UV-curable PUA coatings degradation rate dramatically. The UV-aging resistance of PUA coatings was improved significantly. Over all, the combination of TiO₂-SiO₂ nanoparticles and polymeric HALS offers an attractive way to fabricate the multi-functional fillers, which can be used to improve the mechanical properties and UV-aging resistance of PUA coatings simultaneously.     

Effect of antiaging agents on the outdoor natural weathering of bamboo powder/polypropylene foamed composites

The effect of outdoor natural weathering on the properties of injection molded 33 wt% bamboo powder (BP)/polypropylene (PP) foamed composites with and without the antioxidant and hindered amine light stabilizers (HALS) were investigated. The composites containing the antiaging agents had higher color stability, slightly greater retentions of flexural modulus, tensile and notched impact strengths, higher creep resistance, and better rheological stability than the reference composite. The antiaging agents of pentaerythritol tetrakis(3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)propionate) and poly‐(n‐hydroxyethyl‐2,2,6,6‐tetramethyl‐4‐hydroxy‐piperidyl succinate) had more beneficial effect than n‐octadecyl‐β‐(4‐hydroxy‐3,5‐di‐tert‐butyl‐phenyl)‐propionate and bis(2,2,6,6‐tetramethyl‐4‐piperidinyl)sebacate. After 12 months of exposure, △E^* decreased from 22.8 of the reference composite to 9.9 of the composite with the antiaging agents. Rheological behavior results indicated that the storage modulus, complex viscosity, and non‐Newtonian fluid index of composites containing the antiaging agents were slightly increased. Natural weathering caused less decreases in the storage and loss moduli, crossover modulus, relaxation time, and average molecular weight for composites containing the antiaging agents than those for the reference composite. Environmental scanning electron microscopy (ESEM) observation confirmed the improved surface durability for composites containing the antiaging agents. J. VINYL ADDIT. TECHNOL., 22:311–319, 2016. © 2014 Society of Plastics Engineers     

Synthesis of novel polymeric HALS stabilizers and chain transfer effect of hindered amine norbornene derivatives on ring-opening metathesis polymerization

Cyclooctadiene (COD) was polymerized via ring-opening metathesis polymerization (ROMP) in the presence of 5-norbornene-exo, endo-2-carboxylic acid 2,2,6,6-tetramethyl-4-piperidinyl ester (PN) or 5-norbornene-2-exo-3-endo-dicarboxylic acid bis(2,2,6,6-tetramethyl-4-piperidinyl) ester (2,3-PN) to prepare a new kind of polymeric hindered amine (HALS) stabilizers. Unexpectedly, hindered amine norbornene derivatives PN and 2,3-PN did not act as comonomer but acted as chain transfer agent (CTA). The resulting polymers were characterized by gel permeation chromatography (GPC) and ¹H-NMR. Investigation of polymerization behavior showed that hindered amine groups were introduced into polymer chain by virtue of chain degradation resulted from chain transfer. The molecular weight (M _n) and HALS content of the resulting polymeric HALS stabilizer could be regulated by varying molar ratio of initial monomer to catalyst.     

Synthesis and polymerization of methacrylate bearing a phosphorylcholine, analogous moiety

Summary A new type of methacrylate bearing a phosphorylcholine analogous moiety, 2-[2'-(trimethylammonium)-1-methylethyl-phosphoryl]ethyl methacrylate (TMPM) was synthesized. TMPM was radically homopolymerized and copolymerized with BMA to obtain the polymers. The critical micelle concentration (CMC) of TMPM was 4.9 × 10⁻² mol/l according to the fluorescent probe method. Received: 11 June 2001/Revised version: 30 July 2001/Accepted: 31 July 2001     

Synthesis and properties of new copolymers containing hindered amine

Eight new copolymers containing hindered amine (HA) were synthesized by copolymerization of vinyl monomers [styrene (St), methyl methacrylate (MMA)] with new functional monomers produced by reaction of 4-amino-2,2,6,6-tetramethylpiperidine (ATMP) and epoxy compounds containing double bond, and mixture copolymerization of vinyl monomers (St and MMA) with a mixture of ATMP and above epoxy compounds. The structure of these new copolymers were characterized by IR, NMR, and elemental analysis. The properties of these new copolymers were described and their photoprotecting effectiveness examined. Experimental results indicate that they possess high photoprotecting effectiveness comparable to or higher than that of a commercial polymeric HALS “PDS.” © 1996 John Wiley & Sons, Inc.     

A fluorine–silicone acrylic resin modified with UV-absorbing monomers and a free radical scavenger

A novel UV-absorbing and free-radical-catching fluorine–silicone acrylic resin with 2-(4-benzoyl-3-hydroxyphenoxy) ethyl acrylate (BHEA), 2,2,6,6-tetramethyl-4-piperidyl methacrylate (TMPM), dodecafluoroheptyl methacrylate (DFMA) and 3-methacryloxypropyltrimethoxysilane (MPS) as functional monomers was successfully synthesized by solution copolymerization. Based on various investigations, our characterization results for the resin and its coating indicated that the resin exhibits high UV-absorbing and free-radical-catching performances, and the hydrophobicity of the varnish coating was promoted by the actions of fluorine and silicone. In addition, the weatherability improved because of the enduring triple protection of the UV absorbent (BHEA), free-radical-catching agent (TMPM), fluorine (DFMA) and silicone (MPS). After a 1000-h aging test, the color difference (?E) and rate of loss of gloss (?G) of varnish coatings were 2.96% and 62%, respectively, and the impact strength and flexibility of color paint coatings were 420 N cm and 2 mm, respectively. Moreover, the chemically bonded free-radical-catching agent (TMPM) showed a more enduring performance for producing nitroxides than the simple blend.     

TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> composite nanoparticles containing hindered amine light stabilizers encapsulated by MMA–PMPM copolymers

TiO₂–SiO₂ composite nanoparticles containing hindered amine light stabilizers (HALSs) were prepared by encapsulation of commercially available TiO₂–SiO₂ nanoparticles using methyl methacrylate (MMA) and 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (PMPM) copolymers through mini-emulsion polymerization. The Fourier transform infrared spectral analysis (FTIR) showed that the hindered amine light stabilizer PMPM was incorporated into the TiO₂–SiO₂/P(MMA-co-PMPM) composite nanoparticles. The X-ray photoelectron spectroscopy analysis (XPS) showed that the surface of TiO₂–SiO₂ nanoparticles was enriched with HALS moieties. The formation of P(MMA-co-PMPM) random copolymers on the surface of TiO₂–SiO₂ nanoparticles was determined by differential scanning calorimetry (DSC), and the percentage of the chemically grafted P(MMA-co-PMPM) coverage on the TiO₂–SiO₂ nanoparticles surface was 40.9 wt% determined by thermogravimetric analysis (TGA), which revealed that the TiO₂–SiO₂ nanoparticles were successfully encapsulated by MMA–PMPM copolymers. Scanning electron microscopy analysis indicated that the TiO₂–SiO₂/P(MMA-co-PMPM) composite nanoparticles were mainly homogeneous spherical shape particles, with an average size of about 90 nm. Rhodamine B (Rh.B) photocatalytic degradation study revealed UV-shielding characteristics for TiO₂–SiO₂/P(MMA-co-PMPM) composite nanoparticles and showed a remarkable decrease in photocatalytic activity of TiO₂–SiO₂ nanoparticles. These results indicated that TiO₂–SiO₂/P(MMA-co-PMPM) composite nanoparticles may be promising light stabilizers with covalent functionalization of polymeric HALS, which has little photocatalytic activity, and can be introduced into the weathering-resistant polymer materials to improve their application properties.     

Study of TATP: Formation of New Chloroderivates of Triacetone Triperoxide

The existence of two new types of chloroderivates of cyclic acetone peroxides – 3‐(chloromethyl)‐3,6,6,9,9‐pentamethyl‐1,2,4,5,7,8‐hexoxonane and 3,6‐bis(chloromethyl)‐3,6,9,9‐tetramethyl‐1,2,4,5,7,8‐hexoxonane was proved by HPLC/MS/MS and NMR in the reaction products when acetone and hydrogen peroxide are mixed in the presence of excess hydrochloric acid (molar ratio hydrochloric acid to acetone n_c/n_a=2.5). The details of analysis, and the conditions under which these asymmetric chloroderivates of cyclic peroxides form, are described.     

Synthesis of phosphorus‐containing flame‐retardant antistatic copolymers and their applications in polypropylene

By adjusting the molar ratios of antistatic monomer of octyl phenol ethylene oxide acrylate (denoted as AS), rigid monomer of methyl methacrylate (denoted as MMA), and flame‐retardant monomer of 2‐(phosphoryloxymethyl oxyethylene) acrylate (denoted as FR), a series of flame‐retardant antistatic copolymers poly (octyl phenol ethylene oxide acrylate‐co‐methyl methacrylate‐co‐phosphoryloxymethyl oxyethylene acrylate) (donated as AMF) were synthesized through radical polymerization. Among the obtained copolymers, two copolymers, AMF162 (the feed molar ratio of AS, MMA, and FR as 1 : 6 : 2) and AMF1104 (the feed molar ratio of AS, MMA, and FR as 1 : 10 : 4) with different concentrations were added into polypropylene (PP) to prepare PP‐AMF162 and PP‐AMF1104 series of composites. The thermal stability, limiting oxygen index, the antistatic property, and mechanical properties of PP composites were tested and analyzed. PP‐AMF162 series composites have excellent antistatic effect. When the AMF162 content was equal to or <15 wt %, the impact strength of PP‐AMF162 composites was higher than that of pure PP. The results indicated that copolymer AMF162 was a suitable flame‐retardant and antistatic additive for PP. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41677.     

Nondegradative melt functionalization of polypropylene with glycidyl methacrylate

The melt grafting of glycidyl methacrylate (GMA) onto powdered isotactic polypropylene (PP) in a Haake Rheocord RC90 mixer was studied. Grafting degrees were determined by nonaqueous back titration of trichloroacetic acid with sodium hydroxide. The extent of degradation and crosslinking of PP during grafting was indicated by the melt-flow rates (MFR) of the grafted samples. The influences of GMA concentration, initiator type and concentration on grafting degree, reaction efficiency, and degradation were evaluated. A novel method was developed to obtain a high grafting degree with little degradation of PP using acrylamide (AM) as the initiating agent. The grafting process occurred before or during the melting of PP (i.e., solid-state grafting), at which temperature crosslinking is preferred over chain scission. Primary free radicals generated from the rapid decomposition of AM have a higher tendency to attack GMA molecules than PP chains. At the same estimated amount of primary radicals, both grafting degree and grafting efficiency increase with decreasing decomposition temperature of the initiator (for the same decomposition half-life) in the order of AM > benzoyl peroxide (BPO) > 2,5-di(t-butylperoxy)-2,5-dimethyl-3-hexyne (LPO). FunctionalizedPP with the desired grafting degree and little degradation of PP could be obtained by the use of mixed initiators. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1957–1963, 1998     

Chemical degradation and failure analyses by acoustic emission of PP/EOC blends exposed to ultraviolet radiation

In this work, acoustic emission was used to investigate the effects of ultraviolet radiation on the mechanical behavior of blends of polypropylene (PP) with ethylene-octene copolymer (EOC) containing photo stabilizers. Together with traditional techniques, like infrared spectroscopy and microscopy, the data obtained from acoustic emission helped the understanding of the failure caused by photodegradation and the influence of the stabilizing additives. Parameters like number and intensity of hits, released energy and acoustic events were recorded and related to the estate of the degradation and to the stress-strain behavior. The results confirmed the high sensitivity of PP/EOC blends to ultraviolet and the better performance of stabilized compounds, especially when hindered amine light stabilizers (HALS) were present. Acoustic emission experiments showed that in stabilized samples the crack propagation took place over a larger time interval, releasing more energy during failure and, hence, postponing the final fracture, from a few seconds for the neat blend to more than 500 seconds for the samples with 0.5% HALS.     

受阻胺光稳定剂(HALS)在聚合物材料上的应用

介绍了受阻胺光稳定剂(HALS)的稳定机理.讨论了其他稳定剂对其光稳定效果的影响.实验表明:HALS单独使用耐候性不佳,与其他稳定剂复配使用可得较好的结果.此外,一些HALS还能改善聚合物材料的阻燃性能.