Abstract
To obtain a high transmittance blend within ultraviolet and visible regions, various transparent samples of ascending percentages of polymethylmethacrylate (PMMA)/cellulose acetate propionate (CAP) were prepared by melt blending using a twin screw extruder. These blends were characterised by ultraviolet-visible spectroscopy, and the curves illustrated that the blending ratio of 10% CAP in PMMA meets the required purpose. The morphological, mechanical, and thermal properties for pure PMMA and the PMMA/CAP 10% blend were investigated using X-ray diffraction, scanning electron microscopy, dynamic mechanical analysis, and thermogravimetric analysis. The results showed that the PMMA/CAP 10% blend has an amorphous structure and low stiffness than pure PMMA. The miscible PMMA/CAP 10% blend exhibited mechanical stability below the glass transition temperature (Tg), with a slight increase in Tg value relative to that of pure PMMA. The study also demonstrated that the intermolecular interaction between blend elements has an effective influence on the physical properties of the blend.
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Miscible Transparent Polymethylmethacrylate/Cellulose Acetate Propionate Blend: Optical, Morphological, and Thermomechanical Properties
Raouf Mahmood Raouf,a,b,* Zaidan Abdul Wahab,a Nor Azowa Ibrahim,c,d Zainal Abidin Talib,a and Buong Woei Chieng c,d
To obtain a high transmittance blend within ultraviolet and visible regions, various transparent samples of ascending percentages of polymethylmethacrylate (PMMA)/cellulose acetate propionate (CAP) were prepared by melt blending using a twin screw extruder. These blends were characterised by ultraviolet-visible spectroscopy, and the curves illustrated that the blending ratio of 10% CAP in PMMA meets the required purpose. The morphological, mechanical, and thermal properties for pure PMMA and the PMMA/CAP 10% blend were investigated using X-ray diffraction, scanning electron microscopy, dynamic mechanical analysis, and thermogravimetric analysis. The results showed that the PMMA/CAP 10% blend has an amorphous structure and low stiffness than pure PMMA. The miscible PMMA/CAP 10% blend exhibited mechanical stability below the glass transition temperature (Tg), with a slight increase in Tg value relative to that of pure PMMA. The study also demonstrated that the intermolecular interaction between blend elements has an effective influence on the physical properties of the blend.
Keywords: Cellulose acetate propionate; Poly (methylmethacrylate); Miscible; Ultraviolet; Blend
Contact information: a: Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia; b: Materials Engineering Department, College of Engineering, Al-Mustansiriyah University, Baghdad, Iraq; c: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia; d: Materials Processing and Technology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia; *Corresponding author: raoufmahmood@yahoo.com
INTRODUCTION
Polymer blends are regarded as an effective way to obtain new products, and for problem-solving by providing the ability to control characteristics without the creation or invention of new polymers. Physically mixing two or more polymers often yields immiscible or partially miscible blends (Manson 2012); however, miscibility in the polymer blend is the property we hoped to achieve in this study. Although there are a number of studies that have reported miscibility in polymer blends (Edgar et al.2001; Bhat and Jois 2014; Bourara et al. 2014; Bao et al. 2015; Huang et al. 2015), it is an infrequent occurrence, so it is treated as a special case (Paul 2012). Some thermodynamic factors are interconnected in a complex way to the polymer-polymer interaction such as miscibility, adhesion, and interfacial energies (Park et al. 2014). Two-polymer miscibility is mostly caused by a negative heat of mixing. This can be achieved by particular interactions between the constituent particles of the blend (Nesterov and Lipatov 1998; Olabis 2012). Generally, miscible polymer blends are structurally homogeneous and thermodynamically stable; this can be seen morphologically by the lack of interface between the blend phases, so the comparable term is used to describe single-phase behaviour (Olabis 2012; Paul 2012). Furthermore, a miscible polymer blend shows a single glass transition temperature (Tg) for its components (Gajria et al. 1996; Olabis 2012); otherwise, there will be several peaks for each component of the immiscible blend (Manson 2012).
Poly (methylmethacrylate) (PMMA) is an important thermoplastic engineering polymer because of its wide application in several areas, including optics. Its light weight and high transparency have made it a viable alternative to glass. As a result of direct contact with weather conditions, especially ultraviolet (UV) radiation, PMMA suffers from scission (Davis and Sims 1983; Choi et al. 1988; Torikai et al.1990; Choi et al. 2001). It has been found that the photodegradation of PMMA in air leading to random scission starts with the decomposition of side-chains (ester side groups) and ends with main chain scission (Fox et al. 1963; Davis and Sims 1983; Caykara and Güven 1999). The most important products of PMMA scission are hydrogen, methane, carbon dioxide, and carbon monoxide. During exposure to radiation, the UV absorption of PMMA increases because of the chromophoric groups (Fox et al. 1963). Chromophoric groups such as the carbon-carbon double bonds (C=C) and carbonyl groups (C=O), which are able to absorb UV energy, will be involved in the photochemical degradation reactions that occur via free radical mechanisms, leading to the formation of hydroperoxides and chain scission (Davis and Sims 1983; Clough and Shalaby 1991; Dole 2013). The UV irradiation causes random chain scission, leading to variations in molecular mass, Tg, and spectra, as well as the loss of volatile particles from PMMA (Abouelezz and Waters 1978, Torikai et al. 1990).
Recent research has focused on the use of biodegradable materials such as cellulose esters in the formation of layers or blends to handle some of their polymer optical, mechanical, and thermal properties (Nobukawa et al. 2014; Park et al. 2014; Kunthadong et al. 2015; Nobukawa et al. 2015). Cellulose acetate propionate (CAP) is an amorphous, transparent, and thermally stable polymer belonging to the cellulose ester family that has attracted attention from scientists because of its biocompatibility and properties intermediate between cellulose acetate and cellulose acetate butyrate. In CAP, a hydrogen bond with the presence of hydroxyl groups and ester carbonyl groups plays an important role in forming a homogeneous polymer blend (Edgar et al. 2001; Bhat and Jois 2014; Bourara et al. 2014). It was reported that the orientation birefringence behaviour of cellulose ester blends with polymers has a significant influence on the optical properties of the blend, whereas the unusual wavelength distribution of the orientation behaviour of CAP macromolecules is due to the polarisability anisotropy of ester groups. In addition, the orientation birefringence of CAP is reliant on the ratio of draw and draw temperature; furthermore, the molecular mass also affects the orientation birefringence (Rinderknecht and Brisson 1999; Park et al. 2005; Yamaguchi et al. 2009). It is noteworthy that the interaction of the two phases enhances the synergistic effect, which leads to improved thermal stability of the CAP/polymer blend (Souza et al. 2012). The aim of this work was to reduce the photochemical reaction between transparent samples of different percentages of PMMA/CAP blends and UV radiation by making use of the unusual optical properties of CAP. Reducing the ability for interaction comes through looking for the best blending ratio of CAP into PMMA to make the blend more transparent in the UV region (less absorbance for UV radiation). The blend is supposed to be transparent in the UV area while maintaining transparency in the visible region.
EXPERIMENTAL
Materials
White powder CAP (average Mn ~15,000) and white powder PMMA (average Mw ~120,000 by GPC) were supplied by Sigma-Aldrich (USA).
Methods
Sample preparation was performed in two steps. The first was kneading the basic components of each concentration and the second was moulding the mix. The polymers were pre-dried in a vacuum oven at 50 °C for 4 h. The CAP/PMMA blend was prepared using a Thermo HAAKE PolyDrive Internal Mixer (Germany) (D = 19.05 mm).
To prepare the PMMA/CAP samples, a fixed weight of PMMA was melt-kneaded in the extruder at a rotation rate of 50 rpm at 130 °C for 10 min. Then, variable percentage weights of CAP (5%, 7%, 9%, etc. up to 20%) were added to the molten PMMA. Mixing continued until a constant torque was reached, which took about 15 min. The samples were transparent and homogeneous. After that, each blended sample was pressed by a hot press from the Hsin-Chi Machinery Co., Ltd., (Taiwan) at 110 kPa and 130 °C to form a sheet 70 mm × 90 mm and 1 mm thick.
Measurements
The transparency and absorbance nature of the samples were determined using ultraviolet-visible (UV-VIS) spectroscopy (Shimadzu UV-3600 spectrophotometer, Japan). Surface images were obtained using scanning electron microscopy (SEM) studies on a Hitachi S-3400N (Japan) microscope. The amorphosity of the samples was investigated using X-ray diffraction (XRD). The XRD patterns were recorded with an X-ray diffractometer (Philips PANalytical X’Pert Pro MPD – PW 3040/60, Netherlands). The diffractometer data were obtained from 2θ = 20° to 80° with a scanning speed of 5°/min at room temperature. The thermal behaviour of the prepared samples was examined by a TGA/DSC1 STAR System (USA) thermogravimetric analyser at a heating rate of 10 °C/min from 50 to 1000 °C in nitrogen atmosphere. Dynamic mechanical analysis (DMA) was carried out on a Perkin Elmer Pyris Diamond (USA) device in tension mode at a frequency of 1 Hz a nd a heating rate of 10 °C/min in a liquid nitrogen atmosphere.
Characterisation
The optical characteristics within the UV and visible spectra were evaluated from 220 to 800 nm for transparent pure PMMA samples using a Shimadzu UV-3600 spectrophotometer. Results revealed a clear absorbance peak in the UV region for pure PMMA at 226 nm. The absorbance of high photon energy within the UV region led to scission in the polymer chain. More precisely, chromophoric groups, which are capable of absorbing the UV energy involved in the photochemical degradation reactions that occur via free radical mechanisms, led to the formation of hydroperoxides and chain scission of the polymer (Charlesby and Thomas 1962; Abouelezz and Waters 1978; Michelson et al.2012). The transmittance peak for pure PMMA in the visible region was 798 nm. The transmittance peak in the visible region signifies the actual performance for pure PMMA (Moore and Ferreira 2006; Osuagwu and Ogbuehi 2014). The sample transparency as well as absorbance and transmittance peak values were relied upon for all subsequent measurements on the blended samples under study.
RESULTS AND DISCUSSION
UV-VIS Spectroscopy
The absorbance and transmittance spectroscopy curves, in addition to the spectra and visual appearance of the PMMA/CAP blends, are shown in Fig. 1.
A preliminary study of the optical properties was carried out, investigating specifically the absorbance and transmittance within the UV and visible regions. Initial concentrations of CAP in PMMA were 5%, 10%, 15%, and 20%. The absorbance versus concentration curve for these four concentrations demonstrated that the lowest value of absorbency was at 10% CAP, i.e., approximately 2.572 (the absorption of pure PMMA is 3.408), with transparency up to 87.561%. New samples were prepared and added (7%, 9%, 10%, 11%, 13%, and 15%) to make a full examination of the low absorbance area (10% CAP). Three samples were tested from each concentration, and then the average for each concentration was determined to calculate the values of absorbance and transmittance.
Figure 1(a) shows the absorbance versus concentration curves for pure PMMA and PMMA/CAP% blends. The decline in the value of the absorption curve is clear at 10% CAP. This decline in the value of absorption corresponds with a transmittance peak in the same concentration, 10% CAP, at the threshold of 226 nm. Figure 1(b) shows two transmittance peaks, one at a concentration of 10% CAP and the other at 15% CAP. The peak value of transmittance at 15% CAP was higher than at 10% CAP (89.41 and 88.64, respectively), but at 15% CAP the peak value had a high absorbance within the UV area (3.003), as can be seen in Fig. 1(a). Therefore, 10% CAP was chosen as the highest concentration. The selection of PMMA/CAP10% as the best blend concentration met the required purpose of the work, which was to achieve the lowest absorbency of optical radiation within the UV region, especially at the damage threshold of PMMA (226 nm). The absorbance and transmittance curves for pure PMMA and all concentrations are shown in Fig. 1(c). From the transmittance curves, it seems clear that the optical transmittance of pure PMMA and PMMA/CAP10% are approximately compatible, with some shifting into the visible region at 10% CAP. This demonstrates that the transparency behaviour of the PMMA/CAP10% blend matches that of pure PMMA.
Making the PMMA/CAP10% blend more transparent to UV radiation led to a reduction in the amount of damage that resulted from photochemical degradation reactions (Davis and Sims 1983), meaning that it reduced the severity of the interaction between UV radiation and the carbonyl groups (chromophoric groups) of the PMMA/CAP10% blend (Salamone 1998). The PMMA/CAP10% blend minimises peroxide formation and chain scission (Torikai et al. 1990; Caykara and Güven 1999; Dole 2013). It seems obvious from the absorbance curve that 10% CAP concentration in PMMA gave less absorbency in the UV region. This may be due to the nature of the chemical bonding between CAP and the PMMA backbone in the composition (Edgar et al. 2001; Manaf et al. 2011), while a high transparency of the sample of about 88.64% was maintained.
The difference in the absorbance and transmittance values with concentration variation, as shown in Fig. 1 (a,b), can be attributed to the polarizability anisotropy of ester groups (Yamaguchi et al. 2009). That means, with respect to the wavelength dependence of the propionyl or acetyl group, one can expect unusual dispersion with positive or negative orientation birefringence.
Fig. 1. (a) Absorbance of PMMA and CAP in different concentrations at 226 nm; (b) transmittance of PMMA and CAP in different concentrations at 798 nm; (c) PMMA/CAP absorbance and transmittance spectrum with concentrations; (d) PMMA/CAP sheets in different concentrations
Even in the case of a single polymeric material, not polymer blends, one may observe unusual dispersion (Yamaguchi et al. 2009). The transparency curve shows that there was a clear creep towards the visible region from 10% CAP down to 15% CAP concentration. This property has wide applications in different optical fields (Edgar et al. 2001; Yamaguchi and Masuzawa 2007a; Manaf et al. 2011). The PMMA/CAP blend samples started to become cloudy with increasing CAP concentration in PMMA. Samples with concentrations higher than 20% were discarded because they did not meet the required purpose (Fig. 1(d)).
X-Ray Diffraction
The XRD diffractograms for pure PMMA and the PMMA/CAP10% blend are shown in Fig. 2. The amorphous structure of pure PMMA and the PMMA/CAP10% blend did not have long-range order and therefore made broad scattering peaks. Broad peaks in XRD diffractograms are a typical characteristic of amorphous materials and are known as amorphous humps (Guinier 1994). The values obtained from the diffractograms show that there was a difference in the intensities of pure PMMA and PMMA/CAP10% peaks.
The intensity of the PMMA/CAP10% peak was approximately three times higher than the peak of pure PMMA. Moreover, there was a clear shift of the peaks after the addition of 10% w/w CAP to PMMA increasing towards 2θ. This implies that 10% w/w CAP has maintained random situation and that complication took place between the CAP composition and PMMA structure in the amorphous region. The increasing intensity and shift of the peaks confirm the occurrence of stereochemistry complication between PMMA and CAP (Gupta and Singh 1996; Ramesh et al. 2010). In other words, the shift of the peaks confirms that interactions happened between PMMA and CAP structure (Ramesh and Arof 2001).The intensity of characteristic peaks increased after 10%CAP addition because of increase the arranged areas in the PMMA backbone (Ramesh et al. 2010).
Fig. 2. XRD patterns for pure PMMA and PMMA/CAP10%
Dynamic Mechanical Analysis
Thermomechanical behaviour is commonly studied using the DMA technique. This technique is based on applying a small deformation (oscillatory force) to a sample in the cyclical mode and reporting changes in stiffness. A DMA scheme includes three basic curves (the storage modulus E‘ curve—the ability of the material to store potential energy, loss modulus E” curve—energy dissipation in the form of heat upon deformation, and the phase angle tan δ curve—the mechanical damping or internal friction) in a viscoelastic system versus temperature (Mathur et al. 2003; Menard 2008).
The storage modulus, loss modulus, and phase angle versus temperature within a range of −10 to 130 °C for pure PMMA and the PMMA/CAP10% blend are shown in Figs. 3(a) and (b). The storage modulus E‘ curves for pure PMMA and the PMMA/CAP10% blend were similar in general appearance, and they showed a marked decrease with increasing temperature. Moreover, the E‘ curves did not show any clear milestones for the three deformation stages in the glassy region, as one can see them move smoothly from secondary dispersion passing through Hookean behaviour (gamma relaxation) to the second transition (beta relaxation). The onset temperature for pure PMMA and the PMMA/CAP10% blend moved from the glassy region to the rubbery region (glass transition) at 80 °C. The rubbery region started with a primary transition (alpha relaxation); in this region the E‘ curve strongly descended down to the high visco-rubbery region (visco-elastic fluid); it did not stay long in this area, moving to the flow (melt) region. The E” curve for the PMMA/CAP10% blend was close to that of pure PMMA, and through Tg they were at a maximum.
Generally, E‘ curves are typical for amorphous thermoplastics. Therefore, at low temperatures, pure PMMA and PMMA/CAP10% blend molecules are unable to resonate with the oscillatory loads and hence remain stiff. This is apparent on the E‘ curve by the absence of the three deformations within the glassy region. In other words, the polymeric side groups are not able to rotate about the C—C bonds, so the molecular side groups behave as rigid crosslinks (Heijboer et al. 1987; Menard 2008; Merenga and Katana 2010). At 80 °C, the pure PMMA and PMMA/CAP10% blend molecules moved to the alpha relaxation region, which is the main chain motion area. In this region (the glass transition region), the E‘ curve fell during heating to a level a thousandth of its original value. The E‘ curve left the alpha relaxation region at 120 °C for the rubbery region (Fekete and Pukánszky 2005; Merenga and Katana 2010). The addition of 10% CAP to PMMA led to a clear decline in the values of E‘ and E” at lower temperatures.
There is a slight shift for tan δ curve peak for PMMA/CAP10% blend, which suggested that the presence of CAP molecules caused a decrease in the free volume related to the segmental motion of PMMA at high temperatures near Tg. With decreasing of the free volume, the amplitude of the local motion for beta relaxation becomes smaller (Yamaguchi and Arakawa 2007b; Nobukawa et al. 2013).
The identical tan δ curve peak at 105 °C for PMMA and PMMA/CAP10% represents the Tg for atactic miscible PMMA (Bosma et al. 1988; Teng et al. 2009; Olabis 2012). The decrease in the values of E‘ and E” for the PMMA/CAP10% blend is a sign of more freedom in the polymer chain movement (Heijboer et al. 1987), leading to decreased hardness of the blend.
Fig. 3. Storage modulus E‘, loss modulus E“, and tan δ trace for (a) pure PMMA and (b) PMMA/CAP10%
Thermogravimetric Analysis
The mass loss rate versus temperature thermograms for pure PMMA and the PMMA/CAP10% blend are plotted in Figs. 4(a) and (b).
The thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) thermograms of pure PMMA show three thermal degradation areas beginning at 280 °C with a total mass loss of ≈27% due to head-to-head linkage scission (weak links) (Kashiwagi et al. 1986; Manring et al. 1989), then at 384 °C with a total mass loss ≈47% because of unsaturated vinyl end decomposition that leads to cleavage from the chain end (Kashiwagi et al. 1986; Wang et al. 2005). The third and last degradation at 525 °C with a total mass loss of ≈15% was caused by PMMA main chain random scission (Kashiwagi et al. 1986; Manring et al. 1989).
The first order reaction must have occurred during thermal degradation after random chain and/or chain-end scission. Random scission is caused by the pre-oxidation of PMMA as a result of air exposure. At high temperatures, during depropagation, intramolecular transfer is responsible for oligomer formation by the elimination of an unsaturated end group and thus for molecular weight degradation (Lehrle and Place 1997; Holland and Hay 2001; Hu and Chen 2003).
In Fig. 5(b), the PMMA/CAP10% blend TGA and DTG diagrams show two thermal degradation stages. The first at 310 °C with a total mass loss of ≈1% was caused by the degradation of the substitute parts of the CAP chain, and the second at 400 °C with a total mass loss of ≈98% is attributed to the degradation of the blend backbone (polymer main chain) (Jeon et al. 2012; Allue and Botaro 2012). The TGA trace shows that PMMA has a high residue (7.1853%) and thermal stability than the PMMA/CAP10% blend (0.6222%).
Fig. 4. TGA and DTG thermograms for (a) pure PMMA and (b) PMMA/CAP10%
Scanning Electron Microscopy
The characteristic features of pure PMMA and the PMMA/CAP10% blend obtained from SEM are shown in Fig. 5. The SEM images for each sample are shown at three different magnifications (2, 5, and 10 µm). The pure PMMA surface images illustrate, unambiguously, uniform morphological features, representing a single material (homopolymer) (Fig. 5(a–c)) (Silverstein et al. 2014).
No collective configuration and boundary were noted in the PMMA/CAP10% blend images (Fig. 5(d–f)). The homogeneity of the blend can be seen as evidence of its miscibility. The polar interactions between the blend components and the nature of their spread in the blend matrix have an active role in making the blend homogeneous and stable against phase separation. Furthermore, the formation of hydrogen bonds in the carbonyl group of PMMA helps the amorphous phases in the blend to become miscible (Jeong et al. 2000; He et al. 2004; Bhat and Kumar 2006; Dixit et al. 2009; Bourara et al.2014). The high homogeneity polymer blend shows homopolymer behaviour. This seems to be in agreement with the DMA and TGA results. In DMA, there was no change in the overall shape of the curves, nor to the constancy of Tg after adding 10% CAP. As for TGA, the improvement in thermal stability was very clear (Bourara et al. 2014).
Fig. 5. SEM images for PMMA and the PMMA/CAP10% blend with different scale bars; (a) PMMA/10 µm; (b) PMMA/5 µm; (c) PMMA/2 µm; (d) PMMA/CAP10%/10 µm; (e) PMMA/CAP10%/5 µm; (f) PMMA/CAP10%/2 µm
CONCLUSIONS
- Transparent blends of PMMA and CAP were achieved by melt blending. The UV-VIS spectrum showed that pure PMMA has an absorbance peak (3.408) at approximately 226 nm with transmittance up to 84.29% at 798 nm, whilst blending 10% CAP with PMMA provides less absorbency in the UV region (2.572), with high transmittance (88.53%) at the same wavelengths.
- The TGA investigations show that the PMMA/CAP10% blend has less thermal stability than pure PMMA. This could be attributed to the rearrangement that occurred during the mixing process.
- The DMA results confirmed that the modulus of the PMMA/CAP10% blend was lower than that of pure PMMA, and that both of them were mechanically stable below Tg. The tan δ curve peak at 105 °C clarified that PMMA is an atactic miscible polymer.
- The amorphous structure of pure PMMA and the PMMA/CAP10% blend can be explained by amorphous humps in XRD curves with an increase in the intensity of the peaks and creep in the PMMA/CAP10% blend. As a result, CAP provides a high level of enhancement to protect PMMA from UV radiation.
REFERENCES CITED
Abouelezz, M., and Waters, P. (1978). “Studies on the photodegradation of poly (methyl methacrylate),” DTIC Document, USA.
Allue, P. D., and Botaro, V. R. (2012). “Synthesis and characterization of a new cellulose acetate-propionate gel: Crosslinking density determination,” Open Journal of Polymer Chemistry 2(4), 144-151. DOI: 10.4236/ojpchem.2012.24019
Bao, C. Y., Long, D. R., and Vergelati, C. (2015). “Miscibility and dynamical properties of cellulose acetate/plasticizer systems,” Carbohydrate Polymers 116, 95-102. DOI: 10.1016/j.carbpol.2014.07.078
Bhat, D. K., and Jois, H. S. (2014). “Miscibility and conductivity studies of poly (methyl methacrylate) and cellulose acetate phthalate blends,” Procedia Materials Science 5, 995-1004. DOI: 10.1016/j.mspro.2014.07.388
Bhat, D. K., and Kumar, M. S. (2006). “Biodegradability of PMMA blends with some cellulose derivatives,” Journal of Polymers and the Environment 14(4), 385-392. DOI: 10.1007/s10924-006-0032-5
Bosma, M., Brinke, G. T., and Ellis, T. S. (1988). “Polymer-polymer miscibility and enthalpy relaxations,” Macromolecules 21(5), 1465-1470. DOI: 10.1021/ma00183a041
Bourara, H., Hadjout, S., Benabdelghani, Z., and Etxeberria, A. (2014). “Miscibility and hydrogen bonding in blends of poly (4-vinylphenol)/poly (vinyl methyl ketone),” Polymers 6(11), 2752-2763. DOI: 10.3390/polym6112752
Caykara, T., and Güven, O. (1999). “UV degradation of poly (methyl methacrylate) and its vinyltriethoxysilane containing copolymers,” Polymer Degradation and Stability 65(2), 225-229. DOI: 10.1016/S0141-3910(99)00008-7
Charlesby, A., and Thomas, D. (1962). “A comparison of the effects of ultra-violet and gamma radiation in polymethylmethacrylate,” Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 269(1336), 104-124. DOI: 10.1098/rspa.1962.0165
Choi, H., Woo, H. J., Hong, W., Kim, J. K., Lee, S. K., and Eum, C. H. (2001). “Structural modification of poly (methyl methacrylate) by proton irradiation,” Applied Surface Science 169, 433-437. DOI: 10.1016/S0169-4332(00)00699-1
Choi, J., Moore, J. A., Corelli, J. C., Silverman, J. P., and Bakhru, H. (1988). “Degradation of poly (methylmethacrylate) by deep ultraviolet, x‐ray, electron beam, and proton beam irradiations,” Journal of Vacuum Science and Technology B 6(6), 2286-2289. DOI: 10.1116/1.584071
Clough, R. L., and Shalaby, S. W. (1991). Radiation Effects on Polymers, American Chemical Society, Washington, DC.
Davis, A., and Sims, D. (1983). Weathering of Polymers, Elsevier Applied Science Publisher, UK.
Dixit, M., Mathur, V., Gupta, S., Baboo, M., Sharma, K., and Saxena, N. S. (2009). “Morphology, miscibility and mechanical properties of PMMA/PC blends,” Phase Transitions 82(12), 866-878. DOI: 10.1080/01411590903478304
Dole, M. (2013). The Radiation Chemistry of Macromolecules, Vol. 2, Academic Press, New York, NY.
Edgar, K. J., Buchanan, C. M., Debenham, J. S., Rundquist, P. A., Seiler, B. D., Shelton, M. C., and Tindall, D. (2001). “Advances in cellulose ester performance and application,” Progress in Polymer Science 26(9), 1605-1688. DOI: 10.1016/S0079-6700(01)00027-2
Fekete, E., and Pukánszky, B. (2005). “Effect of molecular interactions on the miscibility and structure of polymer blends,” European Polymer Journal 41(4), 727-736. DOI: 10.1016/j.eurpolymj.2004.10.038
Fox, R. B., Isaacs, L. G., and Stokes, S. (1963). “Photolytic degradation of poly (methyl methacrylate),” Journal of Polymer Science Part A: General Papers 1(3), 1079-1086. DOI: 10.1002/pol.1963.100010321
Gajria, A. M., Davé, V., Gross, R. A., and McCarthy, S. P. (1996). “Miscibility and biodegradability of blends of poly (lactic acid) and poly (vinyl acetate),” Polymer 37(3), 437-444. DOI: 10.1016/0032-3861(96)82913-2
Guinier, A. (1994). X-Ray Diffraction in Crystals, Imperfect Crystals, and Amorphous Bodies, Courier Corporation, Chicago, IL. DOI: 10.1016/0032-3861(87)90207-2
Gupta, P., and Singh, K. (1996). “Characterization of H3PO4 based PVA complex system,” Solid State Ionics 86-88, 319-323. DOI: 10.1016/0167-2738(96)00139-7
He, Y., Zhu, B., and Inoue, Y. (2004). “Hydrogen bonds in polymer blends,” Progress in Polymer Science 29(10), 1021-1051. DOI: 10.1016/j.progpolymsci.2004.07.002
Heijboer, J., Baas, J. M. A., van de Graaf, B., and Hoefnagel, M. A. (1987). “A molecular mechanics study on rotational motions of side groups in poly (methyl methacrylate),” Polymer 28(3), 509-513. DOI: 10.1016/0032-3861(87)90207-2
Holland, B., and Hay, J. (2001). “The kinetics and mechanisms of the thermal degradation of poly (methyl methacrylate) studied by thermal analysis-Fourier transform infrared spectroscopy,” Polymer42(11), 4825-4835. DOI: 10.1016/S0032-3861(00)00923-X
Hu, Y.-H., and Chen, C.-Y. (2003). “The effect of end groups on the thermal degradation of poly (methyl methacrylate),” Polymer Degradation and Stability 82(1), 81-88. DOI: 10.1016/S0141-3910(03)00165-4
Huang, S.-H., Chiang, Y.-W., and Hong, J.-L. (2015). “Luminescent polymers and blends with hydrogen bond interactions,” Polymer Chemistry 6(4), 497-508. DOI: 10.1039/C4PY01146E
Jeon, G. W., An, J.-E., and Jeong, Y. G. (2012). “High performance cellulose acetate propionate composites reinforced with exfoliated graphene,” Composites Part B: Engineering 43(8), 3412-3418. DOI: 10.1016/j.compositesb.2012.01.023
Jeong, H., Rooney, M., David, D. J., MacKnight, W. J., Karasz, F. E., and Kajiyama, T. (2000). “Miscibility and characterization of the ternary crystalline system: Poly (vinyl butyral)/poly (vinyl alcohol)/nylon6,” Polymer 41(17), 6671-6678. DOI: 10.1016/S0032-3861(99)00872-1
Kashiwagi, T., Inaba, A., Brown, J. E., Hatada, K., Kitayama, T., and Masuda, E. (1986). “Effects of weak linkages on the thermal and oxidative degradation of poly (methyl methacrylates),” Macromolecules 19(8), 2160-2168. DOI: 10.1021/ma00162a010
Kunthadong, P., Molloy, R., Worajittiphon, P., Leejarkpai, T., Kaabbuathong, N., and Punyodom, W. (2015). “Biodegradable plasticized blends of poly (L-lactide) and cellulose acetate butyrate: From blend preparation to biodegradability in real composting conditions,” Journal of Polymers and the Environment 23(1), 107-113. DOI: 10.1007/s10924-014-0671-x
Lehrle, R., and Place, E. (1997). “Degradation mechanisms of poly (methyl acrylate)—II. The contribution of depropagation with intramolecular transfer,” Polymer Degradation and Stability 56(2), 221-226. DOI: 10.1016/S0141-3910(96)00204-2
Manaf, M. E. A., Tsuji, M., Nobukawa, S., and Yamaguchi, M. (2011). “Effect of moisture on the orientation birefringence of cellulose esters,” Polymers 3(2), 955-966. DOI: 10.3390/polym3020955
Manring, L. E., Sogah, D. Y., and Cohen, G. M. (1989). “Thermal degradation of poly (methyl methacrylate). 3. Polymer with head-to-head linkages,” Macromolecules 22(12), 4652-4654. DOI: 10.1021/ma00202a048
Manson, J. A. (2012). Polymer Blends and Composites, Springer Science & Business Media, New York, NY. DOI: 10.1007/978-1-4615-1761-0
Mathur, A., Kavthia, S. H., Mehta, N. M., and Parsania, P. H. (2003). Testing and Evaluation of Plastics, Allied Publishers, New Delhi, India.
Menard, K. P. (2008). Dynamic Mechanical Analysis: A Practical Introduction, CRC Press, Boca Raton, FL. DOI: 10.1201/9781420053135
Merenga, A. S., and Katana, G. (2010). “Dynamic mechanical analysis of PMMA-cellulose blends,” International Journal of Polymeric Materials 60(2), 115-123. DOI: 10.1080/00914030903538553
Michelson, J., Werner, L., Ollerton, A., Leishman, L., and Bodnar, Z. (2012). “Light scattering and light transmittance in intraocular lenses explanted because of optic opacification,” Journal of Cataract & Refractive Surgery 38(8), 1476-1485. DOI: 10.1016/j.jcrs.2012.03.038
Moore, L., and Ferreira, J. T. (2006). “Ultraviolet (UV) transmittance characteristics of daily disposable and silicone hydrogel contact lenses,” Contact Lens and Anterior Eye 29(3), 115-122. DOI: 10.1016/j.clae.2006.03.002
Nesterov, A. E., and Lipatov, Y. S. (1998). Thermodynamics of Polymer Blends, Technomic Publishing Company, Lancaster, PA.
Nobukawa, S., Aoki, Y., Yoshimura, H., Tachikawa, Y., and Yamaguchi, M. (2013). “Effect of aromatic additives with various alkyl groups on orientation birefringence of cellulose acetate propionate,” Journal of Applied Polymer Science 130(5), 3465-3472.
Nobukawa, S., Enomoto-Rogers, Y., Shimada, H., Iwata, T., and Yamaguchi, M. (2015). “Effect of acetylation site on orientation birefringence of cellulose triacetate,” Cellulose 22(5), 3003-3012. DOI: 10.1007/s10570-015-0730-z
Nobukawa, S., Hayashi, H., Shimada, H., Kiyama, A., Yoshimura, H., Tachikawa, Y., and Yamaguchi, M. (2014). “Strong orientation correlation and optical anisotropy in blend of cellulose ester and poly (ethylene 2, 6‐naphthalate) oligomer,” Journal of Applied Polymer Science 131(15). DOI: 10.1002/app.40570
Olabis, O. (2012). Polymer-Polymer Miscibility, Academic Press, New York, NY.
Osuagwu, U. L., and Ogbuehi, K. C. (2014). “UV–vis light transmittance through tinted contact lenses and the effect of color on values,” Contact Lens and Anterior Eye 37(3), 136-143. DOI: 10.1016/j.clae.2013.09.004
Park, D., Stewart, K. J., and Kumar, A. (2014). “Experiential optical device,” Appl. No.: 14/184,15, Google Patents US Patent 20140232978 A1.
Park, J. W., Doi, Y., and Iwata, T. (2005). “Unique crystalline orientation of poly [(R)-3-hydroxybutyrate]/cellulose propionate blends under uniaxial drawing,” Macromolecules 38(6), 2345-2354. DOI: 10.1021/ma0481611
Paul, D. R. (2012). Polymer Blends, Academic Press, New York, NY.
Ramesh, S., and Arof, A. (2001). “Structural, thermal and electrochemical cell characteristics of poly (vinyl chloride)-based polymer electrolytes,” Journal of Power Sources 99(1), 41-47.
Ramesh, S., Liew, C.-W., Morris, E., and Durairaj, R. (2010). “Effect of PVC on ionic conductivity, crystallographic structural, morphological and thermal characterizations in PMMA–PVC blend-based polymer electrolytes,” Thermochimica Acta 511(1), 140-146. DOI: 10.1016/j.tca.2010.08.005
Rinderknecht, S., and Brisson, J. (1999). “Orientation of a miscible polymer blend with strong interchain hydrogen bonds: Poly (vinylphenol)-poly (ethylene oxide),” Macromolecules 32(25), 8509-8516. DOI: 10.1021/ma9808575
Salamone, J. C. (1998). Concise Polymeric Materials Encyclopedia, Vol. 1, CRC Press, Boca Raton, FL.
Silverstein, R. M., Webster, F. X., and Kiemle, D. J. (2014). Spectrometric Identification of Organic Compounds, John Wiley and Sons, New York, NY.
Souza, D., Castillo, T. E., and Rodríguez, R. J. S. (2012). “Effects of hydroxyvalerate contents in thermal degradation kinetic of cellulose acetate propionate/poly (3-hydroxyalkanoates) blends,” Journal of Thermal Analysis and Calorimetry 109(3), 1353-1364. DOI: 10.1007/s10973-011-2152-y
Teng, H., Koike, K., Zhou, D., Satoh, Z., Koike, Y., and Okamoto, Y. (2009). “High glass transition temperatures of poly (methyl methacrylate) prepared by free radical initiators,” Journal of Polymer Science Part A: Polymer Chemistry 47(1), 315-317. DOI: 10.1002/pola.23154
Torikai, A., Ohno, M., and Fueki, K. (1990). “Photodegradation of poly (methyl methacrylate) by monochromatic light: Quantum yield, effect of wavelengths, and light intensity,” Journal of Applied Polymer Science 41(5–6), 1023-1032. DOI: 10.1002/app.1990.070410513
Wang, H., Xu, P., Zhong, W., Shen, L., and Du, Q. (2005). “Transparent poly (methyl methacrylate)/silica/zirconia nanocomposites with excellent thermal stabilities,” Polymer Degradation and Stability 87(2), 319-327. DOI: 10.1016/j.polymdegradstab.2004.08.015
Yamaguchi, M., and Arakawa, K. (2007a). “Control of structure and mechanical properties for binary blends of poly (3‐hydroxybutyrate) and cellulose derivative,” Journal of Applied Polymer Science103, 3447-3452.
Yamaguchi, M., and Masuzawa, K. (2007b). “Birefringence control for binary blends of cellulose acetate propionate and poly (vinyl acetate),” European Polymer Journal 43(8), 3277-3282. DOI: 10.1016/j.eurpolymj.2007.06.007
Yamaguchi, M., Okada, K., Manaf, M. E. A., Shiroyama, Y., Iwasaki, T., and Okamoto, K. (2009). “Extraordinary wavelength dispersion of orientation birefringence for cellulose esters,” Macromolecules 42(22), 9034-9040. DOI: 10.1021/ma901676j
Article submitted: October 26, 2015; Peer review completed: February 7, 2016; Revised version received and accepted: February 18, 2016; Published: February 22, 2016.
DOI: 10.15376/biores.11.2.3466-3480