How to make the light diffusion masterbatch and its effect on the Properties of Polycarbonate Composites

The unique structure of light diffusion agent makes it show special optical properties, and the polymer modified by it can meet the requirements of some special optical materials. To achieve good optical properties, the effects of optical diffuser on the optical properties, low-light morphology, mechanical properties and thermal stability of PC were studied by changing the filling amount of light diffusion agent.

The traditional preparation method of light diffusion is to add auroral diffuser to PC, and the light will refract through the surface of tiny particles for many times to achieve the effect of leveling light. However, light can not pass through these inorganic particles, resulting in a large loss of light energy, which is difficult to achieve the incremental effect. The present organic light diffuser itself can penetrate light, and the loss of light energy is small, which can effectively achieve the effect of uniform light and light transmission. The main technical parameters for characterizing light diffusion composites include light transmittance and haze. In general, the increase of haze will lead to the decrease of light transmittance, and the transmission management of the lampshade used in daily life is not high, in other words, part of the light energy has been lost, so the development of optical diffusion composites with excellent optical properties can effectively save electric energy.

2.1 Experimental materials
The chemical reagents used in the experiment are shown in Table 2-1.

Tabel 2.1 Materials and reagents

Material	Specification
PC	／
KMP590	um
PMMA	um
TiO2	um

2.2 main instruments and equipment used in the experiment

a. Electric constant temperature blast drying oven

b. Twin screw co-directional extruder

c. Plastic injection molding machine

d. Light transmittance/haze tester

e. Notched prototype

f. Electro-optic analytical balance

2.3 Experimental formulation of PC/KMP590 composites

2.4Experimental formulation of PC/PMMA composite materials

2.5Experimental Formula of PC/KMP590-Ti Composites

2.6 Experimental formulation of PC/PMMA-Ti composite materials

(1) Particle size and particle size distribution.
According to the data of particle size and particle size distribution, the average particle size and particle size distribution are obtained.
The light diffusion was dispersed in ethanol and diluted to a certain concentration, and the 5min was dispersed by ultrasound. The particle size was analyzed by Zetasize 3000HSA nano-particle size and potential analyzer (particle size analysis range is 2-3000nm) made by Malvern company in England.

(2) Transmission electron microscope (TEM).
Transmission electron microscope (TME) transmits the accelerated and concentrated electron beam to a very thin sample, and the electrons collide with the atoms in the sample to change the direction, resulting in three-dimensional angular scattering. The scattering angle is related to the density and thickness of the sample, so it can form different light and dark images, which are mainly used to observe the micro-morphology and real particle size of granular materials.
A proper amount of light diffuser was dispersed in ethanol solution and 20min was super-dispersed. The samples were dried on the film-loaded copper net by suspension method, and the talc powder was analyzed by TEM with JEOL 200CX transmission electron microscope.

(3) scanning electron microscope (SEM).
Scanning electron microscope (SEM) is an analytical method to observe the distribution and dispersion of granular materials by using electrion beam to form a variety of signals after many elastic and inelastic scattering on the sample surface and to receive and process these signals. Finally, it shows the surface morphology of the sample on the picture tube.

The SEM analysis of the light diffusion agent was carried out by JSM-6700F high-resolution scanning electron microscope. Because the light diffusion agent does not conduct electricity, gold was sprayed on the sample surface by LDM150D sputtering instrument before SEM analysis to reduce the charge accumulation.

(4) Haze test of light transmittance.
Because the light diffuser is a powder, the light diffuser is surprised and pressed before the test, and then the fog transmittance is tested by the light transmittance/haze tester. The formula is:
Light transmittance% = total light transmission through the sample / incident light flux * 100%.
haze% = (scattered luminous flux of the instrument and test/total transmitted luminous flux passing through the sample-scattered luminous flux of the instrument/incident luminous flux)

(5) Burning residue test.
Accurately weigh a certain amount of light diffusion masterbatch, then put it into a box-type resistance furnace, burn it at 600 degrees Celsius for 4 hours, and then weigh it out, so as to determine the burning residue. The formula is:
Actual content% = post-burning g / pre-burning g * 100%

(6) whiteness test.
The whiteness of light diffusion is tested by using a whiteness tester.

2.5 results and discussion.

2.5.1 performance Analysis of Optical Diffusion Agent and Experimental Analysis of Burning residue of Optical Diffusion Masterbatch.
(1) Particle size and particle size distribution.
The particle size distribution of the three light diffusion agent is shown in figure 2.1. The average particle size of KMP590 is 2.2um, the average particle size of Tio is 3.0um, and the average particle size of Tio is 190nm. The particle size distribution range of KMP590 and PMMA is small, and Tio has multiple particle size distribution ranges.

(2) microscopic morphology.
The TEM analysis of the light diffusion agent is shown in figure 2.2. As can be seen from the figure, the structure of KMP590 is regular and spherical, the structure of PMMA is regular and spherical, and the structure of TiO2 is irregular and particle type.

(2) microscopic morphology.
The TEM analysis of the light diffusion agent is shown in figure 2.2. As can be seen from the figure, the structure of KMP590 is regular and spherical, the structure of PMMA is regular and spherical, and the structure of Tio is irregular and particle type.

The SEM image analysis of the light diffusion agent is shown in figure 2.3. As can be seen from the figure, from figure a, the shape of Tio2 is irregular, it is a particle type, and the particle size is about 190nm. Figure b shows that the shape of KMP590 is regular, the particle size distribution is more uniform, the particle size is about 2.2um, and figure C shows that the shape of PMMA is more regular, the particle size distribution is uniform, and the size of Lingjing is about 3um.

(3) transmittance/haze analysis.
The light diffuser was pressed into the tablet, and the light transmittance of the fog was tested by the light transmittance/fog tester. This paper gives a better explanation for the change of optical properties of light diffusion. Table 2.7shows the data of fog and light transmittance of light diffuser, it can be seen that the light transmittance of Tio2 is relatively low, and the fog is relatively high, which has a great influence on the optical properties of the material.

The whiteness test data of the light diffuser are shown in figure 2.8. the whiteness of Tio2 is low, and the addition of too much Tio2 will make the composite yellowing, so we add a very small amount of Tio2 in the preparation process.

(4) Masterbatch burning residue test.
Table 2.9 shows the experimental data of masterbatch burning residue, and the actual proportion of the prepared masterbatch is close to the theoretical proportion (the error range is “0.6%). It is determined that the content of light diffuser in three kinds of masterbatch MKMP590 and MPMMA, MTio2 is 9.74wt%, 9.56wt%, 9.46wt% respectively. The content of light diffuser in PC light diffusion material is more accurate.

2.5.2 property Analysis of Optical Diffusion Composites.

(1) Optical performance analysis.
The light transmittance of pure PC is 89%-92%, and the fog is 14%-16%. The change of the optical properties of the light diffusion material is mainly due to the light diffusion phenomenon of the material, and the change of the optical property of the light diffusion material is mainly due to the light diffusion phenomenon of the material, and the root cause of the light diffusion phenomenon is the destruction of the uniformity of the medium. When the particle size in the medium reaches the order of magnitude of the wavelength of visible light, if there is a certain difference in the refractive index between the dispersed phase and the continuous phase, the dispersed phase particles can be used as the source of stimulating wavelets under the action of social light. The data deviation of optical properties of composites was studied by repetitive experiments.

It can be seen from figure 2.4 that the light transmittance of the composite decreases with the increase of the KMP590 content of the light diffuser. When the KMP590 content reaches 2.0%, the light transmittance is 54.5%. The average deviation of the repeated experiment is 0.222-0.376%, and the standard deviation is 0.304-0.75%. As can be seen from figure 2.5, with the increase of the KMP590 content of the light diffuser, the haze of the composite increases, and when the KMP590 content reaches 2.0%, the haze of the composite increases. The haze is 92.8%, the average deviation of repeated experiments is 0.216-0.4%, and the standard deviation is 0.305-0.519%. This is due to the scattering phenomenon of light production rate caused by light diffuser in PC matrix in China. The repeated experimental data show that the masterbatch process is stable, and the average deviation and standard deviation are small.

As can be seen from figure 2.6, with the increase of the KMP590 content of the light diffuser (the Tio2 content is constant), the light transmittance of the composite decreases. When the KMP590 content reaches 2.0%, the light transmittance is 54.2%. The average deviation of the repeated experiment is 0.353-1.860%, and the standard deviation is 0.452-2.490%. As can be seen from figure 2.7, with the increase of the KMP590 content of the light diffusion agent (the Tio2 content remains the same), the fog of the composite increases. When the KMP590 content reaches 2.0%, the fog is 94.8%. The repeated experimental data show that the masterbatch process is stable, and the average deviation and standard deviation are small.

It can be seen from figure 2.8 that the light transmittance of the composite decreases with the increase of the PMMA content of the light diffuser, and when the PMMA content reaches 2.0%, the light transmittance of the composite is 59.5%. As can be seen from figure 2.9, with the increase of the PMMA content of the light diffuser, the fog of the composite increases, and when the PMMA content reaches 2.0%, the haze is 92.5%. Repeated experiments show that the masterbatch process is stable.

As can be seen from figure 2.10, with the increase of the PMMA content of the light diffusion agent (the Tio2 content is constant), the fog of the composite increases, and when the PMMA content reaches 2.0%, the haze is 94.2%. Repeated experiments show that the masterbatch process is stable.
According to the optical test data, the optical properties of the prepared optical diffusion composites can be compounded. Light transmittance > 50%, fog > 90%. The scattering effect of PMMA is better than that of KMP590. The repeated experimental data show that the masterbatch process is stable and the standard deviation is small.

Figure 2.12 and figure 2.13 show that the light transmittance of the light diffusion composite with inorganic nano-masterbatch Tio2 is similar to that without addition. From figure 2.14 and figure 2.15, it can be seen that the addition of inorganic light diffuser nano-masterbatch Tio2 has an obvious effect on the haze of the material.

(2) Analysis of pull performance.
Figure 2.16 shows the tensile strength curve of the light diffusion agent composites filled with PC with 0: 2.0% (wt) light diffuser.
As can be seen from the figure, with the increase of the content of light diffusion particles, it has little effect on the tensile strength of light diffusion composites, which is about 60MPa, this is because the light diffuser particles are not easy to produce stress concentration effect.

(3) impact performance analysis.

Figure 2.17 shows the impact strength curve of the light diffusion composite after filling PC with 0: 2.0% (wt) optical diffuser. The addition of light diffusion KMP590 has little effect on the impact of light diffusion composites. After the addition of light diffusion agent PMMA, the impact property decreases, from about 70kJ/m2 of pure PC to about 18kJ/m2. This is because the particle size of PMMA is about 3um, which is easy to cause defects, resulting in a significant decrease in impact strength.

(4) Thermal performance analysis.
The sample was studied by TA DSC 822 differential scanning calorimeter. The sample quantity 8~10mg was heated to 600K at the heating rate of 10K/min, and the constant temperature 5min was reduced to room temperature at the rate of eliminating thermal history 10K/min, and the change of heat content in the cooling process was recorded.

Figure 2.18 shows the non-isothermal crystallization curve of light diffusion composites, from which it can be seen that the Tg (glass conversion temperature) of plastics decreases with the addition of light diffuser. Because the light diffusion agent particles contribute to the short movement of the molecular chain of PC particles, the Tg decreases.

(5) SEM image analysis.
Whether the optical diffuser is uniformly dispersed in the PC matrix is one of the important factors affecting the optical properties of PC composites. The SEM images of the photodiffusion composites were analyzed. Figure 2.19 is the SEM picture of the liquid nitrogen quenching fracture section of the photodiffusion composites.

It can be seen from the figure that the optical diffuser with an average particle size of 2.2um is uniformly dispersed in PC, and the light diffusion agent still shows a spherical structure, and the composite prepared by masterbatch method makes the light diffusion agent well dispersed in the composite, which is beneficial to the improvement of optical properties.

2.6 Summary of this chapter.
This chapter discusses the preparation of LDA masterbatch by using light diffusion agent and polycarbonate as raw materials, and the preparation and properties of light diffusion agent composite. Through the type of light diffusion agent and the filling amount of light diffusion agent, the effect of light diffusion agent on the composites was studied.

• 1). The optical properties of the optical diffuser were studied by testing the haze, transmittance and whiteness of the light diffusion agent. The microstructure analysis and particle size test of light diffusion observed by SEM,TEM show that the structure of light diffusion agent KMP590 is spherical and the particle size is about 2.2um, the structure of light diffusion agent PMMA is spherical and the particle size is about 3.0um, and the structure of light diffusion agent Tio2 is irregular and the particle size is about 190nm. Through the burning residue experiment of the masterbatch, it is determined that the content of light diffuser in three kinds of masterbatch MK590, PMMA and MTio2 is 9.74wt%, 9.56wt% and 9.46%, so that the content of light diffuser in PC light diffusion material has more accurate content.

• 2). With the increase of KMP590 content of light diffuser, the light transmittance of light diffusion composites decreases and the fog increases. The process of the composites prepared by twin screw masterbatch method is stable, the repeated experiments are small, and the standard deviation is between 0.265% and 2.490%. The scattering effect of light diffuser PMMA is slightly better than that of the composites with KMP590; and Tio2. Compared with the composites without Tio2, the light transmittance of the composites has little difference, but the fog increases obviously.

• 3). Through the SEM image analysis of the prepared light diffusion composites, it is concluded that the light diffusion composites prepared by the twin-screw masterbatch method are uniformly dispersed and the shape is intact.

• 4). With the addition of light diffuser, the pull-up properties of light diffusion composites change little, which is about 60MPa. With the addition of light diffusion KMP590, it has little effect on the impact properties of light diffusion composites, but after the addition of light diffuser PMMA, the impact property decreases, from about 70kJ/m2 of pure PC to about 18kJ/m2.

• 5). With the addition of light diffuser, the Tg (glass conversion temperature) of plastics decreased, and the thermal properties decreased slightly.