Selected  Molding  Conditions.Prior  to  studying  the  effects
of  the VAIM  process,  a  large  number  of  specimens  were  molded
and  mechanically  tested.  Through  an  optimization  process  a  full
set  of  conventional  molding  conditions  that  yielded  the  strongest
products  was  determined.  As  it  turned  out,  the  optimal  molding
conditions  for  the  virgin  material  exactly  matched  those  for  the
recycled  material.  These  conditions  are  presented  in  Table  1.
Since  the  optimal  molding  conditions  for  100%  virgin  and  100%
recycled  PS  were  found  to  be  identical,  it  was  concluded  that these  conditions  would  also  be  best  for  the  blended  mixtures.Thus,  throughout  the  remainder  of  the  investigation,  the  processing  conditions  shown  in  Table  1  were  applied  regardless  of whether  or  not  vibration  assistance  was  utilized.
Table 1 Optimized molding conditions utilized throughout the
investigation
Injection  time 0.5  s
Holding  time 19.5  s
Cooling  time 15  s
Injection  pressure 45  Mpa
Holding  pressure 45  Mpa
Mold  temperature 70°C
Nozzle  temperature 210°C
Barrel  temperature ( front) 205°C
Barrel  temperature (rear )200°C
Range of Vibration Parameters Studied. The hydraulic system  of  the  BOY  15S  molding  machine  is  capable  of  producing suitable  injection  screw  oscillations  at  frequencies  up  to  9  Hz.Therefore,  the  frequency  range  studied  during  the  present  effort was  from  1  to  8  Hz.  The  delay  times  to  begin  vibration  ranged from 0.0 to 1.0 s, and vibration duration levels ranged from 4.0 to 12.0 s. Lastly, duty cycles between 1.0 and 3.0 were investigated.
Within  the  window  of  the  parameter  levels  specified   above,  an experimental optimization process was carried out that focused on arriving  at  sets  of  VAIM  processing  conditions  that  would  yield the  strongest  products  for  each  of  the  material  blends  studied.During  this  process,  approximately  900  sample  specimens  were manufactured  and  tested  for  each  material  combination.  The  results  that  were  generated  are  presented  throughout  the  remainder of  this  paper.
Results  and  Discussion
Baseline  Results. To  study  the  effects  of  VAIM  processing,results  with  conventionally  molded  products  needed  to  be  obtained first  for comparison purposes. Along this line, 30 test specimens were produced from both the 100% virgin (100/0 hereafter),100% recycled (0/100 hereafter), 75%/25% virgin/recycled (75/25Hereafter),  and  50%/50%  virgin/recycled (50/50  hereafter) PS blends  using  the  optimized  conventional  molding  conditions  discussed  earlier. These  samples  were  then  mechanically  tested,  and the  ultimate  tensile  strength (UTS) distributions  that  resulted  are shown  in  Fig.  1. 回收塑料材料注射成型英文文献和中文翻译(5):http://www.751com.cn/fanyi/lunwen_17270.html