param(
    [Parameter(Mandatory=$true)][string]$InputDirectory,
    [Parameter(Mandatory=$true)][string]$PdfDirectory
)
$ErrorActionPreference = 'Stop'
New-Item -ItemType Directory -Force -Path $PdfDirectory | Out-Null
$word = New-Object -ComObject Word.Application
$word.Visible = $false
$word.DisplayAlerts = 0
try {
    foreach ($file in Get-ChildItem -LiteralPath $InputDirectory -Filter '*.docx') {
        $doc = $word.Documents.Open($file.FullName, $false, $true)
        try {
            $doc.Repaginate()
            $pdf = Join-Path $PdfDirectory ($file.BaseName + '.pdf')
            $doc.ExportAsFixedFormat($pdf, 17)
        } finally {
            $doc.Close($false)
            [System.Runtime.InteropServices.Marshal]::ReleaseComObject($doc) | Out-Null
        }
    }
} finally {
    $word.Quit()
    [System.Runtime.InteropServices.Marshal]::ReleaseComObject($word) | Out-Null
    [GC]::Collect()
    [GC]::WaitForPendingFinalizers()
}